CRISPR 101: Research Developments in 2017
By Kevin Holden, PhD, Head of Synthetic Biology at Synthego
This is the third part in the CRISPR 101 series by Synthego, providing a crash course on CRISPR-Cas9 and its applications in a wide range of life science disciplines.
CRISPR has rapidly morphed from a promising technology to an indispensable tool in genome engineering in just a few years. Its popularity is substantiated by a 20-fold increase in the number of CRISPR-based publications from its introduction in 2012 to date. With a large number of researchers embracing this method, CRISPR has ushered in ideas for sophisticated applications relying on fine-tuning the genome with superior control. This has necessitated development of advanced molecular biology tools to meet the dynamic challenges of the technology.
Synthego has been proactive in identifying challenges with CRISPR genome editing, and providing cost-effective solutions for researchers. For instance, a recent Synthego survey of the CRISPR research community showed that 67 percent of CRISPR users predict it will have a large impact in stem cell research, but that the existing technologies fell short of yielding the desired editing efficiency. To solve this issue, Synthego introduced chemically modified synthetic sgRNA this year, which enables highly efficient CRISPR gene editing and knockouts – up to 90 percent – in stem cells. Available for the first time ever at a practical cost and turnaround time, CRISPR tools such as these will allow more researchers to quickly adopt the technique in the near future, further accelerating research in this field.
In this installment of CRISPR 101, we’ll take a look at some of the cutting-edge genome engineering research that CRISPR is helping to advance, with a focus on human therapeutic applications.
What were some of the important CRISPR-based research studies in 2017?
The advancements in CRISPR technology led to several significant research milestones this year. We can’t possible cover them all, but here are a few notable studies:
1. Mice rescued from retinitis pigmentosa-induced blindness
Precise gene editing using CRISPR is a boon for testing therapeutic options for genetic diseases — a prime example being retinitis pigmentosa. In this genetic disorder, rod-cells in the eyes responsible for peripheral and night vision start degenerating. Death of the rod-cells triggers degeneration of the cone-cells, which are responsible for daytime and color vision, resulting in complete blindness over time. In two independent studies1, 2 this year, researchers used CRISPR to knockdown the Nrl gene, which is responsible for rod function. This modification effectively reprogrammed rod-cells into cone-cells, and rescued mice from permanent blindness.
2. Increased possibility of organ transplants from pigs to humans
In the US, approximately 75,000 people are on the waiting list for obtaining human organs for transplantation, and about 22 people who are in dire need of an organ transplant die per day. Given these statistics, xenotransplantation (transplanting organs from animals in humans) could offer a viable solution.
The idea of transplanting organs from pigs to humans has been around for a while, but one major concern has been the porcine endogenous retroviruses (PERV) sequences in the pig-genome. These genes are remnants from viruses that infected pigs millions of years ago. Concern that these retrograde virus genome fragments could infect humans has been a major roadblock delaying the testing of organ transplantation from pigs.
In August 2017, researchers used CRISPR to slice out all 25 PERV sequences from the pig genome3. They were able to produce healthy piglets free of PERV sequences in the lab. Although the issues of how the human body might react to porcine organs remains to be seen, this huge breakthrough brings us one step closer to harnessing animal organs for human transplants in the future.
3. Gene editing in human embryos
The most significant, and perhaps the most controversial, study this year was the application of CRISPR in the human embryo. Scientists corrected a mutated gene (MYBPC3), which is responsible for thickening of heart muscles, during in vitro fertilization4. This modified method of introducing the CRISPR components at the same time as sperm-injection, rather than after fertilization, drastically reduced the number of mosaics (different cells containing different genetic sequences) in the embryo.
However, aside from the ethical debate of editing human embryos the study fell under severe scrutiny from the CRISPR community. Peers challenged the author’s interpretation of that a DNA template from the egg was involved in gene repair after CRISPR editing5, claiming that the sperm and egg are too far away for any DNA interaction during fertilization.
Despite the controversial details regarding safety of this method, it remains an exciting first attempt by a US team to use CRISPR in human embryos, a technology that could prove very useful in resolving diseases caused by germline mutations.
What can we expect from CRISPR in 2018?
CRISPR-based research achievements in 2017 have laid the foundation for even bigger expectations from the upcoming year, with several gene therapy applications likely to emerge. Here’s just a few of the research highlights we might expect to see from the CRISPR research community in the coming year:
Model organisms for studying diseases play a key role in developing therapeutic options – In the past, the development of transgenic and knockout ice has been costly and time consuming. Modern CRISPR tools have greatly simplified this process, allowing researchers to also modify more complex animals like pigs and human embryos.
Manipulation of our own immune system’s T-cells – By inserting chimeric antigen receptors (CAR genes) which produces receptors that recognize tumor cells, is a promising way to fight cancer. Known as Car-T therapy, researchers in 2017 showed that using CRISPR allows CAR gene insertion at a precise location in the chromosome, which makes the CAR-T cells more potent6. Therefore, improved therapy options and clinical trials for fighting cancer using this method are likely to surface in the near future.
It would not be a stretch to say that CRISPR research in both academia and industry will progress in leaps and bounds in 2018, with new discoveries and applications sure to come.
Synthego is a leading provider of genome engineering solutions. The company’s product portfolio includes software and synthetic RNA kits designed for CRISPR genome editing and research. With next-generation informatics and machine learning, Synthego’s vision is to bring precision and automation to genome engineering, enabling rapid and cost-effective research with consistent results for every scientist.
Headquartered in Silicon Valley, California, Synthego customers include leading institutions in over 32 countries around the world, 8 of the world’s 10 largest biotechnology companies, and 24 of the top 25 global biology universities.