BMP and Hedgehog regulate distinct AGM hematopoietic stem cells ex vivo

Hematopoietic stem cells (HSC), the self-renewing cells of the adult blood differentiation hierarchy, are generated during embryonic stages. The first HSCs are produced in the aorta-gonad-mesonephros (AGM) region of the embryo through endothelial to a hematopoietic transition. BMP4 and Hedgehog affect their production and expansion, but it is unknown whether they act to affect the same HSCs. In this study using the BRE GFP reporter mouse strain that identifies BMP/Smad-activated cells, we find that the AGM harbors two types of adult-repopulating HSCs upon explant culture: One type is BMP-activated and the other is a non-BMP-activated HSC type that is indirectly controlled by Hedgehog signaling through the VEGF pathway. Transcriptomic analyses demonstrate that the two HSC types express distinct but overlapping genetic programs. These results revealing the bifurcation in HSC types at early embryonic stages in the AGM explant model suggest that their development is dependent upon the signaling molecules in the microenvironment

STENOSIS: Long-term single versus dual antiplatelet therapy in patients with ischaemic stroke due to intracranial atherosclerotic disease – a randomised trial

Rationale Intracranial atherosclerotic disease (ICAD) is a pathological process that causes progressive stenosis and cerebral hypoperfusion, leading to stroke occurrence and recurrence around the world. The exact duration of dual antiplatelet therapy (DAPT) for ICAD is unclear in view of long-term risk of bleeding complications.Aim The current study aims to study the efficacy and safety of long-term DAPT (up to 12 months) in patients with ICAD.Sample size Using 80% power and an alpha error of 5 %, presuming a 10%–15% drop-out rate, a total of 2200 patients will be recruited for the study.Methodology This is a prospective, randomised, double-blind, placebo controlled trial.Study outcomes The primary outcomes include recurrent ischaemic stroke (IS) or transient ischaemic attack and any intracranial haemorrhage (ICH), major or minor systemic bleeding at the end of 12 months. Secondary outcomes include composite of any stroke, myocardial infarction or death at the end of 12 months. The safety outcomes include any ICH, major or minor bleeding as defined using GUSTO (Global Use of Streptokinase and tPA for occluded Coronary Arteries) classification at the end of 12 months and 1 month after completion of the drug treatment phase.Discussion The study will provide level I evidence on the duration of DAPT among patients with IS due to ICAD of more than or equal to 50%