Evaluation of saline, RPMI and DMEM/F12 for storage of split-thickness skin grafts

• We tested storage conditions for excess split-thickness skin.
• Histologically, no differences were observed between conditions.
• Storage time can be extended by using RPMI instead of normal saline.
• Storage of skin in RPMI resulted in higher viability, based on activity.

Skin grafting is standard of care for severe burn and trauma patients. Graft sites are often accompanied with more pain than the burn sites. To minimize graft site areas, excess skin remaining after harvesting, is stored in saline at 4 °C to be used for transplantation up to 1 week later. However, the optimal storage solution and maximum storage time are not known. We set out to determine the storage time after which stored skin is still viable. In addition, different storage solutions were tested.Split-thickness skin from 15 donors with a thickness of 0.3 mm was stored in normal saline, in medium, RPMI or DMEM/F12, allowing pairwise comparison. Biopsies were taken up to 3 weeks for histology and for skin viability assessment using an MTT based activity assay.Activity of the saline stored control decreased to 62% at day 7 and to 27% at day 14. Activity was retained at a higher level in RPMI and was 78% at day 7 and 70% at day 14. Results with DMEM/F12 showed a similar trend as the saline control. Based on activity, RPMI was found to be superior to DMEM/F12 (on days 3 and 10) and both saline and DMEM/F12 (on days 14 and 21). Capability to proliferate (BrdU incorporation) did not differ between media, up to 7 days. Histologically, the number of apoptotic cells increased in time but differences between media were not noted. Based on these results, RPMI would be an improvement over saline in retaining viability of skin grafts during storage, and possibly in improved take rate.