In vivo performance of gellan gum-based structures: A comparison study between hydrogels and spongy-like scaffolds for osteochondral tissue regeneration

The orthopaedic field has been facing challenging difficulties when it comes to regeneration of large defects as found in osteochondral defects (OC). Autologous osteochondral mosaicplasty has been used as valid option for OC treatment. But donor site morbidity remains a big issue with most used autografts [1]. Promising strategies for the regeneration of large osteochondral defects (Grade 4) implies the application of biomaterials, growth factors, and cells alone or in combination. But the ideal treatment remains unclear. Our group has been proposed bilayered structures to regenerate osteochondral defects [2]. The underlying hypothesis of our study was to compare the in vivo responses of bilayered hydrogels and spongy-like hydrogels applied as 3D implants for OCD regeneration following an acellular strategy. Both structures (hydrogels and spongy-like) present the same backbone material. However different physical properties due to the different processing methods can imply a different response in OCD regeneration. The study was investigated using two different in vivo models. The subcutaneous inflammatory response was assessed in mice model and the materials performance such as materials stability, cellular behavior, cells and macrophages infiltration, matrix deposition and new bone and cartilage formation assessed in rabbit critical size OCD model.