The purpose of this study was to prove the mechanism of mineralization, when hydroxyapatite (HAP) is formed in blood plasma. These observations were substantiated by in vitro simulation of HAP crystallization in the plasma of healthy adults in a controllable quasi-physiological environment (T = 37°C, pH = 7.4) and at concentrations of dissolved Ca and P ions that resemble those in the blood of healthy adults. Another objective of the study was to investigate the role of Mg2+, Na+Cl - and serum albumin, the main blood protein, in the formation of calcium phosphate. Mineralized aortic and mitral valves of the heart were obtained in operations on patients with rheumatic or septic acquired valvular disease. Macroscopic and histological analyses of these samples were conducted. Primary nanocrystals of HAP formed in the blood may take part in the mineralization of both cardiac valves and vessels. The penetration of HAP nanocrystals may be caused by breaks in the endothelium of blood vessels. The lowering of pH may result from substantial degradation in the valve tissue. The experimental data make it possible to conclude that albumin and Fetuin-A are structural proteins that are responsible for subsequent incorporation of HAP nanocrystals in newly formed bone tissue.

Anon, A. (2013). Ethical Principles for Medical Research Involving Human Subjects. World Medical Assotiation Declaration of Helsinki, 310(20), 206-208.

Cai, M. M., Smith, E. R. & Holt, S. G. (2015). The Role of Fetuin-A in Mineral Trafficking and Deposition. BoneKEy reports, 4, 672.

Combes, C. & Rey, C. (2002). Adsorption of Proteins and Calcium Phosphate Materials Bioactivity. Biomaterials, 23(13), 2817–23.

Dautova, Y. (2014). Fetuin-A and albumin alter cytotoxic effects of calcium phosphate nanoparticles on human vascular smooth muscle cells. PloS one, 9(5), 554-565.

Demer, L. L. & Tintut, Y. (2008). Vascular Calcification: Pathobiology of a Multifaceted Disease. Circulation, 117(22), 2938–2948.

Egan, K. P. (2011). Role for Circulating Osteogenic Precursor Cells in Aortic Valvular Disease. Arteriosclerosis, thrombosis, and vascular biology, 31(12), 2965–2971.

Giachelli, C. M. (1999). Ectopic calcification: Gathering Hard Facts About Soft Tissue Mineralization. The American Journal of Pathology, 154(3), 671–5.

Golub, E. E. (2011). Biomineralization and Matrix Vesicles in Biology and Pathology. Seminars in Immunopathology, 33(5), 409–17.

Jahnen-Dechent, W. (2011). Fetuin-A Regulation of Calcified Matrix Metabolism. Circulation Research, 108(12), 494–509.

Le Geros, R. Z. (2001). Formation and Transformation of Calcium Phosphates: Relevance to Vascular Calcification. Zeitschrift für Kardiologie, 90(3), 116–24.

Leopold, J. A. (2012). Cellular Mechanisms of Aortic Valve Calcification. Circulation. Cardiovascular interventions, 5(4), 605–614.

London, G. M. (2013). Mechanisms of Arterial Calcifications and Consequences for Cardiovascular Function. Kidney International Supplements, 3(5), 442–445.

Miller, J. D., Weiss, R. M. & Heistad, D. D. (2011). Calcific Aortic Valve Stenosis: Methods, Models, and Mechanisms. Circulation Research, 108(11), 1392–1412.

Miller, V. M. (2004). Evidence of Nanobacterial-Like Structures in Calcified Human Arteries and Cardiac Valves. American Journal of Physiology. Heart and Circulatory Physiology, 287(3), 1115–1124.

Neven, E. (2011). Cell Biological and Physicochemical Aspects of Arterial Calcification. Kidney International, 79(11), 1166–1177.

New, S. E. & Aikawa, E. (2013). Role of Extracellular Vesicles in de Novo Mineralization: an Additional Novel Mechanism of Cardiovascular Calcification. Arteriosclerosis, Thrombosis, and Vascular Biology, 33(8), 1753–1758.

Raoult, D. (2008). Nanobacteria are Mineralo Fetuin Complexes. Plos Pathogens, 4(2), 41-53.

Reynolds, J. L. (2004). Human Vascular Smooth Muscle Cells Undergo Vesicle-Mediated Calcification in Response to Changes in Extracellular Calcium and Phosphate Concentrations. Journal of the American Society of Nephrology, 15(11), 2857–2867.

Sage, A. P. (2011). Hyperphosphatemia-Induced Nanocrystals Upregulate the Expression of Bone Morphogenetic Protein-2 and Osteopontin Genes in Mouse Smooth Muscle Cells in Vitro. Kidney International, 79(4), 414–422.

Schlieper, G. (2011). A Red Herring in Vascular Calcification: “Nanobacteria” are Protein-Mineral Complexes Involved in Biomineralization. European Renal Association, 26(11), 3436–3439.

Smith, E.R. (2013). Serum Fetuin-A Concentration and Fetuin-A-Containing Calciprotein Particles in Patients With Chronic Inflammatory Disease and Renal Failure. Nephrology, 18(3), 215–221.

Thompson, B. & Towler, D. A. (2012). Arterial Calcification and Bone Physiology. Endocrinology, 8(9), 529–43.

Titov, A. & Larionov, P. 2007. Bone-like Hydroxyapatite Formation in Human Blood. Calcified Tissue International, 80, 58.

Titov, A. (2004). Hydroxyapatite Formation in Human Blood. Sao-Paulo: ICAM-BR, 362 p.

Titov, A., Larionov, P. & Shchukin, V. (2000). Possible formation of hydroxyapatite in blood. Report of Biochemistry, 7(2), 124-132.

Wu, C. Y. (2009). Fetuin-Albumin-Mineral Complexes Resembling Serum Calcium Granules and Putative Nanobacteria. PloS one, 4(11), 805-816.

Yarbrough, D. K. (2010). Specific Binding and Mineralization of Calcified Surfaces By Small Peptides. Calcified Tissue International, 86(1), 58–66.

Yiu, A. J. (2015). Vascular Calcification and Stone Disease. Journal of Cardiovascular Development and Disease, 2(3), 141–164.