间充质干细胞与神经细胞移植

间充质干细胞具有跨胚层分化潜能，在适宜条件下可以转化为神经细胞，并对脑缺血，脑外伤和脊髓损伤等疾病的神经功能缺损有改善作用，是神经细胞移植的理想供体，文章就间充质干细胞在神经细胞移植中的研究进展作了综述。     

骨质疏松与间充质干细胞

骨髓间充质干细胞（MSCs）具有自我更新和多向分化潜能,在成年人的骨骼中它主要分化为成骨细胞和脂肪细胞。随着年龄增长,MSCs发生老化,其细胞分化方向改变,致使成骨细胞生成减少,脂肪细胞生成增多,这可能是骨质疏松（OP）的原因之一。通过移植健康的MSCs重建造骨能力,将为OP的防治提供新的思路和方法。     

脂肪间充质干细胞向肝细胞横向分化的研究

目的探讨脂肪源性间充质干细胞（AMSC）向肝细胞横向分化的可能性。方法胶原酶消化脂肪组织,贴壁培养,体外扩增后以流式细胞仪鉴定其表面标志。取扩增3代的AMSC分为2组,诱导分化组在含有2％FBS的DMEM-F12培养基中加入肝细胞生长因子20 ng/ml和成纤维细胞生长因子4 10 ng/ml、1×ITS和地塞米松0．1μmol/L,培养14 d；空白对照组则不加任何细胞因子。RT-PCR检测诱导分化过程中肝细胞核因子1、GATA4等基因转录水平的变化。2周后,采用流式细胞术检测AFP和Alb阳性细胞在两组细胞中的比例,检测肝细胞特异性细胞角蛋白（CK） 18、CK19的表达。结果分离、培养的AMSC呈成纤维细胞样生长,可以稳定传代。流式细胞术检测结果显示第3代脂肪间充质干细胞高表达表面CD29、CD44；不表达CD34、CD45。RT-PCR检测诱导5、8、11、14 d的细胞,显示有肝细胞特异性转录因子GATA4和肝细胞核因子1A基因的表达,并随时间延长而逐渐增多。流式细胞术检测诱导14 d的细胞,发现30．0％的细胞表达Alb,17．8％细胞表达AFP,双阳性的细胞为6．9％；免疫荧光检测发现诱导细胞表达CK18、CK19。空白对照组脂肪间充质干细胞则未见上述各项变化。结论在低血清培养体系中,采用细胞因子联合诱导,显示脂肪间充质细胞在体外能定向分化为肝细胞样细胞。     

脂肪间充质干细胞在心肌梗死治疗的研究进展

脂肪间充质干细胞（ adipose-derived mesenchymal stem cells ,ADSCS）是成体间充质干细胞的一种,来源丰富,全身各组织器官均可,取材方便,对人体创伤小,并且具有同其他干细胞（如骨髓间充质干细胞、脐血干细胞等）类似的多向分化潜能。心肌梗死是目前人类疾病中发病率及病死率高的病种,细胞治疗在这一领域中有很高价值,脂肪间充质干细胞因取材方便及多向分化潜能具有很大的应用前景,脂肪间充质干细胞在心肌梗死治疗中的对心肌保护机制成为一个研究热点。     

晚期糖基化终产物通过氧化应激引起人骨髓间充质干细胞凋亡

目的 观察不同剂量晚期糖基化牛血清白蛋白(AGE-BSA)对体外分离培养的人骨髓间充质干细胞增殖、凋亡及氧化应激的影响,为临床上提高干细胞移植治疗糖尿病心肌病后供体干细胞的存活率提供新的依据.方法 采用全骨髓法从人的骨髓标本中分离培养骨髓间充质干细胞,以含10%FCS的L-DMEM 培养细胞,0.25%的胰酶消化后按1:2 比例传代接种培养,对第3代细胞应用流式细胞仪检测细胞表面标志CD44、CD105和CD34.在骨髓间充质干细胞中加入不同浓度的AGE-BSA,作用24 h后加入CCK-8溶液,37℃5%CO2培养箱培养1 h,用酶标仪在450 nm处测定吸光度值.采用Annexin V/PI 双染法进行染色,避光作用20 min后,将细胞置于流式细胞仪上检测细胞凋亡率.同时对细胞内活性氧水平进行测定,并且测定细胞内的丙二醛含量和超氧化物歧化酶活性.结果 传代后的骨髓间充质干细胞呈鱼群样或漩涡状排列,细胞为长梭形,贴壁紧密,形态较为一致.细胞表面标志CD105(间充质干细胞相对特异性标志)及CD44(黏附分子,基质细胞表达)呈阳性表达,阳性率分别为98.9%、97.8%;CD34(造血干细胞/祖细胞及内皮细胞阳性)呈阴性表达,表达百分率为0.8%.与对照组相比,20、50、100和200 mg/L AGE-BSA均不同程度地抑制骨髓间充质干细胞的增殖,促进其凋亡,随着作用浓度的增加,细胞内活性氧含量、丙二醛含量明显增加,而细胞匀浆中超氧化物歧化酶的活性却受到了抑制,具有剂量依赖效应.结论 晚期糖基化终产物通过促进骨髓间充质干细胞内活性氧生成、减少抗氧化酶生成,增强氧化应激,破坏细胞内环境稳定性,从而抑制骨髓间充质干细胞增殖,促进细胞凋亡.     

间充质干细胞与神经细胞移植

间充质干细胞具有跨胚层分化潜能,在适宜条件下可以转化为神经细胞,并对脑缺血、脑外伤和脊髓损伤等疾病的神经功能缺损有改善作用,是神经细胞移植的理想供体。文章就间充质干细胞在神经细胞移植中的研究进展作了综述。     

洛伐他汀抑制大鼠骨髓间充质干细胞凋亡的实验研究

目的体外以缺氧无血清条件模拟心肌梗死后的心脏缺血微环境,研究洛伐他汀是否能够抑制缺氧无血清引起的骨髓间充质干细胞（MSCs）凋亡。方法以Hoechst33342染色法及AnnexinV／PI流式细胞术检测洛伐他汀的抗凋亡作用,检测线粒体膜电位变化,进一步采用Western blot方法检测洛伐他汀对细胞色素C释放及caspase-3活化的影响。结果洛伐他汀0．01～1μmol／L能够有效地抑制缺氧无血清引起的MSCs凋亡。洛伐他汀抑制线粒体凋亡途径,增强线粒体膜电位水平、抑制细胞色素C释放,降低caspase-3活化水平。结论洛伐他汀能够抑制线粒体途径介导的凋亡,阻止caspase-3的活化,发挥抗缺氧无血清引起的MSCs凋亡,为提高移植干细胞的存活率提供了一种可能有效的干预措施。     

间充质干细胞与肺

间充质干细胞(MSC)是一类自我更新能力强、细胞特性稳定、具有多分化潜能的成体干细胞,广泛存在于人骨髓、肝、脾、肺等多种组织和器官中.本文综述了MSC的生物学特性和临床应用前景,并着重阐述肺部MSC的特点,对近年来MSC与各类常见肺部疾病的相关研究作一回顾.     

骨髓间充质干细胞归巢研究进展

骨髓问充质干细胞（BMMSCs）,是一种多能干细胞,具有多向分化潜能,可分化为骨细胞、软骨细胞、内皮细胞、心肌细胞等,并能分泌大量细胞因子,参与组织修复。因此,BMMSCs成为科研工作者研究的热点和焦点,并取得了不少令人欣喜的成果,但是其到底是怎么归巢到靶器官,仍不是很清楚。本文就BMMSCs归巢的机制和影响因素进行简要综述。     

间充质干细胞在缺血缺氧环境中的存活情况

生理条件下间充质干细胞(MSCs)内的氧浓度低于外界正常氧浓度,处于相对低氧状态;移植到体内的MSCs所处生存环境因损伤、缺血导致氧浓度更低,这种缺血缺氧环境对MSCs生存造成极大影响。缺血缺氧环境下,MSCs会启动自身抗凋亡机制维持细胞的存活率。此外,低氧预处理、药物应用、充足的葡萄糖供给、部分细胞因子的添加和基因工程技术的应用也可不同程度地促进缺血缺氧环境中MSCs的生存。     

支链氨基酸氨基转移酶1通过核因子E2相关因子2调节缺氧/复氧损伤相关的心肌细胞铁死亡

目的 研究支链氨基酸转移酶（branched-chain amino acid aminotransferase 1,BCAT1）调节心肌细胞铁死亡和缺氧/复氧损伤的作用及机制。方法 分离Sprague Dawley乳鼠心室肌细胞（neonatal rat ventricular myocytes,NRVMs）并培养。利用腺病毒载体转染NRVMs分别敲低或过表达BCAT1后给予NRVMs缺氧/复氧（hypoxia/reoxygenation,H/R）损伤或给予Erastin诱导其铁死亡。给予核因子E2相关因子2(nuclear factor erythroid 2-related factor-2,NRF2)特异性抑制剂ML385探讨NRF2在BCAT1调节NRVMs铁死亡中的作用。结果 敲低BCAT1表达加重H/R诱导的NRVMs死亡和脂质过氧化,而敲低BCAT1加重损伤的现象可被铁死亡抑制剂Ferr-1基本消除。过表达BCAT1可以减轻H/R和Erastin诱导的心肌细胞死亡和脂质过氧化。过表达BCAT1显著上调NRF2蛋白表达和下游抗氧化应激基因Ho-1、Nqo-1和Trx-1 ...     

Branched chain amino acid metabolism in the retina of diabetic rats

Summary Diabetes is known to produce increased levels of the branched chain amino acids in plasma, heart and muscle as well as increased oxidation of [¹⁴C]-leucine by nerves and muscles from rats. Plasma and retinas from streptozotocin diabetic rats had significant elevations in branched chain amino acid levels compared to control. Retinas from diabetic rats have been found to oxidize significantly more of the branched chain amino acids, leucine, isoleucine and valine than did control retinas when incubated in media containing 16.5 mmol/1 glucose. Neither the extracellular space nor the tissue pool of leucine was significantly different in the two groups. The addition of 19 amino acids, at normal plasma concentrations, to the incubation media resulted in 80 percent suppression of leucine oxidation without significant change in incorporation of [¹⁴C] into protein. These results suggest that the major role for the branched chain amino acids in the rat retina is in protein synthesis which is not affected by short-term diabetes.This investigation was supported by a grant-in-aid from Fight-For-Sight, Inc., New York City, and by USPHS grant AM02001 from the National Institute of Arthritis, Metabolism and Digestive Diseases.     

Three-amino-acid-loop-extension homeodomain factor Meis3 regulates cell survival via PDK1

Three-amino-acid-loop-extension (TALE) homeodomain proteins including Meis and Pbx families are generally recognized for their roles in growth and differentiation during vertebrate embryogenesis and tumorigenesis. Whereas genetic studies indicate that Pbx1 regulates the development and function of insulin-producing pancreatic β-cells, the role of Meis family members in β-cells is still unknown. Here we show that Meis3 is abundantly expressed in pancreatic islets and β-cells and that it regulates β-cell survival. We further identify the 3-phosphoinositide-dependent protein kinase 1 (PDK1), a well-known kinase involved in the PI3K-Akt signaling pathway, as a direct Meis3 target, which mediates its role in β-cell survival. This regulatory module appears to function broadly as we also identify Meis3 regulation of cell survival and PDK1 expression in ovarian carcinoma cells, suggesting a unique function for Meis3 beyond the traditional roles for TALE homeodomain factors during embryogenesis.     

Human endothelial colony-forming cells serve as trophic mediators for mesenchymal stem cell engraftment via paracrine signaling

Endothelial colony-forming cells (ECFCs) are endothelial precursors that circulate in peripheral blood. Studies have demonstrated that human ECFCs have robust vasculogenic properties. However, whether ECFCs can exert trophic functions in support of specific stem cells in vivo remains largely unknown. Here, we sought to determine whether human ECFCs can function as paracrine mediators before the establishment of blood perfusion. We used two xenograft models of human mesenchymal stem cell (MSC) transplantation and studied how the presence of ECFCs modulates MSC engraftment and regenerative capacity in vivo. Human MSCs were isolated from white adipose tissue and bone marrow aspirates and were s.c. implanted into immunodeficient mice in the presence or absence of cord blood-derived ECFCs. MSC engraftment was regulated by ECFC-derived paracrine factors via platelet-derived growth factor BB (PDGF-BB)/platelet-derived growth factor receptor (PDGFR)-β signaling. Cotransplanting ECFCs significantly enhanced MSC engraftment by reducing early apoptosis and preserving stemness-related properties of PDGFR-β⁺ MSCs, including the ability to repopulate secondary grafts. MSC engraftment was negligible in the absence of ECFCs and completely impaired in the presence of Tyrphostin AG1296, an inhibitor of PDGFR kinase. Additionally, transplanted MSCs displayed fate-restricted potential in vivo, with adipose tissue-derived and bone marrow-derived MSCs contributing exclusive differentiation along adipogenic and osteogenic lineages, respectively. This work demonstrates that blood-derived ECFCs can serve as paracrine mediators and regulate the regenerative potential of MSCs via PDGF-BB/PDGFR-β signaling. Our data suggest the systematic use of ECFCs as a means to improve MSC transplantation.Endothelial colony-forming cells (ECFCs) are a subset of progenitor cells that circulate in peripheral blood. The identification of ECFCs in humans created a promising opportunity to noninvasively derive large quantities of autologous endothelial cells (ECs) for clinical use (1–3). Indeed, a growing body of preclinical studies has substantiated the therapeutic potential of ECFCs. Initial demonstrations included using ECFCs to endothelialize cardiovascular grafts as a means to achieve effective antithrombogenicity and vascular patency in vivo (4). Studies have also demonstrated that human blood-derived ECFCs have inherent and robust vasculogenic properties. Following transplantation into immunodeficient mice, ECFCs can self-assemble into long-lasting microvascular networks that anastomose with the host vasculature (5, 6). The function of ECFC-lined microvessels has been shown to be similar to that of normal microvessels in several respects, including nonthrombogenicity, blood flow, regulation of macromolecule permeability, and capacity to induce leukocyte-endothelial interactions in response to cytokine activation (5, 7).Beyond lining cardiovascular structures, ECs regulate multiple physiological processes through the secretion of angiocrine factors (8). During development, the endothelium provides paracrine signals to assist the formation of various organs, including liver and pancreas (9, 10). Emerging evidence indicates that ECs also regulate postnatal homeostatic and regenerative processes via paracrine production of stem cell-active trophic factors (11). For example, signals from bone marrow microvascular ECs are essential for self-renewal and repopulation of hematopoietic stem cells (12). Similarly, EC-derived paracrine signals stimulate self-renewal and in situ expansion of stem cells residing in lung, liver, and neural tissues, contributing to the regeneration of these tissues upon injury (13, 14). Despite this trophic potential, current therapeutic uses of ECFCs remain largely focused on harnessing their inherent blood vessel-forming capacity. However, whether ECFCs can exert trophic functions in support of specific stem cells in vivo is largely unknown.Here, we investigated whether human cord blood-derived ECFCs can function as paracrine mediators before the establishment of blood perfusion. Toward this aim, we used two preclinical xenograft models of human mesenchymal stem cell (MSC) transplantation and studied how the presence of ECFCs modulates MSC engraftment and regenerative capacity in vivo.     

Improved graft mesenchymal stem cell survival in ischemic heart with a hypoxia-regulated heme oxygenase-1 vector.

OBJECTIVES: The goal of this study was to modify mesenchymal stem cells (MSCs) cells with a hypoxia-regulated heme oxygenase-1 (HO-1) plasmid to enhance the survival of MSCs in acute myocardial infarction (MI) heart. BACKGROUND: Although stem cells are being tested clinically for cardiac repair, graft cells die in the ischemic heart because of the effects of hypoxia/reoxygenation, inflammatory cytokines, and proapoptotic factors. Heme oxygenase-1 is a key component in inhibiting most of these factors. METHODS: Mesenchymal stem cells from bone marrow were transfected with either HO-1 or LacZ plasmids. Cell apoptosis was assayed in vitro after hypoxia-reoxygen treatment. In vivo, 1 x 10(6) of male MSC(HO-1), MSC(LacZ), MSCs, or medium was injected into mouse hearts 1 h after MI (n = 16/group). Cell survival was assessed in a gender-mismatched transplantation model. Apoptosis, left ventricular remodeling, and cardiac function were tested in a gender-matched model. RESULTS: In the ischemic myocardium, the MSC(HO-1) group had greater expression of HO-1 and a 2-fold reduction in the number of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate in situ nick end labeling-positive cells compared with the MSC(LacZ) group. At seven days after implantation, the survival MSC(HO-1) was five-fold greater than the MSC(LacZ) group; MSC(HO-1) also attenuated left ventricular remodeling and enhanced the functional recovery of infarcted hearts two weeks after MI. CONCLUSIONS: A hypoxia-regulated HO-1 vector modification of MSCs enhances the tolerance of engrafted MSCs to hypoxia-reoxygen injury in vitro and improves their viability in ischemic hearts. This demonstration is the first showing that a physiologically inducible vector expressing of HO-1 genes improves the survival of stem cells in myocardial ischemia.     

IGF-1-overexpressing mesenchymal stem cells accelerate bone marrow stem cell mobilization via paracrine activation of SDF-1alpha/CXCR4 signaling to promote myocardial repair

We hypothesized that mesenchymal stem cells (MSCs) overexpressing insulin-like growth factor (IGF)-1 showed improved survival and engraftment in the infarcted heart and promoted stem cell recruitment through paracrine release of stromal cell-derived factor (SDF)-1alpha. Rat bone marrow-derived MSCs were used as nontransduced ((Norm)MSCs) or transduced with adenoviral-null vector ((Null)MSCs) or vector encoding for IGF-1 ((IGF-1)MSCs). (IGF-1)MSCs secreted higher IGF-1 until 12 days of observation (P<0.001 versus (Null)MSCs). Molecular studies revealed activation of phosphoinositide 3-kinase, Akt, and Bcl.xL and inhibition of glycogen synthase kinase 3beta besides release of SDF-1alpha in parallel with IGF-1 expression in (IGF-1)MSCs. For in vivo studies, 70 muL of DMEM without cells (group 1) or containing 1.5x10(6) (Null)MSCs (group 2) or (IGF-1)MSCs (group 3) were implanted intramyocardially in a female rat model of permanent coronary artery occlusion. One week later, immunoblot on rat heart tissue (n=4 per group) showed elevated myocardial IGF-1 and phospho-Akt in group 3 and higher survival of (IGF-1)MSCs (P<0.06 versus (Null)MSCs) (n=6 per group). SDF-1alpha was increased in group 3 animal hearts (20-fold versus group 2), with massive mobilization and homing of ckit(+), MDR1(+), CD31(+), and CD34(+) cells into the infarcted heart. Infarction size was significantly reduced in cell transplanted groups compared with the control. Confocal imaging after immunostaining for myosin heavy chain, actinin, connexin-43, and von Willebrand factor VIII showed extensive angiomyogenesis in the infarcted heart. Indices of left ventricular function, including ejection fraction and fractional shortening, were improved in group 3 as compared with group 1 (P<0.05). In conclusion, the strategy of IGF-1 transgene expression induced massive stem cell mobilization via SDF-1alpha signaling and culminated in extensive angiomyogenesis in the infarcted heart.