With a low success rate of 0.2%, freeze-drying cells are still a long way before it becomes the standard technique for cloning and storage, but it’s a really exciting step.
“Biodiversity conservation is an important task, but storing germ cells as genetic resources using liquid nitrogen is difficult, expensive, and easy to neutralize during disasters,” said the lead researchers. by Sayaka Wakayama of Yamanashi University in Japan in their new paper. “We show that freeze-dried somatic cells can produce healthy, efficient clones, suggesting that this technology could be important for creating alternative, cheaper, safer, nitrogen-free ones. biobanking solution. ”
Freeze-drying is a gentle, though intense, process. Imagine gradual freezing of an object until it reaches -80 ° C (-112 ° F) before it is placed in a vacuum chamber under high pressure.
This process converts water to ice without large ice crystals penetrating the cell walls, while pressure converts water from a solid directly to a gas that is then absorbed from the product. This happens several times until the substance is light and crunchy, but most of its structure is still intact.
Freeze drying is often used in the food industry because it keeps nutrients and flavor intact. It is also used for pharmaceutical products and sometimes even for embalming.
Once the freeze-dried product has reached its destination, it can be rehydrated, keeping many properties intact. This is a very simple process and has been successfully done over decades.
So far, the same team of researchers has tried to store freeze-dried sperm in a desk drawer (no temperature control) for more than a year and more than 5 years on the International Space Station. Both produced viable offspring.
In their paper, the researchers wrote: “Freeze-drying may be the best way to preserve genetic resources over the long term in a safe, inexpensive, and site-independent manner. But until now, only progeny cells in subsequent generations were freeze-drying mature sperm. Barren men and fertile women. the eggs/embryos are hard. ”
When cloning animals, you need a non-reproductive cell (called a somatic cell) that contains all of the animal’s DNA. This bundle of nuclei full of DNA can be inserted into an egg cell and with a little fiddling you can begin the process of developing a child.
Cloning is not the easiest way to preserve genetic material for the future, but it allows you to capture all of an animal’s genetic material, unlike half that is found in reproductive cells.
Currently, somatic and reproductive cells – for biobanks or other purposes – can be stored in liquid nitrogen, whose temperature can rise rapidly to restore the life of the cells.
But the researchers wanted to know how freeze-drying accumulates, so they used mouse somatic cells (in this case fibroblasts and cumulus cells), dried and maintained at -30 ° C (-22 ° F) until nine. moon.
The cells died and there was some major DNA damage, but the team retrieved the remaining genetic information and implanted it into new cells that became early embryonic cell lines.
The nuclear information of these cell lines is taken and inserted into a new embryo capable of producing cloned mice. So yes, it’s not a perfect process. And every step correctly, from rehydration to cell line formation to raising truly cloned mice, occurred only 0.2% of the time. This method provides a lower chance of success than cloning Dolly the sheep, whose survival rate is only 0.4%.
Some mice are also not viable clones and carry genetic abnormalities due to DNA damage. And in an interesting case, the cell line lost the Y chromosome and passed from male to female, so a lot of research needs to be done to fix this process.
With all that said, the ability to clone animals using damaged cells and DNA will be a blessing in other fields, if success eventually increases. Over time, preferably, the stored DNA decreases; And if we are going to have the opportunity to clone dead animals, we will need to improve the cloning process from missing or damaged DNA.
They are far from where we are today, but the future looks promising.
The research was published in the journal Nature Communications.
Source: Science Alert
Source: Arabic RT
