a, Selective gene transfer to the heart by the tissue suction method. The heart was suctioned at −75 kPa. At 6 h after transfection, various tissues (the heart, left and right lungs, liver, spleen, and kidneys) were collected. Transgene expression in each organ was determined by luciferase assay and normalized to the expression of cardiac tissue. Open columns and open dots represent the mean and individual data, respectively (n = 3). ***p<0.001 compared with all other groups. b, Analysis of transgene-expressing cell types by immunostaining of endothelial cells and cardiac muscle cell markers. The pZsGreen1-N1 was transfected to the heart by the tissue suction method. The heart was suctioned at −75 kPa and then collected at 24 h after transfection. Finally, 10 μm-thick frozen sections were stained with anti-CD31 and α-sarcomeric actin antibodies and DAPI. The stained sections were observed by using CLSM. Magnification ×40. Blue: nucleus; yellow: ZsGreen1-N; cyan: α-sarcomeric actin-positive cardiac muscle cells; magenta: CD31-positive endothelial cells. Scale bars = 50 μm. White arrows indicate ZsGreen1-expressing cells.