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 scar. This change in wound healing phenotype can be a result of both intrinsic (i.e., cellular characteristics) and extrinsic (i.e., environmental) factors. Our question was: Does amniotic fluid (AF) influence the change from scarless 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 fibroblasts. AF was also assayed for transforming growth factor beta (TGF-beta) levels. Adult rat dermal fibroblasts in monolayer and incorporated into FPCLs 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 identified microtubules and microfilaments in AF treated adult rat dermal fibroblasts. The staining pattern of microtubules in Day 14 AF-treated fibroblasts showed denser structures at the cell center. Cells incubated with Day 16 or 18 AF showed fine peripheral microtubules. A mink lung epithelial cell bioassay 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, 18 and 21 AF. The inhibitor of FPCL contraction from AF of Days 16, 18, and 21 was not identified.


CONCLUSIONS
It is proposed that the robust expression of TGF-beta or cytoskeletal changes induced by Day 14 AF contributes to enhanced FPCL contraction.
Levinson
H
H
Department of Surgery, Laboratory of Developmental Biology and Repair, New York University Medical Center, New York, NY, USA.
Peled
Z
Z
Liu
W
W
Longaker
M T
MT
Allison
G M
GM
Ehrlich
H P
HP
D008841:Actin Cytoskeleton / Q000502:physiology; D000367:Age Factors; D000653:Amniotic Fluid / Q000737:chemistry*; D000818:Animals; D002478:Cells, Cultured; D002921:Cicatrix / Q000378:metabolism; D003094:Collagen / Q000378:metabolism*; D020405:Dermis / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology; D005865:Gestational Age; D008870:Microtubules / Q000502:physiology; D008907:Mink; D051381:Rats; D017207:Rats, Sprague-Dawley; D020545:Respiratory Mucosa / Q000166:cytology; D016212:Transforming Growth Factor beta / Q000032:analysis*; D014945:Wound Healing / Q000502:physiology*
D016212:Transforming Growth Factor beta; D003094:Collagen