The effect of PEGT/PBT scaffold architecture on oxygen gradients in tissue engineered cartilaginous constructs

Repair of articular cartilage defects using tissue engineered constructs composed of a scaffold and cultured autologous cells holds promise for future treatments. However, nutrient limitation (e.g. oxygen) has been suggested as a cause of the onset of chondrogenesis solely within the peripheral boundaries of larger constructs. In the present study, oxygen gradients were evaluated by microelectrode measurements in two porous polyethylene glycol terephthalate/polybutylene terephthalate (PEGT/PBT) scaffold architectures, a compression-molded and particle-leached sponge (CM) and a 3D-deposited fiber (3DF) scaffold. During the first 14 days in vitro, gradients intensified, after which a gradual decrease of the gradients was observed in vitro. In vivo, however, gradients changed instantly and became less pronounced. Although similar gradients were observed regardless of scaffold type, significantly more cells were present in the center of 3DF constructs after 2 weeks of in vivo culture. Our results stress the importance of a rationally designed scaffold for tissue-engineering applications. Organized structures, such as the 3DF PEGT/PBT polymer scaffolds, offer possibilities for regulation of nutrient supply and, therefore, hold promise for clinical approaches for cartilage repair.