Mesenchymal stem cells are non-differentiated cells with a high capacity to differentiate into tissues of mesodermal origin and a high potential for use in immunomodulatory and regenerative therapy, e.g. osteoarthritis. This is a degenerative disease of the joints that begins with microscopic changes in cartilage that lead to its excessive wear and eventually to bone damage. In this work, we aimed to investigate the ability of mesenchymal stem cells to form cartilage under in vitro conditions. We obtained stem cells from samples that differed by the underlying pathology of the donor (with or without degenerative changes of the hip joint) and by the site of collection (sinovium samples from three sites in the hip joint and samples from trabecular bone tissue). Samples were collected from 15 patients at the Orthopaedic Clinic of the University Medical Centre Ljubljana. Primary cells were cultured under in vitro conditions in either hondrogenic or control medium, and the hondrogenic pellets formed were used to prepare stained slides, which were then examined under the microscope. The morphology of the pellets was evaluated using the Bern score, while their diameter was also measured. Using statistical analysis, we demonstrated the influence of growth medium on pellet morphology and the influence of collection site on pellet diameter, while pathology had no effect on either parameter. We hypothesise that the key to these results lies in the specific characteristics of the mesenchymal stem cells and their microenvironment, and in the relatively small number of samples. Therefore, we believe that a larger number of samples, as well as conditions more similar to those in vivo, are needed for a better evaluation of the cartilage-forming ability of mesenchymal stem cells.
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