Fig. 2
Grafts formed by 2 × 106 hMPCs with and without iNMES. The presence of human muscle fibers in murine hindlimbs was evaluated at 4 weeks post-transplantation. An antibody specific for human β-spectrin was used to stain cross sections of grafts by immunofluorescence; antibodies to desmin were used to stain both murine and human muscle fibers. The results show more human β-spectrin-positive myofibers (green), of larger size and in denser packing, in the grafts of mice treated with iNMES (group 3; B1, B4, B5) compared with untreated mice (group 2; A1, A4, A5). White arrows in A1 and A2 indicate a region of endogenous murine muscle that persisted following X-irradiation and CTX treatments. All cells labeled with antibodies to human β-spectrin in both groups 2 and 3 labeled with antibodies to desmin (red in merged images, A2 and B2, respectively), confirming their identity as myofibers. A3 and B3 show the boxed areas in A2 and B2 at higher magnification. A4 and A5, and B4 and B5, show muscle fibers of human regions of two other grafts from mice treated without (A4, A5) and with (B4, B5) iNMES. Scale bars = 50 μm