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. OD₆₅₀ 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).

Conclusion

Our results suggest that these novel calcifying nanoparticles may play a role in placental calcification.

Keywords:

• calcifying nanoparticles
• nanobacteria
• placental calcification
• 16S rRNA gene

Acknowledgment

This study was supported by the National Natural Science Foundation for Young Scholars of China (31000075). We express our gratitude to the Obstetrics Department at the First Affiliated Hospital of Chongqing Medical University for help in obtaining the placental calcification samples.

Disclosure

The authors report no conflicts of interest in this work.