Biogenesis and bioengineering of human platelets (360G-Wellcome-219472_A_19_Z)

Platelets are essential for haemostasis and play critical roles in innate immunity, angiogenesis and tissue repair. They are derived from megakaryocytes, each of which generates several thousand platelets. A major goal is to generate platelets in vitro, to address shortage of platelet supply for transfusion, and to enable fundamental discovery of gene function. To date, however, only very small numbers (approximately 10 per megakaryocyte) of platelets can be made in vitro. We propose a step change using novel in vitrosystems, to increase generation efficiency by 1-2 orders of magnitude. We will use two in vitrosystems (mouse lung vasculature and microcirculation microfluidics) using forward-programmed iPSC-derived megakaryocytes. Our new data show that passage of megakaryocytes through lung vasculature ‘educates’ them to undergo a sequence of changes: reversible deformation, enucleation and abscission to release platelets. We aim to understand the detailed biology of these processes using CRISPR-edited megakaryocytes. We also show we can make human platelets in our novel microfluidic system and will optimize this to bioengineer large quantities of cells, by learning from the biology of the ex vivolung preparation. This is potentially transformative for fundamental understanding of human platelets and megakaryocytes, and for their bioengineering for clinical uses.