INNERVATION OF MYOD-CONVERTED HUMAN AMNIOCYTES AND FIBROBLASTS BY FETAL RODENT SPINAL-CORD NEURONS

MyoD is one member of a gene family involved in the regulation of myog enesis. MyoD transfection induces myogenesis in a variety of non-muscl e cells. Human amniocytes and fibroblasts were infected with a MyoD-re trovirus vector, to determine whether the converted cells can mature n ormally to form functional muscle fibers. MyoD-converted cells were co cultured with fetal rat spinal cord. After 2-3 weeks of co-culture cro ss-striated, contracting muscle fibers were observed. Combined acetylc holinesterase cytochemistry and acetylcholine receptor labeling showed prominent staining at nerve-muscle contacts. Approximately half of th e total creatine kinase activity was due to the muscle-specific isozym e. Innervated MyoD-converted cells might represent a new source of mus cle cells for studying the molecular events leading toward the formati on of functional muscle. This system also appears suitable for studyin g the pathogenesis of hereditary, often rare, myopathies affecting mus cle-specific proteins, for which muscle tissue is frequently unavailab le for in vitro analysis.