[Optimal conditions for the storage of split-thickness skin at 4C]

Split-thickness human skin must, out of necessity, be stored for days to years prior to usage as a burn wound covering. This study was designed to utilized three different parameters of tissue viability in order to determine optimum conditions for skin survival at 4 degrees C for various periods of time in RPMI-1640 media. Viability was determined by 1) trypan blue dye exclusion of trypsinized basal cells (TBC), 2) 14C-leucine incorporation into TBC, and 3) in vitro skin explant growth. Electron microscopy was also done on selected samples.

Split-thickness (0.2-0.3 mm) cadaveric skin (obtained within 24 hours of death) was divided into 6 tubes containing RPMI-1640 (pH 7.3) supplemented with 10% Nu-serum and 25 mM Hepes. The ratio of skin to media varied from 0.2 to 8.0 cm2/ml. The samples were then stored at 4 degrees C for up to 4 weeks with weekly changes of media.

Following 7 days storage, optimal viability (as determined by averaging the viabilities obtained from the above assays) was found for samples stored at a ratio of 2 cm2/ml (90.3 +/- 4.2%). Samples stored at ratios between 1.0 and 6.0 cm2/ml all maintained acceptable viabilities (i.e., greater than 78%), while samples at either 0.2 or 8.0 cm2/ml were both about 57% viable. EM demonstrated edema in all samples. The viability of skin stored for 4 weeks at 2-4 cm2/ml decreased dramatically after 2 weeks.

RPMI-1640 is an excellent medium for the storage of split-thickness skin at 4 degrees C, 2-4 cm2/ml, for up to 7 days. Because of the high viability retained in skin stored under these conditions, further long term storage in liquid nitrogen should provide good quality tissue for transplantation.