Biotechnology firm 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. Speaking at the EmTech MIT event in Massachusetts, Bosley announced plans to use CRISPR to treat a rare form of blindness by editing the faulty genes that cause the condition.
CRISPR is a technology that 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, which was first used in 2012, has generated a great deal of hype, with several studies pointing 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. According to Bosley, the genome responsible for the disorder is the perfect candidate for CRISPR-based alterations, since the precise gene mutation is already known and the cells requiring correction are easily accessible. By amending this error, the genes should then function correctly, thereby curing the disease.
While it may sound high-tech, CRISPR is a natural phenomenon. It's found in a large number of microbes as part of their defense mechanism. 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 to shreds. Scientists are now able to use these proteins to splice faulty gene sequences for therapeutic purposes. 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.
However, while the technique represents a huge step forward for gene therapy, it has also courted controversy, with fears being raised over its ethical implications and the risks of generating unknown side-effects. This debate reached a crescendo earlier this year when Chinese scientists used CRISPR to genetically modify human embryos. Having pre-empted the concerns this would trigger, the scientists deliberately used embryos that were not capable of giving life, yet 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.