Fig 1. Cell viability of keratinocytes in the prepared cultured epidermis.

Fresh, cultured epidermis without cryopreservation and used within 48 h; cryopreserved, cryopreserved at -80 °C for 7 days with DMSO; frozen, stored at -80 °C for 7 days without DMSO; and freeze and thaw (FT), the freeze-thaw cycle was repeated five times to destroy cell membranes.