Forced lengthening contractions induced by electrical stimulation revealed a repeating pattern of necrotic and regenerating zones along the length of the same myofibre, highlighting the importance of the basement membrane in human muscle regeneration.
Does forced lengthening contraction induced by electrical stimulation allow for the observation of in vivo myogenesis in young healthy males?
This study provides detailed documentation of in vivo myogenesis in adult humans, highlighting the preservation and role of the basement membrane during skeletal muscle regeneration.
BACKGROUND: While muscle regeneration has been extensively studied in animal and cell culture models, in vivo myogenesis in adult human skeletal muscle has not been investigated in detail. METHODS: Using forced lengthening contractions induced by electrical stimulation, we induced myofibre injury in young healthy males. Muscle biopsies were collected from the injured leg 7 and 30 days after muscle injury and from the uninjured leg as a control. Immuno-stained single muscle fibres and muscle cross sections were studied by wide-field and confocal microscopy. Samples were also studied at the ultra-structural level by electron microscopy. RESULTS: Microscopy of single muscle fibres in 3 dimensions revealed a repeating pattern of necrotic and regenerating zones along the length of the same myofibre, characterised by extensive macrophage infiltration alongside differentiating myogenic progenitor cells and myotubes: the hallmarks of myogenesis. The myofibre basement membrane was preserved during these processes and interestingly was seen at a later stage as a second basement membrane surrounding the regenerating fibres. CONCLUSIONS: This is the first work to document in vivo myogenesis in humans in detail and highlights the importance of the basement membrane in the process of regeneration. In addition, it provides insight into parallels between the regeneration of adult skeletal muscle in mouse and man, confirming that this model may be a useful tool in investigating myofibre and matrix formation, as well as specific cell types, during regeneration from the perspective of human muscle.
Mackey et al. (Tue,) conducted a other in Healthy adult human skeletal muscle (n=7). Forced lengthening contractions induced by electrical stimulation vs. Uninjured leg was evaluated on Myofibre necrosis and regeneration characteristics. Forced lengthening contractions induced by electrical stimulation revealed a repeating pattern of necrotic and regenerating zones along the length of the same myofibre, highlighting the importance of the basement membrane in human muscle regeneration.