Highly efficient platelet generation in lung vasculature reproduced by microfluidics
Platelets, small hemostatic blood cells, are derived from megakaryocytes. Both bone marrow and lung are principal sites of thrombopoiesis although underlying mechanisms remain unclear. Outside the body, however, our ability to generate large number of functional platelets is poor. Here we show that perfusion of megakaryocytes ex vivo through the mouse lung vasculature generates substantial platelet numbers, up to 3000 per megakaryocyte. Despite their large size, megakaryocytes are able repeatedly to passage through the lung vasculature, leading to enucleation and subsequent platelet generation intravascularly. Using ex vivo lung and an in vitro microfluidic chamber we determine how oxygenation, ventilation, healthy pulmonary endothelium and the microvascular structure support thrombopoiesis. We also show a critical role for the actin regulator Tropomyosin 4 in the final steps of platelet formation in lung vasculature. This work reveals the mechanisms of thrombopoiesis in lung vasculature and informs approaches to large-scale generation of platelets.
Acknowledgements: We gratefully acknowledge the Wolfson Bioimaging Facility for their support and assistance in this work. We are also grateful to Professor Jack Mellor, University of Bristol, for the use of the tissue slicer machine. This work was supported by a Wellcome Trust Investigator Award to A.W.P. (219472/Z/19/Z) and C.G. (219472/A/19/Z) and grants from the British Heart Foundation (RG/15/16/31758 to A.W.P., SP/F/21/150023 to A.W.P., C.G. & I.H. and PG/16/102/32647 to A.W.P. and E.O.A.). B.N. was funded by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, project number 374031971- TRR 240/project A01).
British Heart Foundation (BHF) (RG/15/16/31758, PG/16/102/32647, PG/21/10760, SP/F/21/150023, PG/16/102/32647, SP/F/21/150023, SP/F/21/150023)
Deutsche Forschungsgemeinschaft (German Research Foundation) (374031971 - TRR 240/project A01)
Wellcome Trust (Wellcome) (219472/A/19/Z)