Will optogenetics change medicine?
It’s not just epilepsy that could be cured using optogenetics, there are a whole host of other possible uses. Isabel Christie from UCL spoke to Kat Arney about whether it could have applications in eyes...
Anabel - Absolutely. As you mentioned, the cells in the retina are already light sensitive so one of the obvious ways of trying to cure blindness would be to replace those light-sensitive proteins in defective retinal cells. So channelrhodopsin was expressed in the retina of blind mice in 2006 and in 2015, the FDA actually approved retinal targeting of channelrhodopsin expression. I understand that the first transfer of opsins to humans occurred in 2016, so I think this is a really active area of research and something to be really excited about.
Kat - Are there other tissues in the body, other tissues that need to be excited, need to be turned on that this kind of technique could be applied to?
Anabel - Yes. There’s been a lot of excitement about the idea of targeting cardiac myocyte, the heart muscle cells. Often a pacemaker can be applied to the heart with people that have heart conditions and so cardiac myocytes can be stimulated in a similar way to nerve cells.
Kat - So you could do that really precisely though, rather than just having a battery pack?
Anabel - Absolutely. As your previous was just saying, the problem with electrical stimulation is it’s like a sledgehammer, you often hit many of the cells at once. Whereas with optogenetics, you can target specific cells in a more localised way so it would probably be much better than a pacemaker in the heart as well.
Kat - And also Andrew touched on the idea of deep brain stimulation. Particularly I’m thinking of Parkinson’s disease where certain cells that are not working properly and you want to kick them into action. Would this work and is this really a good idea to use optogenetics?
Anabel - I think it’s a brilliant idea because there are already patients undergoing invasive surgery where they’re having electrodes implanted into their brain, so they are already having a very invasive process. But if you were to use optogenetics you would have to implant optic fibres into that part of the brain and, in addition to that, you would have to genetically modify those brain cells. So one of the ethical issues that we would have to deal with if we were going to start doing this in people is genetic modification of human brain cells. I think there might be some reluctance to do that.
Kat - Although we have seen great advances in gene therapy lately. We’ve seen the tools that I’ve mentioned for gene editing - things like CRISPR, which enable these techniques to be done a bit more accurately. It feels like there is a world opening up… maybe?
Anabel - Yeah. I mean I personally think if we can overcome the ethical issues associated with genetically modifying human tissue then it will lead to many applications and many exciting things, but it’s just something to consider. With deep brain stimulation, you are just implanting electrodes into the brain. This would be a two step process. I think one of the challenges is can we do gene editing in a continuous way? Can we modify these brain cells long term, not just temporarily?
Kat - It seems like a lot of exciting techniques that need to happen?
Anabel - Yeah. It’s a very exciting time for neuroscience.