Cerebral edema is a potentially life-threatening illness, but knowledge of its underlying mechanisms is limited. Here we report that hypobaric hypoxia induces rat cerebral edema and neuronal apoptosis and increases the expression of corticotrophin releasing factor (CRF), CRF receptor type 1 (CRFR1), aquaporin-4 (AQP4), and endothelin-1 (ET-1) in the cortex. These effects, except for the increased expression of CRF itself, could all be blocked by pretreatment with an antagonist of the CRF receptor CRFR1. We also show that, in cultured primary astrocytes: (i) both CRFR1 and AQP4 are expressed; (ii) exogenous CRF, acting through CRFR1, triggers signaling of cAMP/PKA, intracellular Ca 2+, and PKCe; and (iii) the up-regulated cAMP/PKA signaling contributes to the phosphorylation and expression of AQP4 to enhance water influx into astrocytes and produces an up-regulation of ET-1 expression. Finally, using CHO cells transfected with CRFR1+ and AQP4 + , we show that transfected CRFR1+ contributes to edema via transfected AQP4 + . In conclusion, hypoxia triggers cortical release of CRF, which acts on CRFR1 to trigger signaling of cAMP/PKA in cortical astrocytes, leading to activation of AQP4 and cerebral edema.water permeability | high altitude | acute mountain sickness A pproximately 140 million people around the world live at altitudes of >2,500 m, including >8 million who live on the Qinghai-Tibet plateau of China at an average elevation of >4,000 m. Living at these altitudes requires physiological adaptations to compensate for the lower partial pressure of oxygen (1). In travelers who ascend to altitudes too high or too quickly (2-4) or in people with fatigue and infection or psychological stress (3, 4), hypoxia can induce acute mountain sickness (AMS) that can develop into high-altitude cerebral edema (HACE), a serious and often fatal condition (2-6). Today's ability to travel rapidly to high altitudes means that, every year, millions of people are exposed to the risk of AMS and HACE (7).In human volunteers exposed for 32 h to hypobaric hypoxia (corresponding to 4,572 m altitude), brain volume increases by 2.77% (8), whereas normobaric hypoxia (12% O 2 , corresponding to a simulated altitude of 4,500 m) for 16 h produces 50% AMS, headache, a mild increase in brain volume, and cytotoxic cerebral edema (9). A recent study reported that seven of nine male students exposed to isobaric hypoxia (inhaled room air enriched with N 2 for 6 h to obtain arterial saturation values of 75-80%) developed AMS; the mean apparent diffusion coefficient (ADC) increased by 2.12% in these subjects, indicating mild extracellular (vasogenic) cerebral edema. The ADC changes were negatively correlated with AMS scores, suggesting that severe AMS is associated with intracellular (cytotoxic) cerebral edema in addition to vasogenic edema (10).In parallel with the increasing brain water content, hypoxia acutely activates the hypothalamic-pituitary-adrenal axis in rats (11-13), increasing corticotropin-releasing factor (CRF) and endothelin-1 (ET-1)...

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Blastocyst complementation by pluripotent stem cell (PSC) injection is believed to be the most promising method to generate xenogeneic organs. However, ethical issues prevent the study of human chimeras in the late embryonic stage of development. Primate embryonic stem cells (ESCs), which have similar pluripotency to human ESCs, are a good model for studying interspecies chimerism and organ generation. However, whether primate ESCs can be used in xenogenous grafts remains unclear. In this study, we evaluated the chimeric ability of cynomolgus monkey (Macaca fascicularis) ESCs (cmESCs) in pigs, which are excellent hosts because of their many similarities to humans. We report an optimized culture medium that enhanced the anti-apoptotic ability of cmESCs and improved the development of chimeric embryos, in which domesticated cmESCs (D-ESCs) injected into pig blastocysts differentiated into cells of all three germ layers. In addition, we obtained two neonatal interspecies chimeras, in which we observed tissue-specific D-ESC differentiation. Taken together, the results demonstrate the capability of D-ESCs to integrate and differentiate into functional cells in a porcine model, with a chimeric ratio of 0.001–0.0001 in different neonate tissues. We believe this work will facilitate future developments in xenogeneic organogenesis, bringing us one step closer to producing tissue-specific functional cells and organs in a large animal model through interspecies blastocyst complementation.