Proteomics identifies differences in fibrotic potential of extracellular vesicles from human tendon and muscle fibroblasts

Abstract

Background Fibroblasts are the powerhouses responsible for the production and assembly of extracellular matrix (ECM). Their activity needs to be tightly controlled especially within the musculoskeletal system, where changes to ECM composition affect force transmission and mechanical loading that are required for effective movement of the body. Extracellular vesicles (EVs) are a mode of cell-cell communication within and between tissues, which has been largely characterised in cancer. However, it is unclear what the role of healthy fibroblast-derived EVs is during tissue homeostasis. Methods Here, we performed proteomic analysis of small EVs derived from primary human muscle and tendon cells to identify the potential functions of healthy fibroblast-derived EVs. Results Mass spectrometry-based proteomics revealed comprehensive profiles for small EVs released from healthy human fibroblasts from different tissues. We found that fibroblast-derived EVs were more similar than EVs from differentiating myoblasts, but there were significant differences between tendon fibroblast and muscle fibroblast EVs. Small EVs from tendon fibroblasts contained higher levels of proteins that support ECM synthesis, including TGFβ1, and muscle fibroblast EVs contained proteins that support myofiber function and components of the skeletal muscle matrix. Conclusions Our data demonstrates a marked heterogeneity among healthy fibroblast-derived EVs, indicating shared tasks between EVs of skeletal muscle myoblasts and fibroblasts, whereas tendon fibroblast EVs could play a fibrotic role in human tendon tissue. These findings suggest an important role for EVs in tissue homeostasis of both tendon and skeletal muscle in humans.

Extracellular vesicles: Critical players during cell migration

“…Fibronectin and laminins can also be carried by large EVs where, in association with the ECM crosslinking molecule tissue transglutaminase 2 (TG2), they have been shown to enhance focal adhesion kinase (FAK) activation and trophoblast cell migration (Antonyak et al, 2011;Desrochers et al, 2016;Hur et al, 2021). As a variety of ECM components have been identified to be associated with EVs (Jimenez et al, 2019;Rilla et al, 2019;Yeung et al, 2020), an interesting future direction will be to determine whether the presentation of ECM molecules by EVs is a general mechanism that promotes adhesion formation by diverse types of migrating cells.…”

Tendon and multiomics: advantages, advances, and opportunities

“…Although fewer studies are available so far, the proteome of extracellular vesicles in tenocytes is enriched in collagens, TGFβ1, and cytoskeletal proteins when compared to myofibroblasts, leading the authors to conclude that these vesicles could improve collagen synthesis and ECM assembly, potentially a good resource for regenerative therapies 70 .…”

Understanding extracellular vesicle and nanoparticle heterogeneity: Novel methods and considerations

“…Integrin α6 [80] be exclusive to those tissues, neural cell adhesion molecule (NCAM), for example, is considered a neuronal marker but may also be found in endocrine and muscle tissues [71]. The lack of a definitive cellspecific EV markers and the variability of EVs from different cell types contributes to further EV heterogeneity in more complex environments such as biofluids or tissue samples making attribution of an EV to a specific cell type difficult.…”