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For the last several years CRISPR gene editing has been touted as a possible solution to everything from creating new biofuels, to eliminating malaria in mosquitoes, to curing a whole host of human genetic diseases. Now it looks like scientists may have discovered an even better tool, one they’re dubbing LEAPER.
CRISPR’s promise
CRISPR gene editing broke onto the scientific scene in the early 2010s. In fact, Science Magazine hailed it as a breakthrough of the year in 2015. The medical technology allows scientists to reach into an organism’s DNA and literally cut out out unwanted genes, or replace them with new ones.
In humans, such genetic splicing offers hope for eliminating incurable diseases including muscular dystrophy, AIDS, cystic fibrosis, cancer, and even blindness. However, CRISPR editing involves multiple processes and can cause unwanted cellular immune responses. Basically, CRISPR editing uses a modified virus to do the cutting and replacing in human DNA. For instance, it often uses the staphylococcus virus to get into the cell. Not realizing why the virus is there, and assuming they are being attached, the cells fight back. As a result, the CRISPR “cure” might come with some side effects.
LEAPER: A better way?
LEAPER, a technology just announced by scientists at China’s Peking University, uses a similar approach to CRISPR and promises similarly grand results. But LEAPER involves fewer steps than its predecessor and doesn’t seem to risk the same immune system responses.
The main difference is in where the two systems work on our genetic code. Early versions of CRISPR worked directly on our DNA. More recent versions, specifically CRISPR Cas13, work instead on RNA, and REAPER does as well.
Think of DNA as the home of our genetic code. It resides in the nucleus of all living cells and tells those cells how to behave. The DNA in our human cells, for instance, dictate everything about our physiology, from our hair and eye color to our height, to how many freckles we may have, to whether or not we are likely to develop cancer in our lifetimes. RNA, on the other hand, is a messenger, a go-between between DNA and the proteins that do the work in our body. DNA contains the master code, it imprints that code on RNA, and RNA then delivers the instructions to the proteins.
Because it is the messenger, not the source, RNA contains a somewhat less stable version of our genetic code. RNA has only one strand, for instance, where DNA exists in a double-stranded helix. However, RNA is more easily accessible. It can, for instance, move in and out of a cell. And it seems to be easier to edit, which is why it has become the primary location for genetic editing in the most recent medical lab experiments.
However, even the CRISPR that works on RNA, Cas13, requires a modified virus to find its way into the RNA. LEAPER, in contrast, accesses RNA more directly, through a single component known as arRNA. This makes LEAPER easier to use. It also eliminates the immunity issues that come with CRISPR.
When will it be ready?
LEAPER has shown strong early promise, and the scientists who pioneered its use believe it could essentially cure every known hereditary disease. However, hurdles remain. So far, for example, LEAPER has only cured cells in the laboratory. Cells taken from people suffering from Hurler’s Syndrome, a rare genetic disease seemed completely cured through LEAPER technology, but that’s very different from cured cells in a human body.
Ernst Wolvetang, with the Australian Institute for Bioengineering and Nanotechnology, warns that at any step along the way problems could develop with LEAPER technology. It may be, for instance, that LEAPER’s simplified approach to accessing RNA could result in unexpected and unwanted changes to a person’s genetic code.
The next stage of development involves research and testing in animals, meaning it will be some time before LEAPER can actually be used on humans. Still, we may already be in reach of a day when some of mankind’s worst diseases will finally be cured.