衰老的骨髓间充质干细胞生物学行为及其意义

骨髓间充质干细胞(BMSCs)是骨髓中除造血干细胞外的另一类具有高度可塑性的细胞群体,可从体内器官组织中分离出且具备在体外培养、诱导和扩增等特性,其在基因治疗、细胞治疗及组织工程等领域具有广泛的临床应用前景.近年来,BMSCs被越来越多地应用于自体移植进行细胞治疗和组织工程中,但是并不是所有的BMSCs都适用于自体移植.BMSCs会出现生物衰老,生物衰老的BMSCs分为年龄所致衰老和连续传代所致衰老.衰老的BMSCs因其生物学行为发生改变,其自体移植的成功率也随之降低.结合近年来有关BMSCs的研究进展,对衰老的BMSCs的生物学行为进行综述.     

Continuous stimulation with differentiation factors is necessary to enhance osteogenic differentiation of human mesenchymal stem cells in-vitro

Bone defect treatment belongs to the most challenging fields in orthopedic surgery and requires the well-coordinated application of mesenchymal stem cells (MSC) and differentiation factors. MSC isolated from reaming material (RMSC) and iliac crest (BMSC) in combination with bone morphogenetic protein-7 (BMP-7) and insulin-like growth factor-1 (IGF-1) have been used. The short half-life of both factors limit their applications: a burst release of the factor can probably not induce sustainable differentiation. We stimulated MSC in osteogenic differentiation medium with three different concentrations of BMP-7 or IGF-1: Group A was stimulated continuously, group B for 24?h and group C remained without any stimulation. Osteogenic differentiation was measured after seven and 14?days by alizarin red staining and alkaline phosphatase (ALP) activity. Continuous stimulation led to higher levels of osteogenic differentiation than short-term stimulation. This could lead to a reconsideration of established application forms for differentiation factors, aiming to provide a more sustained release.     

Resistance of bone marrow mesenchymal stem cells in a stressed environment - Comparison with osteocyte cells

Introduction: Recently, the efficacy of mesenchymal stem cells (MSCs) mediated by their tissue repair and anti-inflammatory actions in the prevention and therapy of various disorders has been reported. In this research, our attention was focused specifically on the prevention and therapy of glucocorticoid-induced osteonecrosis. We investigated the stress resistance of MSC against glucocorticoid administration and hypoxic stress, which are factors known to induce osteocytic cell death.Materials and Methods: Mouse bone cells (MLO-Y4) and bone-marrow derived mouse MSCs were exposed to dexamethasone (Dex), hypoxia of 1% oxygen or both in vitro. Mitochondrial membrane potentials were estimated by mitochondria labeling with a cell-permeant probe (Mito tracker red); expression of these apoptosis-inducing molecules, oxidative stress marker (8-hydroxy-2''-deoxyguanosine), caspase-3, -9, and two apoptosis-inhibiting molecules, energy-producing ATP synthase (ATP5A) and X-linked inhibitor of apoptosis protein (XIAP), were analyzed by both immunofluorescence and western blot.Results: With exposure to either dexamethasone or hypoxia, MLO-Y4 showed reduced mitochondrial membrane potential, ATP5A and upregulation of 8-OHdG, cleaved caspases and XIAP. Those changes were significantly enhanced by treatment with dexamethasone plus hypoxia. In MSCs, however, mitochondrial membrane potentials were preserved, while no significant changes in the pro-apoptosis or anti-apoptosis molecules analyzed were found even with exposure to both dexamethasone and hypoxia. No such effects induced by treatment with dexamethasone, hypoxia, or both were demonstrated in MSCs at all.Discussion: In osteocyte cells subjected to the double stresses of glucocorticoid administration and a hypoxic environment osteocytic cell death was mediated via mitochondria. In contrast, MSC subjected to the same stressors showed preservation of mitochondrial function and reduced oxidative stress. Accordingly, even under conditions sufficiently stressful to cause the osteocytic cell death in vivo, it was thought that the function of MSC could be preserved, suggesting that in the case of osteonecrosis preventative and therapeutic strategies incorporating their intraosseous implantation may be promising.     

An assessment of bone marrow mesenchymal stem cell and human articular cartilage derived chondroprogenitor cocultures vs. monocultures

BackgroundCell based therapy in cartilage repair predominantly involves the use of chondrocytes and mesenchymal stromal cells (MSC). Co-culture systems, due to their probable synergistic effect on enhancement of functional chondrogenesis and reduction in terminal differentiation have also been attempted. Chondroprogenitors, derived from articular cartilage and regarded as MSCs, have recently garnered interest for consideration in cartilage regeneration to overcome limitations associated with use of conventional cell types. The aim of this study was to assess whether co-culturing bone marrow (BM)-MSCs and chondroprogenitors at different ratios would yield superior results in terms of surface marker expression, gene expression and chondrogenic potential.MethodsHuman BM-MSCs and chondroprogenitors obtained from three osteoarthritic knee joints and subjected to monolayer expansion and pellet cultures (10,000 cells/cm²) as five test groups containing either monocultures or co-cultures (MSC: chondroprogenitors) at three different ratios (75:25, 50:50 and 25:75) were utilized.ResultsData analysis revealed that all groups exhibited a high expression of CD166, CD29 and CD49e. With regard to gene expression, high expression of SOX9, Aggrecan and Collagen type I; a moderate expression of Collagen type X and RUNX2; with a low expression of Collagen type II was seen. Analysis of pellet culture revealed that chondroprogenitor monoculture and chondroprogenitor dominant coculture, exhibited a subjectively larger pellet size with higher deposition of Collagen type II and glycosaminoglycan.ConclusionIn conclusion, this study is suggestive of chondroprogenitor monoculture superiority over MSCs, either in isolation or in a coculture system and proposes further analysis of chondroprogenitors for cartilage repair.     

达沙替尼对人骨髓间充质干细胞生物学特性的影响

目的:在体外探索达沙替尼对人骨髓来源间充质干细胞(hBMSCs)的活力、迁移、细胞周期和凋亡的影响以及潜在的信号通路,以评估达沙替尼在临床应用中对骨髓造血微环境的影响。方法:CCK-8法检测细胞活力;划痕实验检测细胞迁移;流式细胞术检测细胞周期和凋亡;同时采用吖啶橙/溴化乙啶法检测细胞凋亡;酶联免疫吸附实验检测细胞转化生长因子β1(TGF-β1)和肿瘤坏死因子α(TNF-α)的分泌情况;Western blot检测蛋白激酶B(Akt)蛋白的表达和磷酸化以及cleaved caspase-3的蛋白水平。结果:与对照组相比,达沙替尼(1~10nmol/L)抑制hBMSCs的活力和迁移;在随后的实验中使用的浓度为7 nmol/L。达沙替尼促进细胞凋亡,并使更多细胞的周期阻滞在G_1期。此外,hBMSCs TGF-β1和TNF-α的分泌量显著增加。7 nmol/L达沙替尼组cleaved caspase-3的蛋白水平增加,胞内Akt的蛋白量下调且其磷酸化受到抑制。结论:达沙替尼以浓度依赖性的方式抑制hBMSCs的活力和迁移,并促进TGF-β1和TNF-α的分泌,诱导细胞G_1期阻滞和凋亡;达沙替尼可能通过影响胞内Akt蛋白的表达和磷酸化调控上述细胞学行为。     

骨髓间充质干细胞向肝细胞转化的研究进展

骨髓间充质干细胞具有自我更新和多向分化潜能的特性,在体内特定的微环境中可向肝前体细胞及成熟肝细胞转化,明显改善肝功能;在体外通过肝细胞生长因子等诱导作用可转化为肝细胞样细胞,有望成为肝细胞移植或生物人工肝支持系统的新型种子细胞。就骨髓间充质干细胞向肝细胞的转化研究进行了阐述。     

Characteristics of human bone marrow mesenchymal stem cells isolated by immunomagnetic selection

Immunophenotype of human bone marrow mesenchymal stem cells was studied after several culturing passages and after cryopreservation. Immunocytochemical analysis showed that bone marrow mesenchymal stem cells acquired homogeneity during in vitro culturing, but initially contained heterogeneous populations. __________ Translated from Kletochnye Tekhnologii v Biologii i Meditsine, No. 1, pp. 3–7, January, 2006     

New depowdering-friendly designs for three-dimensional printing of calcium phosphate bone substitutes

Powder-based three-dimensional printing (3DP) is a versatile method that allows creating synthetic calcium phosphate (CaP) scaffolds of complex shapes and structures. However, one major drawback is the difficulty of removing all remnants of loose powder from the printed scaffolds, the so-called depowdering step. In this study, a new design approach was proposed to solve this problem. Specifically, the design of the printed scaffolds consisted of a cage with windows large enough to enable depowdering while still trapping loose fillers placed inside the cage. To demonstrate the potential of this new approach, two filler geometries were used: sandglass and cheese segment. The distance between the fillers was varied and they were either glued to the cage or free to move after successful depowdering. Depowdering efficiency was quantified by microstructural morphometry. The results showed that the use of mobile fillers significantly improved depowdering. Based on this study, large 3DP scaffolds can be realized, which might be a step towards a broader clinical use of 3D printed CaP scaffolds.     

煅烧骨/壳聚糖复合材料促进SD大鼠骨髓间充质干细胞的成骨分化

背景:课题组前期研究已经证实煅烧骨/壳聚糖复合材料的微观结构与自然骨组织相似,安全无毒,抗压强度良好,并且能够促进成骨细胞的增殖及黏附,因此继续研究其对骨髓间充质干细胞成骨分化的作用具有重要意义。目的:探讨煅烧骨/壳聚糖复合材料对骨髓间充质干细胞成骨分化的影响。方法:将煅烧骨/壳聚糖复合材料与SD大鼠骨髓间充质干细胞体外共培养并进行成骨诱导,成骨诱导1,2,3周时,采用实时荧光定量PCR检测成骨分化相关基因的表达。结果与结论:煅烧骨/壳聚糖复合材料能促进骨髓间充质干细胞的增殖黏附,并促进成骨相关基因碱性磷酸酶、Ⅰ型胶原、骨钙素的表达,具有诱导骨髓间充质干细胞成骨分化的作用。     

Enhancing epithelial engraftment of rat mesenchymal stem cells restores epithelial barrier integrity

The cellular origin, in vivo function and fate of donor bone marrow‐derived cells residing in the recipient intestinal epithelial cells, pericryptal myofibroblasts or endothelial cells remain obscure. Although ‘immunoprivileged’ mesenchymal stem cells (MSCs) are prime candidates for cell‐ and gene‐based therapy, their precise role in colitis remains largely undetermined. Using a dextran sulphate sodium (DSS) colitis with busulphan (BU)‐induced hypoplastic marrow model, we examined the therapeutic effects of MSC transplantation, focusing on the role of MSCs as both cell providers and immunomodulators. Donor‐derived MSCs were detected by eGFP immunofluorescence and fluorescence in situ hybridization for Y‐chromosome (Y‐FISH) analysis. Western blot analysis of apical‐most tight junction proteins was performed with antibodies against claudin‐2, ‐7, ‐8, ‐12, ‐13, ‐15 and ZO‐1. Cytokine and cell cycle profiles were analysed by semi‐quantitative RT‐PCR and flow cytometry. Susceptibility to DSS colitis was significantly increased by co‐existing BU‐induced bone marrow hypoplasia and this increase was significantly reduced by enhancing epithelial engraftment of MSCs, an effect depending on restoring epithelial barrier integrity rather than inhibiting host immune responses. We provide evidence that implicates MSCs in maintaining epithelial barrier function by reassembling apical‐most tight junction proteins, claudins. The therapeutic efficacy of extrinsic MSCs depends on enhancing epithelial engraftment in damaged crypts by busulphan conditioning. Such a role for the MSC‐derived intestinal cells in colitis therapy merits further examination and may offer a promising new treatment for inflammatory bowel disease (IBD). Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

CaMKII plays a part in the chondrogenesis of bone marrow-derived mesenchymal stem cells

Aims: The purpose of the study is to observe the functions of calcium/calmodulin dependent protein kinase II (CaMKII) in the induced chondrogenic differentiation of bone marrow derived mesenchymal stem cells (BMSCs). Methods: BMSCs was in vitro isolated and cultured for induced chondrogenesis. Western blot was used to ascertain the expression of CaMKII and phosphorylated CaMKII (PCaMKII, activatory CaMKII) in chondrogenic induced BMSCs. MTT method was utilized to observe the impact of CaMKII on the proliferation of BMSCs. The generation of cartilage matrix in BMSCs cells was detected by toluidine blue staining. The levels of cartilage marker genes COL2A1, Aggrecan and SOX9 in BMSCs were gained by real-time fluorescence quantitative polymerase chain reaction (RT-QPCR). Finally, BMSCs proliferation, cartilage matrix generation and the changes of COL2A1, Aggrecan and SOX9 were surveyed after CaMKII being blocked by CaMKII inhibitor KN93. Results: Expression of CaMKII and PCaMKII could be found in chondrogenic induced BMSCs. CaMKII had no significant influence on BMSCs proliferation, but the toluidine blue staining was obviously lighter, indicating a significant decline in the expression of COL2A1, Aggrecan and SOX9. Conclusion: As one of the factors influencing the chondrogenic capacity of BMSCs, CaMKII does not impact on BMSCs proliferation, but it can inhibit the chondrogenic ability of BMSCs by influencing its differentiation.     

成人骨髓间充质干细胞对造血干细胞体外增殖的影响

目的研究骨髓间充质干细胞（MSC）对脐带血（CB）CD34^＋细胞体外增殖和造血重建能力的影响。方法取人骨髓单个核细胞贴壁培养．梭形细胞完全融合后传代，用流式细胞仪检测免疫表型；将CBCD34^＋细胞接种到MSC或其他培养液中．比较不同培养条件对造血干细胞扩增能力、集落形成能力及黏附分子表达的影响。结果在加入IL-3的培养体系中．在MSC和细胞因子作用下，CD34^＋细胞扩增7d和14d后，有核细胞（NC）、CD34^＋细胞和CDl33^＋细胞数，实验组均显著多于对照组。CD34＋细胞在未加入IL-3的培养体系中培养8d后，实验组NC、CD34^＋细胞、CD34^＋CD38-细胞和造血祖细胞集落扩增倍数均显著高于对照组。扩增后CD34^＋细胞的ALCAM、VLA-α4、VLA-α5、VLA-β1、HCAM、PECAM和LFA-1表达较扩增前无显著变化。结论MSC可为造血干细胞（HSC）体外扩增提供适宜的微环境，有助于CD34^＋细胞体外增殖并抑制HSC分化，保持其造血重建潜能和归巢能力。     

Ectopic osteogenesis of hBMP-2 gene-transduced human bone mesenchymal stem cells/BCB

We determined the feasibility of using scaffolds of adenoviral human BMP2 gene (AdBMP2)-modified human bone marrow mesenchymal stem cells (hBMSCs) and antigen-free bovine cancellous bone (BCB) to construct bone tissue. hMSCs were infected with AdBMP-2. Expression of BMP-2 and alkaline phosphatase confirmed successful secretion of active BMP-2. The osteogenic capability of a composite of AdBMP2-modified hMSCs with BCB was evaluated in athymic mice (group A). BCB (group B), hMSCs/BCB (group C), adenoviral β‐galactosidase genes (Adβgal)-transfected hMSCs/BCB (group D) were controls. Formation of bone tissue was assessed by histological methods 4 weeks and 8 weeks after implantation. Implanted cells were identified by human Y-chromosome-specific fluorescence in-situ hybridization (FISH). hMSCs differentiated into osteogenic cells, and bone formation was observed. Obvious bone formation was not noted at any time point in control groups. We hypothesize that the described method is a promising method for bone regeneration.     

胶原模拟多肽-PEG杂化水凝胶及用于兔骨髓间充质干细胞的三维培养

目的 构建一种模拟细胞外基质的胶原模拟多肽-聚乙二醇(PEG)杂化水凝胶并应用于兔骨髓间充质干细胞(rBMSCs)的三维(3D)培养.方法 利用胶原模拟多肽末端的半胱氨酸与马来酰亚胺修饰的多臂PEG偶联形成杂化水凝胶,圆二色谱表征胶原模拟多肽的三螺旋结构及其热稳定性,流变学检测和扫描电镜观察研究杂化水凝胶的成胶过程、机械强度及水凝胶内部结构.将rBMSCs包埋于杂化水凝胶中进行3D培养,检测水凝胶的细胞相容性及其对rBMSCs分化的影响.结果 胶原模拟多肽能自发形成天然胶原的三螺旋结构,其热变性温度为49.4℃.胶原模拟多肽-PEG杂化水凝胶成胶迅速,内部呈现多孔的网络状纤维结构;杂化水凝胶3D培养rBMSCs 24 h后,绝大部分细胞保持存活状态,基因表达分析结果显示该水凝胶体系构建的3D培养环境能影响rBMSCs的分化.结论 胶原模拟多肽-PEG杂化水凝胶制备条件温和,具有良好的机械强度和细胞相容性,有利于rBMSCs的软骨分化.     

骨髓源性神经干细胞去甲肾上腺素神经递质变化的实验研究

目的研究骨髓源性神经干细胞在体外培养及诱导分化条件下能否分泌去甲肾上腺素(NE).方法分离兔骨髓基质细胞(BMSCs),在体外应用神经干细胞培养液和诱导分化因子使其分化为神经干细胞及神经元样细胞,采用免疫细胞化学方法进行鉴定;应用高效液相色谱法(HPLC)检测其NE的含量.结果BMSCs培养7～14 d免疫细胞化学鉴定Nestin抗原阳性;培养20 d可见长突起神经元样细胞,神经核蛋白(NeuN)呈阳性表达;HPLC检测神经干细胞培养液及L-02肝细胞等阴性对照组及BMSCs(0～5 d)组未检测到NE,骨髓源性神经干细胞(培养7 d、14 d)及神经元样细胞(培养20d)均可检测到NE.随着培养天数的增加,所含的NE浓度也逐渐增加(P＜0.01).结论在适宜条件下,兔BMSCs可在体外分化成神经干细胞及神经元样细胞,并合成和分泌NE.     

牙周膜干细胞诱导骨髓间充质干细胞的牙向分化

目的 探讨牙周膜干细胞(PDLSC)诱导骨髓间充质干细胞(BMMSC)牙向分化的机制,为联合应用PDLSC和BMMSC再生牙周复合体提供实验依据.方法应用Transwell(R)小室法间接联合培养小型猪PDLSC和BMMSC,根据二者混合比例随机分为3组.A组:P∶M=10∶1共培养组;B组:P∶M=1∶1共培养;C组:P:M=1:10共培养,单独PDLSC和BMMSC培养组分别为阳性和阴性对照组.培养14 d,应用免疫荧光染色和实时定量PCR(qRT-PCR)分别检测scleraxis、osteocalcin(OCN)、osterix(OSX)、细胞外基质磷酸糖蛋白(MEPE)蛋白和mRNA表达情况,以判定PDLSC诱导BMMSC成牙的最佳配比比例.结果 免疫荧光染色和qRT-PCR结果均显示scleraxis、OCN和OSX相对mRNA表达水平在A、B、C组间没有统计学差异(P>0.05),但相对MEPE mRNA表达水平在A组却明显高于B组和C组(P＜0.01).结论 联合培养可促进BMMSC获得不同程度的PDLSC特性,且少量的PDLSC同样可以促进BMMSC获得牙源性干细胞特性.     

骨髓间充质干细胞移植促进大鼠肾缺血再灌注损伤的恢复

目的 观察骨髓间充质干细胞(MSCs) 缺血再灌注肾损伤大鼠体内的分化情况及对肾修复的促进作用.方法 72只雌性6周龄sD大鼠随机分为正常组、假手术组、缺血再灌注(I/R)组、MSCs移植组4组,分别于再灌注后12 h、3、7、14、42 d随机选取I/R组和MSCs组大鼠各6只,收获肾脏标本和血标本.测定血标本尿素氮和肌酐值;肾脏切片行HE染色、免疫组化PCNA染色、TUNEL法检测原位凋亡、激光共聚焦显微镜观察MSCs分化情况.结果 再灌注后7 d内,与I/R组比较,MSCs组BUN值、Scr值明显降低(P<0.05),组织学评分明显减低,PCNA阳性细胞数明显增多(P<0.05).再灌注后12 h,MSCs组凋亡细胞数少于I/R组(P<0.05).再灌注后42 d,肾小管中有BrdU阳性细胞.结论 MSCs移植可减轻急性肾缺血再灌注损伤鼠肾小管上皮细胞的损伤,促进肾功能恢复.少部分MSCs在体内可分化形成肾小管上皮细胞.     

bFGF对人脐带间充质干细胞增殖及胶原产生的影响

 目的：观察碱性成纤维细胞生长因子（bFGF）对人脐带间充质干细胞（hUCMSCs）增殖及I、III型胶原产生的影响。方法：贴壁培养hUCMSCs, 流式细胞术分析其表面标记(CD45、CD34、CD105、CD29和HLA-DR),成脂及成骨诱导其分化,以鉴定其为间充质干细胞,确定bFGF促增殖最适浓度为20 μg/L。分为实验组和对照组,实验组添加 bFGF (20  μg/L) 于DMED/F12培养液中,对照组使用DMED/F12常规培养液。MTT法测定hUCMSCs 存活和增殖能力, 分析bFGF 对hUCMSCs 增殖的影响,RT-PCR测定其I、III型胶原 mRNA的变化;Western blotting测定其I、III型胶原蛋白的含量。结果：MTT生长曲线提示bFGF促进hUCMSCs的增殖。用含与不含bFGF培养基培养的hUCMSCs 均表达 CD29,不表达 CD34、CD45和 HLA-DR,油红O染色和茜素红染色阳性。RT-PCR结果显示了实验组 I、III型胶原mRNA表达较对照组减少(P<0.05)。Western blotting检测结果显示了实验组I、III型胶原蛋白的表达较对照组减少(P<0.05)。结论：bFGF可显著促进hUCMSCs增殖,且不改变细胞的表面标志物表达。bFGF对hUCMSCsⅠ、Ⅲ型胶原mRNA和蛋白的表达呈抑制效应,提示其在促进创面愈合的同时可能不会引起Ⅰ、Ⅲ型胶原蛋白沉积,从而减少瘢痕增生。     

3D co-culture of hematopoietic stem and progenitor cells and mesenchymal stem cells in collagen scaffolds as a model of the hematopoietic niche

Here, we propose a collagen-based three-dimensional (3D) environment for hematopoietic stem and progenitor cells (HPC) with mesenchymal stem cells (MSC) derived either from bone marrow (BM) or umbilical cord (UC), to recapitulate the main components of the BM niche. Mechanisms described for HPC homeostasis were systematically analyzed in comparison to the conventional liquid HPC culture. The 3D-cultivation allows dissecting two sub-populations of HPC: (I) HPC in suspension above the collagen gel and (II) migratory HPC in the collagen fibres of the collagen gel. The different sites represent distinct microenvironments with significant impact on HPC fate. HPC in niche I (suspension) are proliferative and a dynamic culture containing HPC (CD34⁺/CD38^-), maturing myeloid cells (CD38⁺, CD13⁺, CAE⁺) and natural killer (NK) cells (CD56⁺). In contrast, HPC in niche II showed clonal growth with significant high levels of the primitive CD34⁺/CD38^- phenotype with starting myeloid (CD13⁺, CAE⁺) differentiation, resembling the endosteal part of the BM niche. In contrast, UC-MSC are not adequate for HSC expansion as they significantly enhance HPC proliferation and lineage commitment. In conclusion, the 3D-culture system using collagen and BM-MSC enables HPC expansion and provides a potential platform to dissect regulatory mechanisms in hematopoiesis.