Figure 2.

Reported cell delivery methods to restore AuN function. (A) Reported cell delivery methods in Table 1 are shown with arrows in the upper panel. Dark shaded parts of each arrow indicate intracochlear or intraneural portions of each route. Arrows show each route conceptually and do not trace each anatomical route precisely. The dotted rectangle is enlarged to illustrate intracochlear structures in detail. (B) Surface transplantation of DCs on degenerated AuN. DCs transplanted onto the surface of degenerated AuN autonomously enter the nerve, differentiate (*) and form functional synapses with HCs and CNs (#). In degenerated AuN, the AO and SC columns form a continuous, “naturally occurring autologous cell bridge”, the AO–SC complex (a part is shown here), which acts as an anatomical scaffold for DC migration to connect between the PNS and the CNS (see the text). Note regenerating axons run parallel with the AO–SC complex. Studies using systemic delivery of donor cells are not shown here. AO, astrocyte outgrowth; AuN, auditory nerve; CNS, central nervous system; CN, cochlear nucleus cell; CPA, cerebellopontine angle; DC, donor cells; HC, hair cell; IAC, internal auditory canal; IAM, internal auditory meatus; IHC, inner hair cell; OHC, outer hair cell; MLI, membranous labyrinth injured; MLP, membranous labyrinth preserved; PNS, peripheral nervous system; RC, Rosenthal’s canal; ScM, the scala media; SC, Schwann cell; ScT, the scala tympani; ScV, the scala vestibuli; SuC, supporting cell; TZ, the transitional zone.