Dermal regeneration in full‐thickness wounds in Yucatan miniature pigs using a biodegradable copolymer

The aim of this study was to assess the performance of a biodegradable dermal substrate in deep dermal skin defects. The substrate consisted of a synthetic biodegradable matrix called Polyactive, which is an elastomeric poly (ether)/poly (ester) block copolymer. This matrix was manufactured either as a porous substrate, with gradually changing pore size (BISKIN‐M), or as a bilayer consisting of a porous underlayer with a fully dense surface layer (BISKIN). Cell‐free matrices and matrices seeded with autologous or allogeneic porcine fibroblasts were applied to full‐thickness skin wounds in Yucatan miniature pigs. Biopsies were taken at different time intervals up to 24‐months post‐transplantation. Although all BISKIN substrates showed little or no adherence to the wound bed, the adherence of the BISKIN‐M substrates to the underlying wound was achieved within minutes after application. Therefore, only BISKIN‐M Polyactive substrates were further evaluated. Wound contraction was inhibited by both cell‐free and fibroblast‐populated substrates. All substrates showed extensive neovascular and fibrous tissue ingrowth within 2‐weeks post‐transplantation. Furthermore, during this time period, matrix degradation was observed, starting with the fragmentation of the polymers into particles, which were phagocytized by macrophages. These processes occurred actively up to 3 months and ceased thereafter. Cell‐free substrates degraded faster, and also, the collagen deposition was lower as compared with cell‐seeded substrates. The tissue surrounding the remnants of the Polyactive substrates after 24‐months post‐transplantation consisted of a mature connective tissue. The newly formed collagen had the same distribution pattern as observed in normal native dermis. We conclude therefore that treatment of full‐thickness skin defects with fibroblast‐populated BISKIN‐M Polyactive substrates leads to satisfactory dermal regeneration.