Contrary to public opinion, space is not an empty place.
Near Earth, unconscionable levels of ionizing radiation swarm around our tenuous atmosphere, protected only by our magnetosphere. It comes largely from galactic cosmic radiation, fueled by the seemingly endless activity of the Milky Way. With this maddening reality in mind, a group of scientists investigated the possibility of using CRISPR gene editing systems in space, to safely and accurately test the effects of ionizing radiation on human-like cells aboard the International Space Station, according to a new study published in the journal PLOS ONE.
In other words, we just took the first step to circumvent a major impediment to the human exploration of deep space: Radiation exposure, which can cause cancer, and other life-threatening complications.
Developing a CRISPR 'toolkit' for deep-space experiments
As humans push further and farther into deep space, astronauts could risk harmful levels of exposure to ionizing radiation, which can damage DNA. One type of DNA damage, called double-strand breaks, may be repaired via two cellular pathways. One is called homologous recombination, which involves cases where the DNA sequence is typically left unchanged. The other, called non-homologous end joining, sees insertions or deletions added to the break site. Earlier work on double-strand breakages has led to suspicions that conditions in space could affect which DNA repair pathway, which could compound the risks of increased exposure while traveling in space.
However, scientists haven't had bountiful opportunities to grasp this problem, mainly because of safety and technical issues. But the CRISPR/Cas9 gene-editing system can provide a model to safely and accurately generate double-strand breaks in eukaryotes, the kind of cells humans use. The study's findings are the first-ever expansion of scientists' molecular biology "toolkit" aboard the International Space Station.
Beyond the protective shield of the Earth's magnetosphere, ionizing radiation places any present astronauts at risk of extensive DNA damage. This can lead to cancer and other serious health risks, throwing the entire notion of deep space travel into question. Double-strand breaks (DSBs) are when the phosphate backbones of both DNA strands are compromised and form into a DNA lesion. In the depths of space, much of the ionizing radiation is galactic cosmic radiation, consisting mainly of high linear energy transfer (LET) particles. These can punch through DNA, causing clustered and complex DNA damage that is not easy to repair. This means knowing which of the two repair pathways mentioned above is optimal is crucial to mitigate damage in astronauts exposed to space radiation.
Scientists develop the first molecular biology workflow in space
Earlier studies have shown that the DNA repair mechanism pathway may be influenced in conditions under a measure of microgravity. But these studies have typically relied on generating DSBs on Earth, then freezing the biological material to be lifted to space, so scientists could observe which DNA repair pathway would happen in microgravity. But, since the two-road pathway is often determined immediately after a DSB event, it's possible these experiments futilely lifted eukaryotic cells that had already begun one pathway in Earth's full gravity, before astronauts could witness it in microgravity. This is why the scientists sought a means to study DSB breaks and repair entirely in the microgravity environment of the ISS.
Ultimately, the scientists successfully developed the first molecular biology workflow to examine DSB repair, from start to finish, aboard the ISS. And it happened with CRISPR/Cas9 gene-editing systems. Notably, in addition to kicking off a new series of DNA repair studies in microgravity, astronauts have gained the ability to transform and genetically engineer living organisms in space, which could serve to seed many further experiments in the future of human space travel.