Isolation and Animal Serum Free Expansion of Human Umbilical Cord Derived Mesenchymal Stromal Cells (MSCs) and Endothelial Colony Forming Progenitor Cells (ECFCs)

The umbilical cord is a rich source for progenitor cells with high proliferative potential including mesenchymal stromal cells (also termed mesenchymal stem cells, MSCs) and endothelial colony forming progenitor cells (ECFCs). Both cell types are key players in maintaining the integrity of tissue and are probably also involved in regenerative processes and tumor formation.To study their biology and function in a comparative manner it is important to have both cells types available from the same donor. It may also be beneficial for regenerative purposes to derive MSCs and ECFCs from the same tissue.Because cellular therapeutics should eventually find their way from bench to bedside we established a new method to isolate and further expand progenitor cells without the use of animal protein. Pooled human platelet lysate (pHPL) replaced fetal bovine serum in all steps of our protocol to completely avoid contact of the cells to xenogeneic proteins.This video demonstrates a methodology for the isolation and expansion of progenitor cells from one umbilical cord.All materials and procedures will be described.Download video file.^{(185M, mp4)}     

Comparison of Fibronectin and Collagen in Supporting the Isolation and Expansion of Endothelial Progenitor Cells from Human Adult Peripheral Blood

Background

Endothelial colony-forming cells (ECFCs), are circulating endothelial progenitor cells increasingly studied in various diseases because of their potential for clinical translation. Experimental procedures for their ex vivo culture still lack standardization. In particular two different extracellular matrix proteins, either fibronectin or collagen, are commonly used by different Authors for coating plastic plates, both allowing to obtain cells that have all the features of ECFCs. However, possible differences in the impact of each substrate on ECFCs have not been analysed, so far. Therefore, in this study we investigated whether fibronectin and collagen may differentially affect ECFC cultures.

Methodology/Principal Findings

ECFCs were isolated and cultured from peripheral blood mononuclear cells of healthy donors. The impact of fibronectin compared with collagen as the only variable of the experimental procedure was analysed separately in the phase of isolation of ECFC colonies and in the following phase of cell expansion. In the isolation phase, although similar frequencies of colonies were obtained on the two substrates, ECFC colonies appeared some days earlier when mononuclear cells were seeded on fibronectin rather than collagen. In the expansion phase, ECFCs cultured on collagen showed a longer lifespan and higher cell yields compared with ECFCs cultured on fibronectin, possibly related to the higher levels of IL-6 and IL-8 measured in their supernatants. ECFCs cultured on both substrates showed similar immunophenotype and ability for in vitro tube formation.

Conclusions/Significance

Overall, the results of this study indicate that, although both fibronectin and collagen efficiently sustain ECFC cultures, each of them brings some advantages within individual steps of the entire process. We suggest that colony isolation performed on fibronectin followed by cell expansion performed on collagen may represent a novel and the most efficient strategy to obtain ECFCs from adult peripheral blood samples.     

Human Endothelial Progenitor Cells Internalize High-Density Lipoprotein

Endothelial progenitor cells (EPCs) originate either directly from hematopoietic stem cells or from a subpopulation of monocytes. Controversial views about intracellular lipid traffic prompted us to analyze the uptake of human high density lipoprotein (HDL), and HDL-cholesterol in human monocytic EPCs. Fluorescence and electron microscopy were used to investigate distribution and intracellular trafficking of HDL and its associated cholesterol using fluorescent surrogates (bodipy-cholesterol and bodipy-cholesteryl oleate), cytochemical labels and fluorochromes including horseradish peroxidase and Alexa Fluor® 568. Uptake and intracellular transport of HDL were demonstrated after internalization periods from 0.5 to 4 hours. In case of HDL-Alexa Fluor® 568, bodipy-cholesterol and bodipy-cholesteryl oleate, a photooxidation method was carried out. HDL-specific reaction products were present in invaginations of the plasma membrane at each time of treatment within endocytic vesicles, in multivesicular bodies and at longer periods of uptake, also in lysosomes. Some HDL-positive endosomes were arranged in form of “strings of pearl”- like structures. HDL-positive multivesicular bodies exhibited intensive staining of limiting and vesicular membranes. Multivesicular bodies of HDL-Alexa Fluor® 568–treated EPCs showed multilamellar intra-vacuolar membranes. At all periods of treatment, labeled endocytic vesicles and organelles were apparent close to the cell surface and in perinuclear areas around the Golgi apparatus. No HDL-related particles could be demonstrated close to its cisterns. Electron tomographic reconstructions showed an accumulation of HDL-containing endosomes close to the trans-Golgi-network. HDL-derived bodipy-cholesterol was localized in endosomal vesicles, multivesicular bodies, lysosomes and in many of the stacked Golgi cisternae and the trans-Golgi-network Internalized HDL-derived bodipy-cholesteryl oleate was channeled into the lysosomal intraellular pathway and accumulated prominently in all parts of the Golgi apparatus and in lipid droplets. Subsequently, also the RER and mitochondria were involved. These studies demonstrated the different intracellular pathway of HDL-derived bodipy-cholesterol and HDL-derived bodipy-cholesteryl oleate by EPCs, with concomitant.     

内皮祖细胞的分离培养与鉴定

内皮祖细胞的分离方法有免疫磁珠分离法、淋巴细胞分离液分离法(1.077)和差速贴壁法,这3种方法已被人们广泛使用,均可分离到一定的目的细胞。分离到的目的细胞在培养过程中逐渐分化、成熟、发育为内皮细胞。在内皮细胞和内皮祖细胞的鉴别区分,使用CD34+/CD133+/KDR+鉴定为内皮祖细胞,同时使用内皮祖细胞吞噬D il-ac-LDLFITC-UEA双阳性的方法也可鉴定为内皮祖细胞。     

Human Cord Blood-Derived AC133+ Progenitor Cells Preserve Endothelial Progenitor Characteristics after Long Term In Vitro Expansion

Background

Stem cells/progenitors are central to the development of cell therapy approaches for vascular ischemic diseases. The crucial step in rescuing tissues from ischemia is improvement of vascularization that can be achieved by promoting neovascularization. Endothelial progenitor cells (EPCs) are the best candidates for developing such an approach due to their ability to self-renew, circulate and differentiate into mature endothelial cells (ECs). Studies showed that intravenously administered progenitors isolated from bone marrow, peripheral or cord blood home to ischemic sites. However, the successful clinical application of such transplantation therapy is limited by low quantities of EPCs that can be generated from patients. Hence, the ability to amplify the numbers of autologous EPCs by long term in vitro expansion while preserving their angiogenic potential is critically important for developing EPC based therapies. Therefore, the objective of this study was to evaluate the capacity of cord blood (CB)-derived AC133+ cells to differentiate, in vitro, towards functional, mature endothelial cells (ECs) after long term in vitro expansion.

Methodology

We systematically characterized the properties of CB AC133+ cells over the 30 days of in vitro expansion. During 30 days of culturing, CB AC133+ cells exhibited significant growth potential that was manifested as 148-fold increase in cell numbers. Flow cytometry and immunocytochemistry demonstrated that CB AC133+ cells'' expression of endothelial progenitor markers was not affected by long term in vitro culturing. After culturing under EC differentiation conditions, cells exhibited high expression of mature ECs markers, such as CD31, VEGFR-2 and von Willebrand factor, as well as the morphological changes indicative of differentiation towards mature ECs. In addition, throughout the 30 day culture cells preserved their functional capacity that was demonstrated by high uptake of DiI fluorescently conjugated-acetylated-low density lipoprotein (DiI-Ac-LDL), in vitro and in vivo migration towards chemotactic stimuli and in vitro tube formation.

Conclusions

These studies demonstrate that primary CB AC133+ culture contained mainly EPCs and that long term in vitro conditions facilitated the maintenance of these cells in the state of commitment towards endothelial lineage.     

Phenotypic and Functional Characterization of Endothelial Colony Forming Cells Derived from Human Umbilical Cord Blood

Longstanding views of new blood vessel formation via angiogenesis, vasculogenesis, and arteriogenesis have been recently reviewed¹. The presence of circulating endothelial progenitor cells (EPCs) were first identified in adult human peripheral blood by Asahara et al. in 1997 ² bringing an infusion of new hypotheses and strategies for vascular regeneration and repair. EPCs are rare but normal components of circulating blood that home to sites of blood vessel formation or vascular remodeling, and facilitate either postnatal vasculogenesis, angiogenesis, or arteriogenesis largely via paracrine stimulation of existing vessel wall derived cells³. No specific marker to identify an EPC has been identified, and at present the state of the field is to understand that numerous cell types including proangiogenic hematopoietic stem and progenitor cells, circulating angiogenic cells, Tie2⁺ monocytes, myeloid progenitor cells, tumor associated macrophages, and M2 activated macrophages participate in stimulating the angiogenic process in a variety of preclinical animal model systems and in human subjects in numerous disease states^{4, 5}. Endothelial colony forming cells (ECFCs) are rare circulating viable endothelial cells characterized by robust clonal proliferative potential, secondary and tertiary colony forming ability upon replating, and ability to form intrinsic in vivo vessels upon transplantation into immunodeficient mice^6-8. While ECFCs have been successfully isolated from the peripheral blood of healthy adult subjects, umbilical cord blood (CB) of healthy newborn infants, and vessel wall of numerous human arterial and venous vessels ^6-9, CB possesses the highest frequency of ECFCs⁷ that display the most robust clonal proliferative potential and form durable and functional blood vessels in vivo^{8, 10-13}. While the derivation of ECFC from adult peripheral blood has been presented^{14, 15}, here we describe the methodologies for the derivation, cloning, expansion, and in vitro as well as in vivo characterization of ECFCs from the human umbilical CB.     

Isolation and Culture Expansion of Tumor-specific Endothelial Cells

Freshly isolated tumor-specific endothelial cells (TEC) can be used to explore molecular mechanisms of tumor angiogenesis and serve as an in vitro model for developing new angiogenesis inhibitors for cancer. However, long-term in vitro expansion of murine endothelial cells (EC) is challenging due to phenotypic drift in culture (endothelial-to-mesenchymal transition) and contamination with non-EC. This is especially true for TEC which are readily outcompeted by co-purified fibroblasts or tumor cells in culture. Here, a high fidelity isolation method that takes advantage of immunomagnetic enrichment coupled with colony selection and in vitro expansion is described. This approach generates pure EC fractions that are entirely free of contaminating stromal or tumor cells. It is also shown that lineage-traced Cdh5^cre:ZsGreen^l/s/l reporter mice, used with the protocol described herein, are a valuable tool to verify cell purity as the isolated EC colonies from these mice show durable and brilliant ZsGreen fluorescence in culture.     

高效诱导人胚胎干细胞成为内皮祖细胞

血管的发生和发育不仅对胚胎形成中各器官的发育分化十分重要,并且对成体的创伤修复和生殖功能也具有重要意义．血管内皮细胞是形成心血管封闭管道系统的形态基础,体外多种细胞可经诱导分化产生出内皮祖/内皮细胞(endothelial progenitor/endothelial cells,EPCs/ECs),但是存在一些不足．鉴于人类胚胎干细胞(human embryonic stem cells,hESCs)诱导分化的全能性和长期增殖能力,为EPCs/ECs提供了新的来源．现有文献报道,hESCs诱导分化为EPCs/ECs的比例较低,为了提高该诱导分化效率,我们使用分阶段的二维诱导方法,首先将细胞接种在超纯层纤连蛋白(Matrigel)上,之后通过在不同阶段添加不同的因子,最终获得CD31⁺KDR⁺细胞的比例可以达到16%．进一步内皮诱导分化的结果显示,获得的EPCs/ECs的比例可以达到约32%,这些细胞具有在Matrigel上形成血管样结构的能力,可结合植物凝集素．实时定量PCR的结果显示,诱导分化所得的细胞表达众多内皮相关基因,并且免疫荧光的结果也表明部分细胞表达内皮细胞特异性表面标志CD31．     

两种不同内皮祖细胞的分离培养与鉴定

目的:探讨从小鼠骨髓中分离、培养、诱导分化及鉴定两种内皮祖细胞的方法,为进一步研究和临床应用奠定基础。方法:密度梯度离心法分离小鼠骨髓单个核细胞,接种于内皮祖细胞条件培养基,通过贴壁培养法培养出早期内皮祖细胞和晚期内皮祖细胞,并在0 d、6 d、10 d流式鉴定早期内皮祖细胞,在第8周流式鉴定晚期内皮祖细胞。结果:通过体外贴壁扩增培养,从小鼠骨髓细胞中成功培养出EEPC(早期内皮祖细胞)和EOC(晚期内皮祖细胞),表达CD34+/CD133+/VEGFR2+的EEPC比例从最初的0.08%能够增长至70%;EOC大约出现于3-4周,5-8周时呈现指数增长,具有典型的内皮细胞鹅卵石样形态,表达CD31、VEGFR2等内皮细胞表面标志而不表达CD34、CD133等干细胞表面标志。结论:确立了内皮祖细胞体外分离培养和诱导分化的实验方法,为进一步研究奠定基础。     

猪外周血内皮祖细胞的分离培养和鉴定

从猪外周血分离出单个核细胞,置于EGM-2培养基中培养,通过挑选细胞集落并对之进行免疫组织化学染色和荧光染色来鉴定内皮祖细胞。结果显示猪的内皮祖细胞为长梭形或纺锤形并呈集落生长,能够吞噬已酰化低密度脂蛋(ac-LDL)并结合凝结素BS-1,同时具有内皮细胞标志CD31、flk-1和von willebrand factor(vWF)。这些结果表明能够从猪的外周血中分离培养出内皮祖细胞,为自体内皮祖细胞移植促进猪慢性心肌缺血模型血管新生的研究打下了基础。     

人脐带血中内皮克隆形成细胞的分离和培养

目的:脐带血来源的内皮克隆形成细胞具有高度增殖、自我更新和血管生成的能力,是再生医学和母胎医学领域研究的热点。本研究旨在提出一种有效的、可靠的人脐带血中内皮克隆形成细胞分离和培养方法。方法:取抗凝脐血,采用密度梯度离心法分离单核细胞并进行贴壁培养,在细胞克隆形成但未融合成片时,进行单克隆的挑取再培养,最后对所得细胞进行表型和功能的鉴定。结果:所获细胞增殖能力强,形态单一,呈鹅卵石样,连续传代8次,未见细胞性状改变。接种到基质胶上,细胞可连接为管状、网状结构。能摄取培养液中的低密度脂蛋白并结合荆豆凝集素,细胞免疫荧光显示其表达典型的内皮细胞标志性分子CD31、e NOS、VE-Cadherin、v WF。结论:通过本研究的方法,我们从脐带血中获得足够数量和高纯度的内皮克隆形成细胞,这为进一步的实验研究提供了可靠的基础。     

鼠骨髓源性内皮祖细胞的分离培养与鉴定

目的探讨大鼠骨髓源性内皮祖细胞(endothelial progenitor cells,EPCs)的分离培养鉴定的方法.方法 Percoll(1.077 g/ml)分离液分离大鼠骨髓单个核细胞,血管内皮生长因子(Vascular Endothelial Growth Factors, VEGF)和碱性成纤维细胞生长因子(basic Fibroblast Growth Factors, bFGF),对其进行诱导培养,光镜观察EPCs形态,免疫荧光检测血小板内皮细胞粘附分子-1(PECAM-1/CD31)、血管内皮钙粘蛋白(VE-cadherin/CD144)、荆豆凝集素-1(FITC-UEA-1)的表达和摄取Dil荧光标记的乙酰化-低密度脂蛋白(Dil-ac-LDL).结果 诱导培养7 d后,可见集落和铺路石样结构,激光扫描共聚焦显微镜(Laser Scanning Confocal Microscope, LSCM)显示表型为CD31+VE-cadherin+双阳性细胞以及具有内皮细胞功能的Dil-ac-LDL和FITC-UEA-1双染色细胞.结论 采用Percoll(1.077 g/ml)密度梯度离心结合VEGF、bFGF诱导培养可以获得EPCs,说明该培养方法可行.     

Expansion of Endothelial Progenitor Cells in High Density Dot Culture of Rat Bone Marrow Cells

In vitro expansion of endothelial progenitor cells (EPCs) remains a challenge in stem cell research and its application. We hypothesize that high density culture is able to expand EPCs from bone marrow by mimicking cell-cell interactions of the bone marrow niche. To test the hypothesis, rat bone marrow cells were either cultured in high density (2×10⁵ cells/cm²) by seeding total 9×10⁵ cells into six high density dots or cultured in regular density (1.6×10⁴ cells/cm²) with the same total number of cells. Flow cytometric analyses of the cells cultured for 15 days showed that high density cells exhibited smaller cell size and higher levels of marker expression related to EPCs when compared to regular density cultured cells. Functionally, these cells exhibited strong angiogenic potentials with better tubal formation in vitro and potent rescue of mouse ischemic limbs in vivo with their integration into neo-capillary structure. Global gene chip and ELISA analyses revealed up-regulated gene expression of adhesion molecules and enhanced protein release of pro-angiogenic growth factors in high density cultured cells. In summary, high density cell culture promotes expansion of bone marrow contained EPCs that are able to enhance tissue angiogenesis via paracrine growth factors and direct differentiation into endothelial cells.     

内皮祖细胞与血管重新内皮化

血管内皮是循环血液和血管壁组织间的一层天然屏障,在维持血管的正常形态和功能中起重要作用。内皮受损后可引起炎症反应、单核细胞浸润和血管平滑肌细胞增生,促发动脉粥样硬化和再狭窄。因此,直接修复受损血管内皮,促使血管重新内皮化已经成为防止动脉粥样硬化及再狭窄领域的重要课题。大量研究表明,内皮祖细胞(EPC)参与受损血管的重新内皮化。该文就内皮祖细胞的来源、鉴定、参与重新内皮化进行综述。     

MRI-based Visualization of Iron-labeled CD133+ Human Endothelial Progenitor Cells

The objective of this study is to build up a kind of effective approach to multiply CD133+ endothelial progenitor cells (EPCs) and visualize cells by labeling with two FDA-approved agents based on MRI technique. CD133+ cells were separated by immunomagnetic microbeads selection and grew with serum-free medium. Seven days later, CD133+ cell production was collected and co-incubated with iron complex for 24 h for labeling. The iron-labeled cells were suspended into agarose gel and scanned by MRI for visualization. Labeled cells were also analyzed for cell viability. Iron can be effectively introduced into CD133+ EPCs plasma in culture and visualized by changing the MRI signal intensity. Iron had no influence on cell viability. CONCLUSION: Iron substance can be applied to label CD133+ cells without cytotoxicity and iron-labeled cells can be visualized by MRI image. Due to the non-invasive property and repeatability of MRI technology and this kind of method could be used for tracing in vivo stem cells in the future.     

Hela l-CaD is Implicated in the Migration of Endothelial Cells/Endothelial Progenitor Cells in Human Neoplasms

Caldesmon (CaD) is a major actin-binding protein distributed in a variety of cell types. No functional differences among the isoforms in in vitro studies were found so far. In a previous study we found that the low molecular caldesmon isoform (Hela l-CaD) is expressed in endothelial cells (ECs)/endothelial progenitor cells (EPCs) in tumor vasculature of various human tumors. Activation of cell motility is necessary for the navigation of the tip ECs during angiogenesis, and migration of EPCs from the bone marrow during vasculogenesis. In the present study we searched for features of motility and the intracellular expression sites of Hela l-CaD in ECs/EPCs of various human tumors under histologically preserved microenviroment. We discovered a variety of motility-related cell protrusions like filopodia, microspikes, lamellipodia, podosomes, membrane blebs and membrane ruffles in the activated ECs/EPCs. Hela l-CaD appeared to be invariably expressed in the subregions of these cell protrusions. The findings suggest that Hela l-CaD is implicated in the migration of ECs/EPC in human neoplasms where they contribute to tumor vasculogenesis and angiogenesis.Key words: Hela l-CaD, cell motility, angiogenesis, vasculogenesis, ECs/EPCs     

Hela l-CaD Is Implicated in the Migration of Endothelial Cells/Endothelial Progenitor Cells in Human Neoplasms

Caldesmon (CaD) is a major actin-binding protein distributed in a variety of cell types. No functional differences among the isoforms in in vitro studies were found so far. In a previous study we found that the low molecular caldesmon isoform (Hela l-CaD) is expressed in endothelial cells (ECs)/endothelial progenitor cells (EPCs) in tumor vasculature of various human tumors. Activation of cell motility is necessary for the navigation of the tip ECs during angiogenesis, and migration of EPCs from the bone marrow during vasculogenesis. In the present study we searched for features of motility and the intracellular expression sites of Hela l-CaD in ECs/EPCs of various human tumors under histologically preserved microenviroment. We discovered a variety of motility-related cell protrusions like filopodia, microspikes, lamellipodia, podosomes, membrane blebs and membrane ruffles in the activated ECs/EPCs. Hela l-CaD appeared to be invariably expressed in the subregions of these cell protrusions. The findings suggest that Hela l-CaD is implicated in the migration of ECs/EPC in human neoplasms where they contribute to tumor vasculogenesis and angiogenesis.     

内皮祖细胞分离培养及应用技术新进展

内皮祖细胞(Endothelial progenitor cells,EPCs)是能够增殖、迁移、粘附并分化为血管内皮细胞潜能的一种原始细胞,在修复血管内皮和促进血管生成中具有重要的作用。EPC来源于骨髓,存在于骨髓、外周血、脐带血,新研究表明在脂肪组织、心肌中也能发现EPC的存在。EPC与干细胞的细胞表面标志物相似,功能上亦接近干细胞,但不具有自我更新的功能。近年来EPC已成为热点问题,对疾病诊断,预后判断和靶向治疗方面发挥重要作用,在冠状动脉粥样硬化性疾病、糖尿病血管病变、恶性肿瘤等治疗中全身或局部注射EPC具有更广泛的前景和应用价值。但关于分离培养EPC的方法及细胞表面标志物不完全相同,报道较少,至今尚没有形成统一的标准,本文就对于内皮祖细胞基本现状、分离培养技术、分选鉴定及临床应用方面做一综述。     

血管内皮祖细胞与糖尿病微血管病变研究进展

糖尿病微血管病变严重影响了患者生活质量,是患者致死致残主要原因。微血管病变主要表现在视网膜、肾、神经、心肌组织。微血管病变的机制尚未完全清楚,近年越来越多研究发现血管内皮祖细胞(endothelial progenitor cells,EPCs)是该病发病重要原因。EPCs有分化为成熟的内皮细胞并且参与新血管形成和新生的能力。正常情况下内皮损失和EPCs对内皮的修复作用处于动态平衡状态,一旦EPCs受损,内皮损害和修复之间的平衡被打破,内皮层的完整性遭到破坏,必然参与糖尿病血管病变的发生发展。国内外大量研究证明糖尿病合并大血管病变EPCs数目功能改变,而糖尿病合并微血管病变EPCs的怎样变化?本文就EPCs与糖尿病微血管病变的关系进行系统综述。