Introduction: GATA4 is an early cardiac-specific transcription factor, and endogenous GATA4 positive (GATA4pos) cells play a critical role for naturally-occurring cardiac repair after myocardial injury. Given the limited number of GATA4pos cardiac progenitor cells (CPC) in adult heart, replenish GATA4pos CPC might improve heart regeneration after myocardial injury.
Hypothesis: We want to test the feasibility of isolating GATA4pos CPC via GATA4 promoter activity, and determine whether replenishing the pool of GATA4pos CPC in ischemic heart can potentiating the naturally occurring process for heart repair.
Methods: A lentiviral vector in which the expression of eGFP reporter is driven by a 1kb fragment of the mouse GATA4 promoter was constructed. Murine CPC with high GFP intensity were sorted by FACS, and characterized.
Results: Western blot shows that the CPC population with high GFP intensity exhibits higher GATA4 protein expression as compared with unsorted CPC. Interestingly, we observed that sorted GATA4pos CPC also exhibit higher HIF-1α protein expression as compared with unsorted CPC. We compared hypoxia- and serum deprivation induced-apoptosis between sorted GATA4pos CPC and unsorted CPC by TUNEL staining. We found that the GATA4pos CPC exhibited lower rate of TUNEL positivity as compared with unsorted CPC, suggesting GATA4pos CPC are more resistant to hypoxia- and serum deprivation-induced apoptosis in comparison with unsorted CPC. In mouse model of myocardial infarction by permanent left coronary ligation, GATA4pos CPC or unsorted CPC was injected into the peri-infarct zone of heart. Left ventricular ejection fraction (EF) were serially (days 1 and 14) assessed using echocardiography. At day 1, no differences in EF were observed between GATA4pos CPC and unsorted CPC group (n=9, ns). At day 14, left ventricular ejection fraction in GATA4pos CPC cell-treated group was improved about 11.2% compared with the unsorted CPC group (n=9, P<0.05).
Conclusions: GATA4pos CPC, as compared with unsorted CPC, exhibit enhanced effect on potentiating the naturally occurring process for repair of damaged heart, therefore, GATA4pos CPC can be considered as a much more potential progenitor for heart repair.