Back at Gene Therapy

I haven't been to the Gene Therapy Advisory Committee since February. I attended the last meeting of the year yesterday, and I took some time to get back into the swim of things. There were three proposals for us to look at. The first one dealt with the problem of cytomegalovirus (CMV)in transplant recipients.

CMV is a herpes virus; most of us get it, usually subclinically, but it remains in a dormant form ready to reactivate if ever the immune system fails in its surveillance. This is likely to happen following a marrow transplant, especially when the donor stem cells come from a seronegative individual. There are drugs that are fairly effective like gancyclovir and foscarnet, but these are themselves toxic. The idea here was to transfect the donor cells with a T cell receptor that reacts with CMV antigens and infuse these into the recipient as a virus specific donor lymphocyte infusion.

The second idea was to deal with Parkinson's disease. This is another disease for which there is a treatment, but it becomes unsatisfactory as time passes. L-Dopa gets converted into dopamine which is a neurotransmitter in the substantia nigra in the brain. As the cells in the substantia nigra die there are too few to do the conversion, no matter how much L-Dopa there is. The idea here is to transfect other cells in this part of the brain with the genes to make the necessary enzymes to do the conversion.

The other submission builds on the progress made in both the UK and the USA in injecting genes directly into the retina of the eye for some forms of retinitis pigmentosa. In theory this technique should work for any single gene disorder that causes blindness. One such is choroideraemia which affects 1 in 50,000 people. The missing gene is REP-1 and this ought to work.

We have also been given the responsibility for supervising stem cell research. Thus far we have not had a proposal to consider. It may be that we will be able to see the successful and safe generation of pluripotent stem cells from the patient's own fibroblasts, before I am forced to declare my opposition to embryonic cell treatment. The one company that looked like being able to go forward with an embryonic cell line seems to have been stymied over regulatory issues.