脂肪来源间充质干细胞体外定向诱导分化血管细胞的研究进展

脂肪来源的间充质干细胞具有较强的体外增殖能力,因具有生物学特性稳定、来源充足、体外培养条件低等优势已引起各国学者的关注。脂肪间充质干细胞凭借其多向分化潜能,是人体干细胞库潜在的重要来源之一。目前,研究人员已成功地在体外将其诱导为内皮细胞,成骨细胞、成软骨细胞、脂肪前体细胞、平滑肌细胞,心肌细胞、神经样细胞等。就脂肪来源的间充质干细胞体外定向诱导分化血管细胞的研究进展作一综述。     

hESC衍生间充质干细胞可显著促进体外血管生成

人胚胎干细胞(hESC)是具有体外无限增殖能力和多向分化潜能的一类亚全能干细胞,在特定的条件下可被诱导分化为机体的各种细胞包括间充质干细胞(MSC)。该研究以人脂肪间充质干细胞(ADSC)和脐带间充质干细胞(UC-MSC)为对照,对hESC衍生间充质干细胞(hESC-MSC)在体外血管生成中的作用进行了系统的研究,包括其条件培养上清对脐静脉血管内皮细胞(HUVEC)的功能和向血管内皮细胞分化潜能的影响。研究发现,hESC-MSC的条件培养上清可显著促进HUVEC的增殖和迁移,其促进HUVEC增殖的作用显著高于UC-MSC的条件培养上清;hESC-MSC经不同血管内皮细胞诱导方案诱导后均具有体外类血管网络生成的能力,其网络长度均显著高于ADSC和UC-MSC经单一血管内皮细胞诱导方案诱导后的长度。因此,hESC-MSC可显著促进体外血管生成,提示该细胞有望成为一种有效的治疗新型心血管疾病的细胞。     

利用脱细胞血管基质体外构建小口径组织工程血管

目的探讨利用犬的间充质干细胞诱导分化种子细胞,以异种脱细胞血管基质为基础体外构建小口径血管移植物。方法采用密度梯度离心和贴壁培养的方法从犬骨髓中分离出间充质干细胞并体外培养,诱导分化成内皮样细胞和平滑肌样细胞;采用非离子型去垢剂和胰蛋白酶去除猪颈动脉血管壁结构细胞,对脱细胞基质进行组织学、力学检测及孔隙率评估。在生物反应器内采用旋转种植的方法将犬骨髓间充质干细胞诱导的内皮样细胞种植到脱细胞基质上,体外构建小口径组织工程血管。结果犬的骨髓间充质干细胞体外能够定向诱导分化为平滑肌样细胞和内皮样细胞,可以作为血管组织工程的种子细胞。经过脱细胞处理后,光镜和电镜观察证实血管壁的细胞成分完全去除。具有良好的孔径和孔隙率。支架在生物力学、孔隙率等方面符合构建组织工程血管支架的要求。在生物反应器内剪切力条件下可以初步构建出组织工程血管。结论小口径血管移植物可以将间充质干细胞诱导种子细胞,以异种脱细胞血管支架作为基质,在搏动性生物反应器内培养的方法进行构建。     

间充质干细胞源性外泌体microRNA在心脏缺血性损伤修复中的研究进展

心脏缺血性损伤是危害人类健康的重要原因,过去的干细胞疗法具有重要的功能缺陷,如免疫排斥、致瘤性和输注毒性等问题。大量研究表明,间充质干细胞的主要治疗作用是由旁分泌因子所介导。最新研究发现,间充质干细胞来源的外泌体microRNA从移植的干细胞转移至缺血损伤的心脏细胞,调节细胞的增殖、凋亡、炎症和血管生成。本文对来源于间充质干细胞的外泌体及其内部microRNA在心脏缺血性损伤修复中的分子机制进行综述。     

骨髓间质干细胞向心肌细胞分化的可塑性及应用研究进展

减少心肌缺血后损伤,促进心肌细胞和血管再生是治疗心肌缺血损伤、心力衰竭的重要思路,而干细胞移植为该思路带来了新的曙光。骨髓间质干细胞（-mesenchymal stem cells,MSCs）,也称为骨髓基质细胞,能分化为骨、软骨和脂肪细胞表型。研究表明,MSCs还能分化为内皮细胞、神经细胞、平滑肌细胞、骨骼肌细胞和心肌细胞表型。MSCs具有多向分化的潜能,且自体移植可以避免免疫排斥反应,同时也易于在体外大量扩增。研究显示,MSCs移植能抑制损伤心肌的重塑和改善心肌功能。因此,骨髓间质干细胞移植给人们展示了一个诱入的前景。本文综述了近年来有关MSCs特性的新认识,尤其是MSCs向心肌细胞方向分化的可塑性、影响因素和信号转导机制,以及MSCs治疗心肌梗死的动物实验和临床研究进展。     

间充质干细胞特性与应用前景

间充质干细胞是中胚层发育的早期细胞,具备干细胞的基本特性。在发育的不同阶段和特定环境条件下,间充质干细胞可向骨、软骨、肌肉、神经、血管及血液细胞等多种方向分化。在成体的很多器官和组织中也存在着间充质干细胞,以备修复和再生所用。间充质干细胞易于体外培养,扩增迅速,可以分化为多种细胞,为干细胞生物工程提供了一个很好的种子细胞。在明确间充质干细胞生物学特性和分化的机制后,可在体外和体内将其定向诱导分化为多种细胞。间充质干细胞具有巨大的临床应用价值和科学研究价值。     

骨髓间质干细胞修复受损心肌研究进展

骨髓间充质干细胞是一种多潜能干细胞。在体外培养时,多种诱导因素可使其分化为心肌细胞等。目前进行的动物实验和临床研究表明骨髓间充质干细胞具有促进血管增生以及改善心肌梗死后心脏功能的作用,为受损心肌的治疗提供了广阔前景。但是其修复受损心肌的机制仍具有很大争议。本文就以上内容进行综述。     

脐带间充质干细胞牙向分化的可行性研究

再生医学近年来受到越来越多的重视。它开启了治疗由于老化,损伤及一些先天性缺陷所造成的缺损畸形的新途径。其临床应用已涉及到各种组织的修复,包括血液,皮肤,角膜,软骨和骨等。在口腔领域,目前治疗牙缺失主要依靠修复体,种植体和牙移植。然而这些方法都存在一定的缺陷。而通过再生医学的原理和方法实现牙再生治疗可以为机体提供有生命的,有功能的,相容性好的组织结构。种子细胞是牙再生的基础与关键。在牙再生研究中,牙髓间充质干细胞,牙乳头细胞,牙周膜间充质细胞,牙囊细胞及牙源性上皮细胞等牙源性干细胞常通过诱导分化为成釉细胞或成牙本质细胞来作为种子细胞应用,在临床上却难以获取,近来研究也有用骨髓间充质干细胞或脂肪间充质干细胞细胞等非牙源性干细胞者,但其牙向分化能力及分化调控机制还不明确。跻带间充质干细胞在新近的研究中较其它非牙源性干细胞表现出更大的优势,脐带间充质干细胞更原始、具有更高可塑性、更大扩增分化潜能。在此,本文就脐带间充质干细胞向牙细胞系分化的可能性做一论述,并对其可能实现的牙向分化给出可能的方法和策略,为牙再生种子细胞的选取提供新的思路。     

M-CSF诱导人骨髓间充质干细胞分化为肝样细胞的分子机制

本研究主要目的是明确M-CSF诱导骨髓间充质干细胞分化为肝样细胞的分子机制,为临床中的肝移植和治疗肝病提供新思路。对取自于本院骨科治疗的患者的股骨骨髓间充质干细胞进行提取、分离、传代培养及鉴定。流式细胞仪检测BMSCs的表面表型。为了诱导BMSCs的肝分化,本研究将BMSCs加入到培养基中。骨髓间充质干细胞诱导21 d后,BMSCs表达了肝细胞特异性标志物a-蛋白(AFP)和细胞角蛋白18(CK18),通过免疫荧光染色证实了分化与为分化的BMSCs表达的差异性。分化的BMSCs还显示了肝细胞的体外功能特征,包括白蛋白产生、尿素分泌和糖原储存。本研究结果表明,BMSCs在M-CSF诱导下可分化为功能性肝细胞样细胞,可作为肝病治疗的细胞来源。     

间充质干细胞的生物学特性及心血管修复潜能的研究进展

间充质干细胞存在于成体组织中,来源于骨髓、脂肪组织等,在体外易分离和培养,是具有塑料粘附性的一群非均质细胞。它们具有分化的潜能,在适当的条件下可分化为心肌和血管。临床前期研究显示,在心脏损伤模型中移植间充质干细胞有利于心肌修复和心血管形成。其作用机制与间充质干细胞再生和旁分泌能力密切相关。在临床应用中,间充质干细胞具有免疫抑制作用,也可用于异体移植。总之,虽然间充质干细胞的研究尚有许多问题亟待解决,但是它在心脏疾病的细胞治疗和组织工程中已显示出广阔的前景。     

降钙素基因相关肽与动脉粥样硬化

动脉粥样硬化是心血管疾病中最常见的一种血管病变,影响着血管、免疫、代谢等系统。动脉粥样硬化发生发展是一个复杂的过程,它损伤血管内皮,平滑肌等细胞,涉及到多种细胞因子的相互作用。而CGRP具有抑制血管平滑肌增值作用,对预防血管术后再狭窄有重要意义,CGRP能舒张血管,对防治氧化应激引起的内皮损伤具有保护作用,但其机制还不完全清楚。     

降钙素基因相关肽与动脉粥样硬化

动脉粥样硬化是心血管疾病中最常见的一种血管病变,影响着血管、免疫、代谢等系统。动脉粥样硬化发生发展是一个复杂的过程,它损伤血管内皮,平滑肌等细胞,涉及到多种细胞因子的相互作用。而CGRP具有抑制血管平滑肌增值作用,对预防血管术后再狭窄有重要意义,CGRP能舒张血管,对防治氧化应激引起的内皮损伤具有保护作用,但其机制还不完全清楚。     

Direct cell contact influences bone marrow mesenchymal stem cell fate

Adult bone marrow-derived mesenchymal stem cells (MSC) can differentiate into various cell types of mesenchymal origin, but mechanisms regulating such cellular changes are unclear. We have conducted co-culture experiments to examine whether mesenchymal stem cell differentiation is influenced by indirect or direct contact with differentiated cells. Cultured adult mesenchymal stem cells showed some characteristics of synthetic state vascular smooth muscle cells (SMC). When co-cultured with vascular endothelial cells (EC) without cell contact, they exhibited abundant well-organised smooth muscle alpha-actin (alpha-actin) filaments. Direct co-culture with endothelial cells resulted in increased smooth muscle alpha-actin mRNA and protein, yet also comprehensive disruption of smooth muscle alpha-actin filament organisation. In order to assess whether these cell contact effects on mesenchymal stem cells were cell type specific, we also analysed direct co-cultures of mesenchymal stem cells with dermal fibroblasts. However, these experiments were characterised by the appearance of abundant spindle-shaped myofibroblast-like cells containing organised smooth muscle alpha-actin filaments. Thus, direct contact with distinct differentiated cells may be a critical determinant of mesenchymal stem cell fate in blood vessels and other connective tissues.     

Pathophysiology of stem cells in restenosis

Recent evidence has shown that vascular function depends not only on cells within the vessels, but is also significantly modulated by circulating cells derived from the bone marrow. A number of studies indicate that an early reendothelialization by circulating endothelial precursors after vascular injury prevents excessive cell proliferation and restenosis. Conversely, other studies concluded that the homing of other cell fractions, consisting mainly of smooth muscle precursors, cause pathological remodelling. Different cell types have been identified and characterized so far as circulating precursors able to participate in vascular repair by homing and differentiating towards endothelial cells or smooth muscle cells. Among these, endothelial precursor cells, smooth muscle progenitor cells, mesenchymal stem cells and others have been described. The origins, the hierarchy, the role and the markers of these different cell populations are still controversial. Nevertheless, different strategies have been developed so far in animal models to induce the mobilization and the recruitment of stem cells to the injury site, based on physical training, hormone injection and application of stem cell-capturing coated stents. It should also be mentioned that the limited data currently available derived from clinical trials provide contrasting results about the effective role of vascular cell precursors in restenosis prevention, thus indicating that conclusions derived from studies in animal models cannot always be directly applied to humans and that caution should be used in the manipulation of circulating progenitor cells for therapeutic strategies.     

Serotonin-induced endothelial cell proliferation is blocked by omega-3 fatty acids.

Serotonin (5HT) released from aggregating platelets at sites of vascular injury is a known mitogen for vascular endothelial cells. Recent studies have indicated that regenerating endothelial cells at sites of vessel wall injury may play a role in the development of restenosis by synthesizing and releasing growth factors for vascular smooth muscle cells, proliferation of which may result in the development of neointima. Diets rich in fish oils (omega-3 fatty acids) are associated with reduced risk of cardiovascular disease including atherosclerosis and restenosis. This study examined the effect of the omega-3 and other fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on 5HT induced endothelial cell proliferation. Among the fatty acids examined only EPA and DHA could reverse the mitogenic effect of 5HT on vascular endothelial cells, whereas oleic acid or palmitic acid did not have any effect. When added together, EPA and DHA potentiate each other in reversing the mitogenic effect of 5HT. EPA and DHA also inhibited the 5HT-induced increase in the 5HT2 receptor mRNA, without a change in the receptor density or affinity. This data suggests that one of the mechanisms by which omega-3 fatty acids may attenuate the development of atherosclerosis or restenosis is to inhibit the mitogen induced growth of vascular endothelial cells, which attenuates the release of growth factors for vascular smooth muscle cells.     

Biological characteristics of foam cell formation in smooth muscle cells derived from bone marrow stem cells

Bone marrow mesenchymal stem cells (BMSC) can differentiate into diverse cell types, including adipogenic, osteogenic, chondrogenic and myogenic lineages. There are lots of BMSC accumulated in atherosclerosis vessels and differentiate into VSMC. However, it is unclear whether VSMC originated from BMSC (BMSC-SMC) could remodel the vessel in new tunica intima or promote the pathogenesis of atherosclerosis. In this study, BMSC were differentiated into VSMC in response to the transforming growth factor β (TGF-β) and shown to express a number of VSMC markers, such as α-smooth muscle actin (α-SMA) and smooth muscle myosin heavy chain1 (SM-MHC1). BMSC-SMC became foam cells after treatment with 80 mg/L ox-LDL for 72 hours. Ox-LDL could upregulate scavenger receptor class A (SR-A) but downregulate the ATP-binding cassette transporter A1 (ABCA1) and caveolin-1 protein expression, suggesting that modulating relative protein activity contributes to smooth muscle foam cell formation in BMSC-SMC. Furthermore, we found that BMSC-SMC have some biological characteristics that are similar to VSMC, such as the ability of proliferation and secretion of extracellular matrix, but, at the same time, retain some biological characteristics of BMSC, such as a high level of migration. These results suggest that BMSC-SMC could be induced to foam cells and be involved in the development of atherosclerosis.     

Mesenchymal stem cell‐derived exosomes ameliorate erection by reducing oxidative stress damage of corpus cavernosum in a rat model of artery injury

Erectile dysfunction (ED) is a common ageing male's disease, and vascular ED accounts for the largest proportion of all types of ED. One of the mechanisms of vascular ED in the clinic is arterial insufficiency, which mainly caused by atherosclerosis, trauma and surgical. Moreover, oxidative stress damage after tissue ischemia usually aggravated the progress of ED. As a new way of acellular therapy, mesenchymal stem cell‐derived exosomes (MSC‐Exos) have great potential in ED treatment. In the current study, we have explored the mechanism of MSC‐Exos therapy in a rat model of internal iliac artery injury‐induced ED. Compared with intracavernous (IC) injection of phosphate‐buffered saline after artery injury, of note, we observed that both mesenchymal stem cells (MSCs) and MSC‐Exos through IC injection could improve the erectile function to varying degrees. More specifically, IC injection MSC‐Exos could promote cavernous sinus endothelial formation, reduce the organization oxidative stress damage, and improve the nitric oxide synthase and smooth muscle content in the corpus cavernosum. With similar potency compared with the stem cell therapy and other unique advantages, IC injection of MSC‐ Exos could be an effective treatment to ameliorate erectile function in a rat model of arterial injury.     

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。     

BMP4 regulates vascular progenitor development in human embryonic stem cells through a smad‐dependent pathway

The signals that direct pluripotent stem cell differentiation into lineage‐specific cells remain largely unknown. Here, we investigated the roles of BMP on vascular progenitor development from human embryonic stem cells (hESCs). In a serum‐free condition, hESCs sequentially differentiated into CD34+CD31?, CD34+CD31+, and then CD34?CD31+ cells during vascular cell development. CD34+CD31+ cells contained vascular progenitor population that gives rise to endothelial cells and smooth muscle cells. BMP4 promoted hESC differentiation into CD34+CD31+ cells at an early stage. In contrast, TGFβ suppressed BMP4‐induced CD34+CD31+ cell development, and promoted CD34+CD31? cells that failed to give rise to either endothelial or smooth muscle cells. The BMP‐Smad inhibitor, dorsomorphin, inhibited phosphorylation of Smad1/5/8, and blocked hESC differentiation to CD34+CD31+ progenitor cells, suggesting that BMP Smad‐dependent signaling is critical for CD34+CD31+ vascular progenitor development. Our findings provide new insight into how pluripotent hESCs differentiate into vascular cells. J. Cell. Biochem. 109: 363–374, 2010. © 2009 Wiley‐Liss, Inc.     

A new concept of development of neointimal hyperplasia

The intima hyperplasia is a major morphological feature of various arterial pathologies such as atherosclerosis, postangioplasty restenosis and transplantation arteriopathy. It is commonly assumed that smooth muscle cells (SMC) comprising loci of the intima hyperplasia originate from arterial media. However, recent studies suggest that the bone marrow could also supply circulating vascular progenitor of SMCs and endothelial cells (EC). Such bone marrow progenitors participate in the formation of a cellular mass of neointima after experimental allotransplantation, mechanical vessel injury or hyperlipidemia induced experimental atherosclerosis. Circulating SMC and EC progenitors are also likely to be involved in the transplantation arteriopathy development in humans but their roles in the atherosclerosis and restenosis remain to be determined. Stages of the mobilization, defferentiation and proliferation of SMC progenitors could provide point of attack for new therapeutic strategies for the treatment of proliferative vascular diseases. The precise understanding of the neointima cells origin could provide a key for development of the optimal therapeutic strategy of treatnent of such disorders. This review is focused on the pathological significance of circulating progenitors of the bone marrow origin, particularly on the SMC progenitors, for development of vascular wall disorders.