Hyaluronan-based scaffold for cartilage repair: from autologous chondrocytes to bone marrow concentrated cells

Articular cartilage is a highly organized tissue lacking self-regeneration capacity due to avascularization. Autologous chondrocyte transplantation by means of cell isolation, expansion and implantation has been employed to treat cartilage lesions. The use of suitable biomaterial such as a hyaluronan-based scaffold has greatly improved this therapeutical strategy giving interesting results regarding both the characteristics of the regenerated tissue and the good clinical condition of the patients treated. However, this procedure is associated with several disadvantages, including donorsite morbidity and the use of two surgical interventions. Advances in cellular cultures have provided new and interesting strategies based on the use of mesenchymal stem cells. These cells represent a fascinating source for regenerative medicine since they can be easily isolated from bone marrow and or from other tissues, expanded in vitro and differentiated with the use of suitable growth factors also in the chondrogenic sense. Recently, taking into account that mesenchymal stem cell activity is not due only to the expression of one or more intrinsic cell capabilities but depends also upon the surrounding microenvironment (or “niche”), it has been suggested that the bone marrow could be transplanted in toto. In fact, bone marrow contains not only stem cells and precursor cells as a source for regeneration of tissues but also accessory cells that support angiogenesis and vasculogenesis by producing several growth factors. In this paper some of the phenotypical and functional activity of cells suitable for autologous transplantation for cartilage repair were analyzed. In vitro study