“Mesenchymal stromal cells: There is Life in Death” – Layman Seminar Summary

_Pixabay.com

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Scientific summary and references can be found here

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Mesenchymal stem cells, short MSC, are a group of cells from different origins like bone marrow or umbilical cord blood. They are called “stem cells” because they can change into other cell types under the right conditions. But the power of MSC goes beyond simple stem cell abilities!

One of the currently researched uses for MSC is stem cell therapy, for which the cells are transferred into a sick person and help fight the disease. Transfused MSC affect a patient’s immune system, as they specifically reduce inflammation and help treat rejections of organ transplants.

Bone marrow transplants are a special case of transplant, because immune cells from the donor are present in the patient’s body as a result. This can result in “graft versus host disease” (GvHD), where the immune cells start attacking the patient’s body, killing them if left untreated.

When patients with GvHD received MSC injections, the response among those who did respond to the treatment was fast and efficient. The results just one week after the injection could already predict the outcome of the therapy, and even a small response had a positive effect on their survival.

But why is that?

Even though MSC don’t have to match the patient as it would be the case with a blood or organ donation, they are recognized by two different types of “killer” cells, so-called cytotoxic cells, shortly after they enter the body. The cytotoxic cells don’t just kill the MSC but cause them to undergo a process called “apoptosis”, a controlled death of the cells. The dead MSC are then cleaned up by macrophages, cells that “eat” dead cells, pathogens, and other things not supposed to stay freely in the body.

As a reaction to having consumed the MSC, the macrophages start producing chemicals that affect other immune cells, either re-programming them to become anti-inflammatory or directly keeping them from causing inflammation. And because inflammation is tied to GvHD, MSC can help.

The only problem here is, that the patient needs functioning cytotoxic cells to cause the MSC to undergo apoptosis. If that doesn’t happen sufficiently or at all, the treatment doesn’t work. Prof. Francesco Dazzi and his group tried to solve this issue by inducing apoptosis outside the body, and injecting MSC already in the process of it.

What they observed were the same effects as before, production of the wanted chemicals by the macrophages and reduction of inflammation in the important areas. This discovery means that it is possible to use MSC even if the patient’s cytotoxic cells don’t respond as needed, making the treatment accessible for more people.

Overall, mesenchymal stem cells appear to be relatively safe for stem cell therapy. They only have an effect where they are supposed to, they don’t require donor-matching, and there are methods being established to grow them more easily in a laboratory. The discovery that artificially starting the process of apoptosis maintains their effectivity and reduces the criteria the patient has to meet only adds to their importance.