The aim of this study was to optimize human muscle formation in vivo from implanted human muscle precursor cells. We transplanted donor muscle precursor cells (MPCs) prepared from postnatal or fetal human muscle into immunodeficient host mice and showed that irradiation of host muscle significantly enhanced muscle formation by donor cells. The amount of donor muscle formed in cryodamaged host muscle was increased by exposure of donor cells to growth factors before their implantation into injured host muscle. Insulin-like growth factor type I (IGF-I) significantly increased the amount of muscle formed by postnatal human muscle cells, but not by fetal human MPCs. However, treatment of fetal muscle cells with IGF-I, in combination with basic fibroblast growth factor and plasmin, significantly increased the amount of donor muscle formed. In vivo, human MPCs formed mosaic human-mouse muscle fibers, in which each human myonucleus was associated with a zone of human sarcolemmal protein spectrin.

Arylboronic acids and some of their derivatives have been found to undergo a rapid boron-lead exchange with lead tetra-acetate. In the presence of a catalytic amount of mercury(it) acetate, the reaction produces mainly the aryl-lead triacetate, and it has been developed as a convenient method for in situ generation of these useful electrophilic C-arylating reagents. The reaction allows the generation for the first time of meta-and para-phenylenebis( lead triacetate), compounds which behave as meta-and para-phenylene dication equivalents.

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