Infantile-acute acid maltase deficiency (Pompe's disease): studies of muscle cultures.

Muscle was cultured from a 7-month-old boy affected by generalized weakness, macroglossia, cardiomegaly, hepatomegaly and increasing dyspnea. Muscle biopsy showed a vacuolar myopathy with glycogen accumulation (Pompe's disease). The muscle was cultured to verify whether the abnormality could be expressed in culture during myogenesis. In the living muscle cultures, phase-contrast microscopy revealed that myotubes as young as two weeks were vacuolated and that the vacuolization was higher in the older cultures compared to parallel control cultures. Fluorescent microscopy by acridine orange staining of the cultures showed a marked increase in acridine orange positive material (presumptive lysosomes) throughout the sarcoplasm. Electron microscopic data revealed myofibrillar destruction in the muscle biopsy and vacuolized cytoplasm in the Schwann cells. Cytochemically, the patient's myotubes stained very intensely for acid phosphatases. The increased acid phosphatase activity was quantitatively confirmed by cytophotometric evaluation performed on patient and control parallel myotubes. This is the first evidence that an increase in acid phosphatases has been quantitatively demonstrated in cultured muscle from a patient with acute infantile onset acid maltase deficiency (Pompe's disease) although the enzymatic activity was assayed at only one time of incubation.