Hyaluronic Acid as a Molecular Filter and Friction-Reducing Lubricant in the Human Inner Ear

Abstract

Immunofiuorescence for hyaluronic acid occurred intracellularly in morphologically highly specialized areas in the adult human inner ear, for instance in the cuticular plates of all types of hair cells, at the apposition between outer hair cells and Deiter’s cell bodies and in the near-surface area of Hensen’s cells. The cytoskeletal organization in these regions is characterized by tightly packed filamentous proteins. Under physiological stimulus these regions undergo micromechanical change, either actively moving (force generation) or passively vibrating with changes in elasticity. Hyaluronic acid might therefore act as a friction-reducing molecular lubricant. In the lateral wall of the cochlea an accumulation of hyaluronic acid occurred in the loose connective tissue of the spiral ligament, in particular close to the stria vascularis. Due to its complex molecular network, hyaluronic acid offers considerable resistance to bulk flow of water and may exclude molecules. The basal cell region of the stria vascularis is thus given additional support to minimize (seal?) the stria vascularis towards all other areas except the endolymphatic space. Here, hyaluronic acid could act as a molecular filter.

Development and Characterization of a Topically Deliverable Prophylactic Against Oxidative Damage in Cochlear Cells

“…In most tissue types, HA is cellularly internalized via HA-specific receptor mediated processes (Misra et al, 2015). The main HA receptor responsible for internalization is Cluster of Differentiation 44 (CD44); however, currently there are very limited data available on the presence of CD44 or endogenous HA in cochlear structures (Vilstrup and Jensen, 1954;Friberg et al, 1989;Anniko and Arnold, 1995;Hertzano et al, 2010). A survey of the gEAR multi-omic database (Orvis et al, 2021) indicated that CD44 is expressed in murine cochlear structures at the mRNA level (Hertzano et al, 2010).…”

Hyaluronan up-regulation is linked to renal dysfunction and hearing loss induced by silver nanoparticles

“…In addition, a concomitant alteration in the basal cells was associated with the accumulation of matrix in age-related morphological change [41]. Hyaluronic acid is distributed as a tissue-specific manner and, predominantly, in the spiral ligament of the inner ear [42,43]. Bianchetti et al [44] demonstrated that fibrocytes synthesized and released proteoglycan and exerted in a positive dominance for hyaluronic acid synthase-2 mRNA expression.…”

Soft Cochlear Implantation: Rationale for the Surgical Approach

“…The safety of hyaluronic acid in the middle ear is well established. Animal studies have shown that transtympanic application does not cause hair cell death or measurable decline in hearing thresholds (Anniko & Arnold, 1995;Anniko, Hellstrom, & Laurent, 1987;Bjurstrom, Slepecky, & Angelborg, 1987;Engstrom, Bjurstrom, Jansson, Engstrom, & Angelborg, 1987;Martini et al, 1992). In contrast, intracochlear injection of hyaluronic acid resulted in permanent sensorineural hearing loss in rats (Roland, Magardino, Go, & Hillman, 1995).…”