Polymerase chain reaction (PCR) that is out of this world

The Takeaway: Polymerase chain reaction (PCR) is a lab technique that can make millions and even billions of copies of a specific DNA sample. Lab equipment needed for PCR includes reagents, mixes, enzymes, thermal cyclers, refrigeration equipment, pipettes, and more. Sounds good—except, what if that lab is 254 miles above the surface of the Earth?

Polymerase chain reaction, or PCR, is a well-established, widely used lab technique that rapidly makes millions and even billions of copies of a specific DNA sample. This amplification allows the DNA to be studied with incredible detail. Its simplicity and power have made it useful for doing everything from analyzing tumors to detecting pathogens to identifying criminals. PCR labs are relatively simple to set up, and can be affordable, with options for leasing or even renting thermocyclers. But while PCR labs can be found all around the world, there’s one in particular that stands out—the PCR lab in the International Space Station.

What is polymerase chain reaction (PCR)?

PCR is a lab process to rapidly produce—or “amplify”—millions or billions of copies of a specific segment of DNA for the purposes of detailed study. An enhanced method of PCR called quantitative PCR (qPCR, also known as real-time PCR) measures the amplification of DNA in real time as opposed to at the end of the cycle. PCR and qPCR have led to advancements in gene expression, cloning, and genotyping. In addition to thermal cyclers, refrigeration systems, and other pieces of hardware, PCR relies on high-quality primers or probes. IDT provides probes and primers made using a proprietary platform that improves coupling efficiency during synthesis, with subsequent purification steps producing high-quality primes and probes.

PCR in outer space

Polymerase chain reaction was first conducted in space in 2016. Crew members used reactions designed by a high school student from New York and ran them on a miniature thermocycler that can be controlled by a phone. The effort was borne from the Genes in Space program, an annual contest that lets middle and high school students design DNA experiments that address challenges in space exploration. Since 2016, multiple experiments have taken place aboard the International Space Station to amplify DNA for research and educational purposes.

PCR helps protect the space mission

PCR is used in space for more than just experiments—it’s also the heart of a microbial monitoring initiative. Each time new crew come aboard the space station, or new supplies are delivered, there is the chance to introduce microorganisms and potential human pathogens. These pathogens and microbes could wreak havoc both on the astronauts and their equipment—and even life support equipment. A NASA report from 2017 described the process to choose and install a PCR system on the International Space Station.

Nucleic acid detection on the ISS using LAMP

In a 2020 study, researchers described a simple DNA diagnostic test used aboard the International Space Station that used loop-mediated isothermal amplification, or LAMP, that permitted the detection of a repetitive telomeric DNA sequence in about a half-hour. The test used instruments already on the space station and the results were available immediately. Astronauts used IDT primers exclusively in their research.

“Our results indicate that telomeric repeats may be amplified in space without adaptations to the hardware or reaction conditions,” researchers wrote. “This opens the door for the development of tools and diagnostic platforms that can be used broadly to detect targeted DNA sequences.”

What is next for PCR?

So polymerase chain technology has been to space and back—what is next? With next generation sequencing playing increasingly important roles in medical research, PCR is set to see expanding roles. Developing technologies such as microfluidics will perform RT-PCR for analysis, and droplet-based qPCR for gene expression and mRNA purification, will ensure PCR’s important future roles. Field crime scene analysis will also use PCR for DNA profiling on a chip, and the miniaturization of PCR will continue to develop sample-to-answer systems for point-of-care applications.