Aortic Valve-derived Calcifyng Nanoparticles: No Evidence of Life

Abstract

Introduction and objectivesCalcifying nanoparticles, also known as “nanobacteria,” are very small bacteria-like structures (0.1-0.5μm) with the ability to facilitate the precipitation and growth of calcium phosphate in pathological conditions and have been associated with aortic valve calcification. The status of nanobacteria is controversial; some have proposed that they are a new class of living organism while others describe calcifying nanoparticles as mineralo-fetuin complexes. The objective of the present study is to elucidate if calcifying nanoparticles are living entities, based on whether or not they have metabolic activity, a characteristic of life, irrespective of their composition. MethodsCalcifying nanoparticles were grown from 6 different valves randomly chosen among 84 consecutively explanted aortic valves, as described in the literature. The 1H-NMR spectra were acquired from calcifying nanoparticles culture media to assess metabolic changes and the presence of 16sRNA in the culture media was investigated by real-time polymerase chain reaction. ResultsAfter 6 weeks in culture, calcifying nanoparticles could be seen clearly attached to the surface of culture flasks. All samples were negative for 16sRNA, discarding the presence of known bacteria. 1H-NMR spectra showed no difference between calcifying nanoparticles and 6-week-old sterile culture media maintained under the same conditions. ConclusionsOur results show that calcifying nanoparticles cannot be considered as living organisms.