Injuries of articular cartilage are one of the major problems in our population with immense economical cost for the society. Surgical treatment options have been established but none may provide a sufficient outcome and a complete regeneration of injured cartilage. The hormone sensitivity of cartilage is predominately accepted for the onset of degeneration (i.e. osteoarthritis) after menopause. Based on these findings, we hypothesise that also regeneration after cartilage injury is modulated by sex hormones. Direct hormone effects on chondrocytic cells, which may be mediated via sex hormone receptors, protein kinase dependent pathways or production of anabolic factors (i.e. growth factors), and indirect effects via modulation of the immune response might be involved in the hormone dependent regeneration process. Chondrogenesis of mesenchymal stem cells is regulated by sex hormones as can be observed under physiological conditions in the growth plate during adolescence. Therefore, we hypothesise that we can improve chondrogenic differentiation of mesenchymal stem cells and simultaneously prevent the onset of cartilage hypertrophy and bone formation under the influence of sex hormones. This will lead to a new sex hormone dependent stem cell based tissue engineering approach for regeneration of cartilage injuries.
