THE INHIBITION OF FIBROBLAST-POPULATED COLLAGEN LATTICE CONTRACTION BY HUMAN AMNIOTIC-FLUID - A CHRONOLOGICAL EXAMINATION

The effect of human amniotic fluid on fetal wound healing remains to be fully elucidated and may lead to the isolation of factors that could modulate adult wound healing. This, study uses an in vitro model of wound contraction, the fibroblast-populated collagen lattice, to examine the effects of chronologically sampled human amniotic fluid on contraction of lattices composed of either human adult or fetal fibroblasts. This chronology has not been reported previously. Human amniotic fluid was obtained in a sterile fashion via amniocentesis from 120 different women at different time points in gestation, ranging from 13 to 24 weeks. At each time point of gestation, three to five samples were individually examined in duplicate sets. Only fluid from pregnancies deemed normal by amniocentesis was included. Contaminated specimens were discarded. Using Bell's protocol, lattices were constructed of acid-soluble rat tail collagen, growth medium, and either human adult fibroblasts or human fetal fibroblasts. Lattices contained 20% v/v human amniotic fluid. In the control lattices, phosphate-buffered saline replaced amniotic fluid in equal volumes. Area was measured at 24-hour intervals, and all tests were run in duplicate for each specimen. The mean area at each interval was computed for each gestational week examined. Data were analyzed for significance with ANOVA and Dunnett's t test against control. In the adult fibroblast lattice series, there is a statistically significant inhibition of contraction at endpoint with amniotic fluid from 14 (532 +/- 28 mm2), 20 (539 +/- 20 mm2), 21 (639 +/- 27 mm2), and 22 weeks (554 +/- 36 mm2) in gestation when compared with control (367 +/- 55 mm2)(p < 0.05). In the fetal fibroblast lattice series, there is a significant inhibition of lattice contraction with amniotic fluid from 20 (477 +/- 10 mm2) and 21 weeks (549 +/- 18 mm2) when compared with control (366 +/- 24 mm2)(p < 0.05). In both series, 21-week-old fluid produces the greatest inhibition of contraction, and significant inhibition of lattice contraction is evident by 24 hours. Fetal fibroblasts characteristically show a heightened ability to contract lattices in the presence of amniotic fluid when compared with adult fibroblasts. This study shows that human amniotic fluid of specific gestational age inhibits the ability of fibroblasts to organize a collagen matrix. Such findings corroborate earlier findings in some but not all animal models and demonstrate that human amniotic fluid has the capacity to modulate fetal wound repair.