Objective: To investigate the effect of transfection of 5-aza cytidine (5-aza) induced BMSCs that were transfected with Ad. ANG ex vivo into infarcted myocardium.
Methods: Lewis rat BMSCs were cultured in vitro and incubated together with 5-aza (3 micro mol/l) for 24 hours, and the induced BMSCs were transfected with Ad. ANG with a infection multiple of 50. ELISA method was applied to assay the expression and secretion of ANG in the medium. Then such BMSCs expressing ANG were transplanted into the ischemic myocardium of 14 Lewis rats whose left descending branch of coronary artery had been ligated 4 weeks ago (Group I). Eight rats with infarcted myocardium were transplanted with such BMSCs too (group II). Another eight rats received only Ad. ANG injection (group III). Twelve rats receiving serum-free medium injection were used as controls (Group IV). Four weeks after the ligation of LDA (for group I) and 4 weeks after the beginning of experiment (for all groups), the parameters of heart function, such as ejection fraction (EF) and end-diastole volume of left heart (EDLV), were examined by echocardiography. Four weeks after the beginning of experiment, the rats were killed, and the survival and differentiation of transplanted BMSCs and angiogenesis were observed by immunohistochemistry and transmission electron micrography.
Results: One day after the beginning of experiment, the concentration of ANG in the supernatant of medium was 162 +/- 10 pg/ml, significantly higher than that in the supernatant of medium in control group (86 +/- 5 pg/ml, P < 0.01). The concentration of ANG gradually increased and reached its peak at the 4th to 7th day; ANG could still be assayed 15 days later. 4 weeks after the transplantation, most of the 5-aza-induced BMSCs in group I and group II had differentiated into cardiomyogenic cells in the transplanted area. The EF value was 0.42 +/- 0.114 weeks after ligation of LAD, and was 0.69 +/- 0.034 weeks after the transplantation in group I. The EF value was 0.46 +/- 0.06 at the beginning of experiment and was 0.64 +/- 0.144 weeks after the transplantation in group II. The improvement of EF in Group I was significantly than that in other 3 groups (P < 0.05 or P < 0.01). The number of new vessels in group I was 36.3/high-power field (HPF), significantly higher than those in the other three groups (10.5/HPF in Group II, 23.1/HPF in Group III, and 0.9/HPF in Group IV).
Conclusion: Induced by 5-aza, BMSCs differentiate into cardiomyogenic cells in infracted myocardium. ANG-expressing BMSCs transplantation is one of the safe and beneficial new strategies for repairing damaged myocardium and enhancing angiogenesis in ischemic myocardium.