The incomparable platelet: holy alveoli!

Platelets are indispensable for alveolar development in neonatal mice

Previous studies suggest that platelets are involved in fetal and adult lung development, but their role in postnatal lung development especially after premature birth is elusive. There is an urgent need to scrutinize this topic because the incidence of bronchopulmonary dysplasia (BPD), a chronic lung disease after premature birth, remains high. We have previously shown impaired platelet biogenesis in infants and rats with BPD. In this study, we investigated the role of anti-CD41 antibody-induced platelet depletion during normal postnatal lung development and thrombopoietin (TPO)-induced platelet biogenesis in mice with experimental BPD. We demonstrate that platelet deficient mice develop a BPD-like phenotype, characterized by enlarged alveoli and vascular remodeling of the small pulmonary arteries, resulting in pulmonary arterial hypertension (PAH)-induced right ventricular hypertrophy (RVH). Vascular remodeling was potentially caused by endothelial dysfunction demonstrated by elevated von Willebrand factor (vWF) concentration in plasma and reduced vWF staining in lung tissue with platelet depletion. Furthermore, TPO-induced platelet biogenesis in mice with experimental BPD improved alveolar simplification and ameliorated vascular remodeling. These findings demonstrate that platelets are indispensable for normal postnatal lung development and attenuation of BPD, probably by maintaining endothelial function.

Learning the Ropes of Platelet Count Regulation: Inherited Thrombocytopenias

Inherited thrombocytopenias (IT) are a group of hereditary disorders characterized by a reduced platelet count sometimes associated with abnormal platelet function, which can lead to bleeding but also to syndromic manifestations and predispositions to other disorders. Currently at least 41 disorders caused by mutations in 42 different genes have been described. The pathogenic mechanisms of many forms of IT have been identified as well as the gene variants implicated in megakaryocyte maturation or platelet formation and clearance, while for several of them the pathogenic mechanism is still unknown. A range of therapeutic approaches are now available to improve survival and quality of life of patients with IT; it is thus important to recognize an IT and establish a precise diagnosis. ITs may be difficult to diagnose and an initial accurate clinical evaluation is mandatory. A combination of clinical and traditional laboratory approaches together with advanced sequencing techniques provide the highest rate of diagnostic success. Despite advancement in the diagnosis of IT, around 50% of patients still do not receive a diagnosis, therefore further research in the field of ITs is warranted to further improve patient care.