Neuroprotection with or without erythropoiesis; sometimes less is more.

Erythropoietin (EPO) is a pleiotropic cytokine with a therapeutic potential that goes well beyond the treatment of anaemia. The study by Wang et al (2007b) examined the protective effects of EPO in a rat model of embolic stroke. The efficacy and haematological side effects of EPO were compared to those of a carbamylated EPO variant (CEPO). Treatment with EPO dose-dependently reduced infarct volume and improved long-term functional outcome. However, an increase in hematocrit was seen even for doses of EPO that did not offer neuroprotection. These data do not suggest the existence of a therapeutic window between effect and side effect for treatment with EPO. Treatment with CEPO was without haematological side effects.