Matrix metalloproteinases-2 and -9 and their endogenous tissue inhibitors in tissue remodeling after sealing of the fetal membranes in a sheep model of fetoscopic surgery.
OBJECTIVE
We studied collagen plugging of the fetoscopic access site in an in vivo fetal lamb model for fetoscopic surgery and possible role for matrix metalloproteinase (MMP)-2 and -9 and tissue inhibitors (TIMPs).


METHODS
Eight ewes had fetoscopic balloon occlusion of the trachea as an experimental treatment for congenital diaphragmatic hernia between days 88 and 99 of gestation (term 145 days) with sampling of amniotic, allantoic, and tracheal fluid. Nonoperated cotwins were used as controls. The fetoscopy port was closed using a collagen plug. Ten days (range 9-12) later, fluids were sampled and plug sites collected for histologic analysis. Activity of MMP-2 (72 kDa, gelatinase A) and MMP-9 (92 kDa, gelatinase B) was determined in the fluids by zymography and secretion of TIMPs (27-30 kDa; TIMP-1, glycosylated TIMP-3 and TIMP-4, 24 kDa; unglycosylated TIMP-3, 21 kDa; TIMP-2) by reverse zymography and quantified by densitometric analysis.


RESULTS
No pregnancy was complicated by amniorhexis or preterm labor. At cesarean, normal volumes of amniotic and allantoic fluid were present in all cases. Histology of the plug sites revealed good integration of the collagen plug without complete restoration of membrane integrity. MMP-2, MMP-9, and TIMPs were detected in all fluids. In the operated animals, significantly (P <.05) higher activity of MMP-9 was found in amniotic fluid, with lower concentrations of TIMPs in allantoic fluid (P <.01). Tracheal occlusion was associated with a significant (P <.02) increase in both MMP-2 and -9 in tracheal fluid.


CONCLUSIONS
Collagen plugging of the fetoscopic access port sites in sheep resulted in functionally effective sealing of the fetal membranes. Changes in MMP-2, MMP-9, and TIMPs suggest an active remodeling of both the fetal lung and the fetal membranes.
Devlieger
R
R
Centre for Surgical Technologies, University Hospitals, Katholieke Universiteit Leuven, Minderbroedersstraat 17, 3000-Leuven, Belgium.
Riley
S C
SC
Verbist
L
L
Leask
R
R
Pijnenborg
R
R
Deprest
J A
JA
D000650:Amnion / Q000166:cytology / Q000201:enzymology; D000653:Amniotic Fluid / Q000737:chemistry / Q000201:enzymology; D000818:Animals; D002823:Chorion / Q000166:cytology / Q000201:enzymology; D004195:Disease Models, Animal; D005260:Female; D005332:Fetoscopy / Q000379:methods*; D005865:Gestational Age; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D009504:Neutrophils / Q000502:physiology; D011247:Pregnancy; D012756:Sheep; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism; D019717:Tissue Inhibitor of Metalloproteinase-3 / Q000378:metabolism; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*; D000097792:Tissue Inhibitor of Metalloproteinase-4
D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D019715:Tissue Inhibitor of Metalloproteinase-1; D019716:Tissue Inhibitor of Metalloproteinase-2; D019717:Tissue Inhibitor of Metalloproteinase-3; D019714:Tissue Inhibitor of Metalloproteinases; D000097792:Tissue Inhibitor of Metalloproteinase-4