The ischemic core is believed to lose cells through necrosis initiated at the onset of embolic stroke. Hence, the vast majority of stroke research has only focused on arresting the spread of neuronal death by rescuing cells in the penumbra which die more slowly through apoptosis. Our lab has successfully limited infarct progression and boosted behavioral recovery by treating the middle cerebral artery occluded (MCAO) rat model of stroke with i.v. administered human umbilical cord blood cells (HUCBC). Recently, we found that the majority of animals treated with HUCBC 48 hrs following MCAO fully recovered, (Newcomb et al., SFN, 2004), challenging the notion that cells in the core are necrotic and beyond therapeutic intervention. In the present study we reproduced these findings and extended our description of cell death and inflammation after MCAO and HUCBC transplantation. Sixty-three male Sprague-Dawley rats were randomly distributed into three groups (Sham, MCAO only and MCAO + HUCBC). Loss of cerebral bl...