Peina Wang

Uncontrolled hemorrhage in trauma, surgical, organ-related, and endoscopic settings, particularly in patients receiving antiplatelet therapy, remains difficult to manage clinically. Here, we introduce a high phosphatidylserine (PS)–exposed procoagulant platelet (hPPL) derivative reprogrammed from isolated platelets via calcium ionophore A23187–induced apoptosis, enriched in surface PS and capable of driving rapid hemostasis. Retaining a protein profile akin to resting platelets, hPPLs robustly promoted platelet activation and aggregation in human- and rat-derived plasma and whole blood in vitro and demonstrated superior hemostatic efficacy compared with clinical thrombin and commercial hemostatic materials [microporous polysaccharide hemispheres (MPH) and FIBRILLAR] in murine liver injury and porcine gastric ulcer bleeding models, even under antiplatelet treatment. Mechanistically, hPPLs up-regulated prostaglandin E synthase (PTGES), thereby increasing prostaglandin E2 (PGE ₂ ) production and its receptor 3 (EP3)–mediated platelet activation, which reinforced PS-mediated clot formation. Our findings identified an apoptosis-driven PTGES-PGE ₂ -EP3 signaling axis that augmented PS-mediated coagulation in murine and porcine hemorrhage models and established the hPPL derivative as a topical hemostatic agent with translational potential for organ-related bleeding and distinct advantages in managing complex endoscopic hemorrhages under both physiological and coagulopathic conditions.

Liver sinusoidal endothelial cells (LSECs) are essential for maintaining liver function by actively sensing nutrients and producing angiocrine factors. LSECs also regulate systemic iron metabolism by secreting bone morphogenetic proteins (BMPs), which are key modulators of systemic iron homeostasis. However, the mechanism by which LSECs sense iron to regulate iron metabolism remains unclear. Here, we identify that the endothelial transcriptional factor forkhead box protein O1 (Foxo1) and its upstream protein kinase, mechanistic target of rapamycin complex 2 (mTORC2), as critical iron sensors. In response to iron, Foxo1 undergoes acute and dynamic nuclear translocation to activate the transcription of Bmp2 and Bmp6, thereby stimulating the synthesis of iron-regulatory hormone hepcidin in adjacent hepatocytes. Foxo1 directly binds evolutionally conserved Foxo binding sites within the Bmp2 and Bmp6 promoters to mediate this response. Mechanistically, iron triggers the lysosomal degradation of the mTORC2-specific component rapamycin-insensitive companion of mTOR (Rictor), enhancing Foxo1 activation. Endothelial-specific Foxo1 deletion reduces the expressions of hepatic Bmp2/6 and hepcidin, leading to systemic iron overload, whereas endothelial Rictor deletion increases the expressions of hepatic Bmp2/6 and hepcidin, producing an iron-deficient phenotype. Moreover, endothelial-targeted lipid nanoparticles expressing endothelial-specific and constitutively active Foxo1 alleviate iron overload in a murine model of hereditary hemochromatosis. Collectively, our study establishes the endothelial mTORC2-Foxo1 axis as an iron-responsive regulator of Bmp2 and Bmp6 expression and identifies it as a promising target for iron-related disorders.

Iron is important for life, and iron deficiency impairs development, but whether the iron level regulates neural differentiation remains elusive. In this study, with iron-regulatory proteins (IRPs) knockout embryonic stem cells (ESCs) that showed severe iron deficiency, we found that the Pax6- and Sox2-positive neuronal precursor cells and Tuj1 fibers in IRP1^−/−IRP2^−/− ESCs were significantly decreased after inducing neural differentiation. Consistently, in vivo study showed that the knockdown of IRP1 in IRP2^−/− fetal mice remarkably affected the differentiation of neuronal precursors and the migration of neurons. These findings suggest that low intracellular iron status significantly inhibits neurodifferentiation. When supplementing IRP1^−/−IRP2^−/− ESCs with iron, these ESCs could differentiate normally. Further investigations revealed that the underlying mechanism was associated with an increase in reactive oxygen species (ROS) production caused by the substantially low level of iron and the down-regulation of iron-sulfur cluster protein ISCU, which, in turn, affected the proliferation and differentiation of stem cells. Thus, the appropriate amount of iron is crucial for maintaining normal neural differentiation that is termed ferrodifferentiation.