Preclinical Evidence of Intra-Articular Autologous Cartilage Micrograft for Osteochondral Repair: Evaluation in a Rat Model.

Objective: The search for an effective and long-lasting strategy to treat osteochondral defects (OCD) is a great challenge. Regenerative medicine launched a new era of research in orthopaedics for restoring normal tissue functions. The aim of this study was to test the healing potential of Rigenera micrografting technology in a rat model of OCD by investigating 2 cartilage donor sites.

Methods: Full-thickness OCD was bilaterally created in the knee joints of rats. Animals were randomly divided into 2 groups based on the anatomical site used for micrograft collection: articular (TO) and xiphoid (XA). Micrograft was injected into the knee via an intra-articular approach. The contralateral joint served as the control. Euthanasia was performed 2 months after the set-up of OCD. Histological evaluations foresaw hematoxylin/eosin and safranin-O/fast green staining, the modified O'Driscoll score, and collagen 1A1 and 2A1 immunostaining. Kruskal-Wallis and the Dunn test were performed to evaluate differences among groups.

Results: Histological results showed defect filling in both autologous micrografts. The TO group displayed tissue repair with more hyaline-like characteristics than its control ( < 0.01). A fibrocartilaginous aspect was instead noticed in the XA group. Immunohistochemical assessments on type 2A1 and type 1 collagens confirmed the best histological results in the TO group.

Conclusions: TO and XA groups contributed to a different extent to fill the OCD lesions. TO group provided the best histological and immunohistochemical results; therefore, it could be a promising method to treat OCD after the validation in a larger animal model.