Poly-N-Acetyl Glucosamine Nanofibers

Abstract

In several fields of surgery, the treatment of complicated tissue defects is an unsolved clinical problem. In particular, the use of tissue scaffolds has been limited by poor revascularization and integration. In this study, we developed a polymer, poly-N-acetyl-glucosamine (sNAG), with bioactive properties that may be useful to overcome these limitations. To develop a scaffold-like membrane with bioactive properties and test the biologic effects in vitro and in vivo in diabetic wound healing. In vitro, cells-nanofibers interactions were tested by cell metabolism and migration assays. In vivo, full thickness wounds in diabetic mice (n = 15 per group) were treated either with sNAG scaffolds, with a cellulosic control material, or were left untreated. Wound healing kinetics, including wound reepithelialization and wound contraction as well as microscopic metrics such as tissue growth, cell proliferation (Ki67), angiogenesis (PECAM-1), cell migration (MAP-Kinase), and keratinocyte migration (p 63) were monitored over a period of 28 days. Messenger RNA levels related to migration (uPAR), angiogenesis (VEGF), inflammatory response (IL-1beta), and extracellular matrix remodeling (MMP3 and 9) were measured in wound tissues. sNAG fibers stimulated cell metabolism and the in vitro migratory activity of endothelial cells and fibroblasts. sNAG membranes profoundly accelerated wound closure mainly by reepithelialization and increased keratinocyte migration (7.5-fold), granulation tissue formation (2.8-fold), cell proliferation (4-fold), and vascularization (2.7-fold) compared with control wounds. Expression of markers of angiogenesis (VEGF), cell migration (uPAR) and ECM remodeling (MMP3, MMP9) were up-regulated in sNAG treated wounds compared with controls. The key mechanism of the bioactive membranes is the cell-nanofiber stimulatory interaction. Engineering of bioactive materials may represent the clinical solution for a number of complex tissue defects.