Role and Potential of Tissue Mesenchymal Stem cells on joint cartilage repair in dogs

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The bone marrow harbors a population of mesenchymal stem cells (MSCs) that possess the potential to differentiate into bone, cartilage, fat and along other tissue pathways. MSCs from various species have been studied, and all of them demonstrated some specific characteristics. Despite the canine experimental model being widely used in experiments in vivo and in vitro, only a limited amount of information regarding canine MSCs is available. MSCs to undergo chondrogenic differentiation, factors that support strong cell to cell interaction (pellet culture system), growth factors (transforming growth factor beta), and an environment that maintains spherical morphology (polymer and collagen typew II gels) are considered to be necessary. For this reasons the main objective of this study was to introduce new animal experimental models in stem cell research and by using this model to contribute in understanding the influence of differentiate factors on MSC chondrogenic differentiation.The firs … More t half of this study showed that: i) cells from bone mallow stroma have potential for extensive proliferation and multilineage differentiation, refereeing them as MSCs; ii) MSCs cultured in pellet culture system demonstrated specific species character to undergo spontaneous chondrogenic differentiation without any external added bioactive stimulators; iii) collagen type II, which is physiological component of articular cartilage has potential to induce and maintain, and prior interation with TGF-betal dramatically to increase MSC chondrogenesis. These results would contribute for establishing new animal model for stem cell research, in understanding of growth factors, cluture system and ECM influence on MSC chondrogenesis, and finally in demonstration that bovine MSCs undergo chondrogenic differentiation probably under unique mechanism.The second half of this research was done for investigating environment of joint space under arthritic condition for MSCs to be applied. Here we concentrated to show synovial and chondrocytic reaction to exogenous hyaluronic acid. This pat of our study showed that: I) the expression of canine CD44 gene was demonstrated in both synovial cells and chondrocytes in vitro.; ii) the expression of canine hyaluronic acid synthase (HAS) genes was demonstrated in both synovial cells and chondrocytes in vitro; and iii) different expression of HAS genes in vitro under experimental inflammatory conditions was investigated. The results from this part of study suggested that exogenous hyaluronic acid induced activation of canine HAS-2 gene in canine synovial cells and chondrocytes, leading to the synthesis of high molecular weight hyaluronic acid, might explain inhibitory effects of hyaluronic acid on inflammation. Less