Longevity & AgingFAPs and Macrophages Team Up to Repair Aging Muscle After Injury
Aging impairs skeletal muscle's ability to regenerate after injury, but the cellular mechanisms in humans remain poorly understood. Researchers used spatial RNA sequencing, single-cell transcriptomics, flow cytometry, and functional assays to map the regenerative landscape in elderly human muscle biopsies taken before and 2, 8, and 30 days after electrically induced injury. They identified fibro-adipogenic progenitors (FAPs) and macrophages as the central coordinators of repair, discovering that FAPs secrete complement factor C3 to enhance macrophage phagocytosis, survival, and metabolism. This FAP-to-macrophage signaling axis represents a previously uncharacterized communication pathway in human aged muscle and opens new avenues for therapeutic strategies to counter age-related regenerative decline.
