Background: Multipotent mesenchymal stromal cells (MSCs) are of particular interest for their potential clinical use in cartilage engineering but a consistent model is missing in large animals.<p< Objective: In absence of any detailed study reporting a complete characterization of the mesenchymal cells isolated from sheep bone marrow, we fully characterized the adherent stromal cells and developed a pre-clinical model of cartilage engineering by implantation of autologous MSC in the Merinos sheep.
Methods: oMSC were isolated from bone marrow, expanded and further characterized according to the recently proposed definition of the MSC. The experimental model consists in partial-thickness lesions created in the inner part of the patellae of the posterior legs. Lesions were filled with oMSC ± chitosan ± TGFβ-3 in a fibrin clot.
Results: Ovine MSC (oMSC) were shown to display the three main characteristics of MSC: adherence to plastic, phenotypic profile (positive for CD44, CD105, vimentin and negative for CD34 and CD45) and trilineage differentiation potential. We also report two other important functional characteristics of MSC: support of long term hematopoiesis and immunosuppressive capacity. In vivo, two months after implantation, the histological analysis revealed chondrocyte-like cells surrounded by a hyaline-like cartilaginous matrix that was integrated to the host cartilage when oMSC were combined with chitosan and TGFβ-3.
Conclusions: This study provides for the first time a strong characterization of oMSC and establishes the basis for a model of cartilage engineering in a large animal.
- cartilage repair
- haematopoiesis support
- multipotent stromal stem cell