TGFB3 and osteoarthritis: To resemble more closely the clinical situation, the aim of the current study was to evaluate the effect of human synovial fluid from normal, rheumatoid arthritis and osteoarthritis donors on the chondrogenic differentiation of human subchondral cortico-spongious progenitor cells, without any external chondrogenic stimulus by recombinant growth factor TGFB3.