Hypertrophic differentiation during chondrogenic differentiation of progenitor cells is stimulated by BMP-2 but suppressed by BMP-7

• Published in: Osteoarthritis and cartilage Vol. 21; no. 4; pp. 604 - 613
• Main Authors: Caron, M.M.J, Emans, P.J, Cremers, A, Surtel, D.A.M, Coolsen, M.M.E, van Rhijn, L.W, Welting, T.J.M
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01-04-2013
• Subjects: Animals; Bapx1/Nkx3.2; Bone Marrow Cells - drug effects; Bone Morphogenetic Protein 2 - pharmacology; Bone Morphogenetic Protein 7 - pharmacology; Bone morphogenic protein 2; Bone morphogenic protein 7; Cell Differentiation - drug effects; Cell Differentiation - physiology; Cell Enlargement - drug effects; Cells, Cultured; Chondrocytes - cytology; Chondrocytes - drug effects; Chondrocytes - pathology; Chondrogenesis - drug effects; Chondrogenic differentiation; Dose-Response Relationship, Drug; Homeodomain Proteins - physiology; Humans; Hypertrophy; Progenitor cells; Rabbits; Rheumatology; Stem Cells - cytology; Stem Cells - drug effects; Transcription Factors - physiology; Bone morphogenic protein 7; Chondrogenic differentiation; Bapx1/Nkx3.2; Progenitor cells; Bone morphogenic protein 2
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2013.01.009

Summary Objective Bone morphogenic protein (BMP)-2 and BMP-7 are clinically approved and their recombinant proteins are used for bone tissue regenerative purposes and widely evaluated for cartilage regeneration. Previous comparison of the in vitro chondrogenic characteristics of BMP-2 vs BMP-7 did not address hypertrophic differentiation and characterizing their chondrogenic properties with a focus in on chondrocyte hypertrophy was topic of investigation in this study. Design Equimolar concentrations of BMP-2 or BMP-7 were added to chondrogenic differentiating ATDC5, human bone marrow stem cells or rabbit periosteal explants. Expression of Col2a1, Sox9, Acan, Col10a1, Runx2, ALP, Mmp13, Mef2c and Bapx1/Nkx3.2 was determined by reverse transcription-quantitative PCR (RT-qPCR) and immunoblotting. Glycosaminoglycan content, cell proliferation capacity and ALP activity were analysed by colourimetric analyses. Expression of Bapx1/Nkx3.2 and Sox9 was targeted by transfection of target specific siRNA duplexes. Results BMP-2 dose-dependently increased chondrocyte hypertrophy during chondrogenic differentiation of progenitor cells, whereas BMP-7 acted hypertrophy-suppressive and chondro-promotive. Both BMPs did not influence cell proliferation, but they did increase total glycosaminoglycan content. In a candidate approach Bapx1/Nkx3.2 was found to be involved in the BMP-7 mediated suppression of chondrocyte hypertrophy in ATDC5 cells. Conclusions BMP-2 and BMP-7 display opposing actions on the chondrogenic outcome of differentiating progenitor cells: BMP-2 acts a specific inducer of chondrocyte hypertrophy, while BMP-7 appears to increase or maintain chondrogenic potential and prevent chondrocyte hypertrophy. Our results pave the way for an application-dependent differential use of BMP-2 or BMP-7.