Abstract
Despite significant advancements in treatment strategies, effective wound healing is still a global concern. In this study, we developed a hydrogel composed of gelatin methacryloyl (GelMA) and polyethylene glycol diacrylate (PEGDA) to sustainably release the growth factor FMS-like tyrosine kinase 3 ligand (FLT3L), intending to accelerate the healing process. FLT3L is a growth factor with known roles in immune cell development, especially dendritic cells. However, its potential effect on macrophages, particularly its role in the wound healing process, remains undiscovered. Macrophages are key regulators of wound healing, transitioning between pro-inflammatory (M1) and anti-inflammatory (M2) phenotypes to facilitate tissue repair. Macrophages are in the first line of defense against any foreign material found or placed inside the body, which is one of the reasons for the immune rejection of many medical treatments. In this study, we investigated the effects of FLT3L on macrophage behavior, focusing on proliferation, motility, and wound healing capability in both the absence and presence of GelMA/PEGDA hydrogels as a wound dressing medium. During our study, we noted substantial changes in macrophage behavior and characteristics when exposed to different concentrations of FLT3L. Particularly noteworthy were the shifts observed towards an M2-like phenotype, known for its involvement in tissue repair and anti-inflammatory processes. Among the various concentrations tested, our findings emphasized the significance of the 125 µg/ml concentration of FLT3L. This concentration demonstrated remarkable effects in modulating macrophage phenotype, striking a balance by promoting desired changes without triggering excessive cell proliferation or adverse reactions. In addition, various hydrogel compositions were explored to tweak their mechanical properties and ensure macrophage compatibility. Our other objective was to systematically assess various hydrogel compositions to find formulations boasting ideal mechanical characteristics, swelling tendencies, and compatibility with macrophages. Our thorough exploration of diverse hydrogel formulations found the hydrogel with the required performance in our intended application consists of 7.5% w/v GelMA and 1.5% w/v PEGDA. This formulation showcased favorable mechanical attributes, swelling behavior, and compatibility with bone marrow-derived macrophages. These findings provided a solid groundwork for our subsequent investigations into FLT3L loading and release kinetics. Having identified the optimal hydrogel formulation, our third aim was to assess the dynamics of FLT3L release from the loaded hydrogel and its influence on macrophage behavior. By incorporating FLT3L into the hydrogel and analyzing its release kinetics, we defined a sustained delivery profile conducive to prolonged therapeutic benefits. Additionally, we evaluated the impact of FLT3L released from the loaded hydrogel on macrophage phenotype, polarization, and functional responses. This investigation confirmed that the FLT3L-loaded hydrogel retained the attributes of both FLT3L and the hydrogel, exerting comparable effects on macrophages as they do individually. This study highlights the innovative function of FLT3L-loaded GelMA/PEGDA hydrogel in modulating macrophage activity and its potential impact on wound healing results. These findings open up exciting opportunities for future research and clinical applications, especially in developing topical medication formulations.