Effect Of Compression Stress On The Expression Of Integrin Alpha5Beta1 In Goat TMJ Disc Fibrochondrocytes In Self-assembled Engineered Constructs

Objective:The purpose of this study was to investigate the expression of integrin alpha5betal in native goat temporomandibular joint disc (TMJ disc) tissue and its fibrochondrocytes cultured in vitro and to determine the effect of compression stress on the expression of integrin alpha5betal in TMJ disc fibrochondrocytes from self-assembled engineered constructs.Methods:1. Expression of integrin alpha5betal in native one-month-aged goat TMJ disc was examined by immunohistochemistry. TMJ disc fibrochondrocytes were isolated from one-month-aged goat TMJ discs with 0.1% type I collagenase and passaged to P3 for the immunohistochemical staining of integrin alpha5betal of in vitro TMJ disc fibrochondrocytes.2. TMJ disc fibrochondrocytes were passaged to P3 for forming tissue engineered constructs.2×106 cells were seeded into 5 mm,2% agarose-coated wells to form self-assembled constructs and then at week 2 those constructs were randomly divided into three loading groups:non-loaded control, dynamic compression stress at 0-0.2 MPa,1 Hz,2 h/d and constant compression stress at 0.2 MPa,2 h/d.1 week later, general morphological and histological data of constructs were taken and IHC staining for integrin alpha5betal in constructs was quantified using an image analysing system (Image-Pro Plus 6.0(Media Cybernetics, Sliver Spring, MD, US)).Results:1. Both fibroblast-like and chondrocyte-like cells in native goat TMJ disc were stained positive for integrin alpha5betal. Integrin alpha5betal was mainly located in the cell membrane and cytoplasm according to the IHC of the cultured TMJ disc fibrochondrocytes.2. The self-assembled constructs of the three loading groups at week 3 were not shown morphologically different, although picrosirius red staining for collagen staining of dynamic compression stress group was more obvious than that of constant compression stress and non-loaded control group. IHC staining for integrin alpha5betal was globally uniformly distributed; dynamic compression stress group was more intensely and uniformly stained with a significantly higher optical density (OD value) than that found in constant compression stress and non-loaded control group and constant compression stress group had an insignificantly lower OD value than non-loaded control group.Conclusion:1. Integrin alpha5betal is expressed by TMJ disc native tissue and its fibrochondrocytes.2. Dynamic compression stress other than constant compression stress could upregulate the expression of integrin alpha5betal in goat TMJ disc self-assembled constructs, which suggests that integrin alpha5betal may be involved in the mechanotransduction of goat TMJ disc fibrochondrocytes from self-assembled constructs under compression stress.