Influence of Gelatin on Characteristics of Enzymatically Cross-Linkable Alginate as a Promising Injectable Hydrogel for TissueEngineering Applications

Background and Aim: Alginate, a natural polysaccharide, is one of themost common biomaterials due to its abundance, biocompatibility, andgentle cross-linking procedure. However, the stability of alginate capsulesgenerally weakens over time due to exposure to certain species in thecell culture medium. Modification of alginate with phenol moieties (Alg-Ph), which can be gel enzymatically with horseradish peroxidase (HRP)in the presence of peroxide hydrogen, can increase alginate hydrogelstability in the cell culture medium.Methods: In this work, alginate was modified by tyramine hydrochloridein the presence of EDC/NHS for 1 day at 25°C. To provide adhesivemotifs, gelatin was added to the enzymatically-gellable alginate andthe obtained hydrogel (Alg-Ph-Gel) was characterized by SEM, gelationtime, enzymatic degradation, mechanical and swelling properties as wellas water vapor loss for use in cartilage tissue engineering applications.Chondrocytes (at X0 = 2×106 cells/mL gel) were cultured for 14 days andMTT assay was used for cell activity measurements. Direct subcutaneousimplantation of the cell-laden hydrogels, as well as the hydrogels withoutcells, was carried out in rats and H & E staining was performed after 1month.Results: SEM images showed the addition of gelatin could increase theuniformity of the pore sizes inside the Alg-Ph-Gel hydrogels. Alg-Ph-Gelhydrogels also showed higher gelation time, degradation rate, as wellas swelling properties as the hydrogels, swelled 1.6- fold more than theAlg-Ph hydrogels after 72 h in PBS. However, mechanical strength (1.7-fold), as well as water vapor loss, decreased for the Alg-Ph-Gel hydrogels.Chondrocyte cells cultured in the Alg-Ph-Gel hydrogels could maintaintheir original phenotype and proliferate more than 1.4-fold higher thanthe cells cultured in the Alg-Ph hydrogels after 14 days (P < 0.05). Thesubcutaneous hydrogels could be identified readily without completeabsorption and signs of toxicity or any untoward reactions after 1 month.Viable chondrocyte cells inside globular aggregates were seen as redcoloredareas in the cell-laden hydrogels.Conclusion: The study demonstrates that gelatin can improve theenzymatically-gellable alginate hydrogels for cartilage tissue engineeringapplication.

کلیدواژه ها:

Tissue engineering ، Alginate ، Gelatin ، Stem cells ، Hydrogel