Epithelial adhesion complexes and organ culture of the human cornea

The effects of extended organ culture of human cornea on the structural int egrity, particularly adhesion complexes, of the epithelium were determined. Human corneas were placed in organ culture using an immersion method. The structure of the cornea prior to culture (0 h) and at 7, 14, and 18 days in culture was evaluated by staining with hematoxylin/eosin, and by ultrastru ctural analysis that included a morphometric study of the type and number o f adhesion complexes. Human corneas prepared immediately (0 h) and those in culture after 7 days showed similar structural organization and anatomical features. In contrast to 0 h specimens, the corneal epithelium at 14 days in culture exhibited signs of deterioration, with increases in cellular con traction. extracellular space, electron density of the cytoplasm, nuclear i nvaginations, and nucleoplasmic opacity, as well as aggregations of junctio nal complexes between cells. At 18 days in culture, the ocular surface epit helium was markedly reduced in thickness and consisted of no more than 2-3 cell layers: a distinct basal layer was not detected, and the morphology of the suprabasal and basal layers were similar. The basement membrane was di sorganized, and anchoring complexes composed of hemidesmosomes were often a bsent. The number and type of the anchoring complexes associated with the b asal epithelium and Bowman's membrane were comparable until 14 days of age, although the total number of hemidesmosomes per pm of epithelial plasmalem ma was subnormal. After 2 weeks in culture, there were 38-72% fewer anchori ng complexes and a decrease of 44% in the number of hemidesmosomes/mum of m embrane from samples prepared immediately and after 7 days in culture. Thes e results indicate that the structural integrity of human corneal epitheliu m in organ culture is compromised after 14 days in vitro using an immersion system of tissue culture. Thus, long-term use of cultures to define homeos tasis and wound healing of the ocular surface epithelium. which necessitate s normal architecture including anchoring complexes between epithelium and Bowman's membrane, may not be appropriate and requires careful monitoring b oth qualitatively and quantitatively at the electron microscopic level of r esolution. (C) 2001 Elsevier Science B.V. All rights reserved.