15502-m-pleumeekers

ABSTRACT Cartilage tissue engineering can offer promising solutions for restoring defected cartilage in the head and neck area and has the potential to overcome limitations of current treatments. However, to generate a construct of reasonable size, large numbers of chondrocytes are required, which limits its current applicability. Therefore, we evaluate the suitability of a combination of cells for cartilage regeneration: bone-marrow-derived mesenchymal stem cells and ear or nasal chondrocytes. Human bone-marrow-derived mesenchymal stem cells were encapsulated in alginate hydrogel as single-cell-type populations or in combination with bovine ear or nasal chondrocytes at a 80:20 ratio. Constructs were either cultured in vitro or directly implanted subcutaneously in mice. Cartilage formation was evaluated with biochemical and biomechanical analyses. The use of a xenogeneic co-culture system enabled the analyses of the contribution of the individual cell types using species-specific gene-expression analyses. In vivo , constructs containing a combination of human bone-marrow-derived mesenchymal stem cells with bovine ear or nasal chondrocytes contained similar amounts of cartilage components to that of constructs containing chondrocytes only (i.e. bovine ear and nasal chondrocytes). In vitro , species-specific gene-expression analyses demonstrated that chondrogenic gene ACAN was expressed by the chondrocytes only, which suggests a more trophic role for human bone-marrow-derived mesenchymal stem cells. Furthermore, the additional effect of human bone-marrow-derived mesenchymal stem cells was more pronounced in combination with bovine nasal chondrocytes. By supplementing low numbers of bovine ear or nasal chondrocytes with human bone- marrow-derived mesenchymal stem cells, we were able to engineer cartilage constructs with similar properties to that of constructs containing chondrocytes only. This makes the procedure more feasible for future applicability in the reconstruction of cartilage defect in the head and neck area since less chondrocytes are required. 108 CHAPTER 6