Abstract A058: Selective mild hypothermia enhances astrocyte-to-neuron mitochondrial transfer via cAMP signaling in ischemic stroke

Background: Therapeutic hypothermia has demonstrated robust neuroprotective effects in experimental models of ischemic stroke. However, clinical translation has been hindered by delays in cooling initiation. To address this limitation, we investigated whether initiating selective mild hypothermia during the ischemic phase could improve outcomes and examined the underlying mechanisms. Astrocyte-to-neuron mitochondrial transfer has recently emerged as a critical endogenous neuroprotective process following cerebral ischemia and may be enhanced by early hypothermia. Methods: Selective brain cooling was initiated 30 minutes after stroke onset to mimic early mild hypothermia and maintained for 2 hours in adult mice, subjected to transient middle cerebral artery occlusion (MCAO). Astrocytic mitochondria were fluorescently labeled to track intercellular transfer. Single-cell RNA sequencing was performed on ischemic brain tissue. Cyclic AMP (cAMP) signaling was modulated using pharmacological agonists and antagonists. Results: Early mild hypothermia significantly reduced infarct volume and improved neurological outcomes when induced during cerebra ischemia. It enhanced astrocyte-to-neuron mitochondrial transfer in the peri-infarct cortex. Single-cell analysis revealed upregulation of cAMP-related pathways in astrocytes following early mild hypothermia. Activating cAMP signaling mimicked the protective effects of hypothermia, while its inhibition partially attenuated mitochondrial transfer and functional recovery because of early mild hypothermia after stroke. Conclusions: Early mild hypothermia promotes neuroprotection by enhancing astrocytic mitochondrial transfer through a cAMP-dependent mechanism. Targeting this glia-mediated pathway may improve therapeutic strategies for ischemic stroke.