CHAPTER 5. A Novel Treatment for Giant Congenital Melanocytic Nevi Combining Inactivated Nevus Tissue by Pressurization and Cultured Epidermal Autograft

Giant congenital melanocytic nevi (GCMN) are intractable skin tumors associated with a risk of melanoma. Reconstructing such large, full-thickness skin defects after removing nevi using skin grafting is difficult. To overcome these issues, cultured epidermal autograft (CEA) was approved for the treatment of GCMN patients in 2016 in Japan. However, the take rate of CEA to wound beds lacking dermis is unsatisfactory. We started reconstructing the autologous dermis from the removed GCMN itself. Using high hydrostatic pressure (HHP), we prepared the dermal layer using the removed inactivated nevus tissue. Human skin and human nevus could be inactivated by HHP at 200 MPa without any detectable damage to the dermal structure or epidermal basement membrane. Cultured epidermis (CE) took to skin and nevus inactivated by HHP at 200 MPa without removing cellular remnants. One problem is the inflammation caused by the remaining cellar remnants, so we are evaluating the inflammation in an ongoing clinical trial. If the efficacy and safety of this strategy for retransplanting autologous tumor tissue as the autologous native matrix can be validated in a clinical trial, it could be widely applied to other tissues, such as bone, cartilage, nerve or vessels, that are usually discarded after tumor removal.