“Triplet” polycistronic vectors encoding Gata4, Mef2c, and Tbx5 enhances postinfarct ventricular functional improvement compared with singlet vectors

• Published in: The Journal of thoracic and cardiovascular surgery Vol. 148; no. 4; pp. 1656 - 1664.e2
• Main Authors: Mathison, Megumi, MD, PhD, Singh, Vivek P., PhD, Gersch, Robert P., PhD, Ramirez, Maricela O., BS, Cooney, Austin, PhD, Kaminsky, Stephen M., PhD, Chiuchiolo, Maria J., PhD, Nasser, Ahmed, MD, Yang, Jianchang, MD, PhD, Crystal, Ronald G., MD, Rosengart, Todd K., MD
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.10.2014
• Subjects: Adenoviridae - genetics; Animals; Blotting, Western; Cardiothoracic Surgery; Cell Differentiation - genetics; Cell Differentiation - physiology; Fibroblasts - pathology; GATA4 Transcription Factor - genetics; GATA4 Transcription Factor - physiology; Gene Transfer Techniques; Genetic Vectors; Male; MEF2 Transcription Factors - genetics; MEF2 Transcription Factors - physiology; Models, Animal; Myocardial Infarction - pathology; Myocytes, Cardiac - pathology; Myocytes, Cardiac - physiology; Myogenic Regulatory Factors - genetics; Myogenic Regulatory Factors - physiology; Rats; Rats, Inbred F344; T-Box Domain Proteins - genetics; T-Box Domain Proteins - physiology; Vascular Endothelial Growth Factor A - genetics; TU; cardiac troponin T; Ad; ejection fraction; G; FACS; phosphate-buffered saline; M; IMDM; GFP; adenoviral vector that does not encode a transgene; cytomegalovirus; T; FBS; adenovirus; cTnT; transducing units; Iscove's modified Dulbecco's medium; fluorescence activated cell sorting; PBS; EF; VEGF; Tbx5; CMV; green fluorescent protein; fetal bovine serum; 39.3; Mef2c; vascular endothelial growth factor; AdNull; Gata4
• ISSN: 0022-5223; 1097-685X
• DOI: 10.1016/j.jtcvs.2014.03.033

Objective The in situ reprogramming of cardiac fibroblasts into induced cardiomyocytes by the administration of gene transfer vectors encoding Gata4 (G), Mef2c (M), and Tbx5 (T) has been shown to improve ventricular function in myocardial infarction models. The efficacy of this strategy could, however, be limited by the need for fibroblast targets to be infected 3 times—once by each of the 3 transgene vectors. We hypothesized that a polycistronic “triplet” vector encoding all 3 transgenes would enhance postinfarct ventricular function compared with use of “singlet” vectors. Methods After validation of the polycistronic vector expression in vitro, adult male Fischer 344 rats (n = 6) underwent coronary ligation with or without intramyocardial administration of an adenovirus encoding all 3 major vascular endothelial growth factor (VEGF) isoforms (AdVEGF-All6A positive), followed 3 weeks later by the administration to AdVEGF-All6A-positive treated rats of singlet lentivirus encoding G, M, or T (1 × 105 transducing units each) or the same total dose of a GMT “triplet” lentivirus vector. Results Western blots demonstrated that triplet and singlet vectors yielded equivalent GMT transgene expression, and fluorescence activated cell sorting demonstrated that triplet vectors were nearly twice as potent as singlet vectors in generating induced cardiomyocytes from cardiac fibroblasts. Echocardiography demonstrated that GMT triplet vectors were more effective than the 3 combined singlet vectors in enhancing ventricular function from postinfarct baselines (triplet, 37% ± 10%; singlet, 13% ± 7%; negative control, 9% ± 5%; P  < .05). Conclusions These data have confirmed that the in situ administration of G, M, and T induces postinfarct ventricular functional improvement and that GMT polycistronic vectors enhance the efficacy of this strategy.