晶须碳酸钙／聚L-乳酸复合材料的合成与实验研究

目的 合成晶须碳酸钙／聚L-乳酸复合材料，并评价其生物相容性、力学性能及降解性。方法 采用溶液共混法聚合晶须碳酸钙／聚L-乳酸复合材料，对其进行初始强度及降解后的力学测定、体外细胞共培养及降解速率的测定。结果 复合材料对细胞无毒性，聚L-乳酸加入晶须碳酸钙后，力学性能均有不同程度提高且降解失重率减小。结论晶须碳酸钙与聚L-乳酸复合后，提高了材料的力学性能，延缓了降解，并具有一定的生物活性。     

新型聚左旋乳酸/磷酸三钙多孔材料构建工程化骨的体外研究

由两种或两种以上不同材料优化而成的组织工程替代材料是近年来骨组织工程发展的新趋势[1] ,这些复合材料可望获得比单种材料更优良的物理化学性能、生物相容性和生物降解性能。本研究旨在检测聚左旋乳酸与磷酸三钙的复合材料的生物性能和细胞承载能力,为组织工程化骨的构建奠定实验基础。一、材料和方法1.PLLA/TCP复合材料的制备:实验方法见文献[2 ]。2 .PLLA/TCP复合材料孔径、孔隙率及力学性能的检测:材料经常规处理,扫描电镜下观察其空隙情况,测定出孔径。用排液法测定其孔隙率。所选择的液体为乙醇,因为它能和PLLA/TCP很好的…     

载阿霉素聚氰基丙烯酸正丁酯纳米粒对L-02细胞的毒性研究

目的:检验载阿霉素聚氰基丙烯酸正丁酯纳米粒(ADM-PBCA-NP)对人肝细胞株L-02细胞的毒性。方法:体外培养人肝细胞株L-02，检测各组不同纳米粒浓度培养上清液中乳酸脱氢酶（LDH）的活性；用噻唑蓝（MTT）法检测L-02在与ADM-PBCA-NP，阿霉素（ADM）和空白纳米粒(PBCA-NP)共同培养的条件下对肝细胞的毒性，通过对不同浓度PBCA-NP的溶血试验测定其生物相容性。结果:MTT结果显示，ADM组，ADM-NP组，PBCA-NP组在 10-6 mol/L的浓度范围内，细胞毒性均为1级，即对细胞无害。各组肝细胞L-02培养上清液中LDH活性的测定无统计学差异。结论:在10-6 mol/L浓度范围内，ADM-NP和PBCA-NP对肝细胞L-02无明显毒性作用；在一定的浓度范围内细胞相容性良好，不会引起溶血。     

聚L-乳酸修饰的聚丙烯疝补片的研制及动物实验研究

目的将聚L-乳酸修饰的聚丙烯补片应用于动物实验,进一步验证补片的防粘连效果。方法聚L-乳酸修饰的聚丙烯补片置入腹腔并覆盖腹腔缺损,同时与聚丙烯补片为对照组,通过腹腔内粘连面积、粘连程度、组织病理学改变等检查了解补片粘连情况。结果单纯聚丙烯组术后死亡率高,剖腹探查发现补片表面与腹腔脏器发生直接粘连,粘连面积广泛,粘连程度重。聚L-乳酸修饰的聚丙烯组补片表面亦有粘连,主要集中在补片边缘粘连面积、程度较轻。结论聚L-乳酸修饰的聚丙烯平片是可行的,动物实验表明聚L-乳酸修饰的聚丙烯补片可以减少动物的腹腔内粘连。     

携载rhBMP-2微球的新型可注射自凝固复合人工骨的制备及特性研究

[目的]制备一种具有良好降解性和成骨活性、可注射的自凝固新型骨修复材料。[方法]制备携载rhBMP-2的聚乳酸与聚乙醇酸共聚物（PLGA）微球，并将其与rhBMP-2／磷酸钙骨水泥（CPC）复合，制备出rhBMP-2／PLGA微球／CPC复合人工骨。探讨了材料的特性，包括形貌、固化时间、抗压强度及反映材料体外降解速度的指标一体外降解液Ca、P浓度变化，测定复合材料rhBMP乏的释药速度及体外诱导MSCs细胞成骨分化的能力。[结果]与单纯CPC-rhBMP-2相比，复合材料的固化时间少量增加，抗压强度下降明显。体外降解速度及体外释药明显提高，释放的rhBMP-2具有骨诱导活性。[结论]rhBMP-2／PLGA微球／磷酸钙骨水泥新型复合人工骨是具有良好应用前景的骨修复材料。     

乳酸对成骨样细胞成骨表型及碱性磷酸酶基因表达的影响研究

目的 明确聚乳酸降解终产物乳酸对细胞成骨表型和基因表达的影响机理，为聚乳酸支架的精确设计提供参考意义。方法 配制乳酸浓度为8、16、22、27 mmol/L的培养基，将不含乳酸培养基作为对照组，检测培养基的pH和渗透压。利用培养基培养大鼠成骨样细胞Ros17/2.8，观察细胞形态，测定细胞I型胶原、碱性磷酸酶（alkaline phosphatase，ALP）活性和骨钙素含量，盐酸四环素染色钙结节并定量分析。采用实时定量PCR法检测细胞ALP mRNA表达。结果 与对照组相比，随着乳酸浓度增加，培养基pH下降，渗透压升高，成骨样细胞形态改变，数量减少。低浓度乳酸组（8、16 mmol/L）的I型胶原量都显著高于对照组，其余组与对照组相比无显著差异。含乳酸组的细胞ALP活性都低于对照组，并且乳酸浓度越高，细胞ALP活性越低。含乳酸组的骨钙素量与对照组之间没有显著差异。随着乳酸浓度增加，含乳酸组细胞所形成的钙结节阳性面积减少，都低于对照组。低浓度乳酸组（8、16 mmol/L）的细胞ALP mRNA表达量都低于对照组。结论 聚乳酸降解终产物乳酸可抑制细胞ALP mRNA的表达，降低ALP活性。随着乳酸浓度增加，乳酸抑制作用增强，最终降低细胞的成骨矿化能力。此外，乳酸不会抑制细胞分泌I型胶原和骨钙素。     

携载rhBMP-2微球的新型复合人工骨的释药及成骨活性研究

目的 制备一种具有良好降解性和成骨活性，可注射的自凝固新型骨修复材料。方法制备携载rhBMP-2的聚乳酸与聚乙醇酸共聚物（PLGA）微球，并将其与rhBMP-2／磷酸钙骨水泥（CPC）复合。制备出rhBMP-2／PLGA微球／CPC复合人工骨。测定了复合材料释药速度，将复合材料及rhBMP-2-CPC分别植入兔双侧股骨髁骨缺损区域，通过X线、组织学观察比较不同时期材料的降解及成骨情况。结果 复合材料各时间点的体外释药量均大于单纯rhBMP-2／CPC组．与单纯rhBMP-2／CPC材料相比较，复合材料植入体内后不同时间点材料的降解和新骨生成均高于单纯rhBMP-2／CPC植入组。结论 rhBMP-2／PLGA微球的掺入可明显加快rhBMP-2的释放。提高材料的降解速度和成骨活性。     

仿生组装纳米羟基磷灰石/壳聚糖骨修复材料的制备及其生物相容性研究

目的 探讨以一种简单、廉价的方法制备纳米羟基磷灰石/壳聚糖(n-HA/CS)复合材料,并评价其理化特征和生物相容性. 方法采用原位沉析和冷冻干燥法制备n-HA/CS支架,通过扫描电镜、组织切片染色、X线衍射和傅立叶红外光谱分析其微观形貌和组成;采用万能材料试验机分析材料的力学性能.采用材料浸提液和表面接种考察n-HA/CS复合材料对第3代人骨髓基质干细胞(hBMSCs)黏附、增殖的影响,评估其细胞相容性.将n-HA/CS复合材料植入新西兰大白兔背部肌袋,经组织学染色后评价其组织相容性. 结果 n-HA/CS复合材料具有多孔结构,孔隙率为(88.65±2.34)%,孔径为(112.63±20.47) μm,HA晶体颗粒长度为200～700 nm,且分散均匀;X线衍射和红外光谱分析表明合成的HA是含CO32-弱结晶纳米晶体.材料的断裂强度为(1.47±0.15)MPa,弹性模量为(37.52±3.43)kPa,可满足非负重部位骨修复要求.n-HA/CS材料浸提液未明显抑制hBMSCs的增殖,直接接种在n-HA/CS复合材料表面的细胞黏附、增殖功能正常;组织相容性实验也表明,植入4周后组织炎性反应明显减轻,12周后材料基本降解并由新生组织爬行替代. 结论采用原位沉析和冷冻干燥法制备的n-HA/CS复合材料具有良好的理化性质和生物相容性,有望应用于组织工程骨的构建.     

改性壳聚糖基导电复合材料神经导管的体内降解及组织相容性观察

目的 探讨改性壳聚糖基导电复合材料神经导管的体内降解及组织相容性,以期为组织工程神经构建提供新的支架材料.方法 采用微乳液聚合法合成纳米聚吡咯(polypyrrole,PPy),与壳聚糖共混后注入定制的成管模型,冷冻干燥及脱酸后,制成改性纳米PPy/壳聚糖复合材料导管(记作CP导管);再经不同程度乙酰化(乙酰化反应时间...     

羟基磷灰石聚合物载生长因子的研究现状

羟基磷灰石/聚合物复合材料因为仿生细胞外基质，具有优良的生物活性、机械性能、可控降解性能、缓释功能，被广泛应用于骨修复领域。由于生长因子参与骨修复过程，因此羟基磷灰石/聚合物复合材料负载生长因子逐渐成为骨修复领域的研究热点之一。本文综述了近几年国内外羟基磷灰石/聚合物复合材料载生长因子在骨损伤或骨缺损治疗中的研究应用情况，并对其发展前景进行了展望。     

羟基磷灰石晶体纤维增强磷酸钙骨水泥力学性能及生物相容性研究

目的将高长径比的羟基磷灰石(HA)晶体纤维添加入磷酸钙骨水泥(CPC)中,研究HA晶体纤维对CPC抗压力学性能增强的最佳配方及在体内的生物相容性。方法采用水热合成法制备高长径比HA晶体纤维,并验证其细胞毒安全性。将2.5%、5%及10%(wt%)HA晶体纤维添加入CPC中,分析并获取HA晶体纤维对CPC力学性能增强的最佳配方。使用最佳配方制备CPC+HA晶体纤维复合材料,植入大鼠胫骨近端骨缺损模型,4、8周组织学观察HA晶体纤维添加入CPC的成骨性能及生物相容性。对照组为单纯CPC实验组。结果成功制备高长径比HA晶体纤维,其细胞毒安全性为1级(RGR79%)。与对照组相比,2.5%及5%HA晶体纤维添加入CPC可以增强材料的抗压力学性能(P<0.05),其中5%HA晶体纤维对CPC抗压性能的增强效果最佳,10%HA晶体纤维略降低CPC的抗压性能,但无统计学差异(P>0.05)。大鼠体内研究结果显示:与对照组相比,5%HA晶体纤维添加入CPC复合材料植入后材料周围骨体积分数(BV/TV)无显著性差异(P>0.05),HA晶体纤维添加入CPC后材料周围成骨与材料接触好,生物相容性良好。结论水热合成法制备的HA晶体纤维作为添加剂,具有增强CPC抗压力学性能,减低CPC脆性,生物相容性良好的特点,可用作骨植入生物材料的添加剂。     

In vitro studies of composite bone filler based on poly(propylene fumarate) and biphasic α-tricalcium phosphate/hydroxyapatite ceramic powder

While many different filler materials have been applied in vertebral augmentation procedures, none is perfect in all biomechanical and biological characteristics. To minimize possible shortages, we synthesized a new biodegradable, injectable, and premixed composite made from poly(propylene fumarate) (PPF) and biphasic α-tricalcium phosphate (α-TCP)/hydroxyapatite (HAP) ceramics powder and evaluated the material properties of the compound in vitro. We mixed the PPF cross-linked by N-vinyl pyrrolidinone and biphasic α-TCP/HAP powder in different ratios with benzoyl peroxide as an initiator. The setting time and temperature were recorded, although they could be manipulated by modulating the concentrations of hydroquinone and N,N-dimethyl-p-toluidine. Degradation, cytocompatibility, mechanical properties, and radiopacity were analyzed after the composites were cured by a cylindrical shape. We also compared the study materials with poly(methyl methacrylate) (PMMA) and PPF with pure HAP particles. Results showed that lower temperature during curing process (38-44°C), sufficient initial mechanical compressive fracture strength (61.1±3.7MPa), and gradual degradation were observed in the newly developed bone filler. Radiopacity in Hounsfield units was similar to PMMA as determined by computed tomography scan. Both pH value variation and cytotoxicity were within biological tolerable limits based on the biocompatibility tests. Mixtures with 70% α-TCP/HAP powder were superior to other groups. This study indicated that a composite of PPF and biphasic α-TCP/HAP powder is a promising, premixed, injectable biodegradable filler and that a mixture containing 70% α-TCP/HAP exhibits the best properties.     

Polyanhydride copolymer and bioceramic composites as bone substitutes

Background/PurposeDurable mechanical strength and biocompatibility are the two major requirements for osteogenic scaffolds. Polyanhydrides are a class of biodegradable polymers characterized by anhydride bonds that connect repeating units of the polymer backbone chain. Hydroxyapatite (HAP) is the main component of human bone and is a good osteoinductive factor that promotes bone mineralization. This work validates the combination of polyanhydrides and HAP for biomedical application.MethodsPolyanhydride copolymers were fabricated from sebacic acid (SA) and 1,6-bis(p-carboxyphenoxy)hexane (CPH). HAP was surface-modified by polycaprolactone (PCL), and testing tablets were made using different ratios of copolymers and surface-grafted HAP (g-HAP). Degradation tests were performed to evaluate mechanical strength, pH, and weight loss. Biocompatibility was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and live/dead stain test. Cell affinity was measured using scanning electronic microscopy (SEM).ResultsThe favorable surface erosion property of polyanhydrides prevented marked changes in the mechanical properties over time. In addition, the degradation byproducts of the copolymer did not cause a serious decline in pH and were less harmful to the cells. g-HAP increased cell affinity for the polymer surface.ConclusionThe research team synthesized polyanhydride/g-HAP composites with high mechanical strength, slow degradation, and excellent biocompatibility. The result showed that a CPH/SA ratio of 7:3 in combination with 10 wt% g-HAP was optimal as bone substitute.     

Composites of Calcium Phosphate and Polymers as Bone Substitution Materials

Abstract The state of the art of calcium phosphate/polymer composites for bone substitution is reviewed. Many combinations are possible which were proposed to improve the mechanical properties and the biocompatibility. However, the way from the laboratory to the clinical application is long, and potential candidates for new bone substitution materials have to meet many different requirements.     

髋关节假体材料的分类及应用进展

关节假体材料的选择关系着人工关节置换的成败,目前临床中使用的髋关节假体材料主要有金属、陶瓷、高分子复合材料及碳质材料等,虽在生物相容性、弹性模量、力学性能、使用期限等方面都有不同程度的进步,但与理想人工关节设计标准仍有较大差距。本文主要从髋关节假体材料的分类出发,对比分析各类髋关节假体材料优缺点,旨在为临床合理选择髋关节假体和提高材料性能提供参考。并认为高分子复合材料虽在耐磨性方面尚有不足,在生物相容性、力学性能、耐腐蚀性、价格等综合方面比其他材料更具优越性。目前对该材料研究也主要在耐磨性、关节面磨屑问题、强度等方面,发展迅速,性能提升快,具有广阔的发展前景。     

A biodegradable antibiotic delivery system based on poly-(trimethylene carbonate) for the treatment of osteomyelitis

Background and purpose Many investigations on biodegradable materials acting as an antibiotic carrier for local drug delivery are based on poly(lactide). However, the use of poly(lactide) implants in bone has been disputed because of poor bone regeneration at the site of implantation. Poly(trimethylene carbonate) (PTMC) is an enzymatically degradable polymer that does not produce acidic degradation products. We explored the suitability of PTMC as an antibiotic releasing polymer for the local treatment of osteomyelitis.Methods This study addressed 2 separate attributes of PTMC: (1) the release kinetics of gentamicin-loaded PTMC and (2) its behavior in inhibiting biofilm formation. Both of these characteristics were compared with those of commercially available gentamicin-loaded poly(methylmethacrylate) (PMMA) beads, which are commonly used in the local treatment of osteomyelitis.Results In a lipase solution that mimics the in vivo situation, PTMC discs with gentamicin incorporated were degraded by surface erosion and released 60% of the gentamicin within 14 days. This is similar to the gentamicin release from clinically used PMMA beads. Moreover, biofilm formation by Staphylococcus aureus was inhibited by approximately 80% over at least 14 days in the presence of gentamicin-loaded PTMC discs. This is similar to the effect of gentamicin-loaded PMMA beads. In the absence of the lipase, surface erosion of PTMC discs did not occur and gentamicin release and biofilm inhibition were limited.Interpretation Since gentamicin-loaded PTMC discs show antibiotic release characteristics and biofilm inhibition characteristics similar to those of gentamicin-loaded PMMA beads, PTMC appears to be a promising biodegradable carrier in the local treatment of osteomyelitis.     

Single walled carbon nanotube composites for bone tissue engineering

The purpose of this study was to develop single walled carbon nanotubes (SWCNT) and poly lactic‐co‐glycolic acid (PLAGA) composites for orthopedic applications and to evaluate the interaction of human stem cells (hBMSCs) and osteoblasts (MC3T3‐E1 cells) via cell growth, proliferation, gene expression, extracellular matrix production and mineralization. PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40, and 100 mg), characterized and degradation studies were performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Imaging studies revealed that MC3T3‐E1 and hBMSCs cells exhibited normal, non‐stressed morphology on the composites and all were biocompatible. Composites with 10 mg SWCNT resulted in highest rate of cell proliferation (p < 0.05) among all composites. Gene expression of alkaline phosphatase, collagen I, osteocalcin, osteopontin, Runx‐2, and Bone Sialoprotein was observed on all composites. In conclusion, SWCNT/PLAGA composites imparted beneficial cellular growth capabilities and gene expression, and mineralization abilities were well established. These results demonstrate the potential of SWCNT/PLAGA composites for musculoskeletal regeneration and bone tissue engineering (BTE) and are promising for orthopedic applications. © 2013 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 31:1374–1381, 2013     

Bioabsorbable screw fixation for the treatment of ankle fractures

Background Self-reinforced poly(l/dl)lactide 70:30 (SR-PLA70) retains its strength in bone for 24 weeks, whereas self-reinforced poly-l-lactide (SR-PLLA) retains its strength for over 36 weeks. In this prospective randomized study, bioabsorbable 4.5-mm SR-PLA70 screws were compared with SR-PLLA screws in the treatment of displaced ankle fractures in adults. Methods Sixty-two patients with ankle fractures needing operative treatment were randomized into two groups. Comminuted fractures needing plating were excluded. In total 54 of 62 patients were followed up for 1 year by clinical evaluation, radiographs, and Olerud-Molander score. Results The study groups differed significantly only in the mean duration of sick leave (SR-PLA70, 60 days; SR-PLLA, 65 days; P = 0.02). At the 1-year follow-up, syndesmotic ossification was more common in the SR-PLA70 group (5 versus 1 patient, not significant). Radiologically, the screw channel had not disappeared in any of the patients by the 1-year follow-up. Conclusions Both implant types proved to have good biocompatibility. SR-PLA70 and SR-PLLA screws are suitable in selected cases for the fixation of ankle fractures, but the mechanical stability of the fixation has to be carefully monitored perioperatively.     

Fixation of distal femoral osteotomies with self-reinforced poly(desamino tyrosyl–tyrosine ethyl ester carbonate) rods: an experimental study on rats

 Self-reinforced poly(desamino tyrosyl–tyrosine ethyl ester carbonate) poly(DTE carbonate) rods (diameter, 2 mm; length, 26 mm) were implanted into the dorsal subcutaneous tissue of 16 rats. Osteotomies of the distal femur were fixed with these rods (2 mm by 15 mm) in 64 other rats. The follow-up times varied from 1 week to 1 year. After sacrifice, three-point bending and shear tests and molecular weight measurements were performed for subcutaneously placed rods. Radiological, histological, histomorphometrical, microradiographic, and oxytetracycline-fluorescence studies of the osteotomized and intact control femurs were performed. At 36 weeks, the bending strength of the rods was nearly at the same level as the initial value, and the shear strength was decreased to about one quarter of the initial value. One of the 64 evaluated osteotomies showed signs of infection at 24 weeks, and there were five failures of fixation. Fifty-eight osteotomies healed uneventfully. No gross signs of inflammatory or foreign-body reactions were observed. The present investigation showed that the mechanical strength and fixation properties of SR-poly(DTE carbonate) rods are suitable for fixation of cancellous bone osteotomies in rats. The present article is the first report on successful application of SR-poly(DTE carbonate) rods for fixation of cancellous bone osteotomies. Received: September 25, 2001 / Accepted: May 7, 2002     

Spinal Antinociceptive Action of an N-Type Voltage-dependent Calcium Channel Blocker and the Synergistic Interaction with Morphine

Background: Four different voltage-dependent calcium channels (L-, N-, T-, and P-types) are distinguished in the central nervous system. Both L- and N-type calcium channels have been implicated in the release of neurotransmitters from sensory neurons in the spinal cord. It has been demonstrated that intrathecal L-type calcium channel blockers, which alone do not exhibit any antinociceptive effects, potentiate the antinociceptive effects of intrathecal morphine. The current study was designed to investigate the antinociceptive effects of the intrathecally administered N-type calcium channel blocker, omega-conotoxin GVIA (omega-CgTx). The interaction between morphine and omega-CgTx at the level of the spinal cord also was examined.

Methods: In male Sprague-Dawley rats, lumbar intrathecal catheters were chronically implanted. Tail flick and mechanical paw pressure tests were used to assess thermal and mechanical nociceptive thresholds, respectively. Morphine, omega-CgTx, or a combination of morphine and omega-CgTx was administered intrathecally, and the nociceptive thresholds were determined. Isobolographic analyses were used to define the nature of the functional interactions between morphine and omega-CgTx.

Results: Intrathecal omega-CgTx produced antinociception in a dose- and time-dependent manner. Isobolographic analyses revealed that intrathecal omega-CgTx and morphine interacted synergistically in both nociceptive tests.