Bringing embryonic stem cell transplants closer to reality by quieting the immune response

A novel way of suppressing the immune system could make transplants of human embryonic stem cells a clinical possibility, according to new research by Stanford stem cell scientists.

Human embryonic stem cells (hESC) offer a tantalizing prospect for new therapies, but first we have to figure out how to get them past our immune system’s defenses. Stem cell scientists had initially thought embryonic stem cells might fly under the immune system’s radar, but a few years ago, they were surprised to find that, much like organ transplants, hESC provoke a rapid response when transplanted into a mouse’s body. When transplanted into a mouse, hESCs all died within a few days, according to previous work by the same team at Stanford, led by Joseph Wu.

But in a study published last week in the scientific journal, Stem Cells, the team used a pair of antibodies that blocked normal T-cell activation – the cells responsible for mounting the attack on foreign particles. This method worked better than the drugs traditionally used to suppress immune responses to organ transplants.

But unlike organ transplant drugs, which often need to be taken for the rest of a transplant recipient’s life, the dual-antibody treatment for hESC transplants was only needed for about a week.

On their blog, Stanford quoted Wu talking about the issue of getting the body to accept a transplant of cells derived from embryonic stem cells:

“Regenerative therapies hold great clinical promise, particularly for patients with damaged hearts and end-stage heart failure. But, surprisingly, promoting long-term stem cell graft acceptance is a much more formidable task than is supporting host acceptance of a vascularized solid organ such as a heart.”

These initial results are good news, but much more work is needed to find out if this treatment will work the same way in people as it does in mice. If the technique is effective in humans, it will help advance Wu’s ongoing work developing stem therapies for heart disease.

CIRM funding: Joseph Wu (DR2-05394, TR3-05556)

Rina Shaikh-Lesko

Learn more about the California Institute for Regenerative Medicine