Acetylcholine receptors and acetylcholinesterase accumulate at the nerve-muscle contacts of de novo grown human monolayer muscle cocultured with fetal rat spinal cord.

Adult human biopsied muscle grown de novo from myoblasts in monolayer was cocultured with spinal cord explants of 13- to 14-day-old rat embryos. Cocultures were established 15 days after myoblast fusion. Autoradiography of 125I-alpha-bungarotoxin and acetylcholinesterase staining were carried out on 27- to 56-day-old muscle-cord cocultures. Large clusters of 125I-alpha-bungarotoxin, indicating clusters of acetylcholine receptors, were present at nerve-muscle contacts but not elsewhere on the muscle fibers. Accumulation of acetylcholinesterase was also present at nerve-muscle contacts. This study demonstrates that monolayer cultured adult human muscle can be innervated by embryonic rat spinal cord neurons and thus there is no requirement for an original basal lamina tube as it is present when organ-cultured human muscle is innervated.