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Aspects of angiogenesis in sickle cell disease: role of platelet

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Fernanda Camila Zauli Fabris
Total Authors: 1
Document type: Doctoral Thesis
Press: Campinas, SP.
Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Ciências Médicas
Defense date:
Examining board members:
Nicola Amanda Conran Zorzetto; Cristina Pontes Vicente; Rodolfo Delfini Cançado; Andrea Ribeiro Soares; Sara Teresinha Olalla Saad
Advisor: Nicola Amanda Conran Zorzetto

Sickle cell disease (SCD) is caused by a genetic mutation that results in the substitution of a single amino acid in the ?-globin chain, leading to the formation of an anomalous hemoglo-bin known as hemoglobin (HbS). At low blood oxygen concentrations, HbS polymerizes and red blood cells undergo sickling. Angiogenesis is the process by which the formation of new vessels occurs from pre-existing vessels. Previous studies have shown that patients with SCD have increased levels of plasma angiogenic factors, which indicates a proangio-genic state in these individuals, and that platelets from patients with sickle cell anemia (SCA) circulate in an activated state in the bloodstream. As platelets are known to serve as reservoirs for factors involved in inflammation and angiogenesis, the aim of this project was to evaluate the role of platelets from SCD patients in the major angiogenic mechanisms of endothelial cells in vitro, using Human Umbilical Vein Endothelial Cells (HUVEC). HU-VEC cells were co-cultured with platelets isolated from the peripheral blood of patients with SCA (HbSS) and SCD (HbSC), and from healthy individuals (HbAA) for 24 hours. The quantification of proliferating cells was carried out using a commercial kit (BrdU), and HUVEC were cultured in the presence and absence of platelets on GFR-Matrigel matrix to assess the formation of capillary-like structures by endothelial cells. Invasion and migration assays were performed in dual chamber plates using Matrigel, and the Scratch technique, respectively. The secretome and the expression of receptors on the surface of platelets were analyzed using multiplex assays and flow cytometry. Our data indicate that SCD and con-trol platelets can stimulate the formation of capillary structures, and the invasion and migra-tion of endothelial cells (EC), in vitro. Our findings also show that the co-cultivation of EC with SCA platelets, in the same well, results in increased EC invasiveness. SCA platelets were found to secrete, during a 24-hour period, increased levels of the pro-angiogenic fac-tors, Ang 1, angiogenin and PDGF-AA, and the anti-angiogenic factor endostatin, and pre-sented an increased expression of the PAR-1 thrombin receptor. Our work reinforces the hypothesis that platelets participate in the angiogenic process of SCA and provides perspec-tives for further studies. Given the increased circulating platelet counts associated with SCD, data further highlight the platelets as a therapeutic target for the treatment of SCD (AU)

FAPESP's process: 17/11601-6 - Aspects of angiogenesis in Sickle Cell Anemia: the role of platelets
Grantee:Fernanda Camila Zauli Fabris
Support Opportunities: Scholarships in Brazil - Doctorate (Direct)