BMP‐2 stimulated non‐tenogenic differentiation and promoted proteoglycan deposition of tendon‐derived stem cells (TDSCs) in vitro

We hypothesized that BMP‐2 might induce non‐tenocyte differentiation and increase production of proteoglycans of tendon‐derived stem cells (TDSCs). This study investigated the effects of BMP‐2 on the differentiation and production of proteoglycans in TDSCs in vitro. Rat patellar TDSCs were treated without or with BMP‐2. The osteogenic, adipogenic, chondrogenic, and tenogenic differentiation of TDSCs were assessed by (1) Alizarin red‐S staining assay; (2) Oil Red‐O staining assay; (3) haematoxylin–eosin staining, Safranin‐O staining, immunohistochemical staining of Sox9, and collagen type II; and (4) qRT‐PCR analysis of lineage‐specific markers. The production of glycoaminoglycans (GAG) in the BMP‐2‐treated TDSCs was assessed by alcian blue staining. The mRNA expression of aggrecan (Acan), decorin (Dcn), biglycan (Bgn), and fibromodulin (Fmod) in TDSCs after BMP‐2 treatment was assessed by qRT‐PCR. BMP‐2 promoted the osteogenic, adipogenic, and chondrogenic differentiation but inhibited tenogenic marker expression of TDSCs. GAG production and Acan increased while Dcn, Bgn, and Fmod decreased in TDSCs after BMP‐2 stimulation. In conclusion, BMP‐2 promoted GAG deposition, aggrecan expression, and enhanced non‐tenocyte differentiation of TDSCs in vitro. The effect of BMP‐2 on TDSCs might provide insights into the histopathological changes of tendinopathy. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31: 746–753, 2013