The purpose of this work was to create an in vitro model of tissue-engineered cartilage structure produced by isolated swine articular chondrocytes, expanded in culture and seeded onto a biological scaffold.

Swine articular chondrocytes were enzymatically isolated from pig joints and expanded in monolayer culture. When confluence was reached, cells were resuspended and seeded in vitro onto biological collagen scaffolds for 3, 4 and 6 weeks. Samples were retrieved from the culture and analysed macroscopically and biomechanically by compressive test. Gross evaluation was performed by simple probing, sizing and weighing the samples at all time periods. A baseline of the values was also recorded at time 0. Then, samples were biomechanically tested by unconfined compression and shear tests. Finally, the samples were fixed in 4% paraformaldehyde and processed for histological evaluation. Some samples were stained with Safranin-o, and some others subjected to immunostaining analysis for type II collagen.

Upon retrieval, samples showed dimensional enlargement and mass increase over time and gross mechanic integrity by simple probing. A biomechanical test demonstrated an initial reduction in the values of compressive and shear parameters, followed by a consistent increase throughout the tested time points. Histology showed cartilage-like tissue maturing over time within the biological scaffold.

The results from this study demonstrate that isolated chondrocytes could be seeded onto a biological collagen scaffold, producing cartilage-like matrix with tissue-specific morphology and biomechanical integrity. This tissue-engineered cartilage structure is easily reproducible and it could represent a valuable model for studying the behaviour of different variables on the newly formed cartilage.