Establishment of retinal progenitor cell clones by transfection with Pax6 gene of mouse induced pluripotent stem (iPS) cells

We previously reported that transfection of Pax6 gene which regulated early events in eye development into mouse ES cells brought about their differentiation into retinal progenitors. Here, we attempted to establish cloned retinal progenitors which had ability to further differentiate into photoreceptor like cells by transfecting mouse induced pluripotent stem (iPS) cells with Pax6 gene. Undifferentiated iPS cells were transfected with Pax6 cDNA, followed by selection with G418. After limiting dilution culture, we selected cloned Pax6-transfected cells, which simultaneously expressed mRNAs of Nestin, Musashi1, Six3 and Chx10 for further characterization. We obtained totally 8 clonally expanding Pax6-transfected cells. They started to express mRNAs of Brn3b, Cone-rod homeobox (Crx), pkc, CD73, rhodopsin and the γ-subunit of rod cGMP phosphodiesterase (PDEγ). Flow cytometric analysis revealed that almost half of the cells were CD73+, a marker of photoreceptor precursors. Western blotting confirmed cytoplasmic protein expression of rhodopsin. High KCl stimulation increased free Ca influx into the cells on Ca²⁺ imaging. iPS cells transfected with Pax6 gene, followed by subsequent limiting dilution culture became retinal progenitors including photoreceptor like cells. The cloned cell lines may be useful for analyzing differentiation requirement of retinal progenitors.     

Distinct Stem Cells Subpopulations Isolated from Human Adipose Tissue Exhibit Different Chondrogenic and Osteogenic Differentiation Potential

Recently adipose tissue has become a research topic also for the searching for an alternative stem cells source to use in cell based therapies such as tissue engineer. In fact Adipose Stem Cells (ASCs) exhibit an important differentiation potential for several cell lineages such as chondrogenic, osteogenic, myogenic, adipogenic and endothelial cells. ASCs populations isolated using standard methodologies (i.e., based on their adherence ability) are very heterogeneous but very few studies have analysed this aspect. Consequently, several questions are still pending, as for example, on what regard the existence/ or not of distinct ASCs subpopulations. The present study is originally aimed at isolating selected ASCs subpopulations, and to analyse their behaviour towards the heterogeneous population regarding the expression of stem cell markers and also regarding their osteogenic and chondrogenic differentiation potential. Human Adipose derived Stem Cells (hASCs) subpopulations were isolated using immunomagnetic beads coated with several different antibodies (CD29, CD44, CD49d, CD73, CD90, CD 105, Stro-1 and p75) and were characterized by Real Time RT-PCR in order to assess the expression of mesenchymal stem cells markers (CD44, CD73, Stro-1, CD105 and CD90) as well as known markers of the chondrogenic (Sox 9, Collagen II) and osteogenic lineage (Osteopontin, Osteocalcin). The obtained results underline the complexity of the ASCs population demonstrating that it is composed of several subpopulations, which express different levels of ASCs markers and exhibit distinctive differentiation potentials. Furthermore, the results obtained clearly evidence of the advantages of using selected populations in cell-based therapies, such as bone and cartilage regenerative medicine approaches.     

Genital Herpes: Review of the Epidemic and Potential Use of Type-Specific Serology

Prevention of genital herpes simplex virus (HSV) infections is desirable from both a public health standpoint and the patient’s perspective. A key factor in the spread of genital herpes infections is the high proportion of undiagnosed infections. Persons with subclinical or unrecognized infections are best diagnosed by accurate, type-specific antibody tests. Unfortunately, these tests are only now becoming widely available. The use of current, conventional (non-type-specific) serologic tests for diagnosis of herpes infections has resulted in confusion and misdiagnosis of patients. This review provides recent information on the epidemiology of genital herpes infections, describes the importance of subclinical herpes infection and shedding, summarizes the status of HSV type-specific serologic assays being developed, and provides indications for using such assays.     

骨髓间充质干细胞向软骨细胞的分化

背景：以骨髓间充质干细胞构建组织工程气管尚缺乏理想的特异性表面标志物,对其鉴定主要依赖细胞形态学、细胞表型及诱导分化的功能进行分析。 目的：体外分离培养、鉴定兔骨髓间充质干细胞,观察在特定条件下向气管软骨细胞分化的潜能。 方法：无菌环境取兔骨髓,经全骨髓贴壁筛选法分离培养细胞至第2代,流式细胞术鉴定第1、第2代细胞表面抗原CD44、CD45的表达。无菌环境取气管,经酶消化法分离培养气管软骨细胞,甲苯胺蓝染色鉴定软骨细胞蛋白聚糖的合成。在使用转化生长因子β1的基础上,将骨髓间充质干细胞与气管软骨细胞通过Transwell小室非接触式共培养,倒置显微镜观察细胞形态,甲苯胺蓝染色鉴定蛋白聚糖的合成,荧光实时定量PCR鉴定Ⅱ型胶原和蛋白聚糖 mRNA的表达。 结果与结论：分离、培养的细胞呈长梭形、不规则形聚集生长,传代后细胞生长速度明显增快,呈鱼群状聚集生长。第1代有96.97%的细胞表达CD44、13.72%的细胞表达CD45,第2代有99.11%的细胞表达CD44、8.54%的细胞表达CD45。气管软骨细胞甲苯胺蓝染色阳性。在诱导后,骨髓间充质干细胞形态逐渐由长梭形变为三角形或不规则形,表达软骨细胞特异性Ⅱ型胶原和蛋白聚糖 mRNA基因,甲苯胺蓝染色示阳性。结果表明全骨髓贴壁筛选法可成功分离培养骨髓间充质干细胞,第2代纯度较高,且在特定诱导条件下具有分化为气管软骨细胞的潜能。     

Vaccination-Induced Circulation of Human B Cells Secreting Type-Specific Antibodies against Pneumococcal Polysaccharides

Indirect plaque-forming cell assays detecting B cells secreting antibodies against capsular pneumococcal polysaccharide (PPS) antigens are described. In healthy adult volunteers the total number of B cells secreting IgM antibodies against the antigens in a polyvalent PPS vaccine reached a maximum in the blood 6 days after in vivo immunization (mean: 552/10(6) mononuclear cells), whereas the highest concentration of IgG and IgA antibody-secreting cells (SC) were detected 7 days after immunization (means: 628 and 1691/10(6]. B cells secreting antibodies to PPS type 3 (PPS3), PPS8, PPS18C and C-polysaccharide (CPS)--a cell wall antigen common to all pneumococci--constituted 9%, 16%, 6% and 5% (means) of the total number of antibody SC respectively. While the majority of the anti-PPS-SC secreted IgA antibodies, the anti-CPS-SC almost exclusively secreted IgG. Pre-vaccination concentrations of anti-PPS were generally low in contrast to antibodies against CPS, which were present in high concentrations in all individuals. The discrepancy in the Ig class of the antibody SC is probably related to the difference in the pre-vaccination immunity against PPS and CPS.     

胎盘来源间充质干细胞的体外诱导成软骨分化

背景：胎盘间充质干细胞已被证实有较强的增殖能力,且能向成骨细胞、成神经细胞、类肝样细胞等诱导分化,但对其成软骨细胞诱导分化的研究不多。 目的：在体外诱导人胎盘间充质干细胞成软骨细胞分化。 方法：体外培养人胎盘间充质干细胞并鉴定。取第3代胎盘间充质干细胞,调整细胞悬液浓度为1.6×1010 L-1,在24孔板中央分别滴5,10,15 μL细胞悬液,培养2 h(目的是形成微团);然后加入间充质干细胞培养基或软骨诱导培养基培养14 d,阿利新蓝染色,进行大体观察及倒置显微镜观察。 结果与结论：应用间充质干细胞培养基培养的对照组,细胞增殖形成大量贴壁细胞,贴壁细胞具有典型的间充质细胞形态;应用软骨诱导培养基培养后,细胞只保持微团,不继续增殖形成贴壁细胞,微团基部无贴壁细胞,随着接种细胞数量的增加,微团直径增大。说明人胎盘来源间充质干细胞具有向软骨细胞分化的能力,可作为组织工程、细胞治疗等应用的种子细胞来源。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：     

Chondrogenic Differentiation of Amniotic Fluid Stem Cells and Their Potential for Regenerative Therapy

Chronic articular cartilage defects are the most common disabling conditions of humans in the western world. The incidence for cartilage defects is increasing with age and the most prominent risk factors are overweight and sports associated overloading. Damage of articular cartilage frequently leads to osteoarthritis due to the aneural and avascular nature of articular cartilage, which impairs regeneration and repair. Hence, patients affected by cartilage defects will benefit from a cell-based transplantation strategy. Autologous chondrocytes, mesenchymal stem cells and embryonic stem cells are suitable donor cells for regeneration approaches and most recently the discovery of amniotic fluid stem cells has opened a plethora of new therapeutic options. It is the aim of this review to summarize recent advances in the use of amniotic fluid stem cells as novel cell sources for the treatment of articular cartilage defects. Molecular aspects of articular cartilage formation as well as degeneration are summarized and the role of growth factor triggered signaling pathways, scaffolds, hypoxia and autophagy during the process of chondrogenic differentiation are discussed.     

iPS细胞的生成——转录因子的决定性作用

胚胎干细胞（Embryonic Stem cells,ESCs）具有分化全能性和自我更新能力,其全能性的维持取决于多种转录因子、表观修饰因子等组成的错综复杂的网络,在这其中Oct4、Sox2、Nanog被认为是核心调控因子。2006年,日本京都大学Yamanaka实验室将Oct4、Sox2、c—Myc和Klf4导入小鼠胚胎成纤维细胞（embryonic fibroblasts,MEFs）中,成功的获得了与小鼠ESCs在表型、生长特性、     

Engineering vascular tissue with functional smooth muscle cells derived from human iPS cells and nanofibrous scaffolds

Tissue-engineered blood vessels (TEBVs) are promising in the replacement of diseased vascular tissues. However, it remains a great challenge to obtain a sufficient number of functional smooth muscle cells (SMCs) in a clinical setting to construct patient-specific TEBVs. In addition, it is critical to develop a scaffold to accommodate these cells and retain their functional phenotype for the regeneration of TEBVs. In this study, human induced pluripotent stem cells (iPSCs) were established from primary human aortic fibroblasts, and characterized with the pluripotency markers expression and cells' capabilities to differentiate into all three germ layer cells. A highly efficient method was then developed to induce these human iPSCs into proliferative SMCs. After multiple times of expansion, the expanded SMCs retained the potential to be induced into the functional contractile phenotype of mature SMCs, which was characterized by the contractile response to carbachol treatment, up-regulation of specific collagen genes under transforming growth factor β1 treatment, and up-regulation of specific matrix metalloproteinase genes under cytokine stimulation. We also developed an advanced macroporous and nanofibrous (NF) poly(l-lactic acid) (PLLA) scaffold with suitable pore size and interpore connectivity to seed these human iPSC-derived SMCs and maintain their differentiated phenotype. Subcutaneous implantation of the SMC-scaffold construct in nude mice demonstrated vascular tissue formation, with robust collagenous matrix deposition inside the scaffold and the maintenance of differentiated SMC phenotype. Taken together, this study established an exciting approach towards the construction of patient-specific TEBVs. We established patient-specific human iPSCs, derived proliferative SMCs for expansion, turned on their mature contractile SMC phenotype, and developed an advanced scaffold for these cells to regenerate vascular tissue in vivo.     

Chondrogenic differentiation of adult mesenchymal stem cells and embryonic cells in collagen scaffolds

Many cell types and cellular microenvironments have been explored for articular cartilage tissue engineering. We compared the potential of bone marrow-derived mesenchymal stem cells (MSCs) and P19 embryonic carcinoma cells (ECCs), a pluripotent derivative of embryonic stem cells (ESCs), for cartilage histogenesis in porous collagen scaffolds in vitro. We found that while both MSCs and ECCs express α-smooth muscle actin (α-SMA), only MSCs exhibit condensation and contraction necessary for cartilage histogenesis. Furthermore, histology confirmed that only MSCs exhibited sulfated glycosaminoglycans and collagen type II formation after 14 days in culture. We conclude that MSCs appear to be superior over ECCs for cartilage regeneration under particular culture conditions. The α-SMA-expressing ECCs may not have contracted due to the absence of actin unit polymerization or the absence of myosin molecules. Our observations may explain the absence of a contractile scar in fetal wound healing.     

Loss of ADAR1 in human iPS cells promotes caspase3‐mediated apoptotic cell death

Adenosine deaminases acting on RNA (ADARs) convert adenosine residues to inosine specifically in double‐stranded RNAs. In this study, we investigated the function of primary RNA editing enzyme ADAR1 in pluripotent stem cells and found that loss of ADAR1 in human iPS cells promotes caspase3‐mediated cell death. However, ADAR1 knockdown (KD) did not alter cell morphology, alkaline phosphatase (AP) staining activities and the expression levels of pluripotent marker genes, indicating that ADAR1 is dispensable for maintenance of pluripotency. Furthermore, ADAR1‐KD iPS cells did not change proliferation rate. These findings extended the role of ADAR1 and might open the road for understanding pluripotent state more deeply.     

Visualization of sequential conversion of human intermediately reprogrammed stem cells into iPS cells

Analysis of gene expression in single cells is required to understand somatic cell reprogramming into human induced pluripotent stem cells (iPSCs). To facilitate this, we established intermediately reprogrammed stem cells (iRSCs), pre‐iPSC lines. The iRSC‐iPSC conversion system enables the reproducible monitoring of reprogramming events and the analysis of progressive gene expression profiles using single‐cell microarray analysis and genome editing. Here, single‐cell microarray analysis showed the stage‐specific sequential gene activation during the conversion of iRSCs into iPSCs, using OCT4, TDGF1 and E‐CADHERIN as marker genes. Out of 75 OCT4‐related genes, which were significantly up‐regulated after the activation of OCT4, and entry into the mesenchymal‐to‐epithelial transition (MET), LIN28 (LIN28A) and FOXO1 were selected for applying to gene expression visualization. Multicolored visualization was achieved by the genome editing of LIN28 or FOXO1 with mCherry into OCT4‐GFP iRSCs. Fluorescent analysis of gene activity in individual cells showed that OCT4 was dispensable for maintenance, but required for activation, of the LIN28 and FOXO1 expression in reprogramming.     

An Improved Technique for Chromosomal Analysis of Human ES and iPS Cells

Prolonged in vitro culture of human embryonic stem (hES) cells can result in chromosomal abnormalities believed to confer a selective advantage. This potential occurrence has crucial implications for the appropriate use of hES cells for research and therapeutic purposes. In view of this, time-point karyotypic evaluation to assess genetic stability is recommended as a necessary control test to be carried out during extensive ‘passaging’. Standard techniques currently used for the cytogenetic assessment of ES cells include G-banding and/or Fluorescence in situ Hybridization (FISH)-based protocols for karyotype analysis, including M-FISH and SKY. Critical for both banding and FISH techniques are the number and quality of metaphase spreads available for analysis at the microscope. Protocols for chromosome preparation from hES and human induced pluripotent stem (hiPS) cells published so far appear to differ considerably from one laboratory to another. Here we present an optimized technique, in which both the number and the quality of chromosome metaphase spreads were substantially improved when compared to current standard techniques for chromosome preparations. We believe our protocol represents a significant advancement in this line of work, and has the required attributes of simplicity and consistency to be widely accepted as a reference method for high quality, fast chromosomal analysis of human ES and iPS cells.     

Differences in Surface Marker Expression and Chondrogenic Potential among Various Tissue-Derived Mesenchymal Cells from Elderly Patients with Osteoarthritis

Mesenchymal stem cells (MSCs) are self-renewing, multipotent cells that could potentially be used to repair injured cartilage in diseases such as osteoarthritis (OA). In this study we used bone marrow, adipose tissue from articular and subcutaneous locations, and synovial fluid samples from 18 patients with knee OA to find a suitable alternative source for the isolation of MSCs with high chondrogenic potential. MSCs from all tissues analysed had a fibroblastic morphology, but their rates of proliferation varied. Subcutaneous fat-derived MSCs proliferated faster than bone marrow- and Hoffa's fat pad-derived MSCs, while synovial fluid-derived MSCs grew more slowly. CD36 and CD54 expression was similar across all groups of MSCs with several minor differences. High expression of these surface markers in subcutaneous fat-derived MSCs was correlated with poor differentiation into hyaline cartilage. Synovial fluid-derived MSCs presented a relatively small chondrogenic differentiation capacity while Hoffa's fat pad-derived MSCs had strong chondrogenic potential. In conclusion, MSCs from elderly patients with OA may still display significant chondrogenic potential, depending on their origin.     

The generation of iPS cells using non-viral magnetic nanoparticle based transfection

Induced pluripotent stem (iPS) cells have been generated from various somatic cells; however, a major restriction of the technology is the use of potentially harmful genome-integrating viral DNAs. Here, without a viral vector, we generated iPS cells from fibroblasts using a non-viral magnetic nanoparticle-based transfection method that employs biodegradable cationic polymer PEI-coated super paramagnetic nanoparticles (NP). Our findings support the possible use of transient expression of iPS genes in somatic cells by magnet-based nanofection for efficient generation of iPS cells. Results of dynamic light scattering (DLS) analysis and TEM analyses demonstrated efficient conjugation of NP with iPS genes. After transfection, nanofection-mediated iPS cells showed ES cell-like characteristics, including expression of endogenous pluripotency genes, differentiation of three germ layer lineages, and formation of teratomas. Our results demonstrate that magnet-based nanofection may provide a safe method for use in generation of virus-free and exogenous DNA-free iPS cells, which will be crucial for future clinical applications in the field of regenerative medicine.     

Three-dimensional growth of iPS cell-derived smooth muscle cells on nanofibrous scaffolds

Induced pluripotent stem cells (iPSCs) have been considered as the major component for personalized regenerative medicine. However, the potential of iPSCs in constructing tissue-engineered (TE) blood vessels has not been exploited. In the present study, we generated mouse iPSCs with the combination of over-expression of 4 iPS factors and knock-down of p53 gene. The established iPSCs were then directed to differentiate into smooth muscle cells (SMCs) with the treatment of 10(-5) (M) all-trans retinoid acid (RA). The vehicle dimethyl sulfoxide (DMSO) treatment served as a spontaneous differentiation control. The differentiated cells were then cultured on three-dimensional (3D) macro-porous nanofibrous (NF) poly(L-lactide) (PLLA) scaffolds in vitro. Our data showed that the expression of SMC specific marker genes, including myocardin, smoothelin, SM22α and SMMHC, were higher for the group induced by RA than for the group treated by DMSO, while pluripotent marker gene expression was repressed by the RA-treatment. Upon subcutaneous implantation, the implanted cells maintained the SMC phenotype. In conclusion, the data suggest that iPSCs-derived SMCs can be an important cell source for personalized vascular tissue engineering applications.     

基底膜基质/壳聚糖诱导骨髓间充质干细胞成软骨分化

背景：课题组前期研究发现基底膜基质能够定向诱导骨髓间充质干细胞向软骨方向分化,但其力学性能与实际应用有较大差距,还需要进一步研究。 目的：制备兼具适宜力学性能和优异生物相容性的壳聚糖/基底膜基质水凝胶支架用于软骨修复。 方法：以京尼平为交联剂,将壳聚糖溶液与基底膜基质按2︰1,1︰1,1︰3比例混合制成水凝胶,接种大鼠骨髓间充质干细胞,培养14 d。经材料力学测试、细胞增殖、活细胞染色、酶联免疫吸附测试以及阿尔新蓝染色等方法评价材料诱导细胞成软骨分化能力。 结果与结论：在基底膜基质内添加壳聚糖后,材料力学性能从0.48 kPa上升到1.78 kPa。标志性蛋白分泌结果显示,纯壳聚糖组早期诱导成软骨活性高于其他组,但后期诱导能力减弱,而含基底膜基质各组在后期能够保持较好的诱导活性,其中壳聚糖/基底膜基质=1︰1组材料具有一定的力学强度,且Ⅱ型胶原和Ⅹ型胶原的表达量在14 d较其他组高。结果表明实验制备的壳聚糖/基底膜基质水凝胶具有良好的力学性能,并能够促进骨髓间充质干细胞向软骨方向分化,可用于软骨组织工程研究。 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：     

Chondrogenic differentiation of human mesenchymal stem cells in three-dimensional alginate gels

We characterized the temporal changes in chondrogenic genes and developed a staging scheme for in vitro chondrogenic differentiation of human mesenchymal stem cells (hMSCs) in three-dimensional (3D) alginate gels. A time-dependent accumulation of glycosaminoglycans, aggrecan, and type II collagen was observed in chondrogenic but not in basal constructs over 24 days. qRT-PCR demonstrated a largely characteristic temporal pattern of chondrogenic markers and provided a basis for staging the cellular phenotype into four stages. Stage I (days 0-6) was defined by collagen types I and VI, Sox 4, and BMP-2 showing peak expression levels. In stage II (days 6-12), gene expression for cartilage oligomeric matrix protein, HAPLN1, collagen type XI, and Sox 9 reached peak levels, while gene expression of matrilin 3, Ihh, Homeobox 7, chondroadherin, and WNT 11 peaked at stage III (days 12-18). Finally, cells in stage IV (days 18-24) attained peak levels of aggrecan; collagen IX, II, and X; osteocalcin; fibromodulin; PTHrP; and alkaline phosphatase. Gene profiles at stages III and IV were analogous to those in juvenile articular and adult nucleus pulposus chondrocytes. Gene ontology analyses also demonstrated a specific expression pattern of several putative novel marker genes. These data provide comprehensive insights on chondrogenesis of hMSCs in 3D gels. The derivation of this staging scheme may aid in defining maximally responsive time points for mechanobiological modulation of constructs to produce optimally engineered tissues.