ABSTRACT
The main function of blood platelets is to ensure hemostasis and prevent hemorrhages. The 1011 platelets needed daily are produced in a well-orchestrated process. However, this process is not yet fully understood and in vitro platelet production is still inefficient. Platelets are produced in the bone marrow by megakaryocytes, highly specialized precursor cells that extend cytoplasmic projections called proplatelets (PPTs) through the endothelial barrier of sinusoid vessels. In this Cell Science at a Glance article and the accompanying poster we discuss the mechanisms and pathways involved in megakaryopoiesis and platelet formation processes. We especially address the – still underestimated – role of the microenvironment of the bone marrow, and present recent findings on how PPT extension in vivo differs from that in vitro and entails different mechanisms. Finally, we recapitulate old but recently revisited evidence that – although bone marrow does produce megakaryocytes and PPTs – remodeling and the release of bona fide platelets, mainly occur in the downstream microcirculation.
Footnotes
Funding
J.B. is funded through a grant from Fondation pour la Recherche Médicale (FRM) (grant number: ECO20170637508). I.G. is founded through an Association Nationale pour la Recherche (ANR) grant (ANR-18-CE14-PlatForMechanics). Further work from the lab was also supported by APR-EFS (2016-LEON-ALS), ANR-17-CE14-MegaPlatProd, Etablissement Français du Sang, Institut National de la Santé et Recherche médicale (INSERM) and Association de Recherche et Développement en Médecine et Santé Publique (ARMESA).
