Fetal rat amniotic fluid: Transforming growth factor beta and fibroblast collagen lattice contraction

Background. In several mammalian animal models, early-gestational-age fetal wounds heal without scar, but wounds of late gestational age heal with sca r. This change in wound healing phenotype can be a result of both intrinsic (i.e., cellular characteristics) and extrinsic (i.e., environmental) facto rs. Our question was: Does amniotic fluid (AF) influence the change from sc arless to scar-forming repair in the rat? Methods. Rat AF was investigated for its modulation of fibroblast-populated collagen lattice (FPCL) contraction and morphological changes of adult fib roblasts. AF was also assayed for transforming growth factor beta (TGF-beta ) levels. Adult rat dermal fibroblasts in monolayer and incorporated into F PCLs were incubated with AF additions from gestational age 14,16,18, and 21 days at 10% (v/v). Results. Day 14 AF significantly stimulated FPCL contraction, but AF of 16, 18, and 21 days inhibited FPCL contraction. Fluorescence histology identif ied microtubules and microfilaments in AF treated adult rat dermal fibrobla sts. The staining pattern of microtubules in Day 14 AF-treated fibroblasts showed denser structures at the cell center. Cells incubated with Day 16 or IS AF showed fine peripheral microtubules. A mink lung epithelial cell bio assay was used to analyze concentrations of TGF-beta in AF. TGF-beta levels were greatly elevated in Day 14 AF, but were relatively low in Day 16, IS and 21 AF. The inhibitor of FPCL contraction from AF of Days 16, 18, and 21 was not identified. Conclusion. It is proposed that the robust expression of TGF-beta or cytosk eletal changes induced by Day 14 AF contributes to enhanced FPCL contractio n. (C) 2001 Academic Press.