Effects of 5-fluorouracil on proliferating fibroblasts in vivo

5-Fluorouracil (5-FU) is a potent inhibitor of the proliferation of fibroblasts, the main cell mediators of scar formation. The mechanism of the toxic effect of 5-FU on cancer cells is well known but unclear in nonmalignant cells. The histopathological effects of 5-FU on proliferating fibroblasts in vivo, 2 and 4 weeks after drug injection, are demonstrated here. An insertion of homologous fibroblasts into rabbits' vitreous followed by one injection of 1 mg 5-FU causes intracytoplasmic accumulation of vacuoles, morphological changes and inhibition of collagen deposition in the matrix.