The viability change of pigskin in vitro

Abstract Background It is widely recognised that take of grafts is strongly influenced by tissue viability. Although porcine skin is currently the most widely used xenograft, the viability change of pigskin in vitro has not been extensively studied. The purpose of this study was to assess the change of the viability of Bama miniature pigskin after harvest and cryopreservation, and to set up a guideline for pigskin preservation and storage that would allow the skin to retain the highest viability after treatment and still be used in the clinical applications. Methods Harvested pigskin grafts were divided into five groups: normal saline medium/4 °C (group 1), Dulbecco's minimum essential medium (DMEM)/4 °C (group 2), normal saline medium/25 °C (group 3), DMEM/25 °C (group 4) and cryopreserved (group 5). In our experiment, the viability was investigated by 3-(4,5)-dimethylthiazol-2,5-diphenyl tetrasolium bromide (MTT) salt assay. We also evaluated the transplantation performance of preserved skin in different conditions by using a rat recipient model, in which primary take was evaluated by gross observation and predetermined histological criteria after 7 days. Results Skin stored at 4 °C showed a very slow viability decrease with time. The sample showed a viability decrease of about 70% after 3 days in normal saline and 4 days in DMEM medium. Nevertheless, skin stored in DMEM at 25 °C underwent a viability increase during the first 4 h and then decreased gradually to about 70% after 20 h, while the viability declined very quickly for skin grafts stored in normal saline medium at 25 °C, and maintained the same viability only within 6 h of preservation. On the other hand, cryopreserved skin has been shown to maintain a level of skin metabolism equal to 77% of the fresh sample when measured immediately after thawing, and the viability remained about 70% after 6 h at 25 °C and 2 days at 4 °C in DMEM. The graft performance of skin specimens with 70% viability of fresh skin stored in different conditions has not shown statistical significance compared with fresh pigskin. Conclusions Based on these results, we suggest that the conservation period of fresh pigskin should not exceed 72 or 96 h when stored in normal saline or DMEM at 4 °C, and should not exceed 6 or 18 h when stored in normal saline or DMEM at 25 °C. Cryopreserved pigskin should be stored in DMEM for a maximum period of 48 h at 4 °C and 6 h at 25 °C after thawing.