Academic Appointments

Honors & Awards

  • Norman E. Shumway Award Research Award, The Western Thoracic Surgical Association (2013)
  • Chief Resident Teaching Award, Massachusetts General Hospital (2009)
  • Awarded Excellence in Teaching Citation, Tufts University School of Medicine (2008)
  • New Era Cardiac Care Scholar, - (2006)
  • Alpha Omega Alpha, President, UCSF Chapter (2000-2001)
  • UC Regents Scholar, University of California at San Francisco (1996-2001)
  • Phi Beta Kappa, - (1995)
  • Graduated with Highest Distinction in General Scholarship, University of California at Berkeley (1995)
  • Departmental Honors Thesis in Molecular and Cellular Biology, University of California at Berkeley (1995)
  • Dean's List, University of California at Berkeley (1992-1995)
  • Edward Frank Kraft Scholarship, University of California at Berkeley (1993)

Professional Education

  • Board Certification, American Board of Thoracic Surgery, Thoracic Surgery (2013)
  • Transplant Fellowship, Stanford University, Cardiothoracic Transplantation and Mechanical Circulatory Support (2013)
  • Post-doctoral Fellowship, Stanford University, Cardiac stem cell therapy (2007)
  • AB, summa cum laude, University of California at Berkeley, Molecular and Cellular Biology (1995)

Research & Scholarship

Current Research and Scholarly Interests

Surgical simulation and education
Molecular imaging of cardiac stem cell therapy
Heart failure
Cardiothoracic transplantation


Journal Articles

  • Individual differences in field independence influence the ability to determine accurate needle angles JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Sheikh, A. Y., Keehner, M., Walker, A., Chang, P. A., Burdon, T. A., Fann, J. I. 2014; 148 (5): 1804-1810
  • In Vivo Functional and Transcriptional Profiling of Bone Marrow Stem Cells After Transplantation Into Ischemic Myocardium ARTERIOSCLEROSIS THROMBOSIS AND VASCULAR BIOLOGY Sheikh, A. Y., Huber, B. C., Narsinh, K. H., Spin, J. M., van der Bogt, K., de Almeida, P. E., Ransohoff, K. J., Kraft, D. L., Fajardo, G., Ardigo, D., Ransohoff, J., Bernstein, D., Fischbein, M. P., Robbins, R. C., Wu, J. C. 2012; 32 (1): 92-102


    Clinical trials of bone marrow-derived stem cell therapy for the heart have yielded variable results. The basic mechanism(s) that underlies their potential efficacy remains unknown. In the present study, we evaluated the survival kinetics, transcriptional response, and functional outcome of intramyocardial bone marrow mononuclear cell (BMMC) transplantation for cardiac repair in a murine myocardial infarction model.We used bioluminescence imaging and high-throughput transcriptional profiling to evaluate the in vivo survival kinetics and gene expression changes of transplanted BMMCs after their engraftment into ischemic myocardium. Our results demonstrate short-lived survival of cells following transplant, with less than 1% of cells surviving by 6 weeks posttransplantation. Moreover, transcriptomic analysis of BMMCs revealed nonspecific upregulation of various cell regulatory genes, with a marked downregulation of cell differentiation and maturation pathways. BMMC therapy caused limited improvement of heart function as assessed by echocardiography, invasive hemodynamics, and positron emission tomography. Histological evaluation of cell fate further confirmed findings of the in vivo cell tracking and transcriptomic analysis.Collectively, these data suggest that BMMC therapy, in its present iteration, may be less efficacious than once thought. Additional refinement of existing cell delivery protocols should be considered to induce better therapeutic efficacy.

    View details for DOI 10.1161/ATVBAHA.111.238618

    View details for Web of Science ID 000298288700014

    View details for PubMedID 22034515

  • Immediate Postoperative Percutaneous Stenting of Superior Vena Cava Obstruction Following Heart Transplantation in Adult Patients with Pacemaker Leads JOURNAL OF CARDIAC SURGERY Asseff, D., Sheikh, A. Y., Sze, D., Ha, R., Hofmann, L., van der Starre, P. J. 2014; 29 (5): 733-736

    View details for DOI 10.1111/jocs.12387

    View details for Web of Science ID 000342851100031

  • A novel, catheter-based approach to left ventricular assist device deactivation after myocardial recovery. Annals of thoracic surgery Zeigler, S. M., Sheikh, A. Y., Lee, P. H., Desai, J., Banerjee, D., Oyer, P., Dake, M. D., Ha, R. V. 2014; 98 (2): 710-713


    We describe a case of catheter-based embolization and deactivation of a left ventricular assist device using an Amplatzer plug for a patient demonstrating myocardial recovery after diagnosis of nonischemic cardiomyopathy. This procedure can provide a minimally invasive, low morbidity solution for patients wishing to be separated from left ventricular assist device support who want to avoid invasive surgery for device removal.

    View details for DOI 10.1016/j.athoracsur.2013.09.073

    View details for PubMedID 25087798

  • Resource use trends in extracorporeal membrane oxygenation in adults: An analysis of the Nationwide Inpatient Sample 1998-2009. journal of thoracic and cardiovascular surgery Maxwell, B. G., Powers, A. J., Sheikh, A. Y., Lee, P. H., Lobato, R. L., Wong, J. K. 2014; 148 (2): 416-421 e1


    The study objective was to determine whether significant trends over time have occurred in resource use associated with the use of extracorporeal membrane oxygenation in critically ill adults.All adult admissions involving extracorporeal membrane oxygenation were examined by using the Nationwide Inpatient Sample database (years 1998-2009). Trends in volume, outcome, and resource use (including hospital charges, length of stay, and charges per day) were analyzed.An estimated total of 8753 admissions involved extracorporeal membrane oxygenation over the study period. Overall length of stay was 18.3 ± 1.3 days. Total hospital charges averaged $344,009 ± $30,707 per admission, with average charges per day of $40,588 ± $3099. Cumulative national charges for extracorporeal membrane oxygenation admissions increased significantly from $109.0 million in 1998 to $764.7 million in 2009 (P = .0016). Charges per patient and length of stay also increased significantly (P = .0032 and .0321, respectively). The increasing trend in the number of extracorporeal membrane oxygenation admissions during the study period was not statistically significant (P = .19). The post-cardiotomy group had more favorable outcomes and lower resource use. A shift was observed in the relative case-mix of extracorporeal membrane oxygenation admissions over the study period, with a relative decrease in the post-cardiotomy group and increases in the cardiogenic shock, respiratory failure, and lung transplant groups.These results suggest that dramatic increases in resource use associated with extracorporeal membrane oxygenation are not solely the result of increased volume, but in part are due to a shift toward extracorporeal membrane oxygenation use in patient groups (other than in the post-cardiotomy setting) with greater resource use and worse outcomes.

    View details for DOI 10.1016/j.jtcvs.2013.09.033

    View details for PubMedID 24183903

  • Heart transplantation with or without prior mechanical circulatory support in adults with congenital heart disease EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY Maxwell, B. G., Wong, J. K., Sheikh, A. Y., Lee, P. H., Lobato, R. L. 2014; 45 (5): 842-846


    Recent analyses establish that heart transplantation is increasing among adults with congenital heart disease (ACHD), but the effects of pretransplant mechanical circulatory support (MCS) on perioperative and post-transplant outcomes have not been examined in the ACHD population.Scientific Registry of Transplant Recipients data on all adult heart transplants from September 1987 to September 2012 (n = 47 160) were classified based on primary diagnosis codes as CHD or non-CHD and MCS or non-MCS. Demographic, procedural, outcome and survival variables were compared between MCS and non-MCS ACHD patient groups.MCS was used in 83 (6.8%) ACHD patients compared with 8625 (18.8%) patients without CHD (P < 0.001). MCS as a fraction of ACHD transplants increased over time (P = 0.002). MCS patients spent more time on the wait list, had a higher baseline serum creatinine and were more likely to be male, status 1A, hospitalized, in the ICU and/or on a ventilator prior to transplant. However, MCS patients experienced equivalent short-term survival (30-day mortality = 10.8% in MCS vs 13.5% in non-MCS, P = 0.62) and overall survival by Kaplan-Meier analysis (P = 0.57). MCS patients had a longer post-transplant length of stay and were more likely to be transfused, but otherwise had no significant differences in adverse outcomes.MCS is less commonly used in adult CHD patients compared with all patients undergoing heart transplant, but has been increasing over time. Within the ACHD population, patients with MCS have a higher risk profile, but except for increased transfusion rate and longer length of stay, do not experience less favourable post-transplant outcomes.

    View details for DOI 10.1093/ejcts/ezt498

    View details for Web of Science ID 000334791700022

    View details for PubMedID 24135956

  • Open aortic valve replacement in a patient with Glanzmann's thrombasthenia: a multidisciplinary strategy to minimize perioperative bleeding TRANSFUSION Sheikh, A. Y., Hill, C. C., Goodnough, L. T., Leung, L. L., Fischbein, M. P. 2014; 54 (2): 300-305


    BACKGROUND: Glanzmann thrombasthenia (GT) is an autosomal recessive disorder in which the platelet (PLT) glycoprotein IIb/IIIa complex is either deficient or dysfunctional. In its most severe form, GT may result in spontaneous bleeding, although most cases are first detected in the setting of an invasive procedure. CASE REPORT: A 59-year-old male with Type I GT and a history of transfusion reactions to PLT infusions developed severe aortic stenosis secondary to bicuspid valve disease. He successfully underwent open aortic valve replacement with cardiopulmonary bypass without perioperative bleeding complications. RESULTS: A multidisciplinary team (anesthesia, hematology, cardiac surgery, and transfusion medicine) was established to optimize perioperative hematologic management. Bleeding risk was assessed given the patient's prior history and a dosing timeline for administration of blood products and recombinant clotting factors was established. Successful management was achieved during the operation by prophylactic administration of HLA-matched PLTs and Factor VIIa. Prophylactic PLT administration was continued through the immediate postoperative period and no bleeding complications occurred. Thromboelastograms (TEGs) were used in conjunction with traditional hematologic laboratory analysis to optimize clinical management. CONCLUSION: Patients with GT requiring cardiac surgical procedures are at high risk for perioperative bleeding complications. This case report illustrates the importance of multidisciplinary planning, TEG analysis, and the judicious use of recombinant factors to minimize operative bleeding risk.

    View details for DOI 10.1111/trf.12275

    View details for Web of Science ID 000331382100009

  • Surgical reconstruction of peripheral pulmonary artery stenosis in Williams and Alagille syndromes JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Monge, M. C., Mainwaring, R. D., Sheikh, A. Y., Punn, R., Reddy, V. M., Hanley, F. L. 2013; 145 (2): 476-481


    Peripheral pulmonary artery stenosis is a rare congenital heart defect frequently found in association with Williams and Alagille syndromes. Controversy exists regarding the optimal treatment of peripheral pulmonary artery stenosis, with most centers favoring catheter-based interventions. In contrast, we have preferentially used surgical reconstruction of peripheral pulmonary artery stenosis. The purpose of the present study was to review our experience with surgical reconstruction of peripheral pulmonary artery stenosis.We performed a retrospective review of patients who underwent surgical reconstruction of peripheral pulmonary artery stenosis. A total of 16 patients were identified: 7 had Williams syndrome, 6 had Alagille syndrome, and 3 had no identifiable syndrome. Detailed pulmonary angiography was performed in all patients to define stenoses at the main, branch, lobar, and segmental arterial levels. The mean preoperative right ventricular/left ventricular pressure ratio was 0.88 ± 0.07. The surgical approach was a median sternotomy with cardiopulmonary bypass. All peripheral stenoses were augmented with pulmonary artery homograft tissue. The median age at surgery was 14 months, and concomitant procedures were performed in 9 of the 16 patients.There was 1 operative mortality (6%). The mean right ventricular/left ventricular pressure ratio decreased to 0.40 ± 0.04 postoperatively (P < .005), representing a 55% reduction compared with the preoperative values. The patients were followed up for a median of 5 years. No late mortality occurred and reoperation was not required.The data have demonstrate that this comprehensive surgical approach to the treatment of peripheral pulmonary artery stenosis was associated with low early and no late mortality. Surgical reconstruction of the peripheral pulmonary artery stenosis resulted in a significant decrease in right ventricular pressure. We hypothesize that this reduction in right ventricular pressures will confer a long-term survival advantage for this cohort of patients.

    View details for DOI 10.1016/j.jtcvs.2012.09.102

    View details for Web of Science ID 000313634700030

  • RevaTen platelet-rich plasma improves cardiac function after myocardial injury. Cardiovascular revascularization medicine : including molecular interventions Mishra, A., Velotta, J., Brinton, T. J., Wang, X., Chang, S., Palmer, O., Sheikh, A., Chung, J., Yang, P. C., Robbins, R., Fischbein, M. 2011; 12 (3): 158-163


    Cell therapy is an exciting area of investigation for repair of injured myocardial tissue. Platelet-rich plasma (PRP) is an autologous fractionation of whole blood containing high concentrations of growth factors including vascular endothelial growth factor and insulin-like growth factor, among many others. PRP has been shown to safely and effectively enhance healing of musculoskeletal tissue primarily by reparative cell signaling. Despite a growing body of evidence on PRP's safety and efficacy, limited studies have been performed using PRP in cardiovascular tissues. Utilizing a murine myocardial permanent ligation and ischemia/reperfusion model, this study sought to determine whether RevaTen PRP (Menlo Park, CA, USA), a proprietary formulation of PRP, improves cardiac function as measured by left ventricular ejection fraction (LVEF).Via thoracotomy, the left anterior descending arteries (LAD) of 28 mice were occluded by suture either permanently or for 45 min to induce ischemic injury and then reperfused. Mice undergoing permanent ligation had intramyocardial injections of either RevaTen PRP (n=5) or phosphate-buffered saline (PBS; n=4). Magnetic resonance (MR) imaging was performed to calculate LVEF at 7 days. Mice undergoing ischemia and reperfusion had intramyocardial injections of either PRP (n=10) or PBS (n=9) and underwent MR imaging to calculate LVEF at 21 days. Hearts were harvested for histologic examination following imaging.Compared with PBS controls, RevaTen PRP-treated animals that underwent LAD ligation had a 38% higher LVEF 7 days after injury (PRP=36.1±6.1%; PBS=26.4±3.6%, P=.027). Compared with PBS controls, PRP-treated animals who underwent ischemia-reperfusion of the LAD had a 28% higher LVEF 21 days after injury (PRP=37.6±4.8%, control=29.3±9.7%, P=.038). Histologic analysis suggested the presence of more scar tissue in the control group compared to the PRP-treated animals.MR imaging demonstrated a positive effect of RevaTen PRP on left ventricular function in both a ligation and ischemia-reperfusion murine model. Our results suggest RevaTen PRP should be investigated further as a potential point-of-care biologic treatment following myocardial injury.

    View details for DOI 10.1016/j.carrev.2010.08.005

    View details for PubMedID 21122486

  • What are the Predictors that Affect the Excellent Long-term Benefits of Redo Coronary Artery Bypass Grafting? HEART LUNG AND CIRCULATION Ali, A., Ramoutar, D., Ashrafian, H., Abu-Omar, Y., Freed, D., Sheikh, A. Y., Ali, Z., Athanasiou, T., Wallwork, J. 2010; 19 (9): 528-534


    Recurrent angina refractory to medical therapy in patients having undergone prior coronary artery bypass grafting (CABG) is an indication for repeat surgical revascularisation. The primary aim of this retrospective study was to determine the benefit of redo surgery over the longer term with regards to survival and freedom from cardiac symptoms/events. Our secondary aim was to identify risk factors that compromise surgical efficacy of redo revascularisation.Patients were identified through case note review. Survivors were interviewed by telephone according to a defined protocol. Actuarial freedom from cardiac symptoms/events and survival were determined. A composite outcome for cardiac symptoms/events was used and defined as angina class> or =2 or NYHA> or =2 or myocardial infarction or need for percutaneous intervention. Univariate and multivariate analysis was performed. Survival was assessed using a Kaplan-Meier method, and determinants of survival with the Cox proportional hazards model.Between January 1st, 1996 and February 1st, 2004, 101 consecutive patients underwent redo CABG at our institution under the care of a single surgeon. There were 91 men and 10 women, 64% (65/101) had an age> or =70 years. 30-Day mortality was 1.2% (2/101). Mean time to follow-up was 5.3+/-3.8 years. Poor left ventricular function and pre-operative NYHA> or =2 status were independent predictors of decreased survival with hazard ratios (HR) of 2.12 (1.042-4.31) and 3.98 (1.39-11.39) respectively. The use of a radial artery graft at re-operation was an independent predictor of peri-operative death OR=18 (1-346). Actuarial survival at 1, 5 and 8 years was 90.1%, 84.4% and 76.9% and freedom from cardiac symptoms/events was 100%, 95% and 68% respectively.This study shows acceptable short- and long-term survival and freedom from symptoms/events in patients undergoing redo coronary artery bypass grafting at a single institution. The apparent association between radial arterial grafts and impaired early clinical outcome warrants further investigation.

    View details for DOI 10.1016/j.h1c.2010.02.028

    View details for Web of Science ID 000281329000004

    View details for PubMedID 20418162

  • Stentless aortic valve replacement in patients with bicuspid aortic valve disease: clinical outcome and aortic diameter changes during follow-up EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY Ali, A., Patel, A., Ali, Z. A., Abu-Omar, Y., Freed, D., Sheikh, A. Y., Athanasiou, T., Pepper, J. 2010; 38 (2): 134-140


    A bicuspid aortic valve (BAV) may be associated with an aortopathy affecting clinical outcome. Our aim was to assess long-term outcome and analyse if progressive aortic dilatation occurs with time in patients with BAV disease who underwent stentless valve replacement.Demographic, operative and clinical data were retrospectively reviewed. Patients were classified according to whether their native aortic valve was identified as tricuspid (TC) or bicuspid (BC) at the time of AVR. Serial transthoracic echocardiography was used to measure changes in ascending aortic diameter over time. Propensity adjustment and multivariate regression were used. Events over time were assessed using the Kaplan-Meier method, and the determinants of events were assessed with the Cox proportional-hazards model.Between January 1991 and January 2001, 215 patients underwent AVR. They had a serial follow-up echocardiography performed for a mean of 6.1+/-4.3 years postoperatively. Ninety patients (41%) had a BAV, and the BC group was younger (BC 62+/-15 years vs TC 71+/-12 years; p=0.002). We found no difference in the increase in ascending aortic diameter over follow-up (BC 0.1+/-0.5 cm vs TC 0.0+/-0.5 cm; p=0.34). BC morphology was not an independent predictor of increased overall mortality (propensity-adjusted hazard ratio: 0.79; 95% confidence interval (CI): 0.42-1.44; p=0.44) or increased risk of reoperation (propensity adjusted hazard ration: 1.84; 95% CI: 0.88-3.36; p=0.11).Stentless AVR is protective against progressive aortic aneurysmal disease and confers excellent clinical outcomes in patients with BAV and normal preoperative ascending aortic diameter.

    View details for DOI 10.1016/j.ejcts.2010.01.039

    View details for Web of Science ID 000280941200003

    View details for PubMedID 20227289

  • Indirect imaging of cardiac-specific transgene expression using a bidirectional two-step transcriptional amplification strategy GENE THERAPY Chen, I. Y., Gheysens, O., Ray, S., Wang, Q., Padmanabhan, P., Paulmurugan, R., Loening, A. M., Rodriguez-Porcel, M., Willmann, J. K., Sheikh, A. Y., Nielsen, C. H., Hoyt, G., Contag, C. H., Robbins, R. C., Biswal, S., Wu, J. C., Gambhir, S. S. 2010; 17 (7): 827-838


    Transcriptional targeting for cardiac gene therapy is limited by the relatively weak activity of most cardiac-specific promoters. We have developed a bidirectional plasmid vector, which uses a two-step transcriptional amplification (TSTA) strategy to enhance the expression of two optical reporter genes, firefly luciferase (fluc) and Renilla luciferase (hrluc), driven by the cardiac troponin T (cTnT) promoter. The vector was characterized in vitro and in living mice using luminometry and bioluminescence imaging to assess its ability to mediate strong, correlated reporter gene expression in a cardiac cell line and the myocardium, while minimizing expression in non-cardiac cell lines and the liver. In vitro, the TSTA system significantly enhanced cTnT-mediated reporter gene expression with moderate preservation of cardiac specificity. After intramyocardial and hydrodynamic tail vein delivery of an hrluc-enhanced variant of the vector, long-term fluc expression was observed in the heart, but not in the liver. In both the cardiac cell line and the myocardium, fluc expression correlated well with hrluc expression. These results show the vector's ability to effectively amplify and couple transgene expression in a cardiac-specific manner. Further replacement of either reporter gene with a therapeutic gene should allow non-invasive imaging of targeted gene therapy in living subjects.

    View details for DOI 10.1038/gt.2010.30

    View details for Web of Science ID 000279614600002

    View details for PubMedID 20237511

  • Micro-CT for Characterization of Murine CV Disease Models JACC-CARDIOVASCULAR IMAGING Sheikh, A. Y., van der Bogt, K. E., Doyle, T. C., Sheikh, M. K., Ransohoff, K. J., Ali, Z. A., Palmer, O. P., Robbins, R. C., Fischbein, M. P., Wu, J. C. 2010; 3 (7): 783-785

    View details for DOI 10.1016/j.jcmg.2010.01.012

    View details for Web of Science ID 000281626700015

    View details for PubMedID 20633858

  • Endogenous regulation of cardiovascular function by apelin-APJ AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Charo, D. N., Ho, M., Fajardo, G., Kawana, M., Kundu, R. K., Sheikh, A. Y., Finsterbach, T. P., Leeper, N. J., Ernst, K. V., Chen, M. M., Ho, Y. D., Chun, H. J., Bernstein, D., Ashley, E. A., Quertermous, T. 2009; 297 (5): H1904-H1913


    Studies have shown significant cardiovascular effects of exogenous apelin administration, including the potent activation of cardiac contraction. However, the role of the endogenous apelin-APJ pathway is less clear. To study the loss of endogenous apelin-APJ signaling, we generated mice lacking either the ligand (apelin) or the receptor (APJ). Apelin-deficient mice were viable, fertile, and showed normal development. In contrast, APJ-deficient mice were not born in the expected Mendelian ratio, and many showed cardiovascular developmental defects. Under basal conditions, both apelin and APJ null mice that survived to adulthood manifested modest decrements in contractile function. However, with exercise stress both mutant lines demonstrated consistent and striking decreases in exercise capacity. To explain these findings, we explored the role of autocrine signaling in vitro using field stimulation of isolated left ventricular cardiomyocytes lacking either apelin or APJ. Both groups manifested less sarcomeric shortening and impaired velocity of contraction and relaxation with no difference in calcium transient. Taken together, these results demonstrate that endogenous apelin-APJ signaling plays a modest role in maintaining basal cardiac function in adult mice with a more substantive role during conditions of stress. In addition, an autocrine pathway seems to exist in myocardial cells, the ablation of which reduces cellular contraction without change in calcium transient. Finally, differences in the developmental phenotype between apelin and APJ null mice suggest the possibility of undiscovered APJ ligands or ligand-independent effects of APJ.

    View details for DOI 10.1152/ajpheart.00686.2009

    View details for Web of Science ID 000271143400045

    View details for PubMedID 19767528

  • Postpericardiotomy syndrome from transdiaphragmatic pericardial window following trauma: first description and review of the literature JOURNAL OF CARDIOVASCULAR MEDICINE King, D. R., Vlahakes, G. J., Johri, A. M., Sheikh, A. Y. 2009; 10 (10): 806-809


    Diagnostic pericardial window (by either subxyphoid or transdiaphragmatic approach) is commonly utilized to exclude traumatic cardiac injury. Although regarded as a low-risk procedure, rare complications such as bacterial pericarditis, iatrogenic cardiac injury, cardiac herniation and postpericardiotomy syndrome can occur. We report the first description of postpericardiotomy syndrome following transdiaphragmatic pericardial window.

    View details for DOI 10.2459/JCM.0b013e32832d7239

    View details for Web of Science ID 000270046400014

    View details for PubMedID 19606058

  • Right Atrial Mass: The Dilemma of Diagnosis and When Not to Operate Reply ANNALS OF THORACIC SURGERY Sheikh, A. Y., Pelletier, M. P. 2009; 87 (6): 2005-2005
  • Comparison of Optical Bioluminescence Reporter Gene and Superparamagnetic Iron Oxide MR Contrast Agent as Cell Markers for Noninvasive Imaging of Cardiac Cell Transplantation MOLECULAR IMAGING AND BIOLOGY Chen, I. Y., Greve, J. M., Gheysens, O., Willmann, J. K., Rodriguez-Porcel, M., Chu, P., Sheikh, A. Y., Faranesh, A. Z., Paulmurugan, R., Yang, P. C., Wu, J. C., Gambhir, S. S. 2009; 11 (3): 178-187


    In this study, we compared firefly luciferase (Fluc) reporter gene and superparamagnetic iron oxide (Feridex) as cell markers for longitudinal monitoring of cardiomyoblast graft survival using optical bioluminescence imaging (BLI) and magnetic resonance imaging (MRI), respectively.Rats (n = 31) underwent an intramyocardial injection of cardiomyoblasts (2 x 10(6)) labeled with Fluc, Feridex, or no marker (control) or an injection of Feridex alone (75 microg). Afterward, rats were serially imaged with BLI or MRI and killed at different time points for histological analysis.BLI revealed a drastically different cell survival kinetics (half-life = 2.65 days over 6 days) than that revealed by MRI (half-life = 16.8 days over 80 days). Injection of Feridex alone led to prolonged tissue retention of Feridex (> or =16 days) and persistent MR signal (> or =42 days).Fluc BLI reporter gene imaging is a more accurate gauge of transplanted cell survival as compared to MRI of Feridex-labeled cells.

    View details for DOI 10.1007/s11307-008-0182-z

    View details for Web of Science ID 000265686900005

    View details for PubMedID 19034584

  • Comparison of Transplantation of Adipose Tissue- and Bone Marrow-Derived Mesenchymal Stem Cells in the Infarcted Heart TRANSPLANTATION van der Bogt, K. E., Schrepfer, S., Yu, J., Sheikh, A. Y., Hoyt, G., Govaert, J. A., Velotta, J. B., Contag, C. H., Robbins, R. C., Wu, J. C. 2009; 87 (5): 642-652


    Mesenchymal stem cells hold promise for cardiovascular regenerative therapy. Derivation of these cells from the adipose tissue might be easier compared with bone marrow. However, the in vivo fate and function of adipose stromal cells (ASC) in the infarcted heart has never been compared directly to bone marrow-derived mesenchymal cells (MSC).ASC and MSC were isolated from transgenic FVB mice with a beta-actin promoter driving firefly luciferase and green fluorescent protein double fusion reporter gene, and they were characterized using flow cytometry, microscopy, bioluminescence imaging and luminometry. FVB mice (n=8 per group) underwent myocardial infarction followed by intramyocardial injection of 5x10(5) ASC, MSC, fibroblasts (Fibro, positive control), or saline (negative control). Cell survival was measured using bioluminescence imaging for 6 weeks and cardiac function was monitored by echocardiography and pressure-volume analysis. Ventricular morphology was assessed using histology.ASC and MSC were CD34(-), CD45(-), c-Kit(-), CD90(+), Sca-1(+), shared similar morphology and had a population doubling time of approximately 2 days. Cells expressed Fluc reporter genes in a number-dependent fashion as confirmed by luminometry. After cardiac transplantation, both cell types showed drastic donor cell death within 4 to 5 weeks. Furthermore, transplantation of either cell type was not capable of preserving ventricular function and dimensions, as confirmed by pressure-volume-loops and histology.This is the first study comparing the in vivo behavior of both cell types in the infarcted heart. ASC and MSC do not tolerate well in the cardiac environment, resulting in acute donor cell death and a subsequent loss of cardiac function similar to control groups.

    View details for DOI 10.1097/TP.0b013e31819609d9

    View details for Web of Science ID 000264146100005

    View details for PubMedID 19295307

  • Propensity analysis of survival after subcoronary or root replacement techniques for homograft aortic valve replacement JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Ali, A., Abu-Omar, Y., Patel, A., Sheikh, A. Y., Ali, Z., Saeed, A., Akhtar, A., Athanasiou, T., Pepper, J. 2009; 137 (2): 334-341


    Homograft aortic valve replacement is associated with excellent clinical and hemodynamic outcomes. Valves are implanted predominantly by using 2 techniques: the freehand subcoronary technique or as an aortic root replacement. Our aim was to identify any difference in survival, durability, and clinical performance.Demographic, operative, and clinical data were obtained retrospectively through case-note review. All operations were performed by a single surgeon. Propensity score-adjusted analysis was used by developing a nonparsimonious logistic regression model for implantation with subcoronary versus root replacement. Actuarial survival and freedom from valve-related events were compared with Kaplan-Meier curves and multivariable proportional hazard Cox regression.Between January 1, 1991, and January 1, 2001, 215 patients underwent aortic valve replacement with a homograft. The subcoronary technique was used in 131 (61%) patients. Eighty-four (39%) patients underwent free-standing aortic root replacement. After propensity risk adjustment, the subcoronary implantation technique was associated with a decreased risk of 30-day death (adjusted odds ratio, 0.18; 95% confidence interval, 0.06-0.34; P = .03). Technique of insertion was not an independent predictor of overall mortality during follow-up after adjustment (propensity adjusted hazard ratio, 0.35; 95% confidence interval, 0.09-1.41; P = .18). There were no significant differences in 1- and 5-year actuarial survival, freedom from structural valve disease, endocarditis, or reoperation.Both the subcoronary and root replacement techniques for homograft aortic valve replacement are associated with excellent midterm survival and clinical performance. Root replacement was associated with an increased risk of perioperative death after adjustment for covariates by using propensity analysis.

    View details for DOI 10.1016/j.jtcvs.2008.10.015

    View details for Web of Science ID 000262919000012

    View details for PubMedID 19185147

  • Apelin signaling antagonizes Ang II effects in mouse models of atherosclerosis JOURNAL OF CLINICAL INVESTIGATION Chun, H. J., Ali, Z. A., Kojima, Y., Kundu, R. K., Sheikh, A. Y., Agrawal, R., Zheng, L., Leeper, N. J., Pearl, N. E., Patterson, A. J., Anderson, J. P., Tsao, P. S., Lenardo, M. J., Ashley, E. A., Quertermous, T. 2008; 118 (10): 3343-3354


    Apelin and its cognate G protein-coupled receptor APJ constitute a signaling pathway with a positive inotropic effect on cardiac function and a vasodepressor function in the systemic circulation. The apelin-APJ pathway appears to have opposing physiological roles to the renin-angiotensin system. Here we investigated whether the apelin-APJ pathway can directly antagonize vascular disease-related Ang II actions. In ApoE-KO mice, exogenous Ang II induced atherosclerosis and abdominal aortic aneurysm formation; we found that coinfusion of apelin abrogated these effects. Similarly, apelin treatment rescued Ang II-mediated increases in neointimal formation and vascular remodeling in a vein graft model. NO has previously been implicated in the vasodepressor function of apelin; we found that apelin treatment increased NO bioavailability in ApoE-KO mice. Furthermore, infusion of an NO synthase inhibitor blocked the apelin-mediated decrease in atherosclerosis and aneurysm formation. In rat primary aortic smooth muscle cells, apelin inhibited Ang II-mediated transcriptional regulation of multiple targets as measured by reporter assays. In addition, we demonstrated by coimmunoprecipitation and fluorescence resonance energy transfer analysis that the Ang II and apelin receptors interacted physically. Taken together, these findings indicate that apelin signaling can block Ang II actions in vascular disease by increasing NO production and inhibiting Ang II cellular signaling.

    View details for DOI 10.1172/JCI34871

    View details for Web of Science ID 000259828600016

    View details for PubMedID 18769630

  • Multimodal evaluation of in vivo magnetic resonance imaging of myocardial restoration by mouse embryonic stem cells JOURNAL OF THORACIC AND CARDIOVASCULAR SURGERY Hendry, S. L., van der Bogt, K. E., Sheikh, A. Y., Arai, T., Dylla, S. J., Drukker, M., McConnell, M. V., Kutschka, I., Hoyt, G., Cao, F., Weissman, I. L., Connolly, A. J., Pelletier, M. P., Wu, J. C., Robbins, R. C., Yang, P. C. 2008; 136 (4): 1028-U14


    Mouse embryonic stem cells have demonstrated potential to restore infarcted myocardium after acute myocardial infarction. Although the underlying mechanism remains controversial, magnetic resonance imaging has provided reliable in vivo assessment of functional recovery after cellular transplants. Multimodal comparison of the restorative effects of mouse embryonic stem cells and mouse embryonic fibroblasts was performed to validate magnetic resonance imaging data and provide mechanistic insight.SCID-beige mice (n = 55) underwent coronary artery ligation followed by injection of 2.5 x 10(5) mouse embryonic stem cells, 2.5 x 10(5) mouse embryonic fibroblasts, or normal saline solution. In vivo magnetic resonance imaging of myocardial restoration by mouse embryonic stem cells was evaluated by (1) in vivo pressure-volume loops, (2) in vivo bioluminescence imaging, and (3) ex vivo TaqMan (Roche Molecular Diagnostics, Pleasanton, Calif) polymerase chain reaction and immunohistologic examination.In vivo magnetic resonance imaging demonstrated significant improvement in left ventricular ejection fraction at 1 week in the mouse embryonic stem cell group. This finding was validated with (1) pressure-volume loop analysis demonstrating significantly improved systolic and diastolic functions, (2) bioluminescence imaging and polymerase chain reaction showing superior posttransplant survival of mouse embryonic stem cells, (3) immunohistologic identification of cardiac phenotype within engrafted mouse embryonic stem cells, and (4) polymerase chain reaction measuring increased expressions of angiogenic and antiapoptotic genes and decreased expressions of antifibrotic genes.This study validates in vivo magnetic resonance imaging as an effective means of evaluating the restorative potential of mouse embryonic stem cells.

    View details for DOI 10.1016/j.jtcvs.2007.12.053

    View details for Web of Science ID 000260314800033

    View details for PubMedID 18954646

  • Comparison of different adult stem cell types for treatment of myocardial ischemia CIRCULATION van der Bogt, K. E., Sheikh, A. Y., Schrepfer, S., Hoyt, G., Cao, F., Ransohoff, K. J., Swijnenburg, R., Pearl, J., Lee, A., Fischbein, M., Contag, C. H., Robbins, R. C., Wu, J. C. 2008; 118 (14): S121-U166


    A comparative analysis of the efficacy of different cell candidates for the treatment of heart disease remains to be described. This study is designed to evaluate the therapeutic efficacy of 4 cell types in a murine model of myocardial infarction.Bone marrow mononuclear cells (MN), mesenchymal stem cells (MSC), skeletal myoblasts (SkMb), and fibroblasts (Fibro) expressing firefly luciferase (Fluc) and green fluorescence protein (GFP) were characterized by flow cytometry, bioluminescence imaging (BLI), and luminometry. Female FVB mice (n=70) underwent LAD ligation and intramyocardially received one cell type (5x10(5)) or PBS. Cell survival was measured by BLI and by TaqMan PCR. Cardiac function was assessed by echocardiography and invasive hemodynamic measurements. Fluc expression correlated with cell number in all groups (r(2)>0.93). In vivo BLI revealed acute donor cell death of MSC, SkMb, and Fibro within 3 weeks after transplantation. By contrast, cardiac signals were still present after 6 weeks in the MN group, as confirmed by TaqMan PCR (P<0.01). Echocardiography showed significant preservation of fractional shortening in the MN group compared to controls (P<0.05). Measurements of left ventricular end-systolic/diastolic volumes revealed that the least amount of ventricular dilatation occurred in the MN group (P<0.05). Histology confirmed the presence of MN, although there was no evidence of transdifferentiation by donor MN into cardiomyocytes.This is the first study to show that compared to MSC, SkMB, and Fibro, MN exhibit a more favorable survival pattern, which translates into a more robust preservation of cardiac function.

    View details for DOI 10.1161/CIRCULATIONAHA.107.759480

    View details for Web of Science ID 000259648600018

    View details for PubMedID 18824743

  • Immunosuppressive therapy mitigates immunological rejection of human embryonic stem cell xenografts PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Swijnenburg, R., Schrepfer, S., Govaert, J. A., Cao, F., Ransohoff, K., Sheikh, A. Y., Haddad, M., Connolly, A. J., Davis, M. M., Robbins, R. C., Wu, J. C. 2008; 105 (35): 12991-12996


    Given their self-renewing and pluripotent capabilities, human embryonic stem cells (hESCs) are well poised as a cellular source for tissue regeneration therapy. However, the host immune response against transplanted hESCs is not well characterized. In fact, controversy remains as to whether hESCs have immune-privileged properties. To address this issue, we used in vivo bioluminescent imaging to track the fate of transplanted hESCs stably transduced with a double-fusion reporter gene consisting of firefly luciferase and enhanced GFP. We show that survival after transplant is significantly limited in immunocompetent as opposed to immunodeficient mice. Repeated transplantation of hESCs into immunocompetent hosts results in accelerated hESC death, suggesting an adaptive donor-specific immune response. Our data demonstrate that transplanted hESCs trigger robust cellular and humoral immune responses, resulting in intragraft infiltration of inflammatory cells and subsequent hESC rejection. Moreover, we have found CD4(+) T cells to be an important modulator of hESC immune-mediated rejection. Finally, we show that immunosuppressive drug regimens can mitigate the anti-hESC immune response and that a regimen of combined tacrolimus and sirolimus therapies significantly prolongs survival of hESCs for up to 28 days. Taken together, these data suggest that hESCs are immunogenic, trigger both cellular and humoral-mediated pathways, and, as a result, are rapidly rejected in xenogeneic hosts. This process can be mitigated by a combined immunosuppressive regimen as assessed by molecular imaging approaches.

    View details for DOI 10.1073/pnas.0805802105

    View details for Web of Science ID 000259343000067

    View details for PubMedID 18728188

  • Multimodality Evaluation of the Viability of Stem Cells Delivered Into Different Zones of Myocardial Infarction CIRCULATION-CARDIOVASCULAR IMAGING Hung, T., Suzuki, Y., Urashima, T., Caffarelli, A., Hoyt, G., Sheikh, A. Y., Yeung, A. C., Weissman, I., Robbins, R. C., Bulte, J. W., Yang, P. C. 2008; 1 (1): 6-13


    We tested the hypothesis that multimodality imaging of mouse embryonic stem cells (mESCs) provides accurate assessment of cellular location, viability, and restorative potential after transplantation into different zones of myocardial infarction.Mice underwent left anterior descending artery ligation followed by transplantation of dual-labeled mESCs with superparamagnetic iron oxide and luciferase via direct injection into 3 different zones of myocardial infarction: intra-infarction, peri-infarction, and normal (remote). One day after transplantation, magnetic resonance imaging enabled assessment of the precise anatomic locations of mESCs. Bioluminescence imaging allowed longitudinal analysis of cell viability through detection of luciferase activity. Subsequent evaluation of myocardial regeneration and functional restoration was performed by echocardiography and pressure-volume loop analysis. Using 16-segment analysis, we demonstrated precise localization of dual-labeled mESCs. A strong correlation between histology and magnetic resonance imaging was established (r=0.962, P=0.002). Bioluminescent imaging data demonstrated that cell viability in the remote group was significantly higher than in other groups. Echocardiography and pressure-volume loop analysis revealed improved functional restoration in animals treated with mESCs, although myocardial regeneration was not observed.Multimodality evaluation of mESC engraftment in the heterogeneous tissue of myocardial infarction is possible. Magnetic resonance imaging demonstrated accurate anatomic localization of dual-labeled mESCs. Bioluminescent imaging enabled assessment of variable viability of mESCs transplanted into the infarcted myocardium. Echocardiography and pressure-volume loop analysis validated the restorative potential of mESCs. Although mESCs transplanted into the remote zone demonstrated the highest viability, precise delivery of mESCs into the peri-infarction region might be equally critical in restoring the injured myocardium.

    View details for DOI 10.1161/CIRCIMAGING.108.767343

    View details for Web of Science ID 000266039600003

    View details for PubMedID 19808509

  • Multimodal imaging characterization of intracardiac thrombus and myxoma - Reply ANNALS OF THORACIC SURGERY Sheikh, A. Y., Pelletier, M. P. 2008; 85 (6): 2162-2163
  • Valve failure following homograft aortic valve replacement: does implantation technique have an effect? EUROPEAN HEART JOURNAL Ali, A., Abu-Omar, Y., Patel, A., Ali, Z., Sheikh, A. Y., Akhtar, A., Pavlovic, A., Theodorou, P., Athanasiou, T., Pepper, J. 2008; 29 (11): 1454-1462


    Structural valve deterioration (SVD) limits the long-term durability of homograft aortic valve replacement (AVR). Valves are implanted predominantly using two techniques, the free-hand sub-coronary (SC) technique or aortic root replacement (RR). Our objective was to identify risk factors associated with the development of SVD or ascending aortic dilatation. In particular we strived to determine whether the mode of implantation had an independent effect.Demographic and pre-operative clinical data were obtained retrospectively through case-note review. All operations were performed by a single surgeon. Actuarial freedom from >or=2+ AR (aortic regurgitation), elevated trans-valvular gradient (TVG) (>or=25 mmHg) and ascending aortic dilatation (>or=4.0 cm) were assessed using Kaplan-Meier curves and multivariable Cox proportional hazards regression. A propensity analysis was carried out using a non-parsimonius logistic regression model for implantation with SC vs. RR. Between 1 January 1991 and 1 January 2001, 215 patients underwent AVR with a homograft. The SC technique was used in 131 (61%) patients and 84 (39%) patients underwent RR. Technique was not an independent predictor for >or=2+ AR (adjusted hazard ratio 1.9; 95% CI 0.56-6.16, P = 0.31), elevated TVG (adjusted hazard ratio; 0.99; 95% CI 0.15-6.71, P = 0.99) or ascending aortic dilatation (adjusted hazard ratio 2.01; 95% CI 0.50-8.25, P = 0.33). One and 5 year actuarial freedom from >or=2+ AR (log-rank - P = 0.09) and ascending aortic dilatation (log-rank - P = 0.88) were not significantly different between groups.The incidence of SVD and ascending aortic dilatation is not affected by the method of implantation of the aortic homograft. All homografts are prone to SVD which is responsible for a progressive increase in the prevalence of these changes over time.

    View details for DOI 10.1093/eurheartj/ehn174

    View details for Web of Science ID 000256518100021

    View details for PubMedID 18456709

  • Perioperative myocardial injury after elective open abdominal aortic aneurysm repair predicts outcome EUROPEAN JOURNAL OF VASCULAR AND ENDOVASCULAR SURGERY Ali, Z. A., Callaghan, C. J., Ali, A. A., Sheikh, A. Y., Akhtar, A., Pavlovic, A., Nouraei, S. A., Dutka, D. P., Gaunt, M. E. 2008; 35 (4): 413-419


    Myocardial injury, detected by rises in cardiac troponin I (TnI), is common and associated with decreased survival following open AAA surgery. We examined the relationship between perioperative myocardial injury and postoperative outcome.Observational Cohort Study.Forty-three consecutive patients who underwent elective open AAA repair were screened for perioperative myocardial injury or infarction using serial TnI measurements (taken on days 1, 3, and 7), ECG and clinical assessment. The primary outcome was survival free of cardiac failure, or myocardial infarction (MI) at follow-up.Twenty (47%) of the 43 patients had a TnI elevation. Of these, 11 (26%) patients met the criteria for MI. At a mean (+/-SD) follow-up of 1.5+/-0.8 years, 12 (28%) subjects had experienced at least one endpoint event. Survival free of cardiac failure or MI was 55% in patients who had TnI rises compared to 87% in those without (P=0.02). Logistic regression revealed that TnI elevation was an independent predictor of outcome with an odds ratio of 5.4 (95% CI 1.2-2.4, P=0.03).Perioperative myocardial injury after elective open AAA repair predicts outcome after surgery. Routine TnI measurement should be considered in all patients, especially in those with high cardiovascular risk.

    View details for DOI 10.1016/j.ejvs.2007.10.007

    View details for Web of Science ID 000254993100005

    View details for PubMedID 18063394

  • Smooth muscle protein 22 alpha-mediated patchy deletion of Bmpr1a impairs cardiac contractility but protects against pulmonary vascular remodeling CIRCULATION RESEARCH El-Bizri, N., Wang, L., Merklinger, S. L., Guignabert, C., Desai, T., Urashima, T., Sheikh, A. Y., Knutsen, R. H., Mecham, R. P., Mishina, Y., Rabinovitch, M. 2008; 102 (3): 380-388


    Vascular expression of bone morphogenetic type IA receptor (Bmpr1a) is reduced in lungs of patients with pulmonary arterial hypertension, but the significance of this observation is poorly understood. To elucidate the role of Bmpr1a in the vascular pathology of pulmonary arterial hypertension and associated right ventricular (RV) dysfunction, we deleted Bmpr1a in vascular smooth muscle cells and in cardiac myocytes in mice using the SM22alpha;TRE-Cre/LoxP;R26R system. The LacZ distribution reflected patchy deletion of Bmpr1a in the lung vessels, aorta, and heart of SM22alpha;TRE-Cre;R26R;Bmpr1a(flox/+) and flox/flox mutants. This reduction in BMPR-IA expression was confirmed by Western immunoblot and immunohistochemistry in the flox/flox group. This did not affect pulmonary vasoreactivity to acute hypoxia (10% O2) or the increase in RV systolic pressure and RV hypertrophy following 3 weeks in chronic hypoxia. However, both SM22alpha;TRE-Cre;R26R;Bmpr1a(flox/+) and flox/flox mutant mice had fewer muscularized distal pulmonary arteries and attenuated loss of peripheral pulmonary arteries compared with age-matched control littermates in hypoxia. When Bmpr1a expression was reduced by short interference RNA in cultured pulmonary arterial smooth muscle cells, serum-induced proliferation was attenuated explaining decreased hypoxia-mediated muscularization of distal vessels. When Bmpr1a was reduced in cultured microvascular pericytes by short interference RNA, resistance to apoptosis was observed and this could account for protection against hypoxia-mediated vessel loss. The similar elevation in RV systolic pressure and RV hypertrophy, despite the attenuated remodeling with chronic hypoxia in the flox/flox mutants versus controls, was not a function of elevated left ventricular end diastolic pressure but was associated with increased periadventitial deposition of elastin and collagen, potentially influencing vascular stiffness.

    View details for DOI 10.1161/CIRCRESAHA.107.161059

    View details for Web of Science ID 000253194600018

    View details for PubMedID 18079409

  • A novel platform device for rodent echocardiography. ILAR journal Kutschka, I., Sheikh, A. Y., Sista, R., Hendry, S. L., Chun, H. J., Hoyt, G., Kutschka, W., Pelletier, M. P., Quertermous, T., Wu, J. C., Robbins, R. C. 2008; 49: E1-7


    Acquisition of echocardiographic data from rodents is subject to wide variability due to variations in technique. We hypothesize that a dedicated imaging platform can aid in standardization of technique and improve the quality of images obtained. We constructed a device consisting of a boom-mounted steel platform frame (25 x 35 x 3 cm) on which a transparent polyethylene membrane is mounted. The animal is placed onto the membrane and receives continual inhaled anesthesia via an integrated port. The membrane allows for probe positioning from beneath the animal to obtain standard echo-views in left lateral decubitus or prone positions. The frame can be set at any desired angle ranging from 0 to 360 degrees along either the long or short axis. Adult male Sprague-Dawley rats (n = 5) underwent echocardiography (General Electric, Vivid 7, 14 MHz) using the platform. The device allowed for optimal positioning of animals for a variety of standard echocardiographic measurements. Evaluations among all animals showed minimal variability between two different operators and time points. We tested the feasibility of the device for supporting the assessment of cardiac function in a disease model by evaluating a separate cohort of adult male spontaneously hypertensive rats (n = 5) that underwent left anterior descending coronary artery ligation. Serial echocardiography demonstrated statistically significant decreases of fractional shortening and ejection fraction (p < 0.01) 240 days after surgery. Our novel imaging platform allowed for consistent collection of high-quality echocardiographic data from rats. Future studies will focus on improving this technology to allow for standardized high-throughput echocardiographic analysis in small animal models of disease.

    View details for PubMedID 18506056

  • In vivo genetic profiling and cellular localization of apelin reveals a hypoxia-sensitive, endothelial-centered pathway activated in ischemic heart failure AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Sheikh, A. Y., Chun, H. J., Glassford, A. J., Kundu, R. K., Kutschka, I., Ardigo, D., Hendry, S. L., Wagner, R. A., Chen, M. M., Ali, Z. A., Yue, P., Huynh, D. T., Connolly, A. J., Pelletier, M. P., Tsao, P. S., Robbins, R. C., Quertermous, T. 2008; 294 (1): H88-H98


    Signaling by the peptide ligand apelin and its cognate G protein-coupled receptor APJ has a potent inotropic effect on cardiac contractility and modulates systemic vascular resistance through nitric oxide-dependent signaling. In addition, there is evidence for counterregulation of the angiotensin and vasopressin pathways. Regulatory stimuli of the apelin-APJ pathway are of obvious importance but remain to be elucidated. To better understand the physiological response of apelin-APJ to disease states such as heart failure and to elucidate the mechanism by which such a response might occur, we have used the murine model of left anterior descending coronary artery ligation-induced ischemic cardiac failure. To identify the key cells responsible for modulation and production of apelin in vivo, we have created a novel apelin-lacZ reporter mouse. Data from these studies demonstrate that apelin and APJ are upregulated in the heart and skeletal muscle following myocardial injury and suggest that apelin expression remains restricted to the endothelium. In cardiac failure, endothelial apelin expression correlates with other hypoxia-responsive genes, and in healthy animals both apelin and APJ are markedly upregulated in various tissues following systemic hypoxic exposure. Experiments with cultured endothelial cells in vitro show apelin mRNA and protein levels to be increased by hypoxia, through a hypoxia-inducible factor-mediated pathway. These studies suggest that apelin-expressing endothelial cells respond to conditions associated with heart failure, possibly including local tissue hypoxia, and modulate apelin-APJ expression to regulate cardiovascular homeostasis. The apelin-APJ pathway may thus provide a mechanism for systemic endothelial monitoring of tissue perfusion and adaptive regulation of cardiovascular function.

    View details for DOI 10.1152/ajpheart.00935.2007

    View details for Web of Science ID 000252261200013

    View details for PubMedID 17906101

  • HIF-1 regulates hypoxia- and insulin-induced expression of apelin in adipocytes AMERICAN JOURNAL OF PHYSIOLOGY-ENDOCRINOLOGY AND METABOLISM Glassford, A. J., Yue, P., Sheikh, A. Y., Chun, H. J., Zarafshar, S., Chan, D. A., Reaven, G. M., Quertermous, T., Tsao, P. S. 2007; 293 (6): E1590-E1596


    Apelin, a novel peptide with significant cardioactive properties, is upregulated by insulin in adipocytes. However, the mechanism by which insulin promotes apelin production is unknown. Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor involved in the angiogenic and metabolic responses to tissue hypoxia, has been shown to be activated by insulin in various settings. We therefore hypothesized that HIF-1 regulates insulin-mediated apelin expression in adipocytes. 3T3-L1 cells were differentiated into adipocytes in culture. For experiments, serum-starved 3T3-L1 cells were exposed to insulin and/or a 1% O(2) environment. Apelin expression was assessed using quantitative real-time PCR and ELISA. To directly assess the role of HIF-1 in apelin production, we differentiated mouse embryonic fibroblasts (MEFs) containing a targeted deletion of the HIF-1alpha gene into adipocytes and measured their response to insulin and hypoxia. Apelin expression in mature 3T3-L1 adipocytes was increased significantly by insulin and was attenuated by pharmacological inhibition of insulin signaling. Exposure of cells to either hypoxia or the chemical HIF activators cobalt chloride (CoCl(2)) and dimethyloxaloylglycine (DMOG) resulted in significant upregulation of apelin, consistent with a role for HIF in apelin induction. Moreover, hypoxia-, CoCl(2)-, DMOG-, and insulin-induced apelin expression were all attenuated in differentiated HIF-1alpha-deficient MEFs. In summary, in cultured 3T3-L1 adipocytes and differentiated MEFs, HIF-1 appears to be involved in hypoxia- and insulin-induced apelin expression.

    View details for DOI 10.1152/ajpendo.00490.2007

    View details for Web of Science ID 000251510200014

    View details for PubMedID 17878221

  • Spatial and temporal kinetics, of teratoma formation from murine embryonic stem cell transplantation STEM CELLS AND DEVELOPMENT Cao, F., van der Bogt, K. E., Sadrzadeh, A., Xie, X., Sheikh, A. Y., Wang, H., Connolly, A. J., Robbins, R. C., Wu, J. C. 2007; 16 (6): 883-891


    Pluripotent embryonic stem (ES) cells have the potential to form teratomas composed of derivatives from all three germ layers in animal models. This tumorigenic potential prevents clinical translation of ES cell research. In order to understand the biology and physiology of teratoma formation, we investigated the influence of undifferentiated ES cell number, migration, and long-term follow up after transplantation. Murine ES cells were stably transduced with a self-inactivating (SIN) lentiviral vector with a constitutive ubiquitin promoter driving a double-fusion (DF) reporter gene that consists of firefly luciferase and enhanced green fluorescent protein (Fluc-eGFP). To assess effects of cell numbers, varying numbers of ES-DF cells (1, 10, 100, 1,000, and 10,000) were injected subcutaneously into the dorsal regions of adult nude mice. To assess cell migration, 1 x 10(6) ES-DF cells were injected intramyocardially into adult Sv129 mice, and leakage to other extracardiac sites was monitored. To assess effects of long-term engraftment, 1 x 10(4) ES-DF cells were injected intramyocardially into adult nude rats, and cell survival response was monitored for 10 months. Our results show that ES-DF cells caused extracardiac teratoma in both immunocompetent and immunodeficient hosts; the lowest number of undifferentiated ES cells capable of causing teratoma was 500-1,000; and long-term engraftment could be shown for >300 days. Collectively, these results illustrate the potent tumorigenic potential of ES cells, which presents an enormous obstacle for future clinical studies.

    View details for DOI 10.1089/scd.2007.0160

    View details for Web of Science ID 000252031000002

    View details for PubMedID 17896868

  • Right atrial mass after primary repair of an atrial septal defect: Thrombus masquerading as a myxoma ANNALS OF THORACIC SURGERY Sheikh, A. Y., Schrepfer, S., Stein, W., West, J., Lombard, J., Burdon, T., Pinsker, B., Pelletier, M. P. 2007; 84 (5): 1742-1744


    Atrial septal defects are among the most common congenital anomalies requiring surgical repair. Thrombus formation after patch-based repair is a recognized complication, usually manifested by an embolic event. However, thromboembolic complications after primary repair of atrial septal defects are exceedingly rare. We present a 38-year-old woman found to have a right atrial mass diagnosed as a myxoma by echocardiography and magnetic resonance imaging 3 years after primary atrial septal defect repair. However, final pathology revealed an organized thrombus. A review of the literature and clinical management of postoperative atrial thrombi are discussed.

    View details for DOI 10.1016/j.athoracsur.2007.05.065

    View details for Web of Science ID 000250782500050

    View details for PubMedID 17954102

  • Differentiation, survival, and function of embryonic stem cell-derived endothelial cells for ischemic heart disease CIRCULATION Li, Z., Wu, J. C., Sheikh, A. Y., Kraft, D., Cao, F., Xie, X., Patel, M., Gambhir, S. S., Robbins, R. C., Cooke, J. P., Wu, J. C. 2007; 116 (11): I46-I54


    Embryonic stem (ES) cells are distinguished by their capacity for self-renewal and pluripotency. Here we characterize the differentiation of ES cell-derived endothelial cells (ESC-ECs), use molecular imaging techniques to examine their survival in vivo, and determine the therapeutic efficacy of ESC-ECs for restoration of cardiac function after ischemic injury.Murine ES cells were transfected with a construct composed of a vascular endothelial cadherin promoter driving enhanced green fluorescence protein (pVE-cadherin-eGFP). Differentiation of ES cells to ECs was detected by FACS analysis using Flk-1 (early EC marker at day 4) and VE-cadherin (late EC marker at day 8). After isolation, these ESC-ECs express endothelial cell markers similar to adult mouse lung endothelial cells, form vascular-like channels, and incorporate DiI-labeled acetylated low-density lipoprotein (DiI-Ac-LDL). For in vivo imaging, ES cells were transduced with an ubiquitin promoter driving firefly luciferase and monomeric red fluorescence protein (pUb-Fluc-mRFP). A robust correlation exists between Fluc signals and cell numbers by ex vivo imaging analysis (R2=0.98) and by in vitro enzyme assay (R2=0.94). Afterward, 5x10(5) ESC-ECs or PBS (as control) was injected into the hearts of mice undergoing LAD ligation (n=15 per group). Bioluminescence imaging showed longitudinal survival of transplanted ESC-ECs for approximately 8 weeks. Echocardiogram demonstrated significant functional improvement in the ESC-EC group compared with control (P=0.04). Finally, postmortem analysis confirmed increased presence of small capillaries and venules in the infarcted zones by CD31 staining.This is the first study to track the fate and function of transplanted ESC-ECs in the heart. With further validation, these ESC-ECs could become a valuable source of cell therapy for induction of angiogenesis in the treatment of myocardial ischemia.

    View details for DOI 10.1161/CIRCULATIONAHA.106.680561

    View details for Web of Science ID 000249364500007

    View details for PubMedID 17846325

  • Positron emission tomography imaging of conditional gene activation in the heart JOURNAL OF MOLECULAR AND CELLULAR CARDIOLOGY Chang, G. Y., Cao, F., Krishnan, M., Huang, M., Li, Z., Xie, X., Sheikh, A. Y., Hoyt, G., Robbins, R. C., Hsial, T., Schneider, M. D., Wu, J. C. 2007; 43 (1): 18-26


    The Cre-loxP system has been routinely used for conditional activation and deletion of gene expression. However, the spatiotemporal manner of these events in the heart has not yet been defined by in vivo imaging. Adenovirus (1 x 10(9 )pfu) carrying the silent positron emission tomography (PET) reporter gene, herpes simplex virus type 1 thymidine kinase (HSV1-tk), was injected into the left ventricular wall of male transgenic mice (n=15) or FVB controls (n=8). Transgenic mice expressed Cre recombinase driven by a cardiac-specific alpha-myosin heavy chain (alpha-MHC) promoter. Following injection of the 9-[4-fluoro-3-(hydroxymethyl)butyl]guanine ([18F]-FHBG; 137+/-25 microCi) reporter probe, microPET imaging was used to assess the expression of HSV1-tk reporter gene in the myocardium. Two days following adenoviral injection, cardiac HSV1-tk gene activation resulted in tracer uptake of 3.20+/-0.51% ID/g for alpha-MHC-Cre and 0.05+/-0.02%ID/g for control mice (P<0.01). The in vivo results were confirmed by RT-PCR and Western blot analysis. Similar transfections were evaluated in both cardiac-specific and non-cardiac-specific cell lines. Enzyme activity showed a robust correlation (r2=0.82) between in vivo molecular imaging technique and traditional in vitro enzyme assays. With further development and validation, PET imaging will likely play an important role in the noninvasive, repetitive, and quantitative measurement of conditional gene activation in the future.

    View details for DOI 10.1016/j.yjmcc.2007.03.809

    View details for Web of Science ID 000248001400004

    View details for PubMedID 17467733

  • Magnetic resonance imaging of progressive cardiomyopathic changes in the db/db mouse AMERICAN JOURNAL OF PHYSIOLOGY-HEART AND CIRCULATORY PHYSIOLOGY Yue, P., Arai, T., Terashima, M., Sheikh, A. Y., Cao, F., Charo, D., Hoyt, G., Robbins, R. C., Ashley, E. A., Wu, J., Yang, P. C., Tsao, P. S. 2007; 292 (5): H2106-H2118


    The db/db mouse is a well-established model of diabetes. Previous reports have documented contractile dysfunction (i.e., cardiomyopathy) in these animals, although the extant literature provides limited insights into cardiac structure and function as they change over time. To better elucidate the natural history of cardiomyopathy in db/db mice, we performed cardiac magnetic resonance (CMR) scans on these animals. CMR imaging was conducted with a 4.7-T magnet on female db/db mice and control db/+ littermates at 5, 9, 13, 17, and 22 wk of age. Gated gradient echo sequences were used to obtain cineographic short-axis slices from apex to base. From these images left ventricular (LV) mass (LVM), wall thickness, end-diastolic volume (LVEDV), and ejection fraction (LVEF) were determined. Additionally, cardiac [(18)F]fluorodeoxyglucose ([(18)F]FDG) PET scanning, pressure-volume loops, and real-time quantitative PCR on db/db myocardium were performed. Relative to control, db/db mice developed significant increases in LVM and wall thickness as early as 9 wk of age. LVEDV diverged slightly later, at 13 wk. Interestingly, compared with the baseline level, LVEF in the db/db group did not decrease significantly until 22 wk. Additionally, [(18)F]FDG metabolic imaging showed a 40% decrease in glucose uptake in db/db mice. Furthermore, contractile dysfunction was observed in 15-wk db/db mice undergoing pressure-volume loops. Finally, real-time quantitative PCR revealed an age-dependent recapitulation of the fetal gene program, consistent with a myopathic process. In summary, as assessed by CMR, db/db mice develop characteristic structural and functional changes consistent with cardiomyopathy.

    View details for DOI 10.1152/ajpheart.00856.2006

    View details for Web of Science ID 000247777200012

    View details for PubMedID 17122193

  • Comment on "Transplantation of undifferentiated murine embryonic stem cells in the heart: teratoma formation and immune response" FASEB JOURNAL Swijnenburg, R., Sheikh, A. Y., Robbins, R. C. 2007; 21 (7): 1290-1290

    View details for DOI 10.1096/fj.07-0502ufm

    View details for Web of Science ID 000246117000002

    View details for PubMedID 17470572

  • Molecular imaging of embryonic stem cell misbehavior and suicide gene ablation CLONING AND STEM CELLS Cao, F., Drukker, M., Lin, S., Sheikh, A. Y., Xie, X., Li, Z., Connolly, A. J., Weissman, I. L., Wu, J. C. 2007; 9 (1): 107-117


    Numerous studies have demonstrated the potential use of stem cells for the repair and regeneration of injured tissues. However, tracking transplanted stem cell fate and function in vivo remains problematic. To address these issues, murine embryonic stem (ES) cells were stably transduced with self-inactivating lentiviral vectors carrying either a triple fusion (TF) or double fusion (DF) reporter gene construct. The TF consisted of monomeric red fluorescence protein (mrfp), firefly luciferase (Fluc), and herpes simplex virus truncated thymidine kinase (HSV-ttk) reporter genes. The DF consisted of enhanced green fluorescence protein (egfp) and Fluc reporter genes but lacked HSV-ttk. Stably transduced ES-TF or ES-DF cells were selected by fluorescence activated cell sorting based on either mrfp (TF) or egfp (DF) expression. Afterwards, cells were injected subcutaneously into the right (ES-TF cells) and left (ES-DF cells) shoulders of adult female nude mice. Cell survival was tracked noninvasively by bioluminescence and positron emission tomography imaging of Fluc and HSV-ttk reporter genes, respectively. Imaging signals progressively increased from day 2 to day 14, consistent with ES cell survival and proliferation in vivo. However, teratoma formation occurred in all nude mice after 5 weeks. Administration of ganciclovir (GCV), targeting the HSV-ttk gene, resulted in selective ablation of teratomas arising from the ES-TF cells but not ES-DF cells. These data demonstrate the novel use of multimodality imaging techniques to (1) monitor transplanted ES cell survival and proliferation in vivo and (2) assess the efficacy of suicide gene therapy as a backup safety measure against teratoma formation.

    View details for DOI 10.1089/clo.2006.0016

    View details for Web of Science ID 000245390300015

    View details for PubMedID 17386018

  • Pulmonary arterial hypertension is linked to insulin resistance and reversed by peroxisome proliferator-activated receptor-gamma activation CIRCULATION Hansmann, G., Wagner, R. A., Schellong, S., Perez, V. A., Urashima, T., Wang, L., Sheikh, A. Y., Suen, R. S., Stewart, D. J., Rabinovitch, M. 2007; 115 (10): 1275-1284


    Patients with pulmonary arterial hypertension (PAH) have reduced expression of apolipoprotein E (apoE) and peroxisome proliferator-activated receptor-gamma in lung tissues, and deficiency of both has been linked to insulin resistance. ApoE deficiency leads to enhanced platelet-derived growth factor signaling, which is important in the pathobiology of PAH. We therefore hypothesized that insulin-resistant apoE-deficient (apoE-/-) mice would develop PAH that could be reversed by a peroxisome proliferator-activated receptor-gamma agonist (eg, rosiglitazone).We report that apoE-/- mice on a high-fat diet develop PAH as judged by elevated right ventricular systolic pressure. Compared with females, male apoE-/- were insulin resistant, had lower plasma adiponectin, and had higher right ventricular systolic pressure associated with right ventricular hypertrophy and increased peripheral pulmonary artery muscularization. Because male apoE-/- mice were insulin resistant and had more severe PAH than female apoE-/- mice, we treated them with rosiglitazone for 4 and 10 weeks. This treatment resulted in markedly higher plasma adiponectin, improved insulin sensitivity, and complete regression of PAH, right ventricular hypertrophy, and abnormal pulmonary artery muscularization in male apoE-/- mice. We further show that recombinant apoE and adiponectin suppress platelet-derived growth factor-BB-mediated proliferation of pulmonary artery smooth muscle cells harvested from apoE-/- or C57Bl/6 control mice.We have shown that insulin resistance, low plasma adiponectin levels, and deficiency of apoE may be risk factors for PAH and that peroxisome proliferator-activated receptor-gamma activation can reverse PAH in an animal model.

    View details for DOI 10.1161/CIRCULATIONAHA.106.663120

    View details for Web of Science ID 000244864100017

    View details for PubMedID 17339547

  • In vivo optical bioluminescence imaging of collagen-supported cardiac cell grafts JOURNAL OF HEART AND LUNG TRANSPLANTATION Kutschka, I., Chen, I. Y., Kofidis, T., von Degenfeld, G., Sheikh, A. Y., Hendry, S. L., Hoyt, G., Pearl, J., Blau, H. M., Gambhir, S. S., Robbins, R. C. 2007; 26 (3): 273-280


    Histology-based survival assessment of cell grafts does not allow for in vivo follow-up. In this study we introduce two new experimental models for longitudinal in vivo survival studies of cardiac cell grafts using optical bioluminescence imaging.H9c2 cardiomyoblasts expressing both firefly luciferase (fluc) and green fluorescent protein (GFP) reporter genes were implanted into Lewis rats. In Model 1, H9c2-fluc-IRES-GFP cells (0.5 x 10(6)) were implanted into a cryoinjured abdominal wall muscle. Cells were injected using either liquid collagen (Matrigel [MG]) or phosphate-buffered saline (PBS) suspension. Cell survival was evaluated in vivo using bioluminescence imaging on days 1, 5 and 10 post-operatively. In model 2, rats underwent ligation of the left anterior descending (LAD) artery. The donor hearts were harvested, and the infarcted region was restored ex situ using 1 x 10(6) H9c2-fluc-IRES-GFP cells seeded in collagen matrix (Gelfoam [GF]) or suspended in PBS (n = 8/group). Hearts were then transplanted into the abdomen of syngeneic recipients. Optical bioluminescence imaging was performed on Days 1, 5, 8 and 14 post-operatively. After 4 weeks, immunohistologic studies were performed.For model 1, at day 5, bioluminescence signals were markedly higher for the H9c2/MG group (449 +/- 129 photons/second x 10(3)) compared with the H9c2/PBS group (137 +/- 82 photons/second x 10(3)) (p < 0.05). For model 2, bioluminescence signals were significantly (p < 0.04) higher in the H9c2/GF group compared with plain cell injection on days 5 (534 +/- 115 vs 219 +/- 34) and 8 (274 +/- 34 vs 180 +/- 23). Data were in accordance with GFP immunohistology.Optical bioluminescence is a powerful method for assessment of cardiac cell graft survival in vivo. Collagen matrices support early survival of cardiomyoblasts after transplantation into injured musculature.

    View details for Web of Science ID 000244979000010

    View details for PubMedID 17346630

  • Clinical hurdles for the transplantation of cardiomyocytes derived from human embryonic stem cells: role of molecular imaging CURRENT OPINION IN BIOTECHNOLOGY Swijnenburg, R., van der Bogt, K. E., Sheikh, A. Y., Cao, F., Wu, J. C. 2007; 18 (1): 38-45


    Over the past few years, human embryonic stem cells (hESCs) have gained popularity as a potentially ideal cell candidate for tissue regeneration. In particular, hESCs are capable of cardiac lineage-specific differentiation and confer improvement of cardiac function following transplantation into animal models. Although such data are encouraging, there remain significant hurdles before safe and successful translation of hESC-based treatment into clinical therapy, including the ability to assess cells following transplant. To this end, molecular imaging has proven a reliable methodology for tracking the long-term fate of transplanted cells. Imaging reporter genes that are introduced into the cells before transplantation enable non-invasive and longitudinal studies of cell viability, location and behaviour in vivo. Therefore, molecular imaging is expected to play an increasing role in characterizing the biology and physiology of hESC-derived cardiac cells in living subjects.

    View details for DOI 10.1016/j.copbio.2006.12.003

    View details for Web of Science ID 000244593000007

    View details for PubMedID 17196814

  • Molecular Imaging of bone marrow mononuclear cell homing and engraftment in ischemic myocardium STEM CELLS Sheikh, A. Y., Lin, S., Cao, F., Cao, Y., van der Bogt, K. E., Chu, P., Chang, C., Contag, C. H., Robbins, R. C., Wu, J. C. 2007; 25 (10): 2677-2684


    Bone marrow mononuclear cell (BMMC) therapy shows promise as a treatment for ischemic heart disease. However, the ability to monitor long-term cell fate remains limited. We hypothesized that molecular imaging could be used to track stem cell homing and survival after myocardial ischemia-reperfusion (I/R) injury. We first harvested donor BMMCs from adult male L2G85 transgenic mice constitutively expressing both firefly luciferase (Fluc) and enhanced green fluorescence protein reporter gene. Fluorescence-activated cell sorting analysis revealed approximately 0.07% of the population to consist of classic hematopoietic stem cells (lin-, thy-int, c-kit+, Sca-1+). Afterward, adult female FVB recipients (n = 38) were randomized to sham surgery or acute I/R injury. Animals in the sham (n = 16) and I/R (n = 22) groups received 5 x 10(6) of the L2G85-derived BMMCs via tail vein injection. Bioluminescence imaging (BLI) was used to track cell migration and survival in vivo for 4 weeks. BLI showed preferential homing of BMMCs to hearts with I/R injury compared with sham hearts within the first week following cell injection. Ex vivo analysis of explanted hearts by histology confirmed BLI imaging results, and quantitative real-time polymerase chain reaction (for the male Sry gene) further demonstrated a greater number of BMMCs in hearts with I/R injury compared with the sham group. Functional evaluation by echocardiography demonstrated a trend toward improved left ventricular fractional shortening in animals receiving BMMCs. Taken together, these data demonstrate that molecular imaging can be used to successfully track BMMC therapy in murine models of heart disease. Specifically, we have demonstrated that systemically delivered BMMCs preferentially home to and are retained by injured myocardium. Disclosure of potential conflicts of interest is found at the end of this article.

    View details for DOI 10.1634/stemcells.2007-0041

    View details for Web of Science ID 000249929900031

    View details for PubMedID 17628019

  • Experimental orthotopic tracheal transplantation: The Stanford technique MICROSURGERY Schrepfer, S., Deuse, T., Hoyt, G., Sheikh, A., Hoffmann, J., Reichenspurner, H., Robbins, R. C., Pelletier, M. P. 2007; 27 (3): 187-189


    The rat heterotopic tracheal transplantation model is widely used as an experimental model to study the development of obliterative airway disease (OAD) and to assess immunosuppressive strategies for chronic rejection. Despite its widespread application, the heterotopic transplantation model does have a number of limitations like the lack of air flow and mucociliary clearance. The present article provides a detailed description of the surgical technique for orthotopic tracheal transplantations, which may share more similarities with lung transplants in humans. The technique is easy to learn, the procedure is well tolerated by the animals, and the grafts develop OAD lesions similar to those of human obliterative bronchiolitis.

    View details for DOI 10.1002/micr.20329

    View details for Web of Science ID 000245596100006

    View details for PubMedID 17326196

  • Genetic modification of embryonic stem cells with VEGF enhances cell survival and improves cardiac function CLONING AND STEM CELLS Xie, X., Cao, F., Sheikh, A. Y., Li, Z., Connolly, A. J., Pei, X., Li, R., Robbins, R. C., Wui, J. C. 2007; 9 (4): 549-563


    Cardiac stem cell therapy remains hampered by acute donor cell death posttransplantation and the lack of reliable methods for tracking cell survival in vivo. We hypothesize that cells transfected with inducible vascular endothelial growth factor 165 (VEGF(165)) can improve their survival as monitored by novel molecular imaging techniques. Mouse embryonic stem (ES) cells were transfected with an inducible, bidirectional tetracycline (Bi-Tet) promoter driving VEGF(165) and renilla luciferase (Rluc). Addition of doxycycline induced Bi-Tet expression of VEGF(165) and Rluc significantly compared to baseline (p<0.05). Expression of VEGF(165) enhanced ES cell proliferation and inhibited apoptosis as determined by Annexin-V staining. For noninvasive imaging, ES cells were transduced with a double fusion (DF) reporter gene consisting of firefly luciferase and enhanced green fluorescence protein (Fluc-eGFP). There was a robust correlation between cell number and Fluc activity (R(2)=0.99). Analysis by immunostaining, histology, and RT-PCR confirmed that expression of Bi-Tet and DF systems did not affect ES cell self-renewal or pluripotency. ES cells were differentiated into beating embryoid bodies expressing cardiac markers such as troponin, Nkx2.5, and beta-MHC. Afterward, 5 x 10(5) cells obtained from these beating embryoid bodies or saline were injected into the myocardium of SV129 mice (n=36) following ligation of the left anterior descending (LAD) artery. Bioluminescence imaging (BLI) and echocardiography showed that VEGF(165) induction led to significant improvements in both transplanted cell survival and cardiac function (p<0.05). This is the first study to demonstrate imaging of embryonic stem cell-mediated gene therapy targeting cardiovascular disease. With further validation, this platform may have broad applications for current basic research and further clinical studies.

    View details for DOI 10.1089/clo.2007.0032

    View details for Web of Science ID 000252027800010

    View details for PubMedID 18154515

  • Collagen matrices enhance survival of transplanted cardiomyoblasts and contribute to functional improvement of ischemic rat hearts CIRCULATION Kutschka, I., Chen, I. Y., Kofidis, T., Arai, T., von Degenfeld, G., Sheikh, A. Y., Hendry, S. L., Pearl, J., Hoyt, G., Sista, R., Yang, P. C., Blau, H. M., Gambhir, S. S., Robbins, R. C. 2006; 114: I167-I173


    Cardiac cell transplantation is limited by poor graft viability. We aimed to enhance the survival of transplanted cardiomyoblasts using growth factor-supplemented collagen matrices.H9c2 cardiomyoblasts were lentivirally transduced to express firefly luciferase and green fluorescent protein (GFP). Lewis rats underwent ligation of the left anterior descending artery (LAD) ligation to induce an anterior wall myocardial infarction. Hearts (n=9/group) were harvested and restored ex vivo with 1 x 10(6) genetically labeled H9c2 cells either in (1) saline-suspension, or seeded onto (2) collagen-matrix (Gelfoam [GF];), (3) GF/Matrigel (GF/MG), (4) GF/MG/VEGF (10 microg/mL), or (5) GF/MG/FGF (10 microg/mL). Hearts were then abdominally transplanted into syngeneic recipients (working heart model). Controls (n=6/group) underwent infarction followed by GF implantation or saline injection. Cell survival was evaluated using optical bioluminescence on days 1, 5, 8, 14, and 28 postoperatively. At 4 weeks, fractional shortening and ejection fraction were determined using echocardiography and magnetic resonance imaging, respectively. Graft characteristics were assessed by immunohistology. Bioluminescence signals on days 5, 8, and 14 were higher for GF-based grafts compared with plain H9c2 injections (P<0.03). Signals were higher for GF/MG grafts compared with GF alone (P<0.02). GFP-positive, spindle-shaped H9c2 cells were found integrated in the infarct border zones at day 28. Left ventricular (LV) function of hearts implanted with collagen-based grafts was better compared with controls (P<0.05). Vascular endothelial growth factor or fibroblast growth factor did not further improve graft survival or heart function.Collagen matrices enhance early survival of H9c2 cardiomyoblasts after transplantation into ischemic hearts and lead to improved LV function. Further optimization of the graft design should make restoration of large myocardial infarctions by tissue engineering approaches effective.

    View details for DOI 10.1161/CIRCULATIONAHA.105.001297

    View details for Web of Science ID 000238688200028

    View details for PubMedID 16820568

  • Adenoviral human BCL-2 transgene expression attenuates early donor cell death after cardiomyoblast transplantation into ischemic rat hearts CIRCULATION Kutschka, I., Kofidis, T., Chen, I. Y., von Degenfeld, G., Zwierzchoniewska, M., Hoyt, G., Arai, T., Lebl, D. R., Hendry, S. L., Sheikh, A. Y., Cooke, D. T., Connolly, A., Blau, H. M., Gambhir, S. S., Robbins, R. C. 2006; 114: I174-I180


    Cell transplantation for myocardial repair is limited by early cell death. Gene therapy with human Bcl-2 (hBcl-2) has been shown to attenuate apoptosis in the experimental setting. Therefore, we studied the potential benefit of hBcl-2 transgene expression on the survival of cardiomyoblast grafts in ischemic rat hearts.H9c2 rat cardiomyoblasts were genetically modified to express both firefly luciferase and green fluorescent protein (mH9c2). The cells were then transduced with adenovirus carrying hBcl-2 (AdCMVhBcl-2/mH9c2). Lewis rats underwent ligation of the left anterior descending artery (LAD) to induce a sizable left ventricular (LV) infarct. Hearts were explanted and the infarcted region was restored using collagen matrix (CM) seeded with 1x10(6) mH9c2 cells (n=9) or AdCMVhBcl-2/mH9c2 cells (n=9). Control animals received CM alone (n=6) or no infarct (n=6). Restored hearts were transplanted into the abdomen of syngeneic recipients in a "working heart" model. Cell survival was evaluated using optical bioluminescence imaging on days 1, 5, 8, 14, and 28 after surgery. The left heart function was assessed 4 weeks postoperatively using echocardiography and magnetic resonance imaging. During 4 weeks after surgery, the optical imaging signal for the AdCMVhBCL2/mH9c2 group was significantly (P<0.05) higher than that of the mH9c2-control group. Both grafts led to better fractional shortening (AdCMVhBcl-2/mH9c2: 0.21+/-0.03; mH9c2: 0.21+/-0.04; control: 0.15+/-0.03; P=0.04) and ejection fraction (AdCMVhBcl-2/mH9c2: 47.0+/-6.2; mH9c2: 48.7+/-6.1; control: 34.3+/-6.0; P=0.02) compared with controls. Importantly, no malignant cells were found in postmortem histology.Transduction of mH9c2 cardiomyoblasts with AdCMVhBcl-2 increased graft survival in ischemic rat myocardium without causing malignancies. Both AdCMVhBcl-2/mH9c2 and mH9c2 grafts improved LV function.

    View details for DOI 10.1161/CIRCULATIONAHA.105.001370

    View details for Web of Science ID 000238688200029

    View details for PubMedID 16820569

  • Transcriptional profiling of reporter genes used for molecular imaging of embryonic stem cell transplantation PHYSIOLOGICAL GENOMICS Wu, J. C., Spin, J. M., Cao, F., Lin, S. A., Xie, X. Y., Gheysens, O., Chen, I. Y., Sheikh, A. Y., Robbins, R. C., Tsalenko, A., Gambhir, S. S., Quertermous, T. 2006; 25 (1): 29-38


    Stem cell therapy offers exciting promise for treatment of ischemic heart disease. Recent advances in molecular imaging techniques now allow investigators to monitor cell fate noninvasively and repetitively. Here we examine the effects of a triple-fusion reporter gene on embryonic stem (ES) cell transcriptional profiles. Murine ES cells were stably transfected with a self-inactivating lentiviral vector carrying a triple-fusion (TF) construct consisting of fluorescence, bioluminescence, and positron emission tomography (PET) reporter genes. Fluorescence-activated cell sorting (FACS) analysis allowed isolation of stably transfected populations. Microarray studies comparing gene expression in nontransduced control ES cells vs. stably transduced ES cells expressing triple fusion (ES-TF) revealed some increases in transcriptional variability. Annotation analysis showed that ES-TF cells downregulated cell cycling, cell death, and protein and nucleic acid metabolism genes while upregulating homeostatic and anti-apoptosis genes. Despite these transcriptional changes, expression of the TF reporter gene had no significant effects on ES cell viability, proliferation, and differentiation capability. Importantly, transplantation studies in murine myocardium demonstrated the feasibility of tracking ES-TF cells in living subjects using bioluminescence and PET imaging. Taken together, this is the first study to analyze in detail the effects of reporter genes on molecular imaging of ES cells.

    View details for DOI 10.1152/physiolgenomics.00254.2005

    View details for Web of Science ID 000236722700004

    View details for PubMedID 16390873

  • Molecular imaging of cardiac stem cell transplantation. Current cardiology reports Sheikh, A. Y., Wu, J. C. 2006; 8 (2): 147-154


    In recent years, stem cell therapy for the treatment of heart disease has translated from the imagination of investigators to the bedside of patients. The initial results from trials evaluating cell therapy for the heart are encouraging. As this new field of cellular transplantation matures, it is imperative that novel methodologies for evaluating cell therapy are developed and applied to guide therapy. Molecular imaging is a discipline that is evolving to address these needs and is expected to play an increasing role in the characterization and assessment of cell therapy. This article provides a focused overview of clinical stem cell therapy for the heart, followed by a discussion of how novel molecular imaging techniques are presently being applied to monitor cell therapy.

    View details for PubMedID 16524542

  • Hyperoxia improves microvascular perfusion in a murine wound model WOUND REPAIR AND REGENERATION Sheikh, A. Y., Rollins, M. D., Hopf, H. W., Hunt, T. K. 2005; 13 (3): 303-308


    There is a need for a noninvasive method that measures wound angiogenesis. Hyperoxia is known to increase the appearance of new blood vessels in wounds, yet no study has confirmed increases in wound bed perfusion with periodic hyperbaric oxygen (HBO) exposure. This study investigates whether laser Doppler imaging is able to detect and quantify the enhancement of wound angiogenesis that is known to occur with intermittent HBO treatments. Full-thickness dorsal dermal wounds were created on mice randomized to hyperoxic (n = 14) and control (n = 15) groups. Hyperbaric oxygen was administered twice daily for 90 minutes each at 2.1 atmospheres for 7 days. Wound bed perfusion was measured by laser Doppler imaging on days 0, 7, and 10 postwounding. Wound blood flow increased significantly over baseline on day 7 and 10 in the hyperoxic group, but only on day 10 in the control group. Comparison between groups showed a 20% statistically significant increase in wound perfusion in HBO-treated animals compared to control on day 10 (p = 0.05). Laser Doppler imaging was able to detect and quantify the increase in wound bed perfusion resulting from intermittent HBO treatments and shows promise as a noninvasive measure of angiogenesis and wound healing.

    View details for Web of Science ID 000229491600013

    View details for PubMedID 15953050

  • Effect of hyperoxia on vascular endothelial growth factor levels in a wound model ARCHIVES OF SURGERY Sheikh, A. Y., Gibson, J. J., Rollins, M. D., Hopf, H. W., Hussain, Z., Hunt, T. K. 2000; 135 (11): 1293-1297


    Hyperbaric oxygen (HBO) therapy increases vascular endothelial growth factor (VEGF) levels in wounds.Wounds were monitored for oxygen delivery during HBO treatment, and wound fluids were analyzed for VEGF and lactate on days 2, 5, and 10 following wounding.Experimental animal model.Rats were randomized to HBO therapy and control groups. The HBO therapy was administered for 90 minutes, twice daily with 100% oxygen at 2.1 atmospheres absolute. Treatment was administered for 7 days following wounding.Vascular endothelial growth factor, PO(2), and lactate levels in wound fluid were measured on days 2, 5, and 10.Wound oxygen rises with HBO from nearly 0 mm Hg to as high as 600 mm Hg. The peak level occurs at the end of the 90-minute treatment, and hyperoxia of lessening degree persists for approximately 1 hour. The VEGF levels significantly increase with HBO by approximately 40% 5 days following wounding and decrease to control levels 3 days after exposures are stopped. Wound lactate levels remain unchanged with HBO treatment (range, 2.0-10.5 mmol/L).Increased VEGF production seems to explain in part the angiogenic action of HBO. This supports other data that hypoxia is not necessarily a requirement for wound VEGF production.

    View details for Web of Science ID 000165055400008

    View details for PubMedID 11074883

Conference Proceedings

  • Surgical outcomes for patients with pulmonary atresia/major aortopulmonary collaterals and Alagille syndrome Mainwaring, R. D., Sheikh, A. Y., Punn, R., Reddy, V. M., Hanley, F. L. OXFORD UNIV PRESS INC. 2012: 235-241


    Pulmonary atresia with major aortopulmonary collateral arteries (PA/MAPCAs) is a complex congenital heart defect that has undergone significant advances in treatment over the past 15 years. A small subset of patients with PA/MAPCAs have associated Alagille syndrome, which can have an adverse impact on many other organ systems. The purpose of this study was to review our institutional outcomes for the surgical patients with PA/MAPCAs and Alagille syndrome.This was a retrospective review of patients with PA/MAPCA's and Alagille who underwent surgical reconstruction from November 2001 to August 2011. Fifteen patients were identified in our data base. Thirteen had pulmonary atresia with ventricular septal defect (PA/VSD) and two had pulmonary atresia with intact ventricular septum (PA-IVS).There has been no early or late mortality in this cohort of 15 patients with PA/MAPCA' and Alagille syndrome. The patients have undergone a total of 38 cardiac surgical procedures. Ten of the 13 patients with PA/VSD have achieved complete repair, including unifocalization, a right ventricle to pulmonary artery conduit and closure of all intra-cardiac shunts. The three unrepaired patients with PA/VSD remain potential candidates for eventual complete repair, while the two patients with PA-IVS remain viable candidates for a single ventricle pathway. The patients in this series have also undergone 12 major non-cardiac procedures.The data demonstrate that surgical reconstruction of PA/MAPCAs can be successfully achieved in patients with Alagille syndrome. The longer-term prognosis remains guarded on the basis of the multi-organ system involvement of Alagille syndrome.

    View details for DOI 10.1093/ejcts/ezr310

    View details for Web of Science ID 000306365600013

    View details for PubMedID 22402453

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