NASA has announced that it used freeze-dried mouse sperm that spent months aboard the ISS to fertilize mouse overy eggs back on earth. The result of the experiment are a group of baby mice NASA has dubbed “space pups.” Japanese researchers are behind the experiment, with the results published this week in a new paper.
The goal of the experiment was to determine how space radiation impacted fertility in mammals. Scientists know radiation can damage DNA within cells, causing mutations, which is why dermatologists recommend humans on earth wear sunscreen. On Earth, environments with heavy radiation exposure can cause defects in the offspring of animals.
Space radiation continues to be a significant concern for spacefaring nations as astronauts spend more time and space, particularly in low Earth orbit. NASA and other space agencies also plan missions further into space in the future, such as putting humans on Mars for the first time. Before NASA sends astronauts on long-duration missions, it needs to know how the increased radiation exposure will impact the health of astronauts.
For this experiment, researchers freeze-dried mouse sperm samples from 12 different mice placed them inside lightweight capsules. The packets were transported to the ISS and stored for different amounts of time. Some of the samples were returned to earth after nine months in space, while another set was returned after two years and nine months. The final set of sperm samples came back after five years and 10 months in space.
When the samples were returned to earth, the team determine how much radiation they absorbed using RNA sequencing. The team found that the trip in space did not damage the sperm nuclei. Scientists rehydrated the sperm with water and injected them into fresh mouse ovary cells. After transforming the ovary cells into female mice, the mothers became pregnant and eventually gave birth to baby mice. The resulting space pups were healthy and had no defects.