Late Breaking Abstract - Do inhaled carbonaceous particles translocate from the lung to the placenta?

Abstract

Introduction: Epidemiological studies have reported an association between maternal exposure to particulate matter (PM) air pollution and adverse effects on the fetus. However the mechanisms for these associations remain unknown.

Aims: We sought evidence for a direct effect of black carbon (BC) from inhaled PM, via translocation from the lung to the placenta.

Methods: With written consent, placental macrophages (PMacs), cells with marked phagocytic potential, were obtained from human placentas after elective caesarean section. Placental tissue was digested with trypsin, displace, and hyaluronidase; and PMacs extracted using a monocyte enrichment cocktail. PMacs were imaged under light microscopy (x100), the cumulative area of black material measured by image analysis (µm²/ 700 cells). Evidence of ultrafine particle phagocytosis by PMacs was also sought using electron microscopy (EM).

Results: Placentas from 5 women were studied. Of the 3500 PMacs analysed, 60 contained a total of 72 separate black inclusions, with morphology compatible with phagocytosed carbonaceous PM (Fig 1A). Mean cumulative BC area per placenta was 5.233µm² (total area 26.167µm²). 2 placentas were analysed by EM. Both showed black inclusions within phagolysosomes (Fig 1B), with morphology compatible with inhaled BC (Bunn, H.J. et al., Thorax 2001;56:932–934).

Conclusion: This study provides the first evidence that inhaled PM translocate from the lung to the placenta.