A COMPARISON OF THE EFFECT OF EPIDERMAL GROWTH-FACTOR, PLATELET-DERIVED GROWTH-FACTOR, AND FIBROBLAST GROWTH-FACTOR ON RAT PERIODONTAL-LIGAMENT FIBROBLAST-LIKE CELLS DNA-SYNTHESIS AND MORPHOLOGY

AN ENHANCED FORMATION OF BONE, DENTIN, AND COLLAGEN FIBERS in periodon tal wounds after application of polypeptide growth factors has recentl y been reported. However, the complex environment in vivo makes it imp ossible to determine the specific effects of growth factors; on variou s cells involved in the wound-healing process. We have therefore inves tigated the mitogenic and morphogenic effects of recombinant epidermal growth factor (rEGF), natural platelet-derived growth factor (nPDGF), and natural fibroblast growth factor (nFGF) on periodontal ligament f ibroblast-like cells. A cell line was established from rat PDL tissue. The cell line was characterized according to morphology, growth patte rn, cytoskeletal proteins, and growth kinetics. The mitogenic effect o f growth factors was assessed by incorporation of [H-3]thymidine in th e cellular DNA for 4 hours. Differences between groups of observations were assessed by the Student t-test. The morphogenic effects of growt h factors were described with respect to growth pattern, cell orientat ion, and cell and nucleus form after a random photographic recording. The fibroblast-like cell type and the non-transformed phenotype of the cell line have been identified by the presence of parameters consider ed to be characteristic of a normal fibroblast-like cell line. The mor phogenic analysis of both experimental and control cultures showed a m onolayer of adherent cells with spindle or stellate morphology, a rand om alignment and round or elongated nuclei. Incorporation of [H-3]-thy midine was increased in a dose-dependent manner by all growth factors. Maximal effect on the DNA synthesis was: rEGF, 131%; nPDGF, 274%; and nFGF, 182%. The results show that growth factors in high concentratio ns have no dramatic effects on the morphology of PDL fibroblast-like c ells. However, variation in the mitogenic potency of the growth factor s should be considered when these growth factors are used in periodont al treatments in the future.