FIGURE 1

(a–d) Representative photomicrographs showing apoptotic changes in HUVECs subjected to A/R. Only occasional nontransfected cells show positive TUNEL staining (a) and immunoreactivity for activated caspase-3 (c). In contrast, the majority of cells transfected with HIF-1 siRNA duplexes demonstrate positive TUNEL staining (b) and immunoreactivity for activated caspase-3 associated with morphologic evidence of apoptotic damage (d). (e–h) Representative photomicrographs demonstrating knockdown of HIF-1 mRNA and protein expression by HIF-1 siRNA duplexes in HUVECs subjected to A/R. Many nontransfected cells demonstrate strong HIF-1 mRNA expression by in situ hybridization (e), whereas HIF-1 mRNA is barely detectable in cells transfected with siRNA duplexes (f). Strong immunoperoxidase reactivity for HIF-1 is observed in most nontransfected cells, (g) but only an occasional cell transfected with siRNA shows HIF-1 immunoreactivity (h).