Feeder layers embryonic stem cells

Irradiated embryonic fibroblast feeder cell layer to be used for growing the embryonic stem cell line G418 resistant embryonic fibroblast cells are derived from embryos that carry a targeted disruption such as the 3-2 microglobulin gene (9). 

Approximately 105 transfected embryonic stem cells are selected. Transfected embryonic stem cells are grown on layers of y-irradiated embryonic fibroblast cells. Transfected cells are plated on G-418 resistant embryonic fibroblasts feeder layers and selected in G-418 and after 36 h they are selected in Fialuridine (FIAU) or gancyclovir. 

By culturing specific cells from cloned embryos, scientists can make embryonic stem cell (ESC) cultures. During mammalian development, two distinct cell populations form after the first few days of embryonic development. The trophoblast, or the flattened, outer layer of cells, will eventually form the placenta and its associated structures. The inner cell mass (IGM) is the round, inner clump of cells that develop to form the embryo proper and a few structures associated with the placenta. If IGM cells are isolated and cultured on feeder cells, a layer of nondividing skin cells that secrete a cocktail of growth-promoting chemicals, the IGM cells will grow and spread over the surface of the culture dish. Such a culture is an embryonic stem cell culture, and these cells are pluripotent, which means that they can differentiate into any cell type in the adult body. 

In fact the transition from bench to market of combination products is often hindered by a series of scientific and economic issues. Both the determination of the ideal cell type and the ideal biomaterial for the specific application can be problematic. Often, the use of autologous differentiated cells would be the best solution, but their use may not be feasible because of limitation on isolation and expansion. Moreover, the use of autologous cells also can introduce infections risks deriving from the use of xenogenic factors or animal feeder layers in culture. Hopefully, adult and embryonic stem cells may provide alternative solutions. Also the determination of the most suitable biomaterial for the specific application is a challenge. Most of the currently available synthetic materials are subjected to a foreign body reaction that can lead to serious complications when implanted in the human body. The use of natural scaffolds circumvents this problem, but it introduces other drawbacks such as inappropriate mechanical properties. Smart combinations of synthetic scaffolds modified with natural... 

Beattie, G. M., Lopez, A. D., Bucay, N. et al. 2005. Activin a maintains pluripotency of human embryonic stem cells in the absence of feeder layers. Stem Cells 23(4) 489-95. 

M. Amit, C. Shariki, V. Margulets, and J. Itskovitz-Eldor, Feeder layer- and serum-free culture of human embryonic stem cells, Biol Reprod., 70 (3) 837-845, Mar. 2004. 

---