Rhabdomyosarcoma ρ0 cells: Isolation and characterization of a mitochondrial DNA depleted cell line with 'muscle-like' properties

Mutations of mitochondrial DNA are a significant cause of neuromuscular disease. Pathological mutant mitochondrial DNA has been studied in control nuclear backgrounds. These experiments entailed transfer of patient-derived mitochondria to ρ⁰ cells that lack mtDNA. A limitation of these studies has been the fact that the control nuclear backgrounds were unrelated to the affected tissues of patients. Therefore a rhabdomyosarcoma cell line that has 'muscle-like' properties was tested to determine whether it could be depleted of mtDNA. A human rhabdomyosarcoma cell line was treated with the DNA intercalating dye ethidium bromide (3,8-diamino-5-ethyl-6-phenylphenanthridinium bromide) for 45 days. The treatment induced complete and permanent loss of mitochondrial DNA (ρ⁰) in the rhabdomyosarcoma cells, as mtDNA remained undetectable after 8 months of growth in medium without drug. Crucially, the rhabdomyosarcoma ρ⁰ cells retained the ability to differentiate into myotubes with expression of muscle specific isoenzymes. The rhabdomyosarcoma ρ⁰ cell line provides a model system for studying pathological mutant mtDNA in cells that more closely resemble human muscle than the hitherto available human ρ⁰ cell lines. Copyright (C) 2000 Elsevier Science B.V.