Fig. 1: Surgical scheme and assessment of magnetic particle stroke.

a Surgical strategy for MCA stroke using magnetic particles: (1) Right common carotid artery surgically isolated and held by nylon thread; (2) Animal turned supine and scalp excised to remove right temporal muscle, exposing temporal bone; (3) Thinning of temporal bone to ~70 µm over MCA using burr drill; (4) Placement of magnet over thinned area; (5) Tail vein injection of 250 µl tMP in saline; (6) Accumulation of particles in distal branches of the MCA. b Laser Doppler flowmetry measuring relative cerebral blood flow (CBF) changes as perfusion units (PU) in the MCA territory before surgery, following carotid ligation (CL), tMP injection (MPS), 30 min occlusion, and reperfusion after the removal of both magnet and CL. Effect of particle size and composition on LDF (180 nm n = 4, 500 nm MP n = 9, 500 nm tMP n = 9; bar graphs show binned time points. Occlusion and reperfusion groups showing binned data points from final 10 min of recordings). One hundred eighty nanometer particles failed to provide sufficient decrease in CBF. Five-hundred-nanometer particles provided sufficient drop in CBF with immediate reperfusion upon magnet removal. Five-hundred-nanometer thrombin particles (tMP) provide desired sustained drop in CBF following magnet removal. One-way ANOVA with Tukey’s post-hoc test or Kruskal–Wallis test with Dunn’s post-hoc test as appropriate. Data are presented as mean values ± SEM. c LDF trace of 500 nm tMP with and without administration of bolus 10 mg/kg tPA modeling therapeutic reperfusion (500 nm tMPS alone n = 9; 500 nm tMP with tPA or saline, n = 5). Occlusion and reperfusion groups showing binned data points from final 10 min of recordings. One-way ANOVA with Tukey’s post-hoc test or Kruskal–Wallis test with Dunn’s post-hoc test as appropriate. Data are presented as mean values ± SEM. d, Cresyl Violet staining of 30 µm thick coronal brain sections collected at 300 µm intervals. Infarct outlined in yellow. Top panel is sham (magnet and carotid ligation surgery without particles). e Infarct volume at 48 h with and without 10 mg/kg tissue plasminogen activator (tPA). Unpaired two-sided t-test (n = 7/group). Data are presented as mean values ± SEM. Source data are provided as a Source Data file.