Guiding T lymphopoiesis from pluripotent stem cells by defined transcription factors

Disrupting Notch signaling related HES1 in myeloid cells reinvigorates antitumor T cell responses

BACKGROUND

Tumor-associated macrophages (TAMs) are immunosuppressive cells within the tumor microenvironment (TME) that hinder anti-tumor immunity. Notch signaling is a pathway crucial for TAM differentiation and function. Here, we investigate the role of HES1, a downstream target of Notch signaling, in TAM-mediated immunosuppression and explore its potential as a target for cancer immunotherapy.

METHODS

In this work, we constructed conditional Hes1 knockout mice to selectively delete Hes1 in TAMs. We further analyzed the TME composition, T cell infiltration and activation, and anti-tumor effects in these mice, both alone and in combination with PD-1 checkpoint blockade.

RESULTS

Our study showed that expression levels of Notch target Hes1 were increase in TAMs and mice with conditional knockout of Hes1 gene in TAMs exhibited decreased tumor growth, with increased infiltration and activation of cytotoxic T cells in tumors. Expression of tumor promoting factors was critically altered in Hes1-conditional KO TAMs, leading to the improved tumor microenvironment. Notably, arginase-1 expression was decreased in Hes1-conditional KO mice. Arg1 is known to deplete arginine and deactivate T cells in the TME. Administration of anti-PD-1 monoclonal antibody inhibited tumor growth to a greater extent in Hes1-conditional KO mice than in WT mice.

CONCLUSIONS

We identified a pivotal role for the Notch signaling pathway in shaping TAM function, suggesting that T-cell dysfunction in the TME is caused when the Notch target, HES1, in TAMs is upregulated by tumor-associated factors (TAFs), which, in turn, increases the expression of arginase-1. Targeting HES1 in TAMs appears to be a promising strategy for cancer immunotherapy.

Updates in novel immunotherapeutic strategies for relapsed/refractory AML

Acute myeloid leukemia (AML) is a severe hematological malignancy with poor outcomes, particularly in older adults. Traditional treatment options like high-dose chemotherapy often lead to refractory or relapsed AML, with even worse outcomes. New therapies for relapsed and refractory AML are needed, and this review explores the most recent advancements in immunotherapy in AML. Checkpoint Inhibitors utilizing innate or adaptive immune targeting have shown potential to improve AML outcomes when combined with hypomethylating agents and chemotherapy. The use of adoptive cell therapy in AML demonstrates promising early data, however, there is a need for better target selection. Although early in development, both vaccine therapy as well as stimulator of interferon genes (STING) agonists have potential to enhance the innate immune response to overcome AML's immune evasion. Immunotherapy has become a promising approach for AML treatment, especially in refractory and relapsed AML, especially in patients who are not eligible for allogeneic stem cell transplants. Future research should focus on a deeper understanding of the immune microenvironment to identify the most critical targets for optimization, as well as personalized therapeutic combination strategies. Here we present a comprehensive overview of the recent developments in immunotherapy for relapsed and refractory AML.

Sensing and guiding cell-state transitions by using genetically encoded endoribonuclease-mediated microRNA sensors

Precisely sensing and guiding cell-state transitions via the conditional genetic activation of appropriate differentiation factors is challenging. Here we show that desired cell-state transitions can be guided via genetically encoded sensors, whereby endogenous cell-state-specific miRNAs regulate the translation of a constitutively transcribed endoribonuclease, which, in turn, controls the translation of a gene of interest. We used this approach to monitor several cell-state transitions, to enrich specific cell types and to automatically guide the multistep differentiation of human induced pluripotent stem cells towards a haematopoietic lineage via endothelial cells as an intermediate state. Such conditional activation of gene expression is durable and resistant to epigenetic silencing and could facilitate the monitoring of cell-state transitions in physiological and pathological conditions and eventually the 'rewiring' of cell-state transitions for applications in organoid-based disease modelling, cellular therapies and regenerative medicine.

Dysregulated T-cell homeostasis and decreased CD30+ Treg proliferating in aplastic anemia

Aplastic anemia (AA) is an autoimmune hematopoietic disease mediated by autoreactive T cells leading to bone marrow failure. However, the precise role of autoreactive T cells in the development of AA is not fully understood, hindering the advancement of therapeutic and diagnostic strategies. In this study, we conducted a single-cell transcriptome analysis of CD8+ T cells, conventional CD4+ T (CD4+ Tconv) cells, and Treg cells, to elucidate the potential disruption of T cell homeostasis in patients with AA. We identified changes in CD4+ Tconv cells, including loss of homeostasis in naïve and memory cells and increased differentiation potential in T helper type 1 (TH1), T helper type 2 (TH2), and T helper type 17 (TH17) cells. Additionally, we identified naïve and memory CD8+ T cells that were enforced into an effector state. CD127 is an ideal surface marker for assessing the immune state of CD8+ T cells，as identified by flow cytometry. Abnormal expression of TNFSF8 has been observed in AA and other autoimmune diseases. Flow cytometry analysis revealed that TNFRSF8 (CD30), a receptor for TNFSF8, was predominantly present in human Treg cells. Importantly, patients with AA have a decreased CD30+ Treg subset. RNA-sequencing analysis revealed, that the CD30+ Treg cells are characterized by high proliferation and a remarkable immunosuppressive phenotype. Taken, together, we propose that abnormal TNFSF8/TNFRSF8 signaling is involved in dysfunctional T cell immunity by increasing the destruction of CD30+ Treg cells.

A culture method with berbamine, a plant alkaloid, enhances CAR-T cell efficacy through modulating cellular metabolism

Memory T cells demonstrate superior in vivo persistence and antitumor efficacy. However, methods for manufacturing less differentiated T cells are not yet well-established. Here, we show that producing chimeric antigen receptor (CAR)-T cells using berbamine (BBM), a natural compound found in the Chinese herbal medicine Berberis amurensis, enhances the antitumor efficacy of CAR-T cells. BBM is identified through cell-based screening of chemical compounds using induced pluripotent stem cell-derived T cells, leading to improved viability with a memory T cell phenotype. Transcriptomics and metabolomics using stem cell memory T cells reveal that BBM broadly enhances lipid metabolism. Furthermore, the addition of BBM downregulates the phosphorylation of p38 mitogen-activated protein kinase and enhanced mitochondrial respiration. CD19-CAR-T cells cultured with BBM also extend the survival of leukaemia mouse models due to their superior in vivo persistence. This technology offers a straightforward approach to enhancing the antitumor efficacy of CAR-T cells.

Selecting Monoclonal Cell Lineages from Somatic Reprogramming Using Robotic-Based Spatial-Restricting Structured Flow

Somatic cell reprogramming generates induced pluripotent stem cells (iPSCs), which serve as a crucial source of seed cells for personalized disease modeling and treatment in regenerative medicine. However, the process of reprogramming often causes substantial lineage manipulations, thereby increasing cellular heterogeneity. As a consequence, the process of harvesting monoclonal iPSCs is labor-intensive and leads to decreased reproducibility. Here, we report the first in-house developed robotic platform that uses a pin-tip-based micro-structure to manipulate radial shear flow for automated monoclonal iPSC colony selection (~1 s) in a non-invasive and label-free manner, which includes tasks for somatic cell reprogramming culturing, medium changes; time-lapse-based high-content imaging; and iPSCs monoclonal colony detection, selection, and expansion. Throughput-wise, this automated robotic system can perform approximately 24 somatic cell reprogramming tasks within 50 days in parallel via a scheduling program. Moreover, thanks to a dual flow-based iPSC selection process, the purity of iPSCs was enhanced, while simultaneously eliminating the need for single-cell subcloning. These iPSCs generated via the dual processing robotic approach demonstrated a purity 3.7 times greater than that of the conventional manual methods. In addition, the automatically produced human iPSCs exhibited typical pluripotent transcriptional profiles, differentiation potential, and karyotypes. In conclusion, this robotic method could offer a promising solution for the automated isolation or purification of lineage-specific cells derived from iPSCs, thereby accelerating the development of personalized medicines.

Targeted single-cell RNA sequencing analysis reveals metabolic reprogramming and the ferroptosis-resistant state in hematologic malignancies

Hematologic malignancies are the most common hematopoietic diseases and a major public health concern. However, the mechanisms underlying myeloid tumors remain unknown owing to the intricate interplay between mutations and diverse clonal evolution patterns, as evidenced by the analysis of bulk cell-derived omics data. Several single-cell omics techniques have been used to characterize the hierarchies and altered immune microenvironments of hematologic malignancies. The comprehensive single-cell atlas of hematologic malignancies provides novel opportunities for personalized combinatorial targeted treatments, avoiding unwanted chemo-toxicity. In the present study, we performed transcriptome sequencing by combining single-cell RNA sequencing (scRNA-seq) with a targeted oncogenic gene panel for acute myeloid leukemia, overcoming the limitations of scRNA-seq in detecting oncogenic mutations. The distribution of oncogenic IDH1, IDH2, and KRAS mutations in each cell type was identified in the bone marrow (BM) samples of each patient. Our findings suggest that ferroptosis and metabolic reprogramming are involved in the tumorigenesis and chemotherapy resistance of oncogenic mutation-carrying cells. Biological progression via IDH1, IDH2, and KRAS mutations arrests hematopoietic maturation. Our study findings provide a rationale for using primary BM cells for personalized treatment in clinical settings.

Generating hematopoietic cells from human pluripotent stem cells: approaches, progress and challenges

Human pluripotent stem cells (hPSCs) have been suggested as a potential source for the production of blood cells for clinical application. In two decades, almost all types of blood cells can be successfully generated from hPSCs through various differentiated strategies. Meanwhile, with a deeper understanding of hematopoiesis, higher efficiency of generating progenitors and precursors of blood cells from hPSCs is achieved. However, how to generate large-scale mature functional cells from hPSCs for clinical use is still difficult. In this review, we summarized recent approaches that generated both hematopoietic stem cells and mature lineage cells from hPSCs, and remarked their efficiency and mechanisms in producing mature functional cells. We also discussed the major challenges in hPSC-derived products of blood cells and provided some potential solutions. Our review summarized efficient, simple, and defined methodologies for developing good manufacturing practice standards for hPSC-derived blood cells, which will facilitate the translation of these products into the clinic.

CCL17 acts as an antitumor chemokine in micromilieu‐driven immune skewing

BACKGROUND

Chemokines are critical players in the local immune responses to tumors. CCL17 (thymus and activation-regulated chemokine, TARC) and CCL22 (macrophage-derived chemokine, MDC) can attract CCR4-bearing cells involving the immune landscape of cancer. However, their direct roles and functional states in tumors remain largely unclear.

METHODS

We analyzed the lymphoma-related scRNA-seq and bulk RNA-seq datasets and identified the CCL17/CCL22-CCR4 axis as the unique participant of the tumor microenvironment. Then we edited the A20 lymphoma cell line to express CCL17 and CCL22 and assessed their function using three mouse models (Balb/C mouse, Nude mouse, and NSG mouse). In addition, we retrospectively checked the relationship between the CCL17/CCL22-CCR4 axis and the survival rates of cancer patients.

RESULTS

The active CCL17/CCL22-CCR4 axis is a distinctive feature of the Hodgkin lymphoma microenvironment. CCR4 is widely expressed in immune cells but highly exists on the surface of NK, NKT, and Treg cells. The tumor model of Balb/C mice showed that CCL17 acts as an anti-tumor chemokine mediated by activated T cell response. In addition, the tumor model of Nude mice showed that CCL17 recruits NK cells for inhibiting lymphoma growth and enhances the NK-cDC1 interaction for resisting IL4i1-mediated immunosuppression. Interestingly, CCL17-mediated antitumor immune responses depend on lymphoid lineages but not mainly myeloid ones. Furthermore, we found CCL17/CCL22-CCR4 axis cannot be regarded as biomarkers of poor prognosis in most cancer types from the TCGA database.

CONCLUSION

We provided direct evidence of antitumor functions of CCL17 mediated by the recruitment of conventional T cells, NKT cells, and NK cells. Clinical survival outcomes of target gene (CCL17, CCL22, and CCR4) expression also identified that CCL17/CCL22-CCR4 axis is not a marker of poor prognosis.

Transcription factor Nkx2-3 maintains the self-renewal of hematopoietic stem cells by regulating mitophagy

Hematopoietic stem cells (HSCs) reside at the top of the hematopoietic hierarchy, exhibiting a unique capacity to self-renew and differentiate into all blood cells throughout the lifetime. However, how to prevent HSC exhaustion during long-term hematopoietic output is not fully understood. Here, we show that the homeobox transcription factor Nkx2-3 is required for HSC self-renewal by preserving metabolic fitness. We found that Nkx2-3 is preferentially expressed in HSCs with excessive regenerative potential. Mice with conditional deletion of Nkx2-3 displayed a reduced HSC pool and long-term repopulating capacity as well as increased sensitivity to irradiation and 5-flurouracil treatment due to impaired HSC quiescence. In contrast, overexpression of Nkx2-3 improved HSC function both in vitro and in vivo. Furthermore, mechanistic studies revealed that Nkx2-3 can directly control the transcription of the critical mitophagy regulator ULK1, which is essential for sustaining metabolic homeostasis in HSCs by clearing activated mitochondria. More importantly, a similar regulatory role of NKX2-3 was observed in human cord blood-derived HSCs. In conclusion, our data demonstrate an important role of the Nkx2-3/ULK1/mitophagy axis in regulating the self-renewal of HSCs, therefore providing a promising strategy to improve the function of HSCs in the clinic.

Prolonged generation of multi-lineage blood cells in wild-type animals from pluripotent stem cells

Regenerating prolonged multi-lineage hematopoiesis from pluripotent stem cells (PSCs), an unlimited cell source, is a crucial aim of regenerative hematology. In this study, we used a gene-edited PSC line and revealed that simultaneous expression of three transcription factors, Runx1, Hoxa9, and Hoxa10, drove the robust emergence of induced hematopoietic progenitor cells (iHPCs). The iHPCs engrafted successfully in wild-type animals and repopulated abundant and complete myeloid-, B-, and T-lineage mature cells. The generative multi-lineage hematopoiesis distributed normally in multiple organs, persisted over 6 months, and eventually declined over time with no leukemogenesis. Transcriptome characterization of generative myeloid, B, and T cells at the single-cell resolution further projected their identities to natural cell counterparts. Thus, we provide evidence that co-expression of exogenous Runx1, Hoxa9, and Hoxa10 simultaneously leads to long-term reconstitution of myeloid, B, and T lineages using PSC-derived iHPCs as the cell source.

Multi-modular structure of the gene regulatory network for specification and commitment of murine T cells

T cells develop from multipotent progenitors by a gradual process dependent on intrathymic Notch signaling and coupled with extensive proliferation. The stages leading them to T-cell lineage commitment are well characterized by single-cell and bulk RNA analyses of sorted populations and by direct measurements of precursor-product relationships. This process depends not only on Notch signaling but also on multiple transcription factors, some associated with stemness and multipotency, some with alternative lineages, and others associated with T-cell fate. These factors interact in opposing or semi-independent T cell gene regulatory network (GRN) subcircuits that are increasingly well defined. A newly comprehensive picture of this network has emerged. Importantly, because key factors in the GRN can bind to markedly different genomic sites at one stage than they do at other stages, the genes they significantly regulate are also stage-specific. Global transcriptome analyses of perturbations have revealed an underlying modular structure to the T-cell commitment GRN, separating decisions to lose "stem-ness" from decisions to block alternative fates. Finally, the updated network sheds light on the intimate relationship between the T-cell program, which depends on the thymus, and the innate lymphoid cell (ILC) program, which does not.

Antigen-specific TCR-T cells from Rag2 gene-deleted pluripotent stem cells impede solid tumour growth in a mouse model

The technology of adoptive transfer of T-cell receptor (TCR) engineered T cells is wildly investigated as it has the potential to treat solid cancers. However, the therapeutic application of TCR-T cells is hampered by the poor quality derived mainly from patients' peripheral blood, as well as heterogeneous TCRs caused by the mismatch between transgenic and endogenous TCRs. To improve the homogeneity, antigen-specificity and reduce possible autoreactivity, here we developed a technique to generate antigen-specific T cells from Rag2 gene-deleted pluripotent stem cells (PSCs) and further measured their anti-tumour efficacy. PSCs were first targeted with OT1 TCR into the Rag2 locus to prevent TCR rearrangement during T-cell development. The engineered PSCs were then differentiated through a two-step strategy, in vitro generation of haematopoietic progenitor cells, and in vivo development and maturation of TCR-T cells. Finally, the response to tumour cells was assessed in vitro and in vivo. The regenerated OT1-iT displayed monoclonal antigen-specific TCR expression, and phonotypic normalities in the spleen and lymph node tissues. Importantly, the OT1-iT cells eliminated tumour cells while releasing specific cytokines in vitro. Furthermore, adoptive transfer of OT1-iT cells suppresses solid tumour growth in tumour-bearing animals. Our study presents a novel and straightforward strategy for producing antigen-specific TCR-T cells in vivo from PSCs, allowing for allogeneic transplantation and therapy of solid tumours.

Current status of producing autologous hematopoietic stem cells

Hematopoietic stem cells (HSCs) transplantation is an established therapy for many diseases of the hematopoietic system, for example aplastic anemia, acute myeloid leukemia and acute lymphoblastic leukemia. With the development of the HSCs research, HSCs provide an attractive method for treating hereditary blood disorders and immunotherapy of cancer by introducing gene modification. Compared with allogenic HSCs transplantation, using autologous HSCs or HSCs from induced pluripotent stem cells (iPSCs) would eliminate the probability of alloimmunization and transfusion-transmitted infectious diseases. The methods for obtaining autologous HSCs include amplifying patients' HSCs or inducing patients' somatic cells to HSCs (graph abstract). However, the biggest problem is inducing HSCs to proliferate in vitro and maintaining their stemness at the same time. Although many tests have been made to transform iPSCs to HSCs, the artificially generated HSCs still have substantial disparity compared with physiological HSCs. This review summarized the application status and obstacles to implantation of autologous HSCs and iPSC-derived HSCs. Meanwhile, we summarized the latest research progress in HSCs amplification and iPSCs reprogramming methods, which will help to solve the problems mentioned above.

The CXCR4-CXCL12 axis promotes T cell reconstitution via efficient hematopoietic immigration

T cells play a critical role in immunity to protect against pathogens and malignant cells. T cell immunodeficiency is detrimental, especially when T cell perturbation occurs during severe infection, irradiation, chemotherapy, and age-related thymic atrophy. Therefore, strategies that enhance T cell reconstitution provide considerable benefit and warrant intensive investigation. Here, we report the construction of a T cell ablation model in Tg(coro1a:DenNTR) zebrafish via metronidazole administration. The nascent T cells are mainly derived from the hematopoietic cells migrated from the kidney, the functional homolog of bone marrow and the complete recovery time is 6.5 days post-treatment. The cxcr4b gene is upregulated in the responsive hematopoietic cells. Functional interference of CXCR4 via both genetic and chemical manipulations does not greatly affect T lymphopoiesis, but delays T cell regeneration by disrupting hematopoietic migration. In contrast, cxcr4b accelerates the replenishment of hematopoietic cells in the thymus. Consistently, Cxcl12b, a ligand of Cxcr4, is increased in the thymic epithelial cells of the injured animals. Decreased or increased expression of Cxcl12b results in compromised or accelerated T cell recovery, respectively, similar to those observed with Cxcr4b. Taken together, our study reveals a role of CXCR4-CXCL12 signaling in promoting T cell recovery and provides a promising target for the treatment of immunodeficiency due to T cell injury.

Reprogramming cell fates towards novel cancer immunotherapies

Recent advances in our understanding of host immune and cancer cells interactions have made immunotherapy a prominent choice in cancer treatment. Despite such promise, cell-based immunotherapies remain inapplicable to many patients due to severe limitations in the availability and quality of immune cells isolated from donors. Reprogramming technologies that facilitate the engineering of cell types of interest, are emerging as a putative solution to such challenges. Here we focus on the recent progress being made in reprogramming technologies with respect to the immune system and their potential for clinical applications.

Quantitative analysis of nutrients for nucleosides, nucleobases and amino acids hidden behind five distinct regions-derived Poria cocos using ultra-performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry

Poria cocos is an edible fungus used as a health product and traditional Chinese medicinal preparation. Nevertheless, little is known about its nutrients. In this study, ultra-high performance liquid chromatography coupled with triple-quadrupole linear ion-trap tandem mass spectrometry was conducted to quantify nucleosides, nucleobases, and amino acids in 32 batches of Poria cocos samples collected from Anhui, Sichuan, Hubei, Hunan and Guizhou. Subsequently, the linearity, precision, repeatability, stability, and recovery of our methods were validated. Samples from different regions were clearly separated by partial least squares discriminant analysis and cluster analysis. Our results suggested that Poria cocos samples from different geographical environments differed in nucleosides, nucleobases, and amino acids. The plot of variable importance for projection disclosed differential compositions of L-Leucine, Uridine, L-Asparagine, L-Glutamine, L-phenylalanine, L-Ornithine monohydrochloride, L-Hydroxyproline, Taurine and Inosine in Poria cocos from five regions. We found the highest content of total analytes, total amino acids and total non-essential amino acids in Poria cocos from Anhui, total essential amino acids in the Sichuan samples and total nucleosides in Hunan samples. Overall, we determined the content of Poria cocos-derived nucleosides, nucleobases, and amino acids, providing the foothold for further chemical mining and use of Poria cocos. This article is protected by copyright. All rights reserved.

Hematopoietic Stem Cells and Regeneration

Hematopoietic stem cell (HSC) regeneration is the remarkable process by which extremely rare, normally inactive cells of the bone marrow can replace an entire organ if called to do so by injury or harnessed by transplantation. HSC research is arguably the first quantitative single-cell science and the foundation of adult stem cell biology. Bone marrow transplant is the oldest and most refined technique of regenerative medicine. Here we review the intertwined history of the discovery of HSCs and bone marrow transplant, the molecular and cellular mechanisms of HSC self-renewal, and the use of HSCs and their derivatives for cell therapy.

Generation and clinical potential of functional T lymphocytes from gene-edited pluripotent stem cells

Engineered T cells have been shown to be highly effective in cancer immunotherapy, although T cell exhaustion presents a challenge for their long-term function. Additional T-cell sources must be exploited to broaden the application of engineered T cells for immune defense and reconstitution. Unlimited sources of pluripotent stem cells (PSCs) have provided a potential opportunity to generate precise-engineered therapeutic induced T (iT) cells. Single-cell transcriptome analysis of PSC-derived induced hematopoietic stem and progenitor cells (iHSPC)/iT identified the developmental pathways and possibilities of generating functional T cell from PSCs. To date, the PSC-to-iT platforms encounter several problems, including low efficiency of conventional T subset specification, limited functional potential, and restrictions on large-scale application, because of the absence of a thymus-like organized microenvironment. The updated PSC-to-iT platforms, such as the three-dimensional (3D) artificial thymic organoid (ATO) co-culture system and Runx1/Hoxa9-enforced iT lymphopoiesis, provide fresh perspectives for coordinating culture conditions and transcription factors, which may greatly improve the efficiency of T-cell generation greatly. In addition, the improved PSC-to-iT platform coordinating gene editing technologies will provide various functional engineered unconventional or conventional T cells. Furthermore, the clinical applications of PSC-derived immune cells are accelerating from bench to bedside.

Engineering complexity in human tissue models of cancer

Major progress in the understanding and treatment of cancer have tremendously improved our knowledge of this complex disease and improved the length and quality of patients' lives. Still, major challenges remain, in particular with respect to cancer metastasis which still escapes effective treatment and remains responsible for 90% of cancer related deaths. In recent years, the advances in cancer cell biology, oncology and tissue engineering converged into the engineered human tissue models of cancer that are increasingly recapitulating many aspects of cancer progression and response to drugs, in a patient-specific context. The complexity and biological fidelity of these models, as well as the specific questions they aim to investigate, vary in a very broad range. When selecting and designing these experimental models, the fundamental question is "how simple is complex enough" to accomplish a specific goal of cancer research. Here we review the state of the art in developing and using the human tissue models in cancer research and developmental drug screening. We describe the main classes of models providing different levels of biological fidelity and complexity, discuss their advantages and limitations, and propose a framework for designing an appropriate model for a given study. We close by outlining some of the current needs, opportunities and challenges in this rapidly evolving field.

Co-Expression of Runx1, Hoxa9, Hlf, and Hoxa7 Confers Multi-Lineage Potential on Hematopoietic Progenitors Derived From Pluripotent Stem Cells

The intrinsic factors that determine the fundamental traits of engraftment ability and multi-lineage potential of hematopoietic stem cells (HSCs) remain elusive. The induction of bona fade HSCs from pluripotent stem cells (PSCs) in dishes is urgently demanded but remains a great challenge in translational medicine. Runx1, Hoxa9, Hlf, and Hoxa7 are developmentally co-expressed during endothelial-to-hematopoietic transition and adult haematopoiesis. However, the expression of these factors fails to be turned on during in vitro hematopoietic induction from PSCs. Here, we established an inducible gene over-expression embryonic stem cell (ESC) line in which exogenous Runx1, Hoxa9, Hlf, and Hoxa7 genes were tandemly knocked in. A population of induced hematopoietic progenitor cells (iHPCs) expressing Kit and Sca1 surface markers were successfully obtained in vitro from the gene edited-ESC line. Upon transplantation of the Runx1-Hoxa9-Hlf-Hoxa7 ESC-derived iHPCs into irradiated immunodeficient mice, they can dominantly contribute to B cells, low proportions of T cells and myeloid cells. However, Runx1-Hoxa9-Hlf ESC-derived iHPCs only produced B lineage cells with extremely low contributions. Our study unveils that the coordination of Runx1, Hoxa9, Hlf, and Hoxa7 led to generation of the hematopoietic progenitors with the capacity of multi-lineage hematopoietic reconstitution in the immunodeficient recipient mice.

Regeneration of immunocompetent B lymphopoiesis from pluripotent stem cells guided by transcription factors

Regeneration of functional B lymphopoiesis from pluripotent stem cells (PSCs) is challenging, and reliable methods have not been developed. Here, we unveiled the guiding role of three essential factors, Lhx2, Hoxa9, and Runx1, the simultaneous expression of which preferentially drives B lineage fate commitment and in vivo B lymphopoiesis using PSCs as a cell source. In the presence of Lhx2, Hoxa9, and Runx1 expression, PSC-derived induced hematopoietic progenitors (iHPCs) immediately gave rise to pro/pre-B cells in recipient bone marrow, which were able to further differentiate into entire B cell lineages, including innate B-1a, B-1b, and marginal zone B cells, as well as adaptive follicular B cells. In particular, the regenerative B cells produced adaptive humoral immune responses, sustained antigen-specific antibody production, and formed immune memory in response to antigen challenges. The regenerative B cells showed natural B cell development patterns of immunoglobulin chain switching and hypermutation via cross-talk with host T follicular helper cells, which eventually formed T cell-dependent humoral responses. This study exhibits de novo evidence that B lymphopoiesis can be regenerated from PSCs via an HSC-independent approach, which provides insights into treating B cell-related deficiencies using PSCs as an unlimited cell resource.

Single-Cell Analysis of Target Antigens of CAR-T Reveals a Potential Landscape of "On-Target, Off-Tumor Toxicity"

Cellular immunotherapy represented by CD19-directed chimeric antigen receptor T (CAR-T) cells has achieved great success in recent years. An increasing number of CAR-T therapies are being developed for cancer treatment, but the frequent and varied adverse events, such as “on-target, off-tumor toxicity”, limit CAR-T application. Here, we identify the target antigen expression patterns of CAR therapies in 18 tissues and organs (peripheral blood mononuclear cells, bone marrow, lymph nodes, spleen, heart, ascending aortic tissue, trachea, lung, skin, kidney, bladder, esophagus, stomach, small intestine, rectum, liver, common bile duct, and pancreas) from healthy human samples. The atlas determines target antigens expressed on some normal cell types, which facilitates elucidating the cause of “on-target, off-tumor toxicity” in special tissues and organs by targeting some antigens, but not others. Moreover, we describe the target antigen expression patterns of B-lineage-derived malignant cells, acute myeloid leukemia (AML), and solid tumors. Overall, the present study indicates the pathogenesis of “on-target, off-tumor toxicity” during CAR therapies and provides guidance on taking preventive measures during CAR treatment.

Hematopoietic Cells from Pluripotent Stem Cells: Hope and Promise for the Treatment of Inherited Blood Disorders

Inherited blood disorders comprise a large spectrum of diseases due to germline mutations in genes with key function in the hematopoietic system; they include immunodeficiencies, anemia or metabolic diseases. For most of them the only curative treatment is bone marrow transplantation, a procedure associated to severe complications; other therapies include red blood cell and platelet transfusions, which are dependent on donor availability. An alternative option is gene therapy, in which the wild-type form of the mutated gene is delivered into autologous hematopoietic stem cells using viral vectors. A more recent therapeutic perspective is gene correction through CRISPR/Cas9-mediated gene editing, that overcomes safety concerns due to insertional mutagenesis and allows correction of base substitutions in large size genes difficult to incorporate into vectors. However, applying this technique to genomic disorders caused by large gene deletions is challenging. Chromosomal transplantation has been proposed as a solution, using a universal source of wild-type chromosomes as donor, and induced pluripotent stem cells (iPSCs) as acceptor. One of the obstacles to be addressed for translating PSC research into clinical practice is the still unsatisfactory differentiation into transplantable hematopoietic stem or mature cells. We provide an overview of the recent progresses in this field and discuss challenges and potential of iPSC-based therapies for the treatment of inherited blood disorders.

Biological composition analysis of a natural medicine, Faeces Vespertilionis, with complex sources using DNA metabarcoding

Faeces Vespertilionis is a commonly used fecal traditional Chinese medicine. Traditionally, it is identified relying only on morphological characters. This poses a serious challenge to the composition analysis accuracy of this complex biological mixture. Thus, for quality control purposes, an accurate and effective method should be provided for taxonomic identification of Faeces Vespertilionis. In this study, 26 samples of Faeces Vespertilionis from ten provinces in China were tested using DNA metabarcoding. Seven operational taxonomic units (OTUs) were detected as belonging to bats. Among them, Hipposideros armiger (Hodgson, 1835) and Rhinolophus ferrumequinum (Schober and Grimmberger, 1997) were the main host sources of Faeces Vespertilionis samples, with average relative abundances of 59.3% and 24.1%, respectively. Biodiversity analysis showed that Diptera and Lepidoptera were the most frequently consumed insects. At the species level, 19 taxa were clearly identified. Overall, our study used DNA metabarcoding to analyze the biological composition of Faeces Vespertilionis, which provides a new idea for the quality control of this special traditional Chinese medicine.

Induced Pluripotent Stem Cells as a Tool for Modeling Hematologic Disorders and as a Potential Source for Cell-Based Therapies

The breakthrough in human induced pluripotent stem cells (hiPSCs) has revolutionized the field of biomedical and pharmaceutical research and opened up vast opportunities for drug discovery and regenerative medicine, especially when combined with gene-editing technology. Numerous healthy and patient-derived hiPSCs for human disease modeling have been established, enabling mechanistic studies of pathogenesis, platforms for preclinical drug screening, and the development of novel therapeutic targets/approaches. Additionally, hiPSCs hold great promise for cell-based therapy, serving as an attractive cell source for generating stem/progenitor cells or functional differentiated cells for degenerative diseases, due to their unlimited proliferative capacity, pluripotency, and ethical acceptability. In this review, we provide an overview of hiPSCs and their utility in the study of hematologic disorders through hematopoietic differentiation. We highlight recent hereditary and acquired genetic hematologic disease modeling with patient-specific iPSCs, and discuss their applications as instrumental drug screening tools. The clinical applications of hiPSCs in cell-based therapy, including the next-generation cancer immunotherapy, are provided. Lastly, we discuss the current challenges that need to be addressed to fulfill the validity of hiPSC-based disease modeling and future perspectives of hiPSCs in the field of hematology.

Dissecting the complexities of Alzheimer disease with in vitro models of the human brain

Alzheimer disease (AD) is the most prevalent type of dementia. It is marked by severe memory loss and cognitive decline, and currently has limited effective treatment options. Although individuals with AD have common neuropathological hallmarks, emerging data suggest that the disease has a complex polygenic aetiology, and more than 25 genetic loci have been linked to an elevated risk of AD and dementia. Nevertheless, our ability to decipher the cellular and molecular mechanisms that underlie genetic susceptibility to AD, and its progression and severity, remains limited. Here, we discuss ongoing efforts to leverage genomic data from patients using cellular reprogramming technologies to recapitulate complex brain systems and build in vitro discovery platforms. Much attention has already been given to methodologies to derive major brain cell types from pluripotent stem cells. We therefore focus on technologies that combine multiple cell types to recreate anatomical and physiological properties of human brain tissue in vitro. We discuss the advances in the field for modelling four domains that have come into view as key contributors to the pathogenesis of AD: the blood-brain barrier, myelination, neuroinflammation and neuronal circuits. We also highlight opportunities for the field to further interrogate the complex genetic and environmental factors of AD using in vitro models.

Induced pluripotent stem cell-based disease modeling and prospective immune therapy for coronavirus disease 2019

The emergence of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic poses a never before seen challenge to human health and the economy. Considering its clinical impact, with no streamlined therapeutic strategies in sight, it is crucial to understand the infection process of SARS-CoV-2. Our limited knowledge of the mechanisms underlying SARS-CoV-2 infection impedes the development of alternative therapeutics to address the pandemic. This aspect can be addressed by modeling SARS-CoV-2 infection in the human context to facilitate drug screening and discovery. Human induced pluripotent stem cell (iPSC)-derived lung epithelial cells and organoids recapitulating the features and functionality of the alveolar cell types can serve as an in vitro human model and screening platform for SARS-CoV-2. Recent studies suggest an immune system asynchrony leading to compromised function and a decreased proportion of specific immune cell types in coronavirus disease 2019 (COVID-19) patients. Replenishing these specific immune cells may serve as useful treatment modality against SARS-CoV-2 infection. Here the authors review protocols for deriving lung epithelial cells, alveolar organoids and specific immune cell types, such as T lymphocytes and natural killer cells, from iPSCs with the aim to aid investigators in making relevant in vitro models of SARS-CoV-2 along with the possibility derive immune cell types to treat COVID-19.

Specific Blood Cells Derived from Pluripotent Stem Cells: An Emerging Field with Great Potential in Clinical Cell Therapy

Widely known for self-renewal and multilineage differentiation, stem cells can be differentiated into all specialized tissues and cells in the body. In the past few years, a number of researchers have focused on deriving hematopoietic stem cells (HSCs) from pluripotent stem cells (PSCs) as alternative sources for clinic. Existing findings demonstrated that it is feasible to obtain HSCs and certain mature blood lineages from PSCs, except for several issues to be addressed. This short review outlines the technologies used for hematopoietic differentiation in recent years. In addition, the therapeutic value of PSCs as a potential source of various blood cells is also discussed as well as its challenges and directions in future clinical applications.

DL4-μbeads induce T cell lineage differentiation from stem cells in a stromal cell-free system

T cells are pivotal effectors of the immune system and can be harnessed as therapeutics for regenerative medicine and cancer immunotherapy. An unmet challenge in the field is the development of a clinically relevant system that is readily scalable to generate large numbers of T-lineage cells from hematopoietic stem/progenitor cells (HSPCs). Here, we report a stromal cell-free, microbead-based approach that supports the efficient in vitro development of both human progenitor T (proT) cells and T-lineage cells from CD34⁺cells sourced from cord blood, GCSF-mobilized peripheral blood, and pluripotent stem cells (PSCs). DL4-μbeads, along with lymphopoietic cytokines, induce an ordered sequence of differentiation from CD34⁺ cells to CD34⁺CD7⁺CD5⁺ proT cells to CD3⁺αβ T cells. Single-cell RNA sequencing of human PSC-derived proT cells reveals a transcriptional profile similar to the earliest thymocytes found in the embryonic and fetal thymus. Furthermore, the adoptive transfer of CD34⁺CD7⁺ proT cells into immunodeficient mice demonstrates efficient thymic engraftment and functional maturation of peripheral T cells. DL4-μbeads provide a simple and robust platform to both study human T cell development and facilitate the development of engineered T cell therapies from renewable sources.

T cells derived from stem cells can be harnessed for regenerative medicine and cancer immunotherapy, but current technologies limit production and translation. Here, the authors present a serum-free, stromal-cell free DLL4-coated microbead method for the scalable production of T-lineage cells from multiple sources of stem cells.

Cell Fate Reprogramming in the Era of Cancer Immunotherapy

Advances in understanding how cancer cells interact with the immune system allowed the development of immunotherapeutic strategies, harnessing patients' immune system to fight cancer. Dendritic cell-based vaccines are being explored to reactivate anti-tumor adaptive immunity. Immune checkpoint inhibitors and chimeric antigen receptor T-cells (CAR T) were however the main approaches that catapulted the therapeutic success of immunotherapy. Despite their success across a broad range of human cancers, many challenges remain for basic understanding and clinical progress as only a minority of patients benefit from immunotherapy. In addition, cellular immunotherapies face important limitations imposed by the availability and quality of immune cells isolated from donors. Cell fate reprogramming is offering interesting alternatives to meet these challenges. Induced pluripotent stem cell (iPSC) technology not only enables studying immune cell specification but also serves as a platform for the differentiation of a myriad of clinically useful immune cells including T-cells, NK cells, or monocytes at scale. Moreover, the utilization of iPSCs allows introduction of genetic modifications and generation of T/NK cells with enhanced anti-tumor properties. Immune cells, such as macrophages and dendritic cells, can also be generated by direct cellular reprogramming employing lineage-specific master regulators bypassing the pluripotent stage. Thus, the cellular reprogramming toolbox is now providing the means to address the potential of patient-tailored immune cell types for cancer immunotherapy. In parallel, development of viral vectors for gene delivery has opened the door for in vivo reprogramming in regenerative medicine, an elegant strategy circumventing the current limitations of in vitro cell manipulation. An analogous paradigm has been recently developed in cancer immunotherapy by the generation of CAR T-cells in vivo. These new ideas on endogenous reprogramming, cross-fertilized from the fields of regenerative medicine and gene therapy, are opening exciting avenues for direct modulation of immune or tumor cells in situ, widening our strategies to remove cancer immunotherapy roadblocks. Here, we review current strategies for cancer immunotherapy, summarize technologies for generation of immune cells by cell fate reprogramming as well as highlight the future potential of inducing these unique cell identities in vivo, providing new and exciting tools for the fast-paced field of cancer immunotherapy.

Adult-repopulating lymphoid potential of yolk sac blood vessels is not confined to arterial endothelial cells

During embryogenesis, hematopoietic stem progenitor cells (HSPCs) are believed to be derived from hemogenic endothelial cells (HECs). Moreover, arterial feature is proposed to be a prerequisite for HECs to generate HSPCs with lymphoid potential. Although the molecular basis of hematopoietic stem cell-competent HECs has been delicately elucidated within the embryo proper, the functional and molecular characteristics of HECs in the extraembryonic yolk sac (YS) remain largely unresolved. In this study, we initially identified six molecularly different endothelial populations in the midgestational YS through integrated analysis of several single-cell RNA sequencing (scRNA-seq) datasets and validated the arterial vasculature distribution of Gja5⁺ ECs using a Gja5-EGFP reporter mouse model. Further, we explored the hemogenic potential of different EC populations based on their Gja5-EGFP and CD44 expression levels. The hemogenic potential was ubiquitously detected in spatiotemporally different vascular beds on embryonic days (E)8.5-E9.5 and gradually concentrated in CD44-positive ECs from E10.0. Unexpectedly, B-lymphoid potential was detected in the YS ECs as early as E8.5 regardless of their arterial features. Furthermore, the capacity for generating hematopoietic progenitors with in vivo lymphoid potential was found in nonarterial as well as arterial YS ECs on E10.0-E10.5. Importantly, the distinct identities of E10.0-E10.5 HECs between YS and intraembryonic caudal region were revealed by further scRNA-seq analysis. Cumulatively, these findings extend our knowledge regarding the hemogenic potential of ECs from anatomically and molecularly different vascular beds, providing a theoretical basis for better understanding the sources of HSPCs during mammalian development.

Cell and Gene Therapy for Anemia: Hematopoietic Stem Cells and Gene Editing

Hereditary anemia has various manifestations, such as sickle cell disease (SCD), Fanconi anemia, glucose-6-phosphate dehydrogenase deficiency (G6PDD), and thalassemia. The available management strategies for these disorders are still unsatisfactory and do not eliminate the main causes. As genetic aberrations are the main causes of all forms of hereditary anemia, the optimal approach involves repairing the defective gene, possibly through the transplantation of normal hematopoietic stem cells (HSCs) from a normal matching donor or through gene therapy approaches (either in vivo or ex vivo) to correct the patient’s HSCs. To clearly illustrate the importance of cell and gene therapy in hereditary anemia, this paper provides a review of the genetic aberration, epidemiology, clinical features, current management, and cell and gene therapy endeavors related to SCD, thalassemia, Fanconi anemia, and G6PDD. Moreover, we expound the future research direction of HSC derivation from induced pluripotent stem cells (iPSCs), strategies to edit HSCs, gene therapy risk mitigation, and their clinical perspectives. In conclusion, gene-corrected hematopoietic stem cell transplantation has promising outcomes for SCD, Fanconi anemia, and thalassemia, and it may overcome the limitation of the source of allogenic bone marrow transplantation.

Long Non-coding RNA 332443 Inhibits Preadipocyte Differentiation by Targeting Runx1 and p38-MAPK and ERK1/2-MAPK Signaling Pathways

Long non-coding RNAs (lncRNAs) have emerged as integral regulators of pathophysiological processes, but their specific roles and mechanisms in adipose tissue development remain largely unknown. Here, through microarray analysis, co-expression, and tissue specific analysis of adipocyte tissues after fasting for 72 h, we found that Lnc-FR332443 expression was dramatically decreased, as well as the expression of Runx1. The UCSC database and Ensembl database indicated that Lnc-FR332443 is the antisense lncRNA of Runx1. Lnc-FR332443 and Runx1 are highly enriched in adipose tissue and downregulated during adipogenic differentiation. Adipose tissue-specific knockdown of Lnc-FR332443 increased fat mass in vivo, and specific knockdown of Lnc-FR332443 in 3T3-L1 preadipocytes promoted adipogenic differentiation. In this process, Runx1 expression was decreased when Lnc-FR332443 was downregulated in adipocytes or 3T3-L1 preadipocytes, and vice versa, when Lnc-FR332443 was upregulated, the expression of Runx1 was increased. However, overexpression of Runx1 decreased the expression of the adipocyte cell marker genes PPARγ, C/EBPα and FABP4 significantly, while not affected the expression of Lnc-FR332443. Mechanistically, Lnc-FR332443 positively regulates Runx1 expression in mouse adipocytes and suppresses adipocyte differentiation by attenuating the phosphorylation of MAPK-p38 and MAPK-ERK1/2 expression. Thus, this study indicated that Lnc-FR332443 inhibits adipogenesis and which might be a drug target for the prevention and treatment of obesity.

Leaving no one behind: tracing every human thymocyte by single-cell RNA-sequencing

The thymus is the primary organ for T-cell development, providing an essential microenvironment consisting of the appropriate cytokine milieu and specialized stromal cells. Thymus-seeding progenitors from circulation immigrate into the thymus and undergo the stepwise T-cell specification, commitment, and selection processes. The transcriptional factors, epigenetic regulators, and signaling pathways involved in the T-cell development have been intensively studied using mouse models. Despite our growing knowledge of T-cell development, major questions remain unanswered regarding the ontogeny and early events of T-cell development at the fetal stage, especially in humans. The recently developed single-cell RNA-sequencing technique provides an ideal tool to investigate the heterogeneity of T-cell precursors and the molecular mechanisms underlying the divergent fates of certain T-cell precursors at the single-cell level. In this review, we aim to summarize the current progress of the study on human thymus organogenesis and thymocyte and thymic epithelial cell development, which is to shed new lights on developing novel strategies for in vitro T-cell regeneration and thymus rejuvenation.

Hematopoietic stem cells from pluripotent stem cells: Clinical potential, challenges, and future perspectives

The generation of hematopoietic stem cells (HSCs) from induced pluripotent stem cells (iPSCs) is an active and promising area of research; however, generating engraftable HSCs remains a major obstacle. Ex vivo HSC derivation from renewable sources such as iPSCs offers an experimental tool for studying developmental hematopoiesis, disease modeling, and drug discovery, and yields tremendous therapeutic potential for malignant and nonmalignant hematological disorders. Although initial attempts mostly recapitulated yolk sac primitive/definitive hematopoiesis with inability to engraft, recent advances suggest the feasibility of engraftable HSC derivation from iPSCs utilizing ectopic transcription factor expression. Strategic development for de novo HSC generation includes further investigations of HSC ontogeny, and elucidation of critical signaling pathways, epigenetic modulations, HSC and iPSC microenvironment, and cell-cell interactions that contribute to stem cell biology and function.

Hematopoietic lineage-converted T cells carrying tumor-associated antigen-recognizing TCRs effectively kill tumor cells

Tumor-associated antigen (TAA) T-cell receptor (TCR) gene-engineered T cells exhibit great potential in antitumor immunotherapy. Considering the high costs and low availability of patient-derived peripheral blood T cells, substantial efforts have been made to explore alternatives to natural T cells. We previously reported that enforced expression of Hoxb5 converted B cells into induced T (iT) cells in vivo Here, we successfully regenerated naive OT1 (major histocompatibility complex I restricted ovalbumin antigen) iT cells (OT1-iT) in vivo by expressing Hoxb5 in pro-pre-B cells in the OT1 transgenic mouse. The OT1-iT cells can be activated and expanded in vitro in the presence of tumor cells. Particularly, these regenerated OT1-iT cells effectively eradicated tumor cells expressing the TAA (ovalbumin) both in vitro and in vivo This study provides insights into the translational applications of blood lineage-transdifferentiated T cells in immunotherapy.

Two-step protocol for regeneration of immunocompetent T cells from mouse pluripotent stem cells

Numerous efforts have been attempted to regenerate T cells in culture dish from pluripotent stem cells (PSCs). However, in vitro generated T cells exhibited extremely low activity and compromised immunocompetency in vivo. Here, we describe a two-step protocol for regenerating functional T cells using an inducible Runx1-Hoxa9-PSC (iR9-PSCs) line. The procedure mainly includes generation of induced hematopoietic progenitor cells (iHPCs) in vitro, transplantation, and development of functional induced T cells (iT) in vivo via transplantation. The entire induction process in vitro requires 21 days before iHPCs transplantation. The development of mature T cells in vivo takes 4 to 6 weeks post-transplantation. We provide a simple and reproducible approach for functional T cell regeneration from iR9-PSCs for research purpose.