A comparison of high-dose recombinant erythropoietin treatment regimens in brain-injured neonatal rats.

Recombinant human erythropoietin (rEpo) is neuroprotective in neonatal models of hypoxic-ischemic brain injury. However, the optimal rEpo dose, dosing interval, and number of doses for reducing brain injury are still undetermined. We compared the neuroprotective efficacy of several subcutaneous rEpo treatment regimens. Seven-day-old rats underwent unilateral carotid ligation plus 90 min 8% hypoxia. Treatment began immediately after injury. Treatment regimens examined included 1, 3, or 7 daily subcutaneous injections of either 0 (vehicle), 2,500, 5,000, or 30,000 U/kg rEpo. Gross brain injury, neuronal apoptosis (TUNEL), and gliosis (glial fibrillary acidic protein) were assessed at 48 h or 1 wk post injury. Immunoreactive cells and brain injury were quantified for statistical comparison to vehicle controls. rEpo treatment reduced brain injury, apoptosis, and gliosis, in a dose-dependent U-shaped manner at both 48 h and 1 wk. Neither one injection of 2,500, seven injections of 5,000, or three injections of 30,000 U/kg rEpo were protective. Three doses of 5,000 and one dose of 30,000 U/kg rEpo were most protective at both time intervals. rEpo provides dose-dependent neuroprotection. Of the regimens tested, three doses of 5,000 U/kg was optimal because it provided maximal benefit with limited total exposure.