参考文献

Our understanding of the signalling pathways regulating early human development is limited,despite their fundamental biological importance. Here,we mine transcriptomics datasets to investigate signalling in the human embryo and identify expression for the insulin and insulin growth factor 1 (IGF1) receptors,along with IGF1 ligand. Consequently,we generate a minimal chemically-defined culture medium in which IGF1 together with Activin maintain self-renewal in the absence of fibroblast growth factor (FGF) signalling. Under these conditions,we derive several pluripotent stem cell lines that express pluripotency-associated genes,retain high viability and a normal karyotype,and can be genetically modified or differentiated into multiple cell lineages. We also identify active phosphoinositide 3-kinase (PI3K)/AKT/mTOR signalling in early human embryos,and in both primed and na{\{i}}ve pluripotent culture conditions. This demonstrates that signalling insights from human blastocysts can be used to define culture conditions that more closely recapitulate the embryonic niche." View Publication

Developmental and/or epileptic encephalopathies (DEEs) are a group of devastating genetic disorders,resulting in early-onset,therapy-resistant seizures and developmental delay. Here we report on 22 individuals from 15 families presenting with a severe form of intractable epilepsy,severe developmental delay,progressive microcephaly,visual disturbance and similar minor dysmorphisms. Whole exome sequencing identified a recurrent,homozygous variant (chr2:64083454A {\textgreater} G) in the essential UDP-glucose pyrophosphorylase (UGP2) gene in all probands. This rare variant results in a tolerable Met12Val missense change of the longer UGP2 protein isoform but causes a disruption of the start codon of the shorter isoform,which is predominant in brain. We show that the absence of the shorter isoform leads to a reduction of functional UGP2 enzyme in neural stem cells,leading to altered glycogen metabolism,upregulated unfolded protein response and premature neuronal differentiation,as modeled during pluripotent stem cell differentiation in vitro. In contrast,the complete lack of all UGP2 isoforms leads to differentiation defects in multiple lineages in human cells. Reduced expression of Ugp2a/Ugp2b in vivo in zebrafish mimics visual disturbance and mutant animals show a behavioral phenotype. Our study identifies a recurrent start codon mutation in UGP2 as a cause of a novel autosomal recessive DEE syndrome. Importantly,it also shows that isoform-specific start-loss mutations causing expression loss of a tissue-relevant isoform of an essential protein can cause a genetic disease,even when an organism-wide protein absence is incompatible with life. We provide additional examples where a similar disease mechanism applies. View Publication

Understanding the root causes of autoimmune diseases is hampered by the inability to access relevant human tissues and identify the time of disease onset. To examine the interaction of immune cells and their cellular targets in type 1 diabetes,we differentiated human induced pluripotent stem cells into pancreatic endocrine cells,including $\beta$ cells. Here,we describe an in vitro platform that models features of human type 1 diabetes using stress-induced patient-derived endocrine cells and autologous immune cells. We demonstrate a cell-type-specific response by autologous immune cells against induced pluripotent stem cell-derived $\beta$ cells,along with a reduced effect on $\alpha$ cells. This approach represents a path to developing disease models that use patient-derived cells to predict the outcome of an autoimmune response. View Publication

Progressive resistance exercise training (PRT) is the most effective known intervention for combating aging skeletal muscle atrophy. However,the hypertrophic response to PRT is variable,and this may be due to muscle inflammation susceptibility. Metformin reduces inflammation,so we hypothesized that metformin would augment the muscle response to PRT in healthy women and men aged 65 and older. In a randomized,double-blind trial,participants received 1,700 mg/day metformin (N = 46) or placebo (N = 48) throughout the study,and all subjects performed 14 weeks of supervised PRT. Although responses to PRT varied,placebo gained more lean body mass (p = .003) and thigh muscle mass (p {\textless} .001) than metformin. CT scan showed that increases in thigh muscle area (p = .005) and density (p = .020) were greater in placebo versus metformin. There was a trend for blunted strength gains in metformin that did not reach statistical significance. Analyses of vastus lateralis muscle biopsies showed that metformin did not affect fiber hypertrophy,or increases in satellite cell or macrophage abundance with PRT. However,placebo had decreased type I fiber percentage while metformin did not (p = .007). Metformin led to an increase in AMPK signaling,and a trend for blunted increases in mTORC1 signaling in response to PRT. These results underscore the benefits of PRT in older adults,but metformin negatively impacts the hypertrophic response to resistance training in healthy older individuals. ClinicalTrials.gov Identifier: NCT02308228. View Publication

AIMS Current treatment for congenital long QT syndrome Type 2 (cLQTS2),an electrical disorder that increases the risk of life-threatening cardiac arrhythmias,is aimed at reducing the incidence of arrhythmia triggers (beta-blockers) or terminating the arrhythmia after onset (implantable cardioverter-defibrillator). An alternative strategy is to target the underlying disease mechanism,which is reduced rapid delayed rectifier current (IKr) passed by Kv11.1 channels. Small molecule activators of Kv11.1 have been identified but the extent to which these can restore normal cardiac signalling in cLQTS2 backgrounds remains unclear. Here,we examined the ability of ICA-105574,an activator of Kv11.1 that impairs transition to the inactivated state,to restore function to heterozygous Kv11.1 channels containing either inactivation enhanced (T618S,N633S) or expression deficient (A422T) mutations. METHODS AND RESULTS ICA-105574 effectively restored Kv11.1 current from heterozygous inactivation enhanced or expression defective mutant channels in heterologous expression systems. In a human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of cLQTS2 containing the expression defective Kv11.1 mutant A422T,cardiac repolarization,estimated from the duration of calcium transients in isolated cells and the rate corrected field potential duration (FPDc) in culture monolayers of cells,was significantly prolonged. The Kv11.1 activator ICA-105574 was able to reverse the prolonged repolarization in a concentration-dependent manner. However,at higher doses,ICA-105574 produced a shortening of the FPDc compared to controls. In vitro and in silico analysis suggests that this overcorrection occurs as a result of a temporal redistribution of the peak IKr to much earlier in the plateau phase of the action potential,which results in early repolarization. CONCLUSION Kv11.1 activators,which target the primary disease mechanism,provide a possible treatment option for cLQTS2,with the caveat that there may be a risk of overcorrection that could itself be pro-arrhythmic. View Publication

Induced pluripotent stem cells (iPSC) derived from healthy individuals are important controls for disease-modeling studies. Here we apply precision health to create a high-quality resource of control iPSCs. Footprint-free lines were reprogrammed from four volunteers of the Personal Genome Project Canada (PGPC). Multilineage-directed differentiation efficiently produced functional cortical neurons,cardiomyocytes and hepatocytes. Pilot users demonstrated versatility by generating kidney organoids,T lymphocytes,and sensory neurons. A frameshift knockout was introduced into MYBPC3 and these cardiomyocytes exhibited the expected hypertrophic phenotype. Whole-genome sequencing-based annotation of PGPC lines revealed on average 20 coding variants. Importantly,nearly all annotated PGPC and HipSci lines harbored at least one pre-existing or acquired variant with cardiac,neurological,or other disease associations. Overall,PGPC lines were efficiently differentiated by multiple users into cells from six tissues for disease modeling,and variant-preferred healthy control lines were identified for specific disease settings. View Publication

The routine application of human pluripotent stem cells (hPSCs) and their derivatives in biomedicine and drug discovery will require the constant supply of high-quality cells by defined processes. Culturing hPSCs as cell-only aggregates in (three-dimensional [3D]) suspension has the potential to overcome numerous limitations of conventional surface-adherent (two-dimensional [2D]) cultivation. Utilizing single-use instrumented stirred-tank bioreactors,we showed that perfusion resulted in a more homogeneous culture environment and enabled superior cell densities of 2.85 X 10(6) cells per milliliter and 47% higher cell yields compared with conventional repeated batch cultures. Flow cytometry,quantitative reverse-transcriptase polymerase chain reaction,and global gene expression analysis revealed a high similarity across 3D suspension and 2D precultures,underscoring that matrix-free hPSC culture efficiently supports maintenance of pluripotency. Interestingly,physiological data and gene expression assessment indicated distinct changes of the cells' energy metabolism,suggesting a culture-induced switch from glycolysis to oxidative phosphorylation in the absence of hPSC differentiation. Our data highlight the plasticity of hPSCs' energy metabolism and provide clear physiological and molecular targets for process monitoring and further development. This study paves the way toward more efficient GMP-compliant cell production and underscores the enormous process development potential of hPSCs in suspension culture. SIGNIFICANCE Human pluripotent stem cells (hPSCs) are a unique source for the,in principle,unlimited production of functional human cell types in vitro,which are of high value for therapeutic and industrial applications. This study applied single-use,clinically compliant bioreactor technology to develop advanced,matrix-free,and more efficient culture conditions for the mass production of hPSCs in scalable suspension culture. Using extensive analytical tools to compare established conditions with this novel culture strategy,unexpected physiological features of hPSCs were discovered. These data allow a more rational process development,providing significant progress in the field of translational stem cell research and medicine. View Publication

The neural crest is a source to produce multipotent neural crest stem cells that have a potential to differentiate into diverse cell types. The transcription factor SOX10 is expressed through early neural crest progenitors and stem cells in vertebrates. Here we report the generation of SOX10-Nano-lantern (NL) reporter human induced pluripotent stem cells (hiPS) by using CRISPR/Cas9 systems,that are beneficial to investigate the generation and maintenance of neural crest progenitor cells. SOX10-NL positive cells are produced transiently from hiPS cells by treatment with TGFβ inhibitor SB431542 and GSK3 inhibitor CHIR99021. We found that all SOX10-NL-positive cells expressed an early neural crest marker NGFR,however SOX10-NL-positive cells purified from differentiated hiPS cells progressively attenuate their NL-expression under proliferation. We therefore attempted to maintain SOX10-NL-positive cells with additional signaling on the plane and sphere culture conditions. These SOX10-NL cells provide us to investigate mass culture with neural crest cells for stem cell research. View Publication

Mitochondrial dysfunction has been demonstrated to result in premature aging due to its effects on stem cells. Nevertheless,a full understanding of the role of mitochondrial bioenergetics through differentiation is still lacking. Here we show the bioenergetics profile of human stem cells of embryonic origin differentiating along the hepatic lineage. Our study reveals especially the transition between hepatic specification and hepatic maturation as dependent on mitochondrial respiration and demonstrates that even though differentiating cells are primarily dependent on glycolysis until induction of hepatocyte maturation,oxidative phosphorylation is essential at all stages of differentiation. View Publication

The recent Zika virus (ZIKV) outbreak,which mainly affected Brazil and neighbouring states,demonstrated the paucity of information concerning the epidemiology of several flaviruses,but also highlighted the lack of available agents with which to treat such emerging diseases. Here,we show that heparin,a widely used anticoagulant,while exerting a modest inhibitory effect on Zika Virus replication,fully prevents virus-induced cell death of human neural progenitor cells (NPCs). View Publication