Thursday, May 16, 2013

New technique could prevent the immune system from rejecting transplanted cells or organs

Mark Anderson, MD, PhD, left, and Matthias Hebrok, PhD
In what could be a critical step for developing cell transplantation therapies, CIRM grantees at UCSF have managed to turn embryonic stem cells into functioning tissue from what might be the smallest and most easily forgotten organ of your body -- the thymus.

Although the thymus is small, it plays a big role in our immune system, helping produce the white blood cells our body needs to fight off infections and prevent autoimmune reactions.

In this study, published online in the May 16 issue of Cell Stem Cell the CIRM-funded researchers took some human embryonic stem cells and, using what they describe as “a unique combination of growth factors,” managed to engineer them into becoming thymus tissue. One of the lead authors on the paper, Mark Anderson, carried out the work with a Transplantation Immunology award from CIRM. This round of awards was specifically intended to find new ways of overcoming immune rejection of stem cell-transplantation therapies.

In a news release from UCSF about the work, the researchers said:
“The achievement marks a significant step toward potential new treatments based on stem-cell and organ transplantation, as well as new therapies for type-1 diabetes and other autoimmune diseases, and for immunodeficiency diseases.”
In organ transplants for example the immune system often attacks the new organ, requiring patients to take powerful anti-rejection medications that can have difficult side effects. If researchers can coax stem cells down two different paths, at the same time, one group could become thymus tissue and the other could form a replacement organ. If both the thymus tissue and organ were then transplanted into a patient the thymus tissue could help modify the immune system, prevent it attacking the new organ so the patient would not need immunosuppression medication.

That’s a long way down the road of course and so far this work has only been done in mice, and the researchers caution that even there only about 15 percent of the cells were successfully converted to thymus tissue. Nonetheless they remain optimistic that their findings. The UCSF release quotes Anderson as saying:
“We have now developed a tool that allows us to modulate the immune system in a manner that we never had before”

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