Homologous Recombination in Human Embryonic Stem Cells

This chapter discusses the three genes whose overall targeting frequencies suggest that homologous recombination is a broadly applicable technique in human ES cells. The homologous recombination frequencies are roughly comparable to those observed for mouse ES cells and suggest that, although successful transfection strategies differ between human and mouse ES cells, homologous recombination itself may be similar. Homologous recombination in human ES cells will be important for studying gene function in vitro, and for lineage selection. It is a powerful approach for understanding the function of any human gene. For therapeutic applications in transplantation medicine, controlled modification of specific genes should be useful for purifying specific ES cell-derived, differentiated cell types from a mixed population, and for altering the antigenicity of ES cell derivatives. It should be possible to give cells new properties (such as viral resistance) to combat specific diseases. Homologous recombination in human ES cells might also be used for recently described approaches combining therapeutic cloning with gene therapy. Another good example of where human ES cells and homologous recombination will be useful is in understanding the function of the human heart. With homologous recombination, one could generate human ES cell lines bearing mutations or polymorphisms in specific ion channels, and use ES cell-derived cardiomyocytes to better understand the effects of the mutations on the physiology of the heart. A panel of ion channel polymorphisms should be extremely useful for screening drugs for toxic side effects on the heart prior to clinical trials. Homologous recombination in human ES cells would be useful for numerous in vitro models of human disease. © 2009