title: Uniaxial mechanical tension promoted osteogenic differentiation of rat tendon-derived stem cells (rTDSCs) via the Wnt5a-RhoA pathway.
abstract: Chronic tendinopathy is a tendon disorder that is common in athletes and individuals whose tendons are subjected to repetitive strain injuries. The presence of ossification worsened the clinical manifestation of the disorder. The change of tendon loading due to mechanical overload, compression, or disuse have been implicated as the possible etiologies, but the pathological mechanisms of tendinopathy remain unclear. In this study, we demonstrated that ossification in tendon tissue might be due to the osteogenesis of tendon-derived stem cells (TDSCs) induced by uniaxial mechanical tension (UMT) which mimics the mechanical loading in tendon. Rat TDSCs (rTDSCs) could be induced to differentiate into osteogenic lineage after treatment with 2% elongation UMT for 3 days as shown by the increased expression Runx2 mRNA and protein, Alpl mRNA, collagen type 1 alpha 1 (Col1a1) mRNA, ALP activity, and ALP cytochemical staining. RhoA, an osteogenesis regulator, was activated in rTDSCs upon UMT stimulation. Blockage of RhoA activity in rTDSCs by C3 toxin or ROCK activity, a downstream target of RhoA, by Y-27632 inhibited UMT-induced osteogenesis in rTDSCs. UMT up-regulated the mRNA expression of Wnt5a but not the other non-canonical Wnts. The inhibition of Wnt5a expression by siRNA abolished UMT-induced Runx2 mRNA expression and RhoA activation in rTDSCs and the inhibition of Runx2 expression could be rescued by addition of LPA, a RhoA activator. In conclusion, our results showed that UMT induced osteogenic differentiation of rTDSCs via the Wnt5a-RhoA pathway, which might contribute to ectopic ossification in tendon tissue due to mechanical loading.
authors.affiliation: The Key Laboratory of Stem Cell Biology, Institute of Health Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences (CAS) & Shanghai Jiao Tong University School of Medicine (SJTUSM), Shanghai, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.forename: Yujie
authors.initials: Y
authors.lastname: Fu
authors.forename: Wenxue
authors.initials: W
authors.lastname: Tong
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Geng
authors.forename: Pauline Po Yee
authors.initials: PP
authors.lastname: Lui
authors.forename: Tingting
authors.initials: T
authors.lastname: Tang
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Zhang
authors.forename: Kerong
authors.initials: K
authors.lastname: Dai
mesh_terms: D000469:Alkaline Phosphatase / Q000235:genetics / Q000378:metabolism; D000577:Amides / Q000494:pharmacology; D000818:Animals; D001696:Biomechanical Phenomena; D002454:Cell Differentiation; D019070:Cell Lineage; D002478:Cells, Cultured; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D008297:Male; D009999:Ossification, Heterotopic / Q000378:metabolism / Q000473:pathology*; D010012:Osteogenesis; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013194:Staining and Labeling / Q000379:methods; D013234:Stem Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D013314:Stress, Mechanical; D052256:Tendinopathy / Q000378:metabolism / Q000473:pathology; D013710:Tendons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D051153:Wnt Proteins / Q000378:metabolism; D060449:Wnt Signaling Pathway; D000071818:Wnt-5a Protein; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000378:metabolism
chemical_list: D000577:Amides; C000716129:Col1a1 protein, rat; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D050659:Core Binding Factor Alpha 1 Subunit; D008246:Lysophospholipids; D011725:Pyridines; D012333:RNA, Messenger; C493717:Runx2 protein, rat; D051153:Wnt Proteins; D000071818:Wnt-5a Protein; C491837:Wnt5a protein, rat; C108830:Y 27632; D000469:Alkaline Phosphatase; D020742:rhoA GTP-Binding Protein; C032881:lysophosphatidic acid