脐带间充质干细胞移植对慢性试验性肝损伤的治疗作用

目的观察脐带间充质干细胞（UC-MSC）对慢性实验性肝损伤的治疗作用并探讨其分子生物学机理。方法 50只7周龄的NOD/SCID小鼠注射四氯化碳（CCL4）制备慢性肝损伤模型后,应用随机数字表的方法随机将实验小鼠随机分成2组：模型组（25只）和UC-MSC移植组（25只）。UC-MSC移植组通过尾静脉注射移植1×106 UC-MSC,模型组注射同样体积的PBS。分别于移植后1、2、3和4周收集肝组织,应用免疫组织化学,RT-PCR和Western blot的方法分析细胞移植前后肝组织的病理生理学特征的变化。采用t检验和方差分析进行统计学分析。结果 UC-MSC移植治疗后肝组织表达人肝细胞特异性AFP,Alb,和内皮细胞特异性CD31,Flk-1。细胞移植4周后v WF标记的血管密度明显增加,同时伴有部分的肝功能改善,谷丙转氨酶（ALT）水平从（55.71±11.33）U/L减至（36.75±12.80）U/L（P〈0.05）。此外,本研究结果表明UC-MSC分泌几种重要的生长因子HGF,FGF-2,VEGF,和VEGF受体通过旁分泌的途径发挥肝组织修复的功能。结论在CCL4诱导的慢性肝损伤模型肝组织,人UC-MSC可以分化成肝细胞样细胞和内皮细胞样细胞,同时旁分泌多种细胞生长因子修复损伤的肝细胞,并伴有肝功能的改善。认为UCMSC移植或许成为将来肝脏损伤疾病一个重要的治疗选择。     

胚胎干细胞分化为肝细胞的研究进展

目前 ,细胞移植作为终末期肝病的辅助治疗方法 ,移植的细胞必须满足在受体肝脏中存活、增殖并可分化为成熟肝细胞两个重要条件 ,但目前应用的肝细胞来源有限 ,其功能随着培养时间的延长而逐渐下降等问题限制了这一治疗策略的广泛开展。作为具有发育全能性和无限增殖能力的细胞 ,胚胎干细胞向肝细胞的分化研究近年来引起了广泛的关注 ,并取得了较大的进展 ,寻找合适、高效的分化诱导方法是目前研究的热点之一。胚胎干细胞向肝细胞的分化研究既可以为临床细胞替代治疗提供合适的细胞来源 ,也可以在药物评估和肝脏发育分化基础研究方面起到重要的作用。通过概括肝脏和拟胚体分化发育的分子机制 ,对体外胚胎干细胞向肝细胞分化的几种诱导体系作了介绍 ,并对分化肝细胞的应用前景和存在的问题进行了讨论。     

成体干细胞向肝细胞分化

成体干细胞跨越胚层限制分化为其他胚层来源的细胞,对揭示不同胚层细胞间相互分化的生物学意义和机制具有重要学术价值,并可以为临床细胞移植治疗开辟新的途径,从而成为当前研究的热点之一。综述了近年来肝源性卵圆细胞、成肝细胞、骨髓源干细胞和其他成体干细胞跨越分化为肝细胞的研究现状与进展,以及卵圆细胞、成肝细胞等的分离鉴定,表面标志、生物学特征和跨越分化机制,并对成体干细胞在肝脏疾病细胞治疗上的应用前景作了展望。     

肝细胞永生化的研究与应用

正常体外培养的细胞在体外有一定的寿命,一般传代不超过50代,被称为有限细胞系,但有些体外培养的细胞可经过自发或外界因素的影响从凋亡危机中逃离出来,从而形成具有无限增殖能力的细胞系,成为永生化细胞系.由于肝细胞在体外增殖能力极弱,培养困难,其应用受到较大限制,而肝细胞经永生化后具有了无限增殖优势,使其在肝细胞移植,生物人工肝以及药理、毒理学等研究方面有广阔的应用前景.就近年来肝细胞永生化方法及其应用作简要的综述.     

肝细胞永生化策略研究进展

正常体细胞在细胞分裂过程中由于无法维持端粒的长度和染色体的稳定而衰老、死亡。建立基因稳定、无致瘤性的永生化细胞是永生化研究的目的所在。利用Cre-loxP系统构建的可恢复性永生化细胞可用于以细胞为基础的临床治疗。分化良好并具有肝脏正常合成代谢功能的永生化肝细胞在生物医学研究,尤其是在肝细胞移植、生物人工肝支持治疗以及药理学和毒理学研究方面具有广泛的应用前景。     

《细胞-干细胞》:科学家发现获取肝细胞新方法

<正>中国科学院上海生物化学与细胞生物学研究所惠利健研究组在最新的一项研究中发现,通过表达三个肝脏转录因子,可成功将人体皮肤细胞转变为肝细胞。这项获得人类肝细胞的方法,向最终实现肝细胞治疗、生物人工肝等领域前进了一大步。2月28日,《细胞-干细胞》在线发表了该成果。中国被称为"肝炎大国"。但肝脏供体的缺乏严重阻碍了肝脏移植治疗的应用。近年来新发展起来的肝细胞移植、生物人工肝等新型治疗手段也依然面临着肝细胞缺乏的问题。     

诱导多能干细胞技术的优化及其应用前景

诱导多能干细胞(induced pluripotent stem cells, iPSCs)是类似胚胎干细胞的一种细胞类型,可以通过对已分化的体细胞进行诱导重编程获得,具有自我更新能力和多潜能性,在体外疾病模型的建立、移植替代治疗、发育学等方面有广阔的应用前景,但致瘤性、转化率低、疾病模型拟合度差等缺点限制着iPS技术在临床和科研上的推广。对近几年诱导多能干细胞技术优化方面取得的新进展进行综述,重点阐述降低致瘤性和提高转化率的几种方法及iPS在临床和科研上的应用前景。     

靶向GPC3的第四代嵌合抗原受体T细胞 (分泌IL-7和CCL19) 的构建以及功能

基于嵌合抗原受体修饰的T细胞(CAR-T)的过继免疫疗法已被证明是治疗恶性肿瘤最有希望的策略之一,但是目前其在实体瘤中的应用依然有限。研究表明磷脂酰肌醇蛋白聚糖3 (GPC3)对肝细胞癌来说是一种有意义的诊断、治疗和预后生物标志物,且已有利用第二代/第三代GPC3靶向的CAR-T细胞治疗肝细胞癌的研究报道。为了进一步提高治疗效果,构建同时表达GPC3 CAR、人源IL-7和CCL19细胞因子的第四代慢病毒载体,转染293T细胞包装慢病毒并感染人T淋巴细胞制备靶向GPC3的第四代CAR-T细胞(GPC3-BBZ-7×19)。利用细胞计数、趋化小室、荧光素酶生物发光法以及流式细胞术等比较其与第二代GPC3 CAR-T细胞(GPC3-BBZ)在增殖、迁移、杀伤以及亚型分布方面的区别,评估GPC3-BBZ-7×19 CAR-T细胞对免疫缺陷小鼠体内GPC3阳性的肝细胞癌腹腔移植瘤生长的作用。结果表明与GPC3-BBZ CAR-T细胞相比,GPC3-BBZ-7×19 CAR-T细胞具备更强的增殖能力、趋化能力以及记忆干细胞(Stem memory T cell,Tscm)组成比(P值均0.05),而在体外特异性杀伤GPC3阳性的肝细胞癌细胞以及细胞因子分泌水平方面无显著差异。此外,GPC3-BBZ-7×19 CAR-T细胞能够明显抑制免疫缺陷小鼠体内的GPC3阳性肝细胞癌移植瘤模型。因此靶向GPC3的第四代CAR-T细胞(分泌IL-7和CCL19)有望比第二代GPC3靶向的CAR-T细胞更持久有效地对抗肿瘤,并产生针对肿瘤的记忆功能,为以后的临床试验提供了临床前研究基础。     

前列腺癌细胞结合单链抗体的克隆表达及其功能初步研究

目的:在获得纯化的前列腺癌细胞结合单链抗体scFvP-9后,对其生物学功能进行初步探讨,为前列腺癌的诊断和治疗奠定基础。方法:利用MTT比色实验初步研究了scFvP-9对多种肿瘤细胞及正常肝细胞HL02的生物学作用,并建立人宫颈癌的裸鼠模型,进行了抑瘤实验。结果:scFvP-9不影响HL02细胞及恶性程度低的人前列腺癌细胞LNCaP的生长,但对人前列腺癌细胞PC3、人宫颈癌细胞HeLa、人肺癌细胞PLA801D均有生长抑制作用;scFvP-9在荷瘤模型体内也显示了较好的抑瘤效果,与对照组相比有显著性差别,且瘤周皮下给药组效果更为显著。结论:该抗体具有潜在的重要临床应用价值。     

动物模型在间充质干细胞治疗慢性肝病临床前研究的应用

慢性肝病进一步发展为肝纤维化并导致肝硬化,此时除了器官移植外没有更为有效的治疗方法。然而器官缺乏的问题迫使人们寻找更为有效的治疗策略。间充质干细胞(mesenchymal stem cells,MSCs)有着免疫调节、分化成肝细胞、促进原位肝细胞再生和抑制肝星状细胞的激活等能力,所以利用MSCs开展细胞移植治疗具有非常广阔的前景。本文通过综述各类人的肝病动物模型和运用这些动物模型开展MSCs细胞移植治疗肝病的临床前研究的进展和意义,将为今后在MSCs开展临床治疗的广泛应用中提供安全性和有效性评价的科学依据。     

Therapeutic potential of hepatocyte transplantation

Liver repopulation with transplanted cells offers unique opportunities for treating a variety of diseases and for studies of fundamental mechanisms in cell biology. Our understanding of the basis of liver repopulation has come from studies of transplanted cells in animal models. A variety of studies established that transplanted hepatocytes as well as stem/progenitor cells survive, engraft, and function in the liver. Transplanted cells survive life-long, although cells do not proliferate in the normal liver. On the other hand, the liver is repopulated extensively when diseases or other injuries afflict native hepatocytes but spare transplanted cells. The identification of ways to repopulate the liver with transplanted cells has greatly reinvigorated the field of liver cell therapy. The confluence of insights in stem/progenitor cells, transplantation immunology, cryobiology, and liver repopulation in specific models of human diseases indicates that the field of liver cell therapy will begin to reap the promised fruit in the near future.     

Generation of hybrid hepatocytes by cell fusion from monkey embryoid body cells in the injured mouse liver

Monkey embryonic stem (ES) cells have characteristics that are similar to human ES cells, and might be useful as a substitute model for preclinical research. When embryoid bodies (EBs) formed from monkey ES cells were cultured, expression of many hepatocyte-related genes including cytochrome P450 (Cyp) 3a and Cyp7a1 was observed. Hepatocytes were immunocytochemically observed using antibodies against albumin (ALB), cytokeratin-8/18, and α1-antitrypsin in the developing EBs. The in vitro differentiation potential of monkey ES cells into the hepatic lineage prompted us to examine the transplantability of monkey EB cells. As an initial approach to assess the repopulation potential, we transplanted EB cells into immunodeficient urokinase-type plasminogen activator transgenic mice that undergo liver failure. After transplantation, the hepatocyte colonies expressing monkey ALB were observed in the mouse liver. Fluorescence in-situ hybridization revealed that the repopulating hepatocytes arise from cell fusion between transplanted monkey EB cells and recipient mouse hepatocytes. In contrast, neither cell fusion nor repopulation of hepatocytes was observed in the recipient liver after undifferentiated ES cell transplantation. These results indicate that the differentiated cells in developing monkey EBs, but not contaminating ES cells, generate functional hepatocytes by cell fusion with recipient mouse hepatocytes, and repopulate injured mouse liver.     

In Situ Transplantation of Alginate Bioencapsulated Adipose Tissues Derived Stem Cells (ADSCs) via Hepatic Injection in a Mouse Model

Objective

Adipose tissue derived stem cells (ADSCs) transplantation has recently gained widespread enthusiasm, particularly in the perspective to use them as potential alternative cell sources for hepatocytes in cell based therapy, mainly because of their capability of hepatogenic differentiation in vitro and in vivo. But some challenges remain to be addressed, including whether ADSCs can be provided effectively to the target organ and whether subsequent proliferation of transplanted cells can be achieved. To date, intrasplenic injection is the conventional method to deliver ADSCs into the liver; however, a number of donor cells retained in the spleen has been reported. In this study, our objective is to evaluate a novel route to transplant ADSCs specifically to the liver. We aimed to test the feasibility of in situ transplantation of ADSCs by injecting bioencapsulated ADSCs into the liver in mouse model.

Methods

The ADSCs isolated from human alpha 1 antitrypsin (M-hAAT) transgenic mice were used to allow delivered ADSCs be readily identified in the liver of recipient mice, and alginate was selected as a cell carrier. We first evaluated whether alginate microspheres are implantable into the liver tissue by injection and whether ADSCs could migrate from alginate microspheres (study one). Once proven, we then examined the in vivo fate of ADSCs loaded microspheres in the liver. Specifically, we evaluated whether transplanted, undifferentiated ASDCs could be induced by the local microenvironment toward hepatogenic differentiation and the distribution of surviving ADSCs in major tissue organs (study two).

Results

Our results indicated ADSCs loaded alginate microspheres were implantable into the liver. Both degraded and residual alginate microspheres were observed in the liver up to three weeks. The viable ADSCs were detectable surrounding degraded and residual alginate microspheres in the liver and other major organs such as bone marrow and the lungs. Importantly, transplanted ADSCs underwent hepatogenic differentiation to become cells expressing albumin in the liver. These findings improve our understanding of the interplay between ADSCs (donor cells), alginate (biomaterial), and local microenvironment in a hepatectomized mouse model, and might improve the strategy of in situ transplantation of ADSCs in treating liver diseases.     

Delineating the Hepatocyte's Hematopoietic Fusion Partner

Cell fusion has evolved as an explanation of how transplanted bone marrow cells adopt the phenotype of hepatocytes, Purkinje neurons, skeletal and cardiac muscle cells. In vivo nuclear transfer associated with cell fusion has direct implications for regenerative medicine, but the spontaneous frequency of cell fusion is well below the threshold of therapeutic significance. Increased efficiency could be achieved by utilizing cellular factors known to govern fusion but for this the identity of the hematopoietic cell that fuses with the host cell must be known. Using increasingly lineage-restricted donor bone marrow cell populations we have shown in mouse liver that fusion occurs between host hepatocytes and transplanted myelomonocytic cells such as macrophages. Now it should be feasible to increase the efficiency and assess the potential of cell fusion for the correction of a broad range of somatic cell types that can be targeted by fusion.     

Potential treatment of liver-related disorders with in vitro expanded human liver precursors

Abstract Inherited deficiencies in critical components of metabolic pathways are the primary cause of many liver and lysosomal disorders, most of which are incurable. Stem cell transplantation may offer a new type of treatment for these diseases. We have isolated hepatocyte precursors from human fetal livers. These cells were highly proliferative in vitro in media with or without serum. Expanded hepatocyte precursors expressed endoderm and early hepatocyte markers. The precursors synthesized a large number of molecules related to human metabolic diseases and released some of them into the environment. In a homing test, these cells migrated preferentially into the liver. When transplanted into fetal sheep liver, they incorporated into the liver tissue and differentiated into hepatocytes. Transplantation of the liver precursors to α- l -iduronidase-deficient mice partially corrected the enzyme deficiency. Data from these studies suggest that in vitro expanded human liver precursor cells are a potential cell source for the treatment of liver- and lysosome-related disorders.     

Potential of bioengineering processes for therapeutic repopulation of the liver with cells

Multiple unique aspects of liver biology make this organ an excellent paradigm for novel cell and gene therapy applications. In recent years, insights were obtained into how transplanted cells engraft and proliferate in the liver, including in the context of pre-existing disease. Also, a variety of animal models were studied to establish the basis of cell and gene therapy applications in specific disorders. Through ongoing research activity, additional mechanisms in liver repopulation have been uncovered, where manipulation of specific cell compartments and cellular processes,e.g., those aimed at extracellular matrix component receptors or soluble signals in transplanted and native cells can be exploited for enhancing cell engraftment and proliferation. Such studies demonstrate the possibility of applying biotechnology and/or bioengineering principles to organ replacement aimed at cell and gene therapy. Joining of these disciplines with research in stem cell biology, particularly in efforts concerning targeting of transplanted stem cells to given organs with achievement of lineage-specific cell differentiation and function, will be particularly important for future cell and gene therapy applications. This review offers an overview of relevant mechanisms in liver repopulation.     

人鼠肝组织嵌合体模型的制备

目的研究制备人鼠肝组织嵌合小鼠模型。方法将人骨髓干细胞直接注射到一定日龄胎鼠肝组织,每只注射移植约1×109人骨髓干细胞。用免疫组化对出生一定日龄移植小鼠肝脏进行甲胎蛋白免疫组织化学检测,检定分析人肝细胞在小鼠体内嵌合生长情况。结果移植人骨髓干细胞胎鼠出生2月龄、12月龄可检测到甲胎蛋白。结论将人骨髓干细胞移植小鼠肝脏内能够存活并分化成人肝细胞并能够长期存活。     

成体心脏干细胞经静脉移植后在心梗小鼠体内的分布研究

目的：观察心肌梗死小鼠静脉移植成体心脏干细胞后,细胞在小鼠体内各器官的分布情况。明确心梗后静脉移植成体心脏干 细胞在小鼠体内的分布和归巢情况。方法：分离培养小鼠心脏成体干细胞,采用流式细胞仪鉴定细胞,通过亲脂性染料CM-DiI标 记细胞后行小鼠急性心肌梗死模型建立和细胞移植,分别在细胞移植后7、14、8 天取小鼠心脏、肝脏、脑、脊髓、肺脏,行冰冻切 片,在荧光显微镜下观察移植细胞在各组织器官存活和分布情况。结果：成体心脏干细胞分离培养后呈贴壁生长,流式细胞仪检 测显示细胞纯度>80%。CM-DiI标记后荧光显微镜下观察可见标记的细胞胞浆胞核均被染成呈明亮的红色。心肌梗死后经静脉 移植成体心脏干细胞,细胞在各组织中分布呈变化过程,7 天时,在肺脏和肝脏分布较多,至14 天和28 天时,肺脏和肝脏分布减 少,心脏分布逐渐增多,表现出向心脏的" 归巢" 现象,而脑和脊髓在28 天的观察时间内分布较少。结论：采用CM-DiI标记心 脏成体干细胞,操作简单,标记效果好,可用于短期的细胞体内追踪。小鼠心肌梗死后行经静脉成体心脏干细胞移植,28 天后细胞 在心脏的分布逐渐增多,表现出向心脏的" 归巢" 现象。     

Fibrogenic Potential of Human Multipotent Mesenchymal Stromal Cells in Injured Liver

Multipotent mesenchymal stromal cells (MSC) are currently investigated clinically as cellular therapy for a variety of diseases. Differentiation of MSC toward endodermal lineages, including hepatocytes and their therapeutic effect on fibrosis has been described but remains controversial. Recent evidence attributed a fibrotic potential to MSC. As differentiation potential might be dependent of donor age, we studied MSC derived from adult and pediatric human bone marrow and their potential to differentiate into hepatocytes or myofibroblasts in vitro and in vivo. Following characterization, expanded adult and pediatric MSC were co-cultured with a human hepatoma cell line, Huh-7, in a hepatogenic differentiation medium containing Hepatocyte growth factor, Fibroblast growth factor 4 and oncostatin M. In vivo, MSC were transplanted into spleen or liver of NOD/SCID mice undergoing partial hepatectomy and retrorsine treatment. Expression of mesenchymal and hepatic markers was analyzed by RT-PCR, Western blot and immunohistochemistry. In vitro, adult and pediatric MSC expressed characteristic surface antigens of MSC. Expansion capacity of pediatric MSC was significantly higher when compared to adult MSC. In co-culture with Huh-7 cells in hepatogenic differentiation medium, albumin expression was more frequently detected in pediatric MSC (5/8 experiments) when compared to adult MSC (2/10 experiments). However, in such condition pediatric MSC expressed alpha smooth muscle more strongly than adult MSC. Stable engraftment in the liver was not achieved after intrasplenic injection of pediatric or adult MSC. After intrahepatic injection, MSC permanently remained in liver tissue, kept a mesenchymal morphology and expressed vimentin and alpha smooth muscle actin, but no hepatic markers. Further, MSC localization merges with collagen deposition in transplanted liver and no difference was observed using adult or pediatric MSC. In conclusion, when transplanted into an injured or regenerating liver, MSC differentiated into myofibroblasts with development of fibrous tissue, regardless of donor age. These results indicate that MSC in certain circumstances might be harmful due to their fibrogenic potential and this should be considered before potential use of MSC for cell therapy.     

Mesenchymal stem cells showed the highest potential for the regeneration of injured liver tissue compared with other subpopulations of the bone marrow

We have previously reported that bone marrow cells (BMCs) participate in the regeneration after liver injury. However, it is not established that this is the result of differentiation of hematopoietic stem cells (HSCs), mesenchymal stem cells (MSCs) or the combination of both. We investigated the contribution of each cell fraction to the regenerative process. First, we confirmed that transplanted stem cells migrate directly to injured liver tissue without dispersing to other organs. Next, we divided green fluorescent protein (GFP)-expressing BMCs into three populations as mononuclear cells, MSCs and HSCs. We then compared the engraftment capacity after transplantation of each fraction of cells into liver-injured mice. Of these, the MSCs transplanted group showed the highest GFP fluorescence intensities in liver tissue by flow cytometry analysis and confocal microscopic observation. Furthermore, MSCs showed differentiation potential into hepatocytes when co-cultured with injured liver cells, which suggests that MSCs showed highest potential for the regeneration of injured liver tissue compared with those of the other two cell refractions.