Topically applied liposome encapsulated superoxide dismutase reduces postburn wound size and edema formation

The overproduction of biochemical mediators, and activation of leukocytes and endothelial cells, generated in thermally injured tissue, gives rise to both local and distant effects. The formation of short-lived, highly reactive metabolites, such as oxygen free radicals, increases with increasing tissue ischemia, and causes further cell damage. Human recombinant Cu/Zn-superoxide dismutase (rh-Cu/Zn-SOD), an enzyme which captures these radicals, may have a beneficial effect on the postburn inflammation processes. In this study, the influence of rh-Cu/Zn-SOD application to thermally injured tissue of rabbit backskin was examined. Three different delivery strategies were compared, pure or liposomally encapsulated enzyme, or intralesionally injected rh-Cu/Zn-SOD. For control, one animal group was treated with plain gel and another group was kept untreated. At 24 h following trauma a statistically significant difference in lesion sizes between the enzyme treated and control groups was observed. After 72 h tissue swelling had diminished significantly more in the rh-Cu/Zn-SOD treated groups as compared to the control animals. The best results were achieved by spreading liposomes encapsulating the enzyme onto the wounds. Our results suggest that local treatment of burn wounds with enzymatic radical scavengers such as rh-Cu/Zn-SOD has a beneficial effect on the extent of the postburn damage.