Development of Amniotic Epithelial Stem Cells Secretome-Loaded Inverse Electron Demand Diels-Alder-Cross-Linked Hydrogel as a Potential Immunomodulatory Therapeutical Tool.

Amniotic epithelial stem cells (AEC) hold potential for tissue regeneration, especially through their conditioned medium (AEC-CM) due to their immunomodulatory and regenerative effects. Nevertheless, advanced drug delivery systems such as hydrogels are needed to enable clinical applications. Herein, an gellable hyaluronic acid and polyethylene glycol-based iEDDA-cross-linked hydrogel was developed for the encapsulation and controlled release of AEC-CM. The developed system was formed by norbornene-modified hyaluronic acid and tetrazine-modified polyethylene glycol functionalized with heparin. The hydrogel was formed by mixing both precursor polymers, displaying fast cross-linking kinetics and showcasing a highly porous inner structure and low swelling properties. Moreover, the heparin-functionalized system allowed the sustained release of predominant growth factors from AEC-CM over 14 days. studies in peripheral blood mononuclear cells (PBMCs) showed an enhanced suppression efficacy and a significant shift toward the M2 macrophage phenotype in comparison with nonencapsulated AEC-CM. Therefore, this work provides a suitable alternative for the encapsulation of AEC-CM in a hydrogel formulation, highlighting its potential as an alternative immunomodulatory therapeutic tool for tissue regeneration.