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Phagocytic capacity of human muscle fibers
1Department of Neurology, Medical Academy, Warsaw, Poland.
Abstract:
Isolated dead muscle cell fragments (apoptotic bodies [ABs]) were investigated by electron microscopy in different stages of phagocytosis. Phagocytosis of ABs was carried out by neighboring muscle cells. The mechanism of internalization took place in both mature and immature muscle cells and consisted of the progressive engulfment of ABs within cytoplasmic vacuoles and craters. In addition, concentrated microfilaments formed a dense ring in the muscle cytoplasm adjacent to the engulfed ABs. The above combination of membrane evagination and phagocytic vacuole formation as well as the extensive microfilament organization at the site of AB engulfment were analogous to the cytoplasmic response seen in the tissue of mononuclear phagocytic cells.
Insights
Neighboring muscle cells engulf dead cell fragments (apoptotic bodies) through a process involving membrane evagination and microfilament rings. This phagocytosis mechanism is similar to that observed in mononuclear phagocytic cells.
Area of Science:
- Cell Biology
- Muscle Physiology
- Cellular Dynamics
Background:
- Muscle cells undergo programmed cell death, resulting in apoptotic bodies.
- Efficient clearance of cellular debris is crucial for tissue homeostasis and regeneration.
Purpose of the Study:
- To investigate the mechanism by which neighboring muscle cells phagocytose isolated dead muscle cell fragments (apoptotic bodies).
- To characterize the cellular response during the engulfment of apoptotic bodies by muscle cells.
Main Methods:
- Electron microscopy was used to examine apoptotic bodies at various stages of phagocytosis.
- Analysis focused on the interaction between phagocytosing muscle cells and apoptotic bodies.
Main Results:
- Muscle cells, both mature and immature, were observed to engulf apoptotic bodies.
- Engulfment occurred via progressive internalization into cytoplasmic vacuoles and craters.
- A dense ring of microfilaments formed in the muscle cytoplasm adjacent to the engulfed apoptotic bodies.
- The observed phagocytosis mechanism showed analogies to mononuclear phagocytic cells.
Conclusions:
- Muscle cells actively participate in clearing their own dead fragments through phagocytosis.
- The process involves membrane dynamics and significant cytoskeletal reorganization (microfilaments).
- This cellular mechanism highlights a conserved phagocytic response across different cell types.