G. Garg1,2, J. S. Vazquez1,2, J. H. Chen1,2, B. C. Carney2,4, M. V. Cruz1,2, T. E. Travis1,2,3, L. T. Moffatt2,4, J. W. Shupp1,2,3,4 1MedStar Washington Hospital Center,The Burn Center,Washington, DC, USA 2MedStar Health Research Institute,Firefighters’ Burn And Surgical Research Laboratory,Washington, DC, USA 3Georgetown University School of Medicine,Department Of Surgery,Washington, DC, USA 4Georgetown University School of Medicine,Department Of Biochemistry,Washington, DC, USA
Introduction: Burn progression, in which initially uninjured skin adjacent to deep partial or full thickness burns (the zones of stasis) becomes necrotic, occurs over the first 24-72 hours after injury. Many factors likely contribute to burn wound progression, such as inflammation, oxidative stress, and disruption of cell cycle regulation. Media used to grow mesenchymal stem cells (MSCs) is rich in cytokines and cell mediators that promote healing and can therefore potentially impact multiple pathways. The present study aimed to use MSC-conditioned media in an easily applied topical gel to treat the zone of stasis in an attempt to prevent burn progression, salvaging healthy tissue.
Methods: A rat comb burn model was used to generate serial burns with viable interspaces. Burn areas including interspaces were treated with two applications of conditioned media (n=6) or vehicle (n=6). The applications were at 30 minutes and 24 hours after injury. Digital photographs and Laser Doppler Imaging (LDI), of burns and interspaces were obtained daily for seven days from the burn area on the left flank. Percentages of interspace conversion were calculated from digital photos using ImageJ software, and perfusion units obtained from regions of interest in LDI analysis. Biopsies were obtained from the burn and interspaces on the right side and then paraffin-embedded, sectioned, and stained with hematoxylin and eosin (H&E). Immunofluorescent staining was used to quantify caspase-3 expression in cells in the papillary dermis.
Results: The percentage of converted interspace area was significantly reduced in the treated rats compared to control each post-burn day (1.25% vs. 27.2% on day 1, 16.2% vs. 47.3% on day 2; p < 0.05). Interspace perfusion was significantly increased in the treated rats compared to sham rats (p<0.05). H&E stained sections demonstrated that the treatment group had increased epidermal thickness, though not statistically significant. Further, Immunofluorescent staining demonstrated an 88.4% decrease in caspase-3 expression in the treated rats compared to sham rats (p<0.05).
Conclusion: MSC-derived conditioned media is a novel topical therapy to prevent burn progression. This may be mediated by an inhibition of apoptosis. Further study is warranted to evaluate the molecular pathways associated with this positive effect in order to identify a potential therapeutic target. This therapy may serve to reduce the areas of necrotic tissue requiring excision and grafting, therefore minimizing the associated complications of surgery including bleeding, infection, and length of stay.