Using the conditions that were developed for mouse
ES cells, it should be possible to generate hair cells from
human ES cells. Although the use of human ES cells for
differentiation into a variety of cell types is at an early
stage, several lines have been shown to differentiate into
neurons after transplantation into the brain [63]. ES cells
can be engineered in vitro by introducing genes into cell
lines, before transplantation into animal models to improve
engraftment. As with any stem cells, the potential for tumor
growth needs to be observed in these animal models