Effect of FGF-2 mutants on new vessel formation in a placental explant model. The growth of vessels from human placental vessel fragments cultured in a fibrin gel with Medium 199 and 10% FBS for 18 days, in the presence or absence of FGF-2 or FGF-2 mutants is shown. (A) Control; (B) wtFGF-2; (C) fibrinogen nonbinding mutant (2212); (D) fibrinogen-binding mutant (221^*2). Right panel: New vessel growth was quantified using image analysis software. Both wtFGF-2 and 221^*2 supported significantly increased vessel growth over medium alone (P < .05 for both). The results are the mean ± SE of 3 separate experiments.