Stem cells are arguably one of the most well-researched things in the world. However, even though the said cells have been researched for quite some time now, we still do not know exactly how to utilize them.
We know that stem cells are able to produce a lot of copies of themselves and, when given the right conditions, they can also turn into whatever cell in the body as well.
For research and scientific purposes, the stem cells that are either created in the lab, derived from early embryos, or from manipulating adult stem cells using different chemical reagents, one thing is for certain- you will need to preserve them until use.
What do you usually do to preserve your meats? Well, you put them in the freezer, right? Although that was also the notion that many scientists believed, preserving stem cells by freezing may not be that cut and dry after all.
Although you can certainly freeze them, the entire process of doing so is quite tricky. You cannot just use your favorite freezing reagent, use conventional methods, and call it a day by sticking it into the freezer- you have to do some things first.
You see, the first scientists that used stem cells and have frozen them in an attempt to preserve it for later use, they’ve discovered that by using conventional methods of freezing, only a measly 5 percent of the stem cells survived.
According to Alexandra Stolzing, it appears that the natural stress that is caused by extremely cold temperatures may encourage cell differentiation. If this is done, the stem cells would be pushed towards a random tissue state (because of the differentiation) and you would lose any value that natural stem cells provide.
Furthermore, cells usually have a death sequence and certain conditions could potentially activate them. But, using inhibitors to the stem cell culture will not really yield positive results. Don’t get me wrong, the yield would improve, albeit slightly.
What Should You Use Then?
Well, the cryopreservation of stem cells requires different methods depending on the cell that is used. In most freezing protocols, however, there seems to be a fixed process.
A typical preservation method would make use of 90% fetal bovine serum or FBS and a 10% dimethyl sulfoxide solution (the latter protects the cells from the harmful effects of freezing).
Although this is effective, there is a concern about safety, especially when it is going to be used in human subjects. DMSO could lead to immune reactions, toxicity, and other possible side effects.
Moreover, using the standard 90% FBS/ 10% DMSO mixture could lead to poor effectivity of the cells after thawing.
How Do I Thaw Them and How Much Yield Should I Expect?
Well, speed is of the essence here. Most researchers would subject the stem cells in liquid nitrogen and when it is time to use them for research, they would thaw it by subjecting it into a 37C water and then resuspending it with growth medium.
As for the yield, it depends on your actual conditions and a little bit of luck. In most cases, careful handling of stem cells and by using the proper freezing/thawing techniques, you can expect to get a 40-50% yield.
