ABSTRACT
Background and aims: Vaccination is one of the most important countermeasures in the ongoing COVID19-pandemic. Pharmacovigilance concerns, however, emerged after very rare, but potentially disastrous thrombotic complications following vaccination with ChAdOx1. The underlying pathology was described as platelet factor 4 antibody mediated vaccine-induced immune thrombotic thrombocytopenia (VITT). Mechanisms of immunothrombosis including the regulation of neutrophil extracellular traps (NETs) might be of crucial importance in VITT. Methods: In this study, we had the exceptional opportunity to investigate blood and thrombus samples of a patient who suffered severe ischaemic stroke due to VITT undergoing successful mechanical thrombectomy (MT) in comparison to 13 control stroke patients with similar clinical characteristics without VITT. Cerebral thrombi were stained for complement factors, NETs-markers, DNase and LL-37 and were histologically assessed. In blood samples before MT and 7 days later, cell-free DNA, myeloperoxidase-histone complexes, myeloperoxidase activity, DNase activity, LL-37 and inflammatory cytokines were determined. Results: We identified NETs-markers in thrombi of all patients. The thrombus of the VITT-patient, however, exclusively revealed complement factors and high amounts of NETs-degrading DNase and LL-37, which protects NETs from degradation. In accordance, ex vivo and in vitro studies also implied a disturbed regulation of NETs in VITT-samples. Moreover, we found markedly pronounced temporal changes of specific circulating cytokines in the VITT-case. Conclusions: The results of this study suggest a disturbed endogenous regulation of NETs in VITT involving a pro-inflammatory response and fulminant clinical course. Further studies are warranted to confirm our results and to provide deeper insights into the causative mechanisms.
ABSTRACT
Imaging intact human organs from the organ to the cellular scale in three dimensions is a goal of biomedical imaging. To meet this challenge, we developed hierarchical phase-contrast tomography (HiP-CT), an X-ray phase propagation technique using the European Synchrotron Radiation Facility (ESRF)'s Extremely Brilliant Source (EBS). The spatial coherence of the ESRF-EBS combined with our beamline equipment, sample preparation and scanning developments enabled us to perform non-destructive, three-dimensional (3D) scans with hierarchically increasing resolution at any location in whole human organs. We applied HiP-CT to image five intact human organ types: brain, lung, heart, kidney and spleen. HiP-CT provided a structural overview of each whole organ followed by multiple higher-resolution volumes of interest, capturing organotypic functional units and certain individual specialized cells within intact human organs. We demonstrate the potential applications of HiP-CT through quantification and morphometry of glomeruli in an intact human kidney and identification of regional changes in the tissue architecture in a lung from a deceased donor with coronavirus disease 2019 (COVID-19).