Implantation of bilayered plla scaffolds loaded with mesenchymal stem cells (MSCS) in a sheep model of osteochondral lesions

Abstract

[EN] Purpose: Cartilage injuries are poorly repaired after surgery, since cartilage is a tissue with a very limited capacity to regenerate. Apart from other surgical attempts, autologous chondrocyte implantation (ACI) was the first cell therapy approach developed for these kinds of lesions. Chondrocyte usage nevertheless is limited by the dedifferentiation occurred when expanded in monolayer. Bone marrow-derived Mesenchymal Stem Cells (MSC) emerge as ideal cells to be implanted in the site of cartilage lesions.

Methods: Here we use MSC to treat sheep cartilage lesions implanted in the upper cartilage layer of bilayered PLLA scaffolds, which hold a lower layer enriched with Hydroxiapatite to facilitate osteointegration of the scaffold.

Results: After evolutions of 1.5, 3 and 6 months, lesions showed a slight but non significant decrease in the mankin score for cartilage found in the lesioned area (in animals treated with unloaded and cell loaded scaffolds) suggesting a progressive degradation of the tissue. Nevertheless, staining with Safranine-O showed the presence of more cartilaginous tissue in animals evolve for 6 months with MSC loaded scaffolds, demonstrating a more regeneration of the tissue when MSC were implanted in cartilage lesions. Unfortunately new formed tissue did not appear in the cartilage layer, but inside the hole performed during surgery, which might suggest some incapacity of the scaffold to support the presence of cells aligned with the surface in order to integrate tissue to the surrounding cartilage. Finally, collagen type II and aggrecan were found in the regenerated tissue.

Conclusions: The use of MSCs is a promising alternative for the treatment of cartilage damage, but administration in the core of scaffolds needs to be improved.