Pluripotent stem cell differentiation to osteogenic and chondrogenic precursor cells

Osteo/chondrogenic progenitor (OCP) cells were derived from pluripotent stem cells (PSC) including embryonic and induced pluripotent stem cells. The PSC were induced to undergo an epithelial to mesenchymal transition resulting in OCP cells that had unique developmental characteristics. After transitioning to a mesenchymal phenotype, the OCP were highly proliferate as an adherent cell monolayer and maintained karyotype stability for more than 75 population doublings. OCP cells readily differentiated in vitro into osteogenic and chondrogenic subtypes. In contrast, tissue sourced adult mesenchymal stem cells (MSC) have broad potential but present potential drawbacks, including: 1) variability in starting population; 2) limited lifespan; 3) heterogeneous multilineage differentiation potential. These issues are overcome by PSC derived OCP cells which do not require manual selection or sorting to produce a unique cell type. However, the OCP cells unexpectedly lacked adipogenesis potential following exposure to adipogenic differentiation culture conditions. The developmental mechanism(s) responsible for OCP cell adipogenesis deficiency is largely unknown. These characteristics may be related to their ontologically nai've state of development compared to adult sourced MSC. We showed that OCP cells are epigenetically distinct from adult MSC given promoters for genes related to adipogenesis in multiple OCP cells were highly methylated. Using bisulfite sequencing analysis of CpG methylation, we found that the promoters of 3 adipogenic-associated genes, LPL, FABP4 and PPARG2, were highly methylated in OCP cells, but not in adult MSC, suggesting that the methylation in OCP cells can differ from some adult sourced MSC. The OCP cells may be used in a variety of research applications, such as studying bone and cartilage formation, and further exploration of epigenetic factors that prevent adipose cell formation/differentiation