BBB-targeting, protein-based nanomedicines for drug and nucleic acid delivery to the CNS.
Erythropoietin (EPO) is a potential new treatment for acute stroke. However, EPO does not cross the blood-brain barrier (BBB). EPO has been re-engineered as an IgG-EPO fusion protein, where EPO is fused to the heavy chain of a chimeric monoclonal antibody (MAb) against the mouse transferrin receptor (TfR), which is designated the cTfRMAb-EPO fusion protein. The re-engineered EPO is able to penetrate the BBB following intravenous (IV) administration owing to transport on the BBB TfR. In the present study, the neuroprotective properties of EPO alone and the cTfRMAb-EPO fusion protein following IV injection were investigated in a permanent middle cerebral artery occlusion (MCAO) model in the adult mouse. Following MCAO, mice were treated IV with low (1000 U/kg) and high (10,000 U/kg) doses of recombinant EPO, or with low (0.05 mg/kg) or high (1.0 mg/kg) doses of the cTfRMAb-EPO fusion protein. Hemispheric stroke volume and neural deficit scores were quantitated 24h after MCAO. There was no reduction in stroke volume or neural deficit following the IV administration of either dose of EPO or the low dose of cTfRMAb-EPO fusion protein. However, after treatment with the 1.0 mg/kg dose of the cTfRMAb-EPO fusion protein, the hemispheric stroke volume was reduced 81% and the neural deficit was reduced 78%. These studies demonstrate high degrees of neuroprotection in stroke with EPO when the neurotrophin is re-engineered as an IgG-EPO fusion protein to enable transport across the BBB following IV administration.