D. Koganti1, S. Tannouri1, C. Lotto1, E. Macarak2, J. Uitto2, J. Rosenbloom2 1Thomas Jefferson University,Dermatology/Surgery,Philadelphia, PA, USA 2Thomas Jefferson University,Dermatology,Philadelphia, PA, USA
Introduction: Burn wounds lead to severe disability due to contractures from abnormal healing. The mechanical properties of burns may be a consequence of aberrant scarring. We propose a protocol using a murine model for the mechanical testing of burn wounds. We then investigate the effects of topical therapies on burns using this model.
Methods: C57BL/6 mice underwent deep thermal injury by a heated brass plate on their dorsum. Burned and unburned skin was harvested at nine days, two weeks, and five weeks post-burn injury. We created a reproducible, standardized protocol using a custom 3-D stamp and tensometer to determine the mechanical properties of the skin. The effects of topical treatments (povidine-iodine, mupirocin, silver sulphadiazine) on the unburned and burned skin were then investigated.
Results: Tensile strength of burned skin was less than unburned skin at nine days (0.86 N/m2 vs. 3.21 N/m2, Student’s t- test, p=0.008), two weeks (0.31 N/m2 vs. 3.26 N/m2, p=0.004), and five weeks (0.69 N/m2 vs. 4.44 N/m2, p= 0.000006). At two weeks, burns treated with povidine-iodine (0.31 N/m2 vs 0.12 N/m2, p=0.03) and mupirocin (0.31 N/m2 vs. 0.10 N/m2, p=0.02) had less tensile strength than untreated burns. At five weeks, silver sulphadiazine weakened the burn vs. burned untreated skin (0.32 N/m2 vs 0.69 N/m2, p=0.01). Also, at five weeks, unburned skin with any of the agents (povidine-iodine: 2.03 N/m2 vs 4.44 N/m2, p=0.0002; mupirocin: 1.56 N/m2 vs 4.44 N/m2, p=0.0001; silver sulphadiazine: 1.50 N/m2 vs 4.44 N/m2, p=0.00009) was found to be weaker than unburned, untreated skin.
Conclusion: The tensile strength of a burn is decreased compared to unburned skin in a murine model, reflecting that the process of wound healing after burns causes weaker regenerated skin. Some commonly used topical therapies seem to lead to weaker healed skin than untreated burns. These agents also decrease the tensile strength of unburned skin and warrant further investigation. Using this protocol, tensile strength may be used as a parameter to evaluate the effect of therapies on healing of burn wounds.