Role of stromal cell-derived factor-1 alpha on endochondral ossification

Abstract

s / Osteoarthritis and Cartilage 20 (2012) S10–S53 S44 Sost mRNA suggesting that Sclerostin might be regulated by Wnt. We further observed an enhanced expression of Sclerostin in osteoarthritic cartilage compared to cartilage of control mice. Conclusions:We here show that Wnt3a increases the catabolic activity and inhibits the anabolic activity in murine chondrocytes. Sclerostin alleviates the expression of catabolic genes induced byWnt and rescued proteoglycan production. Moreover, Sclerostin promotes the cartilage maintenance through the inhibition of chondrocyte hypertrophy. Finally, the expression of Sclerostin expression in osteoarthritic mice suggests that Sclerostin might be involved in the pathophysiology in cartilage damage and might constitute a target for the prevention of osteoarthritis. 71 ROLE OF STROMAL CELL-DERIVED FACTOR-1 ALPHA ON ENDOCHONDRAL OSSIFICATION G. Kim , S. Han , Y. Jung , S. Usmani , V. Ulici , F. Beier . Daegu fatima Hosp., Daegu, Republic of Korea; 2 Lab. for arthritis and bone biology, Fatima research Inst., Daegu, Republic of Korea; Dept. of Physiology and Pharmacology, Univ. of Western Ontario, London, ON, Canada; CIHR Group in Skeletal Dev. and Remodeling, London, ON, Canada Purpose: The main cellular events of articular chondrocytes during osteoarthritis are a loss of the traits as permanent cartilage, and a transition to hypertrophic chondrocytes responding to excessive stress. Aberrant endochondral ossification in the articular cartilage, such as chondrocyte proliferation, differentiation and apoptosis, are thought to play an important role in the development of osteoarthritis. The research about molecular mechanisms controlling the endochondral ossification in the growth plate of bone thus can give us an important clue to understand the pathogenesis of osteoarthritis. Several lines of evidences suggest that the stromal cell-derived factor-1 alpha (SDF-1a) has been implicated in osteoarthritis, but their exact mechanisms still remains unclear. In this study, we investigated the roles of SDF-1a on the endochondral ossification. Methods: Primary chondrocytes and tibial explants from embryonic 15.5 day-oldmicewereculturedwithPBSvehicleor recombinantmouseSDF-1a. Total RNA was isolated from primary cell cultures using a Qiagen RNeasy Mini Kit. Real-time PCR analysis was performed using Applied Biosystems 7900 HT Real-Time PCR System and TaqMan Gene Expression Assays for Sox9, Col2a1, Acan, MMP13, Col10a1, Runx2. Organ culture tissues were stained with safranin O/fast green and alcian blue/alizarin red, and the immunohistochemistry was also performed on tissue sections with antiCaspase3, anti-MMP13, anti-Runx2, anti-COL10, anti-proliferating chondrocyte nuclear antigen (PCNA) and anti-SOX9 antibodies Results:Primarychondrocyte cultures revealed that SDF-1a significantly increased the expression of aggrecan and Col10a1 which is a marker for chondrocyte proliferation and hypertrophy, respectively (p<0.05). The master regulator gene of chondrocyte hypertrophy, Runx2, was also upregulated in messenger RNA level by SDF-1a (p<0.05). To gain further insights into the role of SDF-1a on endochondral ossification, we examined the effects of SDF-1a in tibia organ cultures. The length of tibias, comparedwith the controls, was significantly increased in SDF-1a treatment group (p<0.05). Immunohistochemical staining of organ cultures agreed with the morphologic finding; the expression of PCNA, themarker for chondrocyteproliferationandSox9markedly increased in chondrocytes of proliferating zone. In addition to proliferation marker, type 10 collagen, the marker for hypertrophy and Caspase3, were upregulated in hypertrophic zone by SDF-1a. Conclusions: Our findings reveal that SDF-1a has an effect on chondrocyte proliferation, hypertrophy and apoptosis during endochondral ossification through Sox9 and Runx2. SDF-1a thus may represent a therapeutic target of osteoarthritis. 72 NG2/CSPG4 REGULATES AGGRECANASE AND MMP EXPRESSION IN HUMAN CHONDROCYTES N.S. Jamil, A. Azfer, H.E. Sarah, D.M. Salter. Univ. of Edinburgh, Edinburgh,