From fibro/adipogenic progenitors to adipocytes: Understanding adipogenesis in muscle degeneration for disease modulation.

Fibro/adipogenic progenitors (FAPs) are muscle-resident stem cells essential for muscle regeneration because of their ability to differentiate into adipocytes and fibroblasts. This differentiation contributes to tissue remodelling and is implicated in the accumulation of fat and fibrotic tissue seen in neuromuscular, cardiovascular and degenerative diseases. FAPs also interact with other muscle cells and modulate inflammation, playing a central role in muscle degeneration across various disease contexts. This review summarises current knowledge on FAP adipogenic differentiation in muscle degeneration and regeneration, with a focus on cardiovascular and neuromuscular diseases, which share common features of impaired muscle remodelling. We discuss established methods for culturing, maintaining, and differentiating FAPs in vitro to support future research. Additionally, we examine FAP subpopulations, key signalling pathways and pharmacological agents influencing FAP differentiation into adipocytes. Understanding these mechanisms offers promising avenues for developing therapeutic strategies to restore muscle homeostasis and slow down pathological muscle remodelling.