Single-cell RNA sequencing reveals cellular composition of fibrotic fascia associated with gluteal muscle contracture
Fibrosis is a common and integral pathological feature in various chronic diseases, capable of affecting any tissue or organ. Fibrosis within deep fascia is implicated in many myofascial disorders, including gluteal muscle contracture (GMC), Dupuytren's disease, plantar fasciitis, iliotibial band syndrome, and chronic muscle pain. In this study, we performed scRNA seq analysis on fibrotic fascia associated with GMC and compared them to nonfibrotic control fascial samples. Our findings show that fibroblast and macrophage cells play a role in pathological tissue remodeling within fibrotic deep fascia. We observed an upregulation of various collagens, proteoglycans, and extracellular matrix (ECM) glycoproteins in contracture deep fascia, attributed to the widespread activation of fibroblast subclusters. Additionally, two pro fibrotic macrophage subpopulations, SPP1+ MP and ECM like MP, appear to facilitate ECM deposition in fibrotic deep fascia by either regulating fibroblast activation or directly contributing to ECM production. SPP1+ MP and ECM like MP cells, as well as the signal interaction between SPP1+ MP and fibroblast cells, present novel and potential therapeutic target for treating GMC and other related myofascial disorders. Overall design: To investigate the pathogenesis of deep fascial fibrosis, we obtained 10 fibrotic iliotibial band samples from patients with gluteal muscle contracture and 4 non-fibrotic iliotibial band samples from patients with femoral fracture.    Single cell sequencing was performed on 14 samples of iliotibial bands, and the single cell sequencing data of fibrotic and non-fibrotic iliotibial bands were compared and analyzed