Aims: Cartilage lesions do not repair spontaneously. Despite the high number of surgical and tissue engineering approaches that have been applied to promote articular cartilage (AC) regeneration, none of them, at present, have shown durable satisfactory results. In the present study an innovative technology, the RCCS™ bioreactor (Synthecon, Inc.), was employed to develop a 3D culture model suitable for the long-term in vitro maintenance of AC explants. Based on the principle of relative microgravity, the RCCS™ bioreactor, in fact, creates a microenvironment that, by preserving the complexity of original cell-cell and cell-matrix interactions, closely mimics the original tissue-specific biophysical conditions needed for proper cellular activities and morphogenesis.

Methods: Newborn rabbits were used as AC donors (femoral head). The explants, collected under sterile conditions and sectioned into 1–3 mm³ fragments, were immediately processed for structural/molecular analyses (T0) or kept for up to 4 weeks in the RCCS™ bioreactor (3D culture). The cultured fragments were harvested after 2, 4, 7 days and after 2, 3 and 4 weeks of culture. Comparative histochemical and molecular analyses were then performed on samples from each experimental point to assess the viability/differentiation pattern of their cellular components, as well as the structural integrity of the extracellular matrix.

Results: Our results demonstrated that, for the whole period of culture, the samples maintain the typical features of hyaline AC, with no significant signs of cell suffering or degenerative changes.

Conclusions: The dynamic 3D culture model employed in our study open promising perspectives either for providing new insight into AC physiopathology, or for developing efficacious intervention strategies for the treatment of AC disorders.