马来酸酐改性聚乳酸对成骨细胞黏附、增殖和分化的研究

通过研究马来酸酐改性聚乳酸(MPLA)和聚乳酸(PDLLA)材料表面对MC3T3-E1成骨细胞形态、黏附、增殖、细胞总蛋白含量、碱性磷酸酶活性及细胞分泌无机钙含量的影响,评价MPLA和PDLLA材料的细胞相容性。结果显示:与PDLLA相比,MPLA材料上的成骨细胞完全黏附和充分铺展;MPLA材料上细胞的增殖速率、细胞总蛋白含量、细胞碱性磷酸酶活性及细胞分泌的无机钙含量都显著高于PDLLA(P<0.01)。这些结果说明,MPLA材料能促进MC3T3-E1成骨细胞的黏附、铺展、增殖及蛋白质的合成,并能促进成骨细胞的分化和矿化,与PDLLA材料相比具有更好的细胞相容性。     

壳聚糖改性聚醚醚酮表征及对MC3T3-E1细胞黏附、增殖的影响

背景：聚醚醚酮的生物惰性表面限制了其医学应用,如何提高聚醚醚酮的生物活性亟待解决。目的：分析壳聚糖生物活性涂层改性聚醚醚酮的表面特征及其对MC3T3-E1细胞增殖、黏附的影响。方法：取圆片状聚醚醚酮材料,依次进行NaBH4、3-氨丙基三乙氧基硅烷、戊二醛水溶液及壳聚糖溶液处理,获得壳聚糖生物活性涂层改性的聚醚醚酮材料。使用X射线光电子能谱、扫描电镜、原子力显微镜与全自动接触角测量仪观察化学处理前后聚醚醚酮材料的表面特征。将MC3T3-E1细胞分别接种于聚醚醚酮与壳聚糖改性聚醚醚酮材料表面,观察细胞的增殖与黏附情况。结果与结论：(1)X射线光电子能谱检测显示,聚醚醚酮材料仅含有C、O元素,壳聚糖改性聚醚醚酮材料含有C、O、N、Si元素;壳聚糖改性聚醚醚酮材料表面的接触角小于聚醚醚酮材料(P <0.05);(2)扫描电镜下可见,聚醚醚酮材料表面有明显的凹槽状起伏,壳聚糖改性聚醚醚酮材料表面存在壳聚糖分子,大小为1.0-2.0μm;原子力显微镜下可见,聚醚醚酮材料表面有较多的微小凹坑,大小约为0.1μm,壳聚糖改性聚醚醚酮材料表面的凹坑增大,大小为0.2-0.5μm,表面粗糙度大于聚醚...     

MC3T3-E1细胞与多组分纳米羟基磷灰石基三维复合支架材料的相容性

目的 观察MC3T3-E1细胞在复合支架材料上的黏附、增殖及形态,评价多组分纳米羟基磷灰石基三维复合支架材料的生物相容性.方法 采用仿生学方法,将壳聚糖、羟基磷灰石、明胶、果胶按照一定比例制作成多组分纳米羟基磷灰石基三维复合支架材料.在复合支架材料上接种MC3T3-E1细胞,通过倒置相差显微镜、HE染色、扫描电镜、四甲...     

表面矿化修饰煅烧骨/P24活性多肽仿生骨材料对MC3T3-E1细胞黏附、增殖和向成骨方向分化的影响

本研究目的是评价表面矿化修饰煅烧骨/P24活性多肽复合仿生骨材料对小鼠MC3T3-E1细胞黏附、增殖和诱导成骨分化的影响。实验分三组:A组为表面矿化修饰煅烧骨加骨形态发生蛋白-2(BMP-2)活性多肽P24修饰的复合仿生骨材料,B组为表面矿化修饰煅烧骨材料,C组为单纯的煅烧骨材料。三组材料在细胞实验前行电镜扫描观察。然后将小鼠MC3T3-E1细胞分别种植在三种材料表面,测定细胞的黏附率,MTT法检测细胞体外增殖活性,同时通过碱性磷酸酶(ALP)染色和ALP活性检测,了解小鼠MC3T3-E1细胞成骨分化情况。电镜观察显示三组材料均保留了天然的孔隙结构,孔径为200~850μm。细胞黏附率和MTT实验显示,A组MC3T3-E1细胞在材料表面的黏附性能和增殖能力明显高于B组和C组,B组则高于C组,组间差异均有统计学意义(P0.05)。ALP染色和ALP活性检测显示:A组细胞ALP活性明显高于B组和C组,B组则高于C组,组间差异均有统计学意义(P0.05)。研究表明表面矿化修饰煅烧骨/P24活性多肽仿生骨材料能促进小鼠MC3T3-E1细胞在骨基质材料表面的黏附、增殖与分化,并能较好地保持细胞的形态。     

3D打印高密度聚乙烯支架表面涂层的性能

背景：高密度聚乙烯常用作颅颌面骨缺损的修复材料,然其制备方式及表面活性仍需进一步改进。目的：优化高密度聚乙烯制备方法,改善高密度聚乙烯表面活性。方法：基于挤出式3D打印技术制备高密度聚乙烯支架,将支架依次浸入多巴胺溶液、模拟体液中进行聚多巴胺、羟基磷灰石涂层。表征涂层前后支架的微观形貌、亲水性和压缩模量。在支架表面分别接种小鼠胚胎成骨前体细胞MC3T3-E1和人脐静脉内皮细胞,评估涂层前后支架的细胞相容性、早期成骨活性和促血管活性。结果与结论：(1)3D打印的高密度聚乙烯支架纤维排列规则,孔隙均匀;表征结果显示,支架表面聚多巴胺、羟基磷灰石改性成功;与未改性支架相比,聚多巴胺涂层与聚多巴胺+羟基磷灰石涂层改性后的支架表面水接触角明显减小(P <0.05),压缩模量未发生明显变化;(2)与未改性支架相比,聚多巴胺涂层与聚多巴胺+羟基磷灰石涂层改性后的支架可促进MC3T3-E1细胞、人脐静脉内皮细胞的黏附(P <0.05),且双涂层改性组促细胞黏附优于单涂层改性组(P <0.05);与未改性支架相比,聚多巴胺涂层与聚多巴胺+羟基磷灰石涂层改性后的支架可促进MC3T3-E1...     

钛表面微弧氧化涂层的细胞生物活性

背景：微弧氧化技术可改善钛或钛合金的表面特征。 目的：研究纯钛表面微弧氧化涂层的表面性能及其对MC3T3-E1细胞早期黏附、增殖及成骨能力的影响。 方法：将46个直径10 mm、厚度2 mm圆盘状纯钛试件分为实验组和对照组。实验组置于含0.02 mol/Lβ-甘油磷酸二钠盐及0.2 mol/L乙酸钙的电解液中进行微弧氧化处理,对照组对试件进行机械抛光。扫描电子显微镜观察试件表面形貌,X射线能谱分析检测涂层表面钙磷比,X射线衍射分析检测涂层晶相构成。将MC3T3-E1细胞接种在两组试件表面,1,2,4 h电镜下观察细胞形态,在2,4,7 d通过CCK-8方法检测细胞增殖,并于7,14 d检测碱性磷酸酶活性。 结果与结论：经微弧氧化处理后,钛表面形成粗糙多孔的钙磷涂层,微弧氧化涂层主要元素为Ca、P、O及Ti,微弧氧化膜层主要由氧化钛、钛酸钙、磷酸钙及偏磷酸钙构成。电镜观察显示1 h 微弧氧化涂层表面细胞已伸出伪足,4 h呈现较典型的细胞形态。细胞在微弧氧化处理钛表面4,7 d的细胞增殖和7,14 d的碱性磷酸酶活性高于对照组。表明微弧氧化技术生成的粗糙多孔钙磷涂层能显著促进MC3T3-E1细胞的早期黏附、增殖及成骨活性。     

不同孔径梯度纳米羟基磷灰石三维支架制备及对MC3T3-E1生物学性能的影响

背景：骨组织工程支架孔径是评估其物理性能的重要因素,寻求孔径及力学性能二者的最佳结合点一直是骨组织工程亟待解决的问题。目的：制备不同孔径梯度的三维支架,并研究其对MC3T3-E1细胞生物学行为的影响。方法：将直径300,500,800μm的蜡球造孔剂分别与羟基磷灰石混合,采用改良型粒子浸出法制备孔径均一的纳米羟基磷灰石三维支架,分别记为D300、D500、D800组支架;将3种直径的蜡球从小到大依次堆积,采用改良型粒子浸出法制备孔径梯度纳米羟基磷灰石三维支架,记为D-Gradient组支架,检测4组支架的孔隙率。将MC3T3-E1细胞分别接种于4组支架上,以细胞单独培养的为空白对照组,检测细胞增殖活性、碱性磷酸酶活性、细胞黏附及细胞骨架重排与成骨分化标志性因子转录水平。结果与结论：(1)4组支架的孔隙率为60%-80%;(2)接种24 h后,各组支架均可促进MC3T3-E1细胞的增殖,增殖指数大小为：D-Gradient组>D500组>D800组>D300组>空白对照组;D300组、D500组、D-Gradient组支架均可促进MC3T3-E1细胞碱性磷酸酶的分...     

聚甲基丙烯酸甲酯/矿化胶原/Mg-Ca合金复合材料与小鼠前成骨细胞的成骨分化

背景:课题组前期通过冷冻干燥方法制备的矿化胶原/Mg-Ca合金复合体结构松散,使用聚甲基丙烯酸甲酯骨水泥作为外层加强层对其进行改良可增强复合材料的结构稳定性。目的:探讨聚甲基丙烯酸甲酯/矿化胶原/Mg-Ca合金复合材料对MC3T3-E1细胞成骨分化的影响。方法:分别制备聚甲基丙烯酸甲酯/矿化胶原/Mg-Ca合金、聚甲基丙烯酸甲酯/矿化胶原复合材料。将MC3T3-E1细胞分别接种于聚甲基丙烯酸甲酯/矿化胶原/Mg-Ca合金(A组)、聚甲基丙烯酸甲酯/矿化胶原复合材料(B组)及Mg-Ca合金材料(C组)上,以单独培养的细胞为空白对照(D组),扫描电镜下观察材料表面的细胞黏附形态,通过CCK-8、碱性磷酸酶活性、酶联免疫吸附实验、RT-PCR与Western blot检测分析3种材料对MC3T3-E1细胞增殖及成骨分化的影响。结果与结论:(1)扫描电镜下可见,MC3T3-E1细胞在A组复合材料表面黏附数量最多,生长状态良好,细胞拉伸明显,伪足伸出较多,细胞相互连接成网状结构;(2)CCK-8实验显示,与D组相比,3种材料均可促进MC3T3-E1细胞的增殖(P <0.05),其中以A组复...     

壳聚糖-脱细胞真皮三维材料作为骨组织工程支架材料的研究

目的观察MC3T3-El成骨前体细胞在壳聚糖-脱细胞真皮三维支架材料上的黏附情况,并评价其细胞相容性。方法通过冷冻干燥制备壳聚糖-脱细胞真皮三维支架材料,并测试其孔隙率、密度和吸水率,通过扫描电镜分析支架的微观形貌。采用体外培养细胞的方法,将MC3T3-E1细胞直接接种到壳聚糖-脱细胞真皮三维支架材料上,培养2,3,4,5h,各时间点各取3个样品,测定细胞在支架上的黏附率,确定最佳的细胞贴壁时间。将细胞接种到支架上,共培养1,3,5,7,9,11,13d,采用MTS方法绘制细胞增殖曲线,组织化学染色观察细胞形态,并利用材料试验机测试不同时间材料细胞复合物的压缩弹性模量。结果壳聚糖-脱细胞真皮材料具有连通的多孔结构,孔隙率为92.8%,密度为97.96g/L,吸水率为(2169±100)%。细胞相容性实验显示,成骨细胞易于在支架材料上黏附、增殖。结论壳聚糖-脱细胞真皮材料具有连通的孔隙,孔径较均匀,MC3T3-El成骨前体细胞易在壳聚糖-脱细胞真皮三维支架材料上黏附、增殖,表明该支架材料具有良好的细胞相容性。     

MC3T3-E1成骨细胞在微格式化表面的黏附

细胞在材料表面的黏附对细胞的增殖和分化志重要作用。格式化表面提供了对细胞在基底的空间分布和黏附进行控制的方法。本文利用微制作利用微制作形成的格式模板，分别以微接触转印法和微流道法形成格式化表面，使MC3T3－E1成骨细胞以一定的格式黏附于表面上，在微接触转印法形成的含二氯二甲基硅烷（DMS）的疏水区域和不含DMS的亲水区域相间隔的表面，细胞优先在亲水区域黏附，在微流道法形成的胶原和白蛋白格式化表面，细胞优先黏附于含胶原区域，结果还表明微格式化表面可以用于研究表面的物理化学性质对细胞的黏附等功能的影响。     

Preparation,mechanical properties and in vitro cytocompatibility of multi-walled carbon nanotubes/poly(etheretherketone) nanocomposites

Desired bone repair material must have excellent biocompatibility and high bioactivity. Moreover, mechanical properties of biomaterial should be equivalent to those of human bones. For developing an alternative biocomposite for load-bearing orthopedic application, combination of bioactive fillers with polymer matrix is a feasible approach. In this study, a series of multi-walled carbon nanotubes (MWCNTs)/poly(etheretherketone) (PEEK) bioactive nanocomposites were prepared by a novel coprecipitation-compounding and injection-molding process. Scanning electron microscope (SEM) images revealed that MWCNTs were adsorbed on the surface of PEEK particles during the coprecipitation-compounding process and dispersed homogeneously in the nanocomposite because the conjugated PEEK polymers stabilized MWCNTs by forming strong π–π stack interactions. The mechanical testing revealed that mechanical performance of PEEK was significantly improved by adding MWCNTs (2–8 wt%) and the experimental values obtained were close to or higher than that of human cortical bone. In addition, incorporation of MWCNTs into PEEK matrix also enhanced the roughness and hydrophilicity of the nanocomposite surface. In vitro cytocompatibility tests demonstrated that the MWCNTs/PEEK nanocomposite was in favor of cell adhesion and proliferation of MC3T3-E1 osteoblast cells, exhibiting excellent cytocompatibility and biocompatibility. Thus, this MWCNTs/PEEK nanocomposite may be used as a promising bone repair material in orthopedic implants application.     

Cytocompatibility,osseointegration, and bioactivity of three-dimensional porous and nanostructured network on polyetheretherketone

Porous biomaterials with the proper three-dimensional (3D) surface network can enhance biological functionalities especially in tissue engineering, but it has been difficult to accomplish this on an important biopolymer, polyetheretherketone (PEEK), due to its inherent chemical inertness. In this study, a 3D porous and nanostructured network with bio-functional groups is produced on PEEK by sulfonation and subsequent water immersion. Two kinds of sulfonation-treated PEEK (SPEEK) samples, SPEEK-W (water immersion and rinsing after sulfonation) and SPEEK-WA (SPEEK-W with further acetone rinsing) are prepared. The surface characteristics, in vitro cellular behavior, in vivo osseointegration, and apatite-forming ability are systematically investigated by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, cell adhesion and cell proliferation assay, real-time RT-PCR analysis, micro-CT evaluation, push-out tests, and immersion tests. SPEEK-WA induces pre-osteoblast functions including initial cell adhesion, proliferation, and osteogenic differentiation in vitro as well as substantially enhanced osseointegration and bone-implant bonding strength in vivo and apatite-forming ability. Although SPEEK-W has a similar surface morphology and chemical composition as SPEEK-WA, its cytocompatibility is inferior due to residual sulfuric acid. Our results reveal that the pre-osteoblast functions, bone growth, and apatite formation on the SPEEK surfaces are affected by many factors, including positive effects introduced by the 3D porous structure and SO₃H groups as well as negative ones due to the low pH environment. Surface functionalization broadens the use of PEEK in orthopedic implants.     

Tuning of the surface biological behavior of poly(L-lactide)-based composites by the incorporation of polyelectrolyte complexes for bone regeneration

Poly(L-lactide)(PLLA)-based composites have been widely used for tissue regeneration. Novel polyelectrolyte complexes (PECs) consisted of carboxymethyl starch sodium (CMS) and chitosan oligosaccharide (COS) was fabricated and evaluated. The results suggested that the CMS/COS-PECs (CC-PECs) distinguished from the original polymers alone, presenting an amorphous structure. Then, the CC-PECs/PLLA composites were prepared by varying the relative amount of CC-PECs in the PLLA-matrix, demonstrated by means of the surface morphology, hydrophilicity, water uptake, in vitro degradability and primary cell responses. The results suggested that the CC-PECs physically attached on the PLLA surface enhanced the formation of the surface seepage network, which could target modification of the surface biological behavior of the materials. The phenomena had been evidenced by the performed tests in respect to hydrophilicity, water uptake and degradation in PBS, which also may provide effective support for cell adhesion and proliferation. Further, the CC-PECs/PLLA surfaces clearly promoted the adhesion and proliferation of MC3T3-E1 cells compared with PLLA materials, indicating excellent cytocompatibility. This study suggested that the CC-PECs/PLLA-50 composite with excellent biological behavior could be a promising candidate for bone repair.     

光固定明胶修饰的聚醚醚酮(PEEK)表面促进细胞增殖及成骨性研究

目的聚醚醚酮(PEEK)具有与骨骼相似的弹性模量,但PEEK作为骨修复材料的应用受到其表面生物惰性及缺乏促成骨性的限制。为了解决这个问题,我们通过表面修饰光固定明胶增强PEEK生物活性。方法我科研团队合成的光固定明胶可通过紫外照射粘附于多种材料表面,并可增强材料的生物相容性。进行SEM、静态水接触角、细胞增殖、细胞形态、碱性磷酸酶分化等表征学及细胞学系统研究。结果研究表明光固定明胶可固定于PEEK表面,改变了PEEK等高分子材料的表面性质。在细胞学研究中,光固定明胶改性后相对于普通PEEK,成骨细胞增殖、伸展、基质分泌及分化能力明显增强。结论通过光固定明胶对PEEK表面进行改性,可明显增强其生物活性,是一种有潜力的骨科内植入物及医疗器械材料。     

The relative influence of the topography and chemistry of TiAl6V4 surfaces on osteoblastic cell behaviour

Proliferation and adhesion of mouse (MC3T3-E1) osteoblastic cells and primary human osteoblastic cells were carried out on Ti6Al4V titanium alloy samples with varied surface roughnesses. Mechanically or manually polished surfaces were prepared to produce respectively non-oriented or oriented residual polishing grooves. Sand-blasted surfaces were prepared using 500 microm or 3 mm alumina particles. Surface roughness parameters showed a negative correlation in comparison to proliferation and adhesion parameters. X-ray microprobe chemical surface microanalysis showed complete disturbance of the surface element composition of the Ti6Al4V alloy following sand-blasting treatment. An AlOx-enriched layer was observed on sample surfaces. This may lead to the suspicion that the concomittant effect of surface roughness amplitude and AlOx surface concentration has an effect on osteoblastic cell proliferation and adhesion. These findings show the significance of chemical surface analysis after any surface treatment of titanium-based implants before any biological use.     

Endowing polyetheretherketone with anti-inflammatory ability and improved osteogenic ability

Abstract

Both osteogenesis and anti-inflammatory bioactive materials play a vital role in the regeneration of skeletal defects. Bone inflammation is hard to cure and can lead to malformation or amputation. The purpose of this study is to use anti-inflammatory drugs to endow polyetheretherketone (PEEK) with the dual ability to achieve anti-inflammatory effects while maintaining favorable biocompatibility. In this experiment, the porous PEEK was immersed in an aspirin (ASP) solution after sulfonation, and the obtained porous PEEK had significantly improved the anti-inflammatory abilities. Additionally, grafting the bone forming peptide (BFP) onto the porous PEEK can distinctly enchance the osteogenesis capability. The effects of the BFP polypeptide on the proliferation of MC3T3-E1 cells and ALP activity, and the effects of aspirin on inflammation were systematically investigated. The modified material showed favorable biocompatibility and osteogenic ability. The results suggest that the combination of the BFP polypeptide with aspirin may lead to a synergetic effect on the stimulation of osteogenesis and on the reduction of inflammation.     

表面矿化修饰煅烧骨/BMP2活性多肽复合MC3T3-E1细胞构建组织工程骨

探讨表面矿化修饰煅烧骨/BMP₂活性多肽复合材料、表面矿化修饰煅烧骨和单纯煅烧骨复合MC3T3-E1细胞构建的组织工程骨在体内的成骨能力。实验分3组,A组：表面矿化修饰煅烧骨/BMP₂活性多肽复合材料,B组：表面矿化修饰煅烧骨,C组：单纯煅烧骨。诱导培养MC3T3-E1细胞,将其分别接种于3组材料,倒置相差显微镜和环境扫描电镜分别观察细胞生长情况。将18只新西兰大白兔随机分成3组,每只大白兔作两侧骶棘肌肌袋模型,然后将3组材料分别植入大白兔骶棘肌内,分别于术后第4、8周各组处死大白兔3只,行组织学观察及新生骨面积测定。通过观察发现MC3T3-E1细胞在3组材料表面生长良好,表面矿化修饰煅烧骨/BMP₂活性多肽复合材料能促进MC3T3-E1细胞在其表面粘附与增殖并能较好地保持细胞的形态。术后第4、8周组织学观察A组材料新生骨明显多于B组,B组多于C组。术后4周和8周新生骨面积测定值A、B、C组分别为（19 712.524±3 782.126）μm²、（28 227.617±2 455.375）μm²,（11 648.507±1 047.221）μm²、（14 592.892±899.532）μm²,（7 986.655±903.487）μm²,（11 254.822±669.508）μm²。表面矿化修饰煅烧骨/BMP₂活性多肽复合材料是一种较理想的骨组织工程复合材料,有望应用于临床。     

miR-132-3p过表达对MC3T3-E1细胞增殖分化的影响

文题释义： miRNA：是一类小的非编码RNA,长度约为22个核苷酸,其主要通过结合靶标mRNA的3'UTR区诱导靶标mRNA降解或抑制其翻译,从而在转录及转录后水平调控相关基因的表达。miRNA在细胞增殖、分化及凋亡等多种生物学活动过程中起着非常重要的调控作用,并且发现它是调控骨组织细胞增殖和分化过程的重要因子之一。 MC3T3-E1细胞：是新生C57BL/6小鼠颅顶骨中分离培养所建立的一株成骨细胞株,它能够展现骨组织中成骨细胞的各个发育阶段和各种生物学特性。作为研究成骨细胞增殖和分化的理想模型,被广泛应用于国内外各种骨组织工程学研究。 背景：机械牵引力能够影响MC3T3-E1细胞的增殖分化过程,并引起细胞内miR-132-3p的差异表达。然而,牵引力是否通过调控miR-132-3p的表达来影响成骨细胞增殖分化仍需进一步研究。 目的：明确12%牵引力作用下MC3T3-E1细胞中成骨分化标志因子及miR-132-3p表达变化,并进一步探讨miR-132-3p对细胞增殖分化的影响。 方法：MC3T3-E1细胞分别加载0%,12%牵张应力,检测应力加载后碱性磷酸酶活性、骨钙蛋白及miR-132-3p mRNA的表达水平;细胞内瞬时转染miR-132-3p模拟物及其阴性对照,qRT-PCR检测转染后碱性磷酸酶、骨钙蛋白、Runt标志转录因子2 mRNA的表达,CCK-8法检测miR-132-3p对细胞增殖能力的影响。 结果与结论：①12%牵张应力作用下,MC3T3-E1细胞中碱性磷酸酶活性、骨钙蛋白mRNA表达水平下调(P < 0.01),miR-132-3p表达水平显著升高(P < 0.05);②细胞内转染miR-132-3p后,miR-132-3p模拟物组成骨分化标志因子碱性磷酸酶、骨钙蛋白、Runt标志转录因子2 mRNA表达水平显著降低(P < 0.05);③相比于阴性对照组,miR-132-3p 模拟物转染24,48,72 h后细胞增殖能力明显降低(P < 0.001),且在转染48 h后降低最明显;④结果说明12%周期性循环牵张应力能够通过过表达miR-132-3p负向调节MC3T3-E1细胞的增殖和成骨分化。 ORCID: 0000-0003-0696-3329(孙芬) 中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

Effect of gamma-ray irradiated poly(L-lactide) on the differentiation of mouse osteoblast-like MC3T3-E1 cells

The purpose of this study was to clarify the effects of gamma-ray irradiated poly(L-lactide) (PLLA) on the proliferation and differentiation of mouse osteoblast-like MC3T3-E1 cells. The PLLA was y-irradiated at the dose of 10, 25 or 50 kGy, and the molecular weight of irradiated PLLA decreased with increasing irradiation dose. The proliferation and differentiation of MC3T3-E1 cells cultured on irradiated PLLA for 2 weeks were evaluated using micromass culture. The y-irradiation of PLLA did not affect the proliferation, but stimulated the differentiation of MC3T3-E1 cells cultured on irradiated PLLA. These results suggested that lower change in the molecular weight of PLLA was responsible for stimulation of the differentiation of MC3T3-E1 cells cultured on irradiated PLLA. Furthermore, the proliferation and calcification of MC3T3-E1 cells cultured in the medium containing low molecular weight PLLA for 2 weeks were evaluated. The low molecular weight PLLA also stimulated the calcification of MC3T3-E1 cells with no effect on the proliferation. The y-irradiation was suitable for PLLA on the differentiation of mouse osteoblasts.