Ischemia reperfusion injury associated with apoptosis and inflammation plays crucial roles in renal transplantation. Erythropoietin provides renoprotection, but its effects and mechanisms on kidney preservation are not fully defined. Porcine kidneys, subjected to 10 min warm ischemia, underwent 16 h cold storage followed by 2 h normothermic hemoperfusion with or without 5000 units/L erythropoietin. Apoptotic cells were increased in tubular lumens and interstitial areas by normothermic perfusion alone, but decreased in tubular areas by additional erythropoietin. Myeloperoxidase+ cells, free cells and cell debris in tubular lumens were gradually increased by cold storage, normothermic perfusion and erythropoietin in normothermic perfusion. Accordingly, caspase-3 activity as well as its active proteins was increased by normothermic perfusion and furthered by erythropoietin. In contrast, macrophage L1 protein positive cells in tubulointerstitial areas, cytokine interleukin (IL)-1β activation, tubular dilation and vacuolation were raised by normothermic perfusion, but all alleviated by erythropoietin, with higher urine output. The migration of myeloperoxidase+ cells with apoptotic features and apoptotic cells with polymorphous nuclei from tubulointerstitial areas into tubular lumens was widely displayed in the kidneys, especially those preserved by erythropoietin in normothermic perfusion. HSP70 protein was enhanced by normothermic perfusion regardless of erythropoietin. In addition, erythropoietin induced a dose-dependent increase in caspase-3 precursor in porcine proximal tubular cells (LLC-PK1) and also stimulated caspase-3 cleavage in cisplatin-treated cells. In conclusion, erythropoietin promotes inflammatory cell apoptosis, drives inflammatory and apoptotic cells into tubular lumens, eventually leads to inflammation clearance, renoprotection and tissue remodelling through caspase-3 and IL-1β in isolated haemoperfused kidneys.
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