人脐带间充质干细胞表达胚胎干细胞相关转录因子

背景：Nanog、Oct4和Sox2通过调节胚胎干细胞的基因转录,对其多潜能性和自我更新的能力具有关键性的调控作用,脐带间充质干细胞中这些胚胎干细胞相关转录因子的表达情况如何还不太清楚。 目的：研究脐带间充质干细胞中Nanog、Oct4和Sox2等这些胚胎干细胞相关转录因子的表达情况。 方法：胶原酶和胰酶消化法培养脐带间充质干细胞;mTeSRTM1体系进行无滋养层培养人胚胎干细胞,定量PCR比较上述两种细胞中Nanog、Oct4和Sox2 mRNA表达量的差异;免疫荧光检测上述两种细胞中Nanog、Oct4和Sox2的表达情况。 结果与结论：间充质干细胞表达胚胎干细胞标记Nanog、Oct4和Sox2,但Oct4主要表达在胞浆,且以Oct4B为主。脐带间充质干细胞Nanog、Oct4A和Sox2的表达量明显低于胚胎干细胞,其mRNA表达量分别为胚胎干细胞的20%,0.3%,10%左右。通过了解两种细胞Nanog、Oct4和Sox2的表达差异,可为优化脐带间充质干细胞重编程提供依据,也为进一步研究胚胎干细胞相关转录因子在成体干细胞表达起何种作用提供参考。     

Avian-induced pluripotent stem cells derived using human reprogramming factors

Avian species are important model animals for developmental biology and disease research. However, unlike in mice, where clonal lines of pluripotent stem cells have enabled researchers to study mammalian gene function, clonal and highly proliferative pluripotent avian cell lines have been an elusive goal. Here we demonstrate the generation of avian induced pluripotent stem cells (iPSCs), the first nonmammalian iPSCs, which were clonally isolated and propagated, important attributes not attained in embryo-sourced avian cells. This was accomplished using human pluripotency genes rather than avian genes, indicating that the process in which mammalian and nonmammalian cells are reprogrammed is a conserved process. Quail iPSCs (qiPSCs) were capable of forming all 3 germ layers in vitro and were directly differentiated in culture into astrocytes, oligodendrocytes, and neurons. Ultimately, qiPSCs were capable of generating live chimeric birds and incorporated into tissues from all 3 germ layers, extraembryonic tissues, and potentially the germline. These chimera competent qiPSCs and in vitro differentiated cells offer insight into the conserved nature of reprogramming and genetic tools that were only previously available in mammals.     

胎儿真皮间充质干细胞中的全能性相关转录因子的表达

背景：人真皮纤维母细胞或间充质干细胞可形成诱导性多能干细胞,但不同研究者所用的转录因子组合却并不相同。 目的：分离人胎儿真皮间充质干细胞,检测其全能性相关转录因子的表达。 方法：水囊引产5月龄胎儿,按照既往分离培养间充质干细胞的方法,得到胎儿真皮间充质干细胞。 结果与结论：胎儿真皮间充质干细胞高表达Oct4和C-myc、中度表达Sox2,是形成诱导性多能干细胞较好的体细胞。     

Spherical bioactive glass particles and their interaction with human mesenchymal stem cells in vitro

Sub-micron particles of bioactive glass (SMBGs) with composition 85 mol% SiO(2) and 15 mol% CaO were synthesised and characterised. Bioactivity was demonstrated by the formation of calcium apatite following 5 days immersion in simulated body fluid (SBF). The effect of a 24 h exposure of SMBGs (100 μg/ml, 150 μg/ml, 200 μg/ml) to human mesenchymal stem cells (hMSCs) on cell viability, metabolic activity and proliferation were determined using the LIVE/DEAD, MTT, total DNA and LDH assays after 1, 4 and 7 days of culture. None of the SMBG concentrations caused significant cytotoxicity at 1 and 4 days, but the doses of 150 and 200 μg/ml significantly decreased hMSC metabolic activity after 7 days of culture. Cell proliferation decreased as SMBG concentration increased; however none of the SMBGs tested had a significant effect on DNA quantity compared to the control. Confocal microscopy confirmed cellular uptake and localisation of the SMBGs in the hMSC cytoskeleton. Transmission electron microscopy revealed that the SMBGs localised inside the cell cytoplasm and cell endosomes. These findings are important for assessing the toxicity of sub-micron particles that may either be used as injectables for bone regeneration or generated by wear or degradation of bioactive glass scaffolds.     

Myocardin重组蛋白表达及其在人骨髓间充质干细胞重编程为血管平滑肌细胞中的作用

目的:研究心肌素(myocardin)重组蛋白的表达及分离纯化方法,并探讨myocardin重组蛋白对人骨髓间充质干细胞(human bone marrow mesenchymal stem cells,h BMSCs)向血管平滑肌细胞转分化的作用。方法:构建myocardin原核表达载体,摸索最佳诱导myocardin重组蛋白表达的方法及优化分离纯化方式。使用纳米转导试剂包裹myocardin形成纳米-蛋白复合体,转染h BMSCs,观察蛋白转导效率;蛋白转导成功后,检测血管平滑肌的特异性标志物平滑肌肌球蛋白重链的表达情况,观察h BMSCs向平滑肌细胞转化情况。结果:与传统方法相比较,高浓度法诱导myocardin重组蛋白的表达量更高,新采用的洗脱方式能获取更多的myocardin重组蛋白;纳米-myocardin复合体可成功转染h BMSCs并诱导其向血管平滑肌样细胞转化。结论:Myocardin重组蛋白能被高效转导到细胞内,并促使h BMSCs重编程为血管平滑肌样细胞。     

Chemical interaction of polyphosphoric acid with titanium and its effect on human bone marrow derived mesenchymal stem cell behavior

The aim of this study was to evaluate the effect of treating titanium (Ti) with polyphosphoric acid on the attachment and proliferation of human bone marrow derived mesenchymal stem cells (hBMSCs). Cleaned Ti disks were immersed into three different concentrations of polyphosphoric acid solution (0.1, 1, and 10 wt %) and 10 wt % orthophosphoric acid solution for 24 h at 37 degrees C. Ti immersed in distilled water for 24 h at 37 degrees C served as control. The level of polyphosphoric acid that interacted with the Ti surface was determined by measuring the surface P/Ti ratio (atom%/atom%) using X-ray photoelectron spectroscopy. Degrees of cell attachment (1, 3, 5 h after cell seed) and proliferation (1, 3, 5, and 7 days after cell seed) on each treated Ti disk were evaluated by MTS assay. The mean surface P/Ti ratios increased in a polyphosphoric acid concentration dependent manner. A significantly higher cell attachment was found on Ti treated with polyphosphoric acid in contrast to untreated Ti (control) for all three culture periods. MTS assay also revealed that cell proliferation levels significantly increased following a polyphosphoric acid dose dependency. Ti surface treatment with orthophosphoric acid did not influence the cell attachment and proliferation. It was concluded that polyphosphoric acid treatment of Ti enhanced the attachment and proliferation of hBMSCs.     

成人骨髓间质干细胞定向诱导为脂肪细胞的研究

目的:体外定向诱导成人骨髓间质干细胞(MSC)分化为脂肪细胞。方法:采用Ficoll-Paque淋巴细胞分离液(1.077×10³g/L)离心分离成人MSC,体外扩增,流式细胞仪检测MSC表面抗原表达,地塞米松、IBMX、胰岛素、indomethacin定向诱导MSC分化为脂肪细胞。油红O检测中性脂肪,光镜下细胞计数。结果:成人骨髓间质干细胞在体外扩增5代可获得1×10⁸个细胞。流式细胞仪检测结果显示CD29、CD44、CD90、CD105、CD166表达阳性,CD14、CD34、CD45、CD11a为阴性。诱导48h后,细胞内有脂滴出现,随着时间延长,脂滴逐渐增加并融合为脂泡。细胞由梭形转变为圆形或多角性。细胞计数结果显示85%以上细胞转变为脂肪细胞。结论:成人骨髓间质干细胞在体外可以分化为脂肪细胞。     

人骨髓源和胎盘源间充质干细胞对T细胞增殖抑制作用的比较

目的:比较研究人骨髓源和胎盘源间充质干细胞介导的T细胞增殖抑制作用机制。方法:应用流式细胞术(FCM)分别检测B7H4和PDL1在人骨髓源间充质干细胞(HBMSCs)和胎盘源间充质干细胞(HPMSCs)上的表达;应用抗体阻断试验分析B7H4、PDL1分别在HBMSCs和HPMSCs对T细胞增殖及周期影响中的作用。结果:HBMSCs上高表达免疫负性调控分子B7H4,而HPMSCs上高表达免疫负性调控分子PDL1。分别应用B7H4mAb和PDL1mAb阻断,可使HBMSCs和HPMSCs对PHA激发的T细胞增殖抑制作用明显减弱;下调T细胞周期中G0/G1期细胞数量,上调S期细胞数量,明显减弱HBMSCs和HPMSCs对T细胞周期的影响。结论:HBMSCs和HPMSCs可通过表达不同的免疫负性调控分子介导T细胞的增殖抑制作用。     

人骨髓间充质干细胞的分离、培养与鉴定

目的:探讨密度梯度离心结合贴壁筛选法分离培养人骨髓间充质干细胞(MSCs)的条件,为组织工程选择合适的种子细胞奠定基础.方法:采用密度梯度离心法将人MSCs自少量骨髓中分离并培养,观察其增殖和生长特性,绘制生长曲线,测定贴壁率,免疫组化与流式细胞仪细胞表型鉴定.结果:人MSCs生物性状稳定.不同代次生长曲线相似,第5～6d细胞数日最多;传代后10 h贴壁率高达90%.MSCs表达CD44、CD90,但不表达CD34、CD45.结论:密度梯度离心法是分离人MSCs的理想方法.MSCs能为组织工程提供足量种子细胞.     

Nanotopography as modulator of human mesenchymal stem cell function

Nanotopography changes human mesenchymal stem cells (hMSC) from their shape to their differentiation potential; however little is known about the underlying molecular mechanisms. Here we study the culture of hMSC on polydimethylsiloxane substrates with 350 nm grating topography and investigate the focal adhesion composition and dynamics using biochemical and imaging techniques. Our results show that zyxin protein plays a key role in the hMSC response to nanotopography. Zyxin expression is downregulated on 350 nm gratings, leading to smaller and more dynamic focal adhesion. Since the association of zyxin with focal adhesions is force-dependent, smaller zyxin-positive adhesion as well as its higher turnover rate suggests that the traction force in focal adhesion on 350 nm topography is decreased. These changes lead to faster and more directional migration on 350 nm gratings. These findings demonstrate that nanotopography decreases the mechanical forces acting on focal adhesions in hMSC and suggest that force-dependent changes in zyxin protein expression and kinetics underlie the focal adhesion remodeling in response to 350 nm grating topography, resulting in modulation of hMSC function.     

Nonstimulated human uncommitted mesenchymal stem cells express cell markers of mesenchymal and neural lineages

Ex vivo cultures of human bone marrow-derived mesenchymal stem cells (MSCs) contain subsets of progenitors exhibiting dissimilar properties. One of these subsets comprises uncommitted progenitors displaying distinctive features, such as morphology, a quiescent condition, growth factor production, and restricted tissue biodistribution after transplantation. In this study, we assessed the competence of these cells to express, in the absence of differentiation stimuli, markers of mesoderm and ectodermic (neural) cell lineages. Fluorescence microscopy analysis showed a unique pattern of expression of osteogenic, chondrogenic, muscle, and neural markers. The depicted "molecular signature" of these early uncommitted progenitors, in the absence of differentiation stimuli, is consistent with their multipotentiality and plasticity as suggested by several in vitro and in vivo studies.     

Immunobiology of human mesenchymal stem cells and future use in hematopoietic stem cell transplantation.

Mesenchymal stem cells (MSCs) may be derived from adult bone marrow, fat, and several fetal tissues. In vitro, MSCs can be expanded and have the capacity to differentiate into several mesenchymal tissues, such as bone, cartilage, and fat. They escape the immune system in vitro, and this may make them candidates for cellular therapy in an allogeneic setting. They also have immunomodulatory effects, inhibit T-cell proliferation in mixed lymphocyte cultures, prolong skin allograft survival, and may decrease graft-versus-host disease (GVHD) when cotransplanted with hematopoietic stem cells. MSCs induce their immunosuppressive effect via a soluble factor. Some candidates have been suggested, and various mechanisms have also been suggested, although contradictory data exist; this may be due to differences in the cells and systems tested. A major problem has been that it has been difficult to identify and isolate MSCs after transplantation in vivo. However, MSCs seem to enhance hematopoietic engraftment in recipients of autologous and allogeneic grafts. Recently, they were found to reverse grade IV acute GVHD of the gut and liver. No tolerance was induced, however. Controlled studies are warranted. Thus, in allogeneic stem cell transplantation, MSCs may be used for hematopoiesis enhancement, as GVHD prophylaxis, and for the treatment of severe acute GVHD. They are also of potential use in the treatment of organ transplant rejection and in autoimmune inflammatory bowel disorders where immunomodulation and tissue repair are needed.     

Substrates for human pluripotent stem cell cultures in conditioned medium of mesenchymal stem cells

We aimed to establish a culture system of human pluripotent stem cells (hPSCs), such as human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs), free from xenogeneic proteins, Matrigel(?) and conditioned medium of mouse embryonic fibroblasts. The conditioned culture medium consisted of mesenchymal stem cells derived from human bone marrow. We examined surface properties suitable for hPSC culture by using self-assembled monolayers (SAMs) of alkanethiols with four different functional groups: CH(3), OH, COOH and NH(2). hPSCs neither adhered nor proliferated on surfaces with a water contact angle higher than 40°. Based on this finding, the contact angle of a polystyrene (PSt) culture dish was reduced to less than 40°, and COOH and OH groups were introduced to its surface by oxygen plasma treatment, making the PSt dish suitable for hPSC culture. This combination of a PSt dish treated with oxygen plasma treatment and conditioned medium of mesenchymal stem cells achieved a long-term maintenance of hPSCs without differentiation.