体外诱导微环境对骨髓间充质干细胞成神经分化的影响及分化后的自发逆转现象

目的体外定向诱导大鼠骨髓间充质干细胞(Mesenchymal stem cells,MSCs)成神经分化,并探讨诱导微环境对其分化的影响及分化后的自发逆转现象。方法体外分离培养大鼠MSCs,流式细胞仪检测细胞表面标志。采用改良神经元诱导液[Modified neuronal induction media(MNM)]定向诱导MSCs,免疫荧光检测神经细胞表面标志。观察胎牛血清(FBS)浓度、细胞密度、MNM剂量、新鲜与使用过的MNM等不同诱导微环境对MSCs成神经分化的影响。结果 MSCs经MNM诱导后,6h即可见尼氏体,表达神经元特异性表面标志神经元特异性烯醇化酶(NSE)、巢蛋白(Nestin)和微管相关蛋白-2(MAP-2)。随着诱导微环境的改变,MSCs成神经分化率及神经元表面标志表达亦发生改变,且分化后的神经元样细胞可自发逆转。结论 MSCs能够在MNM微环境中定向成神经分化,但诱导微环境的改变可以从量和质两个层面影响MSCs定向分化。     

大鼠骨髓间充质干细胞向肝样细胞的定向诱导分化

目的 探讨肝细胞生长因子(Hepatocyte growth factor,HGF)和碱性成纤维细胞生长因子(Basic fibroblast growthfactor,bFGF)诱导大鼠骨髓间充质干细胞(Bone marrow mesenchymal stem cells,BM-MSCs)分化为肝样细胞的可行性。方法取SD大鼠股骨骨髓,直接贴壁法分离纯化BM-MSCs,并体外传代,流式细胞术和成骨诱导对其进行鉴定。取第3代BM-MSCs,分为2组:实验组用HGF(20 ng/ml)和bFGF(10 ng/ml)进行诱导,阴性对照组不加诱导剂,倒置显微镜下观察细胞形态变化;RT-PCR法检测诱导后细胞甲胎蛋白(Alpha fetoprotein,AFP)和白蛋白(Albumin,ALB)基因mRNA的转录水平;免疫细胞化学染色法检测诱导后细胞的AFP和ALB蛋白的表达。结果第3代BM-MSCs表型标志和功能特性均符合MSCs的特点。BM-MSCs经HGF和bFGF诱导后呈肝样细胞形态。实验组细胞可检测出AFP和ALB基因mRNA的表达。实验组细胞诱导后第7天,AFP蛋白开始表达,第14天时表达降低,第21天时不表达;ALB于诱导后第14天出现表达,并随诱导时间的延长表达逐渐增加。结论 HGF和bFGF具有体外诱导BM-MSCs向肝样细胞分化的作用。     

大鼠骨髓间充质干细胞向成骨与成脂分化过程中相关基因的表达变化

目的探讨大鼠骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)向成骨与成脂分化过程中相关基因表达的变化。方法采用全贴壁法分离培养大鼠BMSCs,并观察其形态学特征的变化,MTT法检测其生长状况,并绘制生长曲线。分别采用成骨和成脂诱导剂对第4代BMSCs进行诱导分化,应用碱性磷酸酶试剂盒、茜素红和油红O染色液检测其ALP活性、成骨和成脂分化能力;RT-QPCR检测诱导0、7、14和21 d的成骨分化相关基因Runt相关转录因子2(Runx2)、骨钙素(osteocalcin,OCN)、碱性磷酸酶(ALP)及成脂分化相关基因过氧化物酶体增殖物激活受体γ(peroxidase proliferator activated receptor gamma,PPARγ)和脂肪酸结合蛋白(FABP4)的表达变化。结果全骨髓贴壁法能成功分离培养BMSCs,传代细胞生长增殖迅速,以长梭形细胞生长为主,细胞生长曲线呈S形。第4代BMSCs分别经成骨和成脂诱导剂诱导后,ALP、茜素红和油红O染色均呈阳性;诱导7、14和21 d后,Runx2、OCN、ALP、PPARγ和FABP4基因mRNA的表达量均显著高于0 d(P0.05);成骨分化过程中,Runx2和ALP在第7天时表达量最高,之后呈下降趋势,OCN的表达量呈稳定上升趋势;成脂分化过程中,PPARγ在第7天时表达量最高,FABP4始终高表达。结论 BMSCs具有易于体外分离培养、扩增和经诱导后具有多向分化潜能等特点,成骨和成脂分化相关基因的表达量随诱导时间延长而变化,呈明显的时序性表达差异,提示分别在成骨与成脂分化过程中起重要调控作用,为BMSCs在骨、细胞和基因等工程中的机制研究提供了实验依据。     

骨髓间充质干细胞对海藻酸钙胶珠内神经干细胞增殖与分化的作用

神经干细胞(neural stem cells,NSCs)移植治疗神经损伤被认为是具有潜在应用价值的手段,但其来源困难;骨髓间充质干细胞(bone marrow mesenchymal stem cells,BMSCs)以其所具有的诸多优点,为神经损伤的治疗提供了一个新的思路。而BMSCs是否是通过作用于内源性的NSCs来促进神经修复,仍存在着争议。今采用海藻酸钙胶珠将NSCs包囊培养至一定大小的神经球后,再与BMSCs进行共培养,考察BMSCs对生长在海藻酸钙胶珠内的NSCs增殖与分化的作用,探讨BMSCs移植治疗神经疾病与损伤的作用机理。共培养过程中观察神经球结构的变化;共培养结束后计算NSCs的增殖倍数,对增殖条件下共培养的NSCs表型和多向分化潜能进行免疫荧光染色鉴定;对分化条件下共培养的NSCs向不同神经细胞分化的能力进行流式细胞仪检测。结果表明,BMSCs可使生长于支架内的NSCs迁出细胞球,对NSCs的增殖没有明显影响;但能够明显影响NSCs的分化,使其向少突胶质细胞分化的能力增加3倍,向星形胶质细胞分化的能力减弱1倍,而向神经元细胞分化的能力没有明显变化。BMSCs有可能是通过分泌某些因子增加了NSCs迁移及向少突胶质细胞分化的能力,从而促进神经损伤的修复。     

骨髓间充质干细胞向视网膜神经节样细胞的分化

目的探讨乳鼠视网膜细胞条件分化液诱导骨髓间充质干细胞(BMSCs)的神经分化情况,以期为视网膜退行性疾病提供治疗方案。方法体外分离培养Wistar大鼠乳鼠BMSCs,观察BMSCs的增殖情况并进行鉴定;制备乳鼠视网膜细胞条件分化液,以其诱导BMSCs,观察BMSCs的神经分化情况,并行免疫组化鉴定。结果体外培养获得了较纯的BMSCs;在乳鼠视网膜细胞条件分化液的环境中,诱导后72h,BMSCs胞体收缩成锥形或球形,细胞突起变细、变长,呈神经细胞的典型形态;免疫组化结果显示,部分细胞呈神经元特异性烯醇化酶(NSE)、巢蛋白(nestin)和Thy1.1阳性反应。结论乳鼠视网膜细胞条件分化液可诱导BMSCs分化成视网膜神经节样细胞。     

成骨生长肽对鼠骨髓间充质干细胞增殖及成骨分化的作用

目的 探讨成骨生长肽(osteogenic growth peptide,OGP)对鼠骨髓间充质干细胞(mouse bone marrow mesenchymal stem cell,mBMSC)增殖及成骨分化的作用及其分子机制.方法 采用乳鼠骨片法分离mBMSC,流式细胞术测定mBMSC表面特征性分子.以10-5 m...     

去上皮羊膜及其浸提液体外诱导骨髓间充质干细胞的分化

目的观察去上皮羊膜及其浸提液体外诱导骨髓间充质干细胞(Bone marrow mesenchymal stem cells,BMSCs)向上皮细胞的分化,并探讨其机制。方法从胎儿四肢长骨分离BMSCs,扩增后采用流式细胞术分析第3代(P3)细胞表面抗原(CD29、CD34、CD71和HLA-DR)的表达,并用4,6-乙酰基-2-苯基吲哚(DAPI)标记第4代BMSCs(P4-BMSCs)。机械法去除正常胎盘羊膜上皮,制成去上皮羊膜,并制备去上皮羊膜浸提液。将DAPI标记的BMSCs接种于羊膜上,设加或不加表皮细胞生长因子(Epidermal growth factor,EGF)、类胰岛素1号生长因子(Insulin-like growth factor 1,IGF-1)、羊膜浸提液诱导组及细胞爬片对照组,体外诱导培养后,采用免疫荧光组织(细胞)化学染色学法检测各组细胞角蛋白(Cytokeratin,CK)、EGF-R和IGF-1-R的表达,并于诱导后第10天计算CK阳性细胞率。结果原代BMSCs呈典型旋涡状生长,P3细胞表达CD29和CD71,不表达CD34和HLA-DR。羊膜组和细胞爬片组BMSCs在加入EGF或IGF-1诱导后,表达EGF-R和IGF-1-R的时间较未加生长因子的对照组提前2～4 d,表达CK的时间提前2～6 d,单用羊膜组或羊膜浸提液组的表达时间差异无统计学意义(P>0.05);诱导第10天,单用羊膜或羊膜浸提液诱导组的CK阳性细胞表达率明显高于细胞爬片对照组(P<0.05);羊膜与EGF、IGF-1联合诱导组高于单用羊膜组(P<0.05);EGF诱导组高于IGF-1诱导组(P<0.05)。结论羊膜及羊膜浸提液、外源性EGF和IGF-1在体外均可诱导BMSCs向上皮细胞分化,羊膜可能主要通过其所含的细胞因子诱导BMSCs向上皮分化。     

cAMP-PKA-CREB信号通路在骨形态发生蛋白9诱导小鼠间充质干细胞成骨分化中的作用

目的探讨cAMP-PKA-CREB信号通路在骨形态发生蛋白9(bone morphogenetic protein 9,BMP9)诱导小鼠间充质干细胞(mesenchymal stem cells,MSCs)C3H10T1/2成骨分化过程中的作用及其机制。方法将C3H10T1/2细胞分别加入不同浓度的cAMP-PKA-CREB信号通路抑制剂H89(1、2.5、5和10μmol/L),检测其对碱性磷酸酶(alkaline phosphatase,ALP)活性的影响;通过ALP定量和钙盐沉积试验分别检测H89对BMP9诱导C3H10T1/2细胞早期和晚期成骨分化的影响;经Western blot法检测H89对C3H10T1/2细胞中磷酸化CREB、骨钙素(Osteocalcin,OCN)和成骨关键转录因子Runx2表达水平的影响;通过Wentern blot及荧光素酶活性的检测,观察H89对经典信号通路BMPs-smad1/5/8的影响。结果随着H89浓度的增加,对BMP9诱导的C3H10T1/2细胞ALP的抑制作用明显增强(P0.05),且呈剂量依赖性;ALP定量和钙盐沉积试验结果表明,H89可明显抑制BMP9诱导的C3H10T1/2细胞早期及晚期成骨分化;H89可显著抑制BMP9诱导的C3H10T1/2细胞中磷酸化CREB、OCN及Runx2蛋白的表达(P0.05),与AdBMP9组比较,H89对经典BMPs-smad1/5/8信号通路无明显影响(P0.05)。结论阻断cAMP-PKA-CREB信号通路可抑制BMP9诱导的MSCs C3H10T1/2的成骨分化,为BMP9的临床应用奠定了理论基础。     

大鼠骨髓间充质干细胞的体外分离培养与鉴定

目的建立大鼠骨髓间充质干细胞(Mesenchymal stem cells,MSCs)体外分离培养及鉴定的方法 ,为MSCs的系列研究奠定基础。方法采用全骨髓直接贴壁筛选法分离培养MSCs并传代,倒置相差显微镜下观察细胞形态,以MTT法检测细胞增殖水平并绘制生长曲线。取第3代MSCs,流式细胞术检测细胞周期和细胞表型,应用成骨细胞诱导液和脂肪样细胞诱导液诱导MSCs定向分化,鉴定其分化能力。结果全骨髓细胞培养5d,镜下可见贴壁细胞增殖明显,细胞形态较均一,大部分呈梭形,7d左右可传代,经2～3次传代后细胞呈单一梭形的成纤维样细胞,即MSCs;细胞生长曲线呈S形;经流式细胞仪检测,MSCs细胞76.01%处于G0/G1期,7.13%处于G2/M期,16.86%处于S期;MSCs表面不表达CD34;在特定诱导液作用下,MSCs可分别向成骨样细胞及脂肪样细胞分化。结论已成功建立了分离培养及鉴定MSCs的方法 ,可用来评价体外培养的MSCs。     

β-catenin对骨形态发生蛋白9诱导间充质干细胞成骨分化的影响

目的探讨经典Wnt信号通路关键节点β-catenin对骨形态发生蛋白9(bone morphogenetic protein 9,BMP9)诱导间充质干细胞(mesenchymal stem cells,MSCs)成骨分化的影响。方法用重组腺病毒介导BMP9在C3H10T1/2细胞中过表达,联用β-catenin重组腺病毒上调β-catenin的表达,并通过RNA干扰抑制β-catenin的表达。分析C3H10T1/2细胞碱性磷酸酶(alkaline phosphatase,ALP)活性的变化;RT-PCR检测细胞成骨分化相关基因骨桥蛋白(osteopontin,OPN)和骨钙蛋白(osteocalcin,OC)基因mRNA的转录水平;茜素红S染色检测细胞的钙盐沉积。结果 BMP9单独作用能诱导C3H10T1/2细胞向成骨方向分化,并增强细胞ALP活性;单独的β-catenin无成骨诱导作用,但可剂量依赖性地增强BMP9诱导的C3H10T1/2细胞的ALP活性,并促进BMP9诱导的细胞OPN和OC基因mRNA的转录水平及钙盐沉积;抑制β-catenin表达可显著降低BMP9诱导的C3H1OT1/2细胞的ALP活性(P0.05),下调OPN和OC基因mRNA的转录水平,并抑制钙盐沉积。结论经典Wnt信号通路可能通过β-catenin协同BMP9诱导C3H10T1/2细胞成骨分化,且BMP9诱导的成骨分化可能需要通过Wnt/β-catenin途径来实现。     

旋转壁式生物反应器中微囊化骨髓间充质干细胞支持造血干/祖细胞的体外扩增

为了构建一种新型的造血干细胞和基质细胞动态共培养体系,脐带血单个核细胞和包埋有兔骨髓间充质干细胞的海藻酸钠-壳聚糖-海藻酸钠(alginate-chitosan-alginate, ACA)微胶囊在旋转壁式生物反应器(rotating wall vessel, RWV)中进行了7d动态悬浮共培养.培养液不含血清,补充多种生长因子(SCF 50ng·mL-1,FL 50ng·mL-1,TPO 50ng·mL-1及IL-325ng·mL-1).每24h进行总有核细胞计数,并测量培养液的pH和渗透压,在0h、72h和168h进行流式CD34 细胞分析以及集落形成能力检验.结果表明在RWV动态共培养过程中,培养液的pH保持在7.2~7.4,渗透压保持在280~310mmOsmol·kg-1,均适合造血干/祖细胞的体外扩增.经过7d的无血清动态共培养,总有核细胞、CD34 细胞以及混合集落(colony-forming units in culture, CFU-Cs)分别扩增了107.05±6.08,26.52±1.5和19.2±3.18倍.这种新型的动态微囊化共培养体系支持了造血干/祖细胞的大规模体外扩增,基质细胞抑制了造血干/祖细胞的分化,微胶囊对造血细胞和基质细胞进行了免疫隔离,RWV则为细胞和微胶囊提供了优良的低剪切力的悬浮培养环境.     

Receptor-Targeted,Magneto-Mechanical Stimulation of Osteogenic Differentiation of Human Bone Marrow-Derived Mesenchymal Stem Cells

Mechanical cues are employed to promote stem cell differentiation and functional tissue formation in tissue engineering and regenerative medicine. We have developed a Magnetic Force Bioreactor (MFB) that delivers highly targeted local forces to cells at a pico-newton level, utilizing magnetic micro- and nano-particles to target cell surface receptors. In this study, we investigated the effects of magnetically targeting and actuating specific two mechanical-sensitive cell membrane receptors—platelet-derived growth factor receptor α (PDGFRα) and integrin α_νβ₃. It was found that a higher mineral-to-matrix ratio was obtained after three weeks of magneto-mechanical stimulation coupled with osteogenic medium culture by initially targeting PDGFRα compared with targeting integrin α_νβ₃ and non-treated controls. Moreover, different initiation sites caused a differentiated response profile when using a 2-day-lagged magneto-mechanical stimulation over culture periods of 7 and 12 days). However, both resulted in statistically higher osteogenic marker genes expression compared with immediate magneto-mechanical stimulation. These results provide insights into important parameters for designing appropriate protocols for ex vivo induced bone formation via magneto-mechanical actuation.     

Cartilage Oligomeric Matrix Protein Gene Multilayers Inhibit Osteogenic Differentiation and Promote Chondrogenic Differentiation of Mesenchymal Stem Cells

There are still many challenges to acquire the optimal integration of biomedical materials with the surrounding tissues. Gene coatings on the surface of biomaterials may offer an effective approach to solve the problem. In order to investigate the gene multilayers mediated differentiation of mesenchymal stem cells (MSCs), gene functionalized films of hyaluronic acid (HA) and lipid-DNA complex (LDc) encoding cartilage oligomeric matrix protein (COMP) were constructed in this study via the layer-by-layer self-assembly technique. Characterizations of the HA/DNA multilayered films indicated the successful build-up process. Cells could be directly transfected by gene films and a higher expression could be obtained with the increasing bilayer number. The multilayered films were stable for a long period and DNA could be easily released in an enzymatic condition. Real-time polymerase chain reaction (RT-PCR) assay presented significantly higher (p < 0.01) COMP expression of MSCs cultured with HA/COMP multilayered films. Compared with control groups, the osteogenic gene expression levels of MSCs with HA/COMP multilayered films were down-regulated while the chondrogenic gene expression levels were up-regulated. Similarly, the alkaline phosphatase (ALP) staining and Alizarin red S staining of MSCs with HA/COMP films were weakened while the alcian blue staining was enhanced. These results demonstrated that HA/COMP multilayered films could inhibit osteogenic differentiation and promote chondrogenic differentiation of MSCs, which might provide new insight for physiological ligament-bone healing.     

Hypoxia Suppresses Spontaneous Mineralization and Osteogenic Differentiation of Mesenchymal Stem Cells via IGFBP3 Up-Regulation

Hypoxia has diverse stimulatory effects on human adipose-derived stem cells (ASCs). In the present study, we investigated whether hypoxic culture conditions (2% O₂) suppress spontaneous mineralization and osteogenic differentiation of ASCs. We also investigated signaling pathways and molecular mechanisms involved in this process. We found that hypoxia suppressed spontaneous mineralization and osteogenic differentiation of ASCs, and up-regulated mRNA and protein expression of Insulin-like growth factor binding proteins (IGFBPs) in ASCs. Although treatment with recombinant IGFBPs did not affect osteogenic differentiation of ASCs, siRNA-mediated inhibition of IGFBP3 attenuated hypoxia-suppressed osteogenic differentiation of ASCs. In contrast, overexpression of IGFBP3 via lentiviral vectors inhibited ASC osteogenic differentiation. These results indicate that hypoxia suppresses spontaneous mineralization and osteogenic differentiation of ASCs via intracellular IGFBP3 up-regulation. We determined that reactive oxygen species (ROS) generation followed by activation of the MAPK and PI3K/Akt pathways play pivotal roles in IGFBP3 expression under hypoxia. For example, ROS scavengers and inhibitors for MAPK and PI3K/Akt pathways attenuated the hypoxia-induced IGFBP3 expression. Inhibition of Elk1 and NF-κB through siRNA transfection also led to down-regulation of IGFBP3 mRNA expression. We next addressed the proliferative potential of ASCs with overexpressed IGFBP3, but IGFBP3 overexpression reduced the proliferation of ASCs. In addition, hypoxia reduced the osteogenic differentiation of bone marrow-derived clonal mesenchymal stem cells. Collectively, our results indicate that hypoxia suppresses the osteogenic differentiation of mesenchymal stem cells via IGFBP3 up-regulation.     

Mesenchymal Stem Cells and Induced Pluripotent Stem Cells as Therapies for Multiple Sclerosis

Multiple sclerosis (MS) is a chronic, autoimmune, inflammatory demyelinating disorder of the central nervous system that leads to permanent neurological deficits. Current MS treatment regimens are insufficient to treat the irreversible neurological disabilities. Tremendous progress in the experimental and clinical applications of cell-based therapies has recognized stem cells as potential candidates for regenerative therapy for many neurodegenerative disorders including MS. Mesenchymal stem cells (MSC) and induced pluripotent stem cell (iPSCs) derived precursor cells can modulate the autoimmune response in the central nervous system (CNS) and promote endogenous remyelination and repair process in animal models. This review highlights studies involving the immunomodulatory and regenerative effects of mesenchymal stem cells and iPSCs derived cells in animal models, and their translation into immunomodulatory and neuroregenerative treatment strategies for MS.     

骨髓间充质干细胞对电离辐射诱发的小鼠胸腺瘤的抑制作用

目的观察骨髓间充质干细胞(MSCs)对电离辐射诱发的小鼠胸腺瘤的抑制作用。方法采用经典Kaplan法复制电离辐射诱发的小鼠胸腺瘤模型。应用全骨髓贴壁法分离培养C57BL/6小鼠MSCs,DAPI标记,经尾静脉注入荷瘤小鼠后,分别于1、5、10d处死小鼠,取胸腺组织,激光共聚焦显微镜下观察MSCs在胸腺瘤组织中的定位;第1次全身大剂量照射后6个月取胸腺组织,HE染色观察胸腺组织的病理变化,并判断成瘤情况。结果激光共聚焦显微镜下观察可见,MSCs经尾静脉输注后可迁徙至小鼠胸腺组织内;病理观察显示,胸腺组织皮髓质结构清楚,淋巴样肿瘤细胞较少,细胞形态、大小不一,偶见核分裂象;MSCs输注使辐射诱导的胸腺瘤成瘤率由57.00%±9.78%降低至37.50%±7.55%。结论已成功建立辐射诱发的小鼠胸腺瘤模型;输注的MSCs可迁徙至胸腺组织中,并降低胸腺瘤的成瘤率。     

人羊膜间充质干细胞在微载体动态培养体系中的扩增和成骨诱导分化

人羊膜间充质干细胞(hAMSCs)作为一种多潜能干细胞有望应用于骨组织工程.但是,传统的静态培养和诱导方法并不利于间充质干细胞的体外扩增和成骨分化.实验通过考察和比较在孔板中静态及微载体动态培养条件下hAMSCs的扩增与成骨诱导,以建立集间充质干细胞增殖和成骨分化诱导为一体的动态培养体系.将hAMSCs接种到Cytod...