Stem Cell Transplants to Cure AIDS?

I am always concerned when the press run stories of cures. The science may well be interesting but I feel compassion for those who have hopes raised.

There was much publicity recently about the man who was "cured of HIV" by a stem cell transplant. He was unfortunate enough to have leukaemia. And he was HIV positive. In the process of treating his leukaemia in 2007, with a procedure known as a stem cell transplant, it appears that the AIDS virus was cleared from his immune system and he remains healthy. It is possible though that HIV still lurks in his brain, beyond the reach of his immune cells.

So does this news offer hope for those who have to take a daily cocktail of antivirals to keep their HIV infection in check?

The stem cells that make up the red bone marrow produce the full range of "white blood cells" that, in turn, make up the immune system. Leukaemia is a disease of the bone marrow - one type of stem cell turns cancerous and the mix of immune cells is thrown wildly off balance, with fatal consequences. Stem cell transplants have superceded "bone marrow transplants". These days the stem cells can be harvested from the donor's blood using a process similar to a single session of dialysis.

If normal chemotherapy fails to cure a case of leukaemia, the only solution is to use stronger drugs to kill off the bone marrow. Then the patient is given a transplant of healthy stem cells from a donor. This rebuilds the immune system with cells that are genetically matched to the donor.

There are many risks and difficulties. While waiting for the transplant to start working, the patient's immune system dwindles to almost nothing for a few weeks, leaving them highly vulnerable to infection. Any pre-existing infections would run riot - so that probably excludes anyone suffering from AIDS. The other problem is finding a suitable donor. We have all heard of people who need a bone marrow transplant but cannot find a suitably matched donor. The problem is the huge variety of possible tissue types. The tissue types of patient and donor need to be very similar if they transplant is to work. Rejection can bring life-threatening complications. So a stem cell transplant is a risky, expensive, treatment-of-last-resort, that is only used in a minority of cases of leukaemia.

 In this remarkable case the patient was able to receive a transplant from another unusual person - someone who had a natural immunity to HIV. These people are extremely rare. So it was not necessarily the transplant that cleared the virus - it might have been the particular genetic makeup of the donated cells.

 So to use this as a treatment for HIV you would need a reasonably healthy patient who has not succumbed to any AIDS-related infections and a matched donor, with a very special, very rare immune system.  

This was not an experiment. An imaginative doctor identifying an opportunity and tried something new. It could well turn out to be a one-off case, thought provoking for scientists, but for the time being (sadly) a million miles away from being a realistic prospect as a treatment for HIV. A cure for HIV may someday be found, but it will result from painstaking research and not from stem cell transplants as we know them today.

Mouse Immune System Responds to Music

It is not that surprising that music has been shown to reduce stress and distress in some human patients. But who would have thought that mice would be affected by music? But it seems that mice produce and respond to music. According to recent research, male domestic mice (and other species) sing, like songbirds, to attract a mate. Strange to think they might be warbling away beneath the floorboards. Fortunately their song is not audible to humans otherwise it might keep us awake.

Musical mice are also in the news due to recent Japanese research that involved playing opera and Enya to mice that were being subjected to heart transplants (Masateru Uchiyama et al, 2012).You would think the idea for this research might have been a bit of a wild card - but indeed someone's hunch paid off in terms of some interesting results. (But yes, this was tough on the mice and I don't think if I was on the ethics committee I'd have been talked into approving this one.)

Transplant survival increased in the mice that were treated to the non-stop opera (but not the new-age Enya) and there were significant changes in some key immune cells and molecules.

So should we conclude that music boosts your immune system? Not at all - increased transplant survival indicates less rejection - and therefore a less active immune response.

Does this research have an application in terms of human health and recovery? Again, I don't think so. The musical likes and dislikes of mice and humans might, after all, be different. Not to mention the musical preferences of their immune systems.

Should someone be trying to repeat this research on humans? Again the answer is no. You would have to persuade transplant patients to volunteer to put up with non-stop noise (classical, new-age, or just a high pitched sound) for a week before or after their operations. A bit of a non-starter I'd say. And humans are given anti-rejection drugs which would muddy the waters, to say the least. 

This is the kind of research that raises lots of questions, many of which may never be answered. But it does highlight that, even in mice, the interaction between the brain and the immune system is more complicated than we can begin to imagine.