Dispatches from ARVO 2013: Day 2
May 7, 2013
by Jennifer Phillips, Ph.D.
The talks I attended today were on the topics of photoreceptor cilia, Nanotechnology and Regenerative Medicine, and Stem Cell therapies. Afterward, I saw posters on a wide variety of studies related to retinal degeneration.
Brief highlights from the talks:
Nanotechnology emerged on the scene a few years ago as a new drug delivery method. The basic idea is tiny doses of a pharmaceutical agent are packaged inside a coating made of a material that will facilitate the delivery of the drug to the proper tissue. The exact nature of the material depends a lot on the tissue being targeted by the drug. In the case of ocular drugs, the big challenge is getting past all the physical, physiological, and molecular barriers that are there to protect the eye from foreign invaders. The next biggest challenges relate to regulating the dose of the drug once it gets in there, and making sure the packaging doesn’t end up causing problems once it’s tricked your security system into letting it pass through. These are complex problems that a lot of really smart people are working on, and in the fullness of time it could make any emerging drug therapies for Usher syndrome and other retinal diseases easier and more effective to administer.
Stem Cell derived cultures of photoreceptor cells and RPE cells are being used to study what goes wrong in cases of disease , and also to preclinically test emerging treatments. One interesting tidbit from this series of talks was the description of several cell lines, each containing a different retinal degenerative disease mutation, being used to reexamine the old Vitamin A/Vitamin E supplement controversy. Not surprisingly, given the previous findings, cells representing some diseases responded positively (by surviving in greater numbers, or for longer periods, than untreated cells with the same disease gene), while others responded negatively. The outcome wasn’t surprising, but the experiment served two main purposes. The first was the proof of principle that individualized stem cells (containing the exact mutations of any given patient) could be used to screen for effective treatments for individuals. The other was the acknowledgement that this testing—cultivating the disease-gene-carrying cell lines, administering the supplements, monitering the results, required lots of time, personnel, and money to complete. Personalized medicine using stem cell technology is a great goal, but it’s prohibitively costly with the current methods.
Featured Poster of the Day:
I wasn’t able to speak to the researcher presenting this poster, but there was a very nice report from researchers at the Hospital for Sick Children in Toronto. They screened a group of 23 pediatric cochlear implant patients for vision defects, and began genetic testing in those with abnormal visual function tests to look for Usher gene mutations. Of the 23 children tested via comprehensive eye exams, ERG, and visual field analysis, they found 11 kids with vision problems—45% of their total number of subjects. Genetic testing is ongoing, but preliminary results suggested that 8 of the subjects were carrying mutations in one of two Usher genes (Myosin 7A and Cadherin 23). It didn’t appear as though screening was complete, and even when mutations in these genes are found, further analysis is required to demonstrate that those mutations are actually disease causing, as opposed to just random changes in the base sequence that all of us have in every one of our genes that, for the most part, don’t cause any problems.
Be that as it may, the power of this screen is undeniable. The families of 11 kids between 8 and 14 years old learned for the first time that their children had vision problems, and that these problems might be related to the genetic cause of their deafness. This fact alone underscores the need for vision and genetic screening becoming the standard of care for children with hearing problems.
There’s much more science in the pipeline for tomorrow! I’ll see you back here then.
