Pigmentation of skin graft is improved by cryopreservation of human skin with trehalose.

Purpose: It is well-known that hyperpigmentation of a skin graft occurs more frequently in patients of color. The objective of this study was to investigate a modified protocol in which trehalose is combined with dimethyl sulfoxide (Me2SO) to improve the pigmentation of skin grafts.

Materials And Methods: Human skin samples were harvested from patients with breast cancer. Trehalose 0.5 mol/L combined with 10% v/v Me2SO was used as a cryoprotectant. Skin samples were divided into 3 groups: fresh (n = 10), cryopreserved with trehalose/Me2SO (n = 10), and cryopreserved Me2SO alone (n = 10). The viability of skin was evaluated using hematoxylin and eosin staining, Ki-67 immunostaining, and by transplantation to immunodeficient mice. After transplantation, grafts were photographed and harvested for analysis by histologic and ultrastructural observations and cytokeratin 5/6 immunostaining.

Results: After cryopreservation, trehalose/Me2SO-cryopreserved skin maintained well-preserved epidermal and dermal structures when evaluated using hematoxylin and eosin staining. In the fresh and trehalose/Me2SO groups, no differences in Ki-67 positive unit values (26.79 ± 1.55 vs 26.04 ± 1.15) were observed. When transplanted to immunodeficient mice, hyperpigmentation, melanocytes, and melanosomes were found in fresh skin. Skin cryopreserved with trehalose/Me2SO appeared to match harmoniously, cytokeratin 5/6 immunostaining showed that some trehalose/Me2SO-cryopreserved skin grafts were of human origin and the rest of mouse origin.

Conclusion: These results suggest that a combination of trehalose and Me2SO significantly increases the protective effect of skin tissues during cryopreservation. More importantly, this technique seems to prevent pigmentation of skin grafts.