Living isolated cells from inner ear vessels: a new approach for studying the regulation of cochlear microcirculation and vascular permeability.

The spiral modiolar artery with its proximal branches and the microvessels in the spiral ligament and the stria vascularis were microdissected from the guinea pig cochlea. After incubation with proteolytic and collagenolytic enzymes the mixed cell suspension was fractionated by gradient centrifugation. The cells migrated according to their buoyant densities into the fractions of 1.04 g/ml (endothelial cells), 1.06 g/ml (vascular smooth muscle cells obtained from the spiral modiolar artery; strial pericytes) and 1.08 g/ml (pericytes obtained from the spiral ligament). To test for viability cells were loaded with a fluorescent vital stain (BCECF-AM); for identification, cell-specific stains were used. Identity of endothelial cells (ECs) was confirmed using acetylated low density lipoprotein fluorescently labeled with dioctadecyl-tetramethyl-indocarbocyanine perchlorate (DiI-Ac-LDL). Pericytes were identified immunofluorescently using the method according to Nayak et al. (1988). Vascular smooth muscle cells were stained for F-actin with rhodamin-phalloidin. This in vitro technique may open new approaches to study local factors involved in microcirculation and vessel permeability of various cochlear vascular beds.