Electrospun PLGA-Propolis Scaffolds Regulate Collagen Architecture in Burn Wounds

Wound (especially burn) healing, is a complex process involving cells e.g., leukocytes, macrophages, keratinocytes, fibroblasts, endothelial cells and platelets. Additionally, glycosaminoglycans, proteoglycans and collagen participate in the remodeling of the extracellular matrix (ECM). It is well-known that collagen, especially type I and III, are products of fibroblasts. These cells proliferate in the final phase wound healing. The various stages of skin regeneration, i.e., processes such as hemostasis, inflammation, cells' growth, differentiation and migration, can be accelerated by certain natural, biologically active, factors. The aim of this study was to evaluate the effect of a propolis-incorporated nonwoven on collagen organization and tissue architecture in a porcine burn model. Propolis, a bee-product rich in numerous diverse phenolic compounds, has been used since ancient times for the treatment of skin diseases and repairing various types of wounds. The research material consisted of tissue sections taken from burn wound beds inflicted in domestic pigs. The samples of skin sections were evaluated using routine light microscopy. Also, ultrastructural studies have been performed with scanning electron microscopy and atomic force microscopy. Nonwovens were made by electrospinning of a poly(lactide-co-glycolide) 85:15 copolymer (PLGA) without active compound as well as containing 5 wt% and 10 wt% of propolis. Electrospining solutions were dissolved in 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP). In the burn wound bed, propolis-incorporated dressings were associated with improved epithelial and dermal tissue organization and with an increased presence of organized collagen bundles (without direct assessment of collagen subtypes). These observations suggest that propolis incorporation is associated with improved collagen organization and tissue architecture at the histological level. The enhanced collagen deposition and organization observed in wounds treated with propolis-containing nonwovens indicate improved extracellular matrix remodeling and structural tissue organization in burned skin.