Objectives: This study was intended to verify the likelihood of homing of intra-articularily injected mesenchymal stem cells (MSCs) and its involvement in the healing process of experimentally induced, acute and chronic, partial chondral defects in dogs.
Methods: Partial thickness chondral defects were created on the lateral femoral condyle of stifle joint in domestic mongrel dogs. MSCs were harvested in a separate procedure, labelled with green fluorescent protein (GFP) using monster GFP vector and suspended in buffer phosphate solution for intra-articular (IA) injection. Dogs were divided into three groups. Group I, served as the control. The dogs in the two cell-treated groups received a single IA injection of MSCs one day (Group II) and one month (Group III) after creating the defect. Sacrifice was scheduled at 2 and 8 weeks post-surgery for group I, and 2 and 8 weeks post-treatment, for the cell-treated groups. Morphological, histological, and fluorescence analysis was performed.
Results: Recovery was significant both clinically and histologically in the two cell-treated groups (Group II and III) compared to the control (Group I), (p<0.001). In the meantime, Group-II showed better results at 8 weeks than Group III (p=0.01). Homing was confirmed by the incorporation of injected GFP-labelled MSCs within the newly formed cartilage.
Conclusions: The obtained results prove that the use of IA injection of autologous MSCs is a viable option for treating partial cartilage defects. Cell labelling gave evidence to the certainty of cell homing within the neocartilage of all treated cases and the participation in the reparative process.