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

骨髓中含有大量间充质干细胞（MSCs），它们具有分化成骨、软骨、脂肪和其他组织通路的潜力。来自不同物种的间充质干细胞已经被研究过，它们都表现出一些特定的特征。尽管犬类实验模型被广泛用于体内和体外实验，但有关犬类间充质干细胞的信息有限。要使间充质干细胞发生软骨分化，支持细胞间强相互作用的因子（颗粒培养系统）、生长因子（转化生长因子β）和维持球形形态的环境（聚合物和II型胶原凝胶）被认为是必要的。因此，本研究的主要目的是在干细胞研究中引入新的动物实验模型，并利用该模型来了解分化因子对MSC软骨分化的影响。本研究的一半以上结果表明：1)骨软糖基质细胞具有广泛增殖和多系分化的潜力，可称为MSCs；ii)在颗粒培养系统中培养的MSCs在没有任何外部添加生物活性刺激物的情况下表现出自发成软骨分化的特定物种特征；iii) II型胶原，它是关节软骨的生理成分，具有诱导和维持的潜力，事先与tgf - β相互作用可显著增加MSC软骨形成。这些结果将有助于建立新的干细胞研究动物模型，了解生长因子、培养系统和ECM对间充质干细胞成软骨的影响，并最终证明牛间充质干细胞可能在独特的机制下发生成软骨分化。本研究的后半部分是为了研究关节炎状态下MSCs应用的关节间隙环境。这里我们集中展示了滑膜和软骨细胞对外源性透明质酸的反应。本部分研究表明：1)犬CD44基因在体外滑膜细胞和软骨细胞中均有表达；ii)犬透明质酸合成酶（HAS）基因在体外滑膜细胞和软骨细胞中均有表达；iii)研究实验性炎症条件下体外HAS基因的不同表达。本部分研究结果提示，外源性透明质酸诱导犬滑膜细胞和软骨细胞的ha -2基因活化，从而合成高分子量的透明质酸，这可能解释了透明质酸对炎症的抑制作用。少

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