Ps-b01-10: ultrastructural changes in systemic resistance arteries of hypertensive and normotensive women with uterine fibroids

Background: Uterine fibroids, the most common benign neoplasm in women, are associated with hypertension, but the nature of this association is not known. To assess a possible shared pathology of smooth muscle, we studied the ultrastructure of systemic resistance arteries of women with fibroids. Methods: Resistance-sized arteries (200 to 400 micrometer) were harvested from omental samples obtained during fibroid surgery. Transmission electron microscopic images were taken at different magnifications and locations of the vessel wall to assess qualitative and morphological characteristics. Results: We obtained resistance arteries of 19 women (9 hypertensive). Vessels of 17 women (8 hypertensive, 4 treated, none controlled) were available for analysis (Table). The arteries of normotensive and hypertensive women showed myocyte-like cells in the intima forming focal neo-intima plaques. In the media, myocytes showed a reduction in contractile fibers and prominent, dilated sarco-endoplasmic reticulum, with elongated mitochondria, and abundant autophagic and extracellular vacuoles. More profound ultrastructural changes were seen in hypertensives. Untreated hypertensives had a significantly higher media-to-lumen ratio than normotensives. Conclusion: To our knowledge these are the first data on the ultrastructure of systemic resistance-sized arteries in women with fibroids, showing vascular remodeling in both normotensives and hypertensives, with a shift from a contractile phenotype to a myocyte with prominent organelles involved in biosynthesis (synthetic phenotype). These abnormalities in systemic resistance-sized arteries may indicate that uterine fibroids are a manifestation of underlying systemic pathology affecting smooth muscle, or that fibroids induce systemic effects on the arterial wall, either directly or through factors that increase blood pressure, which needs exploration in further studies.