Hair cell regeneration in the inner ear: a review

Abstract

Hair cell regeneration has been shown to occur in the inner ear of mammals. Specifically, it has been demonstrated in the vestibular system and not the organ of Corti. Recent evidence suggests that the degree of the regenerative response may be augmented pharmacologically. This review discusses the field of hair cell regeneration in fish, amphibians, birds and mammals, and the relationship of regeneration to functional recovery

Balanced levels of Espin are critical for stereociliary growth and length maintenance

“…A similar transformation of supporting cells into hair cells was described previously in birds and lizards, in which damaged hair cells are spontaneously replaced by new sensory cells that originate from surrounding supporting cells. Thus, hair cells and supporting cells may have common precursors [Walshe et al, 2003]. Our results suggest that expression of Espin in supporting cells could account for a significant fraction of the morphological transdifferentiation that accompanies the conversion of supporting cells to hair cells.…”

The use of zebrafish for assessing ototoxic and otoprotective agents

“…These conserved pathways in zebraWsh permit study of eVects of potential therapeutics, such as neurotrophic factors, antioxidants and antiapoptotic agents on hair cells loss. The production of hair cells and supporting cells in mammals is restricted to a short period during embryogenesis (reviewed in Walshe et al, 2003); in contrast, Wsh and amphibians can produce hair cells during both embryogenesis and postembryonic stages (Popper and Hoxter, 1984;Corwin, 1985). Although the hearing system is one of the most common sites for drug-induced toxicity, due to high cost, the hearing system is not routinely evaluated in pre-clinical testing.…”

A Review of Past and Present Hair Cell Regeneration Techniques

“…Fish use two systems, the inner ear and the lateral line, to detect sounds and vibrations, respectively, which allow them to experience their aquatic environment (Lowenstein, 1957;Schellart & Wubbels, 1998;Walshe, Walsh, & McConn, 2003). Because the bodies of fish are similar to the density of seawater, sound waves cause the entire fish to move with the water and the sound passes through their bodies (Lowenstein, 1957;Schellart & Wubbels, 1998;Walshe et al, 2003). The otoliths, the bones of the inner ear of the fish, are composed of calcium carbonate and differ in dimension and shape among the various species of fish (Northern & Downs, 2002).…”

“…The otoliths, the bones of the inner ear of the fish, are composed of calcium carbonate and differ in dimension and shape among the various species of fish (Northern & Downs, 2002). Regardless of the species, the otoliths are much denser and thus move slower than the rest of the fish (Lowenstein, 1957;Schellart & Wubbels, 1998;Walshe et al, 2003). The difference between the motion of the otoliths and the motion of the fish stimulates the cilia on the hair cells, which is interpreted as sound (Lowenstein, 1957;Schellart & Wubbels, 1998;Walshe et al, 2003) The lateral line system extends along the side of the fish's body and onto the head, which permits the fish to detect acoustic signals over a distance of one to two body lengths and at low frequencies (Lowenstein, 1957;Schellart & Wubbels, 1998).…”

“…Depending on the direction of the hair cells, the nerve impulses get either enhanced or depressed. Fish use this lateral line system to detect the relative motion between themselves and the surrounding water in order to identify their orientation in the water and to avoid collisions and predation (Lowenstein, 1957;Schellart & Wubbels, 1998;Walshe et al, 2003).…”