Preparation and characterization of an injectable dexamethasone-cyclodextrin complexes-loaded gellan gum hydrogel for cartilage tissue engineering.

In this study, 6-(6-aminohexyl) amino-6-deoxy-β-cyclodextrin-gellan gum complex hydrogel (HCD-GG) was developed to enhance the affinity of anti-inflammatory drug dexamethasone (Dx), improve chondrogenesis, and decrease the inflammatory response. The modified chemical structure was confirmed by NMR and FTIR. Mechanical and physicochemical properties were characterized by performing viscosity study, compression test, injection force test, swelling kinetic, weight loss, and morphological study. The release profile of the drug-loaded hydrogels was analyzed to confirm the affinity of the hydrophobic drugs and the matrix and characterize cumulative release. In vitro test was carried out with MTT assay, live/dead staining, glycosaminoglycan (GAGs) content, double-stranded DNA (dsDNA) content, morphological analysis, histology, and gene expression. In vivo experiment was conducted by implanting the samples under a subcutaneous area of SPD rat and cartilage defected rabbit model. The results displayed successfully synthesized HCD-GG. The gelation temperature of the modified hydrogels was decreased while the mechanical property was improved when the drug was loaded in the modified hydrogel. Swelling and degradation kinetics resulted in a higher level compared to the pristine GG but was a sufficient level to support drugs and cells. The affinity and release rate of the drug was higher in the HCD-GG group which shows an improved drug delivery system of the GG-based material. The microenvironment provided a suitable environment for cells to grow. Also, chondrogenesis was affected by the existence of Dx and microenvironment, resulting in higher expression levels of cartilage-related genes while the expression of the inflammation mediators decreased when the Dx was loaded. In vivo study showed an improved anti-inflammatory response in the drug-loaded hydrogel. Furthermore, the cartilage defected rabbit model showed an enhanced regenerative effect when the Dx@HCD-GG was implanted. These results suggest that HCD-GG and Dx@HCD-GG have the potential for cartilage regeneration along with multiple applications in tissue engineering and regenerative medicine.