Fetal cell transplantation: A comparison of three cell types

Objective: We have previously reported that fetal cardiomyocyte transplanta tion into myocardial scar improves heart function. The mechanism by which t his occurs, however, has not been elucidated. To investigate possible mecha nisms by which cell transplantation may improve heart function, we compared cardiac function after transplantation of 3 different fetal cell types: ca rdiomyocytes, smooth muscle cells (nonstriated muscle cells), and fibroblas ts (noncontractile cells). Methods: A left ventricular scar was created by cryoinjury in adult rats. Four weeks after injury, cultured fetal ventricul ar cardiomyocytes (n = 13), enteric smooth muscle cells (n = 10), skin fibr oblasts (n = 10), or culture medium (control, n = 15 total) were injected i nto the myocardial scar. All rats received cyclosporine A (INN: ciclosporin ), Four weeks after transplantation, left ventricular function was evaluate d in a Langendorff preparation. Results: The implanted cells were identifie d histologically, All transplanted cell types formed tissue within the myoc ardial scar. At an end-diastolic volume of 0.2 mt, developed pressures in c ardiomyocytes group were significantly greater than smooth muscle cells and skin fibroblasts groups (cardiomyocytes, 134% +/- 22% of control; smooth m uscle cells, 108% +/- 14% of control; skin fibroblasts, 106% +/- 17% of con trol; P = .0001), as were +dP/dt(max) (cardiomyocytes, 119% +/- 37% of cont rol; smooth muscle cells, 98% +/- 18% of control; skin fibroblasts, 92% +/- 11% of control; P = .0001) and -dP/dt(max) (cardiomyocytes, 126% +/- 29% o f control; smooth muscle cells, 108% +/- 19% of control; skin fibroblasts, 99% +/- 16% control; P = .0001), Conclusions: Fetal cardiomyocytes transpla nted into myocardial scar provided greater contractility and relaxation tha n fetal smooth muscle cells or fetal fibroblasts, The contractile and elast ic properties of transplanted cells determine the degree of improvement in ventricular function achievable with cell transplantation.