CALL GRAFTED CARDIOMYOCYTES COLONIZE PERIINFARCT MYOCARDIAL AREAS

Background Cell transplantation is emerging as a potential means of im proving repair of damaged organs. This preliminary study tests the fea sibility of grafting allogenic cells into the border zone of a myocard ial infarct (MI). Methods and Results Neonatal cardiomyocytes were obt ained from fetuses of female mts 20 days pregnant. They were then inje cted at three different sites (2 X 10(-6) cells per site) into the lef t ventricular (LV) myocardium of control rats (n=10) or of rats in whi ch MI had been created by proximal occlusion of the left coronary arte ry (n=10). In the latter case, injections were placed along the peri-i nfarct border zone. Half of each batch of cells was grown in culture t o provide a control for cell morphology and viability. Six additional rats were injected with the culture medium alone. forty-eight hours af ter injection, LV slices were processed for histological (hematoxylin- eosin) and immunohistological (sarcomeric alpha-actinin and laminin st aining) techniques. Examination of serial sections from injected regio ns showed that grafted myocytes were harbored into the host LV myocard ium in all control animals and at the border zone in 50% of the infarc ted rats. Grafted cells were identified by their morphological charact eristics and an immunohistological pattern of loose myofibrillar organ ization similar to that seen in cells concomitantly grown in culture. Injection of the culture medium alone had no effect but allowed us to rule out needle-related injury. Conclusions These initial results sugg est the feasibility of transplanting allogeneic cardiomyocytes into th e border zone of MI areas, a prerequisite for this approach to success fully improve the function of ischemically damaged hearts.