Preparation of new tissue engineering bone-CPC/PLGA composite and its application in animal bone defects

To investigate the feasibility of implanting the biocomposite of calcium phosphate cement (CPC)/polylactic acid-polyglycolic acid (PLGA) into animals for bone defects repairing, the biocomposite of CPC/PLGA was prepared and its setting time, compressive strength, elastic modulus, pH values, phase composition of the samples, degradability and biocompatibility in vitro were tested. The above-mentioned composite implanted with bone marrow stromal cells was used to repair defects of the radius in rabbits. Osteogenesis was histomorphologically observed by using an electron-microscope. The results show that compared with the CPC, the physical and chemical properties of CPC/PLGA composite have some differences in which CPC/PLGA composite has better biological properties. The CPC/PLGA composite combined with seed cells is superior to the control in terms of the amount of new bones formed after CPC/PLGA composite is implanted into the rabbits, as well as the speed of repairing bone defects. The results suggest that the constructed CPC/PLGA composite basically meets the requirements of tissue engineering scaffold materials and that the CPC/PLGA composite implanted with bone marrow stromal cells may be a new artificial bone material for repairing bone defects because it can promote the growth of bone tissues.     

Stiffness compatibility of coralline hydroxyapatite bone substitute under dynamic loading

When hydroxyapatite bone substitutes are implanted in human bodies, bone tissues will grow into their porous structure, which will reinforce their strength and stiffness. The concept of mechanical compatibility of bone substitutes implies that their mechanical properties are similar to the bone tissues around, as if they were part of the bone. The mechanical compatibility of bone substitutes includes both static and dynamic behavior, due to the mechanical properties of bone depending on the strain rate. In this study, split Hopkinson pressure bar technique (SHPB) was employed to determine the dynamic mechanical properties of coralline hydroxyapatite, bones with and bones without organic components, and their dynamic stress-strain curves of the three materials were obtained. The mechanical effects of collagens in bone were assessed, by comparing the difference between the Young’s moduli of the three materials. As the implanted bone substitute becomes a part of bone, it can be regarded as an inclusion composite. The effective modulus of the composite was also evaluated in order to estimate its mechanical compatibility on stiffness. The evaluated result shows that the suitable porosity of HA is 0.8, which is in favor of both static and dynamic stiffness compatibility. Supported by the Tianjin Natural Science Foundation (Grant No. 05YFJMJC10500)     

The transformation of calcium phosphate bioceramics<Emphasis Type="Italic">in vivo</Emphasis>

To study the transformation process of calcium phosphate bioceramic in vivo, biodegradable porous β-tricalcium phosphate ceramics (β-TCP) were used in this experiment. The materials (ø5×8mm) were implanted in the tibia of rabbits. The β-TCP ceramics with bone tissue were retrieved, and treated for histology, and then observed by using a scanning electron microscope (SEM) and an electron probe X-ray microanalyzer (EMPA) every month. The results show that β-TCP ceramics bond to bone directly, new bones are forming and maturing with materials continuous degrading, and the materials are nearly replaced by the formed bone finally. Parts of the materials were degraded, absorpted and recrystallized, the others dispersped on the cancellous bone and the Haversian lamella with an irregular arrangement incorporating in bone formation directly by remodeling structure.     

Eetopie Bone Formation in vivo Indueed by a Novel Synthetie Peptide Derived from BMP-2 Using Porous Collagen Scaffolds

To investigate the osteoinductive and ectopicly osteogenic effects of a novel peptide P24 derived from bone morphogenetic protein 2 （BMP2）, biodegradable collagen scaffolds （CS） were used to load BMP-2-derived peptide solutions with different concentrations （0.4 mg peptide/CS, 0.1 mg peptide/CS and pure CS, respectively）, and the implants were implanted into muscular pockets on the back of Wistar rats. Radiographs and histological analysis were performed to evaluate the ectopic bone effects. Active ectopic bone formation was seen in both groups containing the peptide at different concentration （0.4 mg and 0.1 mg）, whereas no bone formation and only fibrous tissue was seen in the pure CS group. The new bone formation induced by the peptide P24 displayed a dose-dependent and time-dependent efficiency. The new bone formation in the 0.4 mg peptide/CS group significantly increased than that of the 0.1 mg peptide/CS group. This novel BMP-2-derived peptide had excellent osteoinductive and ectopicly osteogenic properties which were similar to those of BMP2.     

Tissue response of an osteoinductive bioceramic in bone defect rabbit model

HA/TCP and HA rods (?5 mm×10 mm) were made for implantation in New Zealand white rabbit with different condition. Sixty three rabbit were divided into three groups: group 1 (n=18), group 2 (n=27) and group 3 (n=18). In group 1, 10 mm radius was defected, and one HA/TCP rod was implanted in the muscle a distant away from the bone defect area. In group 2, also, 10 mm radius was defected, one HA rod was implanted in the muscle a distant away from the bone defect area. In group 3, two HA/TCP rods were implanted in the dorsal muscle of the rabbit with bone intact. Histological observation showed that in group 1, some new bone was found only two months after implantation (n=2), and obvious immature woven bone could be observed in these bioceramics from the 3^rd month on. However, in group 3, bone began to be found 6 months after implantation (n=2). In group 2, we could not find any bone tissue up to 9 month’s observation. These results suggest that, first, the bone defect model could significantly accelerate bone formation at non-osseous sites in rabbits; second,. HA/TCP bioceramics were confirmed with osteoinductive property while HA bioceramics without osteoinductive property nearly. Thus, bone defect might be a good animal model for further researches for osteoinductive bioceramics.     

增材制造可降解人工骨的研究进展——从外形定制到性能定制

频繁的创伤、肿瘤切除等引起的骨缺损导致人们对人工骨的需求大大增加,可降解人工骨越来越受到研究人员的重视.结合课题组在过去5年的研究,回顾骨修复材料的背景和发展现状,总结无机骨修复材料（生物活性陶瓷）和骨修复支架的制造方法,尤其是基于增材制造（3D打印）的方法.重点阐述3D打印可降解人工骨用于骨组织修复及再生在力学性能、成骨性能、降解性能和生物活性等几个方面的研究现状,并对可降解人工骨的未来发展方向作了展望.目前人工骨定制已经从简单的形状定制逐步过渡到骨性能定制,人工骨的个性化定制将是今后的研究重点.     

Biocompatibility Studies on Bone Marrow Stromal Cells with Chitosan-gelatin Blends

1　IntroductionSuccessfulmanagementofcartilagedefectsremainsamajorclinicalchallengetoorthopedicsurgeons .Theneedformoreeffectivemethodsofrepairingcartilagedefectshaspromptedinvestigationintotheutilityoftissueengi neeringapproachesrecently .Thechoiceofbiom…     

多孔磷酸三钙陶瓷骨内植入后界面变化观察

将多孔磷酸三钙陶瓷植入Ｗｉｓｔａｒ大鼠股骨髁骨腔洞内，扫描电镜观察见界面处新骨与材料直接紧密接触，新骨经历由交织骨向极层骨的转变，材料晶粒间连接中断，体积缩小，边缘缺损或不规则，微孔扩大成形成微空洞，同时，界面处可见破骨细胞；Ｘ线能谱（ＥＤＡＸ）显示界面处新骨中Ｃａ含量增高，Ｃａ／Ｐ比高达２．１；电子探针（ＥＰ）扫描显示界面处新骨与材料中Ｃａ浓度接近，材料周围有游离Ｃａ分布．这些结果表明界面处材料活跃的降解交化。     

Preparation of filling porous osteoconduction materials and its animal experiment study

Titanium rods were processed into implant samples with cavity and groove in which was filled with HAP/β-TCP porous osteoconduction composite materials in order to increase the mechanical stability of the implant in vivo.The phase compositions of the composite was characterized by X-ray diffraction (XRD) and scanning electron microscopy(SEM).Histological evaluation showed that the biogradable composite could enhanced the ability of new bone formation.The composite can conduct new bone tissue growing into the cavities gradually after implanted into animal,and then achieve mechanical fixation.The filling biogradable compound exhibited excellent biocompatibility,which combined with the new bone tissues tightly without inflammation and loosing.     

基于均匀化理论的骨小梁损伤刚度

用相对线密度ρ描述骨小梁上裂纹的分布;利用均匀化方法研究了微裂纹的密度、长度和方向对骨小梁刚度的影响。骨小梁的刚度与微裂纹的长度密切相关,当微裂纹长度增加时,与微裂纹垂直方向上的骨小梁刚度下降很快;骨小梁的刚度与微裂纹的密度密切相关,当微裂纹的密度增大时,3个方向上的刚度以相同的比率缓慢下降,以对与裂纹垂直方向的E影响最大;骨小梁的刚度与裂纹的方向也有密切关系。松质骨的力学性质与其微结构和骨小梁的力学性质有关;松质骨的损伤主要与骨小梁的损伤和损伤分布有关。     

一种描述松质骨骨质疏松过程的计算模型

为了定量描述松质骨的骨质疏松过程,依据骨的功能适应性和力学调控系统理论,遵循骨重建的生理过程,提出了一个带有时间历程的计算模型,模拟了废用引起的骨质疏松,并讨论了峰值骨量对松质骨骨质疏松过程的影响。结果表明:模拟废用引起的骨质疏松过程与实际生理过程相近,峰值骨量较高能够延迟骨质疏松发生的时间。     

TGF-beta 1 Gene-Activated Matrices Regulated the Osteogenic Differentiation of BMSCs

Poly （lactic acid/glycolic acid/asparagic acid-co-polyethylene glycol）（PLGA-[ASP-PEG]） scaffold materials were linked with a novel nonviral vector （K）16GRGDSPC through cross linker Sulfo- LC-SPDP to construct a new type of nonviral gene transfer system. Eukaryotic expressing vector containing transforming growth factor beta 1 （pcDNA3-TGFβ1） was encapsulated by the system. Bone marrow stromal cells （BMSCs） obtained from rabbit were cultured on PLGA-[ASP-PEG] modified by （K）16GRGDSPC and TGF-β1 gene and PLGA-[ASP-PEG] modified by （K）16GRGDSPC and empty vector pcDNA3 as control. The expressions of osteogenic makers of the BMSCs cultured on the TGF-β1 gene-activated scaffold materials were found significantly higher than those of the control group （P〈0.05）. A brand-new way was provided for regulating seed cells to directionally differentiate into osteoblasts for bone defect restoration in bone tissue engineering.     

Organic-inorganic bio-composite as bone substitute

Organic-inorganic composite biomaterial (HA-TCP-BMP) used as bone substitutes and the fabrication process are described in this paper. The quantitative calculation ofβ-whithokite presented in sintered material is about 14%–18% and the ratio of Ca/P is about 1.61. The influences of the composition and structure on the bone forming properties and biologic effects are discussed. Meanwhile, the results of clinical application of the composite materials are viewed. The research results show that the composite material can be completely degradated in controlle time and at the operation site new formed bone can fully replace the implanted material. Project supported by the National Natural Science Fundation of China Synopsis of the author Ruan Jianmin, associated professor, born in 1957, specializing in powder metallurgy as well as bioceramic materials.     

酶法制取骨明胶理论初探

本文利用差热分析技术研究了不溶性骨胶原纤维的变性情况，并采用氨基酸分析和凝胶过滤色谱技术对酶法制取骨明胶的理论进行了初步探讨。     

一种松质骨微结构图像分析的新方法及其应用

采用实验和计算机图像分析相结合的方法,对松质骨微结构进行分析,研究松质骨孔隙率沿不同方向的分布规律.利用光镜观察和自行设计的图像分析软件,计算了松质骨切片表面的总面积、骨基质的面积、孔隙的面积,进而得出该松质骨切片的孔隙率.分析结果表明:对胫骨近端松质骨或远端松质骨,孔隙率沿轴向靠近密质骨逐渐减小,而沿横向基本不变,松质骨材料可看作横观各向同性的液饱和多孔材料,利用本方法和设计的图像分析软件可较为准确地检测松质骨孔隙率.     

Fast garment simulation with aid of hybrid bones

A data-driven method was proposed to realistically animate garments on human poses in reduced space. Firstly, a gradient based method was extended to generate motion sequences and garments were simulated on the sequences as our training data. Based on the examples, the proposed method can fast output realistic garments on new poses. Our framework can be mainly divided into offline phase and online phase. During the offline phase, based on linear blend skinning(LBS), rigid bones and flex bones were estimated for human bodies and garments, respectively. Then, rigid bone weight maps on garment vertices were learned from examples. In the online phase, new human poses were treated as input to estimate rigid bone transformations. Then, both rigid bones and flex bones were used to drive garments to fit the new poses. Finally, a novel formulation was also proposed to efficiently deal with garment-body penetration. Experiments manifest that our method is fast and accurate. The intersection artifacts are fast removed and final garment results are quite realistic.     

人工骨快速成型制造的研究进展

随着生活水平的日益提高,人们对骨损伤的修复要求也越来越高,人工骨骼的制造是骨损伤修复过程中的关键步骤,应用快速成型技术来制造人工骨骼能够大幅度降低骨骼制造的难度.国内外学者对人工骨骼的制造做了大量的研究,在人工骨骼新材料的研究和快速成型制造人工骨的新方法等方面都取得了积极的研究成果.本文结合近年来相关的文献资料,对人工骨骼制造的研究成果进行了系统综述,主要介绍了制作人工骨骼的新材料的研究状况和应用快速成型技术加工人工骨骼的一些新型工艺方法的发展状况,对快速成型技术的软件发展也做了介绍.随着人工骨骼快速成型制造研究的快速发展,人工骨骼的制作质量将得到大大提高,制作成本将大幅度降低.     

Bone Formation Process of β-TCP Ceramics with Tetracycline Tracing

To study the new bone formation in the bone defect area after implantation, the tetracycline tracing method was used. The results show that new bone formed in 1 month, and the formation rate of new bone was very high (8. 164 μm/day), considerably faster than that of control groups (3.219 μm/day). The new bone grew up quickly and β_TCP particles were surrounded by double fluorescence bands which became more obvious. The new bone formation rate was maximal at 2 months, and then gradually reduced. The rate was steady at 4 months, and then reduced to resembling as the normal physiologic metabolism of bone, which indicated the implanted materials were completely replaced by bone. Calcium phosphate materials had the ability of osteoconduction.     

The enhancement of osteogenesis by scaffold based on mineralized recombinant human-like collagen loading with rhBMP-2

A biomimetic scaffold based on mineralized recombinant collagen, nano-hydroxyapatite/recombinant human-like collagen/poly(lactic acid) (nHA/RHLC/PLA), was prepared with recombinant human bone morphogenic protein-2 (rhBMP-2) for improving the osteoinductive property of the scaffold. The nHA/RHLC/PLA scaffolds loaded with 10 μg rhBMP-2 and the unloaded scaffolds were implanted subcutaneously in the rat model. The osteogenetic capacity of these composites was evaluated by CT scan, ALP activity test and histological observation at 4 and 8 weeks after implantation. The experimental results indicated that the osteogenic capability of the scaffolds loaded with rhBMP-2 was superior to the unloaded scaffold. It was concluded that rhBMP-2 can enhance the osteoinductive property of the nHA/RHLC/PLA scaffold and the nHA/RHLC/PLA scaffold loaded with rhBMP-2 have the good potential of being used in bone tissue engineering.     

骨质瓷用合成骨炭的研制

采用固相合成法,用廉价的碳酸钙和磷酸氢钙等作原料,在特定温度条件下进行固相合成反应,可以得到一种用于生产陶瓷用品的粉末状合成骨炭,其主要成分是羟基磷酸钙。将合成得到的骨炭产品按照骨质瓷器的烧制条件,进行了烧制骨质瓷的实验验证,实验结果表明所研制的合成骨炭,不仅能满足骨质瓷器生产的质量要求,同时合成骨炭的价格低廉、生产过程清洁环保,合成骨炭产品的成本比天然骨炭的成本低40%左右。