Effects of antimetabolite induced cellular growth arrest on fibroblast-fibroblast interactions

The use of single five-minute applications of antimetabolites during glaucoma filtration surgery has significantly reduced the occurrence of post-operative scarring and bleb failure. However, surgery for some patients is still unsuccessful, despite the use of antiproliferative agents, due to formation of scar tissue at the drainage site. It is not known if cells growth arrested in the treated area with a single application of antimetabolites influence the activity of adjacent non-treated cells. We hypothesise that the activity of non-treated cells recruited to the wound site may be involved in post-operative scarring. The aim of this study was to investigate the effects of antimetabolite induced cellular growth arrest on cell-cell interactions using in vitro techniques.Tenon's capsule fibroblast cultures were growth arrested by exposure for 5 minutes to mitomycin-C (0.001, 0.01 and 0.1 mg ml-1), 5-fluorouracil (0.25, 2.5 and 25 mg ml-1) or phosphate buffered saline (PBS). Following a period of serum-starvation, conditioned media (CM) were subsequently collected from the cells at intervals up to 29 days post-treatment. Correction for cell number was made prior to supplementation of serum-free medium with CM. CM were assessed for ability to support or inhibit normal non-treated fibroblast proliferation, migration and collagen contraction. Conditioned media collected from cells growth arrested with MMC or 5FU stimulated normal fibroblast proliferation, migration and collagen contraction in excess of non-conditioned serum-free medium. Peaks of fibroblast activity in CM differed according to which drug and concentration had originally been given to the treated cells. This study has demonstrated that CM collected from fibroblasts treated for 5 minutes with a range of concentrations of antimetabolites can differentially influence normal non-treated fibroblast activity. This in vitro data suggests that despite entering growth arrest, fibroblasts may still influence the behaviour of other cells via soluble mediators. They may have implications in the clinical setting, in that it may not be sufficient to suppress proliferation alone to prevent fibroblast behaviour associated with scarring after glaucoma filtration surgery.