Biofabrication of an <i>in situ</i> hypoxia-delivery scaffold for cartilage regeneration

Osteoarthritis (OA) is a debilitating joint condition affecting millions of people worldwide, triggering painful chondral defects (CDs) that ultimately compromise the overarching patients' quality of life. Currently, several reconstructive cartilage techniques (RCTs) (i.e.: matrix-assisted autologous chondrocytes implantation has been developed to overcome the total joint replacement limitations in the treatment of CDs. However, there is no consensus on the effectiveness of RCTs in the long term, as they do not provide adequate pro-regenerative stimuli to ensure complete CDs healing. In this study, we describe the biofabrication of an innovative scaffold capable to promote the CDs healing by delivering pro-regenerative hypoxic cues at the cellular/tissue level, to be used during RCTs. The scaffold is composed of a gelatin methacrylate (GelMA) matrix doped with hypoxic seeds of GelMA functionalized with a fluorinated oxadiazole (GelOXA), which ensures the delivery of hypoxic cues to human articular chondrocytes (hACs) embedded within the scaffold. We found that the GelMA/GelOXA scaffold preserved hACs viability, maintained their native phenotype, and significantly improved the production of type II collagen. Besides, we observed a reduction in type I and type X collagen, characteristic of unhealthy cartilage. These findings pave the way for the regeneration of healthy, hyaline-like cartilage, by delivering hypoxic cues even under normoxic conditions. Furthermore, the GelMA/GelOXA scaffold's ability to deliver healing signals directly to the injury site holds great potential for treating OA and related CDs, and has the potential to revolutionize the field of cartilage repair and regenerative medicine.