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Nano-analytical electron microscopy reveals fundamental insights into human cardiovascular tissue calcification

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Abstract

The accumulation of calcified material in cardiovascular tissue is thought to involve cytochemical, extracellular matrix and systemic signals; however, its precise composition and nanoscale architecture remain largely unexplored. Using nano-analytical electron microscopy techniques, we examined valves, aortae and coronary arteries from patients with and without calcific cardiovascular disease and detected spherical calcium phosphate particles, regardless of the presence of calcific lesions. We also examined lesions after sectioning with a focused ion beam and found that the spherical particles are composed of highly crystalline hydroxyapatite that crystallographically and structurally differs from bone mineral. Taken together, these data suggest that mineralized spherical particles may play a fundamental role in calcific lesion formation. Their ubiquitous presence in varied cardiovascular tissues and from patients with a spectrum of diseases further suggests that lesion formation may follow a common process. Indeed, applying materials science techniques to ectopic and orthotopic calcification has great potential to lend critical insights into pathophysiological processes underlying calcific cardiovascular disease.

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Figure 1: DDC-SEM micrographs of human aortic valve tissue.
Figure 2: Elemental analyses of dense structures identified on aortic valves.
Figure 3: Histograms describing the prevalence of dense calcium- and phosphorus-containing structures on the surface of aortic valves.
Figure 4: TEM images, EDS mapping and SAED analyses of aortic valve tissues sectioned with a FIB.
Figure 5: DDC-SEM micrographs of mitral valve, aorta and coronary artery, and TEM, SAED and EDS mapping of calcific lesions on coronary artery tissue sectioned using a FIB.

Change history

  • 24 April 2013

    In the version of this Article originally published online, the first name of the fourth author was incorrect: it should have read 'Adrian H. Chester'. This error has been corrected in all versions of the Article.

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Acknowledgements

S.B. was supported by the Rosetrees Trust and the Junior Research Fellowship scheme at Imperial College London. E.G. was supported by a fellowship from the Wellcome Trust. K.L.C. was supported by a studentship from the British Heart Foundation Centre of Research Excellence at Imperial College London. M.M.S. gratefully acknowledges financial support from the Rosetrees Trust. We would like to thank K. Nitiputri for providing the murine osteoblast cells line MC3T3-E1. We would like to acknowledge the provision of preliminary animal tissues by W. Jahnen-Dechent and A. Kinkeldey.

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S.B. designed the study, performed sample preparation, conducted all the experimental work, carried out data interpretation and aided with manuscript preparation and writing. E.G. aided with study design and data interpretation and wrote most of the manuscript. K.L.C. helped with sample preparation. A.H.C. and M.H.Y helped with sample procurement and aided in data interpretation. M.M.S. supervised the study, aided with study design and data interpretation and revised the manuscript.

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Correspondence to Molly M. Stevens.

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Bertazzo, S., Gentleman, E., Cloyd, K. et al. Nano-analytical electron microscopy reveals fundamental insights into human cardiovascular tissue calcification. Nature Mater 12, 576–583 (2013). https://doi.org/10.1038/nmat3627

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