EXPRESSION AND BIOACTIVITY OF RECOMBINANT CANINE ERYTHROPOIETIN

Objective-To produce recombinant canine erythropoietin (rcEPO) and com pare its biological activity with that of recombinant human EPO (rhEPO ). Animals-C57BL/6J mice. Procedure-The gene encoding cEPO was isolate d from a genomic library and subcloned into an eucaryotic expression v ector. Production of rcEPO was achieved by stable transfection of the expression construct into Chinese hamster ovary cells. Biological acti vity was evaluated in vitro by analyzing the mitogenic activity of rcE PO on murine erythroid progenitor cells. in vivo bioactivity was asses sed in mice by measuring the ability of rcEPO to increase blood reticu locyte counts. Results-Size and glycosylation of rcEPO expressed in Ch inese hamster ovary cells were similar to values for commercial rhEPO. Canine and human EPO stimulated proliferation of murine erythroid pro genitor cells in vitro and murine reticulocytosis in vivo in a dose-de pendent manner. Conclusions-Comparable biological activity was observe d for rcEPO and rhEPO in the 2 murine-based assay systems studied. By avoiding interspecies variation in protein structure and the resulting potential for immunogenicity, rcEPO should represent a better option than rhEPO for treatment of dogs with erythropoietin-dependent anemia. Clinical Relevance-Therapeutic use of rhEPO in companion animals is l imited by its immunogenicity and the resulting potential to induce pur e red cell aplasia. Development and availability of species-specific E PO preparations should avoid this problem.