title: Aortic valve-derived calcifyng nanoparticles: no evidence of life.
abstract: OBJECTIVE
  Calcifying nanoparticles, also known as "nanobacteria," are very small bacteria-like structures (0.1-0.5 μm) 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.
  
  
  METHODS
  Calcifying nanoparticles were grown from 6 different valves randomly chosen among 84 consecutively explanted aortic valves, as described in the literature. The (1)H-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.
  
  
  RESULTS
  After 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. (1)H-NMR spectra showed no difference between calcifying nanoparticles and 6-week-old sterile culture media maintained under the same conditions.
  
  
  CONCLUSIONS
  Our results show that calcifying nanoparticles cannot be considered as living organisms.
authors: Institut de Recerca, Àrea del Cor, Hospital Universitari Vall d'Hebron, Universitat Autònoma de Barcelona, Barcelona, Spain. ignasi.barba@vhir.org
authors: Ignasi
authors: I
authors: Barba
authors: Eduardo
authors: E
authors: Villacorta
authors: Miguel-Angel
authors: MA
authors: Bratos-Perez
authors: Maria
authors: M
authors: Antolín
authors: Encarna
authors: E
authors: Varela
authors: Pedro Luís
authors: PL
authors: Sanchez
authors: Pilar
authors: P
authors: Tornos
authors: David
authors: D
authors: Garcia-Dorado
mesh_terms: D000368:Aged; D001021:Aortic Valve / Q000000981:diagnostic imaging / Q000473:pathology*; D059587:Calcifying Nanoparticles / Q000502:physiology*; D002130:Calcium Phosphates; D003470:Culture Media; D005260:Female; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D010316:Particle Size; D010363:Pattern Recognition, Automated; D016133:Polymerase Chain Reaction; D025341:Principal Component Analysis; D012336:RNA, Ribosomal, 16S; D014463:Ultrasonography
chemical_list: D059587:Calcifying Nanoparticles; D002130:Calcium Phosphates; D003470:Culture Media; D012336:RNA, Ribosomal, 16S; C020243:calcium phosphate