A sticky wicket: Defining molecular functions for CD34 in hematopoietic cells

Modeling human natural killer cell development and drug response in a microfluidic bone marrow model

Introduction

The human bone marrow is a complex organ that is critical for self-renewal and differentiation of hematopoietic progenitor cells into various lineages of blood cells. Perturbations of the hematopoietic system have been reported to cause numerous diseases. Yet, understanding the fundamental biology of the human bone marrow in health and disease and during the preclinical stages of drug development is challenging due to the complexity of studying or manipulating the human bone marrow. Human cell-based microfluidic bone marrow models are promising research tools to explore multi-lineage differentiation of human stem and progenitor cells over long periods of time.

Methods

Human hematopoietic stem and progenitor cells were cultured with mesenchymal stromal cells on a zirconium oxide ceramic scaffold in a microfluidic device recapitulating the human bone marrow. NK cell differentiation was induced by the application of a lymphoid cultivation medium containing IL-15. The kinetics of differentiation into mature NK cells was traced by flow cytometry over a period of up to seven weeks, and functionality was measured by stimulation with phorbol myristate acetate (PMA) and ionomycin. The effect of an anti-IL-15 monoclonal antibody (TEV-53408) on different NK cell subtypes was tested at different time points.

Results

Our data shows that within 28 days of culture, differentiation into all developmental stages of NK cells was accomplished in this system. Alongside with the NK cells, myeloid cells developed in the system including granulocytes, monocytes and dendritic cells. The differentiated NK cells could be activated after stimulation with PMA and ionomycin indicating the functionality of the cells. Treatment with an anti-IL-15 antibody induced a reduction in proliferation of late-stage NK cells as shown by EdU staining. This led to significantly dose dependent reduction in the number of circulating stage 4 - 6 NK cells in the system after one week of treatment. This effect was partially reversible after a two-week treatment-free period.

Discussion

In summary, the presented model enables investigation of human NK cell development in the bone marrow and provides a basis to study related diseases and drug response effects in a microenvironment that is designed mimic human physiology.

CD34 distribution in C-fiber low threshold mechanoreceptors in the mouse dorsal root ganglion and spinal cord

CD34 is a well-known cell marker of hematopoietic stem/ progenitor cells, endothelial cells, and fibrocytes. In the peripheral nervous system, a certain type of primary sensory neuron C-fiber low threshold mechanoreceptors (C-LTMRs) are reported to express CD34 mRNA. Here, we investigated the distribution of CD34 protein among putative C-LTMRs (pC-LTMR) using pC-LTMR markers such as VGLUT3 and TH in the dorsal root ganglion (DRG) and spinal cord. CD34 was frequently observed in DRG neurons double-positive for VGLUT3 and TH and single-positive for VGLUT3 in C8 and L4 levels, however, in C4 and L1 levels most of CD34-positive DRG neurons were demonstrated to be double-positive for VGLUT3 and TH. As for the termination, CD34-positive DRG neurons terminated in the ventral part of inner lamina II (lamina IIiv). At C4 and L1 levels of the dorsal horn, CD34 was observed in the entire region of lamina IIiv, however, in C8 and L4 levels of the dorsal horn CD34 was not detected in the medial part of lamina IIiv, which receives neural inputs from DRG neurons that innervate palm or sole skin. These results indicate that CD34 is expressed in pC-LTMRs and suggest that CD34 may play a role in providing C-LTMRs with a specific sensation by maintaining neural circuits.

ISG15-LFA1 interactions in latent HIV clearance: mechanistic implications in designing antiviral therapies

Interferon types-I/II (IFN-αβ/γ) secretions are well-established antiviral host defenses. The human immunodeficiency virus (HIV) particles are known to prevail following targeted cellular interferon secretion. CD4+ T-lymphocytes are the primary receptor targets for HIV entry, but the virus has been observed to hide (be latent) successfully in these cells through an alternate entry route via interactions with LFA1. HIV facilitates its post-entry latency-driven mode of hiding through these interactions to displace or inhibit ISG15 by forming the HIV1-LFA1 complex in lieu of ISG15-LFA1, which would at least transiently halt and bypass type-I IFN secretion. This could explain why the elimination of HIV from cellular hideouts is difficult. Hence, HIV clearance needs to be addressed to reverse its latency in LFA1+ T-lymphocytes and CD34+/CD133+ early progenitor stem cells. In the context of hematopoietic or endothelial stem-progenitor cells (HSPC/ESPC), we discuss the potential role of LFA1 in HIV permissiveness and latency in LFA1-CD34+/CD133+ versus LFA1+CD34+/CD133+ HSPCs/ESPCs. In HIV latency, the viral particles may remain engaged on the naïve-resting cells' LFA1, which are then unable to accommodate the ISG15 molecules owing to conformational changes induced upon occupation by the virus at the ISG15-LFA1 binding or interaction sites through halting of the subsequent downstream type-II IFN secretion. Viral binding to LFA1, including its transfer through activated-naïve cell-cell contacts may be a key step that needs to be addressed to prevent "transient or partial" virus-induced shutdown of type-I IFN secretion. This process allows an alternate viral entry and hideout site via LFA1. The subsequent administration of recombinant ISG15 may ensure sufficient type I/II IFN release to promote, enhance, or sustain the innate immune responses. Thus, combination antiviral therapies could potentially include exogenous ISG15 to maintain or sustain biologically and clinically relevant ISG15-LFA1 interactions. In addition to alternating with co-challenges of PKC-pro-LRA-drug modulators, this is administered post (antiretroviral therapy) and continued with periodic ART until permanent elimination of viral resurgence and latency is achieved in patients with HIV/AIDS. This triple-combination drug regimen is expected to pave the path for systemic virus clearance in vivo.

Single-cell transcriptome analysis reveals CD34 as a marker of human sinoatrial node pacemaker cardiomyocytes

The sinoatrial node regulates the heart rate throughout life. Failure of this primary pacemaker results in life-threatening, slow heart rhythm. Despite its critical function, the cellular and molecular composition of the human sinoatrial node is not resolved. Particularly, no cell surface marker to identify and isolate sinoatrial node pacemaker cells has been reported. Here we use single-nuclei/cell RNA sequencing of fetal and human pluripotent stem cell-derived sinoatrial node cells to reveal that they consist of three subtypes of pacemaker cells: Core Pacemaker, Sinus Venosus, and Transitional Cells. Our study identifies a host of sinoatrial node pacemaker markers including MYH11, BMP4, and the cell surface antigen CD34. We demonstrate that sorting for CD34+ cells from stem cell differentiation cultures enriches for sinoatrial node cells exhibiting a functional pacemaker phenotype. This sinoatrial node pacemaker cell surface marker is highly valuable for stem cell-based disease modeling, drug discovery, cell replacement therapies, and the targeted delivery of therapeutics to sinoatrial node cells in vivo using antibody-drug conjugates.

CD34 as a potential prognostic indicator for camrelizumab response in advanced non-small-cell lung cancer: insights from digital spatial profiling

Background

Given that only a small subset of patients with advanced non-small-cell lung cancer (aNSCLC) benefit from immune checkpoint inhibitors (ICIs), the effectiveness of ICIs is often compromised by the complex interplay within the tumor microenvironment (TME).

Objectives

To identify predictive biomarkers associated with ICI resistance at a multi-omics spatial level.

Design

A total of eight aNSCLC patients who received first-line anti-programmed cell death protein-1 (PD-1) monoclonal antibody camrelizumab at Shandong Cancer Hospital and Institute between 2021 and 2022 were included in the discovery cohort. An additional validation cohort of 45 samples from camrelizumab-treated aNSCLC patients was also enrolled.

Methods

NanoString GeoMx® digital spatial profiling was conducted at the transcriptomic and proteomic level within pan-cytokeratin (panCK+), CD45+, and CD68+ compartments. For validation, multiplex immunofluorescence (mIF) staining was performed.

Results

Distinct spatial expression patterns and levels of immune infiltration were observed between tumor and leukocyte compartments. Higher CD34 expression in the macrophage compartment correlated with poorer prognosis and response to camrelizumab (p < 0.05). mIF validation confirmed the association of elevated CD34 expression level with reduced progression-free survival (PFS; hazard ratio (HR) = 5.011, 95% confidence interval: 1.057-23.752, p = 0.042), outperforming traditional tumor markers in predictive accuracy.

Conclusion

Our findings identify CD34 as a novel spatial biomarker for anti-PD-1 therapy efficacy, potentially guiding the selection of aNSCLC patients who are more likely to benefit from ICI treatment.

Trial registration

ChiCTR2000040416.

Non-endothelial expression of endomucin in the mouse and human choroid

Endomucin (EMCN) is a 261 amino acid transmembrane glycoprotein that is highly expressed by venous and capillary endothelial cells where it plays a role in VEGF-mediated angiogenesis and regulation of immune cell recruitment. However, it is better known as a histological marker, where it has become widespread due to the commercial availability of high-quality antibodies that work under a wide range of conditions and in many tissues. The specificity of EMCN staining has been well-validated in retinal vessels, but while it has been used extensively as a marker in other tissues of the eye, including the choroid, the pattern of expression has not been described in detail. Here, in addition to endothelial expression in the choriocapillaris and deeper vascular layers, we characterize a population of EMCN-positive perivascular cells in the mouse choroid that did not co-localize with cells expressing other endothelial markers such as PECAM1 or PODXL. To confirm that these cells represented a new population of EMCN-expressing stromal cells, we then performed single cell RNA sequencing in choroids from adult wild-type mice. Analysis of this new dataset confirmed that, in addition to endothelial cells, Emcn mRNA expression was present in choroidal pericytes and a subset of fibroblasts, but not vascular smooth muscle cells. Besides Emcn, no known endothelial gene expression was detected in these cell populations, confirming that they did not represent endothelial-stromal doublets, a common technical artifact in single cell RNA seq datasets. Instead, choroidal Emcn-expressing fibroblasts exhibited high levels of chemokine and interferon signaling genes, while Emcn-negative fibroblasts were enriched in genes encoding extracellular matrix proteins. Emcn expressing fibroblasts were also detected in published datasets from mouse brain and human choroid, suggesting that stromal Emcn expression was not unique to the choroid and was evolutionarily conserved. Together, these findings highlight unique fibroblast and pericyte populations in the choroid and provide new context for the role of EMCN in the eye.

Against all odds: The road to success in the development of human immune reconstitution mice

The mouse genome has a high degree of homology with the human genome, and its physiological, biochemical, and developmental regulation mechanisms are similar to those of humans; therefore, mice are widely used as experimental animals. However, it is undeniable that interspecies differences between humans and mice can lead to experimental errors. The differences in the immune system have become an important factor limiting current immunological research. The application of immunodeficient mice provides a possible solution to these problems. By transplanting human immune cells or tissues, such as peripheral blood mononuclear cells or hematopoietic stem cells, into immunodeficient mice, a human immune system can be reconstituted in the mouse body, and the engrafted immune cells can elicit human-specific immune responses. Researchers have been actively exploring the development and differentiation conditions of host recipient animals and grafts in order to achieve better immune reconstitution. Through genetic engineering methods, immunodeficient mice can be further modified to provide a favorable developmental and differentiation microenvironment for the grafts. From initially only being able to reconstruct single T lymphocyte lineages, it is now possible to reconstruct lymphoid and myeloid cells, providing important research tools for immunology-related studies. In this review, we compare the differences in immune systems of humans and mice, describe the development history of human immune reconstitution from the perspectives of immunodeficient mice and grafts, and discuss the latest advances in enhancing the efficiency of human immune cell reconstitution, aiming to provide important references for immunological related researches.

Umbilical cord blood derived cell expansion: a potential neuroprotective therapy

Umbilical cord blood (UCB) is a rich source of beneficial stem and progenitor cells with known angiogenic, neuroregenerative and immune-modulatory properties. Preclinical studies have highlighted the benefit of UCB for a broad range of conditions including haematological conditions, metabolic disorders and neurological conditions, however clinical translation of UCB therapies is lacking. One barrier for clinical translation is inadequate cell numbers in some samples meaning that often a therapeutic dose cannot be achieved. This is particularly important when treating adults or when administering repeat doses of cells. To overcome this, UCB cell expansion is being explored to increase cell numbers. The current focus of UCB cell expansion is CD34+ haematopoietic stem cells (HSCs) for which the main application is treatment of haematological conditions. Currently there are 36 registered clinical trials that are examining the efficacy of expanded UCB cells with 31 of these being for haematological malignancies. Early data from these trials suggest that expanded UCB cells are a safe and feasible treatment option and show greater engraftment potential than unexpanded UCB. Outside of the haematology research space, expanded UCB has been trialled as a therapy in only two preclinical studies, one for spinal cord injury and one for hind limb ischemia. Proteomic analysis of expanded UCB cells in these studies showed that the cells were neuroprotective, anti-inflammatory and angiogenic. These findings are also supported by in vitro studies where expanded UCB CD34+ cells showed increased gene expression of neurotrophic and angiogenic factors compared to unexpanded CD34+ cells. Preclinical evidence demonstrates that unexpanded CD34+ cells are a promising therapy for neurological conditions where they have been shown to improve multiple indices of injury in rodent models of stroke, Parkinson's disease and neonatal hypoxic ischemic brain injury. This review will highlight the current application of expanded UCB derived HSCs in transplant medicine, and also explore the potential use of expanded HSCs as a therapy for neurological conditions. It is proposed that expanded UCB derived CD34+ cells are an appropriate cellular therapy for a range of neurological conditions in children and adults.

Endomucin marks quiescent long-term multi-lineage repopulating hematopoietic stem cells and is essential for their transendothelial migration

Endomucin (EMCN) currently represents the only hematopoietic stem cell (HSC) marker expressed by both murine and human HSCs. Here, we report that EMCN+ long-term repopulating HSCs (LT-HSCs; CD150+CD48-LSK) have a higher long-term multi-lineage repopulating capacity compared to EMCN- LT-HSCs. Cell cycle analyses and transcriptional profiling demonstrated that EMCN+ LT-HSCs were more quiescent compared to EMCN- LT-HSCs. Emcn-/- and Emcn+/+ mice displayed comparable steady-state hematopoiesis, as well as frequencies, transcriptional programs, and long-term multi-lineage repopulating capacity of their LT-HSCs. Complementary functional analyses further revealed increased cell cycle entry upon treatment with 5-fluorouracil and reduced granulocyte colony-stimulating factor (GCSF) mobilization of Emcn-/- LT-HSCs, demonstrating that EMCN expression by LT-HSCs associates with quiescence in response to hematopoietic stress and is indispensable for effective LT-HSC mobilization. Transplantation of wild-type bone marrow cells into Emcn-/- or Emcn+/+ recipients demonstrated that EMCN is essential for endothelial cell-dependent maintenance/self-renewal of the LT-HSC pool and sustained blood cell production post-transplant.

Non-endothelial expression of Endomucin in the mouse and human choroid

Endomucin (EMCN) is a 261 AA transmembrane glycoprotein that is highly expressed by venous and capillary endothelial cells where it plays a role in VEGF-mediated angiogenesis and regulation of immune cell recruitment. However, it is better known as a histological marker, where it has become widespread due to the commercial availability of high-quality antibodies that work under a wide range of conditions and in many tissues. The specificity of EMCN staining has been well-validated in retinal vessels, but while it has been used extensively as a marker in other tissues of the eye, including the choroid, the pattern of expression has not been described in detail. Here, in addition to endothelial expression in the choriocapillaris and deeper vascular layers, we characterize a population of EMCN-positive perivascular cells in the mouse choroid that did not co-localize with cells expressing other endothelial markers such as PECAM1 or PODXL. To confirm that these cells represented a new population of EMCN-expressing stromal cells, we then performed single cell RNA sequencing in choroids from adult wild-type mice. Analysis of this new dataset confirmed that, in addition to endothelial cells, Emcn mRNA expression was present in choroidal pericytes and a subset of fibroblasts, but not vascular smooth muscle cells. Besides Emcn , no known endothelial gene expression was detected in these cell populations, confirming that they did not represent endothelial-stromal doublets, a common technical artifact in single cell RNA seq datasets. Instead, choroidal Emcn -expressing fibroblasts exhibited high levels of chemokine and interferon signaling genes, while Emcn -negative fibroblasts were enriched in genes encoding extracellular matrix proteins. Emcn expressing fibroblasts were also detected in published datasets from mouse brain and human choroid, suggesting that stromal Emcn expression was not unique to the choroid and was evolutionarily conserved. Together, these findings highlight unique fibroblast and pericyte populations in the choroid and provide new context for the role of EMCN in angiogenesis and immune cell recruitment.

HSP90 Inhibitor PU-H71 in Combination with BH3-Mimetics in the Treatment of Acute Myeloid Leukemia

Targeting the molecular chaperone HSP90 and the anti-apoptotic proteins MCL1 and BCL2 may be a promising novel approach in the treatment of acute myeloid leukemia (AML). The HSP90 inhibitor PU-H71, MCL1 inhibitor S63845, and BCL2 inhibitor venetoclax were assessed as single agents and in combination for their ability to induce apoptosis and cell death in leukemic cells. AML cells represented all major morphologic and molecular subtypes including FLT3-ITD and TP53 mutant AML cell lines and a variety of patient-derived AML cells. Results: PU-H71 and combination treatments with MCL1 inhibitor S63845 or BCL2 inhibitor venetoclax induced cell cycle arrest and apoptosis in susceptible AML cell lines and primary AML. The majority of the primary AML samples were responsive to PU-H71 in combination with BH3 mimetics. Elevated susceptibility to PU-H71 and S63845 was associated with FLT3 mutated AML with CD34 < 20%. Elevated susceptibility to PU-H71 and venetoclax was associated with primary AML with CD117 > 80% and CD11b < 45%. The combination of HSP90 inhibitor PU-H71 and MCL1 inhibitor S63845 may be a candidate treatment for FLT3-mutated AML with moderate CD34 positivity while the combination of HSP90 inhibitor PU-H71 and BCL2 inhibitor venetoclax may be more effective in the treatment of primitive AML with high CD117 and low CD11b positivity.

Role of CD34 in inflammatory bowel disease

Inflammatory bowel disease (IBD) is caused by a variety of pathogenic factors, including chronic recurrent inflammation of the ileum, rectum, and colon. Immune cells and adhesion molecules play an important role in the course of the disease, which is actually an autoimmune disease. During IBD, CD34 is involved in mediating the migration of a variety of immune cells (neutrophils, eosinophils, and mast cells) to the inflammatory site, and its interaction with various adhesion molecules is involved in the occurrence and development of IBD. Although the function of CD34 as a partial cell marker is well known, little is known on its role in IBD. Therefore, this article describes the structure and biological function of CD34, as well as on its potential mechanism in the development of IBD.

Low input capture Hi-C (liCHi-C) identifies promoter-enhancer interactions at high-resolution

Long-range interactions between regulatory elements and promoters are key in gene transcriptional control; however, their study requires large amounts of starting material, which is not compatible with clinical scenarios nor the study of rare cell populations. Here we introduce low input capture Hi-C (liCHi-C) as a cost-effective, flexible method to map and robustly compare promoter interactomes at high resolution. As proof of its broad applicability, we implement liCHi-C to study normal and malignant human hematopoietic hierarchy in clinical samples. We demonstrate that the dynamic promoter architecture identifies developmental trajectories and orchestrates transcriptional transitions during cell-state commitment. Moreover, liCHi-C enables the identification of disease-relevant cell types, genes and pathways potentially deregulated by non-coding alterations at distal regulatory elements. Finally, we show that liCHi-C can be harnessed to uncover genome-wide structural variants, resolve their breakpoints and infer their pathogenic effects. Collectively, our optimized liCHi-C method expands the study of 3D chromatin organization to unique, low-abundance cell populations, and offers an opportunity to uncover factors and regulatory networks involved in disease pathogenesis.

Comprehensive Transcriptional Profiling and Mouse Phenotyping Reveals Dispensable Role for Adipose Tissue Selective Long Noncoding RNA Gm15551

Cold and nutrient-activated brown adipose tissue (BAT) is capable of increasing systemic energy expenditure via the uncoupled respiration and secretion of endocrine factors, thereby protecting mice against diet-induced obesity and improving insulin response and glucose tolerance in men. Long non-coding RNAs (lncRNAs) have recently been identified as fine-tuning regulators of cellular function. While certain lncRNAs have been functionally characterised in adipose tissue, their overall contribution in the activation of BAT remains elusive. We identified lncRNAs correlating to interscapular brown adipose tissue (iBAT) function in a high fat diet (HFD) and cold stressed mice. We focused on Gm15551, which has an adipose tissue specific expression profile, is highly upregulated during adipogenesis, and downregulated by β-adrenergic activation in mature adipocytes. Although we performed comprehensive transcriptional and adipocyte physiology profiling in vitro and in vivo, we could not detect an effect of gain or loss of function of Gm15551.

Senescence State in Mesenchymal Stem Cells at Low Passages: Implications in Clinical Use

Mesenchymal stem cells (MSCs) are multipotent cells found in various tissues and are easily cultivated. For use in clinical protocols, MSCs must be expanded to obtain an adequate number of cells, but a senescence state may be instituted after some passages, reducing their replicative potential. In this study, we report a case where MSC derived from an elderly donor acquired a senescence state after three passages. The bone marrow was aspirated from a female patient submitted to a cell therapy for the incontinency urinary protocol; MSCs were cultivated with DMEM low glucose, supplemented with 10% autologous serum (AS) plus 1% L-glutamine and 1% antibiotic/antimycotic. Senescence analysis was performed by β-galactosidase staining after 24 and 48 h. Controls were established using BM-MSC from healthy donors and used for senescence and gene expression assays. Gene expression was performed using RT-PCR for pluripotency genes, such as SOX2, POU5F1, NANOG, and KLF4. MSC telomere length was measured by the Southern blotting technique, and MSCs were also analyzed for their capacity to differentiate into adipocytes, chondrocytes, and osteocytes. The patient’s MSC expansion using AS displayed an early senescence state. In order to understand the role of AS in senescence, MSCs were then submitted to two different culture conditions: 1) with AS or 2) with FBS supplementation. Senescence state was assessed after 24 h, and no statistical differences were observed between the two conditions. However, patients’ cells cultured with AS displayed a higher number of senescence cells than FBS medium after 48 h (p = 0.0018). Gene expression was performed in both conditions; increased expression of KLF4 was observed in the patient’s cells in comparison to healthy controls (p = 0.0016); reduced gene expression was observed for NANOG (p = 0.0016) and SOX2 (p = 0.0014) genes. Telomere length of the patient’s cells was shorter than that of a healthy donor and that of a patient of similar age. Osteocyte differentiation seemed to be more diffuse than that of the healthy donor and that of the patient of similar age. MSCs could enter a senescence state during expansion in early passages and can impact MSC quality for clinical applications, reducing their efficacy when administered.

The miR151 and miR5100 Transfected Bone Marrow Stromal Cells Increase Myoblast Fusion in IGFBP2 Dependent Manner

Background

Bone marrow stromal cells (BMSCs) form a perivascular cell population in the bone marrow. These cells do not present naïve myogenic potential. However, their myogenic identity could be induced experimentally in vitro or in vivo. In vivo, after transplantation into injured muscle, BMSCs rarely fused with myofibers. However, BMSC participation in myofiber reconstruction increased if they were modified by NICD or PAX3 overexpression. Nevertheless, BMSCs paracrine function could play a positive role in skeletal muscle regeneration. Previously, we showed that SDF-1 treatment and coculture with myofibers increased BMSC ability to reconstruct myofibers. We also noticed that SDF-1 treatment changed selected miRNAs expression, including miR151 and miR5100.

Methods

Mouse BMSCs were transfected with miR151 and miR5100 mimics and their proliferation, myogenic differentiation, and fusion with myoblasts were analyzed.

Results

We showed that miR151 and miR5100 played an important role in the regulation of BMSC proliferation and migration. Moreover, the presence of miR151 and miR5100 transfected BMSCs in co-cultures with human myoblasts increased their fusion. This effect was achieved in an IGFBP2 dependent manner.

Conclusions

Mouse BMSCs did not present naïve myogenic potential but secreted proteins could impact myogenic cell differentiation. miR151 and miR5100 transfection changed BMSC migration and IGFBP2 and MMP12 expression in BMSCs. miR151 and miR5100 transfected BMSCs increased myoblast fusion in vitro.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12015-022-10350-y.

A minimal standardized human bone marrow microphysiological system to assess resident cell behavior during normal and pathological processes

Bone marrow is a complex and dynamic microenvironment that provides essential cues to resident cells. We developed a standardized three-dimensional (3D) model to decipher mechanisms that control human cells during hematological and non-hematological processes. Our simple 3D-model is constituted of a biphasic calcium phosphate-based scaffold and human cell lines to ensure a high reproducibility. We obtained a minimal well-organized bone marrow-like structure in which various cell types and secreted extracellular matrix can be observed and characterized by in situ imaging or following viable cell retrieval. The complexity of the system can be increased and customized, with each cellular component being independently modulated according to the issue investigated. Introduction of pathological elements in this 3D-system accurately reproduced changes observed in patient bone marrow. Hence, we have developed a handy and flexible standardized microphysiological system that mimics human bone marrow, allowing histological analysis and functional assays on collected cells.

ASCs and their role in obesity and metabolic diseases

We describe adipose stromal/stem cells (ASCs) in the structural/functional context of the adipose tissue (AT) stem niche (adiponiche), including cell-cell interactions and the microenvironment, and emphasize findings obtained in humans and in lineage-tracing models. ASCs have distinctive markers, 'colors', and anatomical 'locations' which influence their functions. Each adiponiche component can become impaired, thereby contributing to the pathological AT alterations seen in obesity and metabolic diseases. We discuss adiposopathy with a focus on adiponiche dysfunction, and underline the mechanisms that control AT expansion and energy balance. Better understanding of adiponiche regulation and ASC features could help to identify therapeutic targets that favor weight loss and counteract weight regain, and also contribute to innovative strategies for regenerative medicine.

Asymmetric organelle inheritance predicts human blood stem cell fate

Understanding human hematopoietic stem cell fate control is important for their improved therapeutic manipulation. Asymmetric cell division, the asymmetric inheritance of factors during division instructing future daughter cell fates, was recently described in mouse blood stem cells. In human blood stem cells, the possible existence of asymmetric cell division remained unclear due to technical challenges in its direct observation. Here, we use long-term quantitative single-cell imaging to show that lysosomes and active mitochondria are asymmetrically inherited in human blood stem cells and that their inheritance is a coordinated, non-random process. Furthermore, multiple additional organelles, including autophagosomes, mitophagosomes, autolysosomes and recycling endosomes show preferential asymmetric co-segregation with lysosomes. Importantly, asymmetric lysosomal inheritance predicts future asymmetric daughter cell cycle length, differentiation and stem cell marker expression, while asymmetric inheritance of active mitochondria correlates with daughter metabolic activity. Hence, human hematopoietic stem cell fates are regulated by asymmetric cell division, with both mechanistic evolutionary conservation and differences to the mouse system.

Toxocara canis Infection Alters lncRNA and mRNA Expression Profiles of Dog Bone Marrow

Bone marrow is the main hematopoietic organ that produces red blood cells, granulocytes, monocyte/macrophages, megakaryocytes, lymphocytes, and myeloid dendritic cells. Many of these cells play roles in the pathogenesis of Toxocara canis infection, and understanding how infection alters the dynamics of transcription regulation in bone marrow is therefore critical for deciphering the global changes in the dog transcriptional signatures during T. canis infection. In this study, long non-coding RNA (lncRNA) and messenger RNA (mRNA) expression profiles in the bone marrow of Beagle dogs infected with T. canis were determined at 12 h post-infection (hpi), 24 hpi, 96 hpi, and 36 days post-infection (dpi). RNA-sequencing and bioinformatics analysis identified 1,098, 984, 1,120, and 1,305 differentially expressed lncRNAs (DElncRNAs), and 196, 253, 223, and 328 differentially expressed mRNAs (DEmRNAs) at 12 h, 24 h, 96 h, and 36 days after infection, respectively. We also identified 29, 36, 38, and 68 DEmRNAs potentially cis-regulated by 44, 44, 51, and 80 DElncRNAs at 12 hpi, 24 hpi, 96 hpi, and 36 dpi, respectively. To validate the sequencing findings, qRT-PCR was performed on 10 randomly selected transcripts. Many altered genes were involved in the differentiation of bone marrow cells. GO of DElncRNAs and GO and KEGG pathway analyses of DEmRNAs revealed alterations in several signaling pathways, including pathways involved in energy metabolism, amino acid biosynthesis and metabolism, Wnt signaling pathway, Huntington's disease, HIF-1 signaling pathway, cGMP–PKG signaling pathway, dilated cardiomyopathy, and adrenergic signaling in cardiomyocytes. These findings revealed that bone marrow of T. canis-infected dogs exhibits distinct lncRNA and mRNA expression patterns compared to healthy control dogs. Our data provide novel insights into T. canis interaction with the definitive host and shed light on the significance of the non-coding portion of the dog genome in the pathogenesis of toxocariasis.

Macrophage and Lymphocyte Infiltration Is Associated with Volumetric Tumor Size but Not with Volumetric Growth in the Tübingen Schwannoma Cohort

Most patients with vestibular schwannomas can be cured with microsurgical resection, or tumor growth can be stabilized by radiotherapy in certain cases. Recurrence is rare but usually difficult to treat. Treatment alternatives to local therapies are not established. There is growing evidence of the role of inflammatory processes in schwannomas, which may be exploitable by targeted innovative therapies. To further define the impact of inflammation with tumor growth in vestibular schwannoma, we performed immunohistochemical analyses of CD3, CD8, CD68 and CD163 to assess lymphocyte and macrophage infiltration in 923 tumor tissue samples of surgically resected vestibular schwannomas. An inflammatory score was compared with tumor size and volumetric growth. We observed a significantly larger preoperative tumor size with increased expression rates of CD3, CD8, CD68 and CD163 (p < 0.0001, p < 0.0001, p = 0.0015 and p < 0.0001, respectively), but no differences in percentual volumetric tumor growth. When all four markers were combined as an inflammatory score, tumors with high inflammatory infiltration showed slower percentual growth in a multivariate analysis, including MIB1 expression (p = 0.0249). We conclude that inflammatory cell infiltration increases with larger tumor size but is associated with slower percentual volumetric tumor growth.

Safety and efficacy of autologous non-hematopoietic enriched stem cell nebulization in COVID-19 patients: a randomized clinical trial, Abu Dhabi 2020

BACKGROUND

The novel SARS-CoV-2 has caused the coronavirus disease 2019 (COVID-19) pandemic. Currently, with insufficient worldwide vaccination rates, identifying treatment solutions to reduce the impact of the virus is urgently needed.

METHOD

An adaptive, multicentric, open-label, and randomized controlled phase I/II clinical trial entitled the "SENTAD-COVID Study" was conducted by the Abu Dhabi Stem Cells Center under exceptional conditional approval by the Emirates Institutional Review Board (IRB) for COVID-19 Research Committee from April 4th to July 31st, 2020, using an autologous peripheral blood non-hematopoietic enriched stem cell cocktail (PB-NHESC-C) administered by compressor (jet) nebulization as a complement to standard care therapy. The primary endpoints include safety and efficacy assessments, adverse events, the mortality rate within 28 days, and the time to clinical improvement as measured by a 2-point reduction on a seven-category ordinal scale or discharge from the hospital whichever occurred first.

RESULTS

The study included a total of 139 randomized COVID-19 patients, with 69 in the experimental group and 70 in the control group (standard care). Overall survival was 94.20% for the cocktail-treated group vs. 90.27% for the control group. Adverse events were reported in 50 (72.46%) patients receiving PB-NHESC-C and 51 (72.85%) in the control group (p = 0.9590), with signs and symptoms commonly found in COVID-19. After the first 9 days of the intervention, 67.3% of cocktail-treated patients recovered and were released from hospitals compared to 53.1% (RR = 0.84; 95% CI, 0.56-1.28) in the control group. Improvement, i.e., at least a 2-point reduction in the severity scale, was more frequently observed in cocktail-treated patients (42.0%) than in controls (17.0%) (RR = 0.69; 95% CI, 0.56-0.88).

CONCLUSIONS

Cocktail treatment improved clinical outcomes without increasing adverse events. Thus, the nebulization of PB-NHESC-C was safe and effective for treatment in most of these patients.

TRIAL REGISTRATION

ClinicalTrials.gov. NCT04473170. It was retrospectively registered on July 16th, 2020.