An Australian girl spontaneously switched blood groups and adopted her donor's immune system following a liver transplant in the first known case of its type, doctors treating her said Thursday.
| I don't know enough about the subject to actually have an opinion, but it sounds like if the girl's adopted the donor's immune system she wouldn't need anti-rejection drugs? Doc Steve, does that make sense? If so, it'd be a damned significant story. |
Demi-Lee Brennan was aged nine and seriously ill with liver failure when she received the transplant, doctors at a top Sydney children's hospital told AFP. Nine months later it was discovered that she had changed blood types and her immune system had switched over to that of the donor after stem cells from the new liver migrated to her bone marrow. She is now a healthy 15-year-old, Michael Stormon, a hepatologist treating her, told AFP.
If confirmed this is significant.
Your red blood cells are made by cells in the bone marrow. Stem cells there (these can become anything) become committed to making red cells, or various types of white cells, or platelets, and then through a series of steps mature to whatever they're supposed to be. The details are interesting if you're a hematologist. Point is, you have stem cells in the marrow that serve as a reservoir for new blood cells.
For example, when we do a bone marrow transplant, we take bone marrow cells from patient A and put them into patient B (or from patient A and back into patient A after some big chemotherapy). After a period time the stem cells repopulate the marrow and churn out new blood cells (you hope).
Previously it was thought that these stem cells developed during embryogenesis and you had them for life. They were in one spot and they committed themselves to making specific kinds of mature cells. What we're learning, more and more, is that stem cells are very 'plastic': not only can they commit to being whatever they're supposed to be, but they can commit to be cells we didn't think they could commit to being, and they can replace other pools of stem cells that we didn't think they could replace. And furthermore, we're realizing that many organs have their own small pools of stem cells, and they can circulate and go to other organs.
As one example, the whole idea of stem cell infusion therapy for failing hearts is that you take bone marrow stem cells, clean them up, put them into the coronary circulation, and they'll settle in the heart and commit to being new heart muscle cells. That's in the pilot stage but it looks like it's really going to work. Cool.
Another example: really cool work done by a colleague of mine looks at how bone marrow stem cells circulate to the lungs and then help to repair damaged airways.
So what happened here was that a few (and you only need a few) stem cells from the donor liver circulated to the bone marrow. They then committed to being new red blood cells (and perhaps other cell lineages). Now how that happened without provoking a graft-versus-host response is the real story here. [Note: Ed in comments is correct: while the two blood types, donor and recipient, are different, they had to be compatible or else you would have provoked an agglutinin reaction].
Figuring that out means that we might (for example) take my healthy stem cells and use them to repair your damaged organs, or vice versa. If we can do that without provoking an immune response it opens up huge possibilities.
And it means we won't ever need embryonic stem cells; we can use adult stem cells to make whatever we need. That's very significant both scientifically and politically. |
Stormon said he had given several presentations on the case around the world and had heard of none like it. "It is extremely unusual -- in fact we don't know of any other instance in which this happened," Stormon told AFP from the Children's Hospital. "In effect she had had a bone marrow transplant. The majority of her immune system had also switched over to that of the donor."
An article on the case was published in Thursday's edition of the leading US medical journal The New England Journal of Medicine. Doctors who treated Brennan say she is now only under treatment as an outpatient and are interested to know if the case could have other applications in transplant surgery, where rejection of donor organs by the recipient's immune system is a major hurdle.
Stormon said it appeared that Brennan may have been fortunate because a "sequence of serendipitous events", including a post-transplantation infection, may have given the stem cells from her donor's liver the chance to proliferate. The task now was to establish whether the same sort of outcome could be replicated in other transplant patients, he said. |