Abstract 16479: Remote Ischemic Preconditioning: Do Exosomes Play a Requisite Role in Evoking Cardioprotection?

Remote ischemic preconditioning (RIPC) is the phenomenon whereby brief episodes of ischemia-reperfusion applied in distant tissues or organs render the heart resistant to a subsequent sustained ischemic insult. The hallmark of RIPC is inter-organ communication, with recent evidence suggesting that exosomes may serve as the vector for the transport of protective factor(s) from the site of the distant trigger to the cardiomyocytes. To test this hypothesis, rats underwent a standard RIPC stimulus: i.e., 4 5-min episodes of bilateral femoral artery occlusion. Serum (~3 mL per rat) was harvested immediately after RIPC; 1 mL was stored at -80°C, and 2 mL was processed for exosome isolation by prolonged ultracentrifugation (12 hours at 300,000xg). Aliquots of the pellet and supernatant were probed (by immunoblotting) for expression of exosome markers including HSP60 and flotillin. Most importantly, the cardioprotective efficacy of: 1) RIPC serum, 2) the pellet, reconstituted in buffer, 3) supernatant-bottom laye...