Derivation, culture, and in vivo developmental capacity of embryonic cell lines from rat blastocysts.

Embryonic stem (ES) cells have been used extensively for site-specific gene targeting in the mouse. The resulting knock-out and knock-in mouse models generated so far have demonstrated their usefulness in biomedical research. However, for many diseases and fields of study, the rat still represents a superior model. The derivation and culture of germline-competent ES cells in the rat would allow the application of site-specific gene targeting technologies to this species of indisputable importance to biomedical research. We have recently shown the derivation, culture, and for the first time, in vivo contribution of rat ES-like cells to developing tissues. This represents an important step forward in making gene targeting technologies available to the rat research community, via development of rat ES cells. Here, we describe the materials, methods and techniques that have been used to obtain rat blastocysts, derive and culture embryonic cell lines from these, and assess the developmental capacity of the cells in vivo.