An in situ forming gelatin-based hydrogel loaded with soluble amniotic membrane promotes full-thickness wound regeneration in rats

Objective(s): Early effective treatment and appropriate coverage are vital for full-thickness wounds. Amnion membrane-derived products have recently emerged in tissue engineering. However, the optimal concentration, carrier for controlled release, and handling have remained challenges. This study aims to develop and optimize an in situ forming, amniotic-based hydrogel for wound healing.Materials and Methods: Here, a composite matrix was fabricated with gelatin hydrogel modified with methacrylate functional group conjugated (GelMA) and keratose (wt.1%), loaded with mesenchymal stem cells (MSCs, 1×105 cell/ml) and optimized soluble amniotic membrane (SAM, 0.5 mg/ml). The physicochemical properties of the final subject were evaluated in vitro and in vivo environments. Results: The results of the in vitro assay demonstrated that conjugation of the methacryloyl group with gelatin resulted in the formation of GelMA hydrogel (26.7±1.2 kPa) with higher mechanical stability. Modification of GelMA with a glycosaminoglycan sulfate (Keratose) increased controlled delivery of SAM (47.3% vs. 84.3%).  Metabolic activity (93%) and proliferation (21.2 ± 1.5 µg/ml) of MSCs encapsulated in hydrogel improved by incorporation of SAM (0.5 mg/ml). Furthermore, the migration of fibroblasts was facilitated in the scratched assay by SAM (0.5 mg/ml)/MSCs (1×105 cell/ml) conditioned medium. The GelMA hydrogel groupes revealed regeneration of full-thickness skin defects in rats after 3 weeks due to the high angiogenesis (6.3 ± 0.3), cell migration, and epithelialization. Conclusion: The results indicated in situ forming and tunable GelMA hydrogels containing SAM and MSCs could be used as efficient substrates for full-thickness wound regeneration.