Liu Fei, Wang Zhifeng, Liu Fangfang, Xu Jinzhao, Liu Qibo, Yin Kaifeng, Lan Jing
1Department of Prosthodontics, School of Stomatology, Shandong University, Jinan, 250000 China.
Shandong Provincial Key Laboratory of Oral Tissue Regeneration, 44-1 West Wenhua Street, Jinan, 250012 Shandong China.
Cell Biosci. 2018 Oct 26;8:55. doi: 10.1186/s13578-018-0254-y. eCollection 2018.
Fine osseointegration is the basis of long-term survival of implant. In our previous study, we observed a strong correlation between hyperlipidemia and compromised osseointegration. MicroRNA-29a-3p (miR-29a-3p) has been discovered to participate in bone marrow mesenchymal stem cells (BMSCs) differentiation. However, the role and the underlying mechanisms of hyperlipidemia and miR-29a-3p in osseointegration still remain obscure.
In peri-implant bone tissues of hyperlipidemia rats, bone mass, mineralization and bone trabecula formation were weakened. Alkaline phosphatase (ALP) and runt-related transcription factor 2 (Runx2), and miR-29a-3p expression were reduced. While in normal rats, implant-bone interfaces were filled with dense new bone and ALP, Runx2 and miR-29a-3p were up-regulated. Overexpressed miR-29a-3p can reverse the adverse effect of hyperlipidemia on osseointegration. Implants were tightly integrated with the surrounding dense new bone tissues, and ALP as well as Runx2 mRNAs were enhanced in miR-29a-3p overexpressed and hyperlipidemia rats, while little peri-implant bone tissue existed, ALP and Runx2 deregulated on miR-29a-3p inhibited rats. Dishevelled 2 (Dvl2) mRNA was declined in peri-implant bone tissue of high-fat (HF) group than normal group, while frizzled 4 (Fzd4) mRNA declined on day 5 and increased from day 10 to day 20 after implantation in hyperlipidemia rats than in normal rats. Next, BMSCs were cultured under HF or normal medium in vitro. In the HF group, ALP activity and mineralization, ALP and Runx2 mRNAs and proteins expression, and miR-29a-3p expression were suppressed, while adipogenesis was increased, as a result, cytoskeletons were sparse and disordered compared to control group. However, when miR-29a-3p was overexpressed in BMSCs, ALP activity, ALP, Runx2, Dvl2 and Fzd4 mRNAs and proteins expressions were up-regulated. As miR-29a-3p was inhibited in BMSCs, the reverse results were obtained. In addition, promoter assay revealed that miR-29a-3p can directly suppress Wnt/β-catenin pathway related Dvl2 and Fzd4 through binding to their 3'-UTR.
MiR-29a-3p facilitated implant osseointegration via targeting Wnt/β-catenin pathway-related Dvl2 and Fzd4. MiR-29a-3p/Dvl2/Fzd4 may serve as a promising therapeutic target for hyperlipidemia osseointegration.
良好的骨整合是种植体长期存活的基础。在我们之前的研究中，我们观察到高脂血症与骨整合受损之间存在密切关联。已发现微小RNA - 29a - 3p（miR - 29a - 3p）参与骨髓间充质干细胞（BMSCs）的分化。然而，高脂血症和miR - 29a - 3p在骨整合中的作用及潜在机制仍不清楚。
在高脂血症大鼠的种植体周围骨组织中，骨量、矿化和骨小梁形成减弱。碱性磷酸酶（ALP）、 runt相关转录因子2（Runx2）和miR - 29a - 3p表达降低。而在正常大鼠中，种植体 - 骨界面充满致密的新骨，ALP、Runx2和miR - 29a - 3p上调。过表达miR - 29a - 3p可逆转高脂血症对骨整合的不利影响。种植体与周围致密的新骨组织紧密整合，在过表达miR - 29a - 3p的高脂血症大鼠中，ALP以及Runx2 mRNA增强，而在抑制miR - 29a - 3p的大鼠中，种植体周围骨组织很少，ALP和Runx2失调。与正常组相比，高脂（HF）组种植体周围骨组织中Dishevelled 2（Dvl2）mRNA下降，而在高脂血症大鼠中，植入后第5天卷曲蛋白4（Fzd4）mRNA下降，从第10天到第20天增加。接下来，在体外HF或正常培养基中培养BMSCs。在HF组中，ALP活性和矿化、ALP和Runx2 mRNA及蛋白表达以及miR - 29a - 3p表达受到抑制，但脂肪生成增加，结果与对照组相比，细胞骨架稀疏且紊乱。然而，当miR - 29a - 3p在BMSCs中过表达时，ALP活性、ALP、Runx2、Dvl2和Fzd4 mRNA及蛋白表达上调。当miR - 29a - 3p在BMSCs中被抑制时，得到相反的结果。此外，启动子分析表明，miR - 29a - 3p可通过结合其3'-UTR直接抑制Wnt/β-连环蛋白途径相关的Dvl2和Fzd4。
MiR - 29a - 3p通过靶向Wnt/β-连环蛋白途径相关的Dvl2和Fzd4促进种植体骨整合。MiR - 29a - 3p/Dvl2/Fzd4可能是高脂血症骨整合的一个有前景的治疗靶点。
