In Vivo Neuroprotective and Pharmacological Studies of Plant-Produced Asialo-erythropoietin

Asialo-rhuEPO, a non-hematopoietic recombinant human erythropoietin (EPO) derivative lacking sialic acid, has been reported to display broad tissue-protective effects against damage triggered by ischemia/reperfusion (I/R), hypoxia or cytotoxic agents in the brain, the heart, the kidneys and the liver. However, attempts to translate its protective effects into clinical practice are hampered by the unavailability of a suitable expression system and its costly and limited production from expensive mammalian cell-made EPO (rhuEPOM) by enzymatic desialylation.

It is known that plants can synthesize complex N-glycans similar to mammals but lack sialylating capacity. We hypothesized that the plant-based expression system lacking sialylating capacity while possessing the ability to synthesize complex N-glycans can be utilized to produce asialo-rhuEPO. Our previous studies have demonstrated that co-expression of human EPO and ß1,4-galactosyltransferase (GalT) genes in tobacco plants could produce soluble asialo-rhuEPO. Purified plant-produced asialo-rhuEPO (asialo-rhuEPOP) from transgenic tobacco leaves was found to have a better cytoprotective effect than rhuEPOM in protecting neuronal-like mouse neuroblastoma cells, murine HL-1 cardiomyocytes and pancreatic ß-cells from staurosporine-induced cell death. These milestone studies have set the stage for the current proposed research activities.

The proposed research activities would help develop asialo-rhuEPOP as a drug for the treatment of stroke patients. Furthermore, these studies will lay a solid foundation for us to compete for non-SCORE support for studying tissue-protective effects and action mechanisms of asialo-rhuEPOP in various animal models of tissue injury and clinical trials. The proposed project will also provide training opportunities for our students, who will be engaged in hypothesis-driven research to prepare them with scientific competency and laboratory experience either to work in the pharmaceutical/biotechnology industries or to pursue advanced studies.