Trials in gene editing in humans about to begin in 2017
The biotechnology company Editas hopes to begin clinical trials using the latest gene editing technique on human subjects in 2017, according to the company’s CEO Katrine Bosley.
The CRISPR/Cas system is a prokaryotic immune system that confers resistance to foreign genetic elements such as plasmids and phages, and provides a form of acquired immunity.
It consists of regularly repeated DNA sequences, interspersed with DNA of certain viruses that the bacterium has held onto in case of future confrontation. These then serve as a guide for enzymes called CRISPR-associated proteins (Cas), which are then able to attack these viruses when they invade, cutting their DNA.
CRISPR enables scientists to edit genomes with greater precision and efficiency than ever before, by cutting DNA sequences at specific points and inserting new material. The technique was first used in 2012, and since then, several studies have pointed out its potential to revolutionize biological research and molecular therapeutics.
Editas now intends to use CRISPR to treat a rare form of Leber Congenital Amaurosis (LCA), an inherited condition that causes severe visual impairment. The precise gene mutation is already known and the cells requiring correction are easily accessible. By amending the error, the genes should then function correctly, thereby curing the disease. Editas aims to achieve this by injecting an assemblage of viruses containing CRISPR gene sequences into patients’ retinas, which will then cut the intended gene at a specific location.
While the technique represents a huge step forward for gene therapy, it has also raised ethical concerns and fears of the risks of generating unknown side-effects. This debate peaked earlier this year when Chinese scientists used CRISPR to genetically modify human embryos. Although the scientists deliberately used embryos that were not capable of giving life, the controversy they caused highlights the moralistic minefield that researchers using CRISPR on humans will have to negotiate. Before proceeding to human trials, Bosely insists that Editas will first have to conduct more studies in the laboratory and on animals.
