Gene targeting in human pluripotent cells

Mouse embryonic stem cells (mESCs) have the ability to differentiate into any cell type and can generate chimeric mice when transplanted into a host blastocyst. This remarkable potential, together with the development of robust gene targeting strategies in mESCs, were essential for establishing the mouse as the most widely used model organism in biomedical research. Recent advances have allowed the isolation of human embryonic stem cells and the derivation of induced pluripotent stem cells. Genetic tools similar to those proven routine in the mouse system are needed to realize the full potential of human pluripotent cells as disease models and putative therapeutics. Gene targeting in human cells, however, has proven to be more difficult, more time-consuming, and less robust than in mESCs. In this chapter, we discuss the strategies that have been used to allow specific genetic modifications in human pluripotent cells. We focus on the novel application of custom-engineered zinc-finger nucleases for gene targeting, which has promise to become a robust tool for efficient genetic manipulation of human pluripotent cells.