Comparison of several attachment methods for human iPS,embryonic and adipose‐derived stem cells for tissue engineering

As actual stem cell application quickly approaches tissue engineering and regenerative medicine, aspects such as cell attachment to scaffolds and biomaterials become important and are often overlooked. Here, we compare the effects of several attachment proteins on the adhesion, proliferation and stem cell identity of three promising human stem cell types: human adipose‐derived stem cells (hASCs), human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Traditional tissue culture polystyrene plates (TCPS), Matrigel (Mat), laminin (Lam), fibronectin (FN) and poly‐ l ‐lysine (PLL) were investigated as attachment protein surfaces. For hASCs typically cultured on TCPS, laminin resulted in the greatest cell attachment and proliferation with largest cell areas, indicating favourability by cell spreading. However, mesenchymal stem cell markers indicative of hASCs were slightly more expressed on surfaces with lowest cell attachment, corresponding to increased cell roundness, a newly observed attribute in hASCs possibly indicating a more stem cell‐like character. hESCs preferred Matrigel as a feeder‐free culture surface. Interestingly, hiPSCs favoured laminin over Matrigel for colony expansion, shown by larger cell colony area and perimeter lengths, although cell numbers and stem cell marker expression level remained highest on Matrigel. These data provide a practical reference guide for selecting a suitable attachment method for using human induced pluripotent, embryonic or adipose stem cells in tissue engineering and regenerative medicine applications. Copyright © 2012 John Wiley & Sons, Ltd.     

胚胎干细胞培养及建系方法探讨

目的探索人胚胎干细胞建系方法,为干细胞和再生医学领域的科学研究提供可靠的实验方法和技术。方法分别利用有饲养层和无饲养层培养体系培养人的胚胎干细胞,用免疫荧光法、逆转录聚合酶链式扩增(RTPCR)法和体内形成畸胎瘤的方法鉴定其干细胞特征。结果培养的人胚胎干细胞,传代至33代时表达干细胞表面标志物Oct-4,SSEA-3,Tra-1-60,Tra-1-81和全能型因子C-MYC KLF-4 OCT-4 SOX-2,畸胎瘤组织切片中分别有消化腺内皮(内胚层)、脂肪组织(中胚层)和神经组织(外胚层)等组织形成,说明该胚胎干细胞形成的畸胎瘤有向三胚层分化的潜能。结论成功建立了人胚胎干细胞建系,所建立的培养人胚胎干细胞的方法可行。     

高效制备昆明鼠胚胎成纤维细胞饲养层

背景:小鼠胚胎成纤维细胞作为饲养层是胚胎干细胞培养最常用的方法,能有效抑制胚胎干细胞分化并促进其增殖,但其制备过程繁琐,工作量大,准备周期长。目的:探索建立小鼠胚胎成纤维细胞饲养层简单、高效的培养体系。方法:取13.5d胎龄胎鼠用改良组织块法及简化酶消化法分离培养原代成纤维细胞,倒置显微镜下观察不同方法培养的原代和传代鼠胚胎成纤维细胞的生长形态、结构及细胞数量变化。收集鼠胚胎成纤维细胞进行冻存,复苏后细胞经不同浓度作用时间的丝裂霉素C处理,制备饲养层。结果与结论:两种简化方法培养的原代鼠胚胎成纤维细胞生长状态良好,得到高效优质足量细胞,操作过程简单,省去了多次消化、离心、细胞计数等繁琐操作,均适宜于鼠胚胎成纤维细胞的原代培养。简化复苏法复苏后的细胞,按其生长汇合情况,以丝裂霉素C10mg/L作用1.5～2.0h或1mg/L培养过夜,省时并可获得细胞生长状态最佳的饲养层。     

Urothelial cell expansion and differentiation are improved by exposure to hypoxia

Cells obtained from a patient's biopsy have to be expanded after extraction to produce autologous tissues, but standard cell culture conditions often limit their growth or lifespan and could induce early and inadequate cell differentiation. Moreover, it has previously been reported that the air–liquid interface, that induces maturation of the urothelium, stimulated inadequate differentiation associated with aberrant keratin‐14 expression. The aim of this study was to test the benefits of hypoxia during expansion of urothelial cells and maturation of the bladder epithelium in the context of tissue engineering. Bladder mucosa substitutes were reconstructed using the self‐assembly method with urothelial cells (UCs) expanded in normoxia or hypoxia. Hypoxia improved UCs expansion until passage P7, whereas normoxic conditions limited the use of UCs to passage P4. Maturation of the urothelium was also compared in normoxic vs. hypoxic conditions. Using laminin V, p63, Ki‐67, keratin‐5 and ‐14, Claudin‐4 and zonula occludens protein‐1, we show a better organization of the basal UC layer in hypoxia despite a thinner intermediate layer. Finally, barrier function was assessed by permeation tests. Cell culture in hypoxia allowed the generation of bioengineered urological tissue closer to native bladder characteristics, which represents a promising avenue to circumvent the lack of adequate tissues for reconstructive surgery. Copyright © 2017 John Wiley & Sons, Ltd.     

C57BL／6小鼠胚胎成纤维细胞生物学特性及饲养层制备

背景：昆明小鼠胚胎成纤维细胞是目前最常用的饲养层细胞,C57BL/6小鼠胚胎成纤维细胞作为饲养层的研究鲜有报道。目的：体外分离和培养C57BL/6小鼠胚胎成纤维细胞,制备饲养层,力求扩大小鼠胚胎成纤维细胞的来源。方法：用不同浓度胰蛋白酶分步消化法体外分离和培养C57BL/6小鼠胚胎成纤维细胞,观察其生物学特性,研究其生长规律,并制备小鼠胚胎成纤维细胞饲养层,检测干细胞在所制备饲养层上的生长状态。结果与结论：不同浓度胰蛋白酶分步消化法制备的C57BL/6小鼠胚胎成纤维细胞生长状态好,获得的成纤维细胞数量多,增殖活跃。在细胞冻存后1,2周、1,3,6个月内复苏的细胞存活率差异无显著性意义。C57BL/6小鼠胚胎成纤维细胞在第2-5代增殖旺盛,第6代以后细胞增殖出现明显下降。种植到培养皿上的C57BL/6小鼠饲养层细胞在种植后3 d内活力高,种植4 d以后细胞活力急剧下降。所以C57BL/6小鼠胚胎成纤维细胞来源的饲养层的最佳使用时间为灭活后3 d内,C57BL/6小鼠胚胎成纤维细胞饲养层和昆明小鼠胚胎成纤维细胞饲养层一样,能很好地支持胚胎干细胞及诱导多能干细胞生长。     

Agonism of Wnt–β‐catenin signalling promotes mesenchymal stem cell (MSC) expansion

Promoting mesenchymal stem cell (MSC) proliferation has numerous applications in stem cell therapies, particularly in the area of regenerative medicine. In order for cell‐based regenerative approaches to be realized, MSC proliferation must be achieved in a controlled manner without compromising stem cell differentiation capacities. Here we demonstrate that 6‐bromoindirubin‐3′‐oxime (BIO) increases MSC β‐catenin activity 106‐fold and stem cell‐associated gene expression ~33‐fold, respectively, over untreated controls. Subsequently, BIO treatment increases MSC populations 1.8‐fold in typical 2D culture conditions, as well as 1.3‐fold when encapsulated within hydrogels compared to untreated cells. Furthermore, we demonstrate that BIO treatment does not reduce MSC multipotency where MSCs maintain their ability to differentiate into osteoblasts, chondrocytes and adipocytes using standard conditions. Taken together, our results demonstrate BIO's potential utility as a proliferative agent for cell transplantation and tissue regeneration. Copyright © 2013 John Wiley & Sons, Ltd.     

Rotary orbital suspension culture of embryonic stem cell‐derived neural stem/progenitor cells: impact of hydrodynamic culture on aggregate yield,morphology and cell phenotype

Embryonic stem (ES)‐derived neural stem/progenitor cells (ES‐NSPCs) constitute a promising cell source for application in cell therapies for the treatment of central nervous system disorders. In this study, a rotary orbital hydrodynamic culture system was applied to single‐cell suspensions of ES‐NSPCs, to obtain homogeneously‐sized ES‐NSPC cellular aggregates (neurospheres). Hydrodynamic culture allowed the formation of ES‐NSPC neurospheres with a narrower size distribution than statically cultured neurospheres, increasing orbital speeds leading to smaller‐sized neurospheres and higher neurosphere yield. Neurospheres formed under hydrodynamic conditions (72 h at 55 rpm) showed higher cell compaction and comparable percentages of viable, dead, apoptotic and proliferative cells. Further characterization of cellular aggregates provided new insights into the effect of hydrodynamic shear on ES‐NSPC behaviour. Rotary neurospheres exhibited reduced protein levels of N‐cadherin and β‐catenin, and higher deposition of laminin (without impacting fibronectin deposition), matrix metalloproteinase‐2 (MMP‐2) activity and percentage of neuronal cells. In line with the increased MMP‐2 activity levels found, hydrodynamically‐cultured neurospheres showed higher outward migration on laminin. Moreover, when cultured in a 3D fibrin hydrogel, rotary neurospheres generated an increased percentage of neuronal cells. In conclusion, the application of a constant orbital speed to single‐cell suspensions of ES‐NSPCs, besides allowing the formation of homogeneously‐sized neurospheres, promoted ES‐NSPC differentiation and outward migration, possibly by influencing the expression of cell–cell adhesion molecules and the secretion of proteases/extracellular matrix proteins. These findings are important when establishing the culture conditions needed to obtain uniformly‐sized ES‐NSPC aggregates, either for use in regenerative therapies or in in vitro platforms for biomaterial development or pharmacological screening. Copyright © 2016 John Wiley & Sons, Ltd.     

兔骨髓间充质干细胞向尿路上皮分化后构建膀胱组织工程化移植物

背景：尿路上皮细胞是泌尿系组织工程领域重要的种子细胞,但是难以体外大量扩增;有研究表明骨髓间充质干细胞可以向尿路上皮细胞分化,但关于分化后细胞在植入动物体内后上皮生成情况,以及分化后细胞在组织工程领域的具体应用研究尚不多。目的：分离、扩增兔骨髓间充质干细胞,诱导骨髓间充质干细胞向尿路上皮细胞分化并与兔膀胱脱细胞基质构建组织工程化移植物,了解分化后细胞作为种子细胞的效果。方法：12只8周龄雄性新西兰大白兔胫骨穿刺,抽取骨髓,密度梯度离心法分离骨髓间充质干细胞,第4或5代细胞以条件培养基培养2周,进行分化后细胞的鉴定。随后将分化后细胞种植在膀胱脱细胞基质上构建组织工程化移植物,进行膀胱修补;另12只动物作为对照组以尿路上皮细胞与膀胱脱细胞基质构建复合物行膀胱修补。结果与结论：骨髓间充质干细胞培养成功并在体外扩增,由条件培养基培养诱导分化后,PCR检测提示分化后细胞干细胞标志物CD44表达降低,而上皮细胞标志物UP1a表达升高,行免疫荧光检测发现分化后细胞能表达尿路上皮特异性标志物UP1a,而骨髓间充质干细胞无表达。分化后细胞构建的组织工程化移植物在膀胱修补2周后可形成稳定连续的上皮覆盖,上皮层厚度与尿路上皮细胞构建的组织工程化移植物类似。提示骨髓间充质干细胞向尿路上皮诱导分化后可作为泌尿系组织工程的种子细胞,可能是尿路上皮细胞之外的又一新选择。     

SIRT1‐dependent anti‐senescence effects of cell‐deposited matrix on human umbilical cord mesenchymal stem cells

Human umbilical cord‐derived mesenchymal stem cells (UC‐MSCs) are considered an attractive cell source for tissue regeneration. However, environmental oxidative stress can trigger premature senescence in MSCs and thus compromises their regenerative potential. Extracellular matrix (ECM) derived from MSCs has been shown to facilitate cell proliferation and multi‐lineage differentiation. This investigation evaluated the effect of cell‐deposited decellularized ECM (DECM) on oxidative stress‐induced premature senescence in UC‐MSCs. Sublethal dosages of H₂O₂, ranging from 50 μm to 200 μm , were used to induce senescence in MSCs. We found that DECM protected UC‐MSCs from oxidative stress‐induced premature senescence. When treated with H₂O₂ at the same concentration, cell proliferation of DECM‐cultured UC‐MSCs was twofold higher than those on standard tissue culture polystyrene (TCPS). After exposure to 100 μm H₂O₂, fewer senescence‐associated β‐galactosidase‐positive cells were observed on DECM than those on TCPS (17.6  ±  4.0% vs. 60.4  ±  6.2%). UC‐MSCs cultured on DECM also showed significantly lower levels of senescence‐related regulators, such as p16^INK4α and p21. Most importantly, DECM preserved the osteogenic differentiation potential of UC‐MSCs with premature senescence. The underlying molecular mechanisms involved the silent information regulator type 1 (SIRT1)‐dependent signalling pathway, confirmed by the fact that the SIRT1 inhibitor nicotinamide counteracted the DECM‐mediated anti‐senescent effect. Collagen type I, rather than fibronectin, partially contributed to the protective effect of decellularized matrix. These findings provide a new strategy of using stem cell‐deposited matrix to overcome the challenge of cellular senescence and to facilitate the clinical application of MSCs in regenerative medicine. Copyright © 2017 John Wiley & Sons, Ltd.     

An in vitro expansion score for tissue‐engineering applications with human bone marrow‐derived mesenchymal stem cells

Human bone marrow‐derived mesenchymal stem cells (MSCs) have limited growth potential in vitro and cease to divide due to replicative senescence, which from a tissue‐engineering perspective has practical implications, such as defining the correct starting points for differentiation and transplantation. Time spent in culture before the loss of required differentiation potential is different and reflects patient variability, which is a problem for cell expansion. This study aimed to develop a score set which can be used to quantify the senescent state of MSCs and predict whether cells preserve their ability to differentiate to osteogenic, adipogenic and chondrogenic phenotypes, based on colony‐forming unit (CFU) assay, population doubling time (PDT), senescence‐associated β‐galactosidase (SA‐β‐Gal) activity, cell size, telomere length and gene expression of MSCs cultured in vitro over 11 passages. This set of morphological, physiological and genetic senescence markers was correlated to the ability of MSCs to differentiate. Differentiation efficiency was assessed by marker genes and protein expression. CFUs decreased with increasing passage number, whereas SA‐β‐Gal activity and PDT increased; however, the correlation with MSCs' differentiation potential was sometimes unexpected. The expression of genes related to senescence was higher in late‐passage cells than in early‐passage cells. Early‐passage cells underwent efficient osteogenic differentiation, with mid‐passage cells performing best in chondrogenic differentiation. Late‐passage cells preserve only adipogenic differentiation potential. Based on this marker set, we propose a senescence score in which combined markers give a reliable quality control of MSCs, not depending only on mechanistic passage number. Copyright © 2013 John Wiley & Sons, Ltd.     

高效制备昆明鼠胚胎成纤维细胞饲养层

背景：小鼠胚胎成纤维细胞作为饲养层是胚胎干细胞培养最常用的方法,能有效抑制胚胎干细胞分化并促进其增殖,但其制备过程繁琐,工作量大,准备周期长。目的：探索建立小鼠胚胎成纤维细胞饲养层简单、高效的培养体系。方法：取13.5d胎龄胎鼠用改良组织块法及简化酶消化法分离培养原代成纤维细胞,倒置显微镜下观察不同方法培养的原代和传代鼠胚胎成纤维细胞的生长形态、结构及细胞数量变化。收集鼠胚胎成纤维细胞进行冻存,复苏后细胞经不同浓度作用时间的丝裂霉素C处理,制备饲养层。结果与结论：两种简化方法培养的原代鼠胚胎成纤维细胞生长状态良好,得到高效优质足量细胞,操作过程简单,省去了多次消化、离心、细胞计数等繁琐操作,均适宜于鼠胚胎成纤维细胞的原代培养。简化复苏法复苏后的细胞,按其生长汇合情况,以丝裂霉素C10mg/L作用1.5～2.0h或1mg/L培养过夜,省时并可获得细胞生长状态最佳的饲养层。     

Differentiation of human pluripotent stem cells to retinal pigmented epithelium in defined conditions using purified extracellular matrix proteins

A potential application of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) is the generation of retinal pigmented epithelium (RPE) to treat age‐related macular degeneration (AMD), a common but incurable retinal disease. RPE cells derived from hESCs (hESC‐RPEs) and iPSCs (iPSC‐RPEs) express essential RPE markers and can rescue visual function in animal models. However, standard differentiation protocols yield RPE cells at low frequency, especially from iPSC lines, and the common use of Matrigel and xenogeneic feeder cells is not compatible with clinical applications. The extracellular matrix (ECM) can affect differentiation, and therefore changes in ECM composition may improve the frequency of stem cell‐RPE differentiation. We selected several purified ECM proteins and substrates, based on the in vivo RPE ECM environment, and tested their ability to support iPSC‐RPE differentiation and maintenance. iPSCs differentiated on nearly all tested substrates developed pigmented regions, with Matrigel and mouse laminin‐111 supporting the highest pigmentation frequencies. Although iPSC‐RPEs cultured on the majority of the tested substrates expressed key RPE genes, only six substrates supported development of confluent monolayers with normal RPE morphology, including Matrigel and mouse laminin‐111. iPSCs differentiated on mouse laminin‐111 produced iPSC‐RPEs expressing RPE proteins, and hESCs differentiated on mouse laminin‐111 resulted in high yields of functional hESC‐RPEs. This identification of key ECM proteins may assist with future scaffold designs and provide peptide sequences for use in synthetic, xeno‐free, GMP‐compliant generation of RPE from human pluripotent stem cells relevant to clinical translation. Copyright © 2012 John Wiley & Sons, Ltd.     

Novel method for the isolation of adipose stem cells (ASCs)

Adipose stem cells (ASCs) represent a cell population with great potential for tissue engineering applications. Several articles have been published showing the proliferation and differentiation potential, the markers and the wide range of potential applications of these cells. In the majority of these studies the ASCs are isolated using a basic enzymatic procedure, which results in a quite heterogeneous cell population that compromises their proliferation and differentiation. This paper reports the development and optimization of a new isolation/purification method that allows populations of ASCs to be obtained, which significantly reduces (and eventually eliminates) the ‘contamination’ of other cell types. This method is based on the use of immunomagnetic beads coated with specific antibodies. The first part of the study described here analysed the expression of marker genes for stem cells and the colony‐forming unit (CFU) capacity of the cells isolated, while the second part is dedicated to the osteogenic differentiation potential of the isolated cells. The results showed that, using the isolation method based on immunomagnetic beads, it was possible to obtain ASCs and also underline the existence of several subpopulations of stem cells in the adipose tissue. Copyright © 2008 John Wiley & Sons, Ltd.     

In vitro evaluation of gel‐encapsulated adipose derived stem cells: Biochemical cues for in vivo peripheral nerve repair

Adipose‐derived stem cells (ASC) are becoming one of the most exploited cells in peripheral nerve repair. They are fast‐growing and able to protect neurons from apoptosis; they can reduce post‐injury latency and the risk of muscle atrophy. This study evaluates laminin‐loaded fibrin gel as an ASC‐carrying scaffold for nerve repair. In vitro, ASC retained their proliferative activity but showed significant increase in proliferation rate when encapsulated in gels with low laminin concentrations (i.e., 1 μg/mL). We observed a linear decrease of ASC proliferation rate with increasing laminin concentration from 1 to 100 μg/mL. We next examined the effect of the ASC‐carrying fibrin gels on in vitro dorsal root ganglia (DRG) neurite extension, then in vivo sciatic nerve regeneration in adult rats. The ASC‐carrying gel was embedded in 15‐mm‐long, 1.5‐mm‐diameter polydimethylsiloxane regenerative conduits for in vivo evaluation. At 8‐week post implantation, robust regeneration was observed across the long gap. Taken together, these results suggest ASC‐carrying gels are a potential path to improve the efficacy of nerve regeneration through artificial guidance conduits and electrode nerve interfaces.     

冷冻前后脐带间充质干细胞造血支持能力的比较

背景：低温冻存脐带间充质干细胞已成为研究热点,但关于冻存后其造血支持能力变化的报道甚少。目的：比较冷冻前后脐带间充质干细胞体外支持成人骨髓单个核细胞造血集落生成的能力。方法：分别将冷冻前后的人脐带间充质干细胞和人骨髓来源的间充质干细胞培养至第3代,经2.5g/L丝裂霉素C处理制备为细胞滋养层,与成人异体骨髓单个核细胞共培养。体外培养至35d应用甲基纤维素法检测造血干/祖细胞集落的增殖状态。结果与结论：冷冻人脐带间充质干细胞组集落形态、大小上与骨髓间充质干细胞组和未冷冻人脐带间充质干细胞组相似,3者均比空白组集落数量多,差异有显著性意义（P〈0.05）。与未冷冻人脐带间充质干细胞组相比,冷冻人脐带间充质干细胞组集落数更少,差异有显著性意义（P〈0.05）。实验结果说明冷冻前后人脐带间充质干细胞与骨髓间充质干细胞对骨髓单个核细胞均有造血刺激作用,但人脐带间充质干细胞冷冻后的造血支持作用有所减弱。     

Study on genetic stability in human urothelial cells in vitro

Quality control studies addressing gene expression changes and genetic stability are of vital importance in regenerative medicine. In order to rule out that in vitro expansion gives rise to gene expression changes that could favour oncogenic events, this study applied a total human gene expression chip (Affymetrix®) and bioinformatics analysis using the Ingenuity web‐based application in combination with an analysis of chromosomal copy number variations using array comparative genomic hybridization. Urothelial cells presented a general repression of genes required for cell cycle progression and upregulation of growth‐inhibitory genes, as well as a decrease in deoxyribose nucleic acid replication after long‐term culture. Molecules were identified with a potential to regulate human urothelial cell senescence, such as the micro‐ribonucleic acid Let‐7. Human urothelial cells did not acquire copy number variations after long‐term culture and the cells had a normal expression of oncogenes and tumor suppressor genes. Altogether, both gene expression studies and array comparative genomic hybridization indicated a good quality of in vitro propagated cells. For tissue engineering purposes, these analyses could be used for quality control assessments before transplantation back to the patient. Copyright © 2016 John Wiley & Sons, Ltd.     

Cell‐laden biphasic scaffolds with anisotropic structure for the regeneration of osteochondral tissue

Sufficient treatment of chondral and osteochondral defects to restore function of the respective tissue remains challenging in regenerative medicine. Biphasic scaffolds that mimic properties of bone and cartilage are appropriate to regenerate both tissues at the same time. The present study describes the development of biphasic, but monolithic scaffolds based on alginate, which are suitable for embedding of living cells in the chondral part. Scaffolds are fabricated under sterile and cell‐compatible conditions according to the principle of diffusion‐controlled, directed ionotropic gelation, which leads to the formation of channel‐like, parallel aligned pores, running through the whole length of the biphasic constructs. The synthesis process leads to an anisotropic structure, as it is found in many natural tissues. The two different layers of the scaffolds are characterized by different microstructure and mechanical properties which provide a suitable environment for cells to form the respective tissue. Human chondrocytes and human mesenchymal stem cells were embedded within the chondral layer of the biphasic scaffolds during hydrogel formation and their chondrogenic (re)differentiation was successfully induced. Whereas viability of non‐induced human mesenchymal stem cells decreased during culture, cell viability of human chondrocytes and chondrogenically induced human mesenchymal stem cells remained high within the scaffolds over the whole culture period of 3 weeks, demonstrating successful fabrication of cell‐laden centimetre‐scaled constructs for potential application in regenerative treatment of osteochondral defects. Copyright © 2014 John Wiley & Sons, Ltd.     

人胚胎干细胞无血清无饲养层培养体系的建立

背景:研究表明FGF2,TGFβ/activin/nodal和IGF信号通路是人胚胎干细胞保持其多能性所必需的,然而直接添加外源性碱性成纤维细胞生长因子、转化生长因子β和胰岛素是否能够维持人胚胎干细胞的自我更新目前尚无报道.目的:拟建立人胚胎干细胞无饲养层无血清条件下的培养体系.设计,时间及地点:细胞学体外观察,于2007-09/2009-02在中国科学院昆明动物研究所完成.材料:12.5～13.5d龄清洁级ICR孕鼠2只,由昆明医学院动物中心提供.人胚胎干细胞株BG02购自美国Bresagen公司.方法:①消化离心BG02细胞,重悬于无饲养层过渡培养基后接种,常规培养5～7 d,挑去分化的人胚胎干细胞,加入分散酶消化,切割成小团块,离心重悬后按1:3比例重新接种预铺层粘连蛋白的4孔板,此时培养基换成无血清无饲养层培养基,由80%DMEM/F12、20%KSR、2 mmol/L glutamine、1%非必需氨基酸、0.1 mmol/L β-巯基乙醇、ITS(×1)、10~6 U/L青霉素、100 mg/L 链霉素、4 μg/L碱性成纤维细胞生长因子、0.12 μg/L转化生长因子β1组成.②无菌条件下取出ICR胎鼠,组织块胰酶消化法分离培养小鼠胚胎成纤维细胞,接种在0.1%明胶包被的6孔板中即为饲养层.将生长在小鼠胚胎成纤维细胞饲养层上的人胚胎干细胞株BG02预铺至有层粘连蛋白的培养板上,加入含碱性成纤维细胞生长因子、转化生长因子β1及ITS的无血清培养基连续培养.主要观察指标:观察BG02细胞在无血清无饲养层培养体系中的形态,采用细胞免疫组化法检测人胚胎干细胞特异性分子标志的表达,检测BG02细胞体外分化能力及其核型,比较BG02细胞在无血清无饲养层和小鼠胚胎成纤维细胞饲养层培养体系中的生长情况、细胞集落分化率.结果:在无血清无饲养层培养体系中,BG02细胞连续传代20代,细胞呈典型的人胚胎干细胞形态特征;BG02细胞表达SSEA-4,SSEA-3,TRA-1-60,TRA-1-81,Oct-4,但不表达SSEA-1;培养20 d后,BG02细胞进一步分化成3个胚层的细胞,分化细胞能够表达甲胎蛋白、巢蛋白、α-肌动蛋白;培养至20代细胞核型均正常(46XY).与在饲养层培养体系下比较,无血清无饲养层条件下BG02细胞BG02细胞生长速度减慢,细胞倍增时间明显延长(P＜0.05),集落分化率明显升高(P＜0.05).结论:实验初步建立了入胚胎干细胞无血清无饲养层的培养体系,添加碱性成纤维细胞生长因子、转化生长因子β1和ITS可以维持人胚胎干细胞的自我更新.     

国内首对同一父母来源HLA相同的人胚胎干细胞系的建立

目的:建立国内首对同父母来源的人胚胎干细胞(human embryonic stem cell,hESC)系,为干细胞的定向诱导分化提供内参对照模型。方法:利用体外受精后第3天不适宜进行胚胎移植的低质量胚胎,采用机械切割法分离囊胚内细胞团(ICM),接种到丝裂霉素C处理的小鼠饲养层上,对建立的hESC进行多能性潜能检测。结果:成功建立一对具有多能特性的hESC系,体外长期培养维持正常核型,STR显示较高的亲缘性,HLA配型完全相同。结论:本研究建立了国内首对同一父母来源的HLA完全相同的hESC,其遗传背景一致,这为细胞的定向诱导分化体系筛选提供一个很好的内参对照,同时也为干细胞的移植排斥反应、培养扩增等研究提供很好的对比参照模型。     

Polymeric nanofibrous substrates stimulate pluripotent stem cells to form three‐dimensional multilayered patty‐like spheroids in feeder‐free culture and maintain their pluripotency

Expansion of pluripotent stem cells in defined media devoid of animal‐derived feeder cells to generate multilayered three‐dimensional (3D) bulk preparations or spheroids, rather than two‐dimensional (2D) monolayers, is advantageous for many regenerative, biological or disease‐modelling studies. Here we show that electrospun polymer matrices comprised of nanofibres that mimic the architecture of the natural fibrous extracellular matrix allow for feeder‐free expansion of pluripotent human induced pluripotent stem cells (IPSCs) and human embryonic stem cells (HESCs) into multilayered 3D 'patty‐like' spheroid structures in defined xeno‐free culture medium. The observation that IPSCs and HESCs readily revert to 2D growth in the absence of the synthetic nanofibre membranes suggests that this 3D expansion behaviour is mediated by the physical microenvironment and artificial niche provided by the nanofibres only. Importantly, we could show that such 3D growth as patties maintained the pluripotency of cells as long as they were kept on nanofibres. The generation of complex multilayered 3D structures consisting of only pluripotent cells on biodegradable nanofibre matrices of the desired shape and size will enable both industrial‐scale expansion and intricate organ–tissue engineering applications with human pluripotent stem cells, where simultaneous coupling of differentiation pathways of all germ layers from one stem cell source may be required for organ formation. Copyright © 2014 John Wiley & Sons, Ltd.