Primary Cilia in Chondrogenic Differentiation of Equine Bone Marrow Mesenchymal Stem Cells: Ultrastructural Study

Locomotor system disorders in equine species, such as tendon lesions, osteoarthritis, or ligament injuries, are some of the most frequent causes of dramatic reduction in horse performance. Traditional therapies are aimed at the inflammatory process and pain, but they do not regenerate normal tendon or ligament matrix and do not reduce re-injured rates. Mesenchymal stem cells have started to use as therapeutic option to repair these injured tissues. Most studies have focused on their isolation, in vitro culture and phenotyping. However, mesenchymal stem cell ultrastructure has been disregarded in the last years. We investigate the ultrastructural characteristics of these cells once differentiated into chondrocytes. Ultrastructural analysis was conducted on suspension cultures of differentiated chondrocytes from bone marrow mesenchymal stem cells by means of transmission electron microscopy. The morphologic characteristics of these cells, their ability to produce the extracellular matrix, and the presence of a single cilium could be indicative of the mesenchymal cells differentiation into chondrocyte phenotype. This study provides essential data to evaluate the degree of suitable phenotypic stability, for these cells can be used with repair purposes.