How our Stem Cells Can Fix our Hear t!

One of the factors affecting in the slow progress of finding a
cure for Stargardt?s is the nature of the gene responsible for this
retinal disease. Some people with the gene never develop the disease,
while others seem to develop it without the gene. Environmental and
unknown factors play a role as well.

In the future, when a patient manifests a genetic defect, doctors
hope to be able to correct it and resolve the problems it causes. Gene
therapy involves inserting a functioning gene into human cells to
correct a genetic error or to introduce a new function to the cells.
The surgeon must transplant genes rather than cells, a strategy which
miniaturizes the process by a million fold. The surgical tools are not
hand-held instruments, but trained viruses. At the 1998 conference of
the Association for Research in Vision and Ophthalmology, a report
presented just such a technique for retinitis pigmentosa (RP), another
retinal degenerative disease. Researchers showed that a virus called
Lenti could carry a new gene into mouse photoreceptors and could
prevent the photoreceptors from degenerating for six months in a mouse
model of recessive RP. That's a long time for a mouse! In another
experiment, an adenovirus was used to deliver a gene designed to
prevent the expression of an abnormal dominant gene for RP. Thus, it
appears that both dominant and recessive forms of RP are amenable to
gene therapy -- at least in mice! Before we can begin human trials of
gene therapy for retinal degenerations, the long term effects of these
viruses, including rejection, must be better understood. Like
transplantation, this approach requires delicate subretinal surgery to
place the virus near the photoreceptors and the RPE.