Enhanced migration and fusion of donor myoblasts in dystrophic and normal host muscle

Sliced male C57Bl/10Sn (H2‐b) donor muscles were grafted into the female histocompatible muscles of untreated, FK506‐treated, and T‐cell depleted (with or without thymic tolerization) dystrophic (mdx; H2‐b) and normal (C57Bl/10Sn; H2‐b) hosts, and also into histoincompatible normal (Balb/c; H2‐d) hosts. The fate of male donor nuclei was monitored on tissue sections by in situ hybridization with a Y‐chromosome specific probe. The results demonstrate that the dystrophic environment is more conducive than normal muscle to donor myoblast migration, with the distance moved being threefold greater at 12 weeks in dystrophic hosts. T‐cell depletion was significantly more effective than FK506 treatment at enhancing donor myoblast emigration in both histocompatible and histoincompatible hosts at 3 weeks. Furthermore, the effects of T‐cell depletion were sustained in histoincompatible hosts at 12 weeks. These data endorse the use of host T‐cell depletion as a promising long‐term strategy to improve myoblast transfer therapy (MTT) in the clinical situation. © 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 560–574, 2000.