Validity evidence for a team-leading assessment tool in pediatric emergency resuscitations using video review.

Background: Effective leadership of health care action teams has demonstrated positive influence on team performance and patient care, but there is no consensus on how to assess these skills. We developed a novel team leadership assessment tool for leaders of interprofessional pediatric resuscitation teams and collected validity evidence for this tool using video review. Methods: This was a prospective cohort study from November 2021 to October 2022. A novel team leadership assessment tool was developed using literature review and local expertise and then piloted and refined using medical simulation. Pediatric emergency medicine (PEM) fellows from a single tertiary care pediatric medical center were enrolled, and videos of one medical resuscitation and one trauma resuscitation were collected per fellow each month. Three reviewers underwent reviewer training and then scored the videos using the assessment tool. Raters provided feedback on feasibility and ease of use using a 5-point Likert scale. Inter-rater reliability for the assessment tool using Gwet's agreement coefficient and the association between performance and clinical level of training using generalized linear mixed model were calculated. Results: Twelve PEM fellows enrolled and 146 videos were reviewed. The inter-rater reliability for each domain ranged from 0.45 (p < 0.0001) to 0.59 (p < 0.0001), with the inter-rater reliability of the total score being 0.49 (p < 0.0001). The reviewers' mean ratings of the elements of the tool were as follows: clarity of the domains (4.6/5), the independence of each domain from each other (3.9/5), the ease of use of the 5-point Likert scale (4.5/5), the usefulness of the provided examples for each domain (4.6/5), and the ability to assess each domain without having to rewatch (4.5/5). The tool differentiated between levels of clinical training for two of the six domains (p < 0.02). Conclusions: We developed a novel team leadership assessment tool for pediatric resuscitation team leaders that demonstrated moderate inter-rater reliability. The tool was easy to use and feasible for educators to assess the performance of PEM trainees in complex high-stakes clinical situations.

Paediatric resident identification of cardiac emergencies.

OBJECTIVES: Critical CHD is associated with morbidity and mortality, worsened by delayed diagnosis. Paediatric residents are front-line clinicians, yet identification of congenital CHD remains challenging. Current exposure to cardiology is limited in paediatric resident education. We evaluated the impact of rapid cycle deliberate practice simulation on paediatric residents' skills, knowledge, and perceived competence to recognise and manage infants with congenital CHD. METHODS: We conducted a 6-month pilot study. Interns rotating in paediatric cardiology completed a case scenario assessment during weeks 1 and 4 and participated in paired simulations (traditional debrief and rapid cycle deliberate practice) in weeks 2-4. We assessed interns' skills during the simulation using a checklist of "cannot miss" tasks. In week 4, they completed a retrospective pre-post knowledge-based survey. We analysed the data using summary statistics and mixed effect linear regression. RESULTS: A total of 26 interns participated. There was a significant increase in case scenario assessment scores between weeks 1 and 4 (4, interquartile range 3-6 versus 8, interquartile range 6-10; p-value < 0.0001). The percentage of "cannot miss" tasks on the simulation checklist increased from weeks 2 to 3 (73% versus 83%, p-value 0.0263) and from weeks 2-4 (73% versus 92%, p-value 0.0025). The retrospective pre-post survey scores also increased (1.67, interquartile range 1.33-2.17 versus 3.83, interquartile range 3.17-4; p-value < 0.0001). CONCLUSION: Rapid cycle deliberate practice simulations resulted in improved recognition and initiation of treatment of simulated infants with congenital CHD among paediatric interns. Future studies will include full implementation of the curriculum and knowledge retention work.

High ploidy large cytoplasmic megakaryocytes are hematopoietic stem cells regulators and essential for platelet production.

Megakaryocytes (MK) generate platelets. Recently, we and others, have reported MK also regulate hematopoietic stem cells (HSC). Here we show high ploidy large cytoplasmic megakaryocytes (LCM) are critical negative regulators of HSC and critical for platelet formation. Using a mouse knockout model (Pf4-Srsf3Δ/Δ) with normal MK numbers, but essentially devoid of LCM, we demonstrate a pronounced increase in BM HSC concurrent with endogenous mobilization and extramedullary hematopoiesis. Severe thrombocytopenia is observed in animals with diminished LCM, although there is no change in MK ploidy distribution, uncoupling endoreduplication and platelet production. When HSC isolated from a microenvironment essentially devoid of LCM reconstitute hematopoiesis in lethally irradiated mice, the absence of LCM increases HSC in BM, blood and spleen, and the recapitulation of thrombocytopenia. In contrast, following a competitive transplant using minimal numbers of WT HSC together with HSC from a microenvironment with diminished LCM, sufficient WT HSC-generated LCM regulates a normal HSC pool and prevents thrombocytopenia. Importantly, LCM are conserved in humans.

Development and implementation of a paediatric cardiac intensive care advanced practice provider curriculum.

BACKGROUND: Education of paediatric advanced practice providers takes a generalist approach which lacks in-depth exposure to subspecialties like paediatric cardiac intensive care. This translates into a knowledge gap related to congenital cardiac physiology and management for APPs transitioning to the paediatric cardiac ICU. METHODS: A specialised interprofessional peer-reviewed curriculum was created and distributed through the Pediatric Cardiac Intensive Care Society. This curriculum includes a textbook which is complemented by a didactic and simulation review course. Course evaluations were collected following each course, and feedback from participants was incorporated into subsequent courses. Pediatric Cardiac Intensive Care Society partnered with the Pediatric Nursing Certification Board to develop a 200-question post-assessment (exam) bank. RESULTS: From December 2017 to January 2022, 12 review courses were taught at various host sites (n = 314 participants). Feedback revealed that courses improved preparedness for practice, contributed to advanced practice provider empowerment, and emphasised the importance of professional networking. 97% of attendees agreed/strongly agreed that the course improved clinical knowledge, 97% agreed/strongly agreed that the course improved ability to care for patients, and 88% agreed/strongly agreed that the course improved confidence to practice. 49% of participants rated the course as extremely effective, 42% very effective, 6% moderately effective, and 3% as only slightly effective. CONCLUSIONS: A standardised subspecialty curriculum dedicated to advanced practice provider practice in cardiac intensive care was needed to improve knowledge, advance practice, and empower APPs managing critically ill patients in the cardiac ICU. The developed curriculum provides standardised learning, increasing advanced practice provider knowledge acquisition, and confidence to practice.

Safety and immunogenicity of a synthetic multiantigen modified vaccinia virus Ankara-based COVID-19 vaccine (COH04S1): an open-label and randomised, phase 1 trial.

Background: COH04S1, a synthetic attenuated modified vaccinia virus Ankara vector co-expressing SARS-CoV-2 spike and nucleocapsid antigens, was tested for safety and immunogenicity in healthy adults. Methods: This combined open-label and randomised, phase 1 trial was done at the City of Hope Comprehensive Cancer Center (Duarte, CA, USA). We included participants aged 18-54 years with a negative SARS-CoV-2 antibody and PCR test, normal haematology and chemistry panels, a normal electrocardiogram and troponin concentration, negative pregnancy test if female, body-mass index of 30 kg/m2 or less, and no modified vaccinia virus Ankara or poxvirus vaccine in the past 12 months. In the open-label cohort, 1·0 × 107 plaque-forming units (PFU; low dose), 1·0 × 108 PFU (medium dose), and 2·5 × 108 PFU (high dose) of COH04S1 were administered by intramuscular injection on day 0 and 28 to sentinel participants using a queue-based statistical design to limit risk. In a randomised dose expansion cohort, additional participants were randomly assigned (3:3:1), using block size of seven, to receive two placebo vaccines (placebo group), one low-dose COH04S1 and one placebo vaccine (low-dose COH04S1 plus placebo group), or two low-dose COH04S1 vaccines (low-dose COH04S1 group). The primary outcome was safety and tolerability, with secondary objectives assessing vaccine-specific immunogenicity. The primary immunological outcome was a four times increase (seroconversion) from baseline in spike-specific or nucleocapsid-specific IgG titres within 28 days of the last injection, and seroconversion rates were compared with participants who received placebo using Fisher's exact test. Additional secondary outcomes included assessment of viral neutralisation and cellular responses. This trial is registered with ClinicalTrials.gov, NCT046339466. Findings: Between Dec 13, 2020, and May 24, 2021, 56 participants initiated vaccination. On day 0 and 28, 17 participants received low-dose COH04S1, eight received medium-dose COH04S1, nine received high-dose COH04S1, five received placebo, 13 received low-dose COH04S1 followed by placebo, and four discontinued early. Grade 3 fever was observed in one participant who received low-dose COH04S1 and placebo, and grade 2 anxiety or fatigue was seen in one participant who received medium-dose COH04S1. No severe adverse events were reported. Seroconversion was observed in all 34 participants for spike protein and 32 (94%) for nucleocapsid protein (p<0·0001 vs placebo for each comparison). Four times or more increase in SARS-CoV-2 neutralising antibodies within 56 days was measured in nine of 17 participants in the low-dose COH04S1 group, all eight participants in the medium-dose COH04S1 group, and eight of nine participants in the high-dose COH04S1 group (p=0·0035 combined dose levels vs placebo). Post-prime and post-boost four times increase in spike-specific or nucleocapsid-specific T cells secreting interferon-γ was measured in 48 (98%; 95% CI 89-100) of 49 participants who received at least one dose of COH04S1 and provided a sample for immunological analysis. Interpretation: COH04S1 was well tolerated and induced spike-specific and nucleocapsid-specific antibody and T-cell responses. Future evaluation of this COVID-19 vaccine candidate as a primary or boost vaccination is warranted. Funding: The Carol Moss Foundation and City of Hope Integrated Drug Development Venture programme.

Building the foundation of health-related knowledge via near-peer education for children with sickle cell disease.

Health education for children with chronic illnesses (i.e., sickle cell disease [SCD]) has focused on educating adult caregivers with minimal consideration to educating the pediatric patients. We introduce a pediatric-focused educational paradigm, health-related knowledge (HRK), teaching pediatric patients developmentally appropriate general health literacy, and disease-specific knowledge. Using science, technology, engineering, and mathematics (STEM) education concepts, pediatric-specific HRK interactive activities address educational gaps: (a) general STEM education; and (b) general health and disease-specific knowledge to improve clinical outcomes. Total 144 pediatric SCD patients completed HRK activities, revealing overwhelmingly positive feedback (87%). Seventy-five percent of participants in 6th grade and above demonstrated thorough understanding of the STEM/HRK topics taught.

The RNA-binding protein SRSF3 has an essential role in megakaryocyte maturation and platelet production.

RNA processing is increasingly recognized as a critical control point in the regulation of different hematopoietic lineages including megakaryocytes responsible for the production of platelets. Platelets are anucleate cytoplasts that contain a rich repertoire of RNAs encoding proteins with essential platelet functions derived from the parent megakaryocyte. It is largely unknown how RNA binding proteins contribute to the development and functions of megakaryocytes and platelets. We show that serine-arginine-rich splicing factor 3 (SRSF3) is essential for megakaryocyte maturation and generation of functional platelets. Megakaryocyte-specific deletion of Srsf3 in mice led to macrothrombocytopenia characterized by megakaryocyte maturation arrest, dramatically reduced platelet counts, and abnormally large functionally compromised platelets. SRSF3 deficient megakaryocytes failed to reprogram their transcriptome during maturation and to load platelets with RNAs required for normal platelet function. SRSF3 depletion led to nuclear accumulation of megakaryocyte mRNAs, demonstrating that SRSF3 deploys similar RNA regulatory mechanisms in megakaryocytes as in other cell types. Our study further suggests that SRSF3 plays a role in sorting cytoplasmic megakaryocyte RNAs into platelets and demonstrates how SRSF3-mediated RNA processing forms a central part of megakaryocyte gene regulation. Understanding SRSF3 functions in megakaryocytes and platelets provides key insights into normal thrombopoiesis and platelet pathologies as SRSF3 RNA targets in megakaryocytes are associated with platelet diseases.

Bone Marrow Regulatory T Cells Are a Unique Population, Supported by Niche-Specific Cytokines and Plasmacytoid Dendritic Cells, and Required for Chronic Graft-Versus-Host Disease Control.

Regulatory T cell (Treg) reconstitution is essential for reestablishing tolerance and maintaining homeostasis following stem-cell transplantation. We previously reported that bone marrow (BM) is highly enriched in autophagy-dependent Treg and autophagy disruption leads to a significant Treg loss, particularly BM-Treg. To correct the known Treg deficiency observed in chronic graft-versus-host disease (cGVHD) patients, low dose IL-2 infusion has been administered, substantially increasing peripheral Treg (pTreg) numbers. However, as clinical responses were only seen in ∼50% of patients, we postulated that pTreg augmentation was more robust than for BM-Treg. We show that BM-Treg and pTreg have distinct characteristics, indicated by differential transcriptome expression for chemokine receptors, transcription factors, cell cycle control of replication and genes linked to Treg function. Further, BM-Treg were more quiescent, expressed lower FoxP3, were highly enriched for co-inhibitory markers and more profoundly depleted than splenic Treg in cGVHD mice. In vivo our data are consistent with the BM and not splenic microenvironment is, at least in part, driving this BM-Treg signature, as adoptively transferred splenic Treg that entered the BM niche acquired a BM-Treg phenotype. Analyses identified upregulated expression of IL-9R, IL-33R, and IL-7R in BM-Treg. Administration of the T cell produced cytokine IL-2 was required by splenic Treg expansion but had no impact on BM-Treg, whereas the converse was true for IL-9 administration. Plasmacytoid dendritic cells (pDCs) within the BM also may contribute to BM-Treg maintenance. Using pDC-specific BDCA2-DTR mice in which diptheria toxin administration results in global pDC depletion, we demonstrate that pDC depletion hampers BM, but not splenic, Treg homeostasis. Together, these data provide evidence that BM-Treg and splenic Treg are phenotypically and functionally distinct and influenced by niche-specific mediators that selectively support their respective Treg populations. The unique properties of BM-Treg should be considered for new therapies to reconstitute Treg and reestablish tolerance following SCT.

Nicotinamide riboside attenuates age-associated metabolic and functional changes in hematopoietic stem cells.

With age, hematopoietic stem cells (HSC) undergo changes in function, including reduced regenerative potential and loss of quiescence, which is accompanied by a significant expansion of the stem cell pool that can lead to haematological disorders. Elevated metabolic activity has been implicated in driving the HSC ageing phenotype. Here we show that nicotinamide riboside (NR), a form of vitamin B3, restores youthful metabolic capacity by modifying mitochondrial function in multiple ways including reduced expression of nuclear encoded metabolic pathway genes, damping of mitochondrial stress and a decrease in mitochondrial mass and network-size. Metabolic restoration is dependent on continuous NR supplementation and accompanied by a shift of the aged transcriptome towards the young HSC state, more youthful bone marrow cellular composition and an improved regenerative capacity in a transplant setting. Consequently, NR administration could support healthy ageing by re-establishing a more youthful hematopoietic system.

Combined Anti-inflammatory and Neuroprotective Treatments Have the Potential to Impact Disease Phenotypes in Cln3 -/- Mice.

Batten disease, or juvenile NCL, is a fatal neurodegenerative disorder that occurs due to mutations in the CLN3 gene. Because the function of CLN3 remains unclear, experimental therapies for JNCL have largely concentrated upon the targeting of downstream pathomechanisms. Neuron loss is preceded by localized glial activation, and in this proof-of-concept study we have investigated whether targeting this innate immune response with ibuprofen in combination with the neuroprotective agent lamotrigine improves the previously documented beneficial effects of immunosuppressants alone. Drugs were administered daily to symptomatic Cln3 -/- mice over a 3 month period, starting at 6 months of age, and their impact was assessed using both behavioral and neuropathological outcome measures. During the treatment period, the combination of ibuprofen and lamotrigine significantly improved the performance of Cln3 -/- mice on the vertical pole test, slowing the disease-associated decline, but had less of an impact upon their rotarod performance. There were also moderate and regionally dependent effects upon astrocyte activation that were most pronounced for ibuprofen alone, but there was no overt effect upon microglial activation. Administering such treatments for longer periods will enable testing for any impact upon the neuron loss that occurs later in disease progression. Given the partial efficacy of these treatments, it will be important to test further drugs of this type in order to find more effective combinations.

Mouse Hematopoietic Stem Cell Modification and Labelling by Transduction and Tracking Posttransplantation.

The tracking of the hematopoietic potential of genetically manipulated fluorescent hematopoietic stem cells (HSC) in the bone marrow (BM) allows the assessment of regulatory processes involved in the re-establishment of hematopoiesis posttransplant. Herein, we describe the means to assess the consequence of expressing specific genes in HSC on their engraftment potential posttransplant.

Simulation Training Improves Resuscitation Team Leadership Skills of Nurse Practitioners.

INTRODUCTION: In the current era of limited physician trainee work hours, limited nurse practitioner orientation times, and highly specialized care settings, frontline providers have limited opportunities for mentored resuscitation training in emergency situations. We aimed to evaluate the effectiveness of a pilot program to improve resuscitation team leadership skills of nurse practitioners using simulation-based training. METHODS: Seven nurse practitioners underwent a 4-hour simulation course in pediatric cardiac emergencies. Pre- and post-course surveys were conducted to evaluate previous emergency leadership experience and self-reported comfort in the team lead role. The time to verbalization of a shared mental model to the team was tracked during the simulations. RESULTS: The increases in self-reported comfort level in team leading, sharing a mental model, and differential diagnosis were statistically significant. Average time to shared mental model significantly decreased between simulations. DISCUSSION: Simulation can improve code leadership skills of nurse practitioners. These preliminary findings require confirmation in larger studies.

Compromised astrocyte function and survival negatively impact neurons in infantile neuronal ceroid lipofuscinosis.

The neuronal ceroid lipofuscinoses (NCLs) are the most common cause of childhood dementia and are invariably fatal. Early localized glial activation occurs in these disorders, and accurately predicts where neuronal loss is most pronounced. Recent evidence suggests that glial dysfunction may contribute to neuron loss, and we have now explored this possibility in infantile NCL (INCL, CLN1 disease). We grew primary cultures of astrocytes, microglia, and neurons derived from Ppt1 deficient mice (Ppt1-/-) and assessed their properties compared to wildtype (WT) cultures, before co-culturing them in different combinations (astrocytes with microglia, astrocytes or microglia with neurons, all three cell types together). These studies revealed that both Ppt1-/- astrocytes and microglia exhibit a more activated phenotype under basal unstimulated conditions, as well as alterations to their protein expression profile following pharmacological stimulation. Ppt1- /- astrocytes also displayed abnormal calcium signalling and an elevated cytoplasmic Ca2+ level, and a profound defect in their survival. Ppt1-/- neurons displayed decreased neurite outgrowth, altered complexity, a reduction in cell body size, and impaired neuron survival with prolonged time in culture. In co-cultures, the presence of both astrocytes and microglia from Ppt1-/- mice further impaired the morphology of both wild type and Ppt1-/- neurons. This negative influence was more pronounced for Ppt1-/- microglia, which appeared to trigger increased Ppt1-/- neuronal death. In contrast, wild type glial cells, especially astrocytes, ameliorated some of the morphological defects observed in Ppt1-/- neurons. These findings suggest that both Ppt1-/- microglia and astrocytes are dysfunctional and may contribute to the neurodegeneration observed in CLN1 disease. However, the dysfunctional phenotypes of Ppt1-/- glia are different from those present in CLN3 disease, suggesting that the pathogenic role of glia may differ between NCLs.

Cell Type of Origin Dictates the Route to Pluripotency.

Our current understanding of induced pluripotent stem cell (iPSC) generation has almost entirely been shaped by studies performed on reprogramming fibroblasts. However, whether the resulting model universally applies to the reprogramming process of other cell types is still largely unknown. By characterizing and profiling the reprogramming pathways of fibroblasts, neutrophils, and keratinocytes, we unveil that key events of the process, including loss of original cell identity, mesenchymal to epithelial transition, the extent of developmental reversion, and reactivation of the pluripotency network, are to a large degree cell-type specific. Thus, we reveal limitations for the use of fibroblasts as a universal model for the study of the reprogramming process and provide crucial insights about iPSC generation from alternative cell sources.

Glial cells are functionally impaired in juvenile neuronal ceroid lipofuscinosis and detrimental to neurons.

The neuronal ceroid lipofuscinoses (NCLs or Batten disease) are a group of inherited, fatal neurodegenerative disorders of childhood. In these disorders, glial (microglial and astrocyte) activation typically occurs early in disease progression and predicts where neuron loss subsequently occurs. We have found that in the most common juvenile form of NCL (CLN3 disease or JNCL) this glial response is less pronounced in both mouse models and human autopsy material, with the morphological transformation of both astrocytes and microglia severely attenuated or delayed. To investigate their properties, we isolated glia and neurons from Cln3-deficient mice and studied their basic biology in culture. Upon stimulation, both Cln3-deficient astrocytes and microglia also showed an attenuated ability to transform morphologically, and an altered protein secretion profile. These defects were more pronounced in astrocytes, including the reduced secretion of a range of neuroprotective factors, mitogens, chemokines and cytokines, in addition to impaired calcium signalling and glutamate clearance. Cln3-deficient neurons also displayed an abnormal organization of their neurites. Most importantly, using a co-culture system, Cln3-deficient astrocytes and microglia had a negative impact on the survival and morphology of both Cln3-deficient and wildtype neurons, but these effects were largely reversed by growing mutant neurons with healthy glia. These data provide evidence that CLN3 disease astrocytes are functionally compromised. Together with microglia, they may play an active role in neuron loss in this disorder and can be considered as potential targets for therapeutic interventions.

Knockdown of the schizophrenia susceptibility gene TCF4 alters gene expression and proliferation of progenitor cells from the developing human neocortex.

BACKGROUND: Common variants in the TCF4 gene are among the most robustly supported genetic risk factors for schizophrenia. Rare TCF4 deletions and loss-of-function point mutations cause Pitt-Hopkins syndrome, a developmental disorder associated with severe intellectual disability. METHODS: To explore molecular and cellular mechanisms by which TCF4 perturbation could interfere with human cortical development, we experimentally reduced the endogenous expression of TCF4 in a neural progenitor cell line derived from the developing human cerebral cortex using RNA interference. Effects on genome-wide gene expression were assessed by microarray, followed by Gene Ontology and pathway analysis of differentially expressed genes. We tested for genetic association between the set of differentially expressed genes and schizophrenia using genome-wide association study data from the Psychiatric Genomics Consortium and competitive gene set analysis (MAGMA). Effects on cell proliferation were assessed using high content imaging. RESULTS: Genes that were differentially expressed following TCF4 knockdown were highly enriched for involvement in the cell cycle. There was a nonsignificant trend for genetic association between the differentially expressed gene set and schizophrenia. Consistent with the gene expression data, TCF4 knockdown was associated with reduced proliferation of cortical progenitor cells in vitro. LIMITATIONS: A detailed mechanistic explanation of how TCF4 knockdown alters human neural progenitor cell proliferation is not provided by this study. CONCLUSION: Our data indicate effects of TCF4 perturbation on human cortical progenitor cell proliferation, a process that could contribute to cognitive deficits in individuals with Pitt-Hopkins syndrome and risk for schizophrenia.

Differentiation of human embryonic stem cells to HOXA+ hemogenic vasculature that resembles the aorta-gonad-mesonephros.

The ability to generate hematopoietic stem cells from human pluripotent cells would enable many biomedical applications. We find that hematopoietic CD34+ cells in spin embryoid bodies derived from human embryonic stem cells (hESCs) lack HOXA expression compared with repopulation-competent human cord blood CD34+ cells, indicating incorrect mesoderm patterning. Using reporter hESC lines to track the endothelial (SOX17) to hematopoietic (RUNX1C) transition that occurs in development, we show that simultaneous modulation of WNT and ACTIVIN signaling yields CD34+ hematopoietic cells with HOXA expression that more closely resembles that of cord blood. The cultures generate a network of aorta-like SOX17+ vessels from which RUNX1C+ blood cells emerge, similar to hematopoiesis in the aorta-gonad-mesonephros (AGM). Nascent CD34+ hematopoietic cells and corresponding cells sorted from human AGM show similar expression of cell surface receptors, signaling molecules and transcription factors. Our findings provide an approach to mimic in vitro a key early stage in human hematopoiesis for the generation of AGM-derived hematopoietic lineages from hESCs.

Haemopedia: An Expression Atlas of Murine Hematopoietic Cells.

Hematopoiesis is a multistage process involving the differentiation of stem and progenitor cells into distinct mature cell lineages. Here we present Haemopedia, an atlas of murine gene-expression data containing 54 hematopoietic cell types, covering all the mature lineages in hematopoiesis. We include rare cell populations such as eosinophils, mast cells, basophils, and megakaryocytes, and a broad collection of progenitor and stem cells. We show that lineage branching and maturation during hematopoiesis can be reconstructed using the expression patterns of small sets of genes. We also have identified genes with enriched expression in each of the mature blood cell lineages, many of which show conserved lineage-enriched expression in human hematopoiesis. We have created an online web portal called Haemosphere to make analyses of Haemopedia and other blood cell transcriptional datasets easier. This resource provides simple tools to interrogate gene-expression-based relationships between hematopoietic cell types and genes of interest.

Therapeutic targeting and rapid mobilization of endosteal HSC using a small molecule integrin antagonist.

The inherent disadvantages of using granulocyte colony-stimulating factor (G-CSF) for hematopoietic stem cell (HSC) mobilization have driven efforts to identify alternate strategies based on single doses of small molecules. Here, we show targeting α9ß1/α4ß1 integrins with a single dose of a small molecule antagonist (BOP (N-(benzenesulfonyl)-L-prolyl-L-O-(1-pyrrolidinylcarbonyl)tyrosine)) rapidly mobilizes long-term multi-lineage reconstituting HSC. Synergistic engraftment augmentation is observed when BOP is co-administered with AMD3100. Impressively, HSC in equal volumes of peripheral blood (PB) mobilized with this combination effectively out-competes PB mobilized with G-CSF. The enhanced mobilization observed using BOP and AMD3100 is recapitulated in a humanized NODSCIDIL2Rγ(-/-) model, demonstrated by a significant increase in PB CD34(+) cells. Using a related fluorescent analogue of BOP (R-BC154), we show that this class of antagonists preferentially bind human and mouse HSC and progenitors via endogenously primed/activated α9ß1/α4ß1 within the endosteal niche. These results support using dual α9ß1/α4ß1 inhibitors as effective, rapid and transient mobilization agents with promising clinical applications.