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Megakaryopoiesis hierarchy and its regulation by the cellular microenvironment.

Research unit

UMR_S 949 - Biologie et pharmacologie des plaquettes sanguines : hémostase, thrombose, transfusion (BPPS)
10, rue Spielmann - BP 36 67065 Strasbourg Cedex

Group

Name: Biologie de la thrombopoièse

Group leader: LANZA François - fancois.lanza@efs.sante.fr

Group leader's phone: 0388212525

Website: Visit website

Group organization:
- Chercheurs: 6
- ITA: 5
- Doctorants: 3
- Post-Docs: 1
- Autres: 5

Publications of the team linked to the topic (3 last years):
1) Strassel C., Brouard N., Mallo L., Receveur N., Mangin P., Eckly A., Ivan Bieche I, Tarte K., Gachet C. and Lanza F.Aryl hydrocarbon receptor-dependent enrichment of a megakaryocytic precursor with a high potential to produce proplatelets Blood (2016) Accepted for publication
2) Strassel C, Eckly A, Léon C, Moog S, Cazenave JP, Gachet C, Lanza F. Hirudin and heparin enable efficient megakaryocyte differentiation of mouse bone marrow progenitors. Exp Cell Res. 2012 ;318(1):25-32.
3) Eckly A, Heijnen H, Pertuy F, Geerts W, Proamer F, Rinckel JY, Léon C, Lanza F, Gachet C. Biogenesis of the demarcation membrane system (DMS) in megakaryocytes. Blood. 2014;123(6):921-30.

About PhD

PhD Director: LANZA François - fancois.lanza@efs.sante.fr

Phone: 0388212525

Junior advisor: BROUARD Nathalie

Co-tutely: non

Co-Director: non

About PhD topic :

Title: Megakaryopoiesis hierarchy and its regulation by the cellular microenvironment.

Project: Platelets are key elements of hemostasis. Some pathologies and treatments lead to alteration in platelets numbers or in their function. Transfusion of blood platelets is treatment of choice to maintain homeostasis. The increasing needs for blood platelets, and their short shelf life creates frequently situation of risk of shortage resulting in high pressure on the logistic networks. It is therefore necessary to consider means to produce platelets in vitro. So far, platelets production in vitro is restricted to the research laboratory and is poorly efficient and by no means in a range sufficient for large scale production of platelets suitable for transfusion. Consequently the aim of this project is to better understand the mechanisms involved in the production of platelets in order to improve the production of platelets in vitro. Platelets are produced by larges specialized cells in the bone marrow : megakaryocytes (MK). Hematopoietic stem cells (HSC) are the source of all blood cell lineages, and most specifically MK. Megakaryopoiesis is the complex process leading to the production of MK from HSC. HSC produce hematopoietic progenitors that progressively commit toward the megakaryocytic lineage through phases of proliferation, differentiation and maturation in order to produce mature MK capable of releasing in the blood circulation the 1011 platelets needed daily. During every phase from HSC to mature MK shedding platelets in the blood circulation, hematopoietic cells are in contact with a specific microenvironment that regulates each step. The microenvironment is constituted of cellular elements (stromal cells, endothelial cells), non cellular elements (extracellular matrix, growth factors, cytokines, calcium, oxygen), but also mechanical forces (blood flow, elasticity). During megakaryopoiesis, MK progenitors are in contact with successive microenvironments that control their differentiation and maturation. The fetal liver is a transient site of production of blood cells, before the establishment of definitive hematopoiesis in the bone marrow. Preliminary results obtained in our laboratory have shown that the fetal liver contain several populations of stromal cells, including one that support the production of MK from HSC. The other stromal cell population tend to inhibit the differentiation of HSC to MK, but are still providing a suitable support for progenitors committed to the MK lineage.
This project goal is first to understand how hepatic microenvironment can regulate the commitment of HSC towards MK lineage and secondly to investigate how the microenvironment can by of use to improve the production of platelets in vitro. We will evaluate in vitro the role of the various cellular component of the microenvironment during expansion and differentiation of MK. An update of the hematopoietic hierachy during megakaryopoiesis willa also be performed. Hematopoietic, stromal and endothelial cells will be sorted using flow cytometry and cultivated in coculture systems established in our laboratory in order to evaluate the role of each cell type during development. We will determine the mechanism of action of stromal cell in the regulation of megakaryopoiesis (secretion of specific factors, cell-cell contact interactions). Molecular analysis of the cells of interest (transcriptomic and proteomic analysis) will be performed to identify the secreted proteins or proteins expressed at the surface of the functional microenvironment of megakaryopoiesis.
All techniques necessary for the success of this project are currently applied in the laboratory.

Wished skills: Basic knowledges in Molecular and Cell Biology

Expertises which will be acquired during the training: The project will allow acquiring a large panel of expertise namely: - Analysis of hematopoietic stem cells – enzymatic and mechanic dissociation of tissues, culture of progenitors, organotypic culture – basic techniques in molecular biology (production of vectors, cell transfection, RT-PCR, q-PCR) – cell transplantation in animal models – flow cytometry (analysis and cell sorting) – Histology (immunohistochemistry and immunofluorescence) – Analysis in confocal microscopy