DEGENERATION OF COCULTURES OF SPINAL MUSCULAR-ATROPHY MUSCLE-CELLS AND RAT SPINAL-CORD EXPLANTS IS NOT DUE TO SECRETED FACTORS AND CANNOT BE PREVENTED BY NEUROTROPHINS

We have shown recently that cocultures of muscle cells from infantile spinal muscular atrophy (SMA) patients innervated by motoneurons of no rmal rat spinal cord explants undergo a degeneration process, suggesti ng that muscle may play a role in this atrophy, which previously has b een considered to be a pure motoneuron disease. Conditional media of S MA cocultures did not affect control healthy nerve muscle cocultures. Conversely, conditioned media of control cocultures were unable to pre vent degeneration of SMA cocultures. Moreover, neurotrophic factors, t hought to be of help in motoneuron disease treatment, did not protect SMA cocultures from premature death. Our results suggest that the abno rmal phenotype observed in nerve-muscle coculture (1) is not due to th e release of a toxic factor nor to the lack of a secreted survival fac tor; and (2) does not respond to neurotrophin treatment. (C) 1997 John Wiley & Sons, Inc.