CYTOTOXIC EFFECTS OF FGF2-SAPORIN ON BOVINE EPITHELIAL LENS CELLS IN-VITRO

Purpose. To test the ability of two preparations of FGF2-saporin, eith er FGF2 chemically conjugated to saporin (FGF2-SAP) or genetically eng ineered FGF2-saporin (rFGF2-SAP) to inhibit the growth of bovine epith elial lens (BEL) cells in vitro when in solution and when immobilized on heparin surface-modified (HSM) polymethylmethacrylate (PMMA) intrao cular lenses (IOLs). Method. Bovine epithelial lens cells were incubat ed with various concentrations of FGF2-saporin for as long as 4 days. The number of surviving cells was determined by counting the number of nuclei. Because FGF2 binds to heparin, FGF2-saporin was incubated wit h HSM PMMA IOLs; excess toxin was washed off, and the BEL cells were g rown on the FGF2-saporin-treated IOLs (HSM and non-HSM) for 4 days. Ce ll density was determined by image analysis. Results. Both FGF2-SAP an d rFGF2-SAP were highly cytotoxic (nM range), with rFGF2-SAP 10 times less active than FGF2-SAP. FGF2-saporin bound to the surface of HSM IO Ls and eluted by 2M NaCl retained its activity. Toxin bound to HSM IOL s killed more than 90% of the BEL cells placed on the IOL surface with in 4 days. The ability of FGF2-saporin to prevent the growth of cells on the IOL surface was strictly dependent on the presence of heparin o n the IOL. Conclusions, FGF2-saporin is bound to HSM PMMA IOLs and pre vents the growth of epithelial cells on the surface of the lens.