October 20, 2020

The Niche

Knoepfler lab stem cell blog

Do human Very Small Embryonic-Like Stem Cells (VSEL) exist as a normal population of actual stem cells?

NeoStemSupposedly there is a type of normal adult stem cell that intrinsically possesses many of the same properties as embryonic stem cells (ESCs).

No reprogramming needed. No blastocysts needed.

These reportedly amazing cells, called Very Small Embryonic-Like Stem Cells (VSELs), can in theory be isolated from umbilical cord blood (UCB) or even bone marrow. Yet they are pluripotent like ESCs. They seem to be present in mice and possibly in humans.

Wow, you say, VSELs seem like the best thing since sliced bread?

No ethical dilemmas. No need for ESCs or maybe even iPS cells.

The Vatican and associated adult-only stem cell researchers proclaim VSELs to be very exciting.

VSELs sound almost miraculous….

There is, however, a problem.

Many scientists in the stem cell field do not believe that VSELs exist as a real, normal population of actual stem cells in human beings.

I myself have never studied VSEL in mice or humans so I do not have direct knowledge about them one way or another, but there are reasons for having some serious doubts about them.

There are 45 articles in Pubmed with the name of these cells in the title, but by an unusually small number of independent groups and mostly not in high profile journals.

One article on VSEL this year entitled, Very small embryonic-like stem cells purified from umbilical cord blood lack stem cell characteristics, seems rather discouraging for human VSEL believers.

The authors conclude that human “VSEL cells are an aberrant and inactive population.”

The super blogger and scientist Alexey Bersenev tackled the question of human VSELs on his blog here earlier this year and discussed the above paper, quoting the authors:

It is therefore questionable whether UCB VSEL cells should be termed “stem cells” at all.

Another recent article, a perspectives piece written by a team led by Rüdiger Alt, digs deeper into VSELs from a broader view.

Despite the controversy over VSELs, particularly in humans, this past week interestingly it was reported by Nasdaq that Vatican-affiliated stem cell biotech, NeoStem, received a $1.2 million NIH grant to study human VSELs. It is grant number 2R44DE022493-02A1, from the National Institute of Dental and Craniofacial Research (NIDCR). You can read about the grant here on the NIH database.

The Nasdaq piece (a NeoStem press release?) says:

Dr. Robin L. Smith, Chairman and CEO of NeoStem, added, “We are very excited about this important step of funding for what will be the first human clinical study for our VSELTM technology. Not only will this study expand our knowledge of how autologous cell therapy can treat periodontitis and other bone defects, but it represents a milestone for NeoStem as we move our development of VSELTM technology beyond animal models and into the clinic, paving the way for other potential VSELTM trials.”

The grant funds work on using human VSEL to make human bone, but it seems the stem cell field is unclear if human VSEL really exist as a normal stem cell population….

So what is going on here?

I’m not sure.

We have more questions than answers, but some NIH grant reviewers apparently seem to have faith.

Maybe they’ve seen data that the rest of the stem cell field hasn’t?

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