ABSTRACT
The work of Friedenstein and Owen M.E. on the osteogenic potential of bone marrow cells is widely acknowledged as the foundation of the present research on adult stem cells. This chapter focuses on mesoderm lineages. It describes osteogenic, adipogenic, and chondrogenic differentiation in human mesenchymal stem cell cultures (hMSC) represent standard in vitro assays and well-established protocols. Chondrogenic pellets are prepared in micromass cultures maintained in serum-free conditions, in the presence of dexamethasone and TGFbeta. Chondrogenic markers such as collagen II, collagen X, aggrecan, syndecan-1 are looked for after 2-3 weeks of treatment and Saffranin-O staining of pellet sections provides visual assessment of differentiation. A pragmatic hypothesis is that upon appropriate treatment in vitro, human embryonic stem cell cultures could be stimulated to give rise to a more mature cell population with hMSC characteristics. Such a protocol would contribute valuable fundamental scientific information, as well as an alternative solution to hMSC expansion variability by providing a robust supply of cells.
