流体切应力对成骨细胞Wnt/β-连锁蛋白信号转导通路的影响

背景：力学刺激对Wnt/β-连锁蛋白信号转导通路对成骨细胞的分化,增殖和凋亡有重要作用。Wnt/β-连锁蛋白信号转导通路的影响是近年来研究的热点。 目的：探讨流体切应力对Wnt/β-连锁蛋白信号转导通路的影响在促进骨细胞骨形成和修复中的作用。 方法：应用计算机检索CNKI 期刊全文数据库和PubMed数据库(1990-01/2009-12)与流体切应力对成骨细胞Wnt/β-连锁蛋白信号转导通路影响有关的文章,纳入43篇符合标准的文献进行综述。 结果与结论：力学负荷刺激Wnt/β-连锁蛋白信号转导通路可提高LRP5 G171V鼠骨细胞骨形成敏感性,导致骨量增多,密度增大。体内和体外力学实验都支持Wnt/β-连锁蛋白信号转导通路是力学刺激的正常反应通路,Wnt/β-连锁蛋白信号转导通路在力学刺激作用下能提高成骨或骨细胞的成骨敏感性。     

可降解生物材料聚乳酸-羟基乙酸仿生矿化的实验研究

目的：通过对聚乳酸-羟基乙酸共聚物(poly lactide-co-glycolide，PLGA)的仿生矿化，表面改性，以提高其细胞粘附性；探讨影响仿生矿化的因素和条件，为进一步制备组织工程化人工骨提供依据和实验基础。方法：PLGA膜经碱性溶液水解处理后，应用高温显微镜测量材料表面润湿角的变化；碱处理后的PLGA膜和三维多孔PLGA分别在模拟体液(Simulated Body Fluid，SBF)中矿化14d，在1．5倍SBF中矿化9d，应用扫描电镜进行矿化物形貌观察，X射线能谱分析钙磷比值，X射线衍射仪和傅立叶转换红外光谱仪行矿化物物相分析。结果：PLGA经碱性溶液水解处理后表面亲水性明显增强，在SBF及1．5倍SBF中矿化后表面可以形成明显的矿化物；矿化物的形态与矿化液的浓度有关；矿化物主要成分为羟基磷灰石(HA)，含有碳酸根成分，钙磷比为1．53，类似于人骨无机质。结论：PLGA仿生矿化是制备结构及性质类似骨基质人工骨的可行方法。     

仿生骨基质材料的研究进展

骨缺损修复是临床中所面临的难题之一,为了解决这个难题,人们研制了不同的仿生骨基质材料。本文对仿生骨基质材料的研究进展进行综述。     

流体切应力促进组织工程骨成骨和血管化的研究进展

流体切应力在组织工程学中得到越来越多的重视。通过模拟流体切应力作用于骨组织后对感应细胞（成骨细胞和血管内皮细胞）产生刺激,达到骨量增多和快速血管化的目的。通过阐述流体切应力对成骨细胞和血管内皮细胞的作用机制,为促进组织工程骨的成骨和血管化提供思路和依据。     

仿生骨基质材料的研究进展

骨缺损修复是临床中所面临的难题之一，为了解决这个难题，人们研制了不同的仿生骨基质材料。本对仿生骨基质材料的研究进展进行综述。     

新短肽P17-骨形态发生蛋白2/胶原基质矿化磷灰石材料生物活性的评价

文题释义：胶原基质矿化磷灰石：具有良好的生物相容性,不产生排斥反应,降解速度与成骨的速度相适应,其降解不会影响周围环境的pH值。该材料在微米尺度上具有互联孔洞结构,孔隙尺寸为100-500 µm,孔隙率为70%-90%,结构和成分与自体骨相似,能够更好的诱导自体骨生长,具有良好的骨修复作用,其机械耐受性、可塑性、强度接近松质骨。 新短肽P17-骨形态发生蛋白2：通过FMOC/tBu固相多肽合成法合成的具有17个氨基酸的新型活性短肽中包含磷酸化的丝氨酸及天冬氨酸,能够极好地模拟天然骨基质的促发及指导矿化的功能,在局部形成偏酸环境,促进局部的钙磷沉积、成核和生物自组装矿化。短链多肽活性位点能充分暴露并与细胞表面受体结合,生物活性更强。 背景：胶原基质矿化磷灰石材料具有仿生的化学组成及良好的生物学性能,已被用于某些骨缺损修复;新短肽P17-骨形态发生蛋白2具有良好的生物相容性和成骨诱导生物活性,因此将新短肽P17-骨形态发生蛋白2与胶原基质矿化磷灰石材料制备成复合支架材料可望提升骨修复效率和效果。 目的：探讨新型P17-骨形态发生蛋白2/胶原基质矿化磷灰石复合材料的生物活性。 方法：将兔骨髓间充质干细胞分别接种于新型P17-骨形态发生蛋白2/胶原基质矿化磷灰石复合材料与胶原基质矿化磷灰石材料上,培养3,7 d后,利用RT-PCR检测细胞碱性磷酸酶 mRNA相对表达。将新型P17-骨形态发生蛋白2/胶原基质矿化磷灰石复合材料(实验组)与胶原基质矿化磷灰石材料(对照组)分别埋置于SD大鼠皮下,植入12,35 d后进行Masson染色后组织学分析。将新型P17-骨形态发生蛋白2/胶原基质矿化磷灰石复合材料(实验组)与胶原基质矿化磷灰石材料(对照组)分别植入日本大耳白兔下颌骨箱状缺损处,植入5,15周后进行大体与X射线检查。实验经中国医科大学附属口腔医院伦理委员会批准。 结果与结论：①复合材料组培养7 d的碱性磷酸酶mRNA表达高于胶原基质矿化磷灰石组(P < 0.05);②皮下埋植实验显示两组材料和组织界面均未引起明显的急性炎症反应,植入后35 d实验组可见更多的纤维细胞与材料嵌合;③骨缺损修复实验中,大体观察显示两种材料均具有良好的骨修复能力,植入5周时缺损区已有缩小趋势,植入15周缺损表面比较平整;X射线检查显示与对照组相比,实验组缺损区缩小趋势更明显;④结果表明,新型P17-骨形态发生蛋白2/胶原基质矿化磷灰石复合支架材料具有比胶原基质矿化磷灰石更为优良的生物活性与骨缺损修复能力。 ORCID: 0000-0002-1196-5954(张雪) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

骨基质明胶/煅烧骨基质重组人工骨对骨髓间充质干细胞成骨潜能的影响

背景：前期实验发现单纯骨基质明胶材料与骨髓间充质干细胞复合后具有较好的成骨能力,修复骨缺损效果较好,但单纯骨基质明胶降解速度快,硬度差,不能用来修复承重区域的骨缺损。 目的：观察骨基质明胶/煅烧骨基质重组人工骨与骨髓间充质干细胞复合培养后细胞成骨潜能的变化。 方法：利用骨基质明胶和煅烧骨基质制备重组人工骨,并与大鼠骨髓间充质干细胞复合培养48 h,用茜素红染色检测复合培养后细胞的成骨潜能。 结果与结论：细胞在复合材料上能够很好的黏附、生长以及增殖,与重组人工骨复合培养后,细胞的成骨潜能和细胞表型无明显变化。表明重组人工骨易于与骨髓间充质干细胞结合,对细胞成骨潜能无影响,生物相容性良好。     

骨的疲劳损伤和修复

骨是人体承担力学功能的器官，习惯性生理运动范围内中等应力／应变水平就能引起骨的疲劳损伤，激烈运动甚至引起骨折。骨疲劳损伤的实质是骨基质上产生比典型裂纹更小的裂纹，此种裂纹也可能出现在胶原和羟基磷灰石晶体水平，但骨能对基质损伤进行修复，即对损伤区的骨质吸收，然后替换新骨质，骨细胞通过损伤的细胞突和调整性细胞死亡发出骨损伤基质吸收的信号骨细胞在骨基质损伤修复过程中起重要的作用。骨的疲劳和修复是骨的一种生理现象，研究者们把此过程用数学，力学模型定量化描述，以达到对骨生理过程更深的认识及临床实践更好的应用。     

骨缺损仿生支架的研究与思考

<正>大段骨缺损的修复及特定形态骨的功能重建是骨科临床治疗上的一大难题,单纯采用自体骨嫁接或异体骨移植,或采用金属、陶瓷、高分子等各种人工骨替代材料在生物学和力学功能上均难以达到满意的效果。构建有生命活性的,可诱导组织再生的组织工程骨已成为当今修复骨缺损的前沿课题。生物活性诱导材料因采用仿生的理念,通过模拟细胞外基质成     

用磷—钙—胶原复合物模仿长骨单皮质缺损的矿化作用

骨肿瘤、囊肿、畸形所引起的骨缺损常用几种骨修复方式进行纠正:包括冻干骨,填充形态蛋白。生长物及化学性因素的有机物,另外其它高分子的同分异构塑性材料和陶瓷作为骨的代替物。认力生物与趋化性因素是骨感应的材料,而陶瓷和同分异构材料认为起骨传导性的作用。整个材料在某些应用方面及某种程度上显示了骨修复。而本文作者研究设计了确定正常矿化组织的矿化作用是否能作为骨修复     

Synthesis of bone-like nanocomposites using multiphosphorylated peptides

There is a great need for novel materials for mineralized tissue repair and regeneration. Two examples of such tissue, bone and dentin, are highly organized hierarchical nanocomposites in which mineral and organic phases interface at the molecular level. In contrast, current graft materials are either ceramic powders or physical blends of mineral and organic phases with mechanical properties far inferior to those of their target tissues. The objective of this study was to synthesize composite nanofibrils with highly integrated organic/inorganic phases inspired by the mineralized collagen fibrils of bone and dentin. Utilizing our understanding of bone and dentin biomineralization, we have first designed bioinspired peptides containing 3 Ser-Ser-Asp repeat motifs based on the highly phosphorylated protein, dentin phosphophoryn (DPP), found in dentin and alveolar bone. We demonstrate that up to 80% of serines in the peptide can be phosphorylated by casein kinases. We further tested the ability of these peptides to induce biomimetic calcium phosphate mineralization of collagen fibrils. Our mineralization studies have revealed that in the presence of these phosphorylated peptides, mineralized collagen fibrils structurally similar to the mineralized collagen fibrils of bone and dentin were formed. Our results demonstrate that using phosphorylated DPP-inspired peptides, we can successfully synthesize biomimetic composite nanofibrils with integrated organic and inorganic phases. These results provide the first step in the development of biomimetic nanostructured materials for mineralized tissue repair and regeneration using phosphopeptides.     

Dense fibrillar collagen matrices sustain osteoblast phenotype in vitro and promote bone formation in rat calvaria defect

Two pure collagen materials were prepared from acidic collagen solutions at 5 and 40?mg/mL. Benefits of collagen concentration on bone repair were evaluated in vitro with human calvaria cells and in vivo in a rat cranial defect. Both materials exhibited specific structures, 5?mg/mL was soft with an open porous network of fibrils; 40?mg/mL was stiffer with a plugged surface and bundles of collagen fibrils. Osteoblasts seeded on 5?mg/mL formed an epithelioid layer with ultrastructural characteristics of mature osteoblasts and induced mineralization. Numerous osteoblasts migrated inside 5?mg/mL, triggering reorganization of their actin cytoskeleton, whereas on 40?mg/mL osteoblasts remained in a resting state. In rat calvaria defects, both materials induced active bone formation. Dual-energy X-ray absorption bone area measures after 4 weeks averaged 84.0% with 5?mg/mL, 88.4% with 40?mg/mL, and 36.7% in the controls (p?相似文献   

Alignment of osteoblast-like cells and cell-produced collagen matrix induced by nanogrooves

Alignment of bone cells and collagen matrix is closely related to the anisotropic mechanical properties of bone. Intact scaffolds that promote osteoblast differentiation and mineralization in the preferred direction offer promise in the generation of biomimetic bone tissue. In this study, we examined the alignment of osteoblast-like cells and collagen fibers guided by nanogrooves. Nanoscale groove-ridge patterns (approximately 300 nm in periodicity, 60-70 nm in depth) on the surface of polystyrene (PS) were made by polarized Nd:YAG laser irradiation, at a wavelength of 266 nm. The influence of such "nanoscale features" on the orientation and alignment of cells and their mineralized collagen matrix was investigated, using rabbit mesenchymal stem cell (MSC)-derived osteoblast-like cells. The cells and actin stress fibers were aligned and elongated along the direction of the nanogrooves. In addition, the alignment of collagen matrix was also influenced by underlying nanogrooves. The results suggested that nanoscale fibrous cues in the longitudinal direction might contribute to the aligned formation of bone tissue. This may provide an effective approach for constructing biomimetic bone tissue.     

Design of graded biomimetic osteochondral composite scaffolds

With the ultimate goal to generate suitable materials for the repair of osteochondral defects, in this work we aimed at developing composite osteochondral scaffolds organized in different integrated layers, with features which are biomimetic for articular cartilage and subchondral bone and can differentially support formation of such tissues. A biologically inspired mineralization process was first developed to nucleate Mg-doped hydroxyapatite crystals on type I collagen fibers during their self-assembling. The resulting mineral phase was non-stoichiometric and amorphous, resembling chemico-physical features of newly deposited, natural bone matrix. A graded material was then generated, consisting of (i) a lower layer of the developed biomineralized collagen, corresponding to the subchondral bone, (ii) an upper layer of hyaluronic acid-charged collagen, mimicking the cartilaginous region, and (iii) an intermediate layer of the same nature as the biomineralized collagen, but with a lower extent of mineral, resembling the tidemark. The layers were stacked and freeze-dried to obtain an integrated monolithic composite. Culture of the material for 2 weeks after loading with articular chondrocytes yielded cartilaginous tissue formation selectively in the upper layer. Conversely, ectopic implantation in nude mice of the material after loading with bone marrow stromal cells resulted in bone formation which remained confined within the lower layer. In conclusion, we developed a composite material with cues which are biomimetic of an osteochondral tissue and with the capacity to differentially support cartilage and bone tissue generation. The results warrant testing of the material as a substitute for the repair of osteochondral lesions in orthotopic animal models.     

Preparation and Improvation of Nanophase Artificial Bone Composite Scaffold and Relevant Study on Properties

Objective：To prepare nanophase artificial bone composite scaffold based on bionics theory, and probe into how different content ratio between collagen and inorganic part as well as different molecular weight of conglutinant agent influence microstrueture and properties of the scaffold. Methods： Lead calcic inorganic molecules to deposite onto self-assembled collagen template during coprecipitation under certain reactive conditions such as content ratio and pH value of environment, and then nanophase collagen/calcic salt is obtained. In order to improve the mechanical properties, poly lactic acid （PLLA） which has stable equal properties and controllable biodegradable activities is chosen as conglutinant agent, and then the aimed artificial bone scaffold （nanophase collagen/calcic salt/PLLA composite） is accomplished. After preparation liquid displacement method with isoproanol alcohol, scanning electron microscopic （SEM） , transmission electron microscope （TEM）, fourier transform infrared spectrometry （FTIR）, mechanical testing system are performed to test porosity and density, morphology, conformation, composition and mechanical property, respectively. Results：The artificial synthesized bone composite scaffold is mainly composed of collagen and calcium phosphate partly displaced with B-type carbonate. The crystallinity is low, and the crystal size reaches nanometer which is similar to natural bone. PLLA used effectively improves the mechanical property which can reach at the floor level of cancellous standard, and develops three-dimensional-porous structure with high porosity of 80%. According to the comparison it can be seen that content ratio between collagen and calcic inorganic salt as well as addition of conglutinant PLLA all have an effect on microstructure of the synthesized scaffold, additionally molecular weight of PLLA has an effect on mechanical properties. Conclusion ：The nanophase artificial bone composite scaffold synthesized by biomimetic process is one of the most promising optimal materials for clinical application no matter how judged from structure, composition and property. The various factors influencing the scaffold discussed in this article may indicate some useful modification ways according to the actual utility in the near future.     

Valvular interstitial cell seeded poly(glycerol sebacate) scaffolds: Toward a biomimetic in vitro model for heart valve tissue engineering

Tissue engineered replacement heart valves may be capable of overcoming the lack of growth potential intrinsic to current non-viable prosthetics, and thus could potentially serve as permanent replacements in the surgical repair of pediatric valvular lesions. However, the evaluation of candidate combinations of cells and scaffolds lacks a biomimetic in vitro model with broadly tunable, anisotropic and elastomeric structural–mechanical properties. Toward establishing such an in vitro model, in the current study, porcine aortic and pulmonary valvular interstitial cells (i.e. biomimetic cells) were cultivated on anisotropic, micromolded poly(glycerol sebacate) scaffolds (i.e. biomimetic scaffolds). Following 14 and 28 days of static culture, cell-seeded scaffolds and unseeded controls were assessed for their mechanical properties, and cell-seeded scaffolds were further characterized by confocal fluorescence and scanning electron microscopy, and by collagen and DNA assays. Poly(glycerol sebacate) micromolding yielded scaffolds with anisotropic stiffnesses resembling those of native valvular tissues in the low stress–strain ranges characteristic of physiologic valvular function. Scaffold anisotropy was largely retained upon cultivation with valvular interstitial cells; while the mechanical properties of unseeded scaffolds progressively diminished, cell-seeded scaffolds either retained or exceeded initial mechanical properties. Retention of mechanical properties in cell-seeded scaffolds paralleled the accretion of collagen, which increased significantly from 14 to 28 days. This study demonstrates that valvular interstitial cells can be cultivated on anisotropic poly(glycerol sebacate) scaffolds to yield biomimetic in vitro models with which clinically relevant cells and future scaffold designs can be evaluated.     

In vitro mineralization of dense collagen substrates: a biomimetic approach toward the development of bone-graft materials

Bone is an organic-inorganic composite which has hierarchical structuring that leads to high strength and toughness. The nanostructure of bone consists of nanocrystals of hydroxyapatite embedded and aligned within the interstices of collagen fibrils. This unique nanostructure leads to exceptional properties, both mechanical and biological, making it difficult to emulate bone properties without having a bone-like nanostructured material. A primary goal of our group's work is to use biomimetic processing techniques that lead to bone-like structures. In our prior studies, we demonstrated that intrafibrillar mineralization of porous collagen sponges, leading to a bone-like nanostructure, can be achieved using a polymer-induced liquid precursor (PILP) mineralization process. The objective of this study was to investigate the use of this polymer-directed crystallization process to mineralize dense collagen substrates. To examine collagen scaffolds that truly represent the dense-packed matrix of bone, manatee bone was demineralized to isolate its collagen matrix, consisting of a dense, lamellar osteonal microstructure. This biogenic collagen scaffold was then remineralized using polyaspartate to direct the mineralization process through an amorphous precursor pathway. The various conditions investigated included polymer molecular weight, substrate dimension and mineralization time. Mineral penetration depths of up to 100 μms were achieved using this PILP process, compared to no penetration with only surface precipitates observed for the conventional crystallization process. Electron microscopy, wide-angle X-ray diffraction and thermal analysis were used to characterize the resulting hydroxyapatite/collagen composites. These studies demonstrate that the original interpenetrating bone nanostructure and osteonal microstructure could be recovered in a biogenic matrix using the PILP process.     

胶原/生物活性玻璃/壳聚糖增强型复合支架

背景：生物活性玻璃/胶原复合材料具有优良的成骨活性和的生物学性能,然而其在人体环境中易降解而导致支架溃散、力学性能下降。 目的：构建具有良好力学性能、抗降解性能和骨修复特性的胶原/生物活性玻璃/壳聚糖增强型复合支架。 方法：以壳聚糖作为分散剂,将生物活性玻璃粉体预先在壳聚糖溶液中均匀分散,然后与胶原溶液混合,结合冷冻干燥法制备多孔胶原/生物活性玻璃/壳聚糖增强型复合骨修复支架。采用傅里叶变换红外光谱仪、场发射扫描电子显微镜、X射线衍射仪、动态生物力学试验机等对复合支架的结构和性能进行表征。 结果与结论：由于壳聚糖和生物活性玻璃粉体在微酸性环境下的电荷吸引,使在壳聚糖中预分散的生物活性玻璃颗粒在复合支架中分散更均匀;壳聚糖的引入大量增加了机体中的羟基和氨基,使分子间的相互作用增强,显著提高了材料的抗压模量和强度;壳聚糖和胶原在分子尺度的混合,使胶原分子被壳聚糖包裹,降低了胶原酶对胶原分子的酶切能力,显著提高了复合支架的抗胶原酶解性;壳聚糖分子使生物活性玻璃颗粒更均匀的包裹在大分子基相中,减少了生物活性玻璃颗粒的团聚和暴露,导致复合支架在模拟体液中的矿化活性略微降低。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

牛松质骨在疲劳过程中微孔形成机制的研究

采用配置疲劳台的扫描电镜 ,直接观察牛松质骨疲劳损伤的动态过程 ,研究牛松质骨在疲劳载荷下微孔形成过程及机制 ,探讨骨质疏松骨小梁刚度、脆性增加机理。试验发现在拉伸疲劳载荷下垂直骨小梁的板层骨塑性变形 ,并形成大量微孔 ,微孔内尚有撕裂的胶原纤维。在压缩疲劳载荷下 ,横行骨小梁的板层骨胶原纤维在载荷作用下逐渐转向、颈缩、胶原纤维内原纤维滑移 ,与无机质脱黏 ,断裂 ,并回缩形成微孔。研究提示在疲劳载荷下 ,骨胶原纤维颈缩、滑移 ,与骨矿化物脱黏、形成微孔 ,是松质骨疲劳损伤的常见形式之一。骨小梁内板层骨形成的微孔的生物学修复可能主要由矿化物的沉积完成 ,而变细、抗拉强度下降的断裂骨胶原纤维未能完全更新 ,会逐渐导致骨小梁骨脆化、刚度相对增加 ,成为老年性骨质疏松发生的机制之一     

Injectable calcium sulfate/mineralized collagen-based bone repair materials with regulable self-setting properties

An injectable and self-setting bone repair materials (nano-hydroxyapatite/collagen/calcium sulfate hemihydrate, nHAC/CSH) was developed in this study. The nano-hydroxyapatite/collagen (nHAC) composite, which is the mineralized fibril by self-assembly of nano-hydrocyapatite and collagen, has the same features as natural bone in both main hierarchical microstructure and composition. It is a bioactive osteoconductor due to its high level of biocompatibility and appropriate degradation rate. However, this material lacks handling characteristics because of its particle or solid-preformed block shape. Herein, calcium sulfate hemihydrate (CSH) was introduced into nHAC to prepare an injectable and self-setting in situ bone repair materials. The morphology of materials was observed using SEM. Most important and interesting of all, calcium sulfate dihydrate (CSD), which is not only the reactant of preparing CSH but also the final solidified product of CSH, was introduced into nHAC as setting accelerator to regulate self-setting properties of injectable nHAC/CSH composite, and thus the self-setting time of nHAC/CSH composite can be regulated from more than 100 min to about 30 min and even less than 20 min by adding various amount of setting accelerator. The compressive properties of bone graft substitute after final setting are similar to those of cancellous bone. CSD as an excellent setting accelerator has no significant effect on the mechanical property and degradability of bone repair materials. In vitro biocompatibility and in vivo histology studies demonstrated that the nHAC/CSH composite could provide more adequate stimulus for cell adhesion and proliferation, embodying favorable cell biocompatibility and a strong ability to accelerate bone formation. It can offer a satisfactory biological environment for growing new bone in the implants and for stimulating bone formation.