Figure 4. Endothelial targeting of catalase encapsulated into anti-PECAM coated stealth polymer nanocarriers protects against oxidative stress.

Panel A: cell culture studies. Human endothelial cells were incubated with ¹²⁵I-catalase loaded IgG/PNC (black bars) or anti-PECAM/PNC (grey bars) for 1 hour, washed and treated with 5mM H₂O₂. The amount of catalase delivered was determined by iodine tracing. Cell death was measured by ⁵¹Cr-release after 5 hours (56.1±2.1% ⁵¹Cr was released from control cells treated with 5mM H₂O₂) and percent of protection was calculated. N=4. Panels B–E: animal studies. Anesthetized mice were injected with either anti-PECAM/PNC/catalase or catalase-free anti-PECAM/PNC and lungs were isolated from the animals 30 min later to test their capacity to decompose perfused H₂O₂ (see Methods). Anti-PECAM/PNC loaded with catalase suppressed both lipid peroxidation in the lung determined by TBARs level (B: N=4, M±SE) and DCF-fluorescence (C–E) induced by H₂O₂. Typical images of 2-photon fluorescent microscopy show DCF fluorescence in the vasculature in control lungs without and with H₂O₂ infusion (C and D, respectively), as well as in the lungs obtained from mice injected anti-PECAM/PNC/catalase and infused with H₂O₂ (E). Scale bar = 54μm. Asterisks denote statistical significance (*p<=0.5, **p<=0.01).