Biology subjects

Pinto-do-O, P.

Publications and source records attributed to Pinto-do-O, P..

4 recordsLinked to original sources

bioRxiv2024

FLT3 is genetically essential for ITD-mutated leukemic stem cells but dispensable for human hematopoietic stem cells

Leukemic stem cells (LSCs) fuel acute myeloid leukemia (AML) growth and relapse, but therapies tailored towards eradicating LSCs without harming healthy hematopoietic stem cells (HSCs) are lacking. FLT3 is considered an important therapeutic target due to frequent mutation in AML and association with relapse. However, there has been limited clinical success with FLT3 targeting, suggesting either that FLT3 is not a vulnerability in LSC, or that more potent inhibition is required, a scenario where HSC toxicity could become limiting. We tested these possibilities by ablating FLT3 using CRISPR/Cas9-mediated FLT3 knock-out (FLT3-KO) in human LSCs and HSCs followed by functional xenograft assays. FLT3-KO in LSCs from FLT3-ITD mutated, but not FLT3-WT AMLs, resulted in short-term leukemic grafts of FLT-3-KO edited cells that disappeared by 12 weeks. By contrast, FLT3-KO in HSCs from fetal liver, cord blood and adult bone marrow did not impair multilineage hematopoiesis in primary and secondary xenografts. Our study establishes FLT3 as an ideal therapeutic target where ITD+ LSC are eradicated upon FLT3 deletion, while HSCs are spared. These findings support the development of more potent FLT3-targeting drugs or gene-editing approaches for LSC eradication to improve clinical outcomes. KEY POINTSThe FLT3 gene is essential for ITD-mutated leukemic stem cells (LSCs) to establish and propagate leukemia. Normal human hematopoietic stem cells (HSCs) do not require FLT3 to engraft and sustain hematopoiesis. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/601363v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@b77f56org.highwire.dtl.DTLVardef@109011dorg.highwire.dtl.DTLVardef@282e04org.highwire.dtl.DTLVardef@1e51e3b_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Spatiotemporal dynamics of cytokines expression dictate fetal liver hematopoiesis.

During embryogenesis, yolk-sac and intra-embryonic-derived hematopoietic progenitors, comprising the precursors of adult hematopoietic stem cells, converge into the fetal liver. With a new staining strategy, we defined all non-hematopoietic components of the fetal liver and found that hepatoblasts are the major producers of hematopoietic growth factors. We identified mesothelial cells, a novel component of the stromal compartment, producing Kit ligand, a major hematopoietic cytokine. A high-definition imaging dataset analyzed using a deep-learning based pipeline allowed the unambiguous identification of hematopoietic and stromal populations, and enabled determining a neighboring network composition, at the single cell resolution. Throughout active hematopoiesis, progenitors preferentially associate with hepatoblasts, but not with stellate or endothelial cells. We found that, unlike yolk sac-derived progenitors, intra-embryonic progenitors respond to a chemokine gradient created by CXCL12-producing stellate cells. These results revealed that FL hematopoiesis is a spatiotemporal dynamic process, defined by an environment characterized by low cytokine concentrations.

developmental biology↗

bioRxiv2020

Yolk sac erythromyeloid progenitors sustain erythropoiesis throughout embryonic life

The first hematopoietic cells are produced in the yolk sac and are thought to be rapidly replaced by the progeny of hematopoietic stem cells. Here we document that hematopoietic stem cells do not contribute significantly to erythrocyte production up until birth. Lineage tracing of yolk sac-derived erythromyeloid progenitors, that also contribute to tissue resident macrophages, shows a progeny of highly proliferative erythroblasts, that after intra embryonic injection, rapidly differentiate. These progenitors, similar to hematopoietic stem cells, are c-Myb dependent and are developmentally restricted as they are not found in the bone marrow. We show that erythrocyte progenitors of yolk sac origin require lower concentrations of erythropoietin than their hematopoietic stem cell-derived counterparts for efficient erythrocyte production. Consequently, fetal liver hematopoietic stem cells fail to generate megakaryocyte and erythrocyte progenitors. We propose that large numbers of yolk sac-derived erythrocyte progenitors have a selective advantage and efficiently outcompete hematopoietic stem cell progeny in an environment with limited availability of erythropoietin.

developmental biology↗

bioRxiv2019

HSA+ immature cardiomyocytes persist in the adult heart and expand after ischemic injury

The assessment of the regenerative capacity of the heart has been compromised by the lack of surface signatures to characterize cardiomyocytes. Here, combined multiparametric surface marker analysis with single cell transcriptional profiling and in vivo transplantation, identify the main fetal cardiac populations and their progenitors. We found that cardiomyocytes at different stages of differentiation co-exist during development. We identified a population of immature HSA/CD24+ cardiomyocytes that persists throughout life and that, unlike other cardiomyocyte subsets, actively proliferates up to one week of age and engraft cardiac tissue upon transplantation. In adult heart HSA/CD24+ cardiomyocytes appear as mononucleated cells that cycle and increase in frequency after infarction. Our work identified cell surface signatures that allow the prospective isolation of cardiomyocytes at any developmental stage and the detection of adult cardiomyocytes poised for activation in response to ischemic stimuli. This work opens new perspectives in the understanding and treatment of heart pathologies.

developmental biology↗