Can genetic engineering help humans live in space? [SA3] As billionaires are pursuing their interest in space exploration, the prospect of a mission to Mars is becoming more credible. CEO of Tesla and SpaceX, Elon Musk, a vocal proponent and investor in this endeavor, says the deadline for a Mars mission may be as early as 2024 . With a plan to send an unmanned vehicle there in two years, Musk hopes to help humanity become a multi-planet species . This possibility raises questions about how to survive the trip and, in the future, inhabit an atmosphere hostile to humans. Geneticist Christopher Mason, author of The Next 500 Years: Engineering Life to Reach New Worlds, highlights the applications of genetic engineering in this field . While there are arguably more biologically and ecologically significant uses of this technology, with the amount of funding being allotted for space travel, it is necessary to consider the impact on human bodies and the work’s additional implications for the general population.
The first step in this project is researching how certain genes are expressed during different stages of spaceflight, specifically during the intense return to Earth. Beginning with animal models, sending mice to space and analyzing the changes in DNA structure has shown retinal performance may decrease over extended spaceflight and cause visual impairment . Specifically, there were changes in chromatin structure of photoreceptors and an increase in retinal stress, leading to changes in the observed phenotype . This has been observed in humans as Astronaut Ophthalmic Syndrome (AOS), a condition some astronauts experience ocular changes in the lens and shape of the eye. This has further health indications on Earth, as the same genetic variants and serum factor changes that are associated with AOS are found in Polycystic Ovary Syndrome (PCOS), a condition that leads to infertility in women. There is also evidence of genetic changes to biological pathways of bone formation and the immune system .
Moving to human models, Mason led one of the teams of researchers NASA chose to study twin astronauts Mark and Scott Kelly. Scott Kelly spent a year on the International Space Station while Mark Kelly stayed back on Earth, providing a control to observe biological reactions. The genetic changes were categorized into low, medium and high risk. Low risk changes, which comprised about 93% of all changes, reset to normal when Scott returned to Earth; however, medium to high risk changes didn’t reverse after six months and are being monitored by their team. With more information about how long-duration missions affect human bodies, priorities for future space travel can be informed .
One of the main health concerns with space travel is radiation exposure and there is speculation that deep-space radiation is worse than expected, exceeding trends from previous solar cycles by at least 30 percent . If scientists can alter human cells to be more resilient to radiation effects, there could be fewer negative side effects, such as gene alteration, cancer or cardiovascular disease, from longer durations in space. A solution lies in the DNA of tardigrades, or water bears: microscopic aquatic invertebrates that can withstand extreme environments, including the vacuum of space. They possess a protective protein, named Dsup, that provides resistance to radiation, which scientists have been able to transfer to human cells. Dsup prevents tardigrade’s DNA from breaking down under this radiation stress, suppressing about 40% of the damage . This trait is an adaptation to severe dehydration, which can tear DNA apart similar to radiation . In theory, this technology could also be applied to combat the effects of radiation on healthy cells during cancer treatments .
When considering how to apply this technology, it is important to involve epigenetics, which is the study of processes that alter gene activity without changing the actual DNA and lead to modifications that can be passed to offspring. Current data shows that there are variations in gene expression after space travel, but it is still unclear why this occurs. Epigenetics can help identify cell pathways that can adapt and survive in the microgravity environment, such as the bone loss that astronauts experience on extended missions.
The challenge here is most traditional DNA sequencers don’t have the kind of precision required to analyze specific gene changes in space. The space station has a tool called MinION™, which is a DNA sequencer tailored to the microgravity environment. It sends a positive current through pores embedded in the device’s internal membrane, called nanopores, while fluid with DNA passes through simultaneously. Individual DNA molecules partially block the activity of these nanopores and change the current in a way specific to the particular DNA sequence. On Earth, air bubbles that form in the solution can rise to the top and be removed by a centrifuge, a device that spins fluids at high speeds to separate different densities or states of matter. In space, however, these air bubbles will not rise and have the potential to block the nanopore’s behavior . Astronauts can culture organisms onboard their spacecraft and this device can see changes in methylation patterns, a marker of epigenetic regulation, without having to fix or freeze the sample, which can alter the readings. The goal is to replicate a terrestrial laboratory environment with high-tech equipment and processes in this compact device without having to wait for gene samples to return to Earth for testing. This DNA sequencer is also being tested on Earth with applications in low-resource environments, such as for medical operations in regions without access to a full laboratory .
There is a promising future for applications of gene editing technology, whether in the form of colonizing Mars or a variety of other healthcare advancements, there is a promising future for applications of gene editing technology. Mason comments on the inevitability of this idea, stating, “genetically editing humans for space travel would likely be a part of natural changes to the human physiology that could occur after living on Mars for a number of years. It’s not if we evolve; it’s when we evolve” .
Edited by: Arjun Singh
Illustrated by: Shanthi Deivanayagam