The efficacy and sterilisation of human decellularised dermal allografts with combinations of cupric ions and hydrogen peroxide.

Decellularised tissue allografts have been used in reconstructive surgical applications and transplantation for many years. Some of the current methods of sterilisation have a detrimental effect on the tissue graft structure and function. The anti-microbial activity of cupric ions and hydrogen peroxide (H2O2) are well known however their combined application is not currently utilised as a decontamination agent in the tissue banking world sector. The aim of this study was to determine the combined concentrations of copper chloride (CuCl2) and H2O2 that have the optimal bactericidal and sporicidal activity on decellularised (dCELL) human dermis. The first part of this study established the decimal reduction time (D-value) of CuCl2 (0.1 mg/L and 1 mg/L) together with H2O2 (0.01, 0.1, 0.5 and 1%) for Staphylococcus epidermidis, Escherichia coli and Bacillus subtilis spores. The second part of this study identified the most effective CuCl2 and H2O2 concentration that decontaminated dCELL human dermis inoculated with these pathogens. Of all the concentrations tested, 0.1 mg/L CuCl2 in combination with 1% H2O2 had the shortest D-value; S. epidermidis D = 3.15 min, E. coli D = 2.62 min and B. subtilis spores D = 18.05 min. However when adsorbed onto dCELL dermis, S. epidermidis and E. coli were more susceptible to 1 mg/L CuCl2 together with 0.5% H2O2. These studies show promise of CuCl2-H2O2 formulations as potential sterilants for decellularised dermal allografts.

Development of a terminally sterilised decellularised dermis.

Many of the decellularised dermis products on the market at present are aspectically produced. NHS Blood and Transplant Tissue Services have developed a method of producing a dCELL human dermis which has been terminally sterilised by gamma irradiation. The terminally sterilised decellularised dermis was compared with cellular tissue and examined for histology, residual DNA content, biomechanical and biochemical properties, in vitro cytotoxicity and in vivo implantation in a mouse model. No alterations in morphology as viewed by light microscopy were observed and DNA removal was 99%. There were no significant changes in ultimate tensile stress or evidence for collagen denaturation or cytotoxicity. The in vivo studies did not indicate any adverse tissue reactions in the mouse model and demonstrated incorporation of dCELL human dermis into the host. Decellularisation, followed by terminal sterilisation with gamma irradiation, is an appropriate method to produce a human dermis allograft material suitable for transplantation.