title: Association between calcifying nanoparticles and placental calcification.
abstract: BACKGROUND
  The purpose of this study was to examine the possible contribution of calcifying nanoparticles to the pathogenesis of placental calcification.
  
  
  METHODS
  Calcified placental tissues and distal tissue samples were collected from 36 confirmed placental calcification cases. In addition, 20 normal placental tissue samples were obtained as a control group. All the tissue samples were cultured using special nanobacterial culture methods. The cultured calcifying nanoparticles were examined by transmission electron microscopy (TEM), and their growth was monitored by optical density (OD) at a wavelength of 650 nm. 16S rRNA gene expression of the cultured calcifying nanoparticles was also isolated and sequenced.
  
  
  RESULTS
  Novel calcifying nanoparticles wrapped with electron-dense shells between 50 nm to 500 nm in diameter were observed in the extracellular matrix of calcified placental tissues. They were detected in placental villi and hydroxyapatite crystals, and contained "nucleic acid-like materials". After isolation and four weeks of culture, 28 of 36 calcified placental tissue samples showed white granular precipitates attached to the bottom of the culture tubes. OD(650) measurements indicated that the precipitates from the calcified placental tissues were able to grow in culture, whereas no such precipitates from the control tissues were observed. The 16S rRNA genes were isolated from the cultured calcifying nanoparticles and calcified placental tissues, and their gene sequencing results implied that calcifying nanoparticles were novel nanobacteria (GenBank JF823648).
  
  
  CONCLUSIONS
  Our results suggest that these novel calcifying nanoparticles may play a role in placental calcification.
authors.affiliation: Molecular Medicine and Tumor Research Center, Chongqing Medical University, Yuzhong District, Chongqing, People's Republic of China.
authors.forename: Yanan
authors.initials: Y
authors.lastname: Guo
authors.forename: Dechun
authors.initials: D
authors.lastname: Zhang
authors.forename: He
authors.initials: H
authors.lastname: Lu
authors.forename: Shuang
authors.initials: S
authors.lastname: Luo
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Shen
mesh_terms: D000328:Adult; D059587:Calcifying Nanoparticles / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D002114:Calcinosis / Q000235:genetics / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D046508:Culture Techniques; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D017886:Durapatite / Q000737:chemistry; D005260:Female; D006801:Humans; D008969:Molecular Sequence Data; D010316:Particle Size; D010920:Placenta / Q000737:chemistry* / Q000473:pathology; D010922:Placenta Diseases / Q000235:genetics / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D011247:Pregnancy; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D059587:Calcifying Nanoparticles; D012336:RNA, Ribosomal, 16S; D004247:DNA; D017886:Durapatite