Expanding the Boundaries of Embryonic Stem Cells

The boundaries of embryonic stem cell (ESC) research have extended considerably in recent years in several important ways. Alongside a deeper understanding of the pluripotent state, ESCs have been successfully integrated into various fields, such as genomics, epigenetics, and disease modeling. Significant progress in cell fate control has pushed directed differentiation and tissue engineering further than ever before and promoted clinical trials. The geographical distribution of research activity has also expanded, especially for human ESCs. This review outlines these developments and future challenges that remain

Rentabilidad inicial y anual en ofertas públicas de activos en Israel durante los años 1998-2006

Contrary to findings reported in the extant IPO literature between 2001 and 2006, average first-day returns in Israel’s stock market resulted in a deficit return of −1.2% and the average one-year return resulted in an excess return of 10.5%. Estimating the relationship between yields and various explanatory variables, we found that daily yield is positively affected by excess demand and total equity capital, whilst negatively correlated with underwriting commissions, price of offerings and the total sum raised. The one-year return was found to be positively correlated with deficient underwriting and negatively correlated with first-day return and return on capitalContrariamente a las conclusiones halladas en la literatura existente sobre las Ofertas Públicas Iniciales entre 2001 y 2006, el promedio de rentabilidad el primer día en la Bolsa de Valores de Israel resultó en un déficit de −1,2%, mientas que el promedio anual de rentabilidad fue del 10,5%. Estimando la relación entre los rendimientos y las diversas variables explicativas, llegamos a la conclusión de que el rendimiento inicial está afectado positivamente por el exceso de demanda y el capital total, y correlacionado negativamente con las comisiones de suscripción, el precio de las ofertas y el importe total recaudado. Se demostró que la rentabilidad anual estaba correlacionada positivamente con la suscripción deficiente y negativamente con la rentabilidad inicial y la rentabilidad sobre el capita

The landscape of chromosomal aberrations in breast cancer mouse models reveals driver-specific routes to tumorigenesis

Aneuploidy and copy-number alterations (CNAs) are a hallmark of human cancer. Although genetically engineered mouse models (GEMMs) are commonly used to model human cancer, their chromosomal landscapes remain underexplored. Here we use gene expression profiles to infer CNAs in 3,108 samples from 45 mouse models, providing the first comprehensive catalogue of chromosomal aberrations in cancer GEMMs. Mining this resource, we find that most chromosomal aberrations accumulate late during breast tumorigenesis, and observe marked differences in CNA prevalence between mouse mammary tumours initiated with distinct drivers. Some aberrations are recurrent and unique to specific GEMMs, suggesting distinct driver-dependent routes to tumorigenesis. Synteny-based comparison of mouse and human tumours narrows critical regions in CNAs, thereby identifying candidate driver genes. We experimentally validate that loss of Stratifin (SFN) promotes HER2-induced tumorigenesis in human cells. These results demonstrate the power of GEMM CNA analysis to inform the pathogenesis of human cancer

Human Muscle Progenitor Cells Overexpressing Neurotrophic Factors Improve Neuronal Regeneration in a Sciatic Nerve Injury Mouse Model

The peripheral nervous system has an intrinsic ability to regenerate after injury. However, this process is slow, incomplete, and often accompanied by disturbing motor and sensory consequences. Sciatic nerve injury (SNI), which is the most common model for studying peripheral nerve injury, is characterized by damage to both motor and sensory fibers. The main goal of this study is to examine the feasibility of administration of human muscle progenitor cells (hMPCs) overexpressing neurotrophic factor (NTF) genes, known to protect peripheral neurons and enhance axon regeneration and functional recovery, to ameliorate motoric and sensory deficits in SNI mouse model. To this end, hMPCs were isolated from a human muscle biopsy, and manipulated to ectopically express brain-derived neurotrophic factor (BDNF), glial-cell-line-derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF-1). These hMPC-NTF were transplanted into the gastrocnemius muscle of mice after SNI, and motor and sensory functions of the mice were assessed using the CatWalk XT system and the hot plate test. ELISA analysis showed that genetically manipulated hMPC-NTF express significant amounts of BDNF, GDNF, VEGF, or IGF-1. Transplantation of 3 × 106 hMPC-NTF was shown to improve motor function and gait pattern in mice following SNI surgery, as indicated by the CatWalk XT system 7 days post-surgery. Moreover, using the hot-plate test, performed 6 days after surgery, the treated mice showed less sensory deficits, indicating a palliative effect of the treatment. ELISA analysis following transplantation demonstrated increased NTF expression levels in the gastrocnemius muscle of the treated mice, reinforcing the hypothesis that the observed positive effect was due to the transplantation of the genetically manipulated hMPC-NTF. These results show that genetically modified hMPC can alleviate both motoric and sensory deficits of SNI. The use of hMPC-NTF demonstrates the feasibility of a treatment paradigm, which may lead to rapid, high-quality healing of damaged peripheral nerves due to administration of hMPC. Our approach suggests a possible clinical application for the treatment of peripheral nerve injury

Gene copy-number changes and chromosomal instability induced by aneuploidy confer resistance to chemotherapy

Mitotic errors lead to aneuploidy, a condition of karyotype imbalance, frequently found in cancer cells. Alterations in chromosome copy number induce a wide variety of cellular stresses, including genome instability. Here, we show that cancer cells might exploit aneuploidy-induced genome instability and the resulting gene copy-number changes to survive under conditions of selective pressure, such as chemotherapy. Resistance to chemotherapeutic drugs was dictated by the acquisition of recurrent karyotypes, indicating that gene dosage might play a role in driving chemoresistance. Thus, our study establishes a causal link between aneuploidy-driven changes in gene copy number and chemoresistance and might explain why some chemotherapies fail to succeed

Comparison of Short- and Long-Term Effectiveness between Anti-TNF and Ustekinumab after Vedolizumab Failure as First-Line Therapy in Crohn's Disease: A Multi-Center Retrospective Cohort Study

BACKGROUND The effectiveness of anti-TNF or ustekinumab (UST) as a second-line biologic after vedolizumab (VDZ) failure has not yet been described. AIMS AND METHODS In this retrospective multicenter cohort study, We aim to investigate the effectiveness of anti-TNF and UST as second-line therapy in patients with Crohn's disease (CD) who failed VDZ as a first-line treatment. The primary outcome was clinical response at week 16-22. Secondary outcomes included the rates of clinical remission, steroid-free clinical remission, CRP normalization, and adverse events. RESULTS Fifty-nine patients who failed on VDZ as a first-line treatment for CD were included; 52.8% patients received anti-TNF and 47.2% UST as a second-line therapy. In initial period (Week 16-22), the clinical response and remission rate was similar between both groups: 61.2% vs. 68%, p = 0.8 and 48.3% vs. 56%, p = 0.8 on anti-TNF and UST therapy, respectively. Furthermore, in the maintenance period the rate was similar: 75% vs. 82.3%, p = 0.8 and 62.5% vs. 70.5%, p = 0.8, respectively. Of the patients, 12 out of the 59 stopped the therapy, without a significant difference between the two groups (p = 0.6). CONCLUSION Second-line biological therapy after VDZ failure therapy was effective in >60% of the patients with CD. No differences in effectiveness were detected between the use of anti-TNF and UST as a second line

Four Linked Genes Participate in Controlling Sporulation Efficiency in Budding Yeast

Quantitative traits are conditioned by several genetic determinants. Since such genes influence many important complex traits in various organisms, the identification of quantitative trait loci (QTLs) is of major interest, but still encounters serious difficulties. We detected four linked genes within one QTL, which participate in controlling sporulation efficiency in Saccharomyces cerevisiae. Following the identification of single nucleotide polymorphisms by comparing the sequences of 145 genes between the parental strains SK1 and S288c, we analyzed the segregating progeny of the cross between them. Through reciprocal hemizygosity analysis, four genes, RAS2, PMS1, SWS2, and FKH2, located in a region of 60 kilobases on Chromosome 14, were found to be associated with sporulation efficiency. Three of the four “high” sporulation alleles are derived from the “low” sporulating strain. Two of these sporulation-related genes were verified through allele replacements. For RAS2, the causative variation was suggested to be a single nucleotide difference in the upstream region of the gene. This quantitative trait nucleotide accounts for sporulation variability among a set of ten closely related winery yeast strains. Our results provide a detailed view of genetic complexity in one “QTL region” that controls a quantitative trait and reports a single nucleotide polymorphism-trait association in wild strains. Moreover, these findings have implications on QTL identification in higher eukaryotes

Assessing the Safety of Stem Cell Therapeutics

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

Assessing the Safety of Human Pluripotent Stem Cells and Their Derivatives for Clinical Applications

Pluripotent stem cells may acquire genetic and epigenetic variants during culture following their derivation. At a conference organized by the International Stem Cell Initiative, and held at The Jackson Laboratory, Bar Harbor, Maine, October 2016, participants discussed how the appearance of such variants can be monitored and minimized and, crucially, how their significance for the safety of therapeutic applications of these cells can be assessed. A strong recommendation from the meeting was that an international advisory group should be set up to review the genetic and epigenetic changes observed in human pluripotent stem cell lines and establish a framework for evaluating the risks that they may pose for clinical use.Funding for The International Stem Cell Initiative and for this meeting were provided by the International Stem Cell Forum (http://www.stem-cell-forum.net). Additional support for the meeting was provided by the Pluripotent Stem Cell Platform, a Hub funded by the UK Regenerative Medicine Platform, grant ref. MR/L012537/1, and also by Ajinomoto Inc., Stem Cell Technologies Inc. and Thermo Fisher Scientific. B.R. is founder, chief scientific officer, shareholder, and has interests in Cell Cure Neurosciences Ltd