Evaluation of the Behaviour of Wrinkles Fibroblasts and Normal Aged Fibroblasts in the Presence of Poly-L-Lactic Acid

Background: Wrinkles are characterized by changes in the organization and structure of the dermis. Human wrinkle fibroblasts (WF) have a different functional behaviour in comparison with normal-aged fibroblasts (NF). Decreases in migration capacities and collagen I synthesis are observed. Mitochondrial function is impaired with an increase in lactate production during aging. Sculptra? (poly-L-lactic acid: PLLA), a biodegradable synthetic polymer, is used for subcutaneous volume restoration. Thus we decided to investigate different fibroblast functions when placed in contact with PLLA. Objectives: The potential of PLLA to compensate for the reduction of metabolic activity, to restore the migration capacity of WF and to inhibit the lactate production, was investigated and compared to NF. Methods: Two different skin samples were used from each of the three women’s facelift (one inside a face wrinkle and one from normal aged skin). Collagen I, lactate productions and proliferation capacities were investigated on monolayer cultures. Migration properties were evaluated using three-dimensional collagen lattices. Results: PLLA increased collagen I synthesis, restored migration capacities and tended to decrease lactate production in WF, whereas PPLA stimulated proliferation in NF and tended to improve the migration of NF. Conclusion: These results suggested that PLLA from Sculptra? acted as a stimulus for collagen production in WF and that it is suitable for correcting skin depressions, such as wrinkles.

The Effect of Annealing Treatments on Spherulitic Morphology and Physical Ageing on Glass Transition of Poly Lactic Acid (PLLA)

Spherulitic morphology of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The morphology of spherulite of pure poly lactic acid (PLLA) PLLA have investigated after thermal annealing. The effect of both annealing temperature and crystallization temperature on the formation of cracks was described by polarized optical microscope (POM). Non banded spherulite (fibrils) with cracks was detected in PLLA film after annealing at 160°C (180 min.) and isothermal crystallization temperatures at 140°C and 150°C. With increasing temperature after annealing treatment the size of spherulite is increased and more cracks are formed. The maximum growth rate of spherulites was found at 130°C. The physical ageing was carried out by annealing the PLLA sample at room temperature for several annealing time (ta) from 0 h to 720 h. The enthalpy relaxation has been studied by differential scanning calorimetry (DSC) through analysis of the endothermic peak of glass transition temperature, which increased and shifted towards higher temperature as the annealing time increased.

Adipose-derived mesenchymal stem cell-incorporated PLLA porous microspheres for cartilage regeneration

Background:In facial plastic surgery,patients with nasal deformity are often treated by rib cartilage transplantation.In recent years,cartilage tissue engineering has developed as an alternative to complex surgery for patients with minor nasal defects via injection of nasal filler material.In this study,we prepared an injectable nasal filler material containing poly-L-l actic acid(PLLA)porous microspheres(PMs),hyaluronic acid(HA)and adipose-derived mesenchymal stem cells(ADMSCs).Methods:We seeded ADMSCs into as-prepared PLLA PMs using our newly invented centrifugation perfusion technique.Then,HA was mixed with ADMSC-i ncorporated PLLA PMs to form a hydrophilic and injectable cell delivery system(ADMSCincorporated PMH).Results:We evaluated the biocompatibility of PMH in vitro and in vivo.PMH has good injectability and provides a favorable environment for the proliferation and chondrogenic differentiation of ADMSCs.In vivo experiments,we observed that PMH has good biocompatibility and cartilage regeneration ability.Conclusion:In this study,a injectable cell delivery system was successfully constructed.We believe that PMH has potential application in cartilage tissue engineering,especially in nasal cartilage regeneration.

PLLA／CPC复合支架增强结构设计及制备

为制备用于负重部位骨缺损修复的人工植入体,提出了一种复合增强结构人工骨设计及制备方案,该方案 采用聚左旋乳酸支架(PLLA)为增强结构,以自凝固磷酸钙骨水泥(CPC)为复合填充材料,制备了复合增强结构人 工骨。研究了PLLA的棒材力学性能、支架设计和制作及其不同增强结构形式对人工骨力学性能的影响。力学试 验结果表明,所制作的人工骨有效提高了承载能力,并且该复合结构能有效弥补金属骨无法降解的缺陷。

成骨诱导的大鼠骨髓间充质干细胞与不同比例的β-TCP/PLLA支架材料复合的研究

种子细胞、支架材料及二者的相互作用是骨组织工程需要解决的三大问题。骨髓间充质干细胞(Mesenchym al stem cells,MSCs)是一种很有潜力的种子细胞,但挑选什么样的MSCs作为种子细胞目前研究尚少;而材料方面,研制力学性能和生物相容性均好的可降解多孔支架材料一直是研究者努力的方向。为了挑选处于最佳时期的种子细胞以及最适比例的β- TCP/PL L A多孔支架材料,我们观察并检测了大鼠MSCs(r MSCs)成骨诱导后不同时期细胞的形态及功能,发现r MSCs成骨诱导后10 d左右开始进入增殖期,14 d左右进入基质合成期,2 0 d左右进入矿化结节期(但三者不是截然分开的) ,从而根据实验目的挑选出能作为骨组织工程用的最佳细胞。将该时期的种子细胞与不同比例的β- TCP/PL L A多孔支架材料复合后,通过荧光显微镜、扫描电镜以及MTT等方法初步比较了不同比例的材料对细胞生长状况的影响,结果显示不同比例的材料均具有一定的生物相容性,细胞生长良好。但以β- TCP/PL L A=2∶1的材料最好,对细胞的生长影响最小。

RGD功能化HA/PLLA多孔复合材料的制备和表征

通过碳二亚胺法将精氨酸-甘氨酸-天冬氨酸(RGD)接枝到羟基磷灰石(HA)颗粒表面,增强HA颗粒识别细胞的功能,然后将其均匀地分布于左旋聚乳酸(PLLA)中制备多孔复合材料,分别用XPS和SEM等对HA颗粒和多孔复合材料进行了表征。结果表明:RGD成功地接枝到了HA颗粒表面,多孔复合材料中RGD功能化的HA颗粒是纳米尺寸的,且分布均匀;RGD功能化HA/PLLA多孔复合材料的细胞粘附率从普通HA/PLLA多孔复合材料的37.21%提高到了69.11%。

高分子量立构复合结晶的三枝化PPO-PDLA-PLLA嵌段共聚物

以三枝化低不饱和度聚环氧丙烷(PPO)引发D-丙交酯(D-LA)逐步开环聚合,合成了三枝化聚环氧丙烷-聚右旋乳酸(PPO-PDLA)共聚物.用辛酸亚锡Sn(Oct)2与PPO-PDLA端羟基反应进行Sn(Oct)封端,制备了三枝化PPO-PDLA-Sn(Oct)预聚物.再于130℃下,以其作为大分子引发剂与L-丙交酯(L-LA)开环聚合,合成了分子量>105的三枝化PPO-PDLA-PLLA嵌段共聚物.活性端基的引入,降低了聚合反应温度,从而降低了聚合中的酯交换或热降解反应发生的概率.实现了高分子量PPO-PDLA-PLLA嵌段共聚物的合成.结构测试结果表明,合成的嵌段共聚物具有分子结构易控及立构规整度高等特点.在结晶-熔融-再结晶重复热处理下,三枝化PPO-PDLA-PLLA嵌段共聚物仅发生立构复合聚乳酸结晶,且结晶能力稳定.

新型聚乳酸/β-磷酸三钙(PLLA/β-TCP)多孔支架材料的性能研究

选择含有70%β-磷酸三钙加入聚乳酸中,致孔剂含量为70%(质量分数),制作成孔径为200～400μm的复合多孔支架材料,将其压成直径为5 mm、高为5 mm的圆柱体形状。将大鼠的骨髓间充质干细胞(BMSCs,Bone Mesenchymal Stem Cells)经过体外分离培养、传代诱导后,与多孔聚乳酸/β-磷酸三钙支架材料在培养板内共同培养1、3、5、7、10、14 d。采用扫描电镜观察、MTT法及ALP检测试剂盒等方法检测BMSCs在材料表面的粘附、增殖和分化能力。检测结果显示:BMSCs能在该支架材料表面早期粘附和增殖,在体外共同培养时BMSCs大量增殖后维持其碱性磷酸酶活性。此种方法制造的多孔聚乳酸/β-磷酸三钙复合支架材料有望成为组织工程骨支架材料。

In Vitro Characterizations of PLLA/β-TCP Porous Matrix Materials and RMSC-PLLA-β-TCP Composite Scaffolds

To develop a novel degradable poly (L-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) bioactive materials for bone tissueengineering, β-TCP powder was produced by a new wet process. Porous scaffolds were prepared by three steps, i.e. solventcasting, compression molding and leaching stage. Factors influencing the compressive strength and the degradation behaviorof the porous scaffold, e.g. weight fraction of pore forming agent-sodium chloride (NaCl), weight ratio of PLLA: β-TCP,the particle size of β-TCP and the porosity, were discussed in details. Rat marrow stromal cells (RMSC) were incorporatedinto the composite by tissue engineering approach. Biological and osteogenesis potential of the composite scaffold weredetermined with MTT assay, alkaline phosphatase (ALP) activity and bone osteocalcin (OCN) content evaluation. Resultsshow that PLLA/β-TCP bioactive porous scaffold has good mechanical and pore structure with adjustable compressive strengthneeded for surgery. RMSCs seeding on porous PLLA/β-TCP composite behaves good seeding efficacy, biocompatibility andosteoinductive potential. Osteoprogenitor cells could well penetrate into the material matrix and begin cell proliferation andosteogenic differentiation. Osseous matrix could be formed on the surface of the composite after culturing in vitro. It isexpected that the PLLA/β-TCP porous composites are promising scaffolds for bone tissue engineering in prosthesis surgery.

3D打印PLCL/PLLA复合材料支架的体外降解性能研究

目的探讨左旋聚乳酸(PLLA)与聚-L-丙交酯-己内酯(PLCL)的复合对PLCL的三维(3D)打印性能及其打印支架降解性能的影响。方法采用共混手段制备了系列不同比例的PLCL(100%、90%、80%、70%、60%、50%)为基质相、PLLA(10%、20%、30%、40%、50%、100%)为分散相的复合材料;利用熔融沉积成型(FDM)3D打印技术,制备不同比例、不同填充率(40%、50%、60%、70%)的PLCL/PLLA无边框3D多孔支架;通过支架宏/微观结构的观察及其体外加速降解实验,考察复合材料3D打印性能及其支架的降解性能。结果在研究条件下,复合材料均可打印成孔隙贯通的多孔支架,复合材料的孔径随填充率的增加而缩小,由40%时733μm缩小为70%时200μm。相对于单纯PLCL,复合PLLA更有利于支架结构成型。降解实验显示:PLCL支架降解较快,70%填充率打印支架60 d时降解达到88.58%,而PLLA的加入可以减慢支架降解速率;降解过程中,所有支架都较好地保持了原有结构的完整性,无明显断裂或崩解,但PLCL支架整体结构缩小、孔径增大明显,而复合PLLA明显改善了支架缩小和孔径增大的现象;微观形貌变化显示,PLCL支架表面在降解过程中出现了大量微孔结构,而PLCL/PLLA复合材料支架表面出现了微孔结构和微裂缝结构。结论复合PLLA不仅改善了PLCL的3D打印性能,而且也改变了复合材料支架的降解性能;通过改变PLCL和PLLA的比例及3D打印填充率,可以调控支架的孔径、孔隙率及降解速率,为多种组织、器官的工程化构建提供可选择的支架材料。

The Assembly of C60 in Semicrystalline PLLA Matrix

It has increasingly become a research focus to build higher structure composed of C60. However, there has been very few reports on the influence of polymer addition on the self-assembling behavior of fullerene in organic solvents. In this research, big needle-like C60 assemblings have been obtained in the form of PLLA/C60 composites. The largest C60 needles can be observed by naked eyes. The amount of C60 in the composite influences the length of C60 needles to some extent. DSC results indicate C60 accelerates the crystallization and lift the relative crystallinity of PLLA matrix. the results also imply the addition of semicrystalline PLLA influence the assembling behavior of C60. i.e., the crystallization of PLLA accelerated by C60 also act a driving force for the enriching and the linear assembling of C60 in PLLA matrix via Van der Waals force.

COMPUTATION OF FLEXURAL PROPERTIES OF HA/PLLA COMPOSITE USING A CELL MODEL APPROACH

A three-dimensional finite element analysis was conducted to evaluate the feasibility of predicting the flexural properties of hydroxyapatite-reinforced poly-L-lactide acid （HA/PLLA） biocomposite using three different schemes. The scheme 1, originated from a beam analysis, was used to determine the flexural modulus analytically while the scheme 2 and 3 were designed to have different loading and boundary conditions using a finite element cell modeling approach. An empirical approach using Chow＇s formula and experimental data were used for comparison with the predicted results. In order to reduce the computational time and save the storage space involved in determining the effect of varying particle volume fractions on the flexural properties of HA/PLLA, a superelement technique was applied. The results using the scheme 3 and the Chow＇s formula were found to be in reasonable agreement with experimental results over the range of particle volume fraction. In addition to the Chow＇s formula, local stress distribution and the failure processes in HA/PLLA were simulated using the finite element technique.

苎麻纤维PLLA-PEG复合材料制备工艺的优化

以PLLA、PEG的熔融共聚体为基体,以麻纤维为增强体.通过正交实验优化工艺参数,模压成型得到苎麻纤维PLLA-PEG复合材料板.分析复合材料的拉伸、弯曲性能及红外光谱、断面形貌.结果表明,当PLLA与PEG质量比为9∶1,共聚温度为120℃,TDI用量为1∶12(与PLLA的质量比),共聚时间为14h时,得到的复合材料板性能最优.其拉伸强度为11.1MPa,弯曲强度为68.48MPa.

红外成像研究PLLA/N-CQDs复合薄膜的结晶性能

将水热法制得的氮掺杂碳量子点(N-CQDs)加入聚乳酸(PLLA)基质中,以溶剂浇铸法制备了PLLA/N-CQDs复合薄膜,并通过红外成像分析了N-CQDs的加入对PLLA结晶性能的影响。结果显示,加入N-CQDs可以显著提高PLLA的结晶性能。

PLLA/TCP复合骨组织载体框架的低温挤出成形

为制备骨组织工程的细胞与因子的三维载体框架,提出了聚左旋乳酸/磷酸三钙(PLLA/TCP)复合材料快速成形的低温挤出成形工艺,研究了此工艺制备骨组织载体框架的设备与工艺过程。分析了制备的载体框架的孔隙结构、孔隙率、力学性能,并通过犬桡骨20mm节段性缺损的修复实验分析了制备的载体框架的生物相容性、体内降解性能和骨传导性能。制备的载体框架具有良好的综合性能,可以作为骨组织再生修复的载体框架。

THE SYNTHESIS AND CHARACTERIZATION OFPOLY-L-LACTIDE USED FOR THE INTERNALFIXATION OF BONE FRACTURE

A high Mw of PLLA was synthesized, it intended to be used in the manufacture ofbioabsorbable screw applied in bone fracture internal fixation. The optical reactionconditions have been discussed.

Interaction of Human Fibroblasts with Electrospun Composites Gelatin/PLLA,Chitosan/PLLA and PLLA Fibrous Scaffolds

Highly porous ultrafine electrospun scaffolds,gelatin/poly(L-lactic acid)(PLLA) and chitosan/PLLA were prepared by blending gelatin and PLLA,chitosan and PLLA respectively.The biocompatibilities of these scaffolds were assessed by attachment,proliferation and viability of cells on them.The results indicated that over 30%WI-38 cells could attach to the gelatin/PLLA and chitosan/PLLA scaffolds at 2 h after seeding,while the attachment of the cells was only 15%on PLLA scaffolds.Both gelatin/PLLA and chitosan/PLLA scaffolds also exhibited a very good ability for proliferation of WI-38 cells.Cell growth on the gelatin/PLLA and chitosan /PLLA scaffolds showed dramatic improvement,indicating a much better biocompatibility in the blends contributed by gelatin and chitosan.3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) assay also demonstrated gelatin/PLLA showed better ability to enhance the growth and functions of the cells.These assays suggest that the electrospun gelatin/PLLA and chitosan/PLLA scaffolds are promising biomaterials with great biocompatibility for the development of skin tissue engineering.

拉伸对聚左旋乳酸结晶的影响

采用红外光谱、差示扫描量热分析及X射线衍射等方法研究了在不同温度下拉伸对聚左旋乳酸(PLLA)结晶行为的影响.结果表明,在合适的温度条件下,拉伸能迅速提高PLLA的结晶速度和结晶度.对经过拉伸预处理但未结晶的PLLA样品进行等温及非等温结晶的研究发现,经过拉伸预处理的PLLA样品的结晶速率和结晶度都得到提高,表明预拉伸会影响PLLA在后续过程中的结晶行为.

基于不同溶液体系载药纳米纤维膜的制备

以不同配比的丙酮与二氯甲烷为溶剂体系,选用不同黏均分子质量的左旋聚乳酸,通过改变药物的添加比例来调节纺丝溶液的性能,并运用扫描电镜分析静电纺纳米纤维膜的形貌,探求其与溶液性能之间的关系。结果表明:仅以丙酮为溶剂,因溶液体系黏度低而表面张力大,收集到的只是大量的珠子;以m(丙酮)∶m(二氯甲烷)=1∶2为溶剂,聚乳酸的分子质量为1×105,质量分数为10%时,制备的纤维无串珠且分布较好;向溶液中加入碱性药物克拉霉素时,成纤的聚乳酸质量分数相应减小,溶液的导电性能增加,收集到的纤维直径变细,分布变得混乱。