Imagine a world where organisms, off of the desire of any mind, are simply created. Envision a world in which diseases and disorders are absent. These thoughts, that were once dreams, now become possibilities due to the emergence of a newfound technology: CRISPR Cas9. “The field of biology is now experiencing a transformative phase with the advent of facile genome engineering in animals and plans using RNA-programmable CRISPR Cas-9,” (Doudna and Charpentier, 2014, p. 1077). As part of an archaic bacterium defense system, CRISPR “relies on a protein called Cas9'' to make target specific strand breaks in the DNA’s double helix (Pennisi, 2013, p. 334). Furthermore, “...methods for introducing precise breaks in the DNA at sites where changes are to be introduced was recognized as a valuable strategy for targeted genomic engineering,” (Doudna and Charpentier, 2014, p. 1). Deemed as a simple and efficient method, CRISPRs art of reconstruction creates all around opportunities for its user. However, the quick advent of the CRISPR technology seems too good to be true. As a versatile and effective method for various fields of science, CRISPRs concerns are greatly overlooked. Aside from mere ethical concerns, there are issues that go beyond editing the human germline. As a relatively new piece of technology, and one that could potentially alter the different approaches in science, CRISPRs possibilities and limitations must be examined deeply.
To fully comprehend the pros and cons of CRISPRs uses, its functionality must first be understood. CRISPR, short for clustered regularly interspaced palindromic repeats, is a defense mechanism present in almost all bacterial genomes. Some bacteria immune systems are structured “...where foreign DNA is incorporated between palindromic sequences to provide the bacteria with a molecular ‘memory’ of viruses that have previously invaded the bacteria,” (Webber, 2014, p. 331). Furthermore, Webber (2014) states that if the same virus infiltrates the bacteria the next time around, the bacteria will use its CRISPR sequences to recognize it, in which the virus is then destroyed by its Cas enzymes (p. 331). Genome editing mechanics similar to these have been around for quite some time now, but location specificity was a recurring problem. CRISPR Cas-9’s partnership has only become useful to myriad scientists and researchers because “...It takes aim at specific DNA sequences,” (Pennisi, 2013, p. 833). The preciseness of this function is extremely beneficial because scientists are able to cut out an exact section of DNA, and replace it with sections that they have engineered themselves, or even sections that will prove useful for the organism itself (Crauciuc et al, 2017, p. 4). In regards to CRISPRs facile and effective functionality, it sounds almost too good to be true. A new type of technology that is able to perform unrealistic tasks at ease, is suddenly introduced without any implementations. However, its history proves otherwise.
An insight to CRISPRs potential first appeared as a result of an attempted experiment to strengthen the defenses against bacteriophages of dairy microbes. This was essential for dairy industries because they depended on bacteria such as “...Streptococcus thermophilus to make yogurts and cheeses,” (Pennisi, 2013, p. 833). However, if a bacteria such as this is infected by certain viruses, it will have a huge effect on the quality of its production. According to Pennisi (2013), scientists exposed the bacteria to its invader, which eventually progressed into a defense system against the virus (p. 833). As a result, the production of food quality from this tactic increased. With that, the “...infection experiments of the lactic acid bacterium Streptococcus thermophilus with lytic phages provided the first experimental evidence of CRISPR Cas- mediated adaptive immunity,” (Doudna and Charpentier, 2014, p.1). In addition to this self-defense mechanism, and its location specific targeting, CRISPRs experimentation has reached out to a plethora of researchers. Pennisi (2013) states that within the course of months, multiple research groups have harnessed the power of its functionality to edit targeted genes in organisms such as human cells, mice, rats, yeast, crops, and more (p. 833). This versatility is one of the reasons which makes CRISPR all the more valuable.
An important factor in what makes CRISPR so advantageous, is its ability to open up numerous possibilities in terms of what science can do for humanity. As Doudna and Charpentier (2014) states, “...it could be harnessed for applications in molecular biology and genetics that were not previously envisioned,” (p. 7). Just to name a few, CRISPR can potentially advance the fields of gene therapy, pathophysiology, pharmacology, and even agriculture. For example, this procedure is already making its advantageous mark in that of genetic disorders. According to Crauciuc et al (2017), “Huntington’s is an autosomal dominant neurodegenerative disease caused by trinucleotide repetition (CAG) in the HTT gene after 40 CAG repeats, the majority of patients develop the signs and symptoms of the disease,” (p. 5). CRISPR, however, could reverse this outcome by excluding this repetition from the DNA sequence. In addition, CRISPR could be collaborated with other methods of therapy, such as stem cells, to possibly improve the editing process (Crauciuc et al, 2014, p. 5). This system does not only have patient implications, but can also progress research studies as well. Unknown human diseases may become known, and the genetic sequencing of those diseases may become known as well, due to CRISPR:
“Its application in genome-wide studies will enable large scale screening for drug targets and other phenotypes and will facilitate the generation of engineered animal models that will benefit pharmacological studies and the understanding of human diseases,” (Doudna and Charpentier, 2014, p. 1077)
As mentioned before, CRISPR enables the study of “...genomic rearrangements and the progression of cancers or other diseases, and potentially corrects genetic mutations responsible for inherited disorders,” (Doudna and Charpentier, 2014, p. 1077). In addition to being efficacious in terms of its implementations, CRISPR is cost effective.
“They are kind of crazy hot,” says Joanne Kamens, Addgene’s executive director,” (Pennisi, 2013, p. 836). CRISPR has not only gained much traction for its impressive qualities, but the mere fact that it is cheap and easily accessible, makes the technology all the more attractive:
“The cost of admission is low: Free software exists to design guide RNA to target any desired gene, and a repository called Addgene, based in Cambridge, offers the academics the DNA to make their own CRISPR system for $65,” (Pennisi, 2013, p. 836).
The “...cost-effective and easy-to-use technology…” (Doudna and Charpentier, 2014, p. 1077) is enabling the genetic field to move quickly and comfortably. Addgene, and eleven other research teams, distributed five-thousand CRISPR constructs, in addition to one-hundred constructs being sold in a lone week (Pennisi, 2013, p. 86). In all, it is evident that CRISPR has its clear advantages. All of the attributes that give it the bright future it has, make it impossible to resist. However, Caplan et al (2015) states that “Ensuring that CRISPR/Cas does not become touted as a panacea for all genetic illness is crucial for proper application and dissemination of the technology,” (p. 1425.) Although its potential seems plausible, with it, comes doubt.
The reason CRISPR should not be shown off as a life saving technique, is because of the several limitations that appear. Even if those limitations are cleared, there are questions that remain about its overall safety. Based on past and current studies, it seems as if for right now, CRISPR can only go so far as to be used for research purposes only. In addition, CRISPRs advantages, possibilities, and potential, are all theoretical. Contrary to the belief that CRISPRs precision is undeniable, one of the main safety concerns about it, stems from the fact that its current accuracy could create off-target effects:
“One of the most significant limitations of the CRISPR Cas9 system was the appearance of certain off-target effects, although these represented a small percentage compared to previous techniques of genetic engineering,” (Crauciuc et al, 2014, p. 7).
Off-target effects only mean that “...the CRISPR-Cas9 system interfered with other regions,” which in turn, caused a large number of mutations (Crauciuc et al, 2014, p. 7). For CRISPR to be used clinically and therapeutically, it is imperative that its safety is secured. In fact, “In March 2015, the researchers who worked to develop CRISPR acknowledged the unsafeness of this method…” (Crauciuc et al, 2014, p. 7). Human genome implications, even, have proved to be unsafe according to a group of Chinese scientists' experiments. Modifying the gene that causes sickle cell anemia on non viable embryos, they have found that only seventy-one of the eighty-six embryos survived, and of the ones that did survive, not all had the modified genetic information (Crauciuc et al, 2014, p. 8). According to the scientists, they declared “...that the technology was imperfect, and in order to be used on viable embryos, it should have a 100% success rate,” (Crauciuc et al, 2014, p. 8). These perspicuous evidence shows that CRISR undoubtedly has its own impediments. If the end goal is to truly use CRISPR to its maximum power, then risks will have to be minimized.
Aside from safety concerns, there are many other questions about this contemporary and powerful tool. One of CRISPRs potential utilities involves the use of it on animals. These applications include improving food for human consumption, increasing the muscle mass of certain animals, making some animals less prone to disease, or even making hornless cattle for easy handling (Caplan et al, 2015, p. 1422). However, the use of GMOs are still at debate, and CRISPR may be no exception to accepting genetically modified organisms. “...there is a danger that CRISPRs affordability could run roughshod over long-standing and valid concerns about the generation and release of… GMOs,” (Caplan et al, 2015, p. 1421). In addition, the use of CRISPR on animals does not only question the safeness of human consumption, but other factors as well:
“Can off-targets effects of CRISPR─unanticipated mutations leading to undesirable phenotypes─be controlled? What are the effects on animals who eat genetically edited insects or animals? Will wiping out an entire species─albeit invasive, or disease-bearing, such as mosquitos or ticks─ upset the ecological balance? Will edited organisms be able to survive in natural environments, and if so, for how long? (Caplan et al, 2015, p. 1423).
Moreover, CRISPRs potential of having an endless amount of possibilities, may call for needed restrictions and legislation. Other than all the positive things that CRISPR can do for society, it can also do as much bad for it as well. “...CRISPR could be co-opted for nefarious purposes, such as bioterrorism or biowarfare. The ease and efficiency of CRISPR raises the concern that anyone with the appropriate equipment could engineer a vaccine resistant flu virus or invasive species in a crude laboratory,” (Caplan et al, 2015, p. 1426). As mentioned before, despite CRISPRs great benefits and potential, in order to diminish its risks, proper guidelines will have to be established regarding its use.
It is evident that CRISPRs functionality provides its future with a rich profusion of potential in a plethora of scientific fields. Diseases may become yesterday’s history, and humanity may be altered due to a new era of genetic technology. However, even then, CRISPR has its own limitations. If these obstacles could be breached, then the only hindrance would be “...people’s ability to think of creative ways to harness CRISPR,” (Pennisi, 2013, p. 836). The field of genetics is moving quickly, and with researchers and scientists eager to explore the multiple new ways of harnessing CRISPR, this novel system could be fine-tuned to be the revolutionary item it was meant to be. Coming from an ancient system of bacterium defense, the advent of CRISPRs advanced performance seems to hold many perspectives in store.
References
Caplan, Arthur L., et al. "No time to waste—the ethical challenges created by CRISPR." EMBO
reports 16.11 (2015): 1421-1426.
Crauciuc, Andrei, et al. “Development, Applications, Benefits, Challenges and Limitations of the
New Genome Engineering Technique. An Update Study.” Acta Medica Marisiensis, vol. 63, no. 1, Mar. 2017, pp. 4–9. EBSCOhost, doi:10.1515/amma-2017-0007.
Doudna, Jennifer A., and Emmanuelle Charpentier. "The new frontier of genome engineering
with CRISPR-Cas9." Science 346.6213 (2014): 1258096.
Pennisi, Elizabeth. "The CRISPR craze." (2013): 833-836.
Webber, Philip. "Does CRISPR-Cas open new possibilities for patents or present a moral
maze?." Nature biotechnology 32.4 (2014): 331.
