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. Transforming growth factor-beta (TGF-β), a cytokine superfamily, regulates cell function, including differentiation and proliferation. Although the function of the TGFβs in various cell types has been investigated, their function in cartilage repair is as yet not fully understood. The effect of TGF-β3 in biological regulation of primary chondrocyte was investigated in this work. TGF-β3 provide fibroblastic morphology to chondrocytes and therefore overall reduction in cell proliferation was observed. The length of the cells supplemented with TGF-β3 were larger than the cells without TGF-β3 treatment. This was caused by the fibroblast like cells (dedifferentiated chondrocytes) which occupied larger areas compared to cells without TGF-β3 addition. The healing process of the model wound closure assay of chondrocyte multilayer was slowed down by TGF-β3, and this cytokine negatively affected the strength of chondrocyte adhesion to the cell culture surface.

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Cytokines are extremely potent biomolecules that regulate cellular functions and play multiple roles in initiation and inhibition of disease. These highly specialised macromolecules are actively involved in control of cellular proliferation, apoptosis, cell migration and adhesion. This work, investigates the effect of transforming growth factor-beta2 (TGF-β2) on the biological regulation of chondrocyte and the repair of a created model wound on a multilayer culture system. Also the effect of this cytokine on cell length, proliferation, and cell adhesion has been investigated. Chondrocytes isolated from knee joint of rats and cultured at 4 layers. Each layer consisted of 2 × 105 cells/ml with and without TGF-β2. The expression of mRNA and protein levels of TGF-β receptors and Smad1, 3, 4, and 7 have been analysed by RT-PCR and western blot analysis. The effect of different supplementations in chondrocyte cell proliferation, cell length, adhesion, and wound repair was statistically analysed by One-way ANOVA test. Our results showed that the TGFβ2 regulates mRNA levels of its own receptors, and of Smad3 and Smad7. Also the TGF-β2 caused an increase in chondrocyte cell length, but decreased its proliferation rate and the wound healing process. TGF-β2 also decreased cell adhesion ability to the surface of the culture flask. Since, TGF-β2 increased the cell size, but showed negative effect on cell proliferation and adhesion of CHC, the effect of manipulated TGF-β2 with other growth factors and/or proteins needs to be investigated to finalize the utilization of this growth factor and design of scaffolding in treatment of different types of arthritis.

The effect of transforming growth factors-β (TGF-βs) in the regulation and control of cell growth is widely studied, but the capability of these cytokines to regulate chondrocyte cell functions such as migration, cell death, proliferation, differentiation and wound repair is not clearly understood. In this work the effect of TGF-β1 on the biological regulation of chondrocyte was evaluated using a model wound closure assay. The experiments were carried out on primary chondrocyte cells with fibroblast like and chondrocytic phenotypes. The cells were isolated from knee articular cartilage of five day old Sprague-Dawley neonate rats and seeded at low density to obtain a fibroblast like morphology. Chondrocytes with chondrocytic phenotype were derived by seeding at high density.The results revealed that TGF-β1 slowed down proliferation and migration of cells into a model wound. It was also found that cell attachment, as determined by the detachment time during trypsinization, was greater for cells with a fibroblast like morphology when compared with cells exhibiting chondrocytic morphology. Treatment with TGF-β1 was found to increase the detachment times of fibroblast like chondrocytes, indicating that TGF-β1enhanced cell attachment of this cell type, whilst treatment with TGF-β1 decreased detachment time for the chondrocytic type chondrocyte cells indicating that TGF-β1 decreased cell attachment in these cells.

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