Overexpression of catalase in myeloid cells causes impaired postischemic neovascularization.

Objective: Myeloid lineage cells (MLCs) such as macrophages are known to play a key role in postischemic neovascularization. However, the role of MLC-derived reactive oxygen species in this process and their specific chemical identity remain unknown.

Methods And Results: Transgenic mice with MLC-specific overexpression of catalase (Tg(Cat-MLC) mice) were created on a C57BL/6 background.

Angiopoietin-2 stimulates blood flow recovery after femoral artery occlusion by inducing inflammation and arteriogenesis.

Objective: Recently, we have shown that shear stress regulates the angiogenic potential of endothelial cells in vitro by an Angiopoietin-2 (Ang2)-dependent mechanism; however its pathophysiological significance in vivo was not clear. We hypothesized that Ang2 plays an important role in blood flow recovery after arterial occlusion in vivo by regulating angiogenesis and arteriogenesis.

Methods And Results: C57Bl/6J mice underwent femoral artery ligation and were injected with a specific Ang2 inhibitor, L1-10, or vehicle for 10 days.

In vivo imaging of hydrogen peroxide with chemiluminescent nanoparticles.

The overproduction of hydrogen peroxide is implicated in the development of numerous diseases and there is currently great interest in developing contrast agents that can image hydrogen peroxide in vivo. In this report, we demonstrate that nanoparticles formulated from peroxalate esters and fluorescent dyes can image hydrogen peroxide in vivo with high specificity and sensitivity. The peroxalate nanoparticles image hydrogen peroxide by undergoing a three-component chemiluminescent reaction between hydrogen peroxide, peroxalate esters and fluorescent dyes.