Recently, two beagles were born in South Korea that had been cloned using CRISPR gene editing on skin cells. In the past, beagles were created using CRISPR gene editing on fertilized eggs, but this was the first time that beagles had been cloned using the gene editing technique in somatic (non-reproductive) cells. 

The advantage of performing gene editing in somatic cells is that when gene editing is done in fertilized eggs, it is more likely to affect other traits besides the specific mutation that is being targeted.

Using CRISPR Gene Editing to Alter the DNA in Beagle Skin Cells

The scientists involved wanted to find a new way to treat genetic disorders. They used purebred dogs because these dogs, after having been inbred for generations, are especially susceptible to genetic mutations that cause disease.

In this experiment, the scientists targeted a gene that produces a protein called DJ-1 that is associated with Parkinson’s disease, Alzheimer’s disease, and stroke. They used CRISPR gene editing in beagle skin cells to alter the DJ-1 gene to prevent it from making the DJ-1 protein. 

Creating Embryos From the Altered Skin Cells

To produce embryos, the scientists took the skin cells that had been successfully genetically edited and put them next to egg cells that had their DNA removed. They used pulses of electricity to fuse the skin and egg cells together.

That procedure produced 68 embryos. They were implanted in six beagle surrogate mothers. From that, two puppies were born.

Results of the Experiment

The experiment is successful, at least so far. The dogs produced less or none of the DJ-1 protein and, at 22 months old, show no abnormalities. The scientists are still monitoring the progress of the dogs because the DJ-1 diseases are age-related and could show up later in the dogs’ lives.

Scientists have been cloning animals from somatic cells since 2005. But the recent use of CRISPR and similar gene editing technologies has allowed scientists to target specific genetic sequences. In previous studies, scientists used the new techniques to increase disease resistance in pigs and cows, increase the productivity of cashmere goats and pigs, and create hornless dairy cattle.

How CRISPR Gene Editing Works

The CRISPR editing system uses an enzyme that cuts DNA, along with a guide molecule that finds a specific point on the DNA strand. The guide molecule takes the complex to the site of the gene that scientists want to delete or alter, and (if all goes well), the enzyme cuts the DNA in precisely the right place. The cell’s natural healing mechanisms then come into play and repair the cut.

Warnings From Scientists

The CRISPR editing technology has proven very successful in a variety of studies, including in preliminary clinical trials in humans for treating genetic diseases including sickle cell anemia. However, some scientists believe that the technique is less precise than previously thought, doesn’t always target the correct place on the genome, and could cause unexpected and dangerous mutations. They are especially concerned about the potential dangers of using CRISPR on human embryos, which has already been done illegally in China.

Potential Benefits From This Research

This experiment shows that CRISPR can be used to delete a harmful mutation in purebred dogs. If the experiment continues to be successful, it will show that CRISPR and similar genetic editing tools can be used to correct disease-causing mutations in cloned dogs using somatic cells with altered DNA. These kinds of studies can also provide animal models that can help scientists better understand how to prevent similar diseases in humans.