Myoblast transplantation for cardiac repair: from automyoblast to allomyoblast transplantation.

Background: We sought to compare host immune cell kinetics, survival profile of donor skeletal myoblasts, and skeletal myoblast graft efficacy after autologous and allogeneic skeletal myoblast transplantation into a rat model of myocardial infarction.
Methods: One week after myocardial infarction, 128 animals were divided into four groups: group 1 (n = 24, receiving medium only), group 2 (n = 24, receiving medium and cyclosporine), group 3 (n = 40, autologous skeletal myoblast transplantation), and group 4 (n = 40, allogeneic skeletal myoblast transplantation with cyclosporine treatment). Rats were euthanized 10 minutes, 1 day, and 4, 7, and 28 days later. Host immune cell kinetics were assessed by immunohistochemical studies for macrophages, and CD4+ and CD8+ lymphocytes. Donor skeletal myoblast survival was confirmed by tracking prelabeled signals, and quantified by beta-gal assay. Heart function was evaluated by echocardiography.
Results: A transient immune cell infiltration was demonstrated in group 3, with macrophage infiltration on day 1 and day 4, CD8+ cell infiltration on day 4 and day 7, and CD4+ cell infiltration on day 4. In group 4, immunocyte infiltration was slightly more severe than that in group 3. Automyoblasts and allomyoblasts showed no significant difference of survival from day 1 to day 7 (p > 0.10); however, on day 28, automyoblasts showed better survival than allomyoblasts (p < 0.05). Transplantation of allomyoblasts increased systolic heart function and limited heart dilation after myocardial injury to a similar degree as automyoblasts (p > 0.10).
Conclusions: The use of allomyoblasts is feasible and effective for cardiac repair with immunosuppressive treatment as compared with automyoblasts.