可注射纳米复合甲基丙烯酸化明胶水凝胶在骨修复中的应用

目的 构建可缓释血小板衍生生长因子（PDGF）的可注射复合成骨水凝胶，验证其体内外成骨再生效应。方法 通过简单共混纳米锂钙石（SN）、PDGF与甲基丙烯酸化明胶（GelMA），构建可注射复合水凝胶（GelMA-SN-PDGF），并进一步通过紫外光交联优化水凝胶力学性能。扫描电子显微镜、流变仪、万能力学试验机等分析GelMA-SN-PDGF的理化属性和力学性能；ELISA法测定复合水凝胶的PDGF缓释曲线，Transwell和划痕实验验证复合水凝胶的趋化性能；CCK-8法、Live/Dead染色法、DAPI-Phalloidin染色法评估GelMA-SN-PDGF的生物相容性；qRT-PCR和免疫荧光染色标记法评估GelMA-SN-PDGF的体外成骨能力，茜素红染色法分析其基质矿化能力。建立大鼠颅骨临界骨缺损模型并通过Micro-CT和Masson三色染色分析GelMA-SN-PDGF的体内成骨能力。结果 GelMA-SN-PDGF复合水凝胶制备简易，能通过注射器注射，SN和PDGF的加入并未显著影响GelMA支架结构，紫外光交联后的GelMA支架满足骨髓间充质干细胞（BMSCs）成骨分化的力学环境；PDGF在复合水凝胶中实现了理想的长期控释模式，并有效地刺激了BMSCs的归巢。GelMA-SN-PDGF复合水凝胶在体外促进了BMSCs中成骨相关标志物的表达和基质矿化，并展现了较好的体内临界骨缺损修复能力。结论 可注射的GelMA-SN-PDGF复合水凝胶具有良好的生物相容性和生物活性，能通过注射器微创修复骨缺损，体内外成骨效应较好，为临床骨缺损治疗提供了一种简单而快速的策略。

Injectable Nanocomposite Methacrylated Gelatin Hydrogel for Bone Defects Repairing

Objective To construct an injectable composite osteogenic hydrogel capable of controlled releasing platelet-derived growth factor (PDGF) and verify its bone regeneration effect in vivo and in vitro. Methods The injectable nanocomposite hydrogel (GelMA-SN-PDGF) was constructed via simply mixing nano-silicate (SN), PDGF and methacrylated gelatin (GelMA), and its mechanical properties was optimized by further UV crosslink. Physical and chemical characteristics as well as mechanical properties of GelMA-SN-PDGF were analyzed by electron microscope, rheometer, universal testing machine, Fourier infrared spectrometer. The releasing curve of PDGF from the hydrogel was profiled by ELISA, and the chemotactic capacity by Transwell and Scratch tests. CCK-8, Live/Dead assay, and DAPI-Phalloidin staining were used for the biocompatibility of GelMA-SN-PDGF, qRT-PCR and immunofluorescence labeling for the quantitative evaluation of the osteogenic biomarkers of GelMA-SN-PDGF, and the Alizarin Red staining for the matrix mineralization. Osteogenic ability in vivo of GelMA-SN-PDGF was evaluated by Micro-CT and Masson''s trichrome staining in the critical cranial defects in rats. Results GelMA-SN-PDGF composite hydrogel could be simply constructed and passed through a syringe. SN and PDGF in the hydrogel hardly affected the GelMA scaffolds. Hydrogel after UV crosslink satisfied the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). GelMA-SN-PDGF hydrogel promoted the expression of osteogenic biomarkers in BMSCs and matrix mineralization in vitro, and exhibited a superior ability to repair critical cranial defects in vivo. Conclusion The injectable GelMA-SN-PDGF hydrogel owns good biocompatibility and bioactivity, repairing bone defects via minimally invasive way after simply constructed, showing superior osteogenesis effects in vivo and in vitro, and provides a simple and fast strategy for clinical bone defect treatment.