Abstract:
Recombinant human erythropoietin (rHuEPO) is currently used for renal anemia treatment. Recently, rHuEPO has been shown to provide pleiotrophic tissue protection in various pathologic conditions. The benefits of rHuEPO beyond anemia treatment are limited since it increases red blood cell mass. Carbamylated erythropoietin (CEPO) is the first rHuEPO derivative that lacks erythropoietic activity, but retains tissue protection properties. Since carbamylation targets lysine residues on rHuEPo, we hypothesized that targeted-lysine modifications of rHuEPO may result in a novel non-erythropoietic erythropoietin. rHuEPO was subjected to various targeted-lysine modifications. In vitro cytoprotection and apoptosis were evaluated using P19 and HEK293 cells. In vivo erythropoiesis was performed by administrating these derivatives into animals for two weeks. Renoprotection was tested on ischemia/reperfusion (I/R) model. We here synthesized a novel derivative, a glutaraldehyde erythropoietin (GEPO). This derivative abolishes in vivo erythropoiesis. In vitro experiments showed that GEPO had the cytoprotective activities in both P19 and HEK293 cells In vivo experiments also showed that GEPO ameliorated kidney damage due to I/R injury in both functional and histological aspects. Biochemical characterization showed that GEPO was more electrostatically negative than rHuEPO. Immunoprecipitation revealed that GEPO bound to the βCR/EPOR heterotrimeric receptor and ameliorated cellular apoptosis via the activation of Bcl-2.
