Highly efficient platelet generation in lung vasculature reproduced by microfluidics

Abstract Platelets, small hemostatic blood cells, are derived from megakaryocytes (MKs). It is accepted that both bone marrow (BM) and lung are principal sites of thrombogenesis although underlying mechanisms remain unclear. Outside the body, however, our ability to generate platelets, and retain their functionality, is poor at present. Here we show that perfusion of MKs ex vivo through the mouse lung vasculature generates substantial platelet numbers, up to 3,000 per MK. Despite their large size, MKs were able repeatedly to passage through the lung vasculature, leading to enucleation and subsequent platelet generation intravascularly. Using the ex vivo lung and a novel in vitro microfluidic chamber we determined how oxygenation, ventilation and endothelial cell health support platelet generation. Our data also show a critical role for the actin regulator TPM4 in the final steps of platelet formation in lung vasculature. The findings could inform new approaches to large scale generation of platelets.