The CRISPR gene editing technology has transformed the research lab, and this powerful tool is now making its way into the clinic. So far, three different human diseases have been successfully treated in patients with specialized CRISPR methods. Now researchers have used CRISPR to develop a way to repair damaged neurons. This research may eventually open up treatment options for neurodegenerative disorders like ALS (amyotrophic lateral sclerosis) and spinal muscular atrophy.
Neuronal damage triggers the production of repair proteins in these damaged cells. But these repair mechanisms often fail in neurodegenerative disease. The RNA molecules encoding for the restorative proteins don't get to the right place, and the neurons are permanently damaged.
Scientists were able to find a way to deliver that important RNA to specific places in neurons. Once there, they can repair and even regenerate parts of the neuron, in a major breakthrough. This NIH-funded work will hopefully pave the way for so-called spatial RNA medicine. With the continued grant funding, this effort could lead to treatments not only for neuronal disorders, but also for injuries. The research has been reported in Nature.
“For the first time, we’ve harnessed the power of CRISPR technology to create a precise spatial ‘zip code’ that delivers RNA molecules exactly where they’re needed within cells,” said senior study author Stanley Qi, an associate professor at Stanford University, among other appointments. “Imagine being able to specifically target damaged sites within a neuron, repairing them, and promoting their regrowth; this is what our technology achieves.”
The molecules that RNA encodes for are very important to understand and study. But the location of that RNA is also apparently crucial. Mutations could interfere with the RNA's movement.
“Therapeutic RNA can’t help if it doesn’t get to where it’s needed,” Qi explained. “We wanted to create a technology that could reliably move RNA to where it needs to function.”
The investigators used CRISPR along with an enzyme called Cas13. While this enzyme can cut DNA, the researchers altered it.
“Cas13 naturally acts like a pair of scissors, but we engineered it to act like a mailman instead,” Qi said. “Then we can tell it to carry the RNA from one precise location to another.”
In this work, the scientists combined Cas13 with signals that can direct it to certain locations, so it takes accompanying RNA molecules to the right place. Different locations can be targeted with different tags. The investigators called this method CRISPR-TO.
CRISPR-TO was then used in the lab. The researchers added it to mouse neurons in culture, and it delivered RNA molecules to neurites, a part of the neuron that synapses with other neurons. The team screened various RNA molecules to see if any triggered neuronal growth. There were a few good candidates; one even increased growth in neurites by 50% within one day. Now, more molecules are being evaluated.
“We are discovering more RNA targets that could promote neurite outgrowth and regeneration,” said lead study author Mengting Han, a postdoctoral scholar in the Qi lab. “We’ve added a new tool to the CRISPR toolbox, using it to control RNA localization inside the cell. This has never been achieved before and, importantly, it opens new therapeutic directions for treating neurodegenerative diseases.”
This tool could also eventually help improve RNA-based medicines to make them more precise and safe.
“This potential excites us tremendously,” Qi said. “It’s not enough for a molecule to just be in the cell. We need it to be in the right location at the right time. With our precise, programmable technology, you can target any RNA in any type of cell and bring it to the site of need in the body.”
Sources: Stanford University, Nature