Prajapati, T. J. | bioRxiv Science

bioRxiv2022

Engineering Antioxidant and Oxygen-Releasing Lignin Composites to Accelerate Wound Healing

The application of engineered biomaterials for wound healing has been pursued since the beginning of tissue engineering. Here, we attempt to apply functionalized lignin to confer antioxidation to the extracellular microenvironments of wounds and to deliver oxygen from the dissociation of calcium peroxide for enhanced vascularization and healing responses without eliciting inflammatory responses. Elemental analysis showed 17 times higher quantity of calcium in the oxygen releasing nanoparticles. Lignin composites including the oxygen releasing nanoparticles released around 500 ppm oxygen per day at least for 7 days. By modulating the concentration of the methacrylated gelatin, we were able to maintain the injectability of lignin composite precursors and the stiffness of lignin composites suitable for wound healing after photo-crosslinking. In situ formation of lignin composites with the oxygen releasing nanoparticles enhanced the rate of tissue granulation, the formation of blood vessels and the infiltration of -smooth muscle actin+ fibroblasts into the wounds over 7 days. At 30 days after surgery, the lignin composite with oxygen generating nanoparticles remodeled the collagen architecture resembling to the reticular pattern of unwounded collagen with minimal scar formation. Thus, our study shows the potential of functionalized lignin for wound healing applications requiring balanced antioxidation and controlled release of oxygen for enhanced tissue granulation, vascularization and maturation of collagens.

bioengineering↗

bioRxiv2022

Endogenous IL-10 Contributes to Wound Healing and Regulates Tissue Repair

BackgroundInterleukin-10 (IL-10) is essential in fetal regenerative wound healing and likewise promotes a regenerative phenotype in adult dermal wounds. However, the role of endogenous IL-10 in postnatal dermal wound healing is not well established. We sought to determine the role of IL-10 in murine full thickness, excisional wounds that are splinted to prevent contracture and mimic human patterns of wound closure. MethodsFull thickness, excisional wounds were made in wildtype (WT) and IL-10-/- mice on a C57BL/6J background (F/M, 8wks old). In a subset of wounds, contraction was prevented by splinting with silicone stents (stenting) and maintaining a moist wound microenvironment using a semi-occlusive dressing. Wounds were examined for re-epithelialization, granulation tissue deposition, and inflammatory cell infiltrate at day 7 and fibrosis and scarring at day 30 post-wounding. ResultsWe observed no difference in wound healing rate between WT and IL-10-/- mice in either the stented or unstented group. At day 7, unstented IL-10-/- wounds had a larger granulation tissue area and more inflammatory infiltrate than their WT counterparts. However, we did observe more F4/80+ cell infiltrate in stented IL-10-/- wounds at day 7. At day 30, stented wounds had increased scar area and epithelial thickness compared to unstented wounds. ConclusionsThese data suggest that endogenous IL-10 expression does not alter closure of full thickness excisional wounds when wound hydration and excessive contraction are controlled. However, the loss of IL-10 leads to increased inflammatory cell infiltration and scarring. These data suggest that previous reports of increased rates of healing in IL-10-/- mice ought to be revisited considering recent advances in wound healing models. Moreover, these new findings suggest that IL-10 contributes to regulation of inflammation without compromising the healing response.

molecular biology↗