技术资料

The placenta and umbilical cord are pre-eminent candidate sources of mesenchymal stem cells (MSCs). However,placenta-derived MSCs (P-MSCs) showed greater proliferation capacity than umbilical cord-derived MSCs (UC-MSCs) in our study. We investigated the drivers of this proliferation difference and elucidated the mechanisms of proliferation regulation. Proteomic profiling and Gene Ontology (GO) functional enrichment were conducted to identify candidate proteins that may influence proliferation. Using lentiviral or small interfering RNA infection,we established overexpression and knockdown models and observed changes in cell proliferation to examine whether a relationship exists between the candidate proteins and proliferation capacity. Real-time quantitative polymerase chain reaction,western blot analysis,and immunofluorescence assays were conducted to elucidate the mechanisms underlying proliferation. Six candidate proteins were selected based on the results of proteomic profiling and GO functional enrichment. Through further validation,yes-associated protein 1 (YAP1) and $\beta$-catenin were confirmed to affect MSCs proliferation rates. YAP1 and $\beta$-catenin showed increased nuclear colocalization during cell expansion. YAP1 overexpression significantly enhanced proliferation capacity and upregulated the expression of both $\beta$-catenin and the transcriptional targets of Wnt signaling,CCND1,and c-MYC,whereas silencing $\beta$-catenin attenuated this influence. We found that YAP1 directly interacts with $\beta$-catenin in the nucleus to form a transcriptional YAP/$\beta$-catenin/TCF4 complex. Our study revealed that YAP1 and $\beta$-catenin caused the different proliferation capacities of P-MSCs and UC-MSCs. Mechanism analysis showed that YAP1 stabilized the nuclear $\beta$-catenin protein,and also triggered the Wnt/$\beta$-catenin pathway,promoting proliferation. View Publication

The tumor microenvironment (TME) comprises complex interactions of multiple cell types that determines cell behavior and metabolism such as nutrient competition and immune suppression. We discuss the various types of heterogeneity that exist in solid tumors,and the complications this invokes for studies of TME. As human subjects and in vivo model systems are complex and difficult to manipulate,simpler 3D model systems that are compatible with flexible experimental control are necessary for studying metabolic regulation in TME. Stable Isotope Resolved Metabolomics (SIRM) is a valuable tool for tracing metabolic networks in complex systems,but at present does not directly address heterogeneous metabolism at the individual cell level. We compare the advantages and disadvantages of different model systems for SIRM experiments,with a focus on lung cancer cells,their interactions with macrophages and T cells,and their response to modulators in the immune microenvironment. We describe the experimental set up,illustrate results from 3D cultures and co-cultures of lung cancer cells with human macrophages,and outline strategies to address the heterogeneous TME. View Publication

Tissue resident intestinal macrophages are known to exhibit an anti-inflammatory phenotype and produce little pro-inflammatory cytokines upon TLR ligation,allowing symbiotic co-existence with the intestinal microbiota. However,upon acute events such as epithelial damage and concomitant influx of microbes,these macrophages must be able to quickly mount a pro-inflammatory response while more inflammatory macrophages are recruited from the blood stream simultaneously. Here,we show that dietary intake of vitamin A is required for the maintenance of the anti-inflammatory state of tissue resident intestinal macrophages. Interestingly,these anti-inflammatory macrophages were characterized by high levels of Dectin-1 expression. We show that Dectin-1 expression is enhanced by the vitamin A metabolite retinoic acid and our data suggests that Dectin-1 triggering might provide a switch to induce a rapid production of pro-inflammatory cytokines. In addition,Dectin-1 stimulation resulted in an altered metabolic profile which is linked to a pro-inflammatory response. Together,our data suggests that presence of vitamin A in the small intestine enhances an anti-inflammatory phenotype as well as Dectin-1 expression by macrophages and that this anti-inflammatory phenotype can rapidly convert toward a pro-inflammatory state upon Dectin-1 signaling. View Publication

Crosstalk between mesenchymal stromal cells (MSCs) and hematopoietic stem cells (HSCs) is essential for hematopoietic homeostasis and lineage output. Here,we investigate how transcriptional changes in bone marrow (BM) MSCs result in long-lasting effects on HSCs. Single-cell analysis of Cxcl12-abundant reticular (CAR) cells and PDGFR$\alpha$+Sca1+ (P$\alpha$S) cells revealed an extensive cellular heterogeneity but uniform expression of the transcription factor gene Ebf1. Conditional deletion of Ebf1 in these MSCs altered their cellular composition,chromatin structure and gene expression profiles,including the reduced expression of adhesion-related genes. Functionally,the stromal-specific Ebf1 inactivation results in impaired adhesion of HSCs,leading to reduced quiescence and diminished myeloid output. Most notably,HSCs residing in the Ebf1-deficient niche underwent changes in their cellular composition and chromatin structure that persist in serial transplantations. Thus,genetic alterations in the BM niche lead to long-term functional changes of HSCs. View Publication

Mast cells (MCs) arise from hematopoietic stem cells (HSCs) that mature within vascularized tissues. Fibroblasts and endothelial cells (ECs) play a role in the maturation of HSCs in the tissues. Due to difficulties in isolating MCs from tissues,large numbers of committed MC precursors can be generated in 2D culture systems with the use of differentiation factors. Since MCs are tissue-resident cells,the development of a 3D tissue-engineered model with ancillary cells that more closely mimics the 3D in vivo microenvironment has greater relevance for MC studies. The goals of this study were to show that MCs can be derived from HSCs within a 3D matrix and to determine a media to support MCs,fibroblasts,and ECs. The results show that HSCs within a collagen matrix cultured in StemSpan media with serum added at the last week yielded a greater number of c-kit+ cells and a greater amount of histamine granules compared to other media tested. Media supplemented with serum were necessary for EC survival,while fibroblasts survived irrespective of serum with higher cell yields in StemSpan. This work demonstrates the development of functional MCs within a 3D collagen matrix using a stem cell media that supports fibroblast and ECs. View Publication

Gelatin coatings are effective in increasing the retention of MSCs injected into the heart and minimizing the damage from acute myocardial infarction (AMI),but early studies suffered from low fractions of the MSCs coated with gelatin. Biotinylation of the MSC surface is a critical first step in the gelatin coating process,and in this study,we evaluated the use of biotinylated cholesterol lipid insertion" anchors as a substitute for the covalent NHS-biotin anchors to the cell surface. Streptavidin-eosin molecules where eosin is our photoinitiator can then be bound to the cell surface through biotin-streptavidin affinity. The use of cholesterol anchors increased streptavidin density on the surface of MSCs further driving polymerization and allowing for an increased fraction of MSCs coated with gelatin (83{\%}) when compared to NHS-biotin (52{\%}). Additionally the cholesterol anchors increased the uniformity of the coating on the MSC surface and supported greater numbers of coated MSCs even when the streptavidin density was slightly lower than that of an NHS-biotin anchoring strategy. Critically this improvement in gelatin coating efficiency did not impact cytokine secretion and other critical MSC functions. Proper selection of the cholesterol anchor and the biotinylation conditions supports cellular function and densities of streptavidin on the MSC surface of up to {\~{}}105 streptavidin molecules/$\mu$m2 . In all these cholesterol anchors offer an effective path towards the formation of conformal coatings on the majority of MSCs to improve the retention of MSCs in the heart following AMI." View Publication

The discovery and study of human neural stem cells has advanced our understanding of human neurogenesis,and the development of novel therapeutics based on neural cell replacement. Here,we describe methods to culture and cryopreserve human neural stem cells (hNSCs) for expansion and banking. Importantly,the protocols ensure that the multipotency of hNSCs is preserved to enable differentiation to neurons and supporting neuroglia. View Publication

Thrombosis is a major cause of mortality in patients with myeloproliferative neoplasms (MPNs),though there is currently little to offer patients with MPN beyond aspirin and cytoreductive therapies such as hydroxyurea for primary prevention. Thrombogenesis in MPN involves multiple cellular mechanisms,including platelet activation and neutrophil-extracellular trap formation; therefore,an antithrombotic agent that targets one or more of these processes would be of therapeutic benefit in MPN. Here,we treated the JAK2V617F knockin mouse model of polycythemia vera with N-acetylcysteine (NAC),a sulfhydryl-containing compound with broad effects on glutathione replenishment,free radical scavenging,and reducing disulfide bonds,to investigate its antithrombotic effects in the context of MPN. Strikingly,NAC treatment extended the lifespan of JAK2V617F mice without impacting blood counts or splenomegaly. Using an acute pulmonary thrombosis model in vivo,we found that NAC reduced thrombus formation to a similar extent as the irreversible platelet inhibitor aspirin. In vitro analysis of platelet activation revealed that NAC reduced thrombin-induced platelet-leukocyte aggregate formation in JAK2V617F mice. Furthermore,NAC reduced neutrophil extracellular trap formation in primary human neutrophils from patients with MPN as well as healthy controls. These results provide evidence that N-acetylcysteine inhibits thrombosis in JAK2V617F mice and provide a pre-clinical rationale for investigating NAC as a therapeutic to reduce thrombotic risk in MPN. View Publication

Cancer stem cells are critical for cancer initiation,development,and treatment resistance. Our understanding of these processes,and how they relate to glioblastoma heterogeneity,is limited. To overcome these limitations,we performed single-cell RNA sequencing on 53586 adult glioblastoma cells and 22637 normal human fetal brain cells,and compared the lineage hierarchy of the developing human brain to the transcriptome of cancer cells. We find a conserved neural tri-lineage cancer hierarchy centered around glial progenitor-like cells. We also find that this progenitor population contains the majority of the cancer's cycling cells,and,using RNA velocity,is often the originator of the other cell types. Finally,we show that this hierarchal map can be used to identify therapeutic targets specific to progenitor cancer stem cells. Our analyses show that normal brain development reconciles glioblastoma development,suggests a possible origin for glioblastoma hierarchy,and helps to identify cancer stem cell-specific targets. View Publication

Cell-to-cell communication by exosomes controls normal and pathogenic processes1,2. Viruses can spread in exosomes and thereby avoid immune recognition3. While biogenesis,binding and uptake of exosomes are well characterized4,5,delivery of exosome cargo into the cytoplasm is poorly understood3. We report that the phosphatidylserine receptor HAVCR1 (refs. 6,7) and the cholesterol transporter NPC1 (ref. 8) participate in cargo delivery from exosomes of hepatitis A virus (HAV)-infected cells (exo-HAV) by clathrin-mediated endocytosis. Using CRISPR-Cas9 knockout technology,we show that these two lipid receptors,which interact in the late endosome9,are necessary for the membrane fusion and delivery of RNA from exo-HAV into the cytoplasm. The HAVCR1-NPC1 pathway,which Ebola virus exploits to infect cells9,mediates HAV infection by exo-HAV,which indicates that viral infection via this exosome mimicry mechanism does not require an envelope glycoprotein. The capsid-free viral RNA in the exosome lumen,but not the endosomal uncoating of HAV particles contained in the exosomes,is mainly responsible for exo-HAV infectivity as assessed by methylene blue inactivation of non-encapsidated RNA. In contrast to exo-HAV,infectivity of HAV particles is pH-independent and requires HAVCR1 or another as yet unidentified receptor(s) but not NPC1. Our findings show that envelope-glycoprotein-independent fusion mechanisms are shared by exosomes and viruses,and call for a reassessment of the role of envelope glycoproteins in infection. View Publication

Preclinical in vitro models provide an essential tool to study cancer cell biology as well as aid in translational research,including drug target identification and drug discovery efforts. For any model to be clinically relevant,it needs to recapitulate the biology and cell heterogeneity of the primary tumor. We recently developed and described a conditional reprogramming (CR) cell technology that addresses many of these needs and avoids the deficiencies of most current cancer cell lines,which are usually clonal in origin. Here,we used the CR cell method to generate a collection of patient-derived cell cultures from non-small cell lung cancers (NSCLC). Whole exome sequencing and copy number variations are used for the first time to address the capability of CR cells to keep their tumor-derived heterogeneity. Our results indicated that these primary cultures largely maintained the molecular characteristics of the original tumors. Using a mutant-allele tumor heterogeneity (MATH) score,we showed that CR cells are able to keep and maintain most of the intra-tumoral heterogeneity,suggesting oligoclonality of these cultures. CR cultures therefore represent a pre-clinical lung cancer model for future basic and translational studies. View Publication

Human-based body-on-a-chip" technology provides powerful platforms in developing models for drug evaluation and disease evaluations in phenotypic models. Induced pluripotent stem cells (iPSCs) are ideal cell sources for generating different cell types for these in vitro functional systems and recapitulation of the neuromuscular reflex arc would allow for the study of patient specific neuromuscular diseases. Regarding relevant afferent (intrafusal fibers sensory neurons) and efferent (extrafusal fibers motoneurons) cells in vitro differentiation of intrafusal fiber from human iPSCs has not been established. This work demonstrates a protocol for inducing an enrichment of intrafusal bag fibers from iPSCs using morphological analysis and immunocytochemistry. Phosphorylation of the ErbB2 receptors and S46 staining indicated a 3-fold increase of total intrafusal fibers further confirming the efficiency of the protocol. Integration of induced intrafusal fibers would enable more accurate reflex arc models and application of this protocol on patient iPSCs would allow for patient-specific disease modeling." View Publication