Effect of injected CD34⁺ cells on neointimal phenotype. CD34⁺ cells from WT mice were purified 2 days after wire injury, and incubated in vitro for 1 hour in either medium only (A) or with added thrombin (B) or PAR-1 and PAR-4 antagonists (C) before 7.5 × 10⁵ cells were injected back into a second WT mouse immediately following wire injury. Alternatively, CD34⁺ cells were purified from WT (D), α-TFPI–Tg (E), or α-Hir–Tg mice (F) and injected immediately into a second injured mouse. (A-D) 3-color immunohistologic analysis of frozen sections from day 28 after injury. Sections were stained with DAPI (blue). (E,F) 2-color immunohistologic analysis. All sections stained with anti–α-SMA (red) and anti-CD31, anti–E-selectin, and either anti-TF or antifusion protein (green) as indicated. Yellow indicates colocalization. Original images taken at ×100 magnification. Repeated twice.