Abstract
Exposure of Chinese hamster ovary cells (CHO) to highly concentrated
feed solution during fed-batch cultivation is known to result in an
unphysiological osmolality increase (>300 mOsm/kg),
affecting cell physiology and morphology. Extending previous observation
on osmotic adaptation, the present study investigates for the first time
potential effects of hyperosmolality on CHO cells on both population and
single-cell level. We intentionally exposed CHO cells to hyperosmolality
of up to 545 mOsm/kg during fed-batch cultivation. Contrarily to an
expected osmosis effect promoting cell shrinkage,
hyperosmolality-exposed CHO cells showed a nearly triplicated volume
accompanied by ablation of proliferation. On the molecular level, we
observed a strong hyperosmolality-dependent increase in mitochondrial
activity in CHO cells compared to control. The companion article
“Hyperosmolality in CHO Culture: Effects on Proteome” provides a
proteome-based insight into the effects of hyperosmolality on
mitochondria. In contrast to mitochondrial activity,
hyperosmolality-dependent proliferation arrest of CHO cells was not
accompanied by DNA accumulation or caspase-3/7-mediated apoptosis.
Notably, we demonstrate for the first time a formation of up to eight
multiple, small nuclei in single hyperosmolality-stressed CHO cells. The
here presented observations reveal unknown hyperosmolality-dependent
morphological changes and support existing data on the osmotic response
in mammalian cells.