Cellular characterization of hematopoietic system and hematopoietic niches in murine model of sickle cell anemia

Author(s)

Felipe Augusto Rós

• Document type: Master's Dissertation
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC)
• Defense date: 2021-07-07

Examining board members

Simone Kashima Haddad; Ana Cristina Silva Pinto; Vanderson Geraldo Rocha

• Advisor: Simone Kashima Haddad; Renato Luiz Guerino Cunha

Abstract

The hematopoietic system is responsible for the production of blood cells in the body in homeostasis or stress. Its functioning depends on the maintenance and coordinated differentiation of hematopoietic stem cells (HSC), which are closely associated with the hematopoietic niche. The hematopoietic niche is a highly dynamic microenvironment, orchestrated and heterogeneous in terms of its cellular composition. Among the cell types that make up the niche are the endothelial cells and multipotent mesenchymal stromal cells (MSC) that together with the other components support and regulate the self-renewal and differentiation of HSC. However, hematological diseases can alter the hematopoietic system, the HSC and other cells in the microenvironment Therefore, this study analyzed the hematopoiesis, intramedullary and extramedullary splenic hematopoietic niches and bone marrow (BM) MSCs of sickle-cell mice (Townes-SS) at different ages and after treatment with Hydroxyurea (HU). The results revealed a greater number of erythrocyte-megakaryocyte progenitor megakaryocytic-erythroid progenitors (MEP) in the intramedullary niche of the Townes-SS, in addition to a greater number of: HSC, common myeloid progenitors (CMP), granulocyte-monocyte progenitors (GMP) and MEP in the extramedullary niche splenic. These findings demonstrate that the combined analysis of intra and extramedullary splenic hematopoiesis of the Townes-SS agrees with data already described for OM in humans. The increase in MEP was accompanied by an increase in the frequency of total terminal erythroid progenitors and an alteration in the mitotic profile of the murine terminal erythroid differentiation in both niches. The analysis of non-hematopoietic cells revealed a greater number of endothelial stem cells, MSC and non-mesenchymal stromal cells in the splenic extramedullary niche. The analysis of isolated and in vitro cultivated OM MSCs did not show morphofunctional differences, except for a transcriptional profile related to increased HSC differentiation at the expense of quiescence maintenance. Finally, the treatment of Townes-SS with HU resulted in a lower number of HSC, CMP, GMP and MEP in the intramedullary and extramedullary splenic hematopoietic niches of treated animals compared to untreated ones. This cellular behavior agrees again with data already described in humans who use HU compared to those who do not use it. Therefore, the results obtained demonstrate that the Townes-SS can be used as an animal model for preclinical or basic science studies that assess the impacts of FA on HSC and other hematopoietic or non-hematopoietic cells of hematopoietic niches, as well as in tests on the effect of drugs and drugs on hematopoiesis, hematopoietic niche and specific cells in the context of FA. (AU)

• FAPESP's process: 19/22155-2 - Cellular characterization of hematopoietic niches in murine model of sickle cell anemia
• Grantee: Felipe Augusto Rós
• Support Opportunities: Scholarships in Brazil - Master