T+RB-PTS produces a greater fibrin content in the ensuing clots than RB-PTS. (A) A similar size of infarction was induced by RB (14.4 ± 2.50 mm³; n = 7) or Thrombin-RB (T+RB) photothrombosis (14.1 ± 2.84 mm³; n = 8), whereas photoactivation after systemic intravenous application of thrombin failed to induce cerebral infarct (n = 6). (B-C) Histological analysis of MCA showed a higher content of fibrin (green colored) in blood clots after T+RB photothrombosis than RB photothrombosis, as shown by co-immunostaining of fibrin(ogen)/CD41 (platelets; B), and fibrin/TER119 (RBCs; C) (n = 3 for each group). The transverse sections of MCA (bottom rows) were costained with isolection-B4 (IB4) to outline the vascular lumen. Note the occlusion of the whole vessel, similar to the FeCl₃-induced stroke model.³⁰  Scale bars, 50 μm. (D) Immunoblot analysis indicated greater fibrin deposits in the ipsilateral hemisphere at 2 hours after the T+RB than the RB photothrombosis stroke model. Two representative samples are shown here, as well as the quantification of 3 mice for each model (P = .027 by unpaired Student t test). Cont, contralateral hemisphere; Ipsi, ipsilateral hemisphere; UN, uninjured sham mice.