Ultrastructural imaging reveals vascular remodeling in migraine patients

Abstract

Migraine is a neurological disorder and one of the most common pain conditions worldwide. Despite its prevalence, the basic biology and underlying mechanisms contributing to the development of migraine are still poorly understood. It is still unclear, for instance, whether the vasculature, both extra and intracranial, plays a significant role in the generation of migraine pain. Neuroimaging data, indeed, have reported conflicting results on blood vessels abnormalities like vasodilation, while functional studies suggest that vessels dysfunction may extend beyond vasodilation. Here we combined light and electron microscopy imaging to investigate the fine structure of superficial temporal (STA) and occipital arteries (OA) from patients that underwent minimally invasive surgery for migraine. Using optical microscopy, we observed that both STA and OA vessels showed marked endothelial thickening and internal elastic lamina fragmentation. In the muscular layer, we found profound shape changes of vascular smooth muscle cells (VSMCs), abundant extracellular matrix, and the presence of clear extracellular vacuoles. The electron microscopy analysis confirmed putative VSMCs infiltrated within the intima layer and revealed a consistent shifting of VSMCs from contractile to a synthetically active phenotype. We also report the presence of (i) abundant extracellular vacuoles filled with fine granular material and membranes, (ii) multilamellar structures, (iii) endosome-like organelles, and (iv) bona fide extracellular vesicles in the matrix space surrounding synthetically active cells. As both the endothelial layer and VSMCs coordinate a variety of vascular functions, these results suggest that a significant vascular remodeling is occurring in STA and OA of migraine patients. Thus, this phenomenon may represent an important target for future investigation designed toward the development of new therapeutic approaches.

Keywords: Microscopy; Migraine disorders; Pain; Phenotypic switching; Vascular remodeling; Vascular smooth muscle cell.