139 Topical Exogenous Nutrient and Saline Supplementation to Improve Skin Graft Survival: From Lab to Operating Room

Abstract

Introduction Skin grafting of poorly vascularized wound beds, (e.g. exposed fascia, tendon, or bone) is often a multi-stage procedure, resulting in persistent open wounds and long-term complications such as scarring and contracture. Single-stage skin replacement could mitigate these downsides. Here we present the addition of topical nutrients and negative-pressure wound therapy (NPWT) + saline instill to improve graft take, and a case report of treatment of a non-healing wound in a single-stage procedure. Methods Ex vivo, STSGs (12/1000ths in) were harvested from swine (Sus scrofa domestica) post-euthanasia and transferred into wells with distilled water, PBS, Tyrode’s Buffer, high (4.5g/L) and low (2g/L) glucose DMEM, EpiLife, or William’s E (WE) media for 7 days, followed by performance of biochemical analyses and immunohistochemistry. In vivo, 20 full-thickness 5cm-diameter excisional wounds on the dorsum of two anesthetized swine were treated with dermal substitutes (DS, 0.4mm, 0.8mm, 1.2mm, or 1.6mm thickness), STSG, and NPWT with or without intermittent saline instill (3x daily, 300mL, 15-minute soak). Re-epithelialization was assessed at day 7 and 14. Lastly, a chronic 800cm2 left knee wound was treated with NPWT + instill (every 3.5 hours, 80mL, 10-minute soak, 3-day duration) over a 12/1000ths inch STSG. Results DMEM with high glucose (DMEM-HG) and WE produced the most lactic acid and enzymatic carbonate. Lactate dehydrogenase activity was lowest with WE. DMEM-HG had the highest glucose consumption but the most unconsumed glucose, with WE resulting in the next highest amount. Immunohistochemistry showed DMEM-HG or WE had the most dividing and least dying cells. In the porcine model, DS of 0.8mm, 1.2mm, and 1.6mm thicknesses inhibited graft take significantly (p< 0.01, p=0.02, p< 0.01, respectively) for all NPWT alone wounds. Addition of saline instill showed significant improvement in graft take (p=0.03) for 0.8mm DS wounds. 1.2mm and 1.6mm DS wounds continued to show significantly decreased graft take (p=0.03 and p=0.02, respectively). All 0.4mm DS wounds performed similar to control. Clinically, following NPWT removal on post-op day 3, almost complete STSG take was observed without exudate, pus, or malodor within the wound bed. Conclusions While additional studies are ongoing to determine the optimal nutrient supplementation, WE performed the best overall thus far. In vivo, 0.8mm DS created a successful model of a poorly vascularized wound bed, as NPWT + instill overcame this thickness. The novel use of NPWT + instill treatment over STSG clinically shows promise to improve graft take in the future.