Background: Low levels of vitamin D and diminished remodeling of the uterine spiral arteries (SpA) are associated with pre-eclampsia and fetal growth restriction. It is unknown whether vitamin D plays a direct role in mediating SpA remodeling, or modulates the ability of other cell types (uterine natural killer (uNK) cells or extravillous trophoblast cells) to mediate this process.
Methods: uNK cells and placental explants (PE) were isolated from first trimester (6-8 weeks gestation) decidua and placenta, and cultured in 25OHD (0, 10, 100nM) or 1,25(OH)2D (0, 1, 10nM) for 24 hours and conditioned medium (CM) harvested. Chorionic plate arteries were dissected from term placenta, cut into small portions and cultured in different CM generated above or 25OHD (0, 10, 100nM) or 1,25(OH)2D (0, 1, 10nM) for 5 days, sections were H&E stained and vascular smooth muscle (VSMC) organization assessed using a 4 point scale; 1=fully organized and 4=fully disorganized. VSMC migration and invasion in response to different CM and vitamin D were assessed by ExCElligence RTCA assay. VSMC cytoskeleton rearrangement was determined by immunofluorescence.
Results: uNK cell-CM induced VSMC disorganization, but PE-CM did not. 25OHD had no effect on VSMC organization, and did not alter the ability of uNK cells or PE to induce VSMC disorganization. In contrast, active vitamin D (1,25(OH)2D) induced VSMC disorganization in a dose dependent manner. In addition, in the presence of active vitamin D PE-CM was also able to induce VSMC disorganization, although there was no enhancement of the effect of uNK cell-CM. 1,25(OH)2D also increased PE secretion of G-CSF, and G-CSF alone could also induce VSMC changes. Active vitamin D induced VSMC migration, invasion and cytoskeleton rearrangement.
Conclusions: Vitamin D plays an important role in early stages of SpA remodeling, in both a direct manner and by altering the activity of other cell types.