Moisture wound healing characteristics of alginate sponge and hydrogel

Alginate sponge and hydrogel were prepared by a drying/crosslinking method and their wound healing characteristics were investigated comparatively. The alginate hydrogel had a higher equilibrium water content than the sponge, providing a moist wound healing condition without absorbing exudate from a wound. The amounts of proinflammatory cytokines released by macrophages were lowered due to the cytokine-binding effects of the alginate sponge and hydrogel. The hydrogel lowered the cytokine level more dominantly than the sponge, suggesting that the affinity of alginate molecules to cytokines increases at a more swollen state. The hydrogel allowed superior wound healing and contraction at the early stage of application. However, epithelialization was conspicuous when the sponge was applied. It was confirmed through histological examination and RNA expression analysis that angiogenesis, formation of collagen fibers, regeneration of epithelium, and production of protein were promoted using the alginate sponge and hydrogel as wound dressing materials.