M.F. Smiechowski, T.P. Flinn
Guild BioSciences,
United States
Keywords: burn wound treatment, enzymatic debridement, individual-care, buddy-care
Summary:
One of the primary advantages of enzymatic debridement is that it can be applied to burn wounds by non-surgical practitioners. This allows medics or other field personnel to initiate care at the point of injury, outside of a surgical theater. Currently available enzyme-based debridement products are limited by temperature-restricted storage requirements and have restrictions on co-dosing with antimicrobials. Overcoming these limitations will reduce the amount of time an individual is in a hypermetabolic state, decrease the risk for sepsis and mortality, and improve overall patient outcomes. This study investigated an enzyme immobilization process, ImmobiZyme™, that enables increased enzyme stability, improved resistance to proteolytic action, and an increased active half-life in complex environments. Immobilized enzyme samples were evaluated for long term storage stability, resistance to autolysis, performance against artificial wound eschar (AWE) membranes, cross-compatibility with antimicrobials, diffusion rates through healthy skin, effects on dermal cells (in vitro), and functionality in a lotion-form. Long term stability for the commercially available enzyme debridement products requires environmental control, the products cannot be stored above room temperature. For storage stability testing samples were held in an oven at 50 °C for up to 52 weeks. 2 of the 6 candidate formulations retained more than half their activity under these conditions, while 3 candidates retained more than 50% of their activity for more than 30 weeks. Resistance to autolytic deactivation was evaluated by comparing solutions of enzyme in buffer at wound relevant pH. Under each test condition the immobilized enzymes retained more activity over time than the non-immobilized enzymes. The immobilized enzymes demonstrated their ability to degrade skin proteins through tests with AWE, which provided a direct way to compare the different immobilization formulations against each other and against enzymes in their natural form. The results of these tests demonstrated the improved performance of the immobilized enzymes based on greater digestion of the AWE. Antimicrobial compatibility was evaluated by individually mixing immobilized enzyme candidates with 3 common antimicrobials, Neosporin, silver sulfadiazine, or cerium nitrate for several hours. The results from this testing showed that immobilized enzymes had better cross-compatibility will all three antimicrobials than untreated enzymes. Testing against skin-like polymer membranes showed that immobilized enzymes do not have the same capacity as natural enzymes to diffuse through and react against healthy tissues. Similarly, comparisons of the effect on the in vitro growth and survival of keratinocytes and fibroblasts validated that these cells are not negatively impacted by the presence of immobilized enzymes. The final tests involved incorporating the immobilized materials into a basic lotion and evaluating their performance against Santyl, a current enzyme debridement product, both in terms of capacity to digest AWEs and for elevated storage. Several basic lotion formulations were evaluated, and in each case the immobilized enzymes performed equivalently to the commercial product with respect to digesting AWEs and demonstrated improved heat-stability.