Collagen synthesis by Duchenne myogenic clones: pathogenic implications for the disease

Myogenic cell clones were grown in triplicates from a 3-year-old boy with Duchenne muscular dystrophy and three normal control boys matched for age. The well-differentiated Duchenne myogenic clone had lower creatine kinase activity and lower MM isozyme than the control clones. Analysis of (3H)-proline incorporation demonstrated a 2.2-fold increase in (3H)-hydroxyproline released into the medium of Duchenne myogenic cell clones, whereas intracellular (3H)-hydroxyproline levels showed normal values. These results strongly suggest that the increased amount of collagen present in Duchenne dystrophic muscle is related to the primary defect of the disease and is not due to a secondary replacement fibrosis.