Yields of muscle from myogenic cells implanted into young and old mdx hosts.

Implantation of normal muscle precursor cells (mpc) for treatment for inherited myopathies such as Duchenne muscular dystrophy is in clear need of improvement to become practicable, but few variables have been studied comparatively. Here, we report the first quantitative estimate of the effectiveness of implanting mpc into preirradiated muscles of young and old mice and into preirradiated and nonirradiated old muscles. Estimates were made of the amount of muscle formed by injection of 5 x 10(5) cells dissociated from neonatal normal mouse muscle into tibialis anterior muscles of the dystrophin-deficient mdx mouse. We show that normal mpc are incorporated slightly more efficiently into muscles of young than old host mice, to form some 10 mg of dystrophin-positive fibers. In older muscles, prior irradiation has little effect on the total yield of new muscle.