Defining the mechanics driving platelet formation via megakaryocyte membrane budding

Over a hundred years after megakaryocytes were first described as the source of platelets, the exact mechanism by which megakaryocytes produce platelets remains incompletely understood. Currently, three theories exist to explain platelet biogenesis: proplatelet formation, cellular fragmentation, and plasma membrane budding. The aim of this research project was to investigate the mechanics of one of these theories, a novel model of platelet production termed megakaryocyte membrane budding, in hopes of filling this century-old gap in knowledge. This project aimed to explore membrane budding by examining the involvement of microtubules and the actin cytoskeleton at the plasma membrane during bud formation. Using immunofluorescence microscopy of the adult mouse bone marrow, I first investigated the relevance of budding to platelet production with a robust analysis of bud contents and morphology. Next, I investigated the involvement of key cytoskeletal proteins at the different stages of budding in healthy steady-state, and identified a pathway whereby components of the cytoskeleton become sequentially involved at each step. Finally, I was able to gain a more rigorous understanding of the mechanics and relevance of membrane budding by the study of multiple mutant mouse models. With these new insights, I aimed to guide fresh developments in the field of ex vivo platelet manufacture, having major impacts on platelet transfusions, personalised medicine and beyond.