Abstract Sa604: Trapezoidal wave chest compression plays neuroprotective role by alleviating neuronal ferroptosis in mice after CA-CPR-ROSC via cerebral microvascular endothelial cell derived extracellular microvesicles

Background: Nowadays, cardiopulmonary resuscitation (CPR) instruments used worldwide utilize sinusoidal wave for chest compression. The instrument independently invented by our research group performs chest compression through trapezoidal wave, which can achieve higher carotid blood flow and cerebral microcirculation blood perfusion, and ultimately reduce neuron death and blood brain barrier (BBB) injury after CPR, ultimately, improve the prognosis. However, the underlying mechanisms are complicated and remain largely unknown. Therefore, this study investigated the specific mechanisms so as to make contribution to the popularization of TWCC. Methods: Cardiac arrest-CPR-return of spontaneous circulation (CA-CPR-ROSC) mouse models attained by TWCC/sinusoidal wave chest compression (SWCC) and the oxygen-glucose deprivation reoxygenation (OGD/R) model of primary neurons treated by brain tissue derived sEV TWCC /sEV SWCC were established, and the level of neuronal ferroptosis was detected. AAV-BR1-CD63-GFP was injected via lateral cerebral ventricle to lable brain microvascular endothelial cells-derived small extracellular vesicles (BMEC-sEV), and AAV9-BR1- Rab27a-shRNA was used to suppress the generation of BMEC-sEV. The effects of ferroptosis on ROSC rate and neurological prognosis in mice were confirmed by ferroptosis activators/inhibitors. Results: It was confirmed that, compared with SWCC/ OGDR+sEV TWCC group, the ferroptosis level of neurons in TWCC/OGDR+sEV TWCC group was significantly higher, which was mainly manifested by the changes of mitochondrial morphology, ferroptosis related proteins and lipid peroxidation levels. Immunofluorescence showed that BMEC-sEV labeled by green fluorescent protein (GFP) could be taken in by neurons. Compared with SWCC+AAV-BR1-CD63-Rab27a-NC group, the ferroptosis level of neurons in SWCC+ AAV-BR1-CD63-RAB27A-shRNA group was significantly reduced, indicating that the neuroprotective effect of TWCC was closely related to BMEC-sEV. In addition, the ROSC rate, neurological function score and 7-day survival rate were higher in SWCC group treated with Fer-1 and Lip-1 than SWCC group, while, mice given RSL3 and Erastin were completely opposite to that. Conclusion: In general, our results demonstrate that TWCC exacerbates brain damage after CPR by facilitating neuronal ferroptosis via BMEC-sEV. Key words: cardiac arrest; neurons; ferroptosis; small extracellular vesicles