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 patient specific 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.     

Hematopoietic cells as sources for patient-specific iPSCs and disease modeling

In addition to being an attractive source for cell replacement therapy, human induced pluripotent stem cells (iPSCs) also have great potential for disease modeling and drug development. During the recent several years, cell reprogramming technologies have evolved to generate virus-free and integration-free human iPSCs from easily accessible sources such as patient skin fibroblasts and peripheral blood samples. Hematopoietic cells from umbilical cord blood banks and Epstein Barr virus (EBV) immortalized B lymphocyte repositories represent alternative sources for human genetic materials of diverse backgrounds. Ability to reprogram these banked blood cells to pluripotency and differentiate them into a variety of specialized and functional cell types provides valuable tools for studying underlying mechanisms of a broad range of diseases including rare inherited disorders. Here we describe the recent advances in generating disease specific human iPSCs from these different types of hematopoietic cells and their potential applications in disease modeling and regenerative medicine.Key words: induced pluripotent stem cells (iPSCs), blood, B lymphocytes, hematopoietic differentiation, hepatic differentiation, disease modeling, drug testing     

Applications of patient-specific induced pluripotent stem cells; focused on disease modeling, drug screening and therapeutic potentials for liver disease

The recent advances in the induced pluripotent stem cell (iPSC) research have significantly changed our perspectives on regenerative medicine by providing researchers with a unique tool to derive disease-specific stem cells for study. In this review, we describe the human iPSC generation from developmentally diverse origins (i.e. endoderm-, mesoderm-, and ectoderm- tissue derived human iPSCs) and multistage hepatic differentiation protocols, and discuss both basic and clinical applications of these cells including disease modeling, drug toxicity screening/drug discovery, gene therapy and cell replacement therapy.     

Hematopoietic cells as sources for patient-specific iPSCs and disease modeling

In addition to being an attractive source for cell replacement therapy, human induced pluripotent stem cells (iPSCs) also have great potential for disease modeling and drug development. During the recent several years, cell reprogramming technologies have evolved to generate virus-free and integration-free human iPSCs from easily accessible sources such as patient skin fibroblasts and peripheral blood samples. Hematopoietic cells from umbilical cord blood banks and Epstein Barr virus (EBV) immortalized B lymphocyte repositories represent alternative sources for human genetic materials of diverse backgrounds. Ability to reprogram these banked blood cells to pluripotency and differentiate them into a variety of specialized and functional cell types provides valuable tools for studying underlying mechanisms of a broad range of diseases including rare inherited disorders. Here we describe the recent advances in generating disease specific human iPSCs from these different types of hematopoietic cells and their potential applications in disease modeling and regenerative medicine.     

Highly efficient derivation of ventricular cardiomyocytes from induced pluripotent stem cells with a distinct epigenetic signature

Cardiomyocytes derived from pluripotent stem cells can be applied in drug testing, disease modeling and cell-based therapy. However, without procardiogenic growth factors, the efficiency of cardiomyogenesis from pluripotent stem cells is usually low and the resulting cardiomyocyte population is heterogeneous. Here, we demonstrate that induced pluripotent stem cells (iPSCs) can be derived from murine ventricular myocytes (VMs), and consistent with other reports of iPSCs derived from various somatic cell types, VM-derived iPSCs (ViPSCs) exhibit a markedly higher propensity to spontaneously differentiate into beating cardiomyocytes as compared to genetically matched embryonic stem cells (ESCs) or iPSCs derived from tail-tip fibroblasts. Strikingly, the majority of ViPSC-derived cardiomyocytes display a ventricular phenotype. The enhanced ventricular myogenesis in ViPSCs is mediated via increased numbers of cardiovascular progenitors at early stages of differentiation. In order to investigate the mechanism of enhanced ventricular myogenesis from ViPSCs, we performed global gene expression and DNA methylation analysis, which revealed a distinct epigenetic signature that may be involved in specifying the VM fate in pluripotent stem cells.     

Induced Pluripotency for Translational Research

The advent of induced pluripotent stem cells （iPSCs） has revolutionized the concept of cellular reprogramming and potentially will solve the immunological compatibility issues that have so far hindered the application of human pluripotent stem cells in regenerative medicine. Recent findings showed that pluripotency is defined by a state of balanced lineage potency, which can be artificially instated through various procedures, including the conventional Yamanaka strategy. As a type of pluripotent stem cell, iPSCs are subject to the usual concerns over purity of differen- tiated derivatives and risks of tumor formation when used for cell-based therapy, though they pro- vide certain advantages in translational research, especially in the areas of personalized medicine, disease modeling and drug screening, iPSC-based technology, human embryonic stem cells （hESCs） and direct lineage conversion each will play distinct roles in specific aspects of translational medi- cine, and continue yielding surprises for scientists and the public.     

诱导型多能干细胞iPSc研究现状及其移植治疗帕金森综合症应用前景

诱导多能干细胞(i PS细胞)在小鼠和人上的成功获取,使干细胞领域的研究进入了一个崭新的时代。干细胞研究是再生医学的重要组成部分,研究干细胞的最终目的是应用干细胞治疗疾病,其在疾病模型建立、药物筛选、细胞移植等方面具有极大的应用潜力。i PSCs是由体细胞诱导分化而成的"多能细胞",具备和胚胎干细胞类似的功能,既解决了ESCs的伦理障碍,又为ESCs的获得提供了一条全新的途径,具有重要的理论和应用价值。i PS细胞不仅打破了道德理论的束缚,而且在再生医学、组织工程和药物发现及评价等方面具有积极的价值。神经系统遗传性疾病发病率居各系统遗传病之首,但其发病的分子机制仍不完全清楚,运用体细胞重编程技术建立的疾病特异性诱导多能干细胞模型将有助于揭示神经系统遗传性疾病的发病机理。近几年i PS细胞最新研究成果表明,利用疾病患者i PS细胞模型已逐渐应用于帕金森氏病、老年性痴呆症、脊髓侧索硬化症、脊髓肌肉萎缩症及舞蹈症等5种常见神经性退行性疾病发病机理的研究。本文主要对i PSc的发展历程,避免病毒基因干扰诱导i PS细胞进行的优化,以及干细胞尤其是i PS细胞移植治疗帕金森病等神经系统疾病的现状及应用前景进行系统阐述与论证。     

Modeling of hemophilia A using patient-specific induced pluripotent stem cells derived from urine cells

Aims

Hemophilia A (HA) is a severe, congenital bleeding disorder caused by the deficiency of clotting factor VIII (FVIII). For years, traditional laboratory animals have been used to study HA and its therapies, although animal models may not entirely mirror the human pathophysiology. Human induced pluripotent stem cells (iPSCs) can undergo unlimited self-renewal and differentiate into all cell types. This study aims to generate hemophilia A (HA) patient-specific iPSCs that differentiate into disease-affected hepatocyte cells. These hepatocytes are potentially useful for in vitro disease modeling and provide an applicable cell source for autologous cell therapy after genetic correction.

Main methods

In this study, we mainly generated iPSCs from urine collected from HA patients with integration-free episomal vectors PEP4-EO2S-ET2K containing human genes OCT4, SOX2, SV40LT and KLF4, and differentiated these iPSCs into hepatocyte-like cells. We further identified the genetic phenotype of the FVIII genes and the FVIII activity in the patient-specific iPSC derived hepatic cells.

Key findings

HA patient-specific iPSCs (HA-iPSCs) exhibited typical pluripotent properties evident by immunostaining, in vitro assays and in vivo assays. Importantly, we showed that HA-iPSCs could differentiate into functional hepatocyte-like cells and the HA-iPSC-derived hepatocytes failed to produce FVIII, but otherwise functioned normally, recapitulating the phenotype of HA disease in vitro.

Significance

HA-iPSCs, particular those generated from the urine using a non-viral approach, provide an efficient way for modeling HA in vitro. Furthermore, HA-iPSCs and their derivatives serve as an invaluable cell source that can be used for gene and cell therapy in regenerative medicine.     

Impact of induced pluripotent stem cells on the study of central nervous system disease

The derivation of pluripotent stem cells from somatic tissues has provided researchers with a source of patient-specific stem cells. The potential applications of this technology are truly momentous, and include cellular modeling of disease processes, drug discovery, and cell-based therapy. Here, we review the use of induced pluripotent stem cells (iPSCs) to study CNS disease. Since the iPSC field is still in its infancy, we also discuss some of the challenges that will need to be overcome before the potential of this technology to study and to treat neurological and psychiatric disorders can be fully harnessed.     

iPSC technology-Powerful hand for disease modeling and therapeutic screen

Cardiovascular and neurodegenerative diseases are major health threats in many developed countries. Recently, target tissues derived from human embryonic stem (hES) cells and induced pluripotent stem cells (iPSCs), such as cardiomyocytes (CMs) or neurons, have been actively mobilized for drug screening. Knowledge of drug toxicity and efficacy obtained using stem cell-derived tissues could parallel that obtained from human trials. Furthermore, iPSC disease models could be advantageous in the development of personalized medicine in various parts of disease sectors. To obtain the maximum benefit from iPSCs in disease modeling, researchers are now focusing on aging, maturation, and metabolism to recapitulate the pathological features seen in patients. Compared to pediatric disease modeling, adult-onset disease modeling with iPSCs requires proper maturation for full manifestation of pathological features. Herein, the success of iPSC technology, focusing on patient-specific drug treatment, maturation-based disease modeling, and alternative approaches to compensate for the current limitations of patient iPSC modeling, will be further discussed. [BMB Reports 2015; 48(5): 256-265]     

iPS cells: a game changer for future medicine

The induced pluripotent stem cell (iPSC) technology is instrumental in advancing the fields of disease modeling and cell transplantation. We herein discuss the various issues regarding disease modeling and cell transplantation presented in previous reports, and also describe new iPSC‐based medicine including iPSC clinical trials. In such trials, iPSCs from patients can be used to predict drug responders/non‐responders by analyzing the efficacy of the drug on iPSC‐derived cells. They could also be used to stratify patients after actual clinical trials, including those with sporadic diseases, based on the drug responsiveness of each patient in the clinical trials. iPSC‐derived cells can be used for the identification of response markers, leading to increased success rates in such trials. Since iPSCs can be used in micromedicine for drug discovery, and in macromedicine for actual clinical trials, their use would tightly connect both micro‐ and macromedicine. The use of iPSCs in disease modeling, cell transplantation, and clinical trials could therefore lead to significant changes in the future of medicine.     

Induced pluripotency and direct reprogramming: a new window for treatment of neurodegenerative diseases

Human embryonic stem cells (hESCs) are pluripotent cells that have the ability of unlimited self-renewal and can be differentiated into different cell lineages, including neural stem (NS) cells. Diverse regulatory signaling pathways of neural stem cells differentiation have been discovered, and this will be of great benefit to uncover the mechanisms of neuronal differentiation in vivo and in vitro. However, the limitations of hESCs resource along with the religious and ethical concerns impede the progress of ESCs application. Therefore, the induced pluripotent stem cells (iPSCs) via somatic cell reprogramming have opened up another new territory for regenerative medicine. iPSCs now can be derived from a number of lineages of cells, and are able to differentiate into certain cell types, including neurons. Patient-specific iPSCs are being used in human neurodegenerative disease modeling and drug screening. Furthermore, with the development of somatic direct reprogramming or lineage reprogramming technique, a more effective approach for regenerative medicine could become a complement for iPSCs.     

Directed differentiation of human pluripotent stem cells to cerebral cortex neurons and neural networks

Efficient derivation of human cerebral neocortical neural stem cells (NSCs) and functional neurons from pluripotent stem cells (PSCs) facilitates functional studies of human cerebral cortex development, disease modeling and drug discovery. Here we provide a detailed protocol for directing the differentiation of human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) to all classes of cortical projection neurons. We demonstrate an 80-d, three-stage process that recapitulates cortical development, in which human PSCs (hPSCs) first differentiate to cortical stem and progenitor cells that then generate cortical projection neurons in a stereotypical temporal order before maturing to actively fire action potentials, undergo synaptogenesis and form neural circuits in vitro. Methods to characterize cortical neuron identity and synapse formation are described.     

Genetic correction of Huntington's disease phenotypes in induced pluripotent stem cells

Huntington's disease (HD) is caused by a CAG expansion in the huntingtin gene. Expansion of the polyglutamine tract in the huntingtin protein results in massive cell death in the striatum of HD patients. We report that human induced pluripotent stem cells (iPSCs) derived from HD patient fibroblasts can be corrected by the replacement of the expanded CAG repeat with a normal repeat using homologous recombination, and that the correction persists in iPSC differentiation into DARPP-32-positive neurons in vitro and in vivo. Further, correction of the HD-iPSCs normalized pathogenic HD signaling pathways (cadherin, TGF-β, BDNF, and caspase activation) and reversed disease phenotypes such as susceptibility to cell death and altered mitochondrial bioenergetics in neural stem cells. The ability to make patient-specific, genetically corrected iPSCs from HD patients will provide relevant disease models in identical genetic backgrounds and is a critical step for the eventual use of these cells in cell replacement therapy.     

诱导多能干细胞在帕金森病治疗中的应用进展

帕金森病（Parkinson's disease, PD）是由于黑质中多巴胺能神经元（dopaminergic neurons, DAns）的病变导致多巴胺含量降低而引起的一种神经退行性疾病,其发病机制尚不明确,而且临床缺乏有效的早期诊断和治疗手段。诱导多能干细胞（induced pluripotent stem cells, iPSCs）的出现为神经系统疾病特别是神经退行性疾病的治疗带来了希望。基于iPSCs的细胞模型可以广泛开展PD发病机制的研究,同时以iPSCs来源的DAns、神经干细胞（neural stem cells, NSCs）等的细胞移植治疗,更是未来PD治疗最有希望的手段。从基于iPSCs的不同基因突变类型的细胞模型与不同分化程度的细胞移植治疗两个方面介绍诱导多能干细胞在PD研究中的进展,旨在分析诱导多能干细胞在帕金森病方面的应用及不足。     

Induced pluripotent stem cells (iPSCs) as game-changing tools in the treatment of neurodegenerative disease: Mirage or reality?

Based on investigations, there exist tight correlations between neurodegenerative diseases' incidence and progression and aberrant protein aggregreferates in nervous tissue. However, the pathology of these diseases is not well known, leading to an inability to find an appropriate therapeutic approach to delay occurrence or slow many neurodegenerative diseases' development. The accessibility of induced pluripotent stem cells (iPSCs) in mimicking the phenotypes of various late-onset neurodegenerative diseases presents a novel strategy for in vitro disease modeling. The iPSCs provide a valuable and well-identified resource to clarify neurodegenerative disease mechanisms, as well as prepare a promising human stem cell platform for drug screening. Undoubtedly, neurodegenerative disease modeling using iPSCs has established innovative opportunities for both mechanistic types of research and recognition of novel disease treatments. Most important, the iPSCs have been considered as a novel autologous cell origin for cell-based therapy of neurodegenerative diseases following differentiation to varied types of neural lineage cells (e.g. GABAergic neurons, dopamine neurons, cortical neurons, and motor neurons). In this review, we summarize iPSC-based disease modeling in neurodegenerative diseases including Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, and Huntington's disease. Moreover, we discuss the efficacy of cell-replacement therapies for neurodegenerative disease.     

Induced pluripotent stem cells and Parkinson's disease: modelling and treatment

Many neurodegenerative disorders, such as Parkinson's disease (PD), are characterized by progressive neuronal loss in different regions of the central nervous system, contributing to brain dysfunction in the relevant patients. Stem cell therapy holds great promise for PD patients, including with foetal ventral mesencephalic cells, human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSCs). Moreover, stem cells can be used to model neurodegenerative diseases in order to screen potential medication and explore their mechanisms of disease. However, related ethical issues, immunological rejection and lack of canonical grafting protocols limit common clinical use of stem cells. iPSCs, derived from reprogrammed somatic cells, provide new hope for cell replacement therapy. In this review, recent development in stem cell treatment for PD, using hiPSCs, as well as the potential value of hiPSCs in modelling for PD, have been summarized for application of iPSCs technology to clinical translation for PD treatment.     

Skeletal muscle generated from induced pluripotent stem cells-induction and application

Human induced pluripotent stem cells(hiPS cells or hiPSCs) can be derived from cells of patients with severe muscle disease. If skeletal muscle induced from patientiPSCs shows disease-specific phenotypes, it can be useful for studying the disease pathogenesis and for drug development. On the other hand, human iPSCs from healthy donors or hereditary muscle diseaseiPSCs whose genomes are edited to express normal protein are expected to be a cell source for cell therapy. Several protocols for the derivation of skeletal muscle from human iPSCs have been reported to allow the development of efficient treatments for devastating muscle diseases. In 2017, the focus of research is shifting to another stage:(1) the establishment of mature myofibers that are suitable for study of the pathogenesis of muscle disease;(2) setting up a highthroughput drug screening system; and(3) the preparation of highly regenerative, non-oncogenic cells in large quantities for cell transplantation, etc.     

Epigenetic memory and preferential lineage-specific differentiation in induced pluripotent stem cells derived from human pancreatic islet beta cells

Human induced pluripotent stem cells (HiPSCs) appear to be highly similar to human embryonic stem cells (HESCs). Using two genetic lineage-tracing systems, we demonstrate the generation of iPSC lines from human pancreatic islet beta cells. These reprogrammed cells acquired markers of pluripotent cells and differentiated into the three embryonic germ layers. However, the beta cell-derived iPSCs (BiPSCs) maintained open chromatin structure at key beta-cell genes, together with?a unique DNA methylation signature that distinguishes them from other PSCs. BiPSCs also demonstrated an increased ability to differentiate into insulin-producing cells both in?vitro and in?vivo, compared with ESCs and isogenic non-beta iPSCs. Our results suggest that the epigenetic memory may predispose?BiPSCs to differentiate more readily into insulin producing cells. These findings demonstrate that HiPSC phenotype may be influenced by their cells of origin, and suggest that their skewed differentiation potential may be advantageous for cell replacement therapy.     

多能干细胞向雄性生殖细胞定向分化的研究进展

生殖健康是生命科学领域关注的核心之一,各种原因所致男性不育亟待解决,然而由于伦理限制等原因,缺少合适的具有人类遗传背景的研究模型开展研究。胚胎干细胞（ESCs）和诱导多能干细胞（iPSCs）均属于多能干细胞,具有多向分化潜能。一方面,可利用ESCs?/?iPSCs向生殖细胞分化的模型研究人类生殖细胞的发育规律,另一方面,在此基础上,可建立带有人类疾病遗传背景的iPSCs模型,体外诱导其向雄性生殖细胞分化,利用该模型研究男性不育的发病机制。由于精子在体内的形成遵循一定规律,体外环境中不同发育阶段的生殖细胞在不同诱导因子作用下才可稳定地往下一阶段定向分化,因此,诱导ESCs?/?iPSCs向雄性生殖细胞方向分化时,诱导因子的种类和加入时间的选择应根据生殖细胞的体内发育特征而定,并且在诱导的不同阶段循序加入,以此模拟精子在体内的形成过程,进而更好地研究男性不育的发病机制。本文将对多能干细胞向雄性生殖细胞定向分化的常用诱导因子及存在问题和展望进行综述,为相关研究的开展提供借鉴。