Pulmonary trophoblastic deportation in the hystricomorph rodent Lagostomus maximus

Trophoblast has been reported in the lungs of gestating eutherian mammals with hemochorial placenta, including humans, cotton rats, and American hares. This study describes the discovery of trophoblastic-like cells in the lungs of Lagostomus maximus.

Lung and placenta samples from non-pregnant and pregnant plains viscachas were analyzed using histology and immunohistochemistry.

Macroscopically, the lungs of females in both groups showed no alterations, but microscopic examination of the lungs from pregnant females revealed lesions and trophoblast-like cells. Markers such as pancytokeratin, MMP-2, MMP-9, and progesterone receptors were found in both pulmonary trophoblastic cells and the various types of trophoblasts in the placenta and subplacenta. Notably, cytokeratin-7 showed similarity with the placenta but not with the subplacenta. Cells identified in the lungs that were positive for markers similar to trophoblast giant cells in the maternal blood chambers suggest that the trophoblast that reaches the lungs may originate from giant cells that enter maternal blood circulation rather than those that invade the uterine artery. Immunohistochemical analysis indicated that, unlike placental trophoblast, the lung cells exhibited no proliferative activity.

The lack of this process in mice and the difficulty of developing in vivo experimental models have prompted the exploration of in vitro models. L. maximus may serve as an alternative model to study this process, necessitating further research to determine the timing of this phenomenon during gestation and whether pulmonary alterations persist after parturition.