Search

Today, human pluripotent stem cell technologies find widespread application across biomedical research, as models for early human development, as platforms for functional human genomics, as tools for the study of disease, drug screening and toxicology, and as a renewable source of cellular therapeutics for a range of intractable diseases. The foundations of this human pluripotent stem cell revolution rest on advances in a wide range of disciplines, including cancer biology, assisted reproduction, cell culture and organoid technology, somatic cell nuclear transfer, primate embryology, single-cell biology, and gene editing. This review surveys the slow emergence of the study of human pluripotency and the exponential growth of the field during the past several decades., (© 2024 Wiley Periodicals LLC.)

The power and scope of disease modeling can be markedly enhanced through the incorporation of broad genetic diversity. The introduction of pathogenic mutations into a single inbred mouse strain sometimes fails to mimic human disease. We describe a cross-species precision disease modeling platform that exploits mouse genetic diversity to bridge cell-based modeling with whole organism analysis. We developed a universal protocol that permitted robust and reproducible neural differentiation of genetically diverse human and mouse pluripotent stem cell lines and then carried out a proof-of-concept study of the neurodevelopmental gene DYRK1A . Results in vitro reliably predicted the effects of genetic background on Dyrk1a loss-of-function phenotypes in vivo. Transcriptomic comparison of responsive and unresponsive strains identified molecular pathways conferring sensitivity or resilience to Dyrk1a1A loss and highlighted differential messenger RNA isoform usage as an important determinant of response. This cross-species strategy provides a powerful tool in the functional analysis of candidate disease variants identified through human genetic studies.

Stem cells exist in vitro in a spectrum of interconvertible pluripotent states. Analyzing hundreds of hiPSCs derived from different individuals, we show the proportions of these pluripotent states vary considerably across lines. We discover 13 gene network modules (GNMs) and 13 regulatory network modules (RNMs), which are highly correlated with each other suggesting that the coordinated co-accessibility of regulatory elements in the RNMs likely underlie the coordinated expression of genes in the GNMs. Epigenetic analyses reveal that regulatory networks underlying self-renewal and pluripotency are more complex than previously realized. Genetic analyses identify thousands of regulatory variants that overlapped predicted transcription factor binding sites and are associated with chromatin accessibility in the hiPSCs. We show that the master regulator of pluripotency, the NANOG-OCT4 Complex, and its associated network are significantly enriched for regulatory variants with large effects, suggesting that they play a role in the varying cellular proportions of pluripotency states between hiPSCs. Our work bins tens of thousands of regulatory elements in hiPSCs into discrete regulatory networks, shows that pluripotency and self-renewal processes have a surprising level of regulatory complexity, and suggests that genetic factors may contribute to cell state transitions in human iPSC lines., (© 2024. The Author(s).)

The second week of embryonic development is a critical phase of the human life cycle and one that has been largely inaccessible to scientific investigation. Recent studies of human embryo models built from stem cells promise to yield dramatic insights into the key events of cell specification and morphogenesis that occur during this brief window of embryogenesis., Competing Interests: Declaration of interests The author declares no competing interests., (Copyright © 2023 Elsevier Inc. All rights reserved.)

A human embryo's legal definition and its entitlement to protection vary greatly worldwide. Recently, human pluripotent stem cells have been used to form in vitro models of early embryos that have challenged legal definitions and raised questions regarding their usage. In this light, we propose a refined legal definition of an embryo, suggest "tipping points" for when human embryo models could eventually be afforded similar protection to that of embryos, and then revisit basic ethical principles that might help to draft a roadmap for the gradual, justified usage of embryo models in a manner that aims to maximize benefits to society., Competing Interests: Declaration of interests N.C.R. is an inventor on the patents “Blastoid, cell line based artificial blastocyst” (EP2986711) and “Blastocyst-like cell aggregate and methods” (EP21151455.9) that are both licensed to dawn-bio, a company he co-founded. A.M.A. and N.M. are inventors on the patents "Polarised three-dimensional cellular aggregates” (PCT/GB2019/052668) and “human polarised three-dimensional cellular” (PCT/GB2019/052670), maintained by Cambridge Enterprise., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Importance: The COVID-19 pandemic has been associated with an elevated prevalence of mental health conditions and disrupted mental health care throughout the US., Objective: To examine mental health service use among US adults from January through December 2020., Design, Setting, and Participants: This cohort study used county-level service utilization data from a national US database of commercial medical claims from adults (age >18 years) from January 5 to December 21, 2020. All analyses were conducted in April and May 2021., Main Outcomes and Measures: Per-week use of mental health services per 10 000 beneficiaries was calculated for 5 psychiatric diagnostic categories: major depressive disorder (MDD), anxiety disorders, bipolar disorder, adjustment disorders, and posttraumatic stress disorder (PTSD). Changes in service utilization rates following the declaration of a national public health emergency on March 13, 2020, were examined overall and by service modality (in-person vs telehealth), diagnostic category, patient sex, and age group., Results: The study included 5 142 577 commercially insured adults. The COVID-19 pandemic was associated with more than a 50% decline in in-person mental health care service utilization rates. At baseline, there was a mean (SD) of 11.66 (118.00) weekly beneficiaries receiving services for MDD per 10 000 enrollees; this declined by 6.44 weekly beneficiaries per 10 000 enrollees (β, -6.44; 95% CI, -8.33 to -4.54). For other disorders, these rates were as follows: anxiety disorders (mean [SD] baseline, 12.24 [129.40] beneficiaries per 10 000 enrollees; β, -5.28; 95% CI, -7.50 to -3.05), bipolar disorder (mean [SD] baseline, 3.32 [60.39] beneficiaries per 10 000 enrollees; β, -1.81; 95% CI, -2.75 to -0.87), adjustment disorders (mean [SD] baseline, 12.14 [129.94] beneficiaries per 10 000 enrollees; β, -6.78; 95% CI, -8.51 to -5.04), and PTSD (mean [SD] baseline, 4.93 [114.23] beneficiaries per 10 000 enrollees; β, -2.00; 95% CI, -3.98 to -0.02). Over the same period, there was a 16- to 20-fold increase in telehealth service utilization; the rate of increase was lowest for bipolar disorder (mean [SD] baseline, 0.13 [16.72] beneficiaries per 10 000 enrollees; β, 1.40; 95% CI, 1.04-1.76) and highest for anxiety disorders (mean [SD] baseline, 0.20 [9.28] beneficiaries per 10 000 enrollees; β, 9.12; 95% CI, 7.32-10.92). When combining in-person and telehealth service utilization rates, an overall increase in care for MDD, anxiety, and adjustment disorders was observed over the period., Conclusions and Relevance: In this cohort study of US adults, we found that the COVID-19 pandemic was associated with a rapid increase in telehealth services for mental health conditions, offsetting a sharp decline in in-person care and generating overall higher service utilization rates for several mental health conditions compared with prepandemic levels.

3D patient tumor avatars (3D-PTAs) hold promise for next-generation precision medicine. Here, we describe the benefits and challenges of 3D-PTA technologies and necessary future steps to realize their potential for clinical decision making. 3D-PTAs require standardization criteria and prospective trials to establish clinical benefits. Innovative trial designs that combine omics and 3D-PTA readouts may lead to more accurate clinical predictors, and an integrated platform that combines diagnostic and therapeutic development will accelerate new treatments for patients with refractory disease., Competing Interests: Declarations of interests S.B., M.B., H.M., Z.P., C.A.M., K.M.N., M.F.P., R.C.S., K.S. and J.H.C. have no competing interests to declare. S.E.K. is an advisor to Xilis, Inc. F.M.B. declares consulting/advisory fees from AbbVie, Aduro BioTech Inc., Alkermes, AstraZeneca, Daiichi Sankyo Co. Ltd., DebioPharm, eFFECTOR Therapeutics, F. Hoffman-La Roche Ltd., Genentech Inc., Harbinger Health, IBM Watson, Infinity Pharmaceuticals, Jackson Laboratory, Kolon Life Science, Lengo Therapeutics, OrigiMed, PACT Pharma, Parexel International, Pfizer Inc., Protai Bio Ltd, Samsung Bioepis, Seattle Genetics Inc., Tallac Therapeutics, Tyra Biosciences, Xencor, Zymeworks, Black Diamond, Biovica, Eisai, FogPharma, Immunomedics, Inflection Biosciences, Karyopharm Therapeutics, Loxo Oncology, Mersana Therapeutics, OnCusp Therapeutics, Puma Biotechnology Inc., Seattle Genetics, Sanofi, Silverback Therapeutics, Spectrum Pharmaceuticals, and Zentalis; sponsored research to her institution from Aileron Therapeutics, Inc., AstraZeneca, Bayer Healthcare Pharmaceutical, Calithera Biosciences Inc., Curis Inc., CytomX Therapeutics Inc., Daiichi Sankyo Co. Ltd., Debiopharm International, eFFECTOR Therapeutics, Genentech Inc., Guardant Health Inc., Klus Pharma, Takeda Pharmaceutical, Novartis, Puma Biotechnology Inc., and Taiho Pharmaceutical Co.; and honoraria for a speaking engagement from Chugai Biopharmaceuticals. S.K. is a consultant for FGH BioTech and has received research funding from FGH BioTech and Systems Oncology. K.A.P. is co-inventor on a patent for EGFRT790M mutation testing issued, licensed, and with royalties paid from Molecular Diagnostics/Memorial Sloan Kettering Cancer Center. She reports research funding to the institution from AstraZeneca, Roche/Genentech, Boehringer Ingelheim, and D2G Oncology and consulting for AstraZeneca and Jannssen. M.G.C. reports grants from NeoImmuneTech, as well as other support from Orbus Therapeutics, Incyte, Merck, and UpToDate outside the submitted work; in addition, M.G.C. has a patent for Zika virus strains for the treatment of glioblastoma pending. E.E.’s full disclosures are given here: www.bit.ly/3xuWMer. J.T. reports personal financial interest in form of scientific consultancy role for Array Biopharma, AstraZeneca, Bayer, Boehringer Ingelheim, Chugai, Daiichi Sankyo, F. Hoffmann-La Roche Ltd, Genentech Inc, HalioDX SAS, Hutchison MediPharma International, Ikena Oncology, Inspirna Inc, IQVIA, Lilly, Menarini, Merck Serono, Merus, MSD, Mirati, Neophore, Novartis, Ona Therapeutics, Orion Biotechnology, Peptomyc, Pfizer, Pierre Fabre, Samsung Bioepis, Sanofi, Scandion Oncology, Scorpion Therapeutics, Seattle Genetics, Servier, Sotio Biotech, Taiho, Tessa Therapeutics, and TheraMyc; and holds stocks in Oniria Therapeutics and also educational collaboration with Imedex/HMP, Medscape Education, MJH Life Sciences, PeerView Institute for Medical Education and Physicians Education Resource (PER). D.A.T. is a member of the Scientific Advisory Board and receives stock options from Leap Therapeutics, Surface Oncology, Cygnal Therapeutics, Mestag Therapeutics, and Xilis, Inc. outside the submitted work. D.A.T. is scientific co-founder of Mestag Therapeutics. D.A.T. has received research grant support from Fibrogen, Mestag, and ONO Therapeutics. D.A.T. receives grant funding from the Lustgarten Foundation, the NIH, and the Thompson Foundation. None of this work is related to the publication. No other disclosures were reported. C.D.W. is a part-time consultant for LifeNet Health and receives grant funding from AACR-Novocure and Varian Medical Systems. X.S. and H.C. are cofounders of Xilis, Inc. and inventors on patents related to organoid research and micro-organospheres. X.S. is CEO of Xilis, Inc. H.C.’s full disclosure is given here: www.uu.nl/staff/JCClevers/Additionalfunctions. M.S., B.J.R., P.R., X.L., B.E.W., and A.L.W. do not report any conflicts., (Copyright © 2022 Elsevier Inc. All rights reserved.)

It is well established that human pluripotent stem cells (hPSCs) can acquire genetic and epigenetic changes during culture in vitro. Given the increasing use of hPSCs in research and therapy and the vast expansion in the number of hPSC lines available for researchers, the International Society for Stem Cell Research has recognized the need to reassess quality control standards for ensuring the genetic integrity of hPSCs. Here, we summarize current knowledge of the nature of recurrent genetic and epigenetic variants in hPSC culture, the methods for their detection, and what is known concerning their effects on cell behavior in vitro or in vivo. We argue that the potential consequences of low-level contamination of cell therapy products with cells bearing oncogenic variants are essentially unknown at present. We highlight the key challenges facing the field with particular reference to safety assessment of hPSC-derived cellular therapeutics., Competing Interests: Declaration of interests P.W.A. receives royalties from the Wistar Institute for sales of antibodies., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: COVID-19 vaccine distribution is at risk of further propagating the inequities of COVID-19, which in the United States (US) has disproportionately impacted the elderly, people of color, and the medically vulnerable. We sought to measure if the disparities seen in the geographic distribution of other COVID-19 healthcare resources were also present during the initial rollout of the COVID-19 vaccine., Methods: Using a comprehensive COVID-19 vaccine database (VaccineFinder), we built an empirically parameterized spatial model of access to essential resources that incorporated vaccine supply, time-willing-to-travel for vaccination, and previous vaccination across the US. We then identified vaccine deserts-US Census tracts with localized, geographic barriers to vaccine-associated herd immunity. We link our model results with Census data and two high-resolution surveys to understand the distribution and determinates of spatially accessibility to the COVID-19 vaccine., Results: We find that in early 2021, vaccine deserts were home to over 30 million people, >10% of the US population. Vaccine deserts were concentrated in rural locations and communities with a higher percentage of medically vulnerable populations. We also find that in locations of similar urbanicity, early vaccination distribution disadvantaged neighborhoods with more people of color and older aged residents., Conclusion: Given sufficient vaccine supply, data-driven vaccine distribution to vaccine deserts may improve immunization rates and help control COVID-19., (© 2022. The Author(s).)

Pluripotent stem cells provide a powerful model for the study of human development and its disorders. Recent studies, including two in this issue of Stem Cell Reports, raise important questions concerning the developmental potential of human pluripotent stem cells, and how the behavior of these cells in vitro mirrors normal embryogenesis., (Copyright © 2022 The Author. Published by Elsevier Inc. All rights reserved.)

Fluid and solute transporters of the retinal pigment epithelium (RPE) are core components of the outer blood-retinal barrier. Characterizing these transporters and their role in retinal homeostasis may provide insights into ocular function and disease. Here, we describe RPE defects in tvrm77 mice, which exhibit hypopigmented patches in the central retina. Mapping and nucleotide sequencing of tvrm77 mice revealed a disrupted 5' splice donor sequence in Slc4a5 , a sodium bicarbonate cotransporter gene. Slc4a5 expression was reduced 19.7-fold in tvrm77 RPE relative to controls, and alternative splice variants were detected. SLC4A5 was localized to the Golgi apparatus of cultured human RPE cells and in apical and basal membranes. Fundus imaging, optical coherence tomography, microscopy, and electroretinography (ERG) of tvrm77 mice revealed retinal detachment, hypopigmented patches corresponding to neovascular lesions, and retinal folds. Detachment worsened and outer nuclear layer thickness decreased with age. ERG a- and b-wave response amplitudes were initially normal but declined in older mice. The direct current ERG fast oscillation and light peak were reduced in amplitude at all ages, whereas other RPE-associated responses were unaffected. These results link a new Slc4a5 mutation to subretinal fluid accumulation and altered light-evoked RPE electrophysiological responses, suggesting that SLC4A5 functions at the outer blood-retinal barrier.

Inhibition of PIKfyve phosphoinositide kinase selectively kills autophagy-dependent cancer cells by disrupting lysosome homeostasis. Here, we show that PIKfyve inhibitors can also selectively eliminate pluripotent embryonal carcinoma cells (ECCs), embryonic stem cells, and induced pluripotent stem cells under conditions where differentiated cells remain viable. PIKfyve inhibitors prevented lysosome fission, induced autophagosome accumulation, and reduced cell proliferation in both pluripotent and differentiated cells, but they induced death only in pluripotent cells. The ability of PIKfyve inhibitors to distinguish between pluripotent and differentiated cells was confirmed with xenografts derived from ECCs. Pretreatment of ECCs with the PIKfyve specific inhibitor WX8 suppressed their ability to form teratocarcinomas in mice, and intraperitoneal injections of WX8 into mice harboring teratocarcinoma xenografts selectively eliminated pluripotent cells. Differentiated cells continued to proliferate, but at a reduced rate. These results provide a proof of principle that PIKfyve specific inhibitors can selectively eliminate pluripotent stem cells in vivo as well as in vitro., (Copyright © 2021. Published by Elsevier Inc.)

Pluripotent cells in the mammalian embryo undergo state transitions marked by changes in patterns of gene expression and developmental potential as they progress from pre-implantation through post-implantation stages of development. Recent studies of cultured mouse and human pluripotent stem cells (hPSCs) have identified cells representative of an intermediate stage (referred to as the formative state) between naive pluripotency (equivalent to pre-implantation epiblast) and primed pluripotency (equivalent to late post-implantation epiblast). We examine these recent findings in light of our knowledge of peri-implantation mouse and human development, and we consider the implications of this work for deriving human embryo models from pluripotent cells., Competing Interests: Declaration of interests M.F.P. and J.R. are members of the advisory board of Cell Stem Cell., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Objective: To quantify weekly rates of use of buprenorphine for those with employer-based insurance and whether the rate differs based on county-level measures of race, historical fatal drug overdose rate, and COVID-19 case rate., Methods: We used 2020 pharmaceutical claims for 4.8 million adults from a privately insured population to examine changes in the use of buprenorphine to treat opioid use disorder in 2020 during the onset of the COVID-19 pandemic. We quantified variation by examining changes in use rates across counties based on their fatal drug overdose rate in 2018, number of COVID-19 cases per capita, and percent nonwhite., Results: Weekly use of buprenorphine was relatively stable between the first week of January (0.6 per 10,000 enrollees, 95%CI = 0.2 to 1.1) and the last week of August (0.8 per 10,000 enrollees, 95%CI = 0.4 to 1.3). We did not find evidence of any consistent change in use of buprenorphine by county-level terciles for COVID-19 rate as of August 31, 2020, age-adjusted fatal drug overdose rate, and percent nonwhite. Use was consistently higher for counties in the highest tercile of county age-adjusted fatal drug overdose rate when compared to counties in the lowest tercile of county age-adjusted fatal drug overdose rate., Discussion: Our results provide early evidence that new federal- and state-level policies may have steadied the rate of using buprenorphine for those with employer-based insurance during the pandemic., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Introduction: The COVID-19 pandemic has forced telehealth to be the primary means through which patients interact with their providers. There is a concern that the pandemic will exacerbate the existing disparities in overall healthcare utilization and telehealth utilization. Few national studies have examined the changes in telehealth use during the COVID-19 pandemic., Methods: Data on 6.8 and 6.4 million employer-based health plan beneficiaries in 2020 and 2019, respectively, were collected in 2020. Unadjusted rates were compared both before and after the week of the declaration of the COVID-19 pandemic as a national emergency. Trends in weekly utilization were also examined using a difference-in-differences regression framework to quantify the changes in telemedicine and office-based care utilization while controlling for the patient's demographic and county-level sociodemographic measures. All analyses were conducted in 2020., Results: More than a 20-fold increase in the incidence of telemedicine utilization after March 13, 2020 was observed. Conversely, the incidence of office-based encounters declined by almost 50% and was not fully offset by the increase in telemedicine. The increase in telemedicine was greatest among patients in counties with low poverty levels (β=31.70, 95% CI=15.17, 48.23), among patients in metropolitan areas (β=40.60, 95% CI=30.86, 50.34), and among adults than among children aged 0-12 years (β=57.91, 95% CI=50.32, 65.49)., Conclusions: The COVID-19 pandemic has affected telehealth utilization disproportionately on the basis of patient age and both the county-level poverty rate and urbanicity., (Copyright © 2021 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.)

Nodal is a transforming growth factor-β (TGF-β) superfamily member that plays a number of critical roles in mammalian embryonic development. Nodal is essential for the support of the peri-implantation epiblast in the mouse embryo and subsequently acts to specify mesendodermal fate at the time of gastrulation and, later, left-right asymmetry. Maintenance of human pluripotent stem cells (hPSCs) in vitro is dependent on Nodal signaling. Because it has proven difficult to prepare a biologically active form of recombinant Nodal protein, Activin or TGFB1 are widely used as surrogates for NODAL in hPSC culture. Nonetheless, the expression of the components of an endogenous Nodal signaling pathway in hPSC provides a potential autocrine pathway for the regulation of self-renewal in this system. Here we review recent studies that have clarified the role of Nodal signaling in pluripotent stem cell populations, highlighted spatial restrictions on Nodal signaling, and shown that Nodal functions in vivo as a heterodimer with GDF3, another TGF-β superfamily member expressed by hPSC. We discuss the role of this pathway in the maintenance of the epiblast and hPSC in light of these new advances., (© 2021 AlphaMed Press.)

Traumatic brain injury (TBI) is one of the leading causes of death among young people, and is increasingly prevalent in the aging population. Survivors of TBI face a spectrum of outcomes from short-term non-incapacitating injuries to long-lasting serious and deteriorating sequelae. TBI is a highly complex condition to treat; many variables can account for the observed heterogeneity in patient outcome. The limited success of neuroprotection strategies in the clinic has led to a new emphasis on neurorestorative approaches. In TBI, it is well recognized clinically that patients with similar lesions, age, and health status often display differences in recovery of function after injury. Despite this heterogeneity of outcomes in TBI, restorative treatment has remained generic. There is now a new emphasis on developing a personalized medicine approach in TBI, and this will require an improved understanding of how genetics impacts on long-term outcomes. Studies in animal model systems indicate clearly that the genetic background plays a role in determining the extent of recovery following an insult. A candidate gene approach in human studies has led to the identification of factors that can influence recovery. Here we review studies of the genetic basis for individual differences in functional recovery in the CNS in animals and man. The application of in vitro modeling with human cells and organoid cultures, along with whole-organism studies, will help to identify genes and networks that account for individual variation in recovery from brain injury, and will point the way towards the development of new therapeutic approaches.

Objectives: To evaluate the prevalence of social determinants of health (SDoH) factors in a large commercially-insured population and to characterize the prevalence of common conditions (eg, diabetes, behavioral health issues) and addressable health services utilization concerns (eg, lack of preventive care) for which employers offer no- and low-cost benefit programs., Methods: We identified groups with SDoH challenges within a commercially-insured population of 5.1 M through administrative data and self-report. Using medical claims and health assessment data, we identified populations with SDoH needs who had common conditions for which employers often provide no- or low-cost benefit programs (ie, diabetes, behavioral health conditions, high-risk pregnancy, overweight/obesity). Additionally, we sought populations with common addressable health services utilization concerns such as avoidable emergency room visits, lack of preventive care services, or non-adherence to medications. We used univariate analyses to describe the prevalence of SDoH risks in the population of interest., Results: Twenty-seven percent of this commercially-insured population live in a zip code where the median income is at or below 200% of the Federal Poverty Line. Respondents identified cost (55%) and family, school, or work responsibilities (26%) as key barriers to care. ER overutilization rates are higher in lower income zip codes than wealthier zip codes (34% vs 9%) as is the prevalence of diabetes, overweight/obesity, and behavioral issues, and decreased use of preventive services. Fifteen percent of the study population live in a low-access food area. There is considerable variability in access to employer-sponsored resources to address these needs (70% of employers provide behavioral health programs; 63% provide telehealth programs, but only 1% offer healthy food programs and less than 0.5% offer either child care or transportation support programs)., Conclusions: Commercially insured populations could benefit from employer-sponsored programs or benefits that address key SDoH barriers such as financial support, healthy food programs, child-care, and transportation.

Importance: The coronavirus disease 2019 (COVID-19) pandemic has placed unprecedented strain on patients and health care professionals and institutions, but the association of the pandemic with use of preventive, elective, and nonelective care, as well as potential disparities in use of health care, remain unknown., Objective: To examine changes in health care use during the first 2 months of the COVID-19 pandemic in March and April of 2020 relative to March and April of 2019 and 2018, and to examine whether changes in use differ by patient's zip code-level race/ethnicity or income., Design, Setting, and Participants: This cross-sectional study analyzed health insurance claims for patients from all 50 US states who receive health insurance through their employers. Changes in use of preventive services, nonelective care, elective procedures, prescription drugs, in-person office visits, and telemedicine visits were examined during the first 2 months of the COVID-19 pandemic in 2020 relative to existing trends in 2019 and 2018. Disparities in the association of the pandemic with health care use based on patient's zip code-level race and income were also examined., Results: Data from 5.6, 6.4, and 6.8 million US individuals with employer-sponsored insurance in 2018, 2019, and 2020, respectively, were analyzed. Patient demographics were similar in all 3 years (mean [SD] age, 34.3 [18.6] years in 2018, 34.3 [18.5] years in 2019, and 34.5 [18.5] years in 2020); 50.0% women in 2018, 49.5% women in 2019, and 49.5% women in 2020). In March and April 2020, regression-adjusted use rate per 10 000 persons changed by -28.2 (95% CI, -30.5 to -25.9) and -64.5 (95% CI, -66.8 to -62.2) for colonoscopies; -149.1 (95% CI, -162.0 to -16.2) and -342.1 (95% CI, -355.0 to -329.2) for mammograms; -60.0 (95% CI, -63.3 to -54.7) and -118.1 (95% CI, -112.4 to -113.9) for hemoglobin A1c tests; -300.5 (95% CI, -346.5 to -254.5) and -369.0 (95% CI, -414.7 to -323.4) for child vaccines; -4.6 (95% CI, -5.3 to -3.9) and -10.9 (95% CI, -11.6 to -10.2) for musculoskeletal surgery; -1.1 (95% CI, -1.4 to -0.7) and -3.4 (95% CI, -3.8 to -3.0) for cataract surgery; -13.4 (95% CI, -14.6 to -12.2) and -31.4 (95% CI, -32.6 to -30.2) for magnetic resonance imaging; and -581.1 (95% CI, -612.9 to -549.3) and -1465 (95% CI, -1496 to -1433) for in-person office visits. Use of telemedicine services increased by 227.9 (95% CI, 221.7 to 234.1) per 10 000 persons and 641.6 (95% CI, 635.5 to 647.8) per 10 000 persons. Patients living in zip codes with lower-income or majority racial/ethnic minority populations experienced smaller reductions in in-person visits (≥80% racial/ethnic minority zip code: 200.0 per 10 000 [95% CI, 128.9-270.1]; 79%-21% racial/ethnic minority zip code: 54.2 per 10 000 [95% CI, 33.6-74.9]) but also had lower rates of adoption of telemedicine (≥80% racial/ethnic minority zip code: -71.6 per 10 000 [95% CI, -87.6 to -55.5]; 79%-21% racial/ethnic minority zip code: -15.1 per 10 000 [95% CI, -19.8 to -10.4])., Conclusions and Relevance: In this cross-sectional study of a large US population with employer-sponsored insurance, the first 2 months of the COVID-19 pandemic were associated with dramatic reductions in the use of preventive and elective care. Use of telemedicine increased rapidly but not enough to account for reductions in in-person primary care visits. Race and income disparities at the zip code level exist in use of telemedicine.

Archetypal human pluripotent stem cells (hPSC) are widely considered to be equivalent in developmental status to mouse epiblast stem cells, which correspond to pluripotent cells at a late post-implantation stage of embryogenesis. Heterogeneity within hPSC cultures complicates this interspecies comparison. Here we show that a subpopulation of archetypal hPSC enriched for high self-renewal capacity (ESR) has distinct properties relative to the bulk of the population, including a cell cycle with a very low G1 fraction and a metabolomic profile that reflects a combination of oxidative phosphorylation and glycolysis. ESR cells are pluripotent and capable of differentiation into primordial germ cell-like cells. Global DNA methylation levels in the ESR subpopulation are lower than those in mouse epiblast stem cells. Chromatin accessibility analysis revealed a unique set of open chromatin sites in ESR cells. RNA-seq at the subpopulation and single cell levels shows that, unlike mouse epiblast stem cells, the ESR subset of hPSC displays no lineage priming, and that it can be clearly distinguished from gastrulating and extraembryonic cell populations in the primate embryo. ESR hPSC correspond to an earlier stage of post-implantation development than mouse epiblast stem cells.

Over the past few years, a number of research groups have reported striking progress on the generation of in vitro models from mouse and human stem cells that replicate aspects of early embryonic development. Not only do these models reproduce some key cell fate decisions but, especially in the mouse system, they also mimic the spatiotemporal arrangements of embryonic and extraembryonic tissues that are required for developmental patterning and implantation in the uterus. If such models could be developed for the early human embryo, they would have great potential benefits for understanding early human development, for biomedical science, and for reducing the use of animals and human embryos in research. However, guidelines for the ethical conduct of this line of work are at present not well defined. In this Forum article, we discuss some key aspects of this emerging area of research and provide some recommendations for its ethical oversight., (Copyright © 2019 The Authors. Published by Elsevier Inc. All rights reserved.)

Stem Cell Reports frequently receives manuscripts dealing with the topic of cancer stem cells. Many of the submissions on this topic have major shortcomings in their content or limits to the conclusions that can be drawn from the results presented. The purpose of this Commentary is to highlight some of the underlying issues so that authors can enhance the strength of their research contributions., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Objectives: We conducted a study of the food environment and nutritional status among women and children living on a Galapagos Island. Anthropometric and body silhouette data give insight into body size perceptions for women and their young children. We frame our findings in the context of the nutrition transition., Methods: A convenience sample was recruited via word-of-mouth for in-depth interviews and assessments of household food security, dietary intake, anthropometrics, and body image. Interviews took place in 2011 on San Cristobal Island, one of four inhabited islands in the Galapagos archipelago. Twenty women with children between the ages of one and six participated, all permanent residents of San Cristobal Island., Results: Most women (60%) reported limited availability of fresh produce due to an unreliable food supply shipped from mainland Ecuador. Despite reported food insecurity in our sample (55%), more than half of the children (55%) experienced high dietary diversity measured by 24 h recall. Women tended to report less dietary diversity than their children, which may be linked to a stated desire to be thinner. Eighty percent of children were classified as normal weight, while 75% of women were overweight or obese. Conclusions for Practice: Results provide an initial survey of the food landscape on one Galapagos Island. By combining qualitative interviews with indicators of nutritional status, the narrative data allow an interpretation of issues of food security, dietary intakes, dietary diversity, and body size. This study forms the basis for a larger examination of these issues in the Galapagos islands.

The Sialyl Lewis A antigen, or CA 19-9, is the prototype serum biomarker for adenocarcinoma of the pancreas. Despite extensive clinical study of CA 19-9 in gastrointestinal malignancies, surprisingly little is known concerning the specific cell types that express this marker during development, tissue regeneration and neoplasia. SOX9 is a transcription factor that plays a key role in these processes in foregut tissues. We report the biochemistry and tissue expression of the GCTM-5 antigen, a pancreatic cancer marker related to, but distinct from, CA19-9. This antigen, defined by two monoclonal antibodies recognising separate epitopes on a large glycoconjugate protein complex, is co-expressed with SOX9 by foregut ductal progenitors in the developing human liver and pancreas, and in pancreatic adenocarcinoma. These progenitors are distinct from cell populations identified by DCLK1, LGR5, or canonical markers of liver and pancreatic progenitor cells. Co-expression of this antigen complex and SOX9 also characterises the ductal metaplasia of submucosal glands that occurs during the development of Barrett's oesophagus. The GCTM-5 antigen complex can be detected in the sera of patients with pancreatic adenocarcinoma. The GCTM-5 epitope shows a much more restricted pattern of expression in the normal adult pancreas relative to CA19-9. Our findings will aid in the identification, characterisation, and monitoring of ductal progenitor cells during development and progression of pancreatic adenocarcinoma in man.

Minority subpopulations within embryonic stem cell cultures display an expanded developmental potential similar to that of early embryo blastomeres or the early inner cell mass. The ability to isolate and culture totipotent cells capable of giving rise to the entire conceptus would enhance our capacity to study early embryo development, and might enable more efficient generation of chimeric animals for research and organ production for transplantation. Here we review the biological and molecular characterization of cultured cells with developmental potential similar to totipotent blastomeres, and assess recent progress toward the capture and stabilization of the totipotent state in vitro., (Copyright © 2017. Published by Elsevier Inc.)

Human embryonic stem cells (hESCs) have historically been cultivated on feeder layers of primary mouse embryonic fibroblasts (MEF) in a medium supplemented with fetal calf serum (FCS). However, serum contains a wide variety of biologically active compounds that might adversely affect hESC growth and differentiation. Thus, cultivation of stem cells in FCS complicates experimental approaches to define the intracellular mechanisms required for hESC maintenance. This chapter describes the serum-free maintenance of hESCs in culture by addition of sphingosine-1-phosphate (S1P) and platelet-derived growth factor (PDGF). This complete protocol provides a simple alternative chemically defined serum-free system that is relatively inexpensive and advantageous for studying signaling pathways involved in hESC pluripotency.

Background: Stem cells-derived neuronal cultures hold great promise for in vitro disease modelling and drug screening. However, currently stem cells-derived neuronal cultures do not recapitulate the functional properties of primary neurons, such as network properties. Cultured primary murine neurons develop networks which are synchronised over large fractions of the culture, whereas neurons derived from mouse embryonic stem cells (ESCs) display only partly synchronised network activity and human pluripotent stem cells-derived neurons have mostly asynchronous network properties. Therefore, strategies to improve correspondence of derived neuronal cultures with primary neurons need to be developed to validate the use of stem cell-derived neuronal cultures as in vitro models., New Method: By combining serum-free derivation of ESCs from mouse blastocysts with neuronal differentiation of ESCs in morphogen-free adherent culture we generated neuronal networks with properties recapitulating those of mature primary cortical cultures., Results: After 35days of differentiation ESC-derived neurons developed network activity very similar to that of mature primary cortical neurons. Importantly, ESC plating density was critical for network development., Comparison With Existing Method(s): Compared to the previously published methods this protocol generated more synchronous neuronal networks, with high similarity to the networks formed in mature primary cortical culture., Conclusion: We have demonstrated that ESC-derived neuronal networks recapitulating key properties of mature primary cortical networks can be generated by optimising both stem cell derivation and differentiation. This validates the approach of using ESC-derived neuronal cultures for disease modelling and in vitro drug screening., (Copyright © 2017 Elsevier B.V. All rights reserved.)

This corrects the article DOI: 10.1038/nbt.4015.

In many jurisdictions, restrictions prohibit the culture of human embryos beyond 14 days of development. However, recent reports describing the successful maintenance of embryos in vitro to this stage have prompted many in the field to question whether the rule is still appropriate. This Spotlight article looks at the original rationale behind the 14-day rule and its relevance today in light of advances in human embryo culture and in the derivation of embryonic-like structures from human pluripotent stem cells., Competing Interests: Competing interestsThe author declares no competing or financial interests., (© 2017. Published by The Company of Biologists Ltd.)

We sought to identify the impacts of Friedreich's ataxia (FRDA) on cardiomyocytes. FRDA is an autosomal recessive degenerative condition with neuronal and non-neuronal manifestations, the latter including progressive cardiomyopathy of the left ventricle, the leading cause of death in FRDA. Little is known about the cellular pathogenesis of FRDA in cardiomyocytes. Induced pluripotent stem cells (iPSCs) were derived from three FRDA individuals with characterized GAA repeats. The cells were differentiated into cardiomyocytes to assess phenotypes. FRDA iPSC- cardiomyocytes retained low levels of FRATAXIN (FXN) mRNA and protein. Electrophysiology revealed an increased variation of FRDA- cardiomyocyte beating rates which was prevented by addition of nifedipine, suggestive of a calcium handling deficiency. Finally, calcium imaging was performed and we identified small amplitude, diastolic and systolic calcium transients confirming a deficiency in calcium handling. We defined a robust FRDA cardiac-specific electrophysiological profile in patient-derived iPSCs which could be used for high throughput compound screening. This cell-specific signature will contribute to the identification and screening of novel treatments for this life-threatening disease.

Unlabelled: Our current understanding of the induction of pluripotency by defined factors indicates that this process occurs in discrete stages characterized by specific alterations in the cellular transcriptome and epigenome. However, the final phase of the reprogramming process is incompletely understood. We sought to generate tools to characterize the transition to a fully reprogramed state. We used combinations of stem cell surface markers to isolate colonies emerging after transfection of human fibroblasts with reprogramming factors and then analyzed their expression of genes associated with pluripotency and early germ lineage specification. We found that expression of a subset of these genes, including the cell-cell adhesion molecule CDH3, characterized a late stage in the reprogramming process. Combined live-cell staining with the antibody GCTM-2 and anti-CDH3 during reprogramming identified colonies of cells that showed gene expression patterns very similar to those of embryonic stem cell or established induced pluripotent stem cell lines, and gave rise to stable induced pluripotent stem cell lines at high frequency. Our findings will facilitate studies of the final stages of reprogramming of human cells to pluripotency and will provide a simple means for prospective identification of fully reprogrammed cells., Significance: Reprogramming of differentiated cells back to an embryonic pluripotent state has wide ranging applications in understanding and treating human disease. However, how cells traverse the barriers on the journey to pluripotency still is not fully understood. This report describes tools to study the late stages of cellular reprogramming. The findings enable a more precise approach to dissecting the final phases of conversion to pluripotency, a process that is particularly poorly defined. The results of this study also provide a simple new method for the selection of fully reprogrammed cells, which could enhance the efficiency of derivation of cell lines for research and therapy., (©AlphaMed Press.)

Friedreich ataxia (FRDA) is the most common of the inherited ataxias. It is an autosomal recessive disease characterised by degeneration of peripheral sensory neurons, regions of the central nervous system and cardiomyopathy. FRDA is usually due to homozygosity for trinucleotide GAA repeat expansions found within first intron of the FRATAXIN (FXN) gene, which results in reduced levels of the mitochondrial protein FXN. Reduced FXN protein results in mitochondrial dysfunction and iron accumulation leading to increased oxidative stress and cell death in the nervous system and heart. Yet the precise functions of FXN and the underlying mechanisms leading to disease pathology remain elusive. This is particularly true of the cardiac aspect of FRDA, which remains largely uncharacterized at the cellular level. Here, we summarise current knowledge on experimental models in which to study FRDA cardiomyopathy, with a particular focus on the use of human pluripotent stem cells as a disease model., (Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.)

Recent studies show that pluripotent stem cells can undergo self-organized development in vitro into structures that mimic the body plan of the post-implantation embryo. Modeling human embryogenesis in a dish opens up new possibilities for the study of early development and developmental disorders, but it may also raise substantial ethical concerns.

In the mouse, naïve pluripotent stem cells (PSCs) are thought to represent the cell culture equivalent of the late epiblast in the pre-implantation embryo, with which they share a unique defining set of features. Recent studies have focused on the identification and propagation of a similar cell state in human. Although the capture of an exact human equivalent of the mouse naïve PSC remains an elusive goal, comparative studies spurred on by this quest are lighting the path to a deeper understanding of pluripotent state regulation in early mammalian development., (© 2015. Published by The Company of Biologists Ltd.)

We assessed structural elements of the retina in individuals with Friedreich ataxia (FRDA) and in mouse models of FRDA, as well as functions of the retinal pigment epithelium (RPE) in FRDA using induced pluripotent stem cells (iPSCs). We analyzed the retina of the FRDA mouse models YG22R and YG8R containing a human FRATAXIN (FXN) transgene by histology. We complemented this work with post-mortem evaluation of eyes from FRDA patients. Finally, we derived RPE cells from patient FRDA-iPSCs to assess oxidative phosphorylation (OXPHOS) and phagocytosis. We showed that whilst the YG22R and YG8R mouse models display elements of retinal degeneration, they do not recapitulate the loss of retinal ganglion cells (RGCs) found in the human disease. Further, RPE cells differentiated from human FRDA-iPSCs showed normal OXPHOS and we did not observe functional impairment of the RPE in Humans.

The caudal neural plate is a distinct region of the embryo that gives rise to major progenitor lineages of the developing central and peripheral nervous system, including neural crest and floor plate cells. We show that dual inhibition of the glycogen synthase kinase 3β and activin/nodal pathways by small molecules differentiate human pluripotent stem cells (hPSCs) directly into a preneuroepithelial progenitor population we named "caudal neural progenitors" (CNPs). CNPs coexpress caudal neural plate and mesoderm markers, and, share high similarities to embryonic caudal neural plate cells in their lineage differentiation potential. Exposure of CNPs to BMP2/4, sonic hedgehog, or FGF2 signaling efficiently directs their fate to neural crest/roof plate cells, floor plate cells, and caudally specified neuroepithelial cells, respectively. Neural crest derived from CNPs differentiated to neural crest derivatives and demonstrated extensive migratory properties in vivo. Importantly, we also determined the key extrinsic factors specifying CNPs from human embryonic stem cell include FGF8, canonical WNT, and IGF1. Our studies are the first to identify a multipotent neural progenitor derived from hPSCs, that is the precursor for major neural lineages of the embryonic caudal neural tube., (© 2015 AlphaMed Press.)

Devising a cell culture method that maintains human pluripotent stem cells (PSCs) in a state similar to naive mouse embryonic stem cells (ESCs) has been a much sought after goal in recent years. Here I consider the historical background to this quest and ask why it is considered consequential., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Heterogeneity is a hallmark of stem cell populations, in part due to the molecular differences between cells undergoing self-renewal and those poised to differentiate. We examined phenotypic and molecular heterogeneity in pluripotent stem cell populations, using public gene expression data sets. A high degree of concordance was observed between global gene expression variability and the reported heterogeneity of different human pluripotent lines. Network analysis demonstrated that low-variability genes were the most highly connected, suggesting that these are the most stable elements of the gene regulatory network and are under the highest regulatory constraints. Known drivers of pluripotency were among these, with lowest expression variability of POU5F1 in cells with the highest capacity for self-renewal. Variability of gene expression provides a reliable measure of phenotypic and molecular heterogeneity and predicts those genes with the highest degree of regulatory constraint within the pluripotency network., (Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.)

Age-related macular degeneration (AMD) is a leading cause of severe vision loss in the Western world and is increasing exponentially as the population ages. Despite enormous worldwide efforts, the earliest pathogenic pathways involved in AMD are still not fully understood. It is essential to develop research tools for effective modeling of AMD pathogenesis and for subsequent drug discovery and cell or molecular therapies. This review will focus on the current progress in human pluripotent stem cells for understanding and treating AMD.

Pluripotent stem cells display significant heterogeneity in gene expression, but whether this diversity is an inherent feature of the pluripotent state remains unknown. Single-cell gene expression analysis in cell subsets defined by surface antigen expression revealed that human embryonic stem cell cultures exist as a continuum of cell states, even under defined conditions that drive self-renewal. The majority of the population expressed canonical pluripotency transcription factors and could differentiate into derivatives of all three germ layers. A minority subpopulation of cells displayed high self-renewal capacity, consistently high transcripts for all pluripotency-related genes studied, and no lineage priming. This subpopulation was characterized by its expression of a particular set of intercellular signaling molecules whose genes shared common regulatory features. Our data support a model of an inherently metastable self-renewing population that gives rise to a continuum of intermediate pluripotent states, which ultimately become primed for lineage specification.

Two recent papers in Nature describe a remarkable new technique for reprogramming somatic cells back to the embryonic state. Obokata et al. (2014a, 2014b) show that applying stressful stimuli can convert mature cells into progenitors capable of generating all three embryonic germ layer lineages, as well as placental tissue., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Human embryonic stem cells (hESCs) regularly acquire nonrandom genomic aberrations during culture, raising concerns about their safe therapeutic application. The International Stem Cell Initiative identified a copy number variant (CNV) amplification of chromosome 20q11.21 in 25% of hESC lines displaying a normal karyotype. By comparing four cell lines paired for the presence or absence of this CNV, we show that those containing this amplicon have higher population doubling rates, attributable to enhanced cell survival through resistance to apoptosis. Of the three genes encoded within the minimal amplicon and expressed in hESCs, only overexpression of BCL2L1 (BCL-XL isoform) provides control cells with growth characteristics similar to those of CNV-containing cells, whereas inhibition of BCL-XL suppresses the growth advantage of CNV cells, establishing BCL2L1 as a driver mutation. Amplification of the 20q11.21 region is also detectable in human embryonal carcinoma cell lines and some teratocarcinomas, linking this mutation with malignant transformation.