CARDIOMYOCYTE TRANSPLANTATION IMPROVES HEART FUNCTION

Background. Transplantation of cultured cardiomyocytes into myocardial scar tissue may prevent heart failure. Methods. Scar tissue was produ ced in the left ventricular free wall of 15 rats (weight, 450 g) by cr yoinjury. Seven animals had operation only and survived for 8 weeks (s ham group). Four weeks after cryoinjury, cultured fetal rat cardiomyoc ytes or culture medium was injected into the scar tissue of transplant ation (n = 5) and control (n = 5) animals, respectively. Five other ra ts were sacrificed for scar assessment. Eight weeks after cryoinjury h eart function in the transplantation, control, and sham groups was mea sured using a Langendorff preparation. Histologic studies were perform ed to quantify the extent of the scar and the transplanted cells. Resu lts. Four weeks after cryoinjury, 36% +/- 4% (mean +/- 1 standard erro r) of the left ventricular free wall surface area was scar tissue. At 8 weeks, the scar size had increased (p < 0.01) to 55% +/- 3% in the c ontrol group. Although the scar size (43% +/- 2%) in the transplantati on group at 8 weeks was not significantly different from that at 4 wee ks, it was less (p < 0.05) than that in the control group. Hearts in t he sham group had no scar tissue. The transplanted cardiomyocytes had formed cardiac tissue within the myocardial scar. Systolic and develop ed pressures in the transplantation group hearts were greater (p = 0.0 001) than in the control group hearts but less (p < 0.01) than those i n the sham group hearts. Conclusions. The transplanted cardiomyocytes formed cardiac tissue in the myocardial scar, limited scar expansion, and improved heart function compared with findings in the control hear ts.