Objectives: Storage of autologous split-thickness skin grafts (STSG) is a standard method with acceptable results. Numerous different nutritional media are used. The arbitrarily maximum storage time is considered to be approximately 4 weeks. It is well known that there is a successive deterioration of viability and thus graft take with storage time paralleled by a transition from viable grafts to more of a biological dressing. The aim of this study is to explore an optimal storage medium yielding the highest number of viable cells at the time of re-transplantation. In the first step in this project we examined different nutritional fluids used for banking of autologous STSGs. 
Methods: Ten nutritional fluids used in vitro, clinically, or based on theoretical reasons. Cultured human keratinocytes from healthy donors were diluted to 1*106 cells/mL in various nutritional fluids and stored at 4-7° C for up to 30 days. Sampling was done at day 1, 4, 8, 14, 21, and 30 in storage. Evaluation included cell count, viability, visual check for cell aggregate and ability to resolve.
Results: The procedure was repeated four times. The summarized data at day 30 showed 2 nutritional fluids with 10% or more viable cells (McCoy´s 5A, RPMI 1640), 3 nutritional fluids with 5-9% viable cells, and 5 nutritional fluids with less than 5% viable cells.
Discussion: Over all there were, as anticipated, quite few viable cells after 30 days of storage in all nutritional fluids. For all medias a rapid decline in cell number was seen during day 1-8 and subsequently the reduction was reduced, wherefore days of storage is a central parameter. The aim of this project is to prolong the time viable STSG can be stored and maintain take rate. The project will continue with further studies on different storage media using keratinocytes and human STSG.

Optimization of storage conditions when banking autologous split-thickness skin grafts