Nature Methods

A new technique for human embryonic stem cell (hESC) culture that reduces the use of animal-derived compounds, making them potentially safer and more reliable for biomedical applications is reported in the March issue of Nature Methods.

hESCs have the potential to form any other cell type in the body, a process called differentiation; but this flexibility comes at a price, and these cells are notoriously difficult to cultivate so that they maintain their potential. Current techniques involve growing them atop mouse-derived "feeder" cells, or in an environment that has been saturated with compounds produced by such cells.

This is problematic, as it raises the risk of exposing hESCs to animal-borne pathogens. Additionally, recently published findings (Martin et al., Nature Medicine 11, 228-232; 2005) demonstrated that hESCs could take up and present a highly immunoreactive mouse cell-derived molecule during culture, raising a serious risk of host immune response after transplantation.

An animal product-free stem cell culture system would be ideal, and although this goal is still over the horizon, James Thomson, Ren-He Xu and their colleagues present an important step in this direction, demonstrating successful hESC culture without feeder cell contribution.