Animals Have Been Cloned From Freeze-Dried Skin Cells in a Scientific First

Freeze drying is a technique that truly outperforms its (relatively) little weight. In addition to providing astronauts with more food options and making for a delectable chocolate-covered strawberry, the technology may now be used to store DNA and cell information for cloning.

Freeze drying of cells is a truly exciting advance, but it still has a long way to go before it becomes a common cloning and storage technique with success rates as low as 0.2 percent.

According to researchers lead by Sayaka Wakayama from the University of Yamanashi in Japan, "maintaining biodiversity is a crucial duty, but preserving germ cells as genetic resources using liquid nitrogen is difficult, costly, and easily disturbed during disasters."

Here, we demonstrate the ability of freeze-dried somatic cells to create healthy, viable clones, indicating the potential significance of this technology for the development of substitute, less expensive, and safer liquid nitrogen-free biobanking solutions.

Although tedious, freeze drying is a gentle technique. Imagine putting anything in a vacuum chamber under high pressure after it has been repeatedly frozen until it reaches -80 degrees Celsius (-112 degrees Fahrenheit).

Without the need for huge ice crystals to pierce the cell walls, the process transforms water into ice, while the pressure converts water from a solid to a gas that is subsequently drawn out of the product. The process is repeated several times to produce an object that is light and crunchy but yet retains the bulk of its structural integrity.

The food sector uses freeze drying the most because it preserves tastes and nutrients. Pharmaceuticals and occasionally even taxidermy utilize it as well.

The object can be rehydrated once it has reached its destination, preserving many of its original features. This procedure is rather straightforward and has been carried out successfully for many years. But doing this to cells that will later be used for reproduction is a whole other matter.

This same study team has tested preserving freeze-dried sperm on the International Space Station for more than five years as well as in a desk drawer for more than a year without temperature control. Though the success rate was in the teens, both produced live offspring.

The researchers argue in their report that freeze drying "may be the greatest strategy to conserve genetic resources for a long amount of time in a safe, low-cost, and location-independent manner."

"However, only fully developed spermatozoa have so far given birth after being freeze dried. It is challenging to obtain spermatozoa from infertile guys and oocytes or embryos from viable females."

To clone an animal, you need a somatic cell, a non-reproductive cell that contains all of the animal's DNA. The process of creating a baby can then be initiated by inserting this nucleus package, which is packed with DNA, into an egg cell.

Cloning gives you access to an animal's whole genetic makeup rather than just the portion present in reproductive cells, yet it is not the most convenient method for preserving genetic information for the future.

Currently, liquid nitrogen may be used to preserve somatic and reproductive cells, which can then be swiftly warmed up to reactivate the cells for use in biobanks or other applications.

However, the researchers employed mouse somatic cells (in this case, fibroblasts and cumulus cells), freeze dried, and maintained at -30 degrees Celsius (-22 degrees F) for up to nine months in order to compare freeze drying to other methods.

The scientists did able to remove the remaining genetic material and insert it into new cells, which produced early embryo cell lines, despite the fact that the cells did perish and there was severe DNA damage.

In order to make cloned mice, the nuclear information from these cell lines was then removed and placed into a fresh embryo. Therefore, this procedure is not flawless. Only 0.2 percent of the time did every process, including rehydration, cell line creation, and real mouse growth, proceed according to plan. The technology now has even fewer chances of working than the sheep Dolly, whose cloning had a 0.4 percent probability of succeeding.

Due to DNA damage, some mice were not true clones and had epigenetic anomalies. There is still much to learn about how to optimize this process since in one intriguing instance, the cell line lost its Y chromosome and switched from being male to female.

Having said that, cloning animals from such damaged cells and DNA would be beneficial in other ways as well if the success rate finally increases. Even the best-preserved DNA deteriorates with time, so we'll need to grow better at cloning from incomplete or deteriorated DNA if we hope to successfully revive extinct animals.

Although this is a long way from where we are right now, the future seems exciting.