EFFICACY OF AUTOLOGOUS MYOGENIC PRECURSOR CELL TRANSPLANTATION IN PIGS FOLLOWING INTRAMUSCULAR INJECTION.

Abstract

P677 Aims: Myogenic precursor cell (MPC) transplantation is a widely investigated cell therapy technique for the potential treatment of muscle injury, cardiac failure and inherited myopathies. Early MPC death after injection is a major hurdle to overcome. Many groups described increased MPC survival in mice but with conditions not applicable in human settings. The use of a large animals model such as pig can help to define MPC transplantation strategies applicable in clinic. In this study, we analyzed the survival and efficacy of autologous MPC’s injection into intact porcine muscles. Methods: MPC’s were isolated and characterized using specific markers for CD56, desmin, and troponin T. To follow cell survival, MPC’s were labeled with tritiated (3H) thymidine. For histological analysis, freshly isolated MPC’s were transduced with a beta-galactosidase (beta-Gal) gene. A biopsy was performed at the implanted sites up to 5 days after injection for measurement of the remaining 3H scintillation rate, and at 8 days for histological analysis of beta-Gal+ myofibers. Results: Our isolation procedure allowed us to reach a yield of 898.1 ± 221.2 cells per mg of muscle. After 8 days in culture, MPC’s were characterized by FACS. 78.2 ± 4 % of the cells were CD56+ and 51.4 ± 13.3% were desmin+ (n=5). These myogenic properties were confirmed by an index of fusion (64.9 ± 2.7% of the nuclei formed myotubes). 24 h after transplantation, 60.5 ± 10.4 % of injected pig MPC’s survived but this survival rate decreased to 9.7 ± 2.3 % at 5 days after implantation (Figure 1, n = 10). Histological analysis showed the presence of beta-Gal+ cell nuclei in regenerating myotubes at 8 days in vivo (Figure 2).FigureFigure 2FigureConclusions: Our results show a significant increase in the early donor-cell survival (compared to the present literature). These data indicate that autologous MPC transplantation in pigs represents a step towards a better designing of myoblast transplantation strategies in humans. Nevertheless, only 10% of injected MPC’s survived at 5 days post-injection. We believe that immune response, inflammation and loss of “histocompatibility” can be responsible of the early cell death. Further experiments implying transduction of MPC’s with gene coding for anti-apoptotic molecules (like HO-1) or growth factors (like IGF-1) can represent a promising strategy to prevent MPC loss in vivo.