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Haematopoietic stem cells (HSCs) are derived early from embryonic precursors, such as haemogenic endothelial cells and pre-haematopoietic stem cells (pre-HSCs), the molecular identity of which still remains elusive. Here we use potent surface markers to capture the nascent pre-HSCs at high purity, as rigorously validated by single-cell-initiated serial transplantation. Then we apply single-cell RNA sequencing to analyse endothelial cells, CD45.sup.- and CD45.sup.+ pre-HSCs in the aorta-gonad-mesonephros region, and HSCs in fetal liver. Pre-HSCs show unique features in transcriptional machinery, arterial signature, metabolism state, signalling pathway, and transcription factor network. Functionally, activation of mechanistic targets of rapamycin (mTOR) is shown to be indispensable for the emergence of HSCs but not haematopoietic progenitors. Transcriptome data-based functional analysis reveals remarkable heterogeneity in cell-cycle status of pre-HSCs. Finally, the core molecular signature of pre-HSCs is identified. Collectively, our work paves the way for dissection of complex molecular mechanisms regulating stepwise generation of HSCs in vivo, informing future efforts to engineer HSCs for clinical applications. Successful identification of mouse embryonic pre-haematopoietic stem cells at single-cell resolution. Haematopoietic stem cell formation dissected Fuchou Tang and colleagues have isolated the earliest haematopoietic stem cell (HSC) precursors -- rare CD45-negative pre-HSCs -- from developing mouse embryos using a combination of surface marker expression and single-cell-based transplantation assays, assessing blood-forming capacity. Single-cell RNA-seq was used to analyse the transcriptomes for five types of cells related to HSC formation, revealing a role for mTOR activation in the emergence of HSCs but not haematopoietic progenitors., Author(s): Fan Zhou [sup.1] , Xianlong Li [sup.2] , Weili Wang [sup.3] , Ping Zhu [sup.2] [sup.4] , Jie Zhou [sup.1] , Wenyan He [sup.1] , Meng Ding [sup.1] , [...]

In the aorta of mid‐gestational mouse embryos, a specialized endothelial subpopulation termed hemogenic endothelial cells (HECs) develops into hematopoietic stem and progenitor cells (HSPCs), through a conserved process of endothelial‐to‐hematopoietic transition (EHT). EHT is tightly controlled by multiple intrinsic and extrinsic mechanisms. Nevertheless, the molecular regulators restraining this process remain poorly understood. Here, it is uncovered that, one of the previously identified HEC signature genes, Nupr1, negatively regulates the EHT process. Nupr1 deletion in endothelial cells results in increased HSPC generation in the aorta‐gonad‐mesonephros region. Furthermore, single‐cell transcriptomics combined with serial functional assays reveals that loss of Nupr1 promotes the EHT process by promoting the specification of hematopoiesis‐primed functional HECs and strengthening their subsequent hematopoietic differentiation potential toward HSPCs. This study further finds that the proinflammatory cytokine, tumor necrosis factor α (TNF‐α), is significantly upregulated in Nupr1‐deficient HECs, and the use of a specific TNF‐α neutralizing antibody partially reduces excessive HSPC generation in the explant cultures from Nupr1‐deficient embryos. This study identifies a novel negative regulator of EHT and the findings indicate that Nupr1 is a new potential target for future hematopoietic stem cell regeneration research. [ABSTRACT FROM AUTHOR]

Abstract: Aim: Thermal ablation therapy has recently emerged as a promising noninvasive treatment modality for localized solid malignancies. Except its direct tumor‐cell‐killing effect on local tumor tissues, the immunomodulatory effect has also long been noticed which too has substantial effect on clinical outcome, but it is complicated. Though much has been investigated and rich evidences have been achieved, the fundamental state and profile of immunomodulation by thermal ablation in cancer patients, its exact mechanism, especially the systematic mechanism, and its effect on antitumor immunity remain unclear. Methods: In this study, we dynamically monitored the immunomodulation by thermal ablation through combined analysis of peripheral lymphocyte populations, functional T cell subtype Th1 (CD3+CD4+IFN‐r+), Th2 (CD3+CD4+IL‐4+), Tc1 (CD3+CD8+IFN‐r+), Tc2 (CD3+CD8+IL‐4+) and mRNA expression of several immune‐active and ‐suppressive molecules including CD25, CD28, cytotoxic T‐lymphocyte‐associated protein 4, programmed cell death protein 1, Foxp3, transforming growth factor beta (TGF‐β) and interleukin (IL‐10) in 16 cancer patients. Results: The results show that local cancer thermal ablation modulated the cellular immunity characterized by obviously downregulation of regulatory T cells (Treg) and cytotoxicity T cells followed by CD4, CD8 and suppressor T cells (Ts), but upregulation of natural killer (NK) cells and mRNA expression of TGF‐β and IL‐10, suggesting a slight inhibition of the cellular immunity which may affect antitumor immunity. Conclusions: We suggest a further immunomodulation therapy after thermal therapy for recovering a Th1‐ and Tc1‐dominant immune response for pursuing a better long‐term antitumor immunity. [ABSTRACT FROM AUTHOR]

Intrahepatic cholangiocarcinoma (ICC) is the second most common liver malignancy. ICC typically features remarkable cellular heterogeneity and a dense stromal reaction. Therefore, a comprehensive understanding of cellular diversity and the interplay between malignant cells and niche cells is essential to elucidate the mechanisms driving ICC progression and to develop therapeutic approaches. Herein, we performed single-cell RNA sequencing (scRNA-seq) analysis on unselected viable cells from 8 human ICCs and adjacent samples to elucidate the comprehensive transcriptomic landscape and intercellular communication network. Additionally, we applied a negative selection strategy to enrich fibroblast populations in 2 other ICC samples to investigate fibroblast diversity. The results of the analyses were validated using multiplex immunofluorescence staining, bulk transcriptomic datasets, and functional in vitro and in vivo experiments. We sequenced a total of 56,871 single cells derived from human ICC and adjacent tissues and identified diverse tumor, immune, and stromal cells. Malignant cells displayed a high degree of inter-tumor heterogeneity. Moreover, tumor-infiltrating CD4 regulatory T cells exhibited highly immunosuppressive characteristics. We identified 6 distinct fibroblast subsets, of which the majority were CD146-positive vascular cancer-associated fibroblasts (vCAFs), with highly expressed microvasculature signatures and high levels of interleukin (IL)-6. Functional assays indicated that IL-6 secreted by vCAFs induced significant epigenetic alterations in ICC cells, particularly upregulating enhancer of zeste homolog 2 (EZH2) and thereby enhancing malignancy. Furthermore, ICC cell-derived exosomal miR-9-5p elicited high expression of IL-6 in vCAFs to promote tumor progression. Our single-cell transcriptomic dataset delineates the inter-tumor heterogeneity of human ICCs, underlining the importance of intercellular crosstalk between ICC cells and vCAFs, and revealing potential therapeutic targets. Intrahepatic cholangiocarcinoma is an aggressive and chemoresistant malignancy. Better understanding the complex transcriptional architecture and intercellular crosstalk of these tumors will help in the development of more effective therapies. Herein, we have identified important interactions between cancer cells and cancer-associated fibroblasts in the tumor stroma, which could have therapeutic implications. • Single cell transcriptomic datasets are a valuable resource to dissect cellular diversity and intercellular crosstalk of human ICCs. • Malignant cells displayed remarkable inter-tumor heterogeneity and Tregs revealed highly immunosuppressive characteristics. • Six distinct fibroblast subsets were defined in ICCs and adjacent tissues. • CD146+ vCAFs, comprising most of the fibroblasts, had tight interactions with malignant cells through IL-6/IL-6R axis. • Tumor exosomal miR-9-5p elicited IL-6 expression in vCAFs, contributing to ICC progression via upregulation of EZH2. [ABSTRACT FROM AUTHOR]

Generation of the first T lymphocytes in the human embryo involves the emergence, migration, and thymus seeding of lymphoid progenitors together with concomitant thymus organogenesis, which is the initial step to establish the entire adaptive immune system. However, the cellular and molecular programs regulating this process remain unclear. We constructed a single-cell transcriptional landscape of human early T lymphopoiesis by using cells from multiple hemogenic and hematopoietic sites spanning embryonic and fetal stages. Among heterogenous early thymic progenitors, one subtype shared common features with a subset of lymphoid progenitors in fetal liver that are known as thymus-seeding progenitors. Unbiased bioinformatics analysis identified a distinct type of pre-thymic lymphoid progenitors in the aorta-gonad-mesonephros (AGM) region. In parallel, we investigated thymic epithelial cell development and potential cell-cell interactions during thymus organogenesis. Together, our data provide insights into human early T lymphopoiesis that prospectively direct T lymphocyte regeneration, which might lead to development of clinical applications. • Single-cell RNA-seq resolves human early T lymphopoiesis and thymus organogenesis • The first ETPs in the thymus share transcriptional features of TSPs in human fetal liver • Pre-thymic lymphoid progenitors are transcriptomically identified in human AGM region • Cortical TECs mature earlier than medullary TECs in human thymic primordium A comprehensive and precise understanding of early T lymphopoiesis and thymus organogenesis in human embryo is lacking. By performing single-cell transcriptomic analysis on human embryonic and fetal hematopoietic organs, Zeng et al. reveal distinct subpopulations of early thymic progenitors, identify thymus-seeding progenitors in fetal liver and pre-thymic lymphoid progenitors in the aorta-gonad-mesonephros region, and characterize early development of thymic epithelial cells. [ABSTRACT FROM AUTHOR]

Undergoing endothelial-to-hematopoietic transition, a small fraction of embryonic aortic endothelial cells specializes into hemogenic endothelial cells (HECs) and eventually gives rise to hematopoietic stem cells (HSCs). Previously, we found that the activity of ribosome biogenesis (RiBi) is highly enriched in the HSC-primed HECs compared with adjacent arterial endothelial cells; however, whether RiBi is required in HECs for the generation of HSCs remains to be determined. Here, we have found that robust RiBi is markedly augmented during the endothelial-to-hematopoietic transition in mouse. Pharmacological inhibition of RiBi completely impeded the generation of HSCs in explant cultures. Moreover, disrupting RiBi selectively interrupted the HSC generation potential of HECs rather than T1 pre-HSCs, which was in line with its influence on cell cycle activity. Further investigation revealed that, upon HEC specification, the master transcription factor Runx1 dramatically bound to the loci of genes involved in RiBi, thereby facilitating this biological process. Taken together, our study provides functional evidence showing the indispensable role of RiBi in generating HSCs from HECs, providing previously unreported insights that may contribute to the improvement of HSC regeneration strategies., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Cervical squamous cell carcinoma (CESC) is a prototypical human cancer with well-characterized pathological stages of initiation and progression. However, high-resolution knowledge of the transcriptional programs underlying each stage of CESC is lacking, and important questions remain. We performed single-cell RNA sequencing of 76,911 individual cells from 13 samples of human cervical tissues at various stages of malignancy, illuminating the transcriptional tumorigenic trajectory of cervical epithelial cells and revealing key factors involved in CESC initiation and progression. In addition, we found significant correlations between the abundance of specific myeloid, lymphoid, and endothelial cell populations and the progression of CESC, which were also associated with patients' prognosis. Last, we demonstrated the tumor-promoting function of matrix cancer-associated fibroblasts via the NRG1-ERBB3 pathway in CESC. This study provides a valuable resource and deeper insights into CESC initiation and progression, which is helpful in refining CESC diagnosis and for the design of optimal treatment strategies.

Langerhans cell histiocytosis (LCH) is an inflammatory myeloid neoplasm caused by aberrant activation of the mitogen-activated protein kinase (MAPK) pathway. Circulating myeloid cells from patients often carry disease-associated mutations and can be differentiated into langerinhigh LCH-like cells in vitro, but their detailed immune-phenotypic and molecular profiles are lacking and could shed key insights into disease biology. Here we recruited 217 pediatric LCH patients and took blood and tissue samples for BRAFV600E analysis. Immune-phenotyping of the circulating Lin-HLA-DR+ immune population in 49 of these patients revealed that decreased frequency of plasmacytoid dendritic cells was significantly linked to disease severity. By single-cell RNA sequencing of samples from 14 patients, we identified key changes in expression of RAS-MAPK-extracellular signal-regulated kinase (ERK) signaling-related genes and transcription factors in distinct members of the mononuclear phagocyte system in the presence of BRAFV600E. Moreover, treatment of patients with the BRAF inhibitor dabrafenib resulted in MAPK cascade inhibition, inflammation prevention, and regulation of cellular metabolism within mononuclear phagocytes. Finally, we also observed elevated expression of RAS-MAPK-ERK signaling-related genes in a CD207+CD1a+ cell subcluster in skin. Taken together, our data extend the molecular understanding of LCH biology at single-cell resolution, which might contribute to improvement of clinical diagnostics and therapeutics, and aid in the development of personalized medicine approaches., (© 2021 by The American Society of Hematology.)

In the aorta-gonad-mesonephros (AGM) region of mouse embryos, pre-hematopoietic stem cells (pre-HSCs) are generated from rare and specialized hemogenic endothelial cells (HECs) via endothelial-to-hematopoietic transition, followed by maturation into bona fide hematopoietic stem cells (HSCs). As HECs also generate a lot of hematopoietic progenitors not fated to HSCs, powerful tools that are pre-HSC/HSC-specific become urgently critical. Here, using the gene knockin strategy, we firstly developed an Hlf-tdTomato reporter mouse model and detected Hlf-tdTomato expression exclusively in the hematopoietic cells including part of the immunophenotypic CD45 - and CD45 + pre-HSCs in the embryonic day (E) 10.5 AGM region. By in vitro co-culture together with long-term transplantation assay stringent for HSC precursor identification, we further revealed that unlike the CD45 - counterpart in which both Hlf-tdTomato-positive and negative sub-populations harbored HSC competence, the CD45 + E10.5 pre-HSCs existed exclusively in Hlf-tdTomato-positive cells. The result indicates that the cells should gain the expression of Hlf prior to or together with CD45 to give rise to functional HSCs. Furthermore, we constructed a novel Hlf-CreER mouse model and performed time-restricted genetic lineage tracing by a single dose induction at E9.5. We observed the labeling in E11.5 AGM precursors and their contribution to the immunophenotypic HSCs in fetal liver (FL). Importantly, these Hlf-labeled early cells contributed to and retained the size of the HSC pool in the bone marrow (BM), which continuously differentiated to maintain a balanced and long-term multi-lineage hematopoiesis in the adult. Therefore, we provided another valuable mouse model to specifically trace the fate of emerging HSCs during development., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Tang, He, Huang, Bai, Wang, Wang, Yang, Ni, Hou, Wang, Zhou, Yao, Gong, Hou, Liu and Lan.)

Hematopoietic stem cells (HSCs) are derived from hemogenic endothelial cells (HECs) during embryogenesis. The HSC-primed HECs increased to the peak at embryonic day (E) 10 and have been efficiently captured by the marker combination CD41 - CD43 - CD45 - CD31 + CD201 + Kit + CD44 + (PK44) in the aorta-gonad-mesonephros (AGM) region of mouse embryos most recently. In the present study, we investigated the spatiotemporal and functional heterogeneity of PK44 cells around the time of emergence of HSCs. First, PK44 cells in the E10.0 AGM region could be further divided into three molecularly different populations showing endothelial- or hematopoietic-biased characteristics. Specifically, with the combination of Kit, the expression of CD93 or CD146 could divide PK44 cells into endothelial- and hematopoietic-feature biased populations, which was further functionally validated at the single-cell level. Next, the PK44 population could also be detected in the yolk sac, showing similar developmental dynamics and functional diversification with those in the AGM region. Importantly, PK44 cells in the yolk sac demonstrated an unambiguous multilineage reconstitution capacity after in vitro incubation. Regardless of the functional similarity, PK44 cells in the yolk sac displayed transcriptional features different from those in the AGM region. Taken together, our work delineates the spatiotemporal characteristics of HECs represented by PK44 and reveals a previously unknown HSC competence of HECs in the yolk sac. These findings provide a fundamental basis for in-depth study of the different origins and molecular programs of HSC generation in the future., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Li, Gong, Hou, Huang, Wang, Liu, Ni, Wang, Wang, Hou, Yang, Yan, Zhang, Liu and Lan.)

Objective: Tumour heterogeneity represents a major obstacle to accurate diagnosis and treatment in gastric adenocarcinoma (GA). Here, we report a systematic transcriptional atlas to delineate molecular and cellular heterogeneity in GA using single-cell RNA sequencing (scRNA-seq)., Design: We performed unbiased transcriptome-wide scRNA-seq analysis on 27 677 cells from 9 tumour and 3 non-tumour samples. Analysis results were validated using large-scale histological assays and bulk transcriptomic datasets., Results: Our integrative analysis of tumour cells identified five cell subgroups with distinct expression profiles. A panel of differentiation-related genes reveals a high diversity of differentiation degrees within and between tumours. Low differentiation degrees can predict poor prognosis in GA. Among them, three subgroups exhibited different differentiation grade which corresponded well to histopathological features of Lauren's subtypes. Interestingly, the other two subgroups displayed unique transcriptome features. One subgroup expressing chief-cell markers (eg, LIPF and PGC ) and RNF43 with Wnt/β-catenin signalling pathway activated is consistent with the previously described entity fundic gland-type GA (chief cell-predominant, GA-FG-CCP). We further confirmed the presence of GA-FG-CCP in two public bulk datasets using transcriptomic profiles and histological images. The other subgroup specifically expressed immune-related signature genes (eg, LY6K and major histocompatibility complex class II) with the infection of Epstein-Barr virus. In addition, we also analysed non-malignant epithelium and provided molecular evidences for potential transition from gastric chief cells into MUC6 + TFF2 + spasmolytic polypeptide expressing metaplasia., Conclusion: Altogether, our study offers valuable resource for deciphering gastric tumour heterogeneity, which will provide assistance for precision diagnosis and prognosis., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Lead (Pb) exhibits serious adverse effects on the central nervous system, and the major pathogenic mechanism of Pb toxicity is oxidative stress. As one of the carotenoid family members with potent antioxidant properties, lycopene has shown its protections by inhibiting oxidative stress damage in numerous models of neurotoxicity. The current study was designed to explore the possible protective property in primary cultured rat hippocampal neurons challenged with Pb. We observed that 5 μM lycopene pretreatment for 4 h efficiently ameliorated Pb-caused damage in cell viability, accumulation of reactive oxygen species (ROS), and apoptosis in a dose-dependent manner. Moreover, lycopene (5 μM) attenuated the 50 μM Pb-induced mitochondrial ROS production, improved the activities of mitochondrial respiratory chain enzymes and ATP production, and ameliorated the 50 μM Pb-induced depolarization of mitochondrial membrane potential as well as opening of mitochondrial permeability transition pores. In addition, 5 μM lycopene restored the imbalance of Bax/Bcl-2, inhibited translocation of cytochrome c, and reduced caspase-3 activation. Taken together, these findings indicate that lycopene antagonizes against Pb-induced neurotoxicity and the underlying mechanism probably involves reduction of mitochondrial oxidative damage and mitochondria-mediated apoptosis., (© 2020 The Authors. MedComm published by Sichuan International Medical Exchange & Promotion Association (SCIMEA) and John Wiley & Sons Australia, Ltd.)

The functional heterogeneity of hematopoietic stem cells (HSCs) has been comprehensively investigated by single-cell transplantation assay. However, the heterogeneity regarding their physiological contribution remains an open question, especially for those with life-long hematopoietic fate of rigorous self-renewing and balanced differentiation capacities. In this study, we revealed that Procr expression was detected principally in phenotypical vascular endothelium co-expressing Dll4 and CD44 in the mid-gestation mouse embryos, and could enrich all the HSCs of the embryonic day 11.5 (E11.5) aorta-gonad-mesonephros (AGM) region. We then used a temporally restricted genetic tracing strategy to irreversibly label the Procr-expressing cells at E9.5. Interestingly, most labeled mature HSCs in multiple sites (such as AGM) around E11.5 were functionally categorized as lymphomyeloid-balanced HSCs assessed by direct transplantation. Furthermore, the labeled cells contributed to an average of 7.8% of immunophenotypically defined HSCs in E14.5 fetal liver (FL) and 6.9% of leukocytes in peripheral blood (PB) during one-year follow-up. Surprisingly, in aged mice of 24 months, the embryonically tagged cells displayed constant contribution to leukocytes with no bias to myeloid or lymphoid lineages. Altogether, we demonstrated, for the first time, the existence of a subtype of physiologically long-lived balanced HSCs as hypothesized, whose precise embryonic origin and molecular identity await further characterization., (Copyright © 2019 Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Ltd. All rights reserved.)

The generation of hematopoietic stem cells (HSCs) from embryonic endothelial precursors and pre-HSCs is precisely regulated by signaling pathways and transcription factors. Nevertheless, regulatory roles of non-coding RNAs remain unknown. Taking advantage of our ability to capture rare pre-HSCs and HSCs in vivo, we generated a single-cell landscape of long non-coding RNAs (lncRNAs) during HSC development. Combining bioinformatics and functional screening, we identified 6 lncRNAs influencing hematopoiesis in vitro. We further revealed that H19 lncRNA is pivotal for in vivo HSC emergence in aorta-gonads-mesonephros region. Early H19 lncRNA deficiency blocked endothelial-to-hematopoietic transition, which was independent of the H19-derived miR, miR-675. Moreover, H19-deficient pre-HSCs displayed promoter hypermethylation and concomitant downregulation of several master hematopoietic transcription factors, including Runx1 and Spi1. H19 deficiency increased the activity of S-adenosylhomocysteine hydrolase, a regulator of DNA methylation, which partially contributed to the observed hematopoietic defect. Our findings provide a resource for further analysis of lncRNAs in embryonic HSC development., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Aim: Thermal ablation therapy has recently emerged as a promising noninvasive treatment modality for localized solid malignancies. Except its direct tumor-cell-killing effect on local tumor tissues, the immunomodulatory effect has also long been noticed which too has substantial effect on clinical outcome, but it is complicated. Though much has been investigated and rich evidences have been achieved, the fundamental state and profile of immunomodulation by thermal ablation in cancer patients, its exact mechanism, especially the systematic mechanism, and its effect on antitumor immunity remain unclear., Methods: In this study, we dynamically monitored the immunomodulation by thermal ablation through combined analysis of peripheral lymphocyte populations, functional T cell subtype Th1 (CD3+CD4+IFN-r+), Th2 (CD3+CD4+IL-4+), Tc1 (CD3+CD8+IFN-r+), Tc2 (CD3+CD8+IL-4+) and mRNA expression of several immune-active and -suppressive molecules including CD25, CD28, cytotoxic T-lymphocyte-associated protein 4, programmed cell death protein 1, Foxp3, transforming growth factor beta (TGF-β) and interleukin (IL-10) in 16 cancer patients., Results: The results show that local cancer thermal ablation modulated the cellular immunity characterized by obviously downregulation of regulatory T cells (Treg) and cytotoxicity T cells followed by CD4, CD8 and suppressor T cells (Ts), but upregulation of natural killer (NK) cells and mRNA expression of TGF-β and IL-10, suggesting a slight inhibition of the cellular immunity which may affect antitumor immunity., Conclusions: We suggest a further immunomodulation therapy after thermal therapy for recovering a Th1- and Tc1-dominant immune response for pursuing a better long-term antitumor immunity., (© 2018 John Wiley & Sons Australia, Ltd.)

Immune checkpoint inhibitors that block the PD-1/PD-L1 signaling pathway have been used to treat a wide variety of cancers. Although results have been promising, significant inter-individual and inter-tumor variability has been observed. It is believed that better clinical outcome could be achieved if the treatment was individually designed based on the functional status of the PD-1/PD-L1 signaling and the cellular immunity. In this study, we analyzed the mRNA expression of PD-1 and other immunomodulatory genes in peripheral blood from cancer patients, and immunomodulatory gene expression during radiotherapy and immunomodulation therapy with cytokines. Our results show that the PD-1 mRNA expression is significantly increased in peripheral blood in cancer patients. Anti-cancer treatments can significantly modulate the PD-1 expression, but this is largely dependent on the initial immune status. Moreover, the PD-1 expression on peripheral lymphocytes can be immunoactivation-derived. These results suggest that the regulation and expression pattern of PD-1/PD-L1 signal is complicated which will influence the effect of blockade of the PD-1/PD-L1 signaling pathway for cancer treatment. Through combined analysis of PD-1, CTLA-4, and other immune markers in peripheral blood, we may accurately evaluate the functional status of PD-1/PD-L1 signaling and cellular immunity, thereby providing clues for guiding anti-PD-1 or anti-PD-L1 treatment., Competing Interests: CONFLICTS OF INTEREST All authors have no potential conflicts of interest.

Recent progress by versatile approaches supports the new hypothesis that multi-potent hematopoietic stem cells (HSCs) are directly formed from a rare population of endothelial cells in mid-gestation mouse embryos. This process is therefore known as the endothelial-to-hematopoietic transition (EHT). Nevertheless, there is no functional evidence that documents the HSC transition from purified endothelial cells. In this study, we developed an OP9-DL1-based co-culture system that was able to facilitate the HSC specification and/or expansion in vitro of mouse embryonic day 10.5 (E10.5) Tie2(+) cells remarkably. Then, the immunophenotypically defined endothelial cells were harvested by a combination of surface markers (Flk1(+)CD31(+)CD41(-)CD45(-)Ter119(-)) from the caudal half of E10.0-E11.0 mouse embryos. The transplantation of the endothelia/OP9-DL1 co-cultures led to long-term, high-level, multi-lineage, and multi-organ hematopoietic reconstitution in the irradiated adult recipients. The induced HSC activity was initially observed at E10.5, and a significant increase was detected at E11.0, which suggests a temporally specific regulation. Taken together, for the first time, we provide functional evidence showing the HSC potential of purified embryonic endothelial cells, which is indispensable for the emerging EHT concept. Moreover, the newly defined co-culture system will aid the exploration of the key molecules governing the HSC transition from embryonic and even postnatal endothelial cells, which has enormous significance in basic and translational research., (Copyright © 2013. Published by Elsevier Ltd.)

Spinal cord injury and regeneration involves transcriptional activity of many genes, of which many remain unknown. Using the rat spinal cord full- transection model, bioinformatics, cloning, expression assays, fusion proteins, and transfection techniques, we identified and characterized one such differentially expressed gene, termed scirr1 (spinal cord injury and/or regeneration related gene 1). Fourteen orthologs were found in 13 species from echinoderm to insect and human by Blast search of NCBI protein reference sequence database. However, no further information is available for these homologues. Using whole-mount in situ hybridization, mouse scirr1 mRNA was expressed temporally and spatially in accordance with the early development sequence of the central nervous system. In adult rat spinal cord, expression of scirr1 mRNA was localized to neurons of gray matter by in situ hybridization. Using immunohistochemistry, SCIRR1 protein was found to be up-regulated and expressed more highly in spinal cord neurons farther from the epicenter of injury. Although the precise function of SCIRR1 is unknown, its unique pattern of expression during CNS early development and up-regulation after spinal cord injury suggest that SCIRR1 should be involved in the succeeding injury and/or repair processes of the injured spinal cord. Also, the typical F-box and leucine-rich repeat (LRR) architecture of rat SCIRR1 indicated that it may play an important substrate recruiting role in the pleiotropic ubiquitin/proteasome pathway. All these make scirr1 a new interesting start to study the spinal cord injury and regeneration mechanism.