Examination of the effect of xenogeneic mesenchymal stem cells and conditioned medium on cartilage graft viability: a rabbit model

Abstract

Background Since cartilage, unlike skin, does not contain vessels, it obtains nutrition by diffusion. This reduces graft viability, resulting in problems such as reductions in size, changes in shape, and resorption of the cartilage graft in the late post-graft period. This study aimed to investigate the effects of adipose-derived mesenchymal cells and conditioned medium (CM) on cartilage graft viability.Methods Dissections were performed 4 months after the injection of 0.5 mL of CM or 2×10<sup>6</sup> mesenchymal stem cells (MSCs) in 0.5 mL after grafting into a control group and two experimental groups (n=21 rabbits in total). Chondrocyte viability and type II collagen expression in the grafted areas were analyzed by hematoxylin-eosin staining and immunohistochemical methods, respectively.Results In the MSC and CM groups, chondrocyte proliferation at the graft tissue incision margin (MSC: P<0.01, CM: P<0.0001), chondrocyte proliferation at the auricular cartilage incision margin (MSC: P<0.05, CM: P<0.0001), integration of the graft with the surrounding cartilage (MSC: P<0.001, CM: P<0.0001) and type II collagen expression levels (MSC: P=0.001, CM: P=0.0002) significantly increased.Conclusions Xenogenic injection of MSCs and CM contributed to new cartilage production without any tumoral effects or immune reactions. In particular, the cell-free nature of CM strengthened its potential for safe use. Since injections of MSC and CM can preserve cartilage graft viability, interest in this technique is expected to increase as long-term results from clinical studies on the subject become available.