Two decades of embryonic stem cells : a historical overview

STUDY QUESTION How did the field of stem cell research develop in the years following the derivation of the first human embryonic stem cell (hESC) line? SUMMARY ANSWER Supported by the increasing number of clinical trials to date, significant technological advances in the past two decades have brought us ever closer to clinical therapies derived from pluripotent cells. WHAT IS KNOWN ALREADY Since their discovery 20 years ago, the use of human pluripotent stem cells has progressed tremendously from bench to bedside. Here, we provide a concise review of the main keystones of this journey and focus on ongoing clinical trials, while indicating the most relevant future research directions. STUDY DESIGN, SIZE, DURATION This is a historical narrative, including relevant publications in the field of pluripotent stem cells (PSC) derivation and differentiation, recounted both through scholarly research of published evidence and interviews of six pioneers who participated in some of the most relevant discoveries in the field. PARTICIPANTS/MATERIALS, SETTING, METHODS The authors all contributed by researching the literature and agreed upon body of works. Portions of the interviews of the field pioneers have been integrated into the review and have also been included in full for advanced reader interest. MAIN RESULTS AND THE ROLE OF CHANCE The stem cell field is ever expanding. We find that in the 20 years since the derivation of the first hESC lines, several relevant developments have shaped the pluripotent cell field, from the discovery of different states of pluripotency, the derivation of induced PSC, the refinement of differentiation protocols with several clinical trials underway, as well as the recent development of organoids. The challenge for the years to come will be to validate and refine PSCs for clinical use, from the production of highly defined cell populations in clinical grade conditions to the possibility of creating replacement organoids for functional, if not anatomical, function restoration. LIMITATIONS, REASONS FOR CAUTION This is a non-systematic review of current literature. Some references may have escaped the experts’ analysis due to the exceedingly diverse nature of the field. As the field of regenerative medicine is rapidly advancing, some of the most recent developments may have not been captured entirely. WIDER IMPLICATIONS OF THE FINDINGS The multi-disciplinary nature and tremendous potential of the stem cell field has important implications for basic as well as translational research. Recounting these activities will serve to provide an in-depth overview of the field, fostering a further understanding of human stem cell and developmental biology. The comprehensive overview of clinical trials and expert opinions included in this narrative may serve as a valuable scientific resource, supporting future efforts in translational approaches. STUDY FUNDING/COMPETING INTEREST(S) ESHRE provided funding for the authors’ on-site meeting and discussion during the preparation of this manuscript. S.M.C.S.L. is funded by the European Research Council Consolidator (ERC-CoG-725722-OVOGROWTH). M.P. is supported by the Special Research Fund, Bijzonder Onderzoeksfonds (BOF01D08114). M.G. is supported by the Methusalem grant of Vrije Universiteit Brussel, in the name of Prof. Karen Sermon and by Innovation by Science and Technology in Flanders (IWT, Project Number: 150042). A.V. and B.A. are supported by the Plataforma de Proteomica, Genotipado y Líneas Celulares (PT1770019/0015) (PRB3), Instituto de Salud Carlos III. Research grant to B.H. by the Research Foundation—Flanders (FWO) (FWO.KAN.2016.0005.01 and FWO.Project G051516N). There are no conflicts of interest to declare. TRIAL REGISTRATION NUMBER Not applicable. ESHRE Pages are not externally peer reviewed. This article has been approved by the Executive Committee of ESHRE

A Comparative Study of Cell Culture Conditions during Conversion from Primed to Naive Human Pluripotent Stem Cells

The successful reprogramming of human somatic cells into induced pluripotent stem cells (hiPSCs) represented a turning point in the stem cell research field, owing to their ability to differentiate into any cell type with fewer ethical issues than human embryonic stem cells (hESCs). In mice, PSCs are thought to exist in a naive state, the cell culture equivalent of the immature pre-implantation embryo, whereas in humans, PSCs are in a primed state, which is a more committed pluripotent state than a naive state. Recent studies have focused on capturing a similar cell stage in human cells. Given their earlier developmental stage and therefore lack of cell-of-origin epigenetic memory, these cells would be better candidates for further re-differentiation, use in disease modeling, regenerative medicine and drug discovery. In this study, we used primed hiPSCs and hESCs to evaluate the successful establishment and maintenance of a naive cell stage using three different naive-conversion media, both in the feeder and feeder-free cells conditions. In addition, we compared the directed differentiation capacity of primed and naive cells into the three germ layers and characterized these different cell stages with commonly used pluripotent and lineage-specific markers. Our results show that, in general, naive culture NHSM medium (in both feeder and feeder-free systems) confers greater hiPSCs and hESCs viability and the highest naive pluripotency markers expression. This medium also allows better cell differentiation cells toward endoderm and mesoderm.This work was supported by the Health Department of the Basque Government (Grant 2019111068, 2019/4703, 2020111058, 2020333032, 2021333057 and 2021333012), Merck-Salud Founda- tion (FSALUD17/004), Economic Development and Infrastructures Department of the Basque Govern- ment (KK-2020/00068), EITB Maratoia (BIO21/COV/030), Project “PI18/01299” and “PI21/01187”, funded by Instituto de Salud Carlos III and co-funded by European Union (ERDF) “A way to make Europe”, “ICI21/00095” funded by Instituto de Salud Carlos III and co-funded by European Union (NextGenerationEU), “Plan de Recuperación Transformación y Resiliencia” Investigación Clínica Independiente 2021–Acción Estratégica Salud 2017–2020, RICORS: (RD21/00017/0024) Red Española de Terapias Avanzadas TERAV ISCIII. Funded by Instituto de Salud Carlos III (ISCIII) and co-funded by European Union (NextGenerationEU) “Plan de Recuperación Transformación y Resiliencia” Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) 2021–Acción Estratégica Salud 2017–2020. L.H. was supported by the Jesus Gangoiti Barrera Foundation and the Asociación Española contra el Cáncer (AECC) AECC16/501 and the Fundación Mutua Madrileña AP176182020. M.M-I was supported by Jesus Gangoiti Barrera Foundation. I.R was supported by Margarita Salas Grant “MARSA21/60” and the Jesus Gangoiti Barrera Foundation. M.I-F. was supported by Inocente Inocente Foundation FII18/003. J.R.P. has grant “RYC-2013-13450” funded by MCIN/AEI/10.13039/501100011033, by the European Social Fund “ESF investing in your future”

Identifying SARS-CoV-2 'memory' NK cells from COVID-19 convalescent donors for adoptive cell therapy

COVID-19 disease is the manifestation of syndrome coronavirus 2 (SARS-CoV-2) infection, which is causing a worldwide pandemic. This disease can lead to multiple and different symptoms, being lymphopenia associated with severity one of the most persistent. Natural killer cells (NK cells) are part of the innate immune system, being fighting against virus-infected cells one of their key roles. In this study, we determined the phenotype of NK cells after COVID-19 and the main characteristic of SARS-CoV-2-specific-like NK population in the blood of convalescent donors. CD57+ NKG2C+ phenotype in SARS-CoV-2 convalescent donors indicates the presence of 'memory'/activated NK cells as it has been shown for cytomegalovirus infections. Although the existence of this population is donor dependent, its expression may be crucial for the specific response against SARS-CoV-2, so that, it gives us a tool for selecting the best donors to produce off-the-shelf living drug for cell therapy to treat COVID-19 patients under the RELEASE clinical trial (NCT04578210)

Cell-cell interactions during the formation of primordial follicles in humans

Gametogenesis is a complex and sex-specific multistep process during which the gonadal somatic niche plays an essential regulatory role. One of the most crucial steps during human female gametogenesis is the formation of primordial follicles, the functional unit of the ovary that constitutes the pool of follicles available at birth during the entire reproductive life. However, the relation between human fetal germ cells (hFGCs) and gonadal somatic cells during the formation of the primordial follicles remains largely unexplored. We have discovered that hFGCs can form multinucleated syncytia, some connected via interconnecting intercellular bridges, and that not all nuclei in hFGC-syncytia were synchronous regarding meiotic stage. As hFGCs progressed in development, pre-granulosa cells formed protrusions that seemed to progressively constrict individual hFGCs, perhaps contributing to separate them from the multinucleated syncytia. Our findings highlighted the cell-cell interaction and molecular dynamics between hFGCs and (pre)granulosa cells during the formation of primordial follicles in humans. Knowledge on how the pool of primordial follicle is formed is important to understand human infertility.</p

Treatment with tocilizumab or corticosteroids for COVID-19 patients with hyperinflammatory state: a multicentre cohort study (SAM-COVID-19)

Objectives: The objective of this study was to estimate the association between tocilizumab or corticosteroids and the risk of intubation or death in patients with coronavirus disease 19 (COVID-19) with a hyperinflammatory state according to clinical and laboratory parameters. Methods: A cohort study was performed in 60 Spanish hospitals including 778 patients with COVID-19 and clinical and laboratory data indicative of a hyperinflammatory state. Treatment was mainly with tocilizumab, an intermediate-high dose of corticosteroids (IHDC), a pulse dose of corticosteroids (PDC), combination therapy, or no treatment. Primary outcome was intubation or death; follow-up was 21 days. Propensity score-adjusted estimations using Cox regression (logistic regression if needed) were calculated. Propensity scores were used as confounders, matching variables and for the inverse probability of treatment weights (IPTWs). Results: In all, 88, 117, 78 and 151 patients treated with tocilizumab, IHDC, PDC, and combination therapy, respectively, were compared with 344 untreated patients. The primary endpoint occurred in 10 (11.4%), 27 (23.1%), 12 (15.4%), 40 (25.6%) and 69 (21.1%), respectively. The IPTW-based hazard ratios (odds ratio for combination therapy) for the primary endpoint were 0.32 (95%CI 0.22-0.47; p < 0.001) for tocilizumab, 0.82 (0.71-1.30; p 0.82) for IHDC, 0.61 (0.43-0.86; p 0.006) for PDC, and 1.17 (0.86-1.58; p 0.30) for combination therapy. Other applications of the propensity score provided similar results, but were not significant for PDC. Tocilizumab was also associated with lower hazard of death alone in IPTW analysis (0.07; 0.02-0.17; p < 0.001). Conclusions: Tocilizumab might be useful in COVID-19 patients with a hyperinflammatory state and should be prioritized for randomized trials in this situatio

El conflicto Este-Oeste y la crisis centroamericana

Este artículo se dedica a analizar el contexto externo -marcado por el conflicto EE.UU.-URSS- en el que se desenvuelve la actual crisis político-militar de los países centroamericanos, con el fin de reflexionar acerca de la amenazada hegemonía estadounidense y la reciente entrada de la Unión Soviética en el juego geopolítico regional. Para ello se hace un recuento histórico de las relaciones entre EE.UU. y Centroamérica, y de la evolución de la política exterior de la URSS hacia el Tercer Mundo; se analizan también las condiciones políticas internas de EE.UU., de la URSS y de los países centroamericanos, que han marcado el tono de la relaciones entre ambas potencias y la región centroamericana. El artículo concluye sugiriendo que la actual coyuntura, en la que las condiciones de la política interna estadounidense parecen abrirle espacio a la negociación de la paz y la influencia de la URSS sobre la región parece relativizarse, ha generado posibilidades de maniobra para los gobiernos centroamericanos que, sin embargo, y a falta de voluntad política, no están siendo aprovechadas

De contadora a Esquipulas: Washington y Centroamérica en un mundo cambiante

La política exterior de Estados Unidos ha tenido siempre una incidencia importante en el acontecer político y económico de los pequeños países del istmo centroamericano. Debido a la profunda asimetría en las relación y a la multiplicidad de las vinculaciones, el impacto de las acciones del gran país del Norte (o de la ausencia de ellas) es tal, que quiéralo o no, las políticas norteamericanas continuaran influenciando fuertemente el desarrollo de todos los aspectos relevantes en las sociedades centroamericanas. Ahora bien, el gobierno de los Estados Unidos no puede prever y mucho menos controlar el proceso resultante de la interacción entre sus acciones y las dinámicas internas de cada sistema político en  la región

Política exterior y procesos de decisión en Centroamérica: elementos para una aproximación a los procesos de negociación regional

Política exterior y procesos de decisión Centro America. En la ultima década se han multiplicado los actores nacionales e internacionales que inciden y condicionan la política exterior de los países centroamericanos. En esta década de crisis regional, los procesos de negociación han sido tan intensos como los enfrentamientos armados. ¿Cómo se han tornado las decisiones?, ¿Quiénes han participado?, ¿Cuáles han sido los principales factores que influyen?. Estas son algunas de las preguntas que se busca responder en el trabajo. Para ello se considera el condicionamiento estructural que impone el contexto externo y el contexto interno. El proceso de articulación de la decisión es analizado en tres fases distintas: la fase del debate, la fase de la articulación política, y la fase de la operacionalización burocrática. Para cada una de estas fases se definen las variables claves. que permiten establecer tanto comparaciones regionales como al interior de un mismo país. En cada caso, ya sea que se trate de los condicionamientos estructurales o de las fases del proceso, se desarrollan ejemplos que ilustran las afirmaciones sobre la base de alguno de los procesos de negociación emprendidos en el área centroamericana