不同骨科植入物对放射治疗的影响

分析商用的不锈钢植入物、钛基合金植入物以及自制的碳纤维植入物在放射诊断中的影像学区别及对放射治疗剂量的影响,探讨碳纤维植入物在放射治疗方面的应用前景.把3种不同材质的骨科植入物通过手术先后植入同一只家猪的同一只后腿,用普通模拟定位机和CT模拟定位机观察不同材质的骨科植入物对影像的影响,进而利用放射治疗计划系统分析不同植...     

3D打印钛金属骨科植入物应用现状

3D打印技术近年来在骨科植入医疗器械领域发展迅速,由于其能够根据患者需求个性化地定制植入物形状,并且精确控制植入物的复杂微观结构,从而实现植入物外形和力学性能与人体自身骨的双重适配。生物医用钛及钛合金作为目前骨科植入物的主要原材料,具有优越的生物相容性,与3D打印技术结合,成为各国科学家以及医疗器械厂家研发的热点,促进3D打印钛金属骨科植入物的商业化。针对3D打印钛金属骨科植入物的特点、钛金属粉末要求、已上市产品情况、临床研究、存在的问题以及标准和审评规范等的现状与发展进行论述和展望。     

Tissue Engineering Strategies for the Regeneration of Orthopedic Interfaces

A major focus in the field of orthopedic tissue engineering is the development of tissue engineered bone and soft tissue grafts with biomimetic functionality to allow for their translation to the clinical setting. One of the most significant challenges of this endeavor is promoting the biological fixation of these grafts with each other as well as the implant site. Such fixation requires strategic biomimicry to be incorporated into the scaffold design in order to re-establish the critical structure–function relationship of the native soft tissue-to-bone interface. The integration of distinct tissue types (e.g. bone and soft tissues such as cartilage, ligaments, or tendons), necessitates a multi-phased or stratified scaffold with distinct yet continuous tissue regions accompanied by a gradient of mechanical properties. This review discusses tissue engineering strategies for regenerating common tissue-to-tissue interfaces (ligament-to-bone, tendon-to-bone, or cartilage-to-bone), and the strategic biomimicry implemented in stratified scaffold design for multi-tissue regeneration. Potential challenges and future directions in this emerging field will also be presented. It is anticipated that interface tissue engineering will enable integrative soft tissue repair, and will be instrumental for the development of complex musculoskeletal tissue systems with biomimetic complexity and functionality.     

骨组织工程支架材料

目的寻找理想的支架材料,探讨目前骨组织工程研究的热点.方法本文对用于骨组织工程支架材抖的天然生物衍生材料、聚合物类材料、陶瓷材料及其复合材料等的研究现状进行综述.结果分析了这些材料的优缺点,并对骨组织工程支架材料发展趋势进行了展望.结论骨组织工程支架材料的研究甚多,进展也很快,但尚未找到一种理想的材料,还有很多的有待解决的问题.     

Polymeric Scaffolds for Bone Tissue Engineering

Bone tissue engineering is a rapidly developing area. Engineering bone typically uses an artificial extracellular matrix (scaffold), osteoblasts or cells that can become osteoblasts, and regulating factors that promote cell attachment, differentiation, and mineralized bone formation. Among them, highly porous scaffolds play a critical role in cell seeding, proliferation, and new 3D-tissue formation. A variety of biodegradable polymer materials and scaffolding fabrication techniques for bone tissue engineering have been investigated over the past decade. This article reviews the polymer materials, scaffold design, and fabrication methods for bone tissue engineering. Advantages and limitations of these materials and methods are analyzed. Various architectural parameters of scaffolds important for bone tissue engineering (e.g. porosity, pore size, interconnectivity, and pore-wall microstructures) are discussed. Surface modification of scaffolds is also discussed based on the significant effect of surface chemistry on cells adhesion and function.     

骨组织工程支架材料

目的寻找理想的支架材料，探讨目前骨组织工程研究的热点。方法本文对用于骨组织工程支架材抖的天然生物衍生材料、聚合物类材料、陶瓷材料及其复合材料等的研究现状进行综述。结果分析了这些材料的优缺点，并对骨组织工程支架材料发展趋势进行了展望。结论骨组织工程支架材料的研究甚多，进展也很快，但尚未找到一种理想的材料，还有很多的有待解决的问题。     

Detailed Process of Bone Remodeling After Achievement of Osseointegration in a Rat Implantation Model

Osseointegration is regarded as the most appropriate implant‐bone interface in dental implantation. However, damaged bone with empty osteocytic lacunae driven by implant cavity preparation remains even after the completion of osseointegration. Although previous studies have suggested the occurrence of bone remodeling around implants, information on its detailed process is meager. Our study aimed to examine the fate of bone around titanium implants after the establishment of osseointegration on an animal model using the rat maxilla. Titanium implants were inserted into prepared bone cavities of the rat maxilla. Bone formation and maturation processes were evaluated by double staining for alkaline phosphatase and tartrate‐resistant acid phosphatase, immunohistochemistry for bone matrix proteins, vital staining with calcein, and elemental mapping with an electron probe microanalyzer. Bone with empty osteocytic lacunae or pyknosis remained between the intact preexisting and newly formed woven bones at post 1 month. It gradually decreased to disappear completely by active bone remodeling with a synchronized coordination of alkaline phosphatase‐positive osteoblasts and tartrate‐resistant acid phosphatase‐reactive osteoclasts at post 3 months, thickening to be replaced by compact bone. Dynamic labeling showed two clear lines in the newly formed bone around the implant through this experimental period. Electron probe microanalyzer analysis demonstrated chronologically increased levels of Ca and P in the newly formed bone identical to those in the surrounding bone at post 2.5 months. These findings indicate that continuous bone remodeling after the achievement of osseointegration causes replacement of the damaged bone by compact bone as well as an improvement in bone quality. Anat Rec, 2009. © 2008 Wiley‐Liss, Inc.     

Effect of Angiogenesis in Bone Tissue Engineering

The reconstruction of large skeletal defects is still a tricky challenge in orthopedics. The newly formed bone tissue migrates sluggishly from the periphery to the center of the scaffold due to the restrictions of exchange of oxygen and nutrition impotent cells osteogenic differentiation. Angiogenesis plays an important role in bone reconstruction and more and more studies on angiogenesis in bone tissue engineering had been published. Promising advances of angiogenesis in bone tissue engineering by scaffold designs, angiogenic factor delivery, in vivo prevascularization and in vitro prevascularization are discussed in detail. Among all the angiogenesis mode, angiogenic factor delivery is the common methods of angiogenesis in bone tissue engineering and possible research directions in the future.

     

Effect of micro-roughening of poly(ether ether ketone) on bone marrow derived stem cell and macrophage responses,and osseointegration

Poly(ether ether ketone) (PEEK) has emerged as a candidate to replace metal implants because of its satisfactory mechanical properties, radiolucency, and lack of metal allergy. However, PEEK lacks osseointegration ability limiting its clinical applications. To overcome this problem, we prepared PEEK with a micro-rough surface using the sandblast method to modulate its osseointegration property; the sandblast method is simple, cost-effective, and is already applied to clinical metal implants. The surface roughness of the sandblasted PEEK was about 2.3 μm, whereas that of mirror-polished PEEK was 0.06 μm. Rat bone marrow-derived mesenchymal stem cells (RMSCs) showed higher proliferation, osteocalcin (OC) expression and bone-like nodule formation on micro-roughened PEEK compared with those cultured on mirror-polished PEEK, suggesting that micro-roughening facilitated RMSCs proliferation and differentiation. The micro-roughened surface slightly mitigated secretion of inflammatory C-C motif chemokine 2 (CCL-2) from lipopolysaccharide (LPS)-stimulated macrophages, but not of tumor necrosis factor α (TNFα) and interleukin-6 (IL-6). Finally, to compare osseointegration, specimens were implanted in rat femur bone marrow cavities, and then the pull-out force was measured. The pull-out force of micro-roughened PEEK was about four times higher than that of the mirror-polished PEEK. These results showed that micro-roughening of PEEK using the sandblast method was able to improve osseointegration, partly through elevating proliferation and differentiation of RMSCs.     

Rapid Mineralization of Electrospun Scaffolds for Bone Tissue Engineering

We investigated different techniques to enhance calcium phosphate mineral precipitation onto electrospun poly(_L-lactide) (PLLA) scaffolds when incubated in concentrated simulated body fluid (SBF), 10×SBF. The techniques included the use of vacuum, pre-treatment with 0.1 M NaOH and electrospinning gelatin/PLLA blends as means to increase overall mineral precipitation and distribution throughout the scaffolds. Mineral precipitation was evaluated using environmental scanning electron microscopy, energy dispersive spectroscopy mapping and the determination of the mineral weight percents. In addition we evaluated the effect of the techniques on mechanical properties, cellular attachment and cellular proliferation on scaffolds. Two treatments, pre-treatment with NaOH and incorporation of 10% gelatin into PLLA solution, both in combination with vacuum, resulted in significantly higher degrees of mineralization (16.55 and 15.14%, respectively) and better mineral distribution on surfaces and through the cross-sections after 2 h of exposure to 10×SBF. While both scaffold groups supported cell attachment and proliferation, 10% gelatin/PLLA scaffolds had significantly higher yield stress (1.73 vs 0.56 MPa) and elastic modulus (107 vs 44 MPa) than NaOH-pre-treated scaffolds.     

骨髓间充质干细胞在骨组织工程中的应用

间充质干细胞可以分化为成骨细胞、成纤维细胞、神经细胞等多种组织细胞。研究者从骨髓中分离提取骨髓间充质干细胞 ,并通过诱导和体外培养使之分化为成骨细胞 ,作为骨组织工程的种子细胞。     

骨组织工程支架材料表面修饰的试验研究

观察骨髓基质细胞 (BMSC)在吸附了多聚赖氨酸 (Poly -L -Lysine,PLL)的羟基磷灰石 (HA)上的生长情况。探讨改进材料表面活性 ,促进种子细胞黏附和生长的方法。利用组织工程学的方法 ,将体外培养的BMSC种植于吸附了多聚赖氨酸的HA上 ,立体培养一周 ,用环境扫描电镜和倒置相差显微镜观察细胞的生长情况。结果表明 ,细胞在体外可以立体培养成活 ,吸附了多聚赖氨酸的HA上细胞较多。多聚赖氨酸可以改善HA的表面活性 ,促进细胞的黏附和生长。     

植入性下肢骨植入体周围骨应力分布的三维有限元分析

基于CT扫描数据,针对低、中和高位下肢截肢步行最大生理载荷情况下,建立植入性下肢骨植入体及人体股骨三维有限元分析模型,计算结果表明：假肢的最大应力位于骨植入体外力传递杆靠近残肢残端,是假肢周期性载荷的疲劳破坏点;随截肢部位上移,股骨内应力最大值迅速增大;在植入体与股骨接触部位,存在严重的应力屏蔽,应力集中的两个区域分布在植入体末端和股骨四分之三处,可能导致骨质废用性和病理性吸收,影响假肢中长期使用寿命。本研究还表明,股骨的自然曲率对骨内应力分布有较大的影响,是不能忽略的因素。本文所获结果可为植入假肢的设计研究提供依据。     

骨组织工程用聚磷酸钙的结构和性能的研究

多孔聚磷酸钙（Calcium polyphosphate，CPP）生物陶瓷是一种新型的骨组织工程支架材料，国外有研究表明聚磷酸钙作为骨组织工程支架材料具有良好的生物相容性及可降解性。通过对原料煅烧过程的研究，探索了聚合度的计算方法，制备出不同聚合度的材料。通过对材料烧结温度的试验，制得了不同晶型的聚磷酸钙多孔材料。在Tris—HCl缓冲液中进行的体外降解实验表明，CPP多孔支架材料是可控降解的，不同聚合度和晶型的支架材料力学强度和降解性能不同。随着聚合度的增加，材料的力学强度增大，降解速率变小；非晶态的CPP17d就可以完全降解，7晶型的CPP25d可完全降解，β和α晶型的CPP降解缓慢，30d分别降解了大约12％和5％。因此聚磷酸钙是一种很有前途的骨组织工程支架材料，凭借其独特的无机聚合物结构及降解性能，有望实现可控速率的降解。     

Analysis of the Basic Characteristics of Osteogenic and Chondrogenic Cell Lines Important for Tissue Engineering Implants

Bulletin of Experimental Biology and Medicine - We isolated and characterized cultures of bone and cartilage tissue cells of laboratory minipigs. The size and morphological features of adherent...     

体内组织工程骨的BMP4 mRNA表达

比较磷酸钙陶瓷构建的体内组织工程骨和自然再生骨的BMP4 mRNA表达.制备Φ5 mm×8 mm的骨诱导性磷酸钙陶瓷20粒并分别植入5只狗的竖直肌内,同时,拔除狗的一颗磨牙形成自然再生骨模型.术后1、2、4、12及24周,取出体内组织工程骨及自然再生骨.提取总 RNA, 经逆转录成 cDNA 后,用实时相对定量PCR的方法检测 BMP4 mRNA 的表达.结果表明:在本实验周期,BMP4 mRNA 在磷酸钙陶瓷构建的体内组织工程骨中的表达量高于在自然再生骨中的表达量,但BMP4 mRNA 在体内组织工程骨和自然再生骨中有相同的基因表达时序性.作为类似自体骨的骨替代物,磷酸钙陶瓷构建的体内组织工程骨具有切实可行的应用前景.     

Tissue Engineering Construct on the Basis of Multipotent Stromal Adipose Tissue Cells and Osteomatrix for Regeneration of the Bone Tissue

We developed a new method of creation of tissue engineering constructs for regeneration of the bone tissue based on the principle of free distribution of cells in a fibrin clot within a scaffold. The tissue engineering construct includes multipotent stromal adipose tissue cells committed in osteogenic lineage, platelet-rich plasma, and resorbed material on the basis of xenogeneic bone collagen. The culture of bone progenitor cells was characterized by the main markers of osteoblastic differon. The material meets all requirements for materials intended for tissue engineering. An innovative high-technological tissue engineering product for clinical application is prepared.     

骨组织工程中调节巨噬细胞行为促进骨愈合的策略

骨组织工程将材料作为骨再生支架植入缺损局部,帮助完成骨愈合。近年来随着骨免疫学的发展,人们意识到巨噬细胞的免疫应答决定着材料植入的成败。巨噬细胞具有多样性和可塑性,可以根据环境信号极化为M1样(促炎)和M2样(抑炎)表型,在骨愈合的不同阶段发挥作用。巨噬细胞的迁移、增殖、极化等行为对材料特性敏感。对目前在骨组织工程中,通过改变材料的物理特性、表面化学特性以及生物特性,设计能主动调节巨噬细胞行为的材料,从而促进骨愈合的策略进行了概括总结,相关策略包括：增加材料的粗糙度、大孔结合纳米结构、合适的电信号或机械信号、中性或阴离子表面、增加亲水性、利用免疫调节材料或向局部输送免疫活性物质等,以期为设计具有良好免疫调节性的骨组织工程材料提供思路。     

骨组织工程MSCs及其种植载体的研究进展

骨髓基质干细胞 (MSCs)是存在骨髓组织中一种具有多项分化潜能的前体细胞 ,也是骨组织工程中最常用的种子细胞。增加MSCs的了解并选择适当的载体支架用于MSCs的种植是当前骨组织工程研究中的紧迫任务 ,同时掌握MSCs与载体支架的接种技术和相关的辅助方法也是骨组织工程研究中不可缺少的重要环节。本文针对国内外在此方面的研究进展进行综述。