TiO2 nanotubes as drug nanoreservoirs for the regulation of mobility and differentiation of mesenchymal stem cells

The extracellular microenvironment plays a key role in the regulation of cellular behavior. To mimic the natural extracellular microenvironment, TiO₂ nanotube (TNT) arrays as drug nanoreservoirs for loading of bone morphogenetic protein 2 (BMP2) were constructed on titanium substrates and then covered with multilayered coatings of gelatin/chitosan (Gel/Chi) for controlled drug release. The multilayered coatings were constructed via a spin-assisted layer-by-layer assembly technique. The successful fabrication of this system was monitored by field emission scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy and contact angle measurements. Multilayered coating with Gel/Chi retained the drug bioactivity and release properties, which were revealed by superoxide dismutase activity measurement. In addition, cytoskeleton observation and wound healing assay confirmed that BMP2-loaded and multilayer-coated TNT arrays were able to stimulate motogenic responses of mesenchymal stem cells (MSCs). More importantly, the system demonstrated that it was capable of promoting the osteoblastic differentiation of MSCs. This study may have potential impact on the development of bone implants for enhanced bone osseointegration.     

Improved mesenchymal stem cells attachment and in vitro cartilage tissue formation on chitosan-modified poly(L-lactide-co-epsilon-caprolactone) scaffold

Considering the load-bearing physiological requirement of articular cartilage, scaffold for cartilage tissue engineering should exhibit appropriate mechanical responses as natural cartilage undergoing temporary deformation on loading with little structural collapse, and recovering to the original geometry on unloading. A porous elastomeric poly l-lactide-co-?-caprolactone (PLCL) was generated and crosslinked at the surface to chitosan to improve its wettability. Human bone marrow derived mesenchymal stem cells (MSC) attachment, morphological change, proliferation and in vitro cartilage tissue formation on the chitosan-modified PLCL scaffold were compared with the unmodified PLCL scaffold. Chitosan surface promoted more consistent and even distribution of the seeded MSC within the scaffold. MSC rapidly adopted a distinct spread-up morphology on attachment on the chitosan-modified PLCL scaffold with the formation of F-actin stress fiber which proceeded to cell aggregation; an event much delayed in the unmodified PLCL. Enhanced cartilage formation on the chitosan-modified PLCL was shown by real-time PCR analysis, histological and immunochemistry staining and biochemical assays of the cartilage extracellular matrix components. The Young's modulus of the derived cartilage tissues on the chitosan-modified PLCL scaffold was significantly increased and doubled that of the unmodified PLCL. Our results show that chitosan modification of the PLCL scaffold improved the cell compatibility of the PLCL scaffold without significant alteration of the physical elastomeric properties of PLCL and resulted in the formation of cartilage tissue of better quality.     

Hydroxyapatite growth on anodic TiO2 nanotubes

In the present work, we study the growth of hydroxyapatite formation on different TiO(2) nanotube layers. The nanotube layers were fabricated by electrochemical anodization of titanium in fluoride-containing electrolytes. To study various nanotube lengths, layers with an individual tube diameter of 100 nm were grown to a thickness of approximately 2 mum or 500 nm. The ability to form apatite on the nanotube layers was examined by immersion tests combined with SEM, XRD and FT-IR investigations. For reference, experiments were also carried out on compact anodic TiO(2) layers. The results clearly show that the presence of the nanotubes on a titanium surface enhances the apatite formation and that the 2-mum thick nanotube layer triggers deposition faster than the thinner layers. Tubes annealed to anatase, or a mixture of anatase and rutile are clearly more efficient in promoting apatite formation than the tubes in their "as-formed" amorphous state.     

骨髓间充质干细胞研究进展

骨髓间充质干细胞是干细胞领域的研究热点之一。虽然近几年来有关间充质干细胞的研究已取得了很大进展,但仍有很多问题有待进一步解决。主要对间充质干细胞的异质性、分化与融合的问题、修复组织的机制、免疫性及研究方法等问题进行了综述。     

Aging of mesenchymal stem cells

The role of adult mesenchymal stem cells (MSC) in tissue maintenance and regeneration has received significant attention of late. Questions arise to what extent these cells are either subject to, or causes of aging; whether age-related changes in these cells are due to intrinsic factors or induced by the somatic environment. This review collates and examines recent data in support of these different theories. By means of introduction, a brief overview is given of current MSC definitions and their basic role in tissue regeneration followed by a comparative analysis of gerontological studies involving MSC. Evidence for extrinsic aging and various aging markers relating to morphology, proliferation, signalling, senescence markers, telomeres and telomerase, and other indicators is discussed. We observe that while the literature might often appear to conflict, many apparent discrepancies are attributable to inconsistent methods of extracting and isolating MSC which in fact contains various subsets of adult stem cells, varying not only in their differentiation potential but also in their vulnerability to senescence--ranging from quasi-somatic lifespan to perennial vigour. Thus, mesenchymal stem cells emerge as both subject to and key mediators of organismal aging.     

骨髓间充质干细胞研究进展

骨髓间充质干细胞是干细胞领域的研究热点之一.虽然近几年来有关间充质干细胞的研究已取得了很大进展,但仍有很多问题有待进一步解决.主要对间充质干细胞的异质性、分化与融合的问题、修复组织的机制、免疫性及研究方法等问题进行了综述.     

过表达IDO 大鼠骨髓间充质干细胞改善异位移植心脏存活

目的:探讨过表达IDO 大鼠骨髓间充质干细胞(BMSC)改善大鼠腹腔异位移植心脏的存活机制。方法:通过慢病毒载体GV308 携带IDO 基因转染大鼠骨髓间充质干细胞构建过表达IDO 大鼠骨髓间充质干细胞。建立大鼠腹腔异位移植心脏模型,经尾静脉给予相应细胞处理:1.利用超声心动图检测移植心脏心功能变化。于采用小动物活体成像系统评估移植心脏局部荧光强度。2.再取各组受体大鼠的脾脏,采用流式细胞技术检测CD40、CD86、CD80、MHCⅠ、CD274、CD45RA、CD45RA+CD45RB、Treg 细胞的表达情况。3.取各组移植心脏,采用HE 染色评估炎性细胞浸润情况。虞利用液相芯片检测各组血清IL-1α、IL-4、IL-1β、IL-2、IL-10、IFN-γ、IL-18、TGFβ1、TGFβ2、TGFβ3 因子的变化情况。结果:淤给予相应细胞处理,可见过表达IDO-BMSCs 处理后2 d 移植心脏的EF、FS 较其余各组有提高。于采用小动物活体评估可见过表达IDO-BMSCs 组移植心脏局部荧光强度最强。盂给予干预措施后2 d 可见过表达IDO-BMSCs 组脾脏细胞CD40、CD86、CD80、MHCⅠ、CD45RA、CD45RA+CD45RB 表达降低,而CD274、Treg 细胞的表达增高。榆采用液相芯片检测各组提取血清可见在2 d 时,过表达IDO-BMSCs 组血清中IL-1α、IL-4、IL-1β、IL-2、IFN-γ、IL-18 是降低的;IL-10、TGFβ1、TGFβ2、TGFβ3 表达量是升高的。HE 染色证实过表达IDO-BMSCs 组炎性细胞浸润少于其他组。结论:过表达IDO 的BMSCs 可以通过有效调节免疫DC、T 细胞及细胞因子,从多个免疫层面改善移植心脏存活。     

The effect of E-beam engineered surface structures on attachment, proliferation and differentiation of human mesenchymal stem cells

Electron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic implants. The effect of two newly designed highly porous E-beam engineered surface structures (cubic and star) on attachment, proliferation and differentiation of human mesenchymal stem cells (hMSCs) was investigated and compared to a solid sandblasted control. SEM analysis showed that the E-beam structures allowed cells to attach and spread. Proliferation on the new surface structures was comparable to the solid control. Furthermore, differentiation on the 3D structures was comparable to the control specimen. When culturing 300,000 cells for 10 days, the cubic structure showed a significantly higher differentiation rate compared to the sandblasted specimen. We conclude that the results for attachment, proliferation and differentiation of mesenchymal stem cells on the newly engineered 3-dimensional E-beam surface topographies are promising. In vivo experiments are necessary to assess the bone ingrowth potential of the new surface structures.     

间充质干细胞的免疫调节作用

间充质干细胞(MSC)已成功从动物体尤其骨髓中分离获得.干细胞,具有向多种组织和细胞如骨、脂肪、成软骨细胞等分化的潜能,这种潜能越来越引起人们关注,它可向受损的组织定向迁移以修复受损组织.体外资料研究表明,不管协同刺激信号存在与否,都具有低免疫原性.在体外MSC还具有免疫抑制活性,可抑制同种异体抗原或丝裂霉素刺激的T细胞扩增,阻止细胞毒性T细胞增殖,同时还具有调节炎性细胞的免疫活性使其向抗炎细胞分化的作用.因此,系统了解.MSC的生物学、免疫学特性将为人们深入阐明其免疫调节机制,并将其用于治疗自身免疫性病、组织修复及移植提供依据.     

High-potential human mesenchymal stem cells

Bone marrow-derived stromal mesenchymal stem cells (MSCs) have been characterized in vitro by their growth characteristics, the expression of a panel of surface antigens, and their potential to differentiate into mesenchymal lineages. They can be separated by physical methods as well as by immunological or chemical separation or cultivation. Different protocols are used in different laboratories, making the comparison of various reported MSC populations difficult. Here we describe a population of bone marrow-derived adult stem cells that has been separated on a Percoll gradient with low density. It is characterized by an extraordinary high proliferative potential and a conserved phenotype characteristic of MSCs that retain their plutipotentiality in culture, as evidenced by their ability to differentiate into osteo-, chondro-, and adipogenic lineages. Separation of these cells provide an effective and convenient method for rapid expansion of pluripotential human MSCs for clinical use where large amounts of stem cells are needed.     

改良原代培养体系提高人脐带间充质干细胞的产量

背景：目前关于脐带间充质干细胞培养方法的研究很多,但尚无关于初次培养后废弃物的相关研究。 目的：探讨优化人脐带来源间充质干细胞体外培养的最佳方法。方法：采用组织块贴壁法分离培养人脐带间充质干细胞,记为初次培养组。将原代培养瓶中的培养液及组织离心,重新分成组织组、混合组和纯液组进行再次培养。观察4组原代细胞的细胞形态、获得时间和细胞得率;MTT法绘制细胞生长曲线,流式细胞仪检测细胞周期及免疫表型。结果与结论：初次培养组、再次培养组织组、再次培养混合组、再次培养纯液组获取细胞的平均时间分别为(15.00±0.45) d,(7.0±0.3) d,(8.00±0.25) d,(8.00±0.25) d。每个T75培养瓶可获取的第1代细胞数分别为(4.0±0.5)×10⁵、(9.0±0.55)×10⁵、(15.0±0.2)×10⁵、(7.0±0.33)×10⁵个。倒置显微镜下观察4组细胞为形态相对均一的梭形贴壁细胞,呈平行排列生长或漩涡状生长。4组细胞的生长曲线、增殖活性、表面标记物检测均无明显差异。结果表明对脐带间充质干细胞的原代培养体系进行再次培养,可在短时间内扩增出大量原代细胞。1库：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;组织工程全文链接：     

低氧培养对间充质干细胞生物学的影响

背景：氧参与细胞内ATP的合成以供细胞代谢,氧浓度也是调节细胞生理功能的重要因素。骨髓间充质干细胞的生理病理活动是在低氧状态下进行,其发生机制还不完全清楚。 目的：回顾分析低氧培养对间充质干细胞生物学的影响的研究进展。 方法：应用计算机检索1997-01/2011-10 PubMed 数据库相关文章,检索词为“mesenchymal stem cells,hypoxia,HIF”;同时检索同期万方数据库、维普资讯网数据库和中国知网数据库相关文章,检索词“间充质干细胞,低氧培养,缺氧诱导因子”,共检索到文献1 120篇,最终纳入符合标准的文献48篇进行分析。 结果与结论：低氧预处理的骨髓间充质干细胞凋亡率将降低,其作用机制是通过上调血管内皮生长因子表达、抑制p53凋亡信号的表达以及促进抗凋亡蛋白Bcl-2的高表达来降低细胞凋亡。低氧下骨髓间充质干细胞通过抑制WNT信号通路和骨形态发生蛋白信号通路等通路,增加损伤组织的增殖能力;缺氧组织可诱导间充质干细胞迁移至缺氧区域,参与此过程的主要信号通路包括：血管内皮生长因子信号通路、基质细胞衍生因子1信号通路以及c-Met信号通路;低氧可提高间充质干细胞的黏附性,主要通过诱导细胞骨架蛋白以及细胞间黏附分子的高表达而实现;缺氧下间充质细胞增加Angiopoietin-1和血管内皮生长因子等因子的表达来促进细胞分化。     

Immunoregulatory function of mesenchymal stem cells

Mesenchymal stem cells (MSC) are a rare subset of stem cells residing in the bone marrow where they closely interact with hematopoietic stem cells and support their growth and differentiation. MSC can differentiate into multiple mesenchymal and non-mesenchymal lineages, providing a promising tool for tissue repair. In addition, MSC suppress many T cell, B cell and NK cell functions and may affect also dendritic cell activities. Due to their limited immunogenicity, MSC are poorly recognized by HLA-incompatible hosts. Based on these unique properties, MSC are currently under investigation for their possible use to treat immuno-mediated diseases. However, both their condition of immunoprivilege and their immunosuppressive function have recently been challenged when analyzed under particular experimental conditions. Thus, it is likely that MSC effects on the immune system may be deeply influenced not only by cell-to-cell interactions, but also by environmental factors shaping their phenotype and functions.     

胎盘间充质干细胞的应用研究

背景：胎盘间充质干细胞因其具有来源广泛、免疫原性低、不涉及伦理问题等优点成为种子细胞的新来源。 目的：阐述胎盘间充质干细胞的来源、生物学特性及应用最新研究进展。 方法：检索 PubMed、ScienceDirect、OvidSP、CNKI 数据库相关文章,检索时限为2003至 2015年,英文检索词为“Placenta,Mesenchymal stem cells,The placenta mesenchymal stem cells, Cell transplantation , Application mechanism”,中文检索词为“胎盘,间充质干细胞,胎盘间充质干细胞,细胞移植,应用机制”,从中筛选出与主题相关且论据可靠的部分文献,最终纳入57篇文章进行归纳综述。 结果与结论：目前已成功分离培养出胎盘间充质干细胞,并对其生物学特性进行研究,证明其具有干细胞源性及多向分化潜能。目前有较多关于胎盘间充质干细胞应用于实验动物及临床的研究,在骨组织工程、血管再生及神经组织等修复过程中均显示出了巨大的潜力,但胎盘间充质干细胞的具体应用机制目前尚不清楚,尚处于探索阶段,在胎盘间充质干细胞广泛应用于临床之前,仍有许多问题有待进一步研究明确,以确保其安全性和有效性。  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     

The concept of mesenchymal stem cells

In this chapter we examine whether criteria usually defining adult tissue stem cells apply to mesenchymal stem cells (MSCs) that give rise to cells of the skeletal connective tissues. MSCs appear to constitute a heterogeneous population of undifferentiated and committed, lineage-primed cells, capable of: homing upon engraftment to a number of growth microenvironments, extensive proliferation, producing large numbers of differentiated progeny, and functional tissue repair after injury. In addition, MSCs are extensively distributed throughout tissues, and bone marrow MSCs provide the stromal component of the niche of hematopoietic stem cells. The capacity of apparently differentiated mesenchymal cells to shift their differentiation pathway with changing microenvironmental conditions (known as differentiation plasticity) may be due to de-differentiation and reprogramming in MSCs. Because they present several features setting them apart from other stem cells, MSCs may constitute another paradigm for stem cell systems, where self-renewal and hierarchy are no longer essential, but where plasticity is the major characteristic.     

Immunosuppressive properties of mesenchymal stem cells

Mesenchymal stem cells (MSC) can be isolated from different adult tissues including bone marrow, adipose tissue, cord blood and placenta. MSCs modulate the immune function of the major immune cell populations involved in alloantigen recognition and elimination, including antigen presenting cells, T cells, B cells and natural killer cells. Many clinical trials are currently underway that employ MSCs to treat human immunological diseases. However, the molecular mechanism that mediates the immunosuppressive effect of MSCs is still unclear and the safety of using MSC in patient needs further confirmation. Here, we review the cytokines that activate MSCs and the soluble factors produced by MSCs, which allow them to exert their immunosuppressive effects. We review the mechanism responsible, at least in part, for the immune suppressive effects of MSCs and highlight areas of research required for a better understanding of MSC immune modulation.     

Proteomics of primary mesenchymal stem cells

Tissue and functional regeneration takes place in the body at various stages throughout life. However, bone, cartilage, tendons, blood vessels and cardiac muscle have a limited capacity for self repair and, after injury or disease, the regenerative ability of these adult tissues is often insufficient and leads to nonfunctional scar tissue. In this context, mesenchymal stem cells, which are adult multipotential progenitors of mesoderm cells (osteoblasts, chondrocytes, adipocytes and stroma cells), represent a major hope for tissue-engineered replacement and regenerative medicine. Furthermore, the autologous use of these cells prevents immunological responses against new tissues and the risks of disease transmission from donors, which are both common problems of organ transplantation. While the existence of mesenchymal stem cells is undisputed, many questions remain regarding their self-renewal and capacity to differentiate, their homogenous nature as a cell population throughout the body and their true potential in regenerative medicine. In this article, the proteomics studies carried out to characterize mesenchymal stem cells and to help understand their physiology are reviewed.     

骨髓基质干细胞的研究进展

骨髓基质干细胞具有取材简单、增殖速度快、抗原性小、培养过程中始终保持多向分化的潜能等特点,已经成为干细胞研究领域的热点,是最好的组织工程种子细胞之一。骨髓基质干细胞研究为组织器官的修复和替代提供了一个新的选择,具有广阔的临床应用前景。