Cultured inclusion-body myositis muscle fibers do not accumulate beta-amyloid precursor protein and can be innervated

Cultured muscle fibers from patients with sporadic inclusion-body myositis (s-IBM), similar to normal control muscle fibers, 1) did not have beta-amyl oid precursor protein (beta APP) immunoreactivity; and 2) became normally i nnervated, as evidenced by the following features: full cross-striation, co ntinuous contraction, and acetylcholinesterase and acetylcholine receptors accumulated only at neuromuscular junctions. Thus, factors responsible for beta APP accumulation and denervation-like changes in s-IBM muscle biopsies are not operative in the relatively short-term, non-aged, cultured s-IBM m uscle fibers.