Hibernating mitochondria as organ preservation: hibernator versus non-hibernator kidney mitochondria

K.D.W. Hendriks, R.H. Henning

Friday 16 march 2018

11:20 - 11:30h at Van Weelde Zaal

Categories: Basic / translational research, Session (parallel)

Parallel session: Parallel session 12: Basic/translational research

Hibernators are well known for their ability to initiate safe metabolic suppression and to resist ischemia and hypothermia, even outside the hibernation season. Therefore, hibernation is a promising strategy to mitigate cellular damage in a variety of conditions, such as organ transplantation. We explored the role of mitochondria herein, by analysing mitochondrial function during cold preservation and rewarming in epithelial cell lines from a hibernator (hamster kidney cells, HaK) and a non-hibernator (human embryonic kidney cells, HEK293).

Cells were subjected to cooling at 4^oC up to 16h, followed by rewarming. In addition to cell survival (Neutral Red assay), mitochondrial function was determined by adenosine triphosphate (ATP) levels (Luciferase assay), mitochondrial membrane potential (JC1 fluorescent dye) and mitochondrial morphology (MitoTracker fluorescent dye).

In HEK293, cooling induced dispersion of the tubular mitochondrial network, a loss of mitochondrial membrane potential and decreased ATP levels. In contrast, HaK maintained both mitochondrial membrane potential and ATP production during cooling and rewarming, resulting in superior cell survival compared to HEK293. Interestingly, HaK showed a dispersed mitochondrial network in both warm and cold conditions, whereas HEK293 cells showed a fused network in 37^oC.

To rule out cytosolic effects, ATP production was also measured in isolated mitochondria from HaK cells subjected to cooling. Remarkably, isolated HaK mitochondria incubated for 3h in 4^oC maintained their production of ATP.

Thus, we have showed that hibernation derived mitochondria are able to maintain their function during cold, whereas non-hibernating derived mitochondria fail. Disclosing the mechanisms that hibernators use to maintain mitochondrial function, resulting in attenuation of cell death, in hypothermic and ischemic circumstances may help to eventually improve organ preservation in organ transplantation.