Figure 4.

SDF-1 reverses the neoangiogenesis defects in Mmp9^−/− and Thpo^−/− mice in a dose-dependent manner. (a) Hindlimb ischemia after femoral artery ligation was performed in Mpl^−/−, Thpo^−/− or wild-type mice. Plasma levels of SDF-1 were measured at indicated time points by ELISA. Plasma SDF-1 levels were persistently higher (3.2-fold at 48 h) in wild-type mice as compared to Mpl^−/− or Thpo^−/− mice during the first 72 h after femoral artery ligation (n = 6 per group, *P < 0.05). (b) The number of circulating CXCR4⁺VEGFR1⁺ cells in wild-type mice was 5.5-fold and 5-fold higher than that of Mpl^−/− mice 3 and 8 d after femoral artery ligation, respectively (n = 4 per group, *P < 0.05). (c) Administration of AdSDF-1 (low dose, 10⁸ p.f.u. intravenously) to Thpo^−/− mice after femoral artery ligation restored perfusion in the ischemic hindlimb by twofold as compared to the AdNull-treated controls. A higher dose (5 × 10⁸ p.f.u. intravenously) improved ischemic perfusion by 2.8-fold compared to AdNull-treated controls (n = 4 per group, *P < 0.05). (d) There was increased vessel density (CD31⁺ vessels/gastrocnemius or adductor muscle fiber, n = 4 per group) and less muscle necrosis in SDF-1–treated Thpo^−/− mice compared to AdNull-treated controls (n = 4 per group, data represent average from five separate high-power fields (HPFs)). Original magnification, ×400. (e) AdSDF-1 injection (low dose, 10⁸ p.f.u. intravenously) in Mmp9^−/− mice restored perfusion in the ischemic hindlimb by 1.95-fold compared to AdNull-treated controls. A higher dose (5 × 10⁸ p.f.u. intravenously) improved ischemic perfusion further by 2.5-fold compared to AdNull-treated controls (n = 4 per group, *P < 0.05).