Biocompatibility of pegylated fibrinogen and its effect on healing of full-thickness skin defects: A preliminary study in rats

Introduction: A synthetic polymer polyethylene glycol (PEG), was conjugated to fibrinogen as a threedimensional and biodegradable skin wound dressing matrix. This PEG-fibrinogen (PEG-fib) was tested in vivo in a skin wound time course study for its biocompatibility and biodegradation, after being delivered into the wound by injection and polymerized in situ by photo-activation. Materials and methods: The nature of the inflammatory response to the implanted material in acute, 8 mm diameter, full-thickness skin lesions in rats was histologically evaluated at 7 days (n=6) and 14 days (n=6). Six wounds per time point were left untreated as controls. Results: After 14 days, wounds of both groups were healed by up to 78% contraction and 22% epithelialization. Immune cells such as foreign body giant cells, macrophages, plasma cells and lymphocytes were seen in the PEGfib treated wounds at both time points, however in low numbers and similar to controls. The amount of immune cells dropped between day 7 and 14. Remnants of the gel were found at day 7 in two of the PEG-fib treated wounds, no PEG-fib were found after 14 days in any of the wounds. There was no difference in epithelialization between the two treatments at both time points. Discussion: The histological evaluation showed good biocompatibility of the PEG-fib, such that a foreign body reaction to the implant could be ruled out. The amount of immune cells was in accordance to a normal reaction to an implanted resorbable biomaterial. Conclusion: The PEG-fib hydrogel is fully biocompatible as a skin wound dressing. It provides initial moisture to the wound bed and is gradually resorbed and replaced by structured skin tissue. An attractive future perspective would be to prepopulate the PEG-fib hydrogel with cells (e.g. fibroblasts), or load it with growth factors or other soluble mediators to further promote healing of complicated skin wounds.