Abstract
Purpose: :
The lens consists of epithelial cells and their differentiated fiber cell derivatives. A third population, called Myo/Nog cells, was discovered in the chick embryo lens by their expression of MyoD mRNA, noggin and the G8 antigen. The release of noggin by Myo/Nog cells is critical for normal eye development. In addition, Myo/Nog cells respond to wounding by migrating to the leading edge of the lens epithelium and maturing into myofibroblast-like cells that express alpha smooth muscle actin (α-sma) and vimentin. The purpose of this study was to examine the human lens for Myo/Nog cells and determine whether they can be depleted by immunotherapy.
Methods: :
Donor human eyes were obtained from the National Disease Research Interchange. Anterior lens tissue was removed during cataract surgery by capsulorhexis. Explants and tissue sections were fluorescently labeled with dendrimers to MyoD mRNA and antibodies to the G8 antigen, noggin and α-sma. Anterior lens explants were incubated with the G8 monoclonal antibody and complement. Five hours after treatment, explants were fixed and stained with a fluorescent secondary antibody and TUNEL reagents.
Results: :
Small numbers of cells expressing MyoD mRNA, noggin protein and the G8 antigen were present among the epithelial cells in the anterior and equatorial regions of the human lens. Approximately two percent of the cells in anterior lens tissue isolated by capsulorhexis were stained for noggin and G8. Most Myo/Nog cells were randomly distributed between the lens epithelial cells; however, some were organized around the edges of circular, cell free vacuoles. The G8-positive cells lining the vacuoles expressed α-sma. A few of the vacuoles contained a wrinkle in the capsule. Incubation of anterior lens tissue with the G8 antibody and complement lysed 85-100% of the Myo/Nog cells.
Conclusions: :
Myo/Nog cells are present in the human lens. Experiments with explants of anterior lens tissue indicate that the G8 antibody can be used to kill Myo/Nog cells. More posterior regions of the lens epithelium also contain Myo/Nog cells, and therefore, depleting them during cataract surgery may reduce the incidence of lens reopacification caused by myofibroblast-like cells.
Keywords: clinical research methodology • pathology: human • cataract