Are VSELs the Sasquatch of the Stem Cell Field?

One of the more controversial areas in the stem cell field has been over a Sasquatch like stem cell type that only a handful of researchers have been able to find and study: very small embryonic-like stem cells (VSELs).

A Sasquatch is a generally thought to be mythological creature from the Pacific Northwest area of the US where I grew up, also sometimes called Big Foot.

Some folks believe in the Sasquatch. Some people believe in VSELs too.  I’m more interested in what you think about VSELs than stating my own opinion at this point. Please take our poll above.


As a kid growing up I did not believe in Sasquatch, but I still thought it was a cool, fun idea… and honestly as a kid out in the woods hiking or camping at night I sometimes wondered….

You’ll note in the map of Bigfoot/Sasquatch sightings at right from Wikipedia that my home state of Washington is the epicenter!

But clinically-related science cannot be based on outlandish, fun ideas that lack data, right? One hopes so.

So are VSELs real and clinically important or more like Big Foot?

VSELs received a trio of bad news today with three skeptical and even outright negative pieces coming out:

  • A research article in Stem Cell Reports from Irv Weissman’s group (Miyanishi, et al) entitled “Do Pluripotent Stem Cells Exist in Adult Mice as Very Small Embryonic Stem Cells?”
  • An opinion piece in Cell Stem Cell by Henry Nicholls
  • And a skeptical newsy piece in Nature by Alison Abbott entitled, “Doubt cast over tiny stem cells”.

VSELs are part of the portfolio of the stem cell biotech NeoStem (see my interview here with CEO Robin Smith, which includes mention of VSELs) and NeoStem has received almost $5 million in US government grants, an astonishing amount, to study VSELs, even as the stem cell field has serious doubts about the cells and other stem cell researchers struggle to get NIH or DoD funding.

A quote from the Abbott piece citing the Weissman article tells the story about how  much skepticism there is today:

“…in a major blow to the field, a paper published on 24 July in Stem Cell Reports suggests that the diminutive stem cells are not real1.”

Mariusz Ratajczak, the main proponent of VSELs.
Mariusz Ratajczak, the main proponent of VSELs.

Mariusz Ratajczak (see image at left from Nature) is the main proponent of VSELs. He’s facing a lot of heat today.

In the piece, entitled “VSELs: Is Ideology Overtaking Science”, Henry Nicholls discusses the main VSEL issues and includes a quote from stem cell leader, George Daley, which is very critical of VSELs:

“This rigorous approach just hasn’t been taken with VSELs. I find the work mystifying and lacking in rigor.”

That is very harsh for a public statement.

Nicholls’ piece also quotes Ratajczak that even he thinks that maybe things have moved a bit too fast for VSELs:

“Even Mariusz Ratajczak, director of the developmental biology research program at the University of Louisville’s James Graham Brown Cancer Center and the lead author of the paper that brought VSELs into the literature, is anxious about the pace at which they are being pushed. “I’m a little bit scared because I know that NeoStem would like to go fast to the clinic,” he says. “I still think we need to do more basic research.”

However, Ratajczak explains the difficulties that other researchers have had with VSELs as being due to lack of consistency in experimental methodology:

“In studying rare populations of cells, one needs to compare apples to apples, which unfortunately was not done”

And other researchers are quoted who believe very much in VSELs.

“I don’t see the controversy — we have seen bone grow” from VSELs in mice, says Russell Taichman, a researcher in dental medicine at the University of Michigan in Ann Arbor. Taich­man will be running the Neostem-backed VSEL trial, which will look for bone regrowth in dental patients. Announced in April, the trial is awaiting approval by the US Food and Drug Administration.

Abbott’s piece suggests there is a major political element to the VSEL area of stem cell research involving alleged retaliation against those who report negative findings about VSEL:

… Józef Dulak at the Jagiellonian University in Krakow, failed to find traces of VSELs in his experiments. When he published his findings in May4, Ratajczak tried to force him out of the consortium. Dulak, like Weissman, found no molecular signatures associated with pluripotency in any mouse bone-marrow cells smaller than 7 micrometres across.

In the end, science will prevail and tell us if VSEL are real or not, but there is no place for politics, religion, or retaliation here.

Again, tell us what you think in the poll above about VSELs.

6 thoughts on “Are VSELs the Sasquatch of the Stem Cell Field?”

  1. Pingback: Cells Weekly – July 28, 2013 | Stem Cell Assays

  2. It’s always a warning sign when (1) no independent lab can reproduce a result that claims to be a breakthrough in the field and (2) the lab that made the discovery publishes about 10X more review articles than primary research.

  3. As I stated in my letter in Stem Cells Dev. 2012 Sep 20;21(14):2561-2:

    “…one cell could “deserve” a “stem cell” “title” on the basis of what it is able to do and not what it looks like. With that respect, the pluripotent nature of VSELs could be judged and proved only on the basis of their potential to differentiate into functional cells of all tissues (meaning of term “pluripotent”)”.

    Thus, if one is referring to a “stem cell” only functional definition is able to confirm the existence of this entity. Of course, this way relies on complex and time-consuming in vivo and ex vivo approaches, it is tedious and time consuming. It is, however, unavoidable.

  4. The other poll on the question of the reality of VSELs, also being conducted right now, is the stock market, where NeoStem’s shares are down a bruising 16% today on news of the Weissman article.

    1. Bill- I liked Irv’s article. Interestingly, StemCells, Inc (Irv’s company) had a spike in trading on the 23rd and 24th. Investors seem to be reading the literature…whatever will they think of doing next?

  5. Pingback: Research Report on existence of VSELs in BM

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