Expansion and delivery of human fibroblasts on micronized acellular dermal matrix for skin regeneration

In order to obtain an abundant supply of autologous dermal fibroblasts for the manufacture of engineered autologous dermal substitutes, we fabricated the micronized acellular dermal matrix (MADM) microcarriers and expanded human fibroblasts on them. This novel approach eliminated the need for the repeated trypsinizations that may disrupt cell-extracellular matrix interactions and impair cell viability. This cell expansion protocol simultaneously formed an engineered particulate dermal substitute (EPDS) avoiding cell reseeded on the scaffolds process. We further tested its feasibility and effectiveness in athymic murine subcutaneous injection and full-thickness cutaneous wound model. Our results showed that MADM microcarriers retained the ultrastructure of the acellular dermal matrix, had good biocompatibility, and supported human fibroblast expansion either as a direct culture substrate or through culturing cells in conditioned medium prepared from them. In the animal study, EPDS formed a thick layer of tissue below the subcutaneous muscle tissue at 3 weeks following EPDS injection into subcutaneous tissue. In full-thickness cutaneous wound, the degree of wound healing with EPDS implantation was better than that without EPDS although healing rates were not significantly different between wounds implanted with or without EPDS. This demonstrates the potential utility of MADM not only as a cell culture substrate to expand fibroblasts but also as a cell transplantation vehicle for skin regeneration, with several advantages over current expansion-transplantation protocols for skin regeneration. In addition, EPDS may be used for cosmetic or reconstructive soft tissue augmentation in a minimally invasive fashion.