IntroductionWe previously showed that erythropoietin (EPO) attenuates the morphological signs of spinal cord ischemia/reperfusion (I/R) injury in swine [1] without, however, improving neurological function. The clinical use of EPO has been cautioned most recently due to serious safety concerns arising from an increased mortality in acute stroke patients treated with EPO and simultaneously receiving systemic thrombolysis [2]. Carbamylated EPO (cEPO) is an EPO derivative without erythropoietic activity and devoid of the EPO side eff ects, but with apparently well maintained cytoprotective qualities [3]. We therefore tested the hypothesis whether cEPO may be equally effi cient as EPO in reducing morphological as well as functional aortic occlusion-induced spinal cord I/R injury. Methods In a randomized and blinded trial pigs received either vehicle (control, n = 9), EPO or cEPO, respectively (n = 9 each; 5,000 IU/kg over 30 minutes before and during the fi rst 4 hours of reperfusion). Animals underwent 30 minutes of thoracic aortic balloon occlusion with catheters placed immediately downstream of the A. subclavia and upstream of the aortic trifurcation. Spinal cord function was assessed by motor evoked potentials (MEP as percentage of the amplitude before aortic occlusion) and lower limb refl exes (assessed as the subjective strength of response) for a period of 10 hours after reperfusion. Tissue damage was evaluated using Nissl staining. Results Both EPO-treated and cEPO-treated animals presented with attenuated spinal cord injury in the Nissl staining (median (quartile) percentage of damaged neurons in the thoracic segments: control 27 (25,44), cEPO 8 (4,10), and EPO 5 (5,7), P <0.001 vs control group; in the lumbar segments: control 26 (19,32), cEPO 7 (5,13), EPO 8 (5,10), P <0.001 vs control group). However, while only cEPO treatment was associated with recovery of the MEP amplitude to pre-occlusion values when compared with the control group (P <0.05), lower limb refl ex response was comparably restored stronger in both treatment groups (P <0.05 vs control). Conclusions In a clinically relevant porcine model mimicking aortic crossclamping during vascular surgery repair of thoracic aortic aneurysm, cEPO protected spinal cord function and integrity as eff ective as EPO when applied at equipotent doses. Acknowledgements Supported by the Deutsche Forschungs gemeinschaft (SCHE 899/2-2). References Introduction Unfolded protein response (UPR)-mediated apoptosis plays a pivotal role in ischemia-reperfusion injury. Sodium 4-phenylbutyrate (PBA) has been reported to act as a chemical chaperone inhibiting UPR-mediated apoptosis triggered by ischemia in various organs other than the heart. Therefore we investigated whether PBA reduces UPR-mediated apoptosis and protects against myocardial ischemia-reperfusion injury in mice. Methods C57BL/6 mice were subjected to 30 minutes LAD ischemia followed by reperfusion. PBA (100 mg/kg) or PBS (control) was administrated intraperitoneally just before ischemia. Apoptosis, infarct ...
