Human-Albumin Neuroprotection in Acute Ischemic Stroke: Marked Efficacy at Moderate Doses, with a Broad Therapeutic Window.
We have previously shown that high-dose human albumin (Alb) is markedly neuroprotective in focal and global cerebral ischemia and in traumatic brain injury. In this study, we examined the efficacy of moderate, clinically achievable Alb doses and defined the therapeutic window in focal cerebral ischemia. Sprague Dawley rats (n=62) were anesthetized with halothane/nitrous oxide and received 2-h middle cerebral artery occlusion (MCAo) by intraluminal suture. Neurological status was evaluated during occlusion (60 min) and daily for 3 days after MCAo. In the dose-response study, animals were given either 25% Alb in doses 0.63 or 1.25 g/kg , or 0.9% saline vehicle, i.v. immediately after suture removal (n=5 each). In the therapeutic window study, 1.25 g/kg Alb was administered at either 2 h, 3 h, 4 h, or 5 h after onset of stroke (i.e., 0 to 3 h after onset of reperfusion) (n=9–10 ea.). Three days after MCAo, brains were perfusion-fixed, and image-processing was used to compute infarct volumes and brain swelling. Both moderate Alb doses (0.63 and 1.25 g/kg) significantly improved the neurological score compared to vehicle rats at 24h, 48h and 72h; and markedly reduced cortical infarct volume (by 66±14% and 95±4%, respectively), striatal infarct volume (by 54±8% and 52±14%), and total infarct volume (by 58±5% and 67±9%, respectively). Brain edema was virtually eliminated by Alb treatment. In the therapeutic window study, even when treatment was initiated as late as 4 hours after onset of MCAo, 1.25 g/kg Alb led to significantly improved neurological score and highly significant reductions of infarct areas in cortex (68% reduction), subcortical regions (52% reduction), and total infarct (61% reduction). The striking efficacy and broad therapeutic window of moderate-dose Alb therapy in experimental focal ischemia strongly supports the feasibility of initiating early-phase clinical trials of this promising agent in patients with acute ischemic stroke. This work was supported by NIH Grant NS05820 (MDG) and by AHA Initial Investigator Award (LB).