Egg cells can live 50 years: these Barcelona researchers have just discovered why

Ovules are extremely long-lived cells that accompany, and on this depends the human ability to reproduce without excessive unwanted mutations in the process. A team of researchers from Barcelona Institute of Science and Technology and the Hospital Clínic de Barcelona has come up with the formula thanks to which these cells manage to stay alive and functional for half a century.

A limited number.
Females of all mammalian species are born with a limited number of eggs. This implies that a good part of their reproductive process depends on the longevity of these cells. In the case of humans, these eggs manage to stay alive and active for about 50 years.

Skip a step.
The key is in the process that cells use to obtain their energy, a process that occurs in the mitochondria. The energy of the cells is “stored” in molecules called ATP. To generate them, five protein complexes are involved.

The first four complexes carry an electron that is released when the first of them transforms the NADH molecule into NAD+, a process that releases hydrogen and electrons that move from complex to complex through the mitochondrial membrane. The process generates an electrical potential in the mitochondria membrane that activates the fifth protein complex, which is the one that culminates this process creating the ATP molecule.

The problem is that not all the electrons released in the first transformation remain in the membrane. Some escape generating reactive oxygen species (ROS), highly reactive molecules that can, on the one hand, damage the cell and, on the other hand, affect the genetic information contained in the mitochondria, causing potential mutations.

“Very surprising” results.
But this process does not occur in the ovules. Analyzing these cells, the team realized that the electrical pulse on the surface of the mitochondria of these cells was weaker than usual.

They thus discovered that these cells are the only ones known in the animal kingdom that skip the first of the steps and therefore the filtration of ROS. This prevents not only the deterioration of the cell as a whole but also of the genetic information contained in its mitochondria.

The details of the investigation have been published as an article recently in the journal Nature.

The longevity of cells.
It may seem like a trivial question, but the truth is that cells do not usually have such long lives. If we think about other human cells, life expectancy can vary a lot. Pancreatic cells live for about a year, as do liver cells.

Most intestinal cells live for a little over 15 years, while there are heart cells that reach 40. The longest are the cells of the eye lens and neurons, although as we well know, the latter can accumulate a substantial deterioration throughout our lives.

Health issue.
For decades, in the developed world, the average age at which women become pregnant has been delayed, with a substantial part of pregnancies produced after 40. The study can also help to understand why, although lower than in other types of cells, they do occur in ovules at these ages. Therefore, it can serve as a first step to avoid complications in these pregnancies.

Despite the general decline in birth rates, fertility is an important issue from a health point of view. Many advances have made pregnancy a much safer process for both mothers and babies.

Despite this, risk pregnancies continue to be counted by tens of thousands in Spain alone. Therefore, better understanding these possible risk factors from the cellular level can therefore help avoid problems in future stages of pregnancy.