Tendon‐derived extracellular matrix induces mesenchymal stem cell tenogenesis via an integrin/transforming growth factor‐β crosstalk‐mediated mechanism

Abstract

Treatment of tendon injuries is challenging. To develop means to augment tendon regeneration, we have previously prepared a soluble, low immunogenic (DNA‐free), tendon extracellular matrix fraction (tECM) by urea extraction of juvenile bovine tendons, which is capable of enhancing transforming growth factor‐β (TGF‐β) mediated tenogenesis in human adipose‐derived stem cells (hASCs). Here, we aimed to elucidate the mechanism of tECM‐driven hASC tenogenic differentiation in vitro, focusing on the integrin and TGF‐β/SMAD pathways. Our results showed that tECM promoted hASC proliferation and tenogenic differentiation in vitro based on tenogenesis‐associated markers. tECM also induced higher expression of several integrin subunits and TGF‐β receptors, and nuclear translocation of p‐SMAD2 in hASCs. Pharmacological inhibition of integrin‐ECM binding, focal adhesion kinase (FAK) signaling, or TGF‐β signaling independently led to compromised pro‐tenogenic effects of tECM and actin fiber polymerization. Additionally, integrin blockade inhibited tECM‐driven TGFBR2 expression, while inhibiting TGF‐β signaling decreased tECM‐mediated expression of integrin α1, α2, and β1 in hASCs. Together, these findings suggest that the strong pro‐tenogenic bioactivity of tECM is regulated via integrin/TGF‐β signaling crosstalk. Understanding how integrins interact with signaling by TGF‐β and/or other growth factors (GFs) within the tendon ECM microenvironment will provide a rational basis for an ECM‐based approach for tendon repair.

Rho/ROCK Inhibition Promotes TGF-β3-Induced Tenogenic Differentiation in Mesenchymal Stromal Cells

“…In these studies, ROCK inhibition resulted in decreased expression of tendon markers and less pronounced tenocyte-like morphology of MSC [20,21]. Indicating a connection between mechanobiology, Rho/ROCK, and the well-described tenogenic effect of TGF-β, more recently, ECM extract-induced tenogenic differentiation was shown to be mediated via integrin as well as TGF-β/Smad pathways [32]. Furthermore, synergistic effects of ROCK activation by surface topography and TGF-β2 on Smad phosphorylation and tenogenic differentiation were reported [33], which is 8 Stem Cells International consistent with similar synergistic effects observed in contexts such as chondrogenic [34] or lung fibroblast differentiation [35].…”

Nonwoven-based gelatin/polycaprolactone membrane loaded with ERK inhibitor U0126 for treatment of tendon defects

“…The KEGG analysis revealed that many signaling pathways were enriched, among which we found the focal adhesion, extracellular matrix (ECM)-receptor interaction, PI3K-Akt and TGF-beta signaling pathways were activated by U0126. These pathways, especially the TGF-beta signaling pathway, have been considered as important factors governing tenogenesis, tendon development, as well as tendon injury healing [ 32 – 35 ]. GDF6 stood out in our further analysis as it was an important member of TGF- β signaling which was significantly increased by U0126.…”

Natural, synthetic and commercially-available biopolymers used to regenerate tendons and ligaments

“…Collagen is often considered for TL scaffolds since it is an ECM-based biomaterial with excellent bioactivity [ 218 ]. Collagen can be extracted and processed by chemical treatments to form the bioactive scaffolds in TL regeneration.…”