Pluripotent stem cells capture the imagination since they can differentiate into all cell types in our body. Recent evidence suggests that in ad- dition to embryonic stem cells （ESCs） and epiblast ...stem cells （EpiSCs）, a new type of region-selective pluripotent stem cells （rsPSCs） exists, possessing unique spatial and molecular characteristics.
The International Society for Stem Cell Research (ISSCR) presents its 2016 Guidelines for Stem Cell Research and Clinical Translation (ISSCR, 2016). The 2016 guidelines reflect the revision and ...extension of two past sets of guidelines (ISSCR, 2006; ISSCR, 2008) to address new and emerging areas of stem cell discovery and application and evolving ethical, social, and policy challenges. These guidelines provide an integrated set of principles and best practices to drive progress in basic, translational, and clinical research. The guidelines demand rigor, oversight, and transparency in all aspects of practice, providing confidence to practitioners and public alike that stem cell science can proceed efficiently and remain responsive to public and patient interests. Here, we highlight key elements and recommendations in the guidelines and summarize the recommendations and deliberations behind them.
•The ISSCR presents its new Guidelines for Stem Cell Research and Clinical Translation•The guidelines outline core principles and best practices for the field•Recommendations drive rigor and transparency in all aspects of stem cell research•The guidelines build widespread confidence in the integrity of the research enterprise
The International Society for Stem Cell Research (ISSCR) presents its 2016 Guidelines for Stem Cell Research and Clinical Translation (ISSCR, 2016). The 2016 guidelines reflect the revision and extension of two past sets of guidelines (ISSCR, 2006; ISSCR, 2008) to address new and emerging areas of stem cell discovery and application and evolving ethical, social, and policy challenges. These guidelines provide an integrated set of principles and best practices to drive progress in basic, translational, and clinical research. The guidelines demand rigor, oversight, and transparency in all aspects of practice, providing confidence to practitioners and public alike that stem cell science can proceed efficiently and remain responsive to public and patient interests. Here, we highlight key elements and recommendations in the guidelines and summarize the recommendations and deliberations behind them.
Unprecedented developments in stem cell research herald a new era of hope and expectation for novel therapies. However, they also present a major challenge for regulators since safety assessment ...criteria, designed for conventional agents, are largely inappropriate for cell-based therapies. This article aims to set out the safety issues pertaining to novel stem cell-derived treatments, to identify knowledge gaps that require further research, and to suggest a roadmap for developing safety assessment criteria. It is essential that regulators, pharmaceutical providers, and safety scientists work together to frame new safety guidelines, based on “acceptable risk,” so that patients are adequately protected but the safety “bar” is not set so high that exciting new treatments are lost.
depletion is associated with the multisystemic neurodegenerative syndrome ataxia-telangiectasia (A-T). The exact linkage between neurodegeneration and
deficiency has not been established yet, and no ...treatment is currently available. In this study, we aimed to identify synthetic viable genes in
deficiency to highlight potential targets for the treatment of neurodegeneration in A-T. We inhibited ATM kinase activity using the background of a genome-wide haploid pluripotent CRISPR/Cas9 loss-of-function library and examined which mutations confer a growth advantage on
-deficient cells specifically. Pathway enrichment analysis of the results revealed the Hippo signaling pathway as a major negative regulator of cellular growth upon ATM inhibition. Indeed, genetic perturbation of the Hippo pathway genes
and
, as well as chemical inhibition of this pathway, specifically promoted the growth of
-knockout cells. This effect was demonstrated in both human embryonic stem cells and neural progenitor cells. Therefore, we suggest the Hippo pathway as a candidate target for the treatment of the devastating cerebellar atrophy associated with A-T. In addition to the Hippo pathway, our work points out additional genes, such as the apoptotic regulator
, as synthetic viable with
-deficiency. These genes may help to develop drugs for the treatment of A-T patients as well as to define biomarkers for resistance to
inhibition-based chemotherapies and to gain new insights into the
genetic network.
Genomic imprinting is an epigenetic mechanism that results in parent-of-origin monoallelic expression of specific genes, which precludes uniparental development and underlies various diseases. Here, ...we explored molecular and developmental aspects of imprinting in humans by generating exclusively paternal human androgenetic embryonic stem cells (aESCs) and comparing them with exclusively maternal parthenogenetic ESCs (pESCs) and bi-parental ESCs, establishing a pluripotent cell system of distinct parental backgrounds. Analyzing the transcriptomes and methylomes of human aESCs, pESCs, and bi-parental ESCs enabled the characterization of regulatory relations at known imprinted regions and uncovered imprinted gene candidates within and outside known imprinted regions. Investigating the consequences of uniparental differentiation, we showed the known paternal-genome preference for placental contribution, revealed a similar bias toward liver differentiation, and implicated the involvement of the imprinted gene IGF2 in this process. Our results demonstrate the utility of parent-specific human ESCs for dissecting the role of imprinting in human development and disease.
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•Generation of human androgenetic and parthenogenetic ESCs (aESCs and pESCs)•Comparing aESCs and pESCs identifies known and formerly undescribed imprinted genes•The uniparental cells show tissue-specific parent-of-origin differentiation biases•The imprinted gene IGF2 is involved in hepatic differentiation bias of human aESCs
Benvenisty, Egli, and colleagues combine newly derived human androgenetic ESCs with parthenogenetic and bi-parental ESCs to explore parental imprinting in humans, charting the regulatory landscape of known imprinted loci, identifying previously undescribed imprinted genes, and interrogating the nature and mechanisms underlying parental-origin-driven tissue-specific differentiation biases with implications for human development and disease.
Experimental modelling of human disorders enables the definition of the cellular and molecular mechanisms underlying diseases and the development of therapies for treating them. The availability of ...human pluripotent stem cells (PSCs), which are capable of self-renewal and have the potential to differentiate into virtually any cell type, can now help to overcome the limitations of animal models for certain disorders. The ability to model human diseases using cultured PSCs has revolutionized the ways in which we study monogenic, complex and epigenetic disorders, as well as early- and late-onset diseases. Several strategies are used to generate such disease models using either embryonic stem cells (ES cells) or patient-specific induced PSCs (iPSCs), creating new possibilities for the establishment of models and their use in drug screening.
Human embryonic stem cells are pluripotent cells that can serve as a cell source for transplantation medicine, and as a tool to study human embryogenesis. We investigate here the potential of human ...embryonic stem cells to differentiate into hepatic cells. We have characterized the expression level of liver-enriched genes in undifferentiated and differentiated human embryonic stem cells by DNA microarrays. Our analysis revealed a subset of fetal hepatic enriched genes that are expressed in human embryonic stem cells upon differentiation into embryoid bodies. In order to isolate the hepatic-like cells, we introduced a reporter gene regulated by a hepatocyte-specific promoter into human embryonic stem cells. We isolated clones of human embryonic stem cells that express enhanced green fluorescent protein upon
in vitro differentiation. Through immunostaining, we showed that most of these cells express albumin, while some cells still express the earlier expressed protein α-fetoprotein. Using fluorescence activated cell sorter, we were able to sort out the fluorescent differentiated cells and expand them for a few more weeks. This is the first report to demonstrate the possibility of purifying differentiated derivatives of human embryonic stem cells and culturing them further. Through confocal microscopy, we detected clusters of hepatic-like cells in 20-day-old embryoid bodies and in teratomas. As observed during embryonic development, we showed that in teratomas, the hepatic-like endodermal cells develop next to cardiac mesodermal cells. In order to examine the secreted factors involved in the induction of hepatic differentiation, human embryonic stem cells were grown in the presence of various growth factors, demonstrating the potential involvement of acidic fibroblast growth factor in the differentiation. In conclusion, given certain growth conditions and genetic manipulation, we can now differentiate and isolate hepatic-like cells from human embryonic stem cells.
Human embryonic stem (ES) cells are pluripotent cells derived from blastocyst-stage embryos. It has been suggested that these cells should play a major role in transplantation medicine and be able to ...advance our knowledge in human embryology. We propose that these cells should also play a vital role in the creation of models of human disorders. This aspect would be most valuable where animal models failed to faithfully recapitulate the human phenotype. Lesch-Nyhan disease is caused by a mutation in the HPRT1 gene that triggers an overproduction of uric acid, causing gout-like symptoms and urinary stones, in addition to neurological disorders. Due to biochemical differences between humans and rodents, a mouse lacking the HPRT expression will fail to accumulate uric acid. In this research we demonstrate a model for Lesch-Nyhan disease by mutating the HPRT1 gene in human ES cells using homologous recombination. We have verified the mutation in the HPRT1 allele at the DNA and RNA levels. By using selection media, we show that HPRT1 activity is abolished in the mutant cells, and the HPRT1-cells show a higher rate of uric acid accumulation than the wild-type cells. Therefore, these cells recapitulate to some extent the characteristics of Lesch-Nyhan syndrome and can help researchers further investigate this genetic disease and analyze drugs that will prevent the onset of its symptoms. We therefore suggest that human diseases may be modeled using human ES cells.
Teratoma formation is the gold standard assay for testing the capacity of human pluripotent stem cells to differentiate into all embryonic germ layers. Although widely used, little effort has been ...made to transform this qualitative assay into a quantitative one. Using gene expression data from a wide variety of cells, we created a scorecard representing tissues from all germ layers and extraembryonic tissues. TeratoScore, an online, open-source platform based on this scorecard, distinguishes pluripotent stem cell-derived teratomas from malignant tumors, translating cell potency into a quantitative measure (http://benvenisty.huji.ac.il/teratoscore.php). The teratomas used for the algorithm also allowed us to examine gene expression differences between tumors with a diploid karyotype and those initiated by aneuploid cells. Chromosomally aberrant teratomas show a significantly different gene expression signature from that of teratomas originating from diploid cells, particularly in central nervous system-specific genes, congruent with human chromosomal syndromes.
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•A gene scorecard representing human tissues from all germ layers was created•A quantitative pluripotency test named TeratoScore was based on this scorecard•TeratoScore distinguishes pluripotent stem cell-derived teratomas from other tumors•Teratomas derived from aneuploid cells show aberrant tissue expression distribution
Teratoma formation is a gold standard assay when defining pluripotency of cells. In this paper, Benvenisty and colleagues utilized global gene expression analysis to transform the qualitative character of this assay into a quantitative one, replacing histological assessment of pluripotent capabilities. Moreover, they show that teratomas initiated from aneuploid cells show an aberrant tissue expression distribution, characteristic of their developmental defects.
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