Immunocompatibility of poly(ethylene glycol)-penetrated alginate–chitosan hydrogels

Scaffold-guided tissue regeneration using hydrogels has been emerging as an ideal alternative for the management of terminal-stage organ damage. Design of scaffolds for tissue regrowth mainly focuses on their immuno/biocompatibility as well as physiochemical characteristics. The focus of this study is on the biocompatibility evaluations of a panel of four hydrogel scaffolds fabricated using alginate, chitosan and hydroxyapatite reinforced with poly(ethylene glycol). The hydrogels were subsequently cross-linked with calcium ions and glutaraldehyde. Immunocompatibility was assessed by interacting Raw 264.7 cell lines with these hydrogels. MTT cell viability assay revealed the non-cytotoxic nature of the hydrogels, and the macrophages grown in contact with the hydrogels exhibited no alteration in their morphology and were similar to the untreated normal cells. The concentration of nitric oxide, activity of myeloperoxidase and the messenger ribonucleic acid transcripts of proinflammatory cytokines, interleukin 6 and tumour necrosis factor alpha exhibited no considerable increase in the macrophages cultured with the hydrogels when compared to lipopolysaccharide-stimulated cells. In short, the absence of macrophage activation on contact with hydrogels is a clear indication of their in vitro immunocompatibility, suggesting their potential application as tissue engineering templates.