Mitigation of hypertrophic scar contraction via anti-TNFalpha conjugated hyaluronic acid gels and poly(l-lactide-co-epsilon-caprolactone) electrospun scaffolds

Abstract

Event Abstract Back to Event Mitigation of hypertrophic scar contraction via anti-TNFalpha conjugated hyaluronic acid gels and poly(l-lactide-co-epsilon-caprolactone) electrospun scaffolds Elizabeth Lorden1, Emily E. Friedrich2, Mohamed M. Ibrahim3, Latif Bashirov3, Howard Levinson3, 4, Newell R. Washburn2, 5, 6 and Kam W. Leong1, 7 1 Duke University, Biomedical Engineering, United States 2 Carnegie Mellon University, Biomedical Engineering, United States 3 Duke University Medical Center, Plastic and Reconstructive Surgery, United States 4 Duke University Medical Center, Pathology, United States 5 Carnegie Mellon University, Chemistry, United States 6 University of Pittsburgh, McGowan Institute for Regenerative Medicine, United States 7 Columbia University, Biomedical Engineering, United States Introduction: Hypertrophic scar (HSc) occurs in 40-70% of patients treated for third degree burn injuries. Clinical observation suggests that the likelihood of HSc is increased in injuries with a prolonged immune response. Early mediation of the inflammatory phase of the immune response during wound healing is likely a key factor in rescuing thermally injured tissue from progressive wound remodeling and contraction. During the acute inflammation phase of wound healing, hyaluronic acid (HA) becomes highly prevalent in the wound bed. Conjugation of an anti-TNFα monoclonal antibody to high molecular weight HA has been shown to lead to decreased inflammatory response in an incisional wound model[1]. We explore the impact of (HA+anti-TNFα) hydrogels on HSc contraction using an immune-competent murine model[2]. We compare the efficacy of HA+anti-TNFα gel treatment with our previously described poly(l-lactide-co-ε-caprolactone) (PLCL) scaffold[3]. The long-term goal of this study is to develop an anti-scarring scaffold for treatment of large-area burn injuries. Materials and Methods: Hyaluronic acid sodium salt was covalently conjugated to anti-TNFα monoclonal antibody (anti-TNFα+HA) as previously described.[1] Following covalent conjugation, anti-TNFα mAB activity was analyzed via ELISA. Electrospinning was used to generate random fibrous PLCL scaffolds with an average fiber diameter of 6µm. Bovine type-I collagen was covalently attached to PLCL (ccPLCL). ccPLCL scaffolds were surgically inserted beneath skin grafts in a validated immune-competent murine HSc contraction model for 14 days, with comparison to skin graft alone or treatment with (anti-TNFα+HA). (anti-TNFα+HA) treatment groups contained 5% HA gel with approximately 400µg/mL anti-TNFα mAB. The gel was applied beneath skin graft at the time of surgery (single application group) and topically at 48h and 96h post-surgery (triple application group). Wounds were photographed daily and total wound area computed. Results: ELISA demonstrated that the activity of anti-TNFα mAB was not significantly affected by conjugation to HA. All data presented from animal studies are described in terms of percentage of original wound size, where 100% is the wound size at d0, and a fully contracted wound is 0% of its original size. All treatments were applied beneath a split-thickness skin graft. Murine wounds treated with skin grafts alone contracted to 50±9.5% at d14, wounds treated with a single application of anti-TNFα+HA contracted to 56±11%, while wounds treated with triple application of anti-TNFα+HA contracted to 64±8.0%. In contrast, wounds treated with ccPLCL scaffolds showed significantly decreased contraction of 82±1.2% at d14 (Fig 1). Discussion: At early time points, HSc contraction was significantly decreased in animals treated with either triple application of anti-TNFα+HA or ccPLCL scaffolds as compared to those treated with skin graft alone or single administration of anti-TNFα+HA. However, ccPLCL scaffolds showed a more effective inhibition of scar contraction at d14 as compared to all other groups. Conclusion: Conjugation of anti-TNFα+HA to PLCL may improve the inhibition of HSc contraction by combining the biochemical and mechanical cues to regulate the acute and chronic inflammatory events, respectively. Studies are ongoing to assess the synergistic effect of anti-TNFα+HA coating of PLCL scaffolds in vitro and in vivo.