The most common type of stem cell used in clinical trials today is the mesenchymal stem cell (MSC) found in bone marrow and fat. The federal web site, clinicaltrials.gov lists a few hundred MSC trials. A pair of news stories on the web this morning detail why MSCs are so versatile, but also why they have limitations.
Internal Medicine News posted a summary of the presentation CIRM grantee Jan Nolte of the University of California, Davis, made at the World Stem Cell Summit last month. She noted that when the problem is tissue damage, MSCs secrete factors that stimulate the growth of new blood vessels, recruit the patient’s own organ-specific stem cells to the site of damage, and reduce the inflammation in the area to promote healing.
But she also noted that MSCs do not make an organ or grow new replacement tissue themselves, that we need embryonic stem cells to do that. She provided a great quote on what MSCs do well:
They can become paramedics or supercharged drugstores to take these factors that we want them to deliver into the damaged or dying tissue.
The second news report through the service EurekAlert gave further evidence for one method MSC’s lend a helping hand, and a possible method for strengthening their grip. Earlier reports have suggested that MSCs may help cells by transferring some of their mitochondria to the damaged tissue. Since mitochondria are the energy houses that help power cells, a few extra should help damaged tissue.
Now, a team at CSIR-Institute of Genomics and Integrative Biology in Delhi, India, has published in EMBO a study that showed that in the presence of a certain protein the MSCs were more efficient in lending damaged cells needed mitochondria. They engineered MSCs to produce more of that protein and sure enough, in a mouse model of asthma, they had more therapeutic benefit. The news service quoted a member of the team, Anurag Agrawal:
The introduction of mitochondria into damaged cells has beneficial effects on the health of cells and, in the long term, we believe that mesenchymal stem cells could even be engineered to create more effective therapies for lung disease in humans.
I believe combining the power of stem cell science and gene therapy is going to produce some of the most dramatic early success stories in our field. So, it is nice to see more of the rational for this explained in public venues.