title: The effect of hydroxyapatite nanocrystals on microvascular endothelial cell viability and functions.
abstract: To favor bone reconstitution with biomaterials endothelial cells should maintain proper functions to drive angiogenesis. To this aim nanocrystals of hydroxyapatite (HA) have been synthesized and characterized on endothelial cells. Microvascular endothelial cells have been exposed to stoichiometric HA nanocrystals. Cell morphology and organization of cytoskeletal proteins have been monitored by SEM analysis and immunofluorescence. Biochemical markers of physiological and pathological responses of endothelial cells, endothelial constitutive nitric oxide synthase, and cycloxygenase-2 (ecNOS and COX-2, respectively) have been measured by immunofluorescence. Crystallized HA sustained endothelial survival without any cytotoxic effect. At the observation with SEM, endothelial cell morphology was maintained in the presence of HA. The localization and organization of beta-actin documented the formation of stress fibers, indicating an activation of endothelial cells induced by HA nanocrystals. Immunohistochemistry for biochemical key signaling pathways in endothelium demonstrated that nanocrystals of HA maintained the expression of ecNOS and did not increase COX-2 expression. In conclusion, the present findings indicate that HA nanocrystals exhibit high biocompatibility for microvascular endothelium. In the presence of HA nanocrystals endothelial cells maintain biochemical markers of healthy endothelium. They do not acquire a proinflammatory or thrombogenic phenotype, but express markers of functioning endothelium that might contribute to angiogenesis.
authors.affiliation: Section of Pharmacology, Department of Molecular Biology, University of Siena, Via A. Moro 2, 53100 Siena, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pezzatini
authors.forename: Raffaella
authors.initials: R
authors.lastname: Solito
authors.forename: Lucia
authors.initials: L
authors.lastname: Morbidelli
authors.forename: Stefania
authors.initials: S
authors.lastname: Lamponi
authors.forename: Elisa
authors.initials: E
authors.lastname: Boanini
authors.forename: Adriana
authors.initials: A
authors.lastname: Bigi
authors.forename: Marina
authors.initials: M
authors.lastname: Ziche
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000096:biosynthesis; D017886:Durapatite / Q000009:adverse effects; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D008422:Materials Testing / Q000379:methods; D008565:Membrane Proteins / Q000096:biosynthesis; D049329:Nanostructures / Q000009:adverse effects; D052250:Nitric Oxide Synthase Type III / Q000096:biosynthesis; D015398:Signal Transduction; D022502:Stress Fibers / Q000378:metabolism
chemical_list: D000199:Actins; D015415:Biomarkers; D008565:Membrane Proteins; D017886:Durapatite; D052250:Nitric Oxide Synthase Type III; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human