干细胞对肝脏疾病的治疗现状及前景

一、国内外干细胞研究与应用现状干细胞生物学兴起为包括终末期肝病在内的多种难治性人类疾病治疗带来新的希望。干细胞具有高度的自我更新及多向分化潜能。自我更新特性使得干细胞可以成为一个源源不竭的细胞库,克服了肝细胞增殖能力有限的问题;多向分化潜能赋予干细胞一定的可塑性,分化为具有功能的肝细胞。在体外,将干细胞诱导分化为肝细胞,可以解决生物人工肝种子细胞来源困难的问题。在体内,将干细胞经肝动静脉回输入肝脏,从一定程度上提高终末     

干细胞向甲状旁腺细胞的分化及在甲状旁腺功能减退中的研究进展

干细胞是一类能够自我复制、自我更新,具有多向分化潜能,能产生多种分化细胞类型的细胞,由于它的自我复制和多向分化潜能,干细胞技术已经被广泛的应用于细胞移植治疗中。甲状旁腺功能减退作为一种内分泌疾病,目前的治疗方案都不能从根本上治疗该疾病。因此应用干细胞来源的甲状旁腺细胞移植治疗甲状旁腺功能减退越来越受到医学界的重视。目前,已有科研团队报道了应用胚胎干细胞（ESCs）、胸腺上皮细胞和扁桃体间充质细胞向甲状旁腺细胞分化及其在甲状旁腺功能减退中的治疗。本文将干细胞向甲状旁腺细胞的分化及在甲状旁腺功能减退治疗中的研究进展进行综述。     

胚胎干细胞体外诱导分化

胚胎干细胞能在体外长期不断自我更新,具有高度分化潜能,可分化成胎儿和成体的几乎所有类型的细胞,如心肌细胞、神经细胞、上皮细胞、肝细胞、血细胞、胰岛细胞、脂肪细胞及生殖细胞等.在细胞治疗和组织器官替代治疗、发育生物学等的研究中将具有广阔的应用前景.目前已有多种胚胎干细胞体外定向诱导的报道.本文从体外诱导分化影响因素和几种主要诱导细胞类型进行分析和总结,为胚胎干细胞的诱导分化研究提供参考资料.     

间充质干细胞对免疫细胞的抑制作用及其机制

间充质干细胞是一群来源于发育早期中胚层的具有自我更新和多向分化潜能的干细胞,具有分化为脂肪细胞、肝细胞、成骨细胞、软骨细胞、神经细胞等多种细胞的能力.近年来的相关研究表明,间充质干细胞具有低免疫原性,它可以通过抑制淋巴细胞的增殖、抑制抗原呈递细胞分化成熟及功能发挥、抑制细胞毒性T淋巴细胞的形成、增加调节性T细胞比例等多种途径发挥免疫调节作用,从而成为移植领域、各种退行性和衰竭性疑难病症的替代治疗的研究热点.本文就间充质干细胞对免疫细胞的抑制作用及其机制的研究进展进行综述.     

骨髓间充质干细胞的多向分化潜能研究进展

骨髓间充质干细胞(bone marrow stromal stem cell,BMSSC)是成体干细胞中最受关注的细胞之一,它不仅在造血和免疫细胞发生发育中发挥重要作用,而且参与多种器官组织的再生和损伤修复,特别是近年来发现BMSSC具有向不同胚层来源细胞跨越分化(trans-differentiation)的可塑性,不仅有可能揭示细胞分化的新机制,而且为众多疾病的临床治疗提供了新思路。目前已揭示,BMSSC除了具有向成骨、软骨和脂肪细胞分化潜能外,还有向肝细胞、神经细胞、心肌细胞、血管内皮细胞和胰岛细胞等多向分化的潜能,本文就当前BMSSC的多向分化潜能研究进展作一综述。     

诱导多功能干细胞(iPSC)技术的研究进展

诱导多功能干细胞(iPSC)是采用基因重排的方法,使已分化的成体细胞重新获得多向分化潜能的细胞.由于它具有多种组织分化的特性,不存在伦理方面的争议,成为再生医学领域的研究热点.小鼠、人的多种分化的成体细胞已被成功诱导为具有多向分化潜能的多功能干细胞.诱导分化技术不断得到验证与改进,正在逐步得到推广,为iPS细胞向临床应用打下了坚实的基础.     

胚胎干细胞体外诱导分化

胚胎干细胞能在体外长期不断自我更新,具有高度分化潜能,可分化成胎儿和成体的几乎所有类型的细胞,如心肌细胞、神经细胞、上皮细胞、肝细胞、血细胞、胰岛细胞、脂肪细胞及生殖细胞等。在细胞治疗和组织器官替代治疗、发育生物学等的研究中将具有广阔的应用前景。目前已有多种胚胎干细胞体外定向诱导的报道。本文从体外诱导分化影响因素和几种主要诱导细胞类型进行分析和总结,为胚胎干细胞的诱导分化研究提供参考资料。     

原始生殖细胞体外培养及应用研究

原始生殖细胞是来源于胚胎生殖嵴的一类具有多向分化潜能的干细胞,其形态、细胞表面标志、分化潜能均与来源于囊胚内细胞团的干细胞相似.在饲养细胞层和多种生长因子的共同作用下,可保持原生殖细胞在体外不断增殖而不分化,最终建立EG细胞系.本文就原始生殖细胞体外培养,建立EG细胞系及其应用前景作一综述.     

脂肪组织源性干细胞研究进展

增加具有完整功能的种子细胞数目是细胞移植的首要环节。近来研究发现,成体动物脂肪组织中含有大量的具有多向分化潜能的间充质干细胞,在特定条件下可分化为多种组织细胞,如脂肪细胞、成骨细胞、软骨细胞、肌细胞及神经星状细胞等,且具有极强的自我复制能力,有望成为组织工程理想的种子细胞。本文综述了脂肪组织源性干细胞（ADSCs）的发现、生物学特性、多向分化潜能、应用前景及存在的问题。     

间充质干细胞的分化与能量代谢

间充质干细胞(mesenchymal stem cells, MSCs)是一种具有自我更新及多向分化潜能的多能干细胞。MSCs的多向分化潜能、旁分泌和免疫调控功能在损伤组织修复、再生和细胞治疗方面显示出巨大的临床应用前景。能量代谢是细胞新陈代谢的重要内容和细胞功能实现的重要基础,能量代谢的变化与细胞多种生物学行为的改变密切相关。干细胞分化过程中能量代谢发生了改变,而改变干细胞的能量代谢途径也能调控干细胞的分化命运,因此干细胞与能量代谢之间相互影响。现就MSCs的分化与能量代谢之间的关系进行综述。     

Liver engraftment potential of hepatic cells derived from patient-specific induced pluripotent stem cells

Human induced pluripotent stem cells (iPSCs) are potential renewable sources of hepatocytes for drug development and cell therapy. Differentiation of human iPSCs into different developmental stages of hepatic cells has been achieved and improved during the last several years. We have recently demonstrated the liver engraftment and regenerative capabilities of human iPSC-derived multistage hepatic cells in vivo. Here we describe the in vitro and in vivo activities of hepatic cells derived from patientspecific iPSCs, including multiple lines established from either inherited or acquired liver diseases, and discuss basic and clinical applications of these cells for disease modeling, drug screening and discovery, gene therapy and cell replacement therapy.Key words: induced pluripotent stem cells (iPSCs), hepatic differentiation, liver ngraftment, disease modeling, drug testing, alpha-1 antitrypsin, liver cirrhosis, hepatocellular carcinoma, cell therapy     

Differentiation of liver epithelial (stem-like) cells into hepatocytes induced by coculture with hepatic stellate cells

The liver is believed to contain stem cells that can differentiate into either hepatocytes or biliary epithelial cells. In the present study, we established a nonhepatocytic epithelial cell line from the normal livers of adult rats. The established cells, designated HSL cells, were immunoreactive against alpha-fetoprotein, but neither albumin nor cytokeratin 19. To demonstrate the differentiation potential of HSL cells in vitro, the cells were cocultured with hepatic stellate cells as a mixture or separately using insert wells. Consequently, although coculture with hepatic stellate cells rendered HSL cells able to produce albumin, the mixed coculture system mimicking the hepatic environment elicited this phenomenon more effectively than the separated coculture system. In conclusion, HSL cells have immature properties and the potential to differentiate into mature cells. Not only the extracellular matrices but also soluble factors, which are produced by hepatic stellate cells, induce this maturation, demonstrating the importance of the hepatic environment for hepatocyte differentiation.     

Nuclear translocation of β-catenin during mesenchymal stem cells differentiation into hepatocytes is associated with a tumoral phenotype

Wnt/β-catenin pathway controls biochemical processes related to cell differentiation. In committed cells the alteration of this pathway has been associated with tumors as hepatocellular carcinoma or hepatoblastoma. The present study evaluated the role of Wnt/β-catenin activation during human mesenchymal stem cells differentiation into hepatocytes. The differentiation to hepatocytes was achieved by the addition of two different conditioned media. In one of them, β-catenin nuclear translocation, up-regulation of genes related to the Wnt/β-catenin pathway, such as Lrp5 and Fzd3, as well as the oncogenes c-myc and p53 were observed. While in the other protocol there was a Wnt/β-catenin inactivation. Hepatocytes with nuclear translocation of β-catenin also had abnormal cellular proliferation, and expressed membrane proteins involved in hepatocellular carcinoma, metastatic behavior and cancer stem cells. Further, these cells had also increased auto-renewal capability as shown in spheroids formation assay. Comparison of both differentiation protocols by 2D-DIGE proteomic analysis revealed differential expression of 11 proteins with altered expression in hepatocellular carcinoma. Cathepsin B and D, adenine phosphoribosyltransferase, triosephosphate isomerase, inorganic pyrophosphatase, peptidyl-prolyl cis-trans isomerase A or lactate dehydrogenase β-chain were up-regulated only with the protocol associated with Wnt signaling activation while other proteins involved in tumor suppression, such as transgelin or tropomyosin β-chain were down-regulated in this protocol. In conclusion, our results suggest that activation of the Wnt/β-catenin pathway during human mesenchymal stem cells differentiation into hepatocytes is associated with a tumoral phenotype.     

Hepatic oval 'stem' cell in liver regeneration

Hepatic oval cell activation, proliferation, and differentiation has been observed under certain physiological conditions, mainly when the proliferation of existing hepatocytes has been inhibited followed by severe hepatic injury. Hepatic oval cells display a distinct phenotype and have been shown to be a bipotential progenitor of two types of epithelial cells found in the liver, hepatocytes and bile ductular cells. Bone marrow stem cells have recently been shown to be a potential source of the hepatic oval cells and that reconstitution of an injured liver from a purified stem cell population is possible. The focus of this review is on the studies involving the activation, proliferation, and differentiation of these hepatic oval cells and the role that they play in regeneration of the damaged liver. In order to present the potentiality of the hepatic oval cell, an experimental model that involves the inhibition of normal hepatic growth and division as well as severe hepatic injury via chemical or surgical means has been employed. In this model, an as yet undetermined signal or perhaps the lack of regenerative capability in the hepatocytes activates the hepatic oval cell compartment. However, other than understanding a potential origin of these cells and some of the markers that characterize them, it still remains unclear as to how these cells migrate ('home') into the damaged areas and how they begin their differentiation into mature and functioning hepatic cells.     

Generation,characterization and potential therapeutic applications of mature and functional hepatocytes from stem cells

Liver cancer is the sixth most common tumor in the world and the majority of patients with this disease usually die within 1 year. The effective treatment for end‐stage liver disease (also known as liver failure), including liver cancer or cirrhosis, is liver transplantation. However, there is a severe shortage of liver donors worldwide, which is the major handicap for the treatment of patients with liver failure. Scarcity of liver donors underscores the urgent need of using stem cell therapy to the end‐stage liver disease. Notably, hepatocytes have recently been generated from hepatic and extra‐hepatic stem cells. We have obtained mature and functional hepatocytes from rat hepatic stem cells. Here, we review the advancements on hepatic differentiation from various stem cells, including hepatic stem cells, embryonic stem cells, the induced pluripotent stem cells, hematopoietic stem cells, mesenchymal stem cells, and probably spermatogonial stem cells. The advantages, disadvantages, and concerns on differentiation of these stem cells into hepatic cells are highlighted. We further address the methodologies, phenotypes, and functional characterization on the differentiation of numerous stem cells into hepatic cells. Differentiation of stem cells into mature and functional hepatocytes, especially from an extra‐hepatic stem cell source, would circumvent the scarcity of liver donors and human hepatocytes, and most importantly it would offer an ideal and promising source of hepatocytes for cell therapy and tissue engineering in treating liver disease. J. Cell. Physiol. 228: 298–305, 2013. © 2012 Wiley Periodicals, Inc.