Cell and tissue engineering of articular cartilage via regulation and alignment of primary chondrocyte using manipulated transforming growth factors and ECM proteins. Effect of transforming growth factor-beta (TGF-¿1, 2 and 3) on the biological regulation and wound repair of chondrocyte monolayers with and without presence of ECM proteins.

Abstract

Articular cartilage is an avascular and flexible connective tissue found in joints. It produces a cushioning effect at the joints and provides low friction to protect the ends of the bones from wear and tear/damage. It has poor repair capacity and any injury can result pain and loss of mobility. One of the common forms of articular cartilage disease which has a huge impact on patient¿s life is arthritis. Research on cartilage cell/tissue engineering will help patients to improve their physical activity by replacing or treating the diseased/damaged cartilage tissue. Cartilage cell, called chondrocyte is embedded in the matrix (Lacunae) and has round shape in vivo. The in vitro monolayer culture of primary chondrocyte causes morphological change characterized as dedifferentiation. Transforming growth factor-beta (TGF-¿), a cytokine superfamily, regulates cell function, including differentiation and proliferation. The effect of TGF-¿1, 2, 3, and their manipulated forms in biological regulation of primary chondrocyte was investigated in this work. A novel method was developed to isolate and purify the primary chondrocytes from knee joint of neonate Sprague-Dawley rat, and the effect of some supplementations such as hyaluronic acid and antibiotics were also investigated to provide the most appropriate condition for in vitro culture of chondrocyte cells. Addition of 0.1mg/ml hyaluronic acid in chondrocyte culture media resulted an increase in primary chondrocyte proliferation and helped the cells to maintain chondrocytic morphology. TGF-¿1, 2 and 3 caused chondrocytes to obtain fibroblastic phenotype, alongside an increase in apoptosis. The healing process of the wound closure assay of chondrocyte monolayers were slowed down by all three isoforms of TGF-¿. All three types of TGF-¿ negatively affected the strength of chondrocyte adhesion. TGF-¿1, 2 and 3 up regulated the expression of collagen type-II, but decreased synthesis of collagen type-I, Chondroitin sulfate glycoprotein, and laminin. They did not show any significant change in production of S-100 protein and fibronectin. TGF-¿2, and 3 did not change expression of integrin-¿1 (CD29), but TGF-¿1 decreased the secretion of this adhesion protein. Manipulated TGF-¿ showed huge impact on formation of fibroblast like morphology of chondrocytes with chondrocytic phenotype. These isoforms also decreased the expression of laminin, chondroitin sulfate glycoprotein, and collagen type-I, but they increased production of collagen type-II and did not induce synthesis of fibronectin and S-100 protein. In addition, the strength of cell adhesion on solid surface was reduced by manipulated TGF-¿. Only manipulated form of TGF-¿1 and 2 could increase the proliferation rate. Manipulation of TGF-¿ did not up regulate the expression of integrin-¿1in planar culture system. The implications of this R&D work are that the manipulation of TGF-¿ by combination of TGF-¿1, 2, and 3 can be utilized in production of superficial zone of cartilage and perichondrium. The collagen, fibronectin and hyaluronic acid could be recruited for the fabrication of a biodegradable scaffold that promotes chondrocyte growth for autologous chondrocyte implantation or for formation of cartilage.