电活性可生物降解纳米复合材料PAP/op-HA/PLGA的制备及成骨活性

以苯胺五聚体与聚乳酸（PLA）的三嵌段共聚物（PAP）与表面接枝低聚乳酸的纳米羟基磷灰石（op-HA）和聚丙交酯-乙交酯（PLGA）的复合物共混,制备的电活性可降解纳米复合材料PAP/op-HA/PLGA为研究对象,采用紫外可见光谱、循环伏安扫描和标准四探针法分析其电化学特性及电导率。ESEM观察其膜表面形貌,接触角评价其亲水性。通过在材料膜表面接种兔成骨细胞进行体外培养,采用荧光染色、NIH Image J图像分析和Real-time PCR综合评价细胞在材料表面的粘附、扩展（细胞面积比）和成骨相关基因的表达水平,以此评价新型电活性纳米复合骨修复材料PAP/op-HA/PLGA的表面性质和生物活性。结果表明,PAP/op-HA/PLGA的电导率较低（~5?10?6 S/cm）但具有良好的电化学氧化还原性能,PAP含量为0.1%时材料的亲水性明显改善,成骨细胞的粘附和扩展明显增强。培养7天时骨形态蛋白- 2（BMP-2）和骨连接蛋白（Osteonectin）的基因表达水平明显提高,而对Ⅰ型胶原蛋白的基因表达没有明显影响。提示PAP/op-HA/PLGA具有良好的细胞相容性和成骨活性。     

聚羟基脂肪酸酯的亲水性改性及其与人脐静脉内皮细胞相容性的研究

用丝素蛋白(SF)对微生物合成的高分子聚合物聚(3-羟基丁酸酯-co-3-羟基己酸酯)(PHBHHx)进行亲水改性,以提高材料的生物相容性.水接触角测定和表面自由能分析表明,丝素蛋白在支架表面吸附,使PHBHHx材料表面的水接触角从90°降至51°,表面自由能从37.9 mJ/m2增至57.4 mJ/m2,因而增加了材料的亲水性.进一步对亲水性改性前后PHBHHx多孔支架与人脐静脉内皮细胞(HUVECs)的相容性进行了比较.MTT法细胞活力分析表明,细胞在支架上培养3,5,7天后,其在SF改性PHBHHx多孔支架上的活力显著高于在未改性的PHBHHx支架上的活力;扫描电镜观察细胞生长形貌表明,细胞在改性后多孔支架上黏附及生长5天后,形成了连续细胞单层,其生长状态优于在未改性的PHBHHx支架上的生长状态;胶原含量测定表明细胞在改性后支架上比在未改性支架上有更好的胶原分泌能力,即改性后支架更利于诱导HUVECs分泌细胞外基质(ECM)从而构建类似体内的生长环境.     

改性纳米羟基磷灰石/PLGA复合材料的制备及生物活性

以低聚乳酸接枝改性的羟基磷灰石纳米粒子(op-HA)和聚丙交酯-乙交酯(PLGA)制备的生物可降解纳米复合材料(op-HA/PLGA)为研究对象, 采用FTIR, TGA, ESEM和EDX分析其接枝反应、接枝率、表面形貌和钙磷沉积情况, 通过在材料膜表面接种兔成骨细胞进行体外培养, 采用荧光染色、NIH Image J图像分析和Real-time PCR综合评价细胞在材料表面的形态、黏附面积比、增殖能力和基因表达水平, 以此评价新型骨修复纳米复合材料op-HA/PLGA的表面性质和生物活性. 研究结果表明, op-HA的表面接枝率为8.3%, 掺入至PLGA后可形成富含钙磷的粗糙表面, 促进成骨细胞的黏附、扩展和增殖, 提高Ⅰ型胶原蛋白(Collagen-Ⅰ)、骨形态蛋白-2(BMP-2)和骨连接蛋白(Osteonectin)的基因表达水平, 提高材料的钙磷沉积能力. op-HA/PLGA具有良好的细胞相容性和成骨活性.     

稀土化合物TbCl3对成骨细胞系MC3T3-E1增殖、分化和矿化功能的影响

在细胞和分子水平上,研究了稀土化合物氯化铽(TbCl_3)对成骨细胞MC3T3-E1增殖、分化及矿化功能的影响。结果表明,细胞水平上,浓度为0.000 1、0.001、0.01、0.1、1和10μmol·L-1的TbCl_3均促进MC3T3-E1细胞的增殖、分化及其矿化功能,然而,当浓度升至为100和1 000μmol·L-1时,TbCl_3表现出抑制作用。分子水平上,浓度为0.000 1和0.1μmol·L-1的TbCl_3明显上调成骨分化相关基因骨形成蛋白2(BMP-2),碱性磷酸酶(ALP),骨涎蛋白(BSP),Ⅰ型胶原蛋白(ColⅠ),骨钙素(OCN)和runt相关转录因子2(Runx2)的表达。浓度为1 000μmol·L-1的TbCl_3则抑制上述成骨分化相关基因的表达。浓度为0.000 1、0.1和1μmol·L-1的TbCl_3促进成骨分化相关蛋白Runx2,BMP-2和OCN的表达;结果显示,低浓度的TbCl_3促进MC3T3-E1细胞的成骨分化及矿化功能,而高浓度TbCl_3则呈现出抑制作用。TbCl_3通过调控Runx2的表达刺激早期成骨分化相关基因BMP-2、ColⅠ和晚期成骨分化相关基因ALP、OCN的表达,从而诱导MC3T3-E1成骨分化。     

3D打印nHA/PEEK-AgNPs复合多孔支架的制备与性能

通过熔融沉积成型3D(FDM 3D)打印技术进行打印，制备成nHA/PEEK复合多孔支架。再采用多巴胺氧化聚合和硝酸银化学还原法，在支架表面形成银纳米颗粒涂层，从而制备出nHA/PEEK-AgNPs复合多孔支架。nHA/PEEK-AgNPs具有独特的三维多孔结构，表面接触角约为(33.2±3.65)(°)，展示出较好的亲水性。力学测试结果显示，nHA/PEEK-AgNPs多孔支架的最大压缩强度为(47.4±3.9) MPa，明显高于PEEK组的(36.3±7.3) MPa。同时，最大弹性模量与PEEK组无明显差异，表明复合材料的力学强度与PEEK多孔支架相比有所增强。抑菌实验结果显示，对于大肠杆菌和金黄色葡萄球菌具有明显的抑菌性，抑菌率分别达到(89.4±2.4)%和(85.8±4.4)%。细胞增殖检测结果显示，7 d内nHA/PEEK-AgNPs组在各个时间点的细胞增殖情况均明显优于PEEK组(P<0.05)。此外，nHA/PEEK-AgNPs具有较好细胞相容性和成骨活性。RT-PCR结果显示，14 d内，和PEEK相比，nHA/PEEK-AgNPs组细胞的Runx2基因表达水...     

丝素改性聚乳酸-羟基乙酸共聚物多孔微球作为牙龈间充质干细胞递送载体的研究

利用复乳-溶剂挥发法合成适合细胞三维培养的聚乳酸-羟基乙酸共聚物(PLGA)多孔微球, 并对其表面进行丝素改性, 利用扫描电子显微镜、 能谱、 红外光谱和X射线衍射等对改性前后PLGA多孔微球的理化特性进行表征. 原代培养人牙龈间充质干细胞并进行成骨(茜素红染色)成脂(油红O染色)分化鉴定. 通过负压混悬法将牙龈干细胞负载于丝素改性的PLGA多孔微球上进行5-乙炔基-2'-脱氧尿嘧啶核苷(EdU)细胞增殖及成骨分化研究. 结果表明, 原代培养的牙龈干细胞具有多向分化潜能, 负载在丝素改性的PLGA多孔微球上的细胞有利于细胞增殖. 丝素改性的PLGA多孔微球是良好的细胞递送载体, 为进一步修复牙槽骨缺损提供了科学依据.     

介孔硅酸镁改性硫酸钙骨水泥的降解及成骨性

将介孔硅酸镁(m-MS)掺杂到硫酸钙(CS)中,制备了一种新型复合骨水泥(m-MSC)。结果显示:掺入m-MS,延长了m-MSC的固化时间;提高了其降解速率;掺入m-MS可中和CS降解产生的酸性物质,缓解p H值下降。体外细胞实验显示:m-MSC能促进MC3T3-E1细胞增殖和分化;动物体内植入实验显示:m-MSC的成骨量和Ⅰ型胶原阳性表达率都显著高于CS。     

聚酯多孔支架降解液对骨髓基质干细胞活力和成骨分化的影响

通过室温模压/粒子浸出方法制备得到聚乙交酯丙交酯(PLGA)多孔支架,每个质量50 mg、孔径200～300μm、孔隙率略大于90%的PLGA85/15多孔支架在10 mL磷酸盐缓冲液(PBS)中37℃体外降解24周.降解液每周换一次,不同时间点的降解液被收集、并加入骨髓基质干细胞(MSC)的培养液或者成骨诱导液中,利用胞外乳酸脱氢酶含量检测、细胞死活染色、四唑盐检测、碱性磷酸酶染色和定量检测的方法考察降解液对MSC的活力和成骨分化能力的影响.实验结果表明,PLGA多孔支架材料在PBS中逐渐降解,其质量、尺寸、孔径、孔与孔的连通性、分子量有不同程度的降低;其降解液在本研究的实验条件下未发现对MSC有明显的细胞毒性,对MSC的活力、增殖以及成骨分化均无显著的负面影响.     

介孔硅酸镁改性硫酸钙骨水泥的降解及成骨性

将介孔硅酸镁(m-MS)掺杂到硫酸钙(CS)中,制备了一种新型复合骨水泥(m-MSC)。结果显示:掺入m-MS,延长了m-MSC的固化时间;提高了其降解速率;掺入m-MS可中和CS降解产生的酸性物质,缓解pH值下降。体外细胞实验显示:m-MSC能促进MC3T3-E1细胞增殖和分化;动物体内植入实验显示:m-MSC的成骨量和Ⅰ型胶原阳性表达率都显著高于CS。     

可降解聚乙交酯-丙交酯缓释微球用于甲状旁腺相关肽的持续释放

采用水包油包水(W1/O/W2)复乳溶剂挥发法制备了包载甲状旁腺激素相关肽(PTHrP)的聚乙交酯-丙交酯(PLGA)微球,通过核磁,红外,GPC,扫描电子显微镜等观察PLGA载药微球的结构,表明载药微球具有良好的球形结构,其平均粒径约为8μm.而体外模拟释放表明,此PLGA载药微球能实现PTHrP1-34长达25天的持续释放.并通过MTT法、碱性磷酸酶活性测定等检测负载PTHrP1-34的PLGA微球缓释系统对小鼠成骨细胞MC3T3-E1增殖及分化的影响,结果表明PTHrP1-34浓度为1×10-9mol/L时对MC3T3-E1增殖促进效应最大,且随着药物作用时间的延长,缓释系统促进细胞增殖、分化的作用越明显.     

低热-高压法制备PLGA多孔支架及其体外降解研究

采用低热-高压法制备了聚(dl-丙交酯／乙交酯)75／25(PLGA75／25)组织工程多孔支架。该方法避免了使用有机溶剂，支架的孔隙率在90％以上，孔径大小分布均匀。多孔支架经过酒精处理后，支架表面产生许多微小的凹陷；用藻酸钙改性处理后，支架形态保持良好。两种处理都使支架的压缩强度有所增大，亲水性增强。虽然孔隙率高的支架降解速率稍慢，但其体外降解规律基本一致：特性粘数争力学强度衰减快，而质量损失较慢，降解6周后，支架的质量损失仅为3％左右；体外降解3周后，支架的形态保持良好，可望在细胞移植争组织修复的早期发挥支撑作用。     

Preparation,Characterization, and In Vitro Biological Evaluation of PLGA/Nano-Fluorohydroxyapatite (FHA) Microsphere-Sintered Scaffolds for Biomedical Applications

In this research, the novel three-dimensional (3D) porous scaffolds made of poly(lactic-co-glycolic acid) (PLGA)/nano-fluorohydroxyapatite (FHA) composite microspheres was prepared and characterize for potential bone repair applications. We employed a microsphere sintering method to produce 3D PLGA/nano-FHA scaffolds composite microspheres. The mechanical properties, pore size, and porosity of the composite scaffolds were controlled by varying parameters, such as sintering temperature, sintering time, and PLGA/nano-FHA ratio. The experimental results showed that the PLGA/nano-FHA (4:1) scaffold sintered at 90 °C for 2 h demonstrated the highest mechanical properties and an appropriate pore structure for bone tissue engineering applications. Furthermore, MTT assay and alkaline phosphatase activity (ALP activity) results ascertained that a general trend of increasing in cell viability was seen for PLGA/nano-FHA (4:1) scaffold sintered at 90 °C for 2 h by time with compared to control group. Eventually, obtained experimental results demonstrated PLGA/nano-FHA microsphere-sintered scaffold deserve attention utilizing for bone tissue engineering.     

Oxygen Plasma Technology-Assisted Preparation of Three-Dimensional Reduced Graphene Oxide/Polypyrrole/Strontium Composite Scaffold for Repair of Bone Defects Caused by Osteoporosis

Repairs of bone defects caused by osteoporosis have always relied on bone tissue engineering. However, the preparation of composite tissue engineering scaffolds with a three-dimensional (3D) macroporous structure poses huge challenges in achieving osteoconduction and osteoinduction for repairing bone defects caused by osteoporosis. In the current study, a three-dimensional macroporous (150–300 μm) reduced graphene oxide/polypyrrole composite scaffold modified by strontium (Sr) (3D rGO/PPY/Sr) was successfully prepared using the oxygen plasma technology-assisted method, which is simple, safe, and inexpensive. The findings of the MTT assay and AO/EB fluorescence double staining showed that 3D rGO/PPY/Sr has a good biocompatibility and effectively promoted MC3T3-E1 cell proliferation. Furthermore, the ALP assay and alizarin red staining showed that 3D rGO/PPY/Sr increased the expression levels of ALP activity and the formation of calcified nodules. The desirable biocompatibility, osteoconduction, and osteoinduction abilities, assure that the 3D macroporous rGO/PPY/Sr composite scaffold offers promising potential for use in the repair of bone defects caused by osteoporosis in bone tissue engineering.     

Effect of surface-modified collagen on the adhesion, biocompatibility and differentiation of bone marrow stromal cells in poly(lactide-co-glycolide)/chitosan scaffolds

The material-driven differentiation of bone marrow stromal cells (BMSCs) is a critical issue in regeneration medicine. In this study, we showed the differentiation of BMSCs in 3-D scaffolds consisting of collagen, poly(lactide-co-glycolide) (PLGA) and chitosan. The results revealed that the collagen-grafted PLGA/chitosan scaffolds yielded little cytotoxicity to BMSCs. The scaffold containing type I collagen of 640μg/mL was about 1.2 times the cell adhesion efficiency of the corresponding unmodified scaffold. In addition, the modification of type I collagen with the density of 640μg/mL increased about 1.3 times the cell viability and 1.2 times the biodegradation, respectively. The differentiation of BMSCs in PLGA/chitosan scaffolds produced osteoblasts with mineral deposition on the substrate. Moreover, the surface collagen promoted the formation of mineralized tissue and reduced the amount of phenotypic BMSCs in the constructs. However, the induction with neuron growth factor (NGF) inhibited osteogenesis and guided the differentiation of BMSCs towards neurons in the constructs. Therefore, the combination of collagen-functionalized PLGA/chitosan scaffolds, NGF and BMSCs can be promising in neural tissue engineering.     

Optimization of fibrin gelation for enhanced cell seeding and proliferation in regenerative medicine applications

In order to improve the cell seeding efficiency and cell compatibility inside porous tissue scaffolds, a method of fibrin gel‐mediated cell encapsulation inside the scaffold was optimized. Disc‐type poly(d ,l ‐glycolic‐co‐lactic acid) (PLGA) scaffolds without a dense surface skin layer were fabricated using an established solvent casting and particulate leaching method as a model porous scaffold, which showed high porosity ranging from 90 ± 2% to 96 ± 2%. The thrombin and fibrinogen concentration as precursors of fibrin gel was varied to control the gelation kinetics as measured by rheology analysis, and optimized conditions were developed for a uniform fibrin gel formation with the target cells inside the porous PLGA scaffold. The fibroblast cell seeding accompanied by a uniform fibrin gel formation at an optimized gelation condition inside the PLGA scaffold resulted in an increase in cell seeding efficiency, a better cell proliferation, and an increase in final cell density inside the scaffold. Scanning electron microscopy images revealed that cells were better spread and grown by fibrin gel encapsulation inside scaffold compared with the case of bare PLGA scaffold. Copyright © 2016 John Wiley & Sons, Ltd.     

Morphological,mechanical, and in vitro cytocompatibility analysis of poly(vinyl alcohol)–silica glass hybrid scaffolds reinforced with cellulose nanocrystals

Cellulose nanocrystal-reinforced poly(vinyl alcohol)/silica glass hybrid scaffolds were fabricated using the freeze-drying method. In this study, we develop molecular-level-based hybrid scaffolds with possible bioactivity behavior by adding silica sol–gel. The results showed a highly porous structure and a significant improvement in mechanical performance (stiffness) of hybrid scaffolds with an increased content of cellulose nanocrystals followed by the addition of silica-based bioactive glass. In vitro cell study with MC3T3-E1 cells on hybrid scaffolds for 1 and 3 days revealed good cell adhesion and growth. Thus, the obtained hybrid scaffold may be a competitive candidate for bone tissue engineering applications.     

A porous hydrogel scaffold mimicking the extracellular matrix with swim bladder derived collagen for renal tissue regeneration

As a worldwide public health issue, chronic kidney disease still lacks of effective therapeutic approaches due to the challenges in conventional organ transplantation and dialysis. Renal tissue engineering offers an advantageous therapeutic or regenerative option over typical donor organ. However, despite the great progress of decellularized extracellular matrix based scaffold for the renal regeneration, several safety concerns and complex composition still remain to be addressed. Herein, the extracellular matrix-mimicking hydrogel scaffolds were developed through covalent and physical cross-linking between swim bladder-derived natural collagen (COL) and anti-fibrosis chondroitin sulfate (CS) derivatives. The biomimetic hydrogels showed proper mechanical property, excellent thermal stability and high biocompatibility both in vitro and in vivo, by altering the mass ratio of COL and CS. When implanted in partially nephrectomized rat model, the 1COL/2CS scaffold enable it recruit more native kidney cells, reduce the tubular damage, and even induce the regeneration of renal tubular-like tissue and restore renal metabolic function more effectively comparing with the pure 2COL and 2CS scaffold. These results suggest that the biomimetic scaffold is a promising functional platform for treating renal diseases.