Mixing the stem cells of an organ recipient with those of the donor could help to keep the body's picky immune system from rejecting transplants.

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One of the greatest challenges in medicine is the need for replacement organs. Every 10 minutes another person's name is added to the national organ transplantation waiting list, the length of which now exceeds 100,000. Eighteen of these people die each day. Those who are fortunate enough to receive an organ often have to take immunosuppressive drugs for the rest of their lives, thus making them more vulnerable to other infections, and even then their new organs may gradually be rejected by their immune system.

One potential way to overcome this problem is through the creation of a chimeric immune system by mixing the immune (hematopoetic) stem cells of the recipient with that of the donor. As explained in last week's issue of Science Translational Medicine:

According to Greek mythology, the Chimera was a fire-breathing creature made of parts from different animals: the body of a lioness, a snake's head at the end of the tail, and the head of the goat. Sightings of this fearsome beast portended any of a number of terrible disasters. In the context of organ transplantation, a "chimera" can indicate both desirable and disastrous outcomes. For example, hematopoietic chimerism, in which the immune cells in the graft recipient come from both the host and the donor, may promote graft tolerance, but may also cause graft-versus-host disease (GVHD), in which the donor immune cells attack the healthy tissue of the host.

The underlying problem behind rejection and GVHD -- both of which shrink the potential donor pool -- is matching. Now, a novel procedure has come one step closer to overcoming the matching problem and achieving transplantation tolerance. In an exciting, albeit small, study the University of Louisville team transplanted mismatched, unrelated donor kidneys into eight patients along with a mix of donor hematopoetic stem cells and a special population of tolerance-inducing facilitator cells (FCs). These FCs have been shown in animal models to improve engraftment (acceptance of the graft) and avoid GVHD. The results and potential meaning are well-summarized by Science Translational Medicine:

Five of eight kidney transplant recipients exhibited durable chimerism and were weaned off immunosuppressive therapies by one year after transplantation, with no signs of GVHD or engraftment syndrome. If confirmed in larger patient cohorts, this approach to transplantation could free some patients from the difficulties associated with lifelong immunosuppression and add transplantation as a viable option for patients for whom no matched donors exist.

An editorial written in STM about the study says that this procedure "may potentially have an enormous, paradigm-shifting impact on solid-organ transplantation" and that "few transplant developments in the past half-century have been more enticing than these that put transplantation tolerance within our grasp." This editor followed up with the primary investigator of the study, Dr. Suzanne Ildstad from the Institute for Cellular Therapeutics at the University of Louisville, to ask about the future of the procedure as well as other applications that are being explored:

Your paper refers to applications "not only in sold organ and cell transplant recipients but also for ... hemoglobinopathies, inherited metabolic disorders, and autoimmune diseases." What other applications are currently being explored using this novel chimeric approach?

We are currently working on applying this procedure to sickle cell disease, thalassemia, metachromatic leukodystrophy, and in the near future, type 1 diabetes.

See the original post:
A Chimeric Immune System: Fixing the Problem With Organ Transplant

CLEVELAND, Ohio -- Talk about a potentially major game changer for a woman and her eggs.

For the first time ever, researchers have proven the existence of egg-producing stem cells in the ovaries of humans.

The breakthrough throws open the door -- albeit years down the road -- to the possibility that women in their 30s and 40s, whose fertility is on the decline, could replenish their dwindling egg supplies.

Researchers at Massachusetts General Hospital in Boston used a new technique to pull stem cells from the ovaries of six women in their 20s and 30s whose ovaries had been removed as part of gender reassignment surgery.

When grown in the lab, those stem cells produced oocytes, which are immature egg cells that have not yet developed into an egg.

A video on the journal's web site does a good job of describing the research in layman's terms.

"These cells, when maintained outside the body, are more than happy to make eggs on their own," Jonathan Tilly, a professor of obstetrics, gynecology and reproductive biology at Harvard Medical School and chief of research at the Massachusetts General Hospital Vincent Department of Obstetrics and Gynecology, said in a video interview.

"And if we can guide the process correctly, I think it opens up the chance that sometime in the future we might get to the point of having an unlimited source of human eggs. . . . It would rewrite, essentially, human assisted reproduction," he said.

The findings of the research team led by Tilly are in the March issue of the journal Nature Medicine.

Fertility specialists view these findings not only as exciting but also as a complete paradigm shift. And rightly so, since conventional wisdom has long dictated that a woman is born with all of the eggs she'll ever have. And when they're gone, they're gone.

The rest is here:
Stem cells might one day form human eggs, research finds