{
  "id": 10406859,
  "title": "Fibro-adipogenic Progenitor and Macrophage Remodeling of the Aging Skeletal Muscle Niche During Exercise-Induced Hypertrophy",
  "url": "https://urgent.news/2026/09/28/fibro-adipogenic-progenitor-and-macrophage-remodeling-of-the-aging",
  "topic": "science",
  "section": "Science",
  "published": "2026-09-28T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.09.25.754304v1?rss=1"
  },
  "original_language": "en",
  "account": "Fibro-adipogenic progenitors (FAPs) and macrophages play crucial roles in the remodeling of the skeletal muscle niche during exercise-induced hypertrophy in older individuals. Through six weeks of blood flow restricted resistance exercise (BFRRE), the study found significant enlargement of both FAPs and muscle stem cells (MuSCs), indicating an adaptive response to exercise. Flow cytometry analysis revealed a shift in the FAP population towards a higher proportion of CD90high FAPs, without changing the total FAP count. This phenotypic shift was associated with the enrichment of promyogenic factors in CD90high FAPs compared to CD90low FAPs. In vitro studies using fresh FAP isolates demonstrated that CD90high FAPs promote myotube growth more effectively than CD90low FAPs, suggesting that the shift in FAP phenotype may facilitate muscle hypertrophy. Additionally, BFRRE increased the proportion of pro-inflammatory macrophages (CD11c+) within the skeletal muscle niche, highlighting a dynamic immune response during adaptation. Interestingly, TNF, a pro-inflammatory cytokine, was shown to reduce the proliferation of human primary FAPs in vitro, suggesting that macrophage-derived signals may regulate excessive FAP expansion during tissue remodeling. These findings collectively provide new insights into how the remodeling of the cellular niche may support muscle hypertrophy in response to exercise, potentially offering a mechanism through which exercise supports hypertrophy in older individuals.",
  "summary": "Fibro-adipogenic progenitors (FAPs) have emerged as central regulators of the skeletal muscle homeostasis and the muscle microenvironment. However, the role of FAPs in the context of exercise-induced muscle hypertrophy remains largely unexplored. Here, we utilized six weeks of blood flow restricted resistance exercise (BFRRE) to study cellular adaptations within the muscle microenvironment…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}