Regulation of fetal lamb ductus arteriosus smooth muscle cell migration by indomethacin and dexamethasone.
Postnatal closure of the ductus arteriosus (DA) requires the development, during late gestation, of "intimal cushions." These structures, which partially occlude the vessel lumen, are characterized by smooth muscle cell (SMC) migration into an expanded subendothelium. DA SMC migration is dependent upon increased fibronectin (FN) production. We hypothesized that indomethacin (INDO) or dexamethasone, which could influence FN production, may affect SMC migration and DA intimal cushion formation. SMC harvested from the DA and aorta of 100-d fetal lambs were seeded onto three-dimensional collagen gels. Migration into the gels was quantitatively assessed by phase-contrast microscopy. INDO retarded DA SMC migration (p < 0.05), but it had no effect on aorta SMC migration. Synthesis of FN was measured after [35S]-methionine radiolabeling of cells, gelatin sepharose extraction of conditioned media, and resolution by SDS-PAGE. Despite the decrease in migration, INDO did not affect FN synthesis in DA SMC, whereas dexamethasone, a stabilizer of FN mRNA that increased DA FN synthesis by 44%, had no further effect on SMC migration. We then investigated whether INDO might be influencing SMC migration by decreasing collagenase production or altering cell shape through changes in F-actin polymerization. Collagenase activity, assessed by zymography using collagen types I and IV, was similar in control and treated DA and aorta cells. Image analysis of the actin cytoskeleton after rhodamine-phalloidin staining of DA SMC, however, revealed significant shortening of INDO-treated DA SMC relative to control, consistent with the observed reduction in migration.(ABSTRACT TRUNCATED AT 250 WORDS)
Koppel
R
R
Division of Neonatology, Hospital for Sick Children, Toronto, Ontario, Canada.
Rabinovitch
M
M
D000199:Actins / Q000378:metabolism; D000818:Animals; D002465:Cell Movement / Q000187:drug effects; D017364:Collagenases / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004373:Ductus Arteriosus / Q000166:cytology / Q000187:drug effects* / Q000196:embryology; D005333:Fetus / Q000187:drug effects*; D005353:Fibronectins / Q000096:biosynthesis; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000196:embryology; D012756:Sheep
D000199:Actins; D005353:Fibronectins; D003907:Dexamethasone; D017364:Collagenases; D007213:Indomethacin