title: Mechanical loading increased BMP-2 expression which promoted osteogenic differentiation of tendon-derived stem cells.
abstract: This study aimed to investigate the effect of repetitive tensile loading on the expression of BMP-2 and the effect of BMP-2 on the osteogenic differentiation of tendon-derived stem cells (TDSCs) in vitro. Repetitive stretching was applied to TDSCs isolated from rat patellar tendon at 0%, 4%, and 8%, 0.5 Hz. The expression of BMP-2 was detected by Western blotting and qPCR. To study the osteogenic effects of BMP-2 on TDSCs, BMP-2 was added to the TDSC monolayer for the detection of ALP activity and calcium nodule formation in a separate experiment. TDSCs adhered, proliferated, and aligned along the direction of externally applied tensile force while they were randomly oriented in the control group. Western blotting showed increased expression of BMP-2 in 4% and 8% stretching groups but not in the control group. Up-regulation of BMP-2 mRNA was also observed in the 4% stretching group. BMP-2 increased the osteogenic differentiation of TDSCs as indicated by higher ALP cytochemical staining, ALP activity, and calcium nodule formation. Repetitive tensile loading increased the expression of BMP-2 and addition of BMP-2 enhanced osteogenic differentiation of TDSCs. Activation of BMP-2 expression in TDSCs during tendon overuse might provide a possible explanation of ectopic calcification in calcifying tendinopathy.
authors.affiliation: Faculty of Medicine, Department of Orthopaedics and Traumatology, The Chinese University of Hong Kong, Hong Kong SAR, China.
authors.forename: Yun Feng
authors.initials: YF
authors.lastname: Rui
authors.forename: Pauline Po Yee
authors.initials: PP
authors.lastname: Lui
authors.forename: Ming
authors.initials: M
authors.lastname: Ni
authors.forename: Lai Shan
authors.initials: LS
authors.lastname: Chan
authors.forename: Yuk Wa
authors.initials: YW
authors.lastname: Lee
authors.forename: Kai Ming
authors.initials: KM
authors.lastname: Chan
mesh_terms: D053687:Adult Stem Cells / Q000166:cytology* / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics* / Q000494:pharmacology; D002114:Calcinosis / Q000473:pathology / Q000503:physiopathology; D002454:Cell Differentiation / Q000502:physiology; D002478:Cells, Cultured; D012090:Cumulative Trauma Disorders / Q000473:pathology / Q000503:physiopathology; D015870:Gene Expression / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D052256:Tendinopathy / Q000473:pathology / Q000503:physiopathology*; D013710:Tendons / Q000166:cytology*; D013718:Tensile Strength / Q000502:physiology; D016474:Weight-Bearing / Q000502:physiology*
chemical_list: C525720:Bmp2 protein, rat; D055396:Bone Morphogenetic Protein 2