Synthesis, characterization, and application potential of chitosan/acrylamide composite hydrogels as skin expanders

Hydrogels are currently widely used in regenerative medicine and wound repair due to their superior biocompatibility, reliable mechanical strength, and good morphological memory. We aimed to prepare a self-expanding hydrogel that can be used as a skin expander for the repair of large soft skin tissue defects. Self-expanding hydrogels were prepared by chemical cross-linking, which consisted of water-soluble chitosan (CS), acrylamide (AM), methylene bisacrylamide (NMBA), etc. Five groups of in vitro experiments, including (CS-AM) of 0% (pure AM group), 13.9%, 27.8%, 41.7%, and 55.6%, were conducted to determine mechanical properties, swelling properties, cytotoxicity, etc. In the rat model, both a tight skin area (neck) and a loose skin area (back) were selected for expansion with hydrogels. A total of 27.8% of the CS-AM samples expanded stably under the skin of the rats, achieving 370% expansion in the tight zone and 490% expansion in the flaccid zone. Subcutaneous histopathological examination suggested that the inflammation index of the pericolloid tissue was lower in the CS-AM group than in the pure AM group. Our results demonstrate that self-expanding CS-AM hydrogels have great potential for application as skin expanders.