Banking of non-viable skin allografts using high concentrations of glycerol or propylene glycol.

The aims of this study were to investigate the kinetics of the current glycerol banking method for the preservation of non-viable skin allografts; to improve it with respect to efficiency and microbial safety; and to investigate the possibility of using propylene glycol in place of glycerol to provide a more rapid process. Skin grafts were preserved in 98% v/v glycerol (GLY) according to the method used in the Sheffield Skin Bank. During the addition and removal processes, the amounts of GLY and water in the skin were determined using the Karl Fischer method and HPLC respectively. Propylene glycol (PG) was investigated as an alternative to glycerol with the object of shortening the process. To avoid the need for prolonged storage in glycerol to disinfect the tissue, and to improve the effectiveness of disinfection, exposure to peracetic acid (PAA) was included and its influence on the kinetics of the preservation process was evaluated. The histological and ultrastructural appearances of skin that had been banked by these methods was also investigated. It was found that the permeation of GLY in skin probably involves two processes: diffusion and binding; the rate of transport was attenuated as the GLY concentration in the skin increased. The current incubation time could be shortened, but an inconveniently prolonged washout process was required. The substitution of PG for GLY accelerated the whole process, particularly the removal process, making the method more convenient for the emergency use of skin grafts in the clinic. The penetration of PG also involved diffusion and binding, but there was no attenuation of transport as the concentration increased. The addition of PAA sterilisation did not alter the transport of GLY or PG. Structural integrity was also maintained with the new banking treatments. An improved banking method can now be proposed; it can be completed in only one working day and the risk of disease transmission is reduced.