Telocytes in skeletal muscle: Emerging players in homeostasis and repair/regeneration.

Telocytes (TCs) have recently emerged as novel components of the skeletal muscle interstitium. They are distinguished from other stromal cells by their immunophenotypic profiles and, especially, unique ultrastructural traits. Specifically, TCs feature a small cell body and very long, thin telopodes with a moniliform appearance conferred by the alternation of slender segments (podomers) and small dilated portions (podoms). Experimental evidence suggests that, as part of the skeletal muscle stem cell niche, TCs may be involved in orchestrating satellite cell activation and myogenic differentiation through both direct physical interactions and paracrine signaling. Yet, further in-depth research is needed to uncover specific immunophenotypic signatures for skeletal muscle TCs within the niche, as well as to identify the signaling pathways by which they influence neighboring satellite cells and, possibly, other cellular components of the niche. In the present review, particular emphasis is placed on the putative strategic role of TCs in maintaining skeletal muscle tissue homeostasis, their involvement in muscle pathological alterations, and, most importantly, their possible role in the coordination of the regenerative response following injury. In perspective, the promising therapeutic potential of TC-based strategies to enhance skeletal muscle tissue repair/regeneration and restrain post-injury fibrosis is also discussed.