Pathomorphological pattern of the mouse lungs and liver after repeated intratracheal instillation with different carbonaceous nanomaterials

Introduction : With the development of nanotechnology, toxicity of nanomaterials has received considerable attention. This study focused on the pathomorphology of lungs and liver in mice exposed by intratracheal instillation to four carbonaceous nanomaterials, once a week for 7 consecutive weeks. Materials and Methods : NMRI mice (six males/group, 6-weeks old; Taconic, Ry, Denmark) were intratracheally instilled with graphene oxide (18 mg/animal), carbon black nanomaterials: flammruss 101 (0.1 mg/animal) and printex 90 (0.1 mg/animal), or diesel exhaust particles SRM1650b (0.1 mg/animal) dispersed in 50 ml of nanopure water (vehicle) by sonication.

The control group received nanopure water. The instillation of particle suspension or with vehicle alone was followed by 200 ml of air under general anaesthesia with isoflurane. Microscopical pattern of the lungs and liver (HE-stained sections) was evaluated 6 to 8 days after the last instillation. Results : In the lungs of exposed mice, foreign material was seen as small to aggregated granules situated in the alveolar lumen, wall, bronchioles and in connective tissue.

Graphene oxide and SRM1650b were present as larger aggregates compared with flammruss 101 and printex 90 and were located as free material or in macrophages. Foreign material was not observed in any liver from the exposed mice. Congestion, extravasation, oedema of the alveolar wall and interstitial pneumonia were present in the lungs after exposure to the test materials.

In the liver, necrosis and karyomegaly were observed. Conclusions : The morphological changes of the lungs and liver were most severe after exposure to graphene oxide and least severe after exposure to flammruss 101.