The promise of human induced pluripotent stem cells for research and therapy

Induced pluripotent stem (iPS) cells are human somatic cells that have been reprogrammed to a pluripotent state. There are several hurdles to be overcome before iPS cells can be considered as a potential patient-specific cell therapy, and it will be crucial to characterize the developmental potential of human iPS cell lines. As a research tool, iPS-cell technology provides opportunities to study normal development and to understand reprogramming. iPS cells can have an immediate impact as models for human diseases, including cancer     

Establishment of induced pluripotent stem cells from human neonatal tissues

Following the success in establishing human induced pluripotent stem (iPS) cells, research into various applications of the cells derived from human iPS cells has begun in earnest. The use of iPS cell-derived cells in clinical therapies is one of the most exciting of the possible applications. However, the risk of tumorigenicity is the biggest potential obstacle to use iPS cell derivatives in the clinic. It should be noted that the human cells used to generate iPS cell lines may have acquired genetic mutations and these might influence the tumorigenicity of the cells. In particular, the cells of older people have a higher risk of genetic mutations than those of younger people. Here, we show that iPS cells could be derived from short-term cultures of neonatal tissues. The established human iPS cells expressed various markers of undifferentiated cells and formed teratoma in immunodeficient mice. The human iPS cells derived from neonatal tissues may represent a clinical material possessing less tumorigenicity.     

Mouse meningiocytes express Sox2 and yield high efficiency of chimeras after nuclear reprogramming with exogenous factors

Induced pluripotent stem cell technology, also termed iPS, is an emerging approach to reprogram cells into an embryonic stem cell-like state by viral transduction with defined combinations of factors. iPS cells share most characteristics of embryonic stem cells, counting pluripotency and self-renewal, and have so far been obtained from mouse and humans, including patients with genetic diseases. Remarkably, autologous transplantation of cell lineages derived from iPS cells will eliminate the possibility of immunological rejection, as well as current ethical issues surrounding human embryonic stem cell research. However, before iPS can be used for clinical purposes, technical problems must be overcome. Among other considerations, full and homogeneous iPS reprogramming is an important prerequisite. However, despite the fact that cells from several mouse tissues can be successfully induced to iPS, the overall efficiency of chimera formation of these clones remains low even if selection for Oct4 or Nanog expression is applied. In this report, we demonstrate that cells from the mouse meningeal membranes express elevated levels of the embryonic master regulator Sox2 and are highly amenable to iPS. Meningeal iPS clones, generated without selection, are fully and homogeneously reprogrammed based on DNA methylation analysis and 100% chimera competent. Our results define a population of somatic cells that are ready to undergo iPS, thus highlighting a very attractive cell type for iPS research and application.     

SNL fibroblast feeder layers support derivation and maintenance of human induced pluripotent stem cells

Induced pluripotent stem(iPS) cells can be derived from human somatic cells by cellular reprogramming.This technology provides a potential source of non-controversial therapeutic cells for tissue repair,drug discovery,and opportunities for studying the molecular basis of human disease.Normally,mouse embryonic fibroblasts(MEFs) are used as feeder layers in the initial derivation of iPS lines.The purpose of this study was to determine whether SNL fibroblasts can be used to support the growth of human iPS cell...     

Generation of insulin-secreting islet-like clusters from human skin fibroblasts

Increasing evidence suggests that islet cell transplantation for patients with type I diabetes holds great promise for achieving insulin independence. However, the extreme shortage of matched organ donors and the necessity for chronic immunosuppression has made it impossible for this treatment to be used for the general diabetic population. Recent success in generating insulin-secreting islet-like cells from human embryonic stem (ES) cells, in combination with the success in deriving human ES cell-like induced pluripotent stem (iPS) cells from human fibroblasts by defined factors, have raised the possibility that patient-specific insulin-secreting islet-like cells might be derived from somatic cells through cell fate reprogramming using defined factors. Here we confirm that human ES-like iPS cells can be derived from human skin cells by retroviral expression of OCT4, SOX2, c-MYC, and KLF4. Importantly, using a serum-free protocol, we successfully generated insulin-producing islet-like clusters (ILCs) from the iPS cells under feeder-free conditions. We demonstrate that, like human ES cells, skin fibroblast-derived iPS cells have the potential to be differentiated into islet-like clusters through definitive and pancreatic endoderm. The iPS-derived ILCs not only contain C-peptide-positive and glucagon-positive cells but also release C-peptide upon glucose stimulation. Thus, our study provides evidence that insulin-secreting ILCs can be generated from skin fibroblasts, raising the possibility that patient-specific iPS cells could potentially provide a treatment for diabetes in the future.     

Comparative study of myocytes from normal and mdx mice iPS cells

Recently, induced pluripotent stem cells (iPS cells) have been derived from various techniques and show great potential for therapy of human diseases. Furthermore, the iPS technique can be used to provide cell models to explore pathological mechanisms of many human diseases in vitro, such as Duchenne muscular dystrophy (DMD), which is a severe recessive X-linked form of muscular dystrophy without effective treatment. In this study, we try to determine whether there are different characteristics of myocytes from mdx iPS cells and C57BL/10 iPS cells. Our results showed that both of mdx and C57BL/10 cells could be induced into iPS cells in vitro, whereas colony-forming ability of mdx iPS cells was much weaker than that of C57BL/10 iPS cells. Meanwhile, mdx iPS cells could be induced to differentiate into myocytes, whereas their differentiation efficiency was much lower than that of C57BL/10 iPS cells. And, the number of apoptotic cells in differentiated myocytes from mdx iPS cells was significantly higher than that from C57BL/10 iPS cells. More importantly, treatment of a pan-caspase inhibitor (Z-VAD) produced a significant decrease in apoptotic cells. This study might add some insight to the biology study of dystrophin gene.     

Human-Induced Pluripotent Stem Cells: In Quest of Clinical Applications

In the field of regenerative medicine, the development of induced pluripotent stem (iPS) cells may represent a potential strategy to overcome the limitations of human embryonic stem cells (ESCs). iPS cells have the potential to mimic human disease, since they carry the genome of the donor. Hypothetically, with iPS cell technology it is possible to screen patients for a genetic cause of disease (genetic mutation), develop cell lines, reprogram them back to iPS cells, finally differentiate them into one or more cell types that develop the disease. Although the creation of multiple lineages with iPS cells can seem limitless, a number of challenges need to be addressed in order to effectively use these cell lines for disease modeling. These include the low efficiency of iPS cell generation without genetic alterations, the possibility of tumor formation in vivo, the random integration of retroviral-based delivery vectors into the genome, and unregulated growth of the remaining cells that are partially reprogrammed and refractory to differentiation. The establishment of protein or RNA-based reprogramming strategies will help generate human iPS cells without permanent genetic alterations. Finally, direct reprogramming strategies can provide rapid production of models of human ??diseases in a dish??, without first passing the cells through a pluripotent state, so avoiding the challenges of time-consumming and labor-intensive iPS cell line generation. This review will overview methods to develop iPS cells, current strategies for direct reprogramming, and main applications of iPS cells as human disease model, focusing on human cardiovascular diseases, with the aim to be a potential information resource for biomedical scientists and clinicians who exploit or intend to exploit iPS cell technology in a range of applications.     

SNL fibroblast feeder layers support derivation and maintenance of human induced pluripotent stem cells

Induced pluripotent stem(iPS)cells can be derived from human somatic cells by cellular reprogramming.This technology provides a potential source of non-controversial therapeutic cells for tissue repair,drug discovery,and opportunities for studying the molecular basis of human disease.Normally,mouse embryonic fibroblasts(MEFs)are used as feeder layers in the initial derivation of iPS lines.The purpose of this study was to determine whether SNL fibroblasts can be used to support the growth of human iPS cells reprogrammed from somatic cells using lentivirai expressed reprogramming factors.In our study,iPS cells expressed common pluripotency markers,displayed human embryonic stern cells(hESCs)morphology and unmethylated promoters of NANOG and OCT4.These data demonstrate that SNL feeder cells can support the derivation and maintenance of human iPS cells.     

Multiple sclerosis: getting personal with induced pluripotent stem cells

Human induced pluripotent stem (iPS) cells can be derived from lineage-restricted cells and represent an important tool to develop novel patient-specific cell therapies and research models for inherited and acquired diseases. Recently, patient-derived iPS cells, containing donor genetic background, have offered a breakthrough approach to study human genetics of neurodegenerative diseases. By offering an unlimited source of patient-specific disease-relevant cells, iPS cells hold great promise for understanding disease mechanisms, identifying molecular targets and developing phenotypic screens for drug discovery. This review will discuss the potential impact of using iPS cell-derived models in multiple sclerosis (MS) research and highlight some of the current challenges and prospective for generating novel therapeutic treatments for MS patients.     

Generation,Purification and Transplantation of Photoreceptors Derived from Human Induced Pluripotent Stem Cells

Background

Inherited and acquired retinal degenerations are frequent causes of visual impairment and photoreceptor cell replacement therapy may restore visual function to these individuals. To provide a source of new retinal neurons for cell based therapies, we developed methods to derive retinal progenitors from human ES cells.

Methodology/Physical Findings

In this report we have used a similar method to direct induced pluripotent stem cells (iPS) from human fibroblasts to a retinal progenitor fate, competent to generate photoreceptors. We also found we could purify the photoreceptors derived from the iPS cells using fluorescence activated cell sorting (FACS) after labeling photoreceptors with a lentivirus driving GFP from the IRBP cis-regulatory sequences. Moreover, we found that when we transplanted the FACS purified iPSC derived photoreceptors, they were able to integrate into a normal mouse retina and express photoreceptor markers.

Conclusions

This report provides evidence that enriched populations of human photoreceptors can be derived from iPS cells.     

Reprogramming the pluripotent cell cycle: restoration of an abbreviated G1 phase in human induced pluripotent stem (iPS) cells

Induced pluripotent stem (iPS) cells derived from terminally differentiated human fibroblasts are reprogrammed to possess stem cell like properties. However, the extent to which iPS cells exhibit unique properties of the human embryonic stem (hES) cell cycle remains to be established. hES cells are characterized by an abbreviated G1 phase (～ 2.5 h) and accelerated organization of subnuclear domains that mediate the assembly of regulatory machinery for histone gene expression [i.e., histone locus bodies (HLBs)]. We therefore examined cell cycle parameters of iPS cells in comparison to hES cells. Analysis of DNA synthesis [5-bromo-2'-deoxy-uridine (BrdU) incorporation], cell cycle distribution (FACS analysis and Ki67 staining) and subnuclear organization of HLBs [immunofluorescence microscopy and fluorescence in situ hybridization (FISH)] revealed that human iPS cells have a short G1 phase (～ 2.5 h) and an abbreviated cell cycle (16-18 h). Furthermore, HLBs are formed and reorganized rapidly after mitosis (within 1.5-2 h). Thus, reprogrammed iPS cells have cell cycle kinetics and dynamic subnuclear organization of regulatory machinery that are principal properties of pluripotent hES cells. Our findings support the concept that the abbreviated cell cycle of hES and iPS cells is functionally linked to pluripotency.     

Pluripotency of Induced Pluripotent Stem Cells

Induced pluripotent stem （iPS） cells can be generated by forced expression of four pluripotency factors in somatic cells. This has received much attention in recent years since it may offer us a promising donor cell source for cell transplantation therapy. There has been great progress in iPS cell research in the past few years. However, several issues need to be further addressed in the near future before the clinical application of iPS cells, like the immunogenieity of iPS cells, the variability of differentiation potential and most importantly tumor formation of the iPS derivative cells. Here, we review recent progress in research into the pluripotency of iPS cells.     

Induced pluripotent stem cells from swine (Sus scrofa): Why they may prove to be important

Three recent papers, published almost simultaneously by different groups, have described the generation of induced pluripotent stem (iPS) cells from the pig, a species whose size, anatomy, and physiology render them attractive as clinical models for the human. The approach used in each case was to infect somatic cells with integrating retroviral vectors designed to express four reprogramming genes (POU5F1, SOX2, cMYC and KLF4). The cell lines generated met the standard criteria for pluripotency, including the ability to differentiate along multiple tissue lineages. In most respects, the porcine iPS cells more resembled human embryonic stem cells and human iPS cells than their murine equivalents. Provided such porcine iPS cells can be “personalized” to specific pigs and then coaxed to differentiate along specific lineages, it should be possible to use such animals to test transplantation therapies with iPS cells for safety and efficacy before the procedures are applied to human patients.     

The applications of induced pluripotent stem (iPS) cells in drug development

The introduction of induced pluripotent stem (iPS) cells has been a milestone in the field of regenerative medicine and drug discovery. iPS cells can provide a continuous and individualized source of stem cells and are considered to hold great potential for economically feasible personalized stem cell therapy. Various diseases might potentially be cured by iPS cell-based therapy including Parkinson’s disease, Alzheimer’s disease, Huntington disease, ischemic heart disease, diabetes and so on. Moreover, iPS cells derived from patients suffering from unique incurable diseases can be developed into patient- and disease-specific cell lines. These cells can be used as an effective approach to study the mechanisms of diseases, providing useful tools for drug discovery, development and evaluation. The development of suitable methods for the culture and expansion of iPS cells and their differentiated progenies make feasible modern drug discovery techniques such as high-throughput screening. Furthermore, iPS cells can be applied in the field of toxicological and pharmacokinetics tests. This review focuses on the applications of iPS cells in the field of pharmaceutical industry.     

Human parthenogenetic embryonic stem cells: one potential resource for cell therapy

Pluripotent stem cells derived from somatic cells through such processes as nuclear transfer or induced pluripotent stem (iPS) cells present an important model for biomedical research and provide potential resources for cell replacement therapies. However, the overall efficiency of the conversional nuclear transfer is very low and the safety issue remains a major concern for iPS cells. Embryonic stem cells (ESCs) generated from parthenogenetic embryos are one attractive alternative as a source of histocompatible cells and tissues for cell therapy. Recent studies on human parthenogenetic embryonic stem cells (hPG ESCs) have revealed that these ESCs are very similar to the hESCs derived from IVF or in vivo produced blastocysts in gene expression and other characteristics, but full differentiation and development potential of these hPG ESCs have to be further investigated before clinical research and therapeutic interventions. To generate various pluripotent stem cells, diverse reprogramming techniques and approaches will be developed and integrated. This may help elucidate the fundamental mechanisms underlying reprogramming and stem cell biology, and ultimately benefit cell therapy and regenerative medicine. Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA02A101).     

Making gametes from alternate sources of stem cells: past,present and future

Infertile couples including cancer survivors stand to benefit from gametes differentiated from embryonic or induced pluripotent stem (ES/iPS) cells. It remains challenging to convert human ES/iPS cells into primordial germ-like cells (PGCLCs) en route to obtaining gametes. Considerable success was achieved in 2016 to obtain fertile offspring starting with mouse ES/iPS cells, however the specification of human ES/iPS cells into PGCLCs in vitro is still not achieved. Human ES cells will not yield patient-specific gametes unless and until hES cells are derived by somatic cell nuclear transfer (therapeutic cloning) whereas iPS cells retain the residual epigenetic memory of the somatic cells from which they are derived and also harbor genomic and mitochondrial DNA mutations. Thus, they may not be ideal starting material to produce autologus gametes, especially for aged couples. Pluripotent, very small embryonic-like stem cells (VSELs) have been reported in adult tissues including gonads, are relatively quiescent in nature, survive oncotherapy and can be detected in aged, non-functional gonads. Being developmentally equivalent to PGCs (natural precursors to gametes), VSELs spontaneously differentiate into gametes in vitro. It is also being understood that gonadal stem cells niche is compromised by oncotherapy and with age. Improving the gonadal somatic niche could regenerate non-functional gonads from endogenous VSELs to restore fertility. Niche cells (Sertoli/mesenchymal cells) can be directly transplanted and restore gonadal function by providing paracrine support to endogenous VSELs. This strategy has been successful in several mice studies already and resulted in live birth in a woman with pre-mature ovarian failure.