Hydrogels as Therapeutic Delivery Vehicles for Wound Healing

Diabetes is one of the major systemic causes of delayed wound healing. Exploiting scaffolds as mediums to facilitate wound healing can be a modality to reestablish normal tissue structure, or engineer the tissue back to normal. This study utilizes an animal model to look at the potential of enhancing wound healing using hydrogel scaffolds. The aim of this study is to determine the effect of a peptide self-assembling leucine zipper gel, as compared to other established hydrogels, on wound healing in diabetic mice. Four hydrogel scaffolds were prepared for utilization in this study including, pluronic F-127 gel, chitosan gel, leucine zipper gel-control, and leucine zipper-RGD gel. Pluronic gel preparation was at time of application and the remaining three were previously prepared (Dr. Ann George’s laboratory). Four groups of mice with 6 mice in each group, (n=6) were evaluated for wound closure. An additional four groups with 2 mice in each group (n=2) were used for histological sampling. Two 8mm diameter full thickness circular excisional wounds were prepared with biopsy punch instruments on the dorsal surface of each mouse. One wound was treated with approximately 100μl of a hydrogel and the other untreated wound served as a control. The wounds were evaluated, examined for any abnormalities, and photographed on day 0, 4, 6, 8, 12, 14, and 16. The surface area of each wound was measured using computer software (Axiovision, Carl Zeiss Microimaging GmbH, Germany). On day 16 the mice were sacrificed. The groups designated for histological examination were sacrificed on day 8 and 16. Wound samples from experimental and control mice were paraffin embedded, sectioned, and stained with hematoxilin and eosin and Masson’s trichrome. The wound closure data was analyzed using 2-way ANOVA. Wound closure showed statistically significant difference between gels and controls or between the gels. More importantly both leucine zipper gels showed no difference when compared to each other. This was further supported by histological findings demonstrating similar findings between control and experimental sites. The leucine zipper gels did not show any difference from their corresponding controls or the other hydrogels. These results indicate that the peptide self assembling leucine zipper gel has no adverse affect on wound healing in diabetic mice when compared to other well established scaffold hydrogels. Therefore there is great potential for the leucine zipper hydrogel to help in improving delayed wound healing by incorporating various active motifs. This hydrogel can act as a carrier for any number of factors that could help in enhancing regeneration and healing.