Long term growth arrest of human Tenon's fibroblasts following single applications of beta radiation

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Abstract
AIMS/BACKGROUND Antimetabolites are increasingly used to manipulate the healing response after filtration surgery, but problems with thin cystic blebs have been encountered with the liquid agents commonly used such as 5-fluorouracil and mitomycin C. β Radiation appears to be a useful adjuvant treatment for preventing scarring after trabeculectomy, resulting in diffuse rather than cystic bleb formation, but much of the basic cell biology of the ocular fibroblast response to β radiation remains unclear. The effects of β radiation on ocular fibroblast proliferation and cell cycling were investigated to determine the nature and duration of these effects on these cells. METHODS In vitro cell culture techniques were used to investigate fibroblast proliferation. Cell viability was studied using trypan blue dye exclusion. The effect of radiation on cell cycling was investigated using bromodeoxyuridine uptake. p53 expression was demonstrated using immunocytochemistry . RESULTS β Radiation inhibited fibroblast proliferation in a dose dependent manner. Early cell death was not a prominent feature, but irradiated fibroblasts demonstrated a rapid onset and sustained period of growth arrest. p53 expression was found to be increased in irradiated cells. CONCLUSIONS Single doses of β radiation significantly inhibit Tenon’s capsule fibroblast proliferation in vitro over a 28 day period. This inhibition is the result of a rapid onset and sustained period of growth arrest in irradiated cells. Irradiated fibroblasts show an increase in p53 expression, a nuclear phosphoprotein which has been associated with control of the cell cycle. Single applications of β radiation may be an effective treatment for the prevention of bleb failure as a result of prolonged growth arrest of Tenon’s capsule fibroblasts.