Stricter standards for telling stem cells apart

Readers of this blog are frequently reminded that not all stem cells are created equal. This post is a bit wonky but it seems important to take note of an international effort to add rigor to defining one type of stem cell, the mesenchymal stem cell (MSC).

Clinical trials testing MSCs make up the majority of experimental therapies registered at the federal web site clinicaltrials.gov. These stem cells, which can be harvested from bone marrow or fat tissue, can be matured into bone, cartilage, blood vessels and other connective tissue, as well as more fat. But many of the clinical trails hope to show therapeutic benefit through another trait of MSCs. They release numerous proteins that seem to regulate inflammation and other behaviors of cells around them.

Even as they are being tested in everything from heart and brain injury to Crohn’s disease, debate continues on what really constitutes an MSC. The working group has scientists, industry experts and government representatives. It hopes to develop guidelines for research journals that will introduce some consistency in research reports, with each paper citing clearly where the cells were harvested, how they were grown in culture, and what percent have proteins on their surface that indicate they are really stem cells. It also hopes to establish at least one reference line of MSCs that researchers and companies can use to compare the traits of their cells.

The news section in Nature ran an article discussing the effort today. It quotes several members of the working group, including Pamela Robey of the National Institutes of Health:

“Most of the MSC biology is not rigorous. Other stem-cell biologists tend to look down their noses at the field.”

With so much of the stem cell industry—and so much patient hope—wrapped up in MSCs, this effort to add clarity to the field seem welcome, and perhaps overdue.

Our grantee, Irving Weissmann, gives a primer on the different type of stem cells in this video.

Don Gibbons

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