Rho/ROCK Inhibition Promotes TGF- β 3-Induced Tenogenic Differentiation in Mesenchymal Stromal Cells

Michaela Melzer; Susanna Schubert; Simon Franz Müller; Joachim Geyer; Alina Hagen; Sabine Niebert; Janina Burk

doi:10.1155/2021/8284690

Rho/ROCK Inhibition Promotes TGF- β 3-Induced Tenogenic Differentiation in Mesenchymal Stromal Cells

Stem Cells Int. 2021 Oct 8:2021:8284690. doi: 10.1155/2021/8284690. eCollection 2021.

Authors

Michaela Melzer¹, Susanna Schubert^{2

3}, Simon Franz Müller⁴, Joachim Geyer⁴, Alina Hagen¹, Sabine Niebert¹, Janina Burk¹

Affiliations

¹ Equine Clinic (Surgery, Orthopedics), Faculty of Veterinary Medicine, Justus-Liebig-University Giessen, 35392 Giessen, Germany.
² Saxon Incubator for Clinical Translation, University of Leipzig, 04103 Leipzig, Germany.
³ Institute of Human Genetics, University of Leipzig Hospitals and Clinics, 04103 Leipzig, Germany.
⁴ Biomedical Research Center Seltersberg (BFS), Institute of Pharmacology and Toxicology, Faculty of Veterinary Medicine, Justus-Liebig-University Giessen, 35392 Giessen, Germany.

Abstract

Mesenchymal stromal cells (MSC) represent a promising therapeutic tool for tendon regeneration. Their tenogenic differentiation is crucial for tissue engineering approaches and may support their beneficial effects after cell transplantation in vivo. The transforming growth factor (TGF)-β, signalling via intracellular Smad molecules, is a potent paracrine mediator of tenogenic induction. Moreover, scaffold topography or tendon matrix components induced tenogenesis via activation of the Rho/ROCK cascade, which, however, is also involved in pathological adaptations in extracellular matrix pathologies. The aim of this study was to investigate the interplay of Rho/ROCK and TGF-β3/Smad signalling in tenogenic differentiation in both human and equine MSC. Primary equine and human MSC isolated from adipose tissue were cultured as monolayers or on tendon-derived decellularized scaffolds to evaluate the influence of the ROCK inhibitor Y-27632 on TGF-β3-induced tenogenic differentiation. The MSC were incubated with and without TGF-β3 (10 ng/ml), Y-27632 (10 μM), or both. On day 1 and day 3, the signalling pathway of TGF-β and the actin cytoskeleton were visualized by Smad 2/3 and phalloidin staining, and gene expression of signalling molecules and tendon markers was assessed. ROCK inhibition was confirmed by disruption of the actin cytoskeleton. Activation of Smad 2/3 with nuclear translocation was evident upon TGF-β3 stimulation. Interestingly, this effect was most pronounced with additional ROCK inhibition in both species (p < 0.05 in equine MSC). In line with that, the tendon marker scleraxis showed the strongest upregulation when TGF-β3 and ROCK inhibition were combined (p < 0.05 in human MSC). The regulation pattern of tendon extracellular matrix components and the signalling molecules TGF-β3 and Smad 8 showed differences between human and equine MSC. The obtained results showed that ROCK inhibition promotes the TGF-β3/Smad 2/3 axis, with possible implications for future MSC priming regimes in tendon therapy.