Burns are common injuries that can result in significant scarring, leading to poor function and disfigurement. Unlike mechanical injuries, burns often progress both in depth and in size over the first few days after injury, possibly due to inflammation and oxidative stress. A major gap in the field of burns is the lack of an effective therapy that reduces burn injury progression. Because stem cells have been shown to improve healing in several injury models, the authors hypothesized that species-specific mesenchymal stem cells (MSCs) would reduce injury progression in a rat comb-burn model.Using a brass comb preheated to 100?C, the authors created four rectangular burns, separated by three unburned interspaces on both sides of the backs of male Sprague-Dawley rats. The interspaces represented the ischemic zones surrounding the central necrotic core. In an attempt to reduce burn injury progression, 20 rats were randomized to tail vein injections of 1 mL of rat-specific MSCs, 10(6) cells/mL (n = 10), or normal saline (n = 10), 60 minutes after injury.While the authors were unable to identify any quantum dot (Q-dot)-labeled MSCs in the injured skin, at 7 days the mean percentage of the unburned interspaces that became necrotic in the MSC group was significantly less than in the control group (80% vs. 100%, p <0.0001).Intravenous injection of rat MSCs reduced burn injury progression in a rat comb-burn model.? 2013 by the Society for Academic Emergency Medicine.