COURTESY OF MARK LOONEY, UCSF
E. Lefrançais et al., “The lung is a site of platelet biogenesis and a reservoir for haematopoietic progenitors,” Nature, 544:105-09, 2017.
Platelets form when megakaryocytes release bits of their specialized cytoplasm, a process long thought to occur primarily in the bone marrow. Mark Looney, a pulmonologist at the University of California, San Francisco, says human studies had reported that blood leaving the lungs contained fewer megakaryocytes and more platelets than blood entering it—suggesting the lungs were producing platelets. “But it’s never been visualized, it’s never been caught in the act.”
In a recent study, Looney and colleagues observed fluorescently labeled megakaryocytes in mice releasing platelets within the lung microvasculature—catching “the act” on video. The researchers estimated...