Genes Dev. 24, 543–548 (2010)

Older mice are better able to regenerate liver tissue if they are pregnant.

Eli Pikarsky and Yehudit Bergman of the Hebrew University Hadassah Medical School in Jerusalem and their colleagues removed two-thirds of the livers of pregnant and non-pregnant mice of two different ages. Two days after the surgery, three-month-old non-pregnant mice had livers that were 82% of their original size, whereas livers in 12-month-old 'aged' mice were only about half (46%) their original size. Aged mice that were pregnant, however, had regenerated almost all (96%) of their liver tissue.

Heightened liver regeneration during pregnancy seemed to be due to increased cell growth rather than faster cell proliferation. Treating 18–24-month-old mice with a drug that activates a cell-growth signalling pathway called Akt/mTORC1 improved recovery after liver surgery.