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Cardio Calcification Close-Up

Electron microscopy reveals hydroxyapatite nanoparticles associated with all stages of calcification-related cardiovascular disease

by Celia Henry Arnaud
April 29, 2013 | A version of this story appeared in Volume 91, Issue 17

Credit: Sergio Bertazzo
Spherical hydroxyapatite nanoparticles are found in calcific lesions in aortic valves.
SEM image of hydroxyapatite particles in an aortic valve with calcific lesions. Light green soft polygons dot a rough dark green surface. At the top of the image, the coloration fades to red.
Credit: Sergio Bertazzo
Spherical hydroxyapatite nanoparticles are found in calcific lesions in aortic valves.

Accumulation of calcified material in the cardiovascular system affects millions of people, yet the detailed composition and architecture of the resulting lesions remain poorly understood. To get a close-up look, Molly M. Stevens, Sergio Bertazzo, and coworkers at Imperial College London used electron microscopy to analyze the lesions from people at different stages of calcific aortic valve disease (Nat. Mater., DOI: 10.1038/nmat3627). The researchers found nanoscale spherical particles of crystalline hydroxyapatite, a calcium phosphate mineral, in the lesions. Despite being chemically similar to bone, the nanoparticles are structurally different. Stevens and her coworkers were surprised to see the particles in the aortic valves of people who have no visible lesions but who have calcification elsewhere in the cardiovascular system. The researchers also found similar nanoparticles in calcific lesions caused by other cardiovascular diseases, including rheumatic fever and arteriosclerosis. They propose that the particles may be one of the first materials to form during calcification and are involved in the beginning stages of cardiovascular diseases, although they don’t yet know the role the particles play in mediating lesion formation.


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