C. reinhardtii is a single-celled green algae whose spherical cells are about 10 microns in diameter. It is commonly found in soil and freshwater, where it uses an eyespot to sense light for photosynthesis, and swims towards it using flagella. Chlamydomonas species produce a light-sensing protein called channelrhodopsin-2, and it’s this protein that could literally restore sight to the blind.
Channelrhodopsins are light-gated ion channels. These transmembrane proteins form ion channels that change conformation in response to light, causing the channel to open or close. In Chlamydomonas, the ion channels are linked to flagella function, allowing the cells to travel towards a light source. Using gene therapy, RetroSense plans to insert the channelrhodopsin-2 gene into the retinal neurons of people suffering blindness due to conditions such as macular degeneration and retinitis pigmentosa. In human retinal neurons, channelrhodopsin-2 should excite the neurons in response to light.
This isn’t the first time Chlamydomonas has been in the news. Because it is simple to grow and its genome can be easily manipulated, Chlamydomonas is widely used to produce “biopharmaceuticals”. Such therapeutics include human papilloma virus and malaria vaccines, and even a “designer” cancer drug. It has even been considered as a clean source of hydrogen fuel because it can perform photosynthesis in the absence of oxygen, producing hydrogen as a byproduct.
Check out the following video for a summary of the research being done on channelrhodopsins and blindness.
Sources: Wired, Rice University, Wikipedia, RetroSense Therapeutics, NIH, Foundation Fighting Blindness, Business Wire, Phys.org