The Center for Alternatives to Animal Testing is an academic center affiliated with the Division of Toxicological Sciences in the Department of Environmental Health Sciences of the Johns Hopkins University Bloomberg School of Public Health.

 

Johns Hopkins School of Public Health

Research Grants 1998-1999

Ocular Epithelial Organotypic Cultures

James D. Zieske, PhD
Schepens Eye Research Institute, Boston, Massachusetts

The anterior surface of the eye is covered by contiguous but morphologically distinguishable epithelia overlying the cornea, limbus, and conjuctiva. These epithelia, along with the associated tear film, form the first line of defense for the eye by providing a barrier to pathogen entrance as well as preventing the entrance of toxic and/or irritating chemicals and compounds. This barrier function is dependent on the formation of specialized junctions (termed tight junctions), which prevent the passage of fluids between cells. Zieske and colleagues have developed an organotypic culture of rabbit cornea. In this model, rabbit corneal epithelial cells were cultured over rabbit stroma fibroblasts in a collagen matrix with an underlying layer of immortalized mouse corneal endothelial cells. This culture model greatly resembled a rabbit cornea, including the formation of a barrier function. Zieske proposes to develop a similar model using human tissues obtained from eye-bank eyes. It is his assumption that for a compound to be damaging to the eye, it must pass directly through the epithelial cell or through a pathway between cells, which is normally sealed by tight junctions. Thus, a compound that disrupts tight junctions has a greater potential to cause damage than one that does not. Zieske and colleagues also assume that a compound that causes long-term problems must affect the dividing cell populations, which will cause alterations in epithelial differentiation. The models they plan to develop have the potential to test both short- and long-term effects of chemicals and compounds. These models have great potential for in vitro safety testing of consumer products on cultured human tissues, thereby reducing the need for live animal testing.