Tissue-Engineered Skin Regenerative Units for Epidermal Keratinocytes Expansion and Wound Healing.

Chronic wounds have become an increasing medical and economic problem of aging societies because they are difficult to manage. Tissue engineering provides new perspectives for the clinically applicable skin substitutes. Epidermal keratinocytes play an important role in wound epithelization and construction of tissue-engineered skin substitutes. How to obtain a large number of autologous epidermal keratinocytes in a short time is the main problem that limits the application of tissue-engineered skin and epidermal cell membranes. Developing an appropriate method for reproducing the biological potential of cell-cell interactions and simulating the three-dimensional structure between cells has great significance for epidermal keratinocytes expansion and full-thickness skin regeneration. In this article, we propose the concept of tissue-engineered skin regeneration units (TESRUs) as the smallest unit with complete full-thickness skin regeneration ability. First, autologous dermal fibroblasts are cultured in biodegradable macroporous microcarriers to provide the mesenchyme support. Second, autologous epidermal keratinocytes and autologous melanocytes are incubated with the fibroblasts-loaded microcarriers and expand in vitro. Incorporating the above co-culture method into the macroporous microcarriers is reasonable for maintaining cell-cell interactions in spatial and temporal context and providing a suitable growth niche for epidermal keratinocytes. Moreover, TESRUs are composed of fibroblasts, keratinocytes, and melanocytes and have complete full-thickness skin regeneration ability. We suggest that TESRUs could be a promising strategy to repair full-thickness skin defects for clinical applications if the hypothesis proves to be practical.