Self-crosslinking effect of chitosan and gelatin on alginate based hydrogels: Injectable in situ forming scaffolds

Injectable in situ forming hydrogels has great potential in tissue engineering. Simple and easy preparation of these hydrogels with low toxicity and stability is a great advantage. In the present study, two types of self-crosslinking in situ forming alginate based hydrogels with different formulation were synthesized, characterized and compared in order to introduce an optimal injectable scaffold in minimally invasive applications in tissue engineering. To this end, the hydrogels consist of oxidized alginate (AD), polyethylene glycol (PEG) and carboxymethyl chitosan (CMC) or gelatin (GEL) was synthesized. The hydrogels were assessed by many techniques including microscopy, spectroscopy, compressive analysis, injectability, rheological analysis and cell viability to ascertain hydrogel properties. In comparison with AD/PEG-GEL hydrogel, AD/PEG-CMC hydrogel showed a higher compressive modulus, viscosity and injection time, whereas AD/PEG-GEL hydrogel displayed a higher degree of crosslinking. Due to the rheological behavior of AD/PEG-CMC hydrogel, this composition was more suitable for the injectable application. The hydrogels, despite the composition, showed the ability to survive and proliferate mesenchymal stem cells based on cytotoxicity assays. With respect to rheological, degradation time and compressive properties of the above-mentioned hydrogels, AD/PEG-CMC hydrogel could be considered as an appropriate candidate for injectable self-crosslinking application in tissue engineering.