Study on adenovirua vector-mediated gene therapy as a therapeuticc approach for bone diseases

破骨细胞是骨吸收的主要细胞，在骨质疏松、类风湿关节炎、转移性骨肿瘤等病理性骨吸收以及正常骨建模和重塑中发挥重要作用。因此，揭示破骨细胞骨吸收的分子机制将引导我们建立一种新的治疗方法。为了研究一个分子在细胞中的功能，基因转导被广泛使用并且非常有用。然而，由于破骨细胞是终末分化的非增殖细胞，基因转导到破骨细胞是非常困难的。在这个项目中，我们证明了腺病毒载体可以有效地转导破骨细胞（Tanaka et al., 1998）。对敲除小鼠的研究表明，非受体型酪氨酸激酶c-Src在破骨细胞骨吸收中起重要作用。我们构建了一种携带csk基因的腺病毒载体（csk病毒），可以负向调节c-Src的活性。Csk病毒能有效地将Csk基因转导成破骨细胞，并强烈抑制细胞的骨吸收活性。我们进一步研究了病毒在体内的作用。在小鼠颅骨骨膜上注射csk病毒可明显抑制IL-1诱导的骨吸收。关节内注射病毒也减少了佐剂性关节炎大鼠的骨破坏。这些结果表明，csk病毒是一种治疗病理性骨破坏的良好手段。我们将能够利用我们建立的方法阐明破骨细胞骨吸收的分子机制。

Osteoclasts are primary cells responsible for bone resorption, and the cells play important roles in pathological bone resorption such as osteoporosis, rheumatoid arthritis and metastatic bone tumors as well as normal bone modeling and remodeling. Therefore, revealing the molecular mechanism of osteoclastic bone resorption leads us to establish a novel therapeutic approaches for these disorders. To investigate the function of a molecule in the cells, gene transduction is widely utilized and quite useful. However, because osteoclasts are terminally differentiated non proliferating cells, gene transduction into osteoclasts are extremely difficult. In this project, we demonstrated that adenovirus vectors can efficiently transduce osteoclasts (Tanaka et al., 1998).The study on the knock-out mice revealed that a non-receptor-type tyrosine kinase, c-Src plays an essential role for osteoclastic bone resorption. We constructed an adenovirus vector carrying csk gene (csk virus), which negatively regulate c-Src activity. Csk virus can efficiently transduce csk gene into osteoclasts, and strongly suppressed bone-resorbing activity of the cells. We further examined the effect of the virus in vivo. Injection of csk virus on the periosteum of mouse calvaria significantly inhibited the bone resorption induced by IL-1 administration. Intraarticular injection of the virus also reduced the bone destruction in adjuvant arthritis rats. These results showed that csk virus can be a good therapeutic means of pathological bone destruction. We will be able to elucidate the molecular mechanism of osteoclastic bone resorption using the method we established.