Proteomic characterisation of the conditioned media produced by the visceral endoderm-like cell lines HepG2 and End2: Towards a defined medium for the osteogenic/chondrogenic differentiation of embryonic stem cells.

Imperial College London, Chemical Engineering, London, United Kingdom; yunyi.kang04@imperial.ac.uk.

Visceral endoderm is an extraembryonic cell layer formed prior to gastrulation that secretes critical factors involved in embryonic development with inductive effects on embryonic stem cell (ESC) differentiation. We utilised the conditioned media (CM) from the visceral endoderm-like cell lines, HepG2 and END2, to enhance lineage-specific differentiation of murine ESCs (mESCS) towards the osteogenic lineage. Previously, we have demonstrated that use of the HepG2-CM resulted in the efficient osteogenic/chondrogenic differentiation of mESCs without embryoid body (EB) formation. Herein we demonstrate, for the first time, the osteogenic-inducing activity of END2-CM suggesting a potential shared protein profile between HepG2- and END2-CM. In order to identify the active factors in the conditioned media, proteomic analysis using differential gel electrophoresis coupled with matrix-assisted laser desorption/ionization was performed on the two CM, resulting in 6 proteins being established to be present in both conditioned media, including ones that may function on the epithelial-mesenchymal transition. Our results represent the first study on the visceral endoderm-like cell line secretome and provide information on visceral endoderm proteins identifying possible candidate proteins to be used for mesoderm-specific osteogenic differentiation.

PMID: 18393639 [PubMed - as supplied by publisher]