Interesting new work published in The American Journal of Physiology- Cell Physiology evaluated the ability of muscle-derived pericyte to contribute to skeletal muscle remodeling in response to training. The researchers used electric stimulation to contract muscles and monitor the response of pericyte cells. They found that the CD146+ Lin- pericyte cells were the most sensitive to contraction and they contribute to upregulating ECM remodeling and angiogenesis. This figure shows the collagen I content in the control groups was similar to the CD146+ group (top). Then they used F-CHPs to examine the amount of collagen degradation after e-stim (bottom). They saw even with similar collagen content to start, only the CD146+ group resulted in much higher levels of collagen damage due to ECM remodeling.
Abstract: Unaccustomed resistance exercise can initiate skeletal muscle remodeling and adaptive mechanisms that can confer protection from damage and enhanced strength with subsequent stimulation. The myofiber may provide the primary origin for adaptation, yet multiple mononuclear cell types within the surrounding connective tissue may also contribute. The purpose of this study was to evaluate the acute response of muscle-resident interstitial cells to contraction initiated by electrical stimulation (e-stim), and subsequently determine the contribution of pericytes to remodeling as a result of training. Mice were subjected to bilateral e-stim or sham treatment. Following a single session of e-stim, NG2+CD45-CD31- (NG2+Lin-) pericyte, CD146+Lin- pericyte, and PDGFRα+ fibroadipogenic progenitor cell quantity and function were evaluated via multiplex flow cytometry and targeted qPCR. Relative quantity was not significantly altered 24 hours post-contraction, yet unique gene signatures were observed for each cell population at 3 hours post-contraction. CD146+Lin- pericytes appeared to be most responsive to contraction, and upregulation of genes related to immunomodulation and extracellular matrix (ECM) remodeling was observed via RNA sequencing. Intramuscular injection of CD146+Lin- pericytes did not significantly increase myofiber size, yet enhanced ECM remodeling and angiogenesis in response to repeated bouts of e-stim for 4 weeks. The results from this study provide the first evidence that CD146+Lin- pericytes are responsive to skeletal muscle contraction and may contribute to the beneficial outcomes associated with exercise.
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