骨内靶向表达rAAV-BMP-2/-OA治疗激素性骨质疏松症的实验研究

The main reason of osteopenia in glucocorticoid-induced osteoporosis is lipoblasts increase at the cost of decreasing osteogenesis induced by glucocorticoid. It is considered one of the mechanisms of glucocorticoid-induced osteoporosis is probably BMP-2 down-regulates expression of OA by Smad1 signal pathway which leads to osteogenesis inhibition and adipogenesis promotion of bone marrow stem cells. In this research, we planned to construct tetracycline up-regulated Tet-on gene expression system and make use of its regulate factor－vibramycin to compose bone matrix-vibramycin slow-release system which could facilitate targeted activation of Tet-on gene expression system injected and expression of AAV-rtTA2s-S2-TRE- BMP-2/OA via adenoassociated virus .In this way, BMP-2 positive regulation pathway was activated for osteoporosis therapy. In order to explore molecular mechanism of BMP-2/OA regulation at transcription level toward differentiation to osteogenesis and adipogenesis ,we focused on the effect of upregulated expression of BMP-2/OA on key transcript factors and gene specific expression in the above differentiation process, which could also provide theoretical support for treating glucocorticoid-induced osteoporosis as well as other osteopenia diseases.

激素性骨质疏松中,激素导致的以牺牲成骨为代价的脂肪细胞增多是骨量减少的重要原因之一。研究发现，糖皮质激素所致的骨质疏松的机理之一可能是BMP-2通过Smad1信号下调骨活素表达从而抑制BMSC成骨分化、促进成脂分化来实现的。本课题拟构建四环素正向调节的Tet-on基因表达系统，利用其调控因子强力霉素的亲骨特性,组成骨基质－强力霉素缓释系统，从而使注射入体内的Tet-on基因表达系统在骨组织中靶向启动和表达腺相关病毒介导的AAV-rtTA2s-S2-TRE- BMP-2/OA，从而激活BMP-2的正向调节通路治疗骨质疏松。研究BMP-2/OA表达上调后对激素诱导下BMSCs成骨－成脂分化过程中关键转录因子和特异性功能基因的表达的影响，探索BMP-2/OA调控BMSCs成脂、成骨分化转录水平的分子机制，为激素性骨质疏松症及其他骨量丢失疾病的临床治疗提供理论依据。

激素性骨质疏松中,激素导致的以牺牲成骨为代价的脂肪细胞增多是骨量减少的重要原因之一。研究发现,糖皮质激素所致的骨质疏松的机理之一可能是BMP-2的表达抑制导致Smad1信号及骨活素表达水平的下调从而抑制 BMSC 成骨分化、促进成脂分化来实现的。本课题通过构建腺相关病毒介导BMP-2/OA过表达体系,从而激活BMP-2的正向调节通路。进而研究 BMP-2/OA 表达上调后对BMSCs 成骨/成脂分化过程中关键转录因子和特异性功能基因的表达的影响,探索BMP-2/OA 调控 BMSCs 成脂、成骨分化转录水平的分子机制,为激素性骨质疏松症及其他骨量丢失疾病的临床治疗提供理论依据。通过本实验研究结果,初步得出以下结论: .1、证实了糖皮质激素所致的骨质疏松的机理之一是通过下调OA表达从而抑制BMP-2/Smad1信号通路活性来实现的。.2、应用过表达病毒载体上调BMP-2、OA的表达，可调控BMSCs成骨、成脂分化，从而为骨质疏松等与BMSCs细胞脂肪变性有关疾病的基因治疗途径提供实验及理论依据。