Scientists clone animals from freeze-dried skin cells for the first time

(ORDO NEWS) — The freeze drying process really surpasses its (very light) weight. It makes delicious chocolate-covered strawberries, gives astronauts more options to eat, and can now be used to store information about DNA and cells for cloning purposes.

With a success rate of only 0.2 percent. cell freeze-drying still has a long way to go before it becomes a standard cloning and storage strategy, but it is a truly exciting step.

“Maintaining biodiversity is an important task, but storing germ cells as genetic resources using liquid nitrogen is difficult, expensive and easily disrupted during natural disasters,” researchers led by Sayaka Wakayama from Yamanashi University in Japan. , write in their new article.

“Here, we show that freeze-dried somatic cells can produce healthy, fertile clones, suggesting that this technique may be important to create alternative, cheaper, and safer liquid nitrogen-free biobanking solutions.”

Freeze drying is a gentle, albeit intensive, process. Imagine that something is frozen in several stages until the temperature reaches -80 degrees Celsius (-112 degrees Fahrenheit), and then placed in a high pressure vacuum chamber.

This process turns water into ice without puncturing large ice crystals. cell walls, while pressure turns the water from a solid state directly into a gas, which is then sucked out of the product. This happens several times until the product is light and crispy, but still retains most of its texture.

Freeze drying is mainly used in the food industry where it keeps the nutrients and flavor intact. It is also used for pharmaceutical products and even occasionally for taxidermy.

Once the freeze-dried product has arrived at its destination, it can be rehydrated, keeping many of its properties the same. This is a fairly simple process and has been successfully used for decades. But doing this with cells, then using them to reproduce, is a completely different matter.

The same group of researchers experimented with storing freeze-dried semen in a drawer (without temperature control). ) for more than a year, and on the International Space Station for more than 5 years. Both gave viable offspring, although the success rate was in adolescence.

“Freeze-drying may be the best way to conserve genetic resources over the long term in a safe, inexpensive and location-independent way. ‘, the researchers write in their paper.

“However, to date, the only cells that give offspring after freeze-drying are mature spermatozoa. Collection of spermatozoa from infertile males and oocytes/embryos from fertile females is difficult. .”

When cloning animals, you need a non-reproductive cell (called a somatic cell) with all of the animal’s DNA. This package of nuclei, filled with DNA, can then be inserted into an egg, and with a little fiddling, you can begin the process of growing a baby.

Cloning is not the easiest way to preserve genetic information. material for the future, but it allows you to have all of an animal’s genetic material, not just the half found in reproductive cells.

Currently, somatic and reproductive cells—for biobanks or other purposes—can be stored in liquid nitrogen, which can be quickly heated to bring the cells back to life.

But the researchers wanted to see how freeze-drying worked, so they used mouse somatic cells (in this case, fibroblasts and cumulus cells), freeze-dried, and stored at -30 degrees Celsius (-22 degrees Fahrenheit) for up to nine months.

The cells did die and there was significant DNA damage, but the team was able to extract the rest of the genetic information and put it into new cells that became early embryonic cell lines.

Thes Then their nuclear information was extracted from the cell lines and inserted into a new embryo, which was able to create cloned mice.

So yes, it’s not a perfect process. Each correct step – from rehydration to creating a cell line and actually rearing cloned mice – occurred only 0.2% of the time. This places the method with an even lower chance of success than cloning Dolly the sheep, which had only a 0.4 percent chance of existing.

Some mice were also not proper clones, carrying epigenetic abnormalities due to DNA. damage. In one interesting case, a cell line lost its Y chromosome and changed from male to female, so there is still a lot of research to be done to regulate this process.

With that said, if the success rate eventually improves, the ability to clone animals using such degraded cells and DNA will be a boon in other areas as well. Over time, even the best-preserved DNA degrades; if we are to succeed in cloning extinct animals, we need to improve cloning from incomplete or degraded DNA.

It is very far from where we are now, but the future looks interesting.


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