Therefore, cellular regeneration within the cochlear
spiral might restore function without following the exact
developmental program that controls the embryogenesis of
the organ of Corti. Furthermore, to replace the correct
anatomical arrangement, the progenitor cells would have
to selectively replant the vacant basilar membrane or
selectively replace the undifferentiated epithelial-cell
layer that appears in damaged cochleae in lieu of the
organ of Corti. These new cells need to form a sensory
epithelium that is capable of attracting the remaining
afferent spiral ganglion nerve fibers and of forming a
functional synaptic contact with those fibers. It is plausible
that such new hair cells will be readily innervated, because
the delivery of the gene encoding atonal homologue 1 to the
inner ear [49–51] resulted in new hair cells that were
approached by nerve fibers [49]. It remains to be determined
whether newly generated hair cells, which are often
located in a micromechanically less advantageous location
in the cochlea, can improve hearing or whether directed
gene delivery to the damaged organ of Corti leads to local
re-occurrence of hair cells