title: Mast cells, neovascularization, and microhemorrhages are associated with saccular intracranial artery aneurysm wall remodeling.
abstract: Chronic inflammation contributes to remodeling, degeneration, and rupture of saccular intracranial artery aneurysms. Mast cells are important proinflammatory and proangiogenic cells in chronic inflammatory vascular diseases. Here we studied mast cells and neovascularization in 36 intraoperatively resected aneurysms using histology and immunohistochemistry and analyzed the clinical characteristics of the aneurysms according to bleeding status (unruptured vs ruptured). Among the 36 aneurysms, 9 contained mast cells (tryptase-positive cells) and 15 contained neovessels (CD34- and CD31-positive capillarylike structures). The density of neovessels was significantly higher in aneurysm walls containing mast cells than in walls not containing them. In particular, wall areas with abundant mast cells and neovessels also contained iron deposits, indicating damage of newly formed endothelium with ensuing microhemorrhages. Walls with the highest neovessel density and the greatest iron deposition also showed evidence of degeneration. Finally, none of the mast cell-containing aneurysms showed an intact luminal endothelium. Thus, mast cells may adversely affect both neovascular and luminal endothelia. The novel association of mast cells with neovessels and injurious microhemorrhages, as well as with luminal endothelial erosion, suggests that mast cells contribute to remodeling and degeneration of saccular intracranial artery aneurysms.
authors.affiliation: From the Doctoral Program in Biomedicine, Doctoral School in Health Sciences, University of Helsinki (EO); Neurosurgery Research Group (EO, RT, JF, PH, JH, MN) and Wihuri Research Institute (EO, SL, PTK), Biomedicum; Department of Neurosurgery, Helsinki University Central Hospital (JH, MN), Helsinki; and Department of Neurosurgery, Kuopio University Hospital (JF), Kuopio, Finland.
authors.forename: Eliisa
authors.initials: E
authors.lastname: Ollikainen
authors.forename: Riikka
authors.initials: R
authors.lastname: Tulamo
authors.forename: Juhana
authors.initials: J
authors.lastname: Frösen
authors.forename: Satu
authors.initials: S
authors.lastname: Lehti
authors.forename: Petri
authors.initials: P
authors.lastname: Honkanen
authors.forename: Juha
authors.initials: J
authors.lastname: Hernesniemi
authors.forename: Mika
authors.initials: M
authors.lastname: Niemelä
authors.forename: Petri T
authors.initials: PT
authors.lastname: Kovanen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017542:Aneurysm, Ruptured / Q000150:complications*; D064752:Atrial Remodeling / Q000502:physiology*; D002536:Cerebral Arteries / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000209:etiology*; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D002532:Intracranial Aneurysm / Q000150:complications*; D007501:Iron / Q000378:metabolism; D050356:Lipid Metabolism; D008297:Male; D008407:Mast Cells / Q000473:pathology*; D008875:Middle Aged; D009389:Neovascularization, Pathologic / Q000209:etiology*; D055815:Young Adult
chemical_list: D016207:Cytokines; D007501:Iron