Gellan gum/Gellan gum-hydroxyapatite Hydrogel Bilayered Scaffolds for Osteochondral Tissue Engineering: In Vitro Study

In the last few years, it is belief that bilayered scaffolds are advantageous as compared to single-layer when it is envisioned treating osteochondral (OC) defects. Gellan gum (GG) has shown great promise in
different tissue engineering (TE) strategies, since it is non-cytotoxic and allows obtaining gels able to encapsulate cells. In this study, we developed bilayered gellan gum/gellan gum-hydroxyapatite (GG/GG-HAp)
hydrogel scaffolds for application in OC TE. The cartilage-like layer was obtained from 2 wt% low acyl GG solutions, while the bone-like layer was produced by adding a 2 wt% GG solution to different amounts of
HAp (5-20 wt%). The mechanical properties of the bilayered scaffolds were investigated by dynamic mechanical analysis at pH 7.4 and 37ºC. Degradation and water uptake profiles were performed by soaking the
scaffolds in a phosphate buffered saline solution_PBS (pH 7.4) up to 30 days. Bioactivity was also investigated by soaking the bilayered scaffolds in a simulated body fluid solution up to 14 days.
In vitro studies were performed to screen possible cytotoxicity of the bilayered hydrogels using a L929 cell line. The osteogenesis and chondrogenesis were evaluated by encapsulating human osteoblasts and
human chondrocytes in the bone-like layer and cartilage-like layer, respectively. Viability of both cell type was assessed by Live/dead assay. Moreover ATP assay was performed in chondrocytes encapsulation.