Ectopic models recapitulating morphological and functional features of articular cartilage.

Background: Articular cartilage is an extremely specialized connective tissue which covers all diarthrodial joints. Implantation of chondrogenic cells without or with additional biomaterial scaffolds in ectopic locationsin vivo generates substitutes of cartilage with structural and functional characteristics that are used in fundamental investigations while also serving as a basis for translational studies.

Methods: Literature search in Pubmed.

Results And Discussion: This narrative review summarizes the most relevant ectopic models, among which subcutaneous, intramuscular, and kidney capsule transplantation and elaborates on implanted cells and biomaterial scaffolds and on their use to recapitulate morphological and functional features of articular cartilage. Although the absence of a physiological joint environment and biomechanical stimuli is the major limiting factor, ectopic models are an established component for articular cartilage research aiming to generate a bridge between in vitro data and the clinically more relevant translational orthotopic in vivo models when their limitations are considered.