Isolation and culture of corneal cells and their interactions with dissociated trigeminal neurons.

The three cell types of rabbit cornea (epithelium, stromal fibroblasts and endothelium) were isolated by an improved method using both microdissection and selective enzyme treatment. This technique reproducibly resulted in an almost total recovery of each cell type from a given cornea. When maintained in culture, the three cell types showed different morphologic characteristics, each resembling the in vivo counterpart. The epithelial culture consisted of both attached and floating cells. The attached cells located at the marginal area of a colony were irregular in shape and possessed pseudopodia, while those in the confluent area were polygonal. Floating cells were typically vacuolated, curve-shaped and joined in groups of 2-4 cells as a spherical body enclosing a lucent interior. Comparison of mitotic rates, ultrastructure, keratin levels and other cytologic evidence suggested that the attached cells may correspond to the basal cells and less differentiated wing cells, while the floating cells may be analogous to the more differentiated wing cells and superficial cells. Neurons dissociated from neonatal rabbit trigeminal (Gasserian) ganglia were plated into multiwells partially covered with a given corneal cell type. The percentages of viable and neurite-bearing neurons were evaluated on the first three days. When neurons were grown in contact with each of the corneal cell types, neurites were extended in every case. However, when neurons were not in contact with the corneal cells in the coculture, only epithelial cells permitted neurite outgrowth. The data suggested two types of cellular interactions between corneal cells and sensory neurons, one of which may be the specific release of a neuronotrophic factor by epithelial cells. This culture system represents the first step towards developing an in vitro model for studying various cornea-trigeminal interactions.