CRISPR Cuts the Scientific Community in Two

Posted by Cole McElmurray

Much ado has been made about CRISPR, the enzyme complex that can edit and remove DNA from cells. Most recently, a team of scientists in 2017 led by Dr. Shoukhrat Mitalipov at Oregon Health and Science University published results where they used CRISPR to remove a gene that caused heart disease in human embryos. Mitalipov found that the enzyme complex did not use the sample DNA that the scientists had provided to repair the break in the DNA, but instead copied and used the healthy gene that was found elsewhere in the cell. Proponents of CRISPR say that the gene editing technology can be used to remove genetic mutations in human fetuses that would otherwise put them at risk for genetic disease and conditions, but others take the view that CRISPR is more trouble than it’s worth, as Megan Molteni reports for Wired.

Figure 1. The method by which CRISPR cuts and edits DNA. 

Opposition to Mitalipov’s findings was swift. Dr. Dieter Egli from Columbia University conducted research of his own on CRISPR. After three years, he has found evidence that seems to contradict Mitalipov’s research. Egli’s team injected CRISPR into sperm cells that were positive for a gene that causes blindness. After the sperm was used to fertilize eggs, the chromosomes of the embryos were looked at. It was found that the offending genes had been removed, but nothing had been put in their place. Large sections of missing DNA can cause major and adverse health effects to humans, such as disease, cancer, or death of the embryo, even more so than the mutated genes that CRISPR can remove.

Gene editing in human embryos also brings up major ethical concerns. Egli and his team were forced to find outside funding for their experiments because the US Congress will not fund experiments on viable human embryos, and the United States and 75 other countries ban any experiments that involve establishing a pregnancy with a genetically-modified embryo or fetus. The World Health Organization has recommended an immediate stop to experiments that would result in births of genetically modified humans. He Jiankui, the controversial figure who claims to have performed CRISPR experiments on embryos that were carried to term in China, was found guilty of a breach of medical ethics in late 2019 and sentenced to 3 years in prison.

This article is not exactly positive about science and chemistry, and seems to try to paint a picture of “mad science”. It’s meant to show the reader that sometimes scientists can go too far in their pursuit of research and progress. The article uses fear tactics by focusing on genetically modified fetuses and negative health effects that can occur from CRISPR, as well as bringing up the lurid story of He Jiankui. The article is remarkably light on actual chemistry facts. It does not even bring up that CRISPR is an enzyme complex, leading some readers to make the conclusion that it is some sort of machine or tool. While it makes mention of CRISPR “cutting” DNA, it does not mention the mechanism by which it does so. The article deliberately keeps the chemistry light in order to not bore a lay reader and to focus on the ethics of CRISPR instead of the science.