Evaluating silk fibroin-based biomaterials using human epidermis equivalent models

Abstract

　　In this study, to develop silk fibroin (SF)-based sponges used in the field of skin esthetics and skin tissue engineering, the influence of the SF solution and the SF sponge on gene expressions in three-dimensional (3-D) reconstructed human keratinocytes with or without melanocytes as a skin equivalent model was evaluated by quantitative reverse transcription-polymerase chain reaction (RT-PCR) experiments. Commercially available collagen (Col) solution and sponge were used for comparison. In the 3-D skin model made from keratinocytes, no marked changes in the expressions of genes related to differentiations and barrier functions of epidermis were observed between both solutions and sponges of SF and Col. RT-PCR experiments using the 3-D skin model with both keratinocytes and melanocytes revealed that gene expression levels of melanogenesis-related factors on the 3-D skin models stimulated with the SF sponge were slightly higher than that on the Col sponge. Measurements of pigment areas in the 3-D skin models with melanocytes indicated that almost identical areas of black melanin were detected in the 3-D skin models stimulated with medium, SF sponge, and Col sponge. This study indicates that SF-based materials are biologically inert to human skin epidermis, similar to collagen-based materials.