技术资料

Human induced pluripotent stem cells (hiPSCs) secrete essential autocrine factors that are removed along with toxic metabolites when the growth medium is exchanged daily. In this study,after determining the minimum inhibitory level of lactic acid for hiPSCs,a medium refining system was constructed by which toxic metabolites were removed from used culture medium and autocrine factors as well as other growth factors were recycled. Specifically,about 87 % of the basic fibroblast growth factor and 80 % of transforming growth factor beta 1 were retained in the refined medium after dialysis. The refined medium efficiently potentiated the proliferation of hiPS cells in adherent culture. When the refining system was used to refresh medium in suspension culture,a final cell density of (1.1 ± 0.1) × 10(6) cells mL(-1) was obtained,with 99.5 ± 0.2 % OCT 3/4 and 78.3 ± 1.1 % TRA-1-60 expression,on day 4 of culture. These levels of expression were similar to those observed in the conventional suspension culture. With this method,culture medium refinement by dialysis was established to remove toxic metabolites,recycle autocrine factors as well as other growth factors,and reduce the use of macromolecules for the expansion of hiPSCs in suspension culture. View Publication

Leukocyte microvilli are flexible projections enriched with adhesion molecules. The role of these cellular projections in the ability of T cells to probe antigen-presenting cells has been elusive. In this study,we probe the spatial relation of microvilli and T-cell receptors (TCRs),the major molecules responsible for antigen recognition on the T-cell membrane. To this end,an effective and robust methodology for mapping membrane protein distribution in relation to the 3D surface structure of cells is introduced,based on two complementary superresolution microscopies. Strikingly,TCRs are found to be highly localized on microvilli,in both peripheral blood human T cells and differentiated effector T cells,and are barely found on the cell body. This is a decisive demonstration that different types of T cells universally localize their TCRs to microvilli,immediately pointing to these surface projections as effective sensors for antigenic moieties. This finding also suggests how previously reported membrane clusters might form,with microvilli serving as anchors for specific T-cell surface molecules. View Publication

BACKGROUND Recently,accumulating evidence has shown that exosomes,the naturally secreted nanocarriers of cells,can exert therapeutic effects in various disease models in the absence of parent cells. However,application of exosomes in bone defect repair and regeneration has been rarely reported,and little is known regarding their underlying mechanisms. METHODS Exosomes derived from human-induced pluripotent stem cell-derived mesenchymal stem cells (hiPS-MSC-Exos) were combined with tricalcium phosphate (β-TCP) to repair critical-sized calvarial bone defects,and the efficacy was assessed by histological examination. We evaluated the in vitro effects of hiPSC-MSC-Exos on the proliferation,migration,and osteogenic differentiation of human bone marrow-derived mesenchymal stem cells (hBMSCs) by cell-counting,scratch assays,and qRT-PCR,respectively. Gene expression profiling and bioinformatics analyses were also used to identify the underlying mechanisms in the repair. RESULTS We found that the exosome/β-TCP combination scaffolds could enhance osteogenesis as compared to pure β-TCP scaffolds. In vitro assays showed that the exosomes could release from β-TCP and could be internalized by hBMSCs. In addition,the internalization of exosomes into hBMSCs could profoundly enhance the proliferation,migration,and osteogenic differentiation of hBMSCs. Furthermore,gene expression profiling and bioinformatics analyses demonstrated that exosome/β-TCP combination scaffolds significantly altered the expression of a network of genes involved in the PI3K/Akt signaling pathway. Functional studies further confirmed that the PI3K/Akt signaling pathway was the critical mediator during the exosome-induced osteogenic responses of hBMSCs. CONCLUSIONS We propose that the exosomes can enhance the osteoinductivity of β-TCP through activating the PI3K/Akt signaling pathway of hBMSCs,which means that the exosome/β-TCP combination scaffolds possess better osteogenesis activity than pure β-TCP scaffolds. These results indicate that naturally secreted nanocarriers-exosomes can be used as a bioactive material to improve the bioactivity of the biomaterials,and that hiPS-MSC-Exos combined with β-TCP scaffolds can be potentially used for repairing bone defects. View Publication

Regulation of gene expression in immune cells is known to be under genetic control,and likely contributes to susceptibility to autoimmune diseases such as multiple sclerosis (MS). How this occurs in concert across multiple immune cell types is poorly understood. Using a mouse model that harnesses the genetic diversity of wild-derived mice,more accurately reflecting genetically diverse human populations,we provide an extensive characterization of the genetic regulation of gene expression in five different naive immune cell types relevant to MS. The immune cell transcriptome is shown to be under profound genetic control,exhibiting diverse patterns: global,cell-specific and sex-specific. Bioinformatic analysis of the genetically controlled transcript networks reveals reduced cell type specificity and inflammatory activity in wild-derived PWD/PhJ mice,compared with the conventional laboratory strain C57BL/6J. Additionally,candidate MS-GWAS (genome-wide association study candidate genes for MS susceptibility) genes were significantly enriched among transcripts overrepresented in C57BL/6J cells compared with PWD. These expression level differences correlate with robust differences in susceptibility to experimental autoimmune encephalomyelitis,the principal model of MS,and skewing of the encephalitogenic T-cell responses. Taken together,our results provide functional insights into the genetic regulation of the immune transcriptome,and shed light on how this in turn contributes to susceptibility to autoimmune disease.Genes and Immunity advance online publication,22 September 2016; doi:10.1038/gene.2016.37. View Publication

Autosomal dominant vitreoretinochoroidopathy (ADVIRC) is a rare,early-onset retinal dystrophy characterised by distinct bands of circumferential pigmentary degeneration in the peripheral retina and developmental eye defects. ADVIRC is caused by mutations in the Bestrophin1 (BEST1) gene,which encodes a transmembrane protein thought to function as an ion channel in the basolateral membrane of retinal pigment epithelial (RPE) cells. Previous studies suggest that the distinct ADVIRC phenotype results from alternative splicing of BEST1 pre-mRNA. Here,we have used induced pluripotent stem cell (iPSC) technology to investigate the effects of an ADVIRC associated BEST1 mutation (c.704T textgreater C,p.V235A) in patient-derived iPSC-RPE. We found no evidence of alternate splicing of the BEST1 transcript in ADVIRC iPSC-RPE,however in patient-derived iPSC-RPE,BEST1 was expressed at the basolateral membrane and the apical membrane. During human eye development we show that BEST1 is expressed more abundantly in peripheral RPE compared to central RPE and is also expressed in cells of the developing retina. These results suggest that higher levels of mislocalised BEST1 expression in the periphery,from an early developmental stage,could provide a mechanism that leads to the distinct clinical phenotype observed in ADVIRC patients. View Publication

T cell activation in response to Ag is largely regulated by protein posttranslational modifications. Although phosphorylation has been extensively characterized in T cells,much less is known about the glycosylation of serine/threonine residues by O-linked N-acetylglucosamine (O-GlcNAc). Given that O-GlcNAc appears to regulate cell signaling pathways and protein activity similarly to phosphorylation,we performed a comprehensive analysis of O-GlcNAc during T cell activation to address the functional importance of this modification and to identify the modified proteins. Activation of T cells through the TCR resulted in a global elevation of O-GlcNAc levels and in the absence of O-GlcNAc,IL-2 production and proliferation were compromised. T cell activation also led to changes in the relative expression of O-GlcNAc transferase (OGT) isoforms and accumulation of OGT at the immunological synapse of murine T cells. Using a glycoproteomics approach,we identified textgreater200 O-GlcNAc proteins in human T cells. Many of the identified proteins had a functional relationship to RNA metabolism,and consistent with a connection between O-GlcNAc and RNA,inhibition of OGT impaired nascent RNA synthesis upon T cell activation. Overall,our studies provide a global analysis of O-GlcNAc dynamics during T cell activation and the first characterization,to our knowledge,of the O-GlcNAc glycoproteome in human T cells. View Publication

We report a method of high-speed phase contrast and bright field microscopy which permits large cell culture vessels to be scanned at much higher speed (up to 30 times faster) than when conventional methods are used without compromising image quality. The object under investigation moves continuously and is captured using a flash illumination which creates an exposure time short enough to prevent motion blur. During the scan the object always stays in focus due to a novel hardware-autofocus system. View Publication

While a third of the world carries the burden of tuberculosis,disease control has been hindered by a lack of tools,including a rapid,point-of-care diagnostic and a protective vaccine. In many infectious diseases,antibodies (Abs) are powerful biomarkers and important immune mediators. However,in Mycobacterium tuberculosis (Mtb) infection,a discriminatory or protective role for humoral immunity remains unclear. Using an unbiased antibody profiling approach,we show that individuals with latent tuberculosis infection (Ltb) and active tuberculosis disease (Atb) have distinct Mtb-specific humoral responses,such that Ltb infection is associated with unique Ab Fc functional profiles,selective binding to FcγRIII,and distinct Ab glycosylation patterns. Moreover,compared to Abs from Atb,Abs from Ltb drove enhanced phagolysosomal maturation,inflammasome activation,and,most importantly,macrophage killing of intracellular Mtb. Combined,these data point to a potential role for Fc-mediated Ab effector functions,tuned via differential glycosylation,in Mtb control. View Publication

Human neocortex expansion likely contributed to the remarkable cognitive abilities of humans. This expansion is thought to primarily reflect differences in proliferation versus differentiation of neural progenitors during cortical development. Here,we have searched for such differences by analysing cerebral organoids from human and chimpanzees using immunohistochemistry,live imaging,and single-cell transcriptomics. We find that the cytoarchitecture,cell type composition,and neurogenic gene expression programs of humans and chimpanzees are remarkably similar. Notably,however,live imaging of apical progenitor mitosis uncovered a lengthening of prometaphase-metaphase in humans compared to chimpanzees that is specific to proliferating progenitors and not observed in non-neural cells. Consistent with this,the small set of genes more highly expressed in human apical progenitors points to increased proliferative capacity,and the proportion of neurogenic basal progenitors is lower in humans. These subtle differences in cortical progenitors between humans and chimpanzees may have consequences for human neocortex evolution. View Publication

Human pluripotent stem cell (hPSC) derived tissues often remain developmentally immature in vitro,and become more adult-like in their structure,cellular diversity and function following transplantation into immunocompromised mice. Previously we have demonstrated that hPSC-derived human lung organoids (HLOs) resembled human fetal lung tissue in vitro (Dye et al.,2015). Here we show that HLOs required a bioartificial microporous poly(lactide-co-glycolide) (PLG) scaffold niche for successful engraftment,long-term survival,and maturation of lung epithelium in vivo. Analysis of scaffold-grown transplanted tissue showed airway-like tissue with enhanced epithelial structure and organization compared to HLOs grown in vitro. By further comparing in vitro and in vivo grown HLOs with fetal and adult human lung tissue,we found that in vivo transplanted HLOs had improved cellular differentiation of secretory lineages that is reflective of differences between fetal and adult tissue,resulting in airway-like structures that were remarkably similar to the native adult human lung. View Publication