基于BMP/Smad信号通路探讨贝尼地平缓释微球促进骨再生作用及机制研究

Benidipine (BD) is the second generation of dihydropyridine calcium antagonist, which is often used for hypertension and angina pectoris. Previous studies have demonstrated that BD has a positive effect on bone metabolism in addition to its conventional usage, and may be a suitable candidate for the treatment of patients with jaw defect. However, the mechanism of BD on promoting osteogenesis is not clear. The short half-life, low bioavailability and the side effect of lowering blood pressure all limit the clinical application of BD for bone regeneration. Inspired by this promoting phenomenon as well as disadvantages, we will use magnesium silicate nanospheres (MSNs) as a drug carrier, which possess both osteogenic capacity and sustained-release property, to synthesise benidipine-loaded magnesium silicate nanospheres (BD-MSNs). In vitro, we will investigate the effects of BD-MSNs on osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and study the mechanism of BD-MSNs on promoting osteogenesis based on BMP/Smad signal pathway via Real-time PCR, Western blot, siRNA and etc. In vivo, we would set up the rat cranial defect model and administrate the BD-MSNs locally, then Micro CT, immunohistochemistry methods are used to test the effect of BD-MSNs on the regeneration of bone defect. The preparation of BD-MSNs drug delivery system will improve the stability, enhance the bioavailability and reduce the side effect of BD, so as to establish a theoretical basis for the further clinical application of BD in bone tissue engineering. In the meanwhile, this study could also provide a new method for the treatment of the absorption and defect of jaw bone.

贝尼地平（benidipine，BD）是临床常用的降压药物，近期研究发现BD还具有促进骨质生成的作用，推测可将其作为颌骨再生修复的功能药物。然而BD促进成骨的作用机制尚不明确，生物利用度低、过量应用致使血压过低等问题限制了BD促进骨再生作用的临床应用。本课题以提高BD生物利用度并探讨其促骨再生的作用机制为目的，采用兼具缓释特性及促成骨分化作用的硅酸镁微球作为载体，制备载BD药物的缓释微球，并建立与大鼠骨髓间充质干细胞共培养体系，采用实时定量PCR、Western blot及siRNA等技术方法探究该缓释微球促成骨分化作用及通过BMP/Smad信号通路调控成骨分化的机制。同时建立大鼠颅骨缺损模型并局部应用缓释微球，通过Micro CT和免疫组化等技术从体内水平探索该缓释体系修复骨缺损的作用效果。本课题将为BD促骨再生作用的临床应用奠定理论基础，也将为颌骨缺损的再生修复提供新的药物治疗思路。

贝尼地平（benidipine，BD）是临床常用的降压药物，近期研究发现BD具有促进骨质生成的作用，推测可将其作为颌骨再生修复的功能药物。然而BD促进成骨作用机制尚不明确，生物利用度低、过量应用致使血压过低等问题限制了BD促进骨再生作用的临床应用。本研究通过制备载BD药物的缓释微球，并通过体内、体外实验探讨该载药缓释体系促进成骨作用的效果及机制。首先本研究成功制备贝尼地平缓释微球（BD-MSNs），观测载药微球形态结构，计算微球的载药率，检测药物释放特性。结合各项参数筛选出载药量适宜且缓释作用持久的微球用于后续实验。其次，建立了Wistar大鼠骨髓间充质干细胞（BMSCs）与BD-MSNs共培养体系，检测结果显示载药缓释微球能够促进BMSCs的增殖、分化及矿化能力，并上调作用后细胞成骨分化相关基因和蛋白的表达。采用BMP拮抗剂检测信号关键蛋白磷酸化水平的变化，结果表明BD-MSNs可能通过BMP/Smad信号通路调节成骨向分化的作用机制。最后建立Wistar大鼠颅骨缺损模型并局部应用BD-MSNs，观测颅骨缺损处骨修复情况，明确了BD-MSNs于体内促进成骨的作用效果。本课题将为BD促骨再生作用的临床应用奠定理论基础，也将为颌骨缺损的再生修复提供新的药物治疗思路。.