LONG-TERM GROWTH ARREST OF HUMAN TENONS FIBROBLASTS FOLLOWING SINGLE APPLICATIONS OF BETA-RADIATION

Aims/background-Antimetabolites are increasingly used to manipulate th e healing response after filtration surgery, but problems with thin cy stic blebs have been encountered with the Liquid agents commonly used such as 5-fluorouracil and mitomycin C. beta Radiation appears to be a useful adjuvant treatment for preventing scarring after trabeculectom y, resulting in diffuse rather than cystic bleb formation, but much of the basic cell biology of the ocular fibroblast response to beta radi ation remains unclear. The effects of beta radiation on ocular fibrobl ast proliferation and cell cycling mere investigated to determine the nature and duration of these effects on these cells. Methods-In vitro cell culture techniques were used to investigate fibroblast proliferat ion. Cell viability was studied using trypan blue dye exclusion. The e ffect of radiation on cell cycling was investigated using bromodeoxyur idine uptake. p53 expression was demonstrated using immunocytochemistr y. Results-beta Radiation inhibited fibroblast proliferation in a dose dependent manner. Early cell death was not a prominent feature, but i rradiated fibroblasts demonstrated a rapid onset and sustained period of growth arrest. p53 expression was found to be increased in irradiat ed cells. Conclusions-Single doses of beta radiation significantly inh ibit Tenon's capsule fibroblast proliferation in vitro over a 28 day p eriod. This inhibition is the result of a rapid onset and sustained pe riod of growth arrest in irradiated cells. Irradiated fibroblasts show an increase in p53 expression, a nuclear phosphoprotein which has bee n associated with control of the cell cycle. Single applications of be ta radiation may be an effective treatment for the prevention of bleb failure as a result of prolonged growth arrest of Tenon's capsule fibr oblasts.