复合壳聚糖微球-丝素基载药α-磷酸三钙骨水泥的细胞相容性及毒性

背景:磷酸钙骨水泥具有良好的生物相容性和骨传导性,已被应用于临床,但其不良的力学性能和缺乏骨诱导性限制了其进一步发展和应用。目的:制备壳聚糖微球-丝素基载药α-磷酸三钙骨水泥,验证其细胞相容性及细胞毒性。方法:分别以含体积分数10%胎牛血清和1%双抗的α-MEM培养基、苯酚、100%及50%复合壳聚糖微球-丝素基载药α-磷酸三钙骨水泥材料的浸提液培养MC3T3-E1细胞,采用MTT法评估细胞生长增殖情况,采用乳酸脱氢酶活性检测法判断复合壳聚糖微球-丝素基载药α-磷酸三钙骨水泥材料的毒性。将MC3T3-E1细胞系与复合壳聚糖微球-丝素基载药α-磷酸三钙骨水泥材料共培养,扫描电镜观察细胞在材料表面的附着及生长。结果与结论:复合壳聚糖微球-丝素基载药α-磷酸三钙骨水泥材料浸提液对MC3T3-E1细胞的生长增殖无明显影响,无明显细胞毒性。MC3T3-E1细胞在复合壳聚糖微球-丝素基载药α-磷酸三钙骨水泥材料表面生长良好,伸展充分,在材料表面伸出伪足,与材料贴附紧密,表明壳聚糖微球-丝素基载药α-磷酸三钙骨水泥细胞相容性良好。     

可注射性UPPE/β-TCP复合材料的制备及其细胞相容性实验研究

目的：探讨可注射性UPPE／β-TCP（不饱和聚磷酸酯邝一磷酸钙）复合材料的制备及其细胞生物相容性。方法：制备UPPE／β-TCP复合材料并测量其理化性质；原代培养小鼠骨髓基质细胞（MSCs），采用浸提法制备UPPE／β-TCP培养基浸提液，用MTr法测定细胞增值率并进行细胞毒性分级；将MSCs与复合材料混合培养并用扫描电镜观察。结果：UPPE／β-TCP复合材料的最大压缩强度和压缩模量分别为94．36±6．96MPa、2096．93±92．86MPa，水接触角为27°；培养的细胞大量增殖，细胞形态良好，UPPE／β—TCP复合材料的毒性分级为0级或者1级，通过扫描电镜观察MSCs与复合材料混合培养的情况，发现MSCs可以黏附生长。结论：制备的可注射性UPPE／β-TCP复合材料有良好的理化性质；体外生物相容性良好。     

新型大孔隙磷酸钙骨水泥作为骨组织工程支架的相关研究

目的 探讨新型大孔隙磷酸钙骨水泥(CPC)材料支架的细胞毒性和对细胞黏附、生长和增殖的影响.方法 通过添加甘露醇制孔剂和应用磷酸钠溶液作为CPC固化液的方法合成新型CPC材料.通过CCK8法检测细胞在新型CPC材料浸提液中的生长增殖情况;通过电子扫描电镜测试材料孔径和细胞在材料表面上黏附生长情况;应用力学三点弯曲实验测试新型CPC的生物力学性能.结果 新型CPC材料的孔径值达到(267.43±118.01)μm,孔隙率为(66.15±6.91)％.新型CPC材料的最大负荷、抗弯强度和坚韧度较传统CPC均增加了约1倍(P＜0.05).新型CPC材料浸提液与细胞共培养2、4、6、8d后CCK8法测试吸光度(OD)值与阴性对照组比较其差异无统计学意义(P＞0.05).结论 新型CPC材料具有强大的生物力学性能、大孔隙、高孔隙率和良好的生物相容性,有望成为理想的骨组织工程支架.     

rhBMP-2/聚乳酸与聚乙醇酸共聚物载药微球的制备及成骨活性研究

目的制备一种具有良好降解性和成骨活性可注射的rhBMP-2载体材料。方法采用复乳-溶剂蒸发技术制备携载rhBMP-2的聚乳酸与聚乙醇酸共聚物P(LGA)微球。测定材料的制备参数及其特性,包括材料的形貌、载药率、释药速度,并将载药微球植入鼠股部肌袋,通过X线、组织学评价载体材料的异位成骨能力。结果载药微球粒径为(253±64)μm,载药率0.52%±0.14%,载药微球rhBMP-2体外释放24h时为15.2%±0.8%,随后呈持续缓慢释放,28d时总计达48.6%±5.3%。载药微球植入鼠股部肌袋4周,材料周围有明显的骨形成。结论载有rhBMP-2的PLGA微球具有良好的缓释效果和生物活性,是一种较为理想的生长因子载体材料和释放系统。     

rhBMP-2／无定形磷酸钙纳米缓释微粒成骨活性的实验研究

目的探讨无定形磷酸钙（ACP）对rhBMP-2的缓释作用，检测rhBMP-2／ACP纳米缓释微粒的成骨活性。方法用扫描电镜观察已制备rhBMP-2／ACP缓释微粒的大小、形态：测定rhBMP-2的体外释放情况并描绘曲线；用MTT法检测缓释微粒对兔骨髓间充质干细胞（MSC）增殖情况的影响：用碱性磷酸酶（ALP）试剂盒检测细胞ALP活性以反映缓释微粒对其分化的影响．并与ACP的作用进行比较；将缓释微粒植入大鼠股部肌袋．通过X线、组织形态学观察评价缓释微粒的异位成骨能力。结果缓释微粒大小为100nm左右．具有典型的无定形球形面貌。开始时为快速释放期．随后呈缓慢持续释放。缓释微粒能显著促进MSC的增殖和分化，植入大鼠股部肌袋12周．材料大部分降解．有明显的骨形成。结论ACP可作为rhBMP-2合适的缓释载体材料．生成的纳米缓释微粒具有良好的降解性能和成骨活性。     

rhBMP-2／PLGA缓释支架的制备及对MSCs细胞成骨活性的体外研究

目的探讨骨形态发生蛋白（rhBMP-2）的聚乳酸聚乙醇酸共聚物（PLGA）体外缓释生物支架对人骨髓间充质干细胞（MSCs）细胞的影响。方法采用粒子沥滤-冷冻干燥复合工艺制备了附载rhBMP-2的PLGA生物支架,并检测了在PLGA的降解过程中rhBMP-2的释药规律;同时分离培养人骨髓间充质干细胞,体外培养后分别接种于附载和未附载rhBMP-2的PLGA支架上。扫描电镜观察不同时间段MSC在支架上的生长情况;MTT法测定细胞增殖情况。结果rhBMP-2能被包裹进PLGA支架中,而且可以在PLGA支架降解过程中持续释放出来并诱导骨发生。结论骨形态发生蛋白的PLGA复合载体是一种较为理想的新型生物支架。     

微球在磷酸钙骨水泥中的应用

磷酸钙骨水泥(CPC)因具有良好的生物活性和生物相容性,目前已成功应用于临床。磷酸钙骨水泥从制备到应用避免了高温烧结的过程,是各类药物和高分子材料的优良载体。本文综述了近年来微球以及各类载药微球与磷酸钙骨水泥相结合的应用,主要从药物缓释、快速降解、形成多孔支架以及改善力学性能这几个方面论述了微球在磷酸钙骨水泥临床应用中的作用。本文通过分析总结微球改善磷酸钙骨水泥性能的原理及方法,为今后进一步改进、制备符合临床使用要求的理想型磷酸钙骨水泥奠定了理论基础。     

新型可注射可降解磷酸钙骨水泥的生物相容性

背景：体外实验已证实新型磷酸钙骨水泥有良好的可注射性、力学性能、抗溃散性及体外降解性能。 目的：验证新型可注射、可降解磷酸钙骨水泥的生物相容性。 方法：①急性毒性实验：分别向昆明小鼠尾静脉可注射新型磷酸钙骨水泥浸提液与生理盐水。②热源实验：在新西兰兔耳缘静脉注射新型磷酸钙骨水泥浸提液。③溶血实验：在兔抗凝血分别加入新型磷酸钙骨水泥浸提液、生理盐水及双蒸水。④迟发型超敏反应实验：在豚鼠肩胛骨内侧部位分别注射可注射新型磷酸钙骨水泥浸提液与生理盐水,并进行敷贴激发实验。⑤体外细胞毒性实验：在L929系小鼠成纤维细胞株培养液中分别加入可注射新型磷酸钙骨水泥浸提液、聚乙烯浸提液及苯酚溶液。⑥微核实验：分别在昆明小鼠腹腔注射可注射新型磷酸钙骨水泥浸提液、生理盐水与环磷酰胺。⑦肌肉植入实验：将新型磷酸钙骨水泥植入新西兰兔脊柱两侧肌肉内。 结果与结论：新型可注射磷酸钙骨水泥无毒,无刺激性及致敏性,无热源反应,具有良好的血液相容性,植入动物肌肉后为非组织刺激物,具有良好的生物相容性,因而具有较好的生物安全性。     

纤维蛋白胶复合重组人骨形态发生蛋白2微球对犬骨髓基质细胞增殖与分化的影响

背景：前期实验证实聚乳酸-聚乙醇酸微球/纤维蛋白胶能作为重组人骨形态发生蛋白2的良好可注射性缓释载体。 目的：观察可注射性骨形态发生蛋白缓释体系对犬骨髓基质细胞增殖与分化的影响。 方法：采用复乳-溶剂挥发法制备重组人骨形态发生蛋白2/聚乳酸-聚乙醇酸共聚物载药微球,然后将微球与纤维蛋白胶复合制备出重组人骨形态发生蛋白2/聚乳酸-聚乙醇酸共聚物/纤维蛋白胶复合材料,采用细胞培养及组织化学等方法观察微球对犬骨髓基质细胞的增殖与分化的影响。 结果与结论：重组人骨形态发生蛋白2/聚乳酸-聚乙醇酸共聚物/纤维蛋白胶微球对骨髓基质细胞的增殖无明显影响,但对细胞的分化功能有明显的促进作用。说明纤维蛋白胶复合重组人骨形态发生蛋白2微球能够提高骨髓基质细胞的体外成骨能力,可作为骨形态发生蛋白的良好载体。     

新型聚己内酯/磷酸钙支架的制备及生物相容性研究

探讨新型聚己内酯(PCL)/磷酸钙(CPC)复合材料支架的制备方法及对骨髓基质细胞(BMSCs)的生物相容性。采用溶液共混法,利用可溶盐晶体做造孔剂,制备PCL/CPC复合材料支架,以单纯PCL和CPC支架为对照组,Q800型动态力学分析仪进行动态力学性能试验(DMA),采用排水法测量孔隙率;灭菌后通过与犬BMSCs体外共同培养后细胞形态、生长曲线、碱性磷酸酶(ALP)染色和半定量及骨钙素(OC)半定量等方法检测细胞在支架材料上的黏附、增殖及成骨分化情况,动物体内异位成骨检测其成骨情况。结果显示,复合材料的储能模量在PCL/CPC比例为7:3时达到最大,制得的材料孔径为250～350μm,多孔支架的孔隙率为70%～80%;BMSCs在新型PCL/CPC组、CPC组支架表面分布均匀,生长增殖明显较PCL组活跃(P<0.05);PCL/CPC组、CPC组BMSCs成骨行为与PCL组之间有显著差异(P<0.05)。动物体内异位成骨检测提示,4周时PCL/CPC组为13.78%±1.60%、CPC组BMSCs为15.29%±1.20%,成骨显著强于PCL组BMSCs的7.56%±2.20%(P<0.05),表明PCL和CPC的复合明显改善了两种材料的缺陷,获得的PCL/CPC支架具有良好的生物相容性,可与BMSCs共同构建具有成骨能力的三维立体组织工程化骨。     

仿生活性人工软骨的体外构建及其异位成软骨分化实验研究

应用先进快速成形技术(RP)制备32枚粒度均匀(尺寸均为4mm×4mm×4mm)的聚乳酸-聚羟乙酸(PLGA)人工载体,该载体经I型胶原表面修饰后均分为A、B两组。A组载体复合人骨形态发生蛋白-2基因转染(rAAV-hBM P-2)的兔骨髓基质细胞(M SC s,2×104个细胞/枚);B组每枚载体复合等量、同代次、未基因转染M SC s。体外培养第5 d,从两组各取12枚细胞-载体复合物植入裸鼠皮下,术后30 d取材观察。结果发现rAAV-hBM P-2转染的M SC s成功表达目的基因。RP制备的PLGA载体具有良好的空间结构,大孔及材料表面微孔孔径分别为300μm和3~5μm。体外培养3~5 d,两组载体均复合生长着大量种子细胞。皮下埋植30 d,A组植入物形成较为典型的软骨细胞及基质,II型胶原蛋白表达阳性;同期B组植入物无软骨组织形成。A组聚酯材料面积百分率显著低于B组(P<0.01)。结果表明RP结合载体材料表面修饰,能制备出兼具理想孔隙结构和良好生物相容性的组织工程支架载体,该载体高效复合rAAV-hBM P-2转染的M SC s为组织工程软骨构建创造有利条件。     

An injectable,biodegradable calcium phosphate cement containing poly lactic-co-glycolic acid as a bone substitute in ex vivo human vertebral compression fracture and rabbit bone defect models

Purpose/Aim of the study: To evaluate the biomechanical characteristics and biocompatibility of an injectable, biodegradable calcium phosphate cement (CPC) containing poly lactic-co-glycolic acid (PLGA). Materials and methods: A vertebral compression fracture model was established using 20 human cadaveric vertebrae (T11-L3) divided into CPC/PLGA composite versus PMMA groups for biomechanical testing. In addition, 35 New Zealand rabbits were used to evaluate biodegradability and osteoconductive properties of CPC/PLGA using a bone defect model. In vitro cytotoxicity was evaluated by culturing with L929 cells. Results: The CPC/PLGA composite effectively restored vertebral biomechanical properties. Compared with controls, the maximum load and compression strength of the CPC/PLGA group were lower, and stiffness was lower after kyphoplasty (all p <.05). Degradation was much slower in the control CPC compared with CPC/PLGA group. The bone tissue percentage in the CPC/PLGA group (44.9 ± 23.7%) was significantly higher compared with control CPC group (25.7 ± 10.9%) (p <.05). The viability of cells cultured on CPC/PLGA was greater than 70% compared with the blanks. Conclusions: Our biodegradable CPC/PLGA composite showed good biomechanical properties, cytocompatibility, and osteoconductivity and may represent an ideal bone substitute for future applications.     

Bone regeneration using photocrosslinked hydrogel incorporating rhBMP-2 loaded 2-N, 6-O-sulfated chitosan nanoparticles

Although rhBMP-2 has excellent ability to accelerate the repair of normal bone defects, limitations of its application exist in the high cost and potential side effects. This study aimed to develop a composite photopolymerisable hydrogel incorporating rhBMP-2 loaded 2-N, 6-O-sulfated chitosan nanoparticles (PH/rhBMP-2/NPs) as the bone substitute to realize segmental bone defect repair at a low growth factor dose. Firstly rhBMP-2 loaded 2-N, 6-O-sulfated chitosan nanoparticles (rhBMP-2/NPs) were prepared and characterized by DLS and TEM. Composite materials, PH/rhBMP-2/NPs were developed and investigated by SEM-EDS as well as a series of physical characterizations. Using hMSCs as an in vitro cell model, composite photopolymerisable hydrogels incorporating NPs (PH/NPs) showed good cell viability, cell adhesion and time dependent cell ingrowth. In vitro release kinetics of rhBMP-2 showed a significantly lower initial burst release from the composite system compared with the growth factor-loaded particles alone or encapsulated directly within the hydrogel, followed by a slow release over time. The bioactivity of released rhBMP-2 was validated by alkaline phosphatase (ALP) activity as well as a mineralization assay. In in vivo studies, the PH/rhBMP-2/NPs induced ectopic bone formation in the mouse thigh. In addition, we further investigated the in vivo effects of rhBMP-2-loaded scaffolds in a rabbit radius critical defect by three dimensional micro-computed tomographic (μCT) imaging, histological analysis, and biomechanical measurements. Animals implanted with the composite hydrogel containing rhBMP-2-loaded nanoparticles underwent gradual resorption with more pronounced replacement by new bone and induced reunion of the bone marrow cavity at 12 weeks, compared with animals implanted with hydrogel encapsulated growth factors alone. These data provided strong evidence that the composite PH/rhBMP-2/NPs are a promising substitute for bone tissue engineering.     

RhBMP-2 microspheres-loaded chitosan/collagen scaffold enhanced osseointegration: an experiment in dog

The purpose of this study is to develop a novel recombinant human bone morphogenetic protein-2 (rhBMP-2) sustained release scaffold for dental implant osseointegration, and to evaluate the effect of this scaffold on promoting bone formation. RhBMP-2 was encapsulated in the poly-D,L-lactide-co-glycolide (PLGA) biodegradable microspheres, which were subsequently dispersed in a chitosan/collagen composite scaffold. This rhBMP-2 microspheres-loaded scaffold (S-MB) was compared with a chitosan/collagen scaffold without microspheres that directly encapsulated rhBMP-2 (S-B) in vitro and in vivo. The microstructure of the new scaffold was examined with scanning electron microscopy. The release profile of rhBMP-2 in vitro was measured at interval periods. The effect of rhBMP-2 encapsulated scaffolds on enhancing bone formation through implantation in dogs' mandibles was identified by histological examination of the regenerated bone after 4 weeks of implantation. Due to PLGA microspheres being loaded, the S-MB exhibited lower values at porosity and swelling rate, as well as a higher effective release dose than that of the S-B. Bone density, bone-implant contact, and bone-fill values measured from dog experiments demonstrated that the S-MB induced bone regeneration more quickly and was timely substituted by new bone. It was concluded that this sustained carrier scaffold based on microspheres was more effective to induce implant osseointegration.     

Retention and activity of BMP-2 in hyaluronic acid-based scaffolds in vitro.

Bone morphogenetic protein-2 (BMP-2) delivered in a suitable implantable matrix has the potential to repair local skeletal defects by inducing new bone formation from undifferentiated pluripotent stem cells resident in host tissue. In this study, we examined in vitro the potential of a derivatized hyaluronic acid (Hyaff-11) scaffold as a delivery vehicle for recombinant human BMP-2 (rhBMP-2) in bone and cartilage repair therapies. Hyaff-11 scaffolds were fabricated using a phase inversion/particulate leaching method and soak-loaded with rhBMP-2. In vitro release kinetics of rhBMP-2, demonstrated using enzyme-linked immunosorbant assay and alkaline phosphatase (ALP) assay revealed a slow, sustained rhBMP-2 release during 28 days, with a cumulative release of 31.82% of the initial rhBMP-2 loaded. rhBMP-2 was released in bioactive form as demonstrated by ALP induction of pluripotent cell line, C3H10T1/2 (T1/2), down the osteoblast lineage when incubated with the release supernatants. rhBMP-2 retention in Hyaff-11 scaffolds was greater than that from collagen gels, which released most of the initially loaded rhBMP-2 by 14 days. rhBMP-2-loaded Hyaff-11 scaffolds were also seeded with T1/2 cells and evaluated at 3, 7, 14, and 28 days for viability and expression of osteoblast phenotype. Cells remained viable throughout the study and expressed a time- and dose-dependent ALP and osteocalcin expression in the rhBMP-2 groups. Based on these observations, Hyaff-11 scaffolds may be suitable delivery systems for rhBMP-2 in bone/cartilage repair because of their ability to retain rhBMP-2, release low levels of bioactive rhBMP-2 to the local environment in a sustained manner, and stimulate differentiation of pluripotent stem cells.     

Improving bone formation in a rat femur segmental defect by controlling bone morphogenetic protein-2 release

Nonunion is a common complication in open fractures and other severe bone injuries. Recombinant human bone morphogenetic protein-2 (rhBMP-2) delivered on a collagen sponge enhances healing of fractures. However, the burst release of rhBMP-2 necessitates supra-physiological doses of rhBMP-2 to achieve a robust osteogenic effect, which introduces risk of ectopic bone formation and severe inflammation and increases the cost. Although the concept that the ideal pharmacokinetics for rhBMP-2 includes both a burst and sustained release is generally accepted, investigations into the effects of the release kinetics on new bone formation are limited. In the present study, biodegradable polyurethane (PUR) and PUR/microsphere [PUR/poly(lactic-co-glycolic acid)] composite scaffolds with varying rhBMP-2 release kinetics were compared to the collagen sponge delivery system in a critical-sized rat segmental defect model. Microcomputed tomography analysis indicated that a burst followed by a sustained release of rhBMP-2 from the PUR scaffolds regenerated 50% more new bone than the collagen sponge loaded with rhBMP-2, whereas a sustained release without the burst did not form significantly more bone than the scaffold without rhBMP-2. This study demonstrated that the putative optimal release profile (i.e., burst followed by sustained release) for rhBMP-2 can be achieved using PUR scaffolds, and that this enhanced pharmacokinetics regenerated more bone than the clinically available standard of care in a critical-sized defect in rat femora.     

RhBMP-2-loaded Poly(lactic-co-glycolic acid) microspheres fabricated by coaxial electrospraying for protein delivery

In this study, we fabricated recombinant human bone morphogenetic protein-2 (rhBMP-2) loaded Poly(lactic-co-glycolic acid) (PLGA) microspheres with core–shell structures and particle sizes ranging from 2.5 to 8 μm by coaxial electrospraying. The manufacturing process of core–shell microspheres by coaxial electrospraying is simpler than that with other methods, and a smaller diameter can be obtained. The microspheres were analyzed by environmental scanning electron microscopy, transmission electron microscopy (TEM), and laser scanning confocal microscopy (LSCM). Moreover, the drug release profiles and degradation of rhBMP-2-loaded PLGA microspheres in vitro were investigated for 21 days and for 7 weeks, respectively. The rhBMP-2 was stabilized by using bovine serum albumin (BSA) to ensure protein activity in the electrospraying process. Fluorescently labeled protein that was loaded into the core–shell PLGA microspheres was verified by LSCM. The distinct layered structure that existed in the manufactured core–shell microspheres can be observed by TEM. Cell Counting Kit-8 (CCK-8) indicated that the core–shell PLGA microspheres loaded with rhBMP-2 have great potential for the treatment of bone defects, for bone regeneration, and in bone tissue engineering.