Apelin gene transfer promotes development of larger vessels in the hind limb ischemia model. (A) Gross appearance of foot pad from sham-operated mice (sham) or ischemic mice injected with genes as indicated 14 days after resection of the femoral artery. (B) Representative laser Doppler images of a mouse hind limb 14 days after surgery and gene transfer as indicated. Red represents greater flow; and blue, less flow. (C) Quantification of laser Doppler-monitored blood flow measurements. Data are from ratio of ischemic right leg versus nonischemic left leg mice injected with genes as indicated (n > 10). *P < .01. (D) CD31 staining of quadriceps muscle from mice 14 days after surgery and gene transfer as indicated. Muscle from sham-operated (sham) mice was used for comparison. (E-F) Quantitative evaluation of the vessel number (E) and the percentage of enlarged blood vessels more than 30 μm relative to the total number of blood vessels (F) in mice 14 days after surgery and gene transfer as indicated. *P < .01.