Bioprinting of GelMA - Phycocyanin hydrogels for chondrogenic differentiation

Abstract

Osteoarthritis (OA) is a common and severe joint disease characterized by disruption of the inflammatory process, leading to degradation of cartilage and surrounding tissues. Its onset is still not completely understood, and current treatments are not only limited but also potentially harmful due to severe adverse effects (e.g., infections or renal toxicity). Among the consequences of OA, the dedifferentiation of chondrocytes - the sole cell type in cartilage - is of particular concern, as the loss of their native phenotype further aggravates cartilage damage. One potential strategy to address this issue is the use of hydrogels. Their 3D structure can mimic the native cartilage environment and influence both cell differentiation and regenerative cascades. In addition, phycocyanin (PC), a photosynthetic pigment and protein widely consumed as a food supplement, has demonstrated strong anti-inflammatory effects as well as other beneficial properties, including applications in tissue engineering. This study investigates the effects of PC in an inflammatory model composed of IL-1β (1ng/mL) and TNF-α (25ng/mL), designed to simulate OA pathophysiology. It also evaluates the ability of PC to promote chondrocyte redifferentiation when incorporated into gelatin methacryloyl (GelMA), a promising biomaterial, to create a novel bioink. PC toxicity was assessed at concentrations up to 200 μg/mL using Alamar Blue and CCK-8 assays, with no significant effect on cell growth. In a 2D culture model, PC reduced inflammation in stimulated chondrocytes, as shown by decreased Nf-κB staining, although qPCR results were less conclusive. The bioink was then prepared by mixing PC (100 μg/mL) with 10% GelMA, the standard working concentration in the group. Hydrogel constructs showed comparable viability to GelMA-only controls, while gene expression analysis revealed complex patterns related to chondrocyte maturation. Finally, printability tests indicated that viability was largely preserved, although a cluster effect (numerous chondrocyte aggregates) was observed. In conclusion, this work represents a first step toward developing a biofunctional material with potential to advance cartilage tissue engineering, by supporting chondrocyte redifferentiation, as well as OA modeling.