Regulation of Fetal Lamb Ductus Arteriosus Smooth Muscle Cell Migration by Indomethacin and Dexamethasone

Abstract

ABSTRACT. Postnatal closure of the ductus arteriosus DEX, desamethasone (DA) requires the development, during late gestation, of Ao, aorta "intimal cushions." These structures, which partially oc-PC, prostaglandin clude the vessel lumen, are characterized by smooth muscle FN, fibronectin 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 cushionThe DA is an artery that, during fetal life, serves to divert the formation. SMC harvested from the DA and aorta of 100-flow of blood from the uninflated lungs to the systemic circulad fetal lambs were seeded onto three-dimensional collagen tion. With the initiation of breathing, the lungs are inflated and gels. Migration into the gels was quantitatively assessed the arterial oxygen saturation increases. Through a cytochrome by phase-contrast microscopy. INDO retarded DA SMC P-450 mechanism ( I ) probably linked to endothelin (2, 3), the migration (p < 0.05), but it had no effect on aorta SMC elevated oxygen tension produces a strong muscular contraction migration. Synthesis of FN was measured after ["SI-meoccluding the DA and increasing the flow of blood to the pulthionine radiolabeling of cells, gelatin sepharose extraction monary circulation. Independent of this reversible muscular of conditioned media, and resolution by SDS-PAGE. De-contraction, permanent closure of the DA requires a structural spite the decrease in migration, INDO did not affect FN change. namely, the development of "intimal cushions" (4). synthesis in DA SMC, whereas dexamethasone, a stabi-Failure of the DA to undergo obliteration. a common event in lizer of FN mRNA that increased DA FN synthesis by preterm newborns, allows blood to flow from the Ao into the 44%, had no further effect on SMC migration. We then pulmonary circulation and results in congestive heart failure. investigated whether INDO might be influencing SMC The development of intimal cushions. which occurs independmigration by decreasing collagenase production or altering ently of DA muscular contraction, involves changes in both the cell shape through changes in F-actin polymerization. Col-intima and the media of the vessel with increased deposition of lagenase activity, assessed by zymography using collagen hyaluronan in the subendothelial region associated with migratypes I and IV, was similar in control and treated DA and tion of SMC into this area (5). Studies by Boudreau and Rabiaorta cells. Image analysis of the actin cytoskeleton after novitch (6) revealed that DA SMC harvested from early gestation rhodamine-phalloidin staining of DA SMC, however, re-fetal lambs produced 2-fold more FN than SMC from the Ao. vealed significant shortening of INDO-treated DA SMC Furthermore, the increase in FN production by DA SMC was relative to control, consistent with the observed reduction associated with their enhanced migration rel...

Inhibition of cyclooxygenase isoforms in late- but not midgestation decreases contractility of the ductus arteriosus and prevents postnatal closure in mice

“…Interruption of smooth muscle differentiation leads to delayed postnatal ductus closure (24). Prostaglandins play an important role in vascular smooth muscle migration and differentiation (1,16,19). We hypothesize that prolonged COX inhibition on days 15-19 of gestation alters the development of the contractile apparatus that is essential for rapid constriction after birth.…”

A novel role for PGE2-EP4 in the developmental programming of the mouse ductus arteriosus: consequences for vessel maturation and function

“…Specifically, EP 4 -activated EPAC1 has been shown to promote smooth muscle cell (SMC) migration independent of matrix or proliferation in the rat DA ( 33 ). To determine if EP 4 plays a role in the vascular smooth muscle cell (VSMC) migration that leads to DA closure ( 61 – 64 ) in the mouse, we used a primary culture model. Low-passage VSMCs were cultured from explants of term mouse DA and Ao, shown to express mature muscle markers in >99% of cells ( Fig.…”

“…This may partially explain our observation of decreased tone and decreased responsiveness of the EP 4 KO DA to constrictive stimuli. SMC migration plays a key role in the permanent closure and fibromuscular remodeling of the DA ( 62 – 64 , 111 ). During development, VSMCs migrate inward from the media, cross the increasingly fenestrated internal elastic lamina, and relocate into the subendothelial space where they form a neointima of radially realigned SMCs ( 36 ) in preparation for postnatal closure.…”

Antenatal Administration of Betamethasone Contributes to Intimal Thickening of the Rat Ductus Arteriosus

“…To date, only one investigation has indicated the role of glucocorticoid in vascular SMC migration by showing that dexamethasone did not affect migration in cells isolated from lamb DA. 48 In other cell types, such as mesenchymal stem cells and melanoma cells, however, it has been demonstrated that glucocorticoid promotes migration. [25][26][27] Yun et al showed that dexamethasone stimulated human mesenchymal stem cell migration through the expression of FAK and paxillin, 26 both of which are essential for migration.…”