March 30, 2018
By Greg Peters
|Joe Tash in his lab at KU Medical Center.|
If mankind is to venture into deep space one day, the road to such an ambitious mission might just begin right here at the University of Kansas Medical Center in the laboratory of Joseph S. Tash, Ph.D., emeritus professor in the Department of Molecular and Integrative Physiology in the School of Medicine.
Tash is researching the effects microgravity has on human reproduction, specifically what extended time spent in outer space will do to the functionality of sperm. To that end, Tash will soon be sending frozen samples of human and bull sperm aboard SpaceX's Falcon 9 rocket to the International Space Station in hopes of finding out if humans will be able to reproduce in space, which could prove to be vital.
"One of the long-term interests of NASA is looking at multi-generational survival as we plan longer and longer-duration missions," Tash said. "As we plan to travel beyond the space station with thoughts of colonization on the moon and Mars and other heavenly bodies, the question of whether or not multi-generational survival can occur - not only in animals but in humans - is a very fundamental question that needs to be addressed."
A key to extended space travel or colonization of other planets, whether it's to Mars, the moon or beyond, will be the necessity for humans to procreate in space. Little is known about how microgravity affects the biology of human reproduction and most important, how these conditions might affect the functionality of sperm. While other reproduction research has been conducted before this, Micro-11 (SPERM-03) will be the first to test the functioning of human sperm in space.
Liftoff of Commercial Resupply Service 14 mission (CRS-14) with the Micro-11 mission onboard is set for 3:30 p.m. (CST), April 2, from Cape Canaveral Air Force Station in Florida. Watch the rocket launch live: https://www.nasa.gov/nasalive.
Motility and capacitation
In humans, as well as other mammals, fertilization happens when a sperm cell fuses with an egg. Before that can happen, sperm must travel to the oocyte (a cell in an ovary that may undergo meiotic division to form an ovum), which requires the sperm to start moving. This is known as motility activation. On board the space station, astronauts will thaw the sperm samples and combine them with a chemical mixture to trigger motility activation.
In order for a sperm cell to fuse with the egg, it must then start moving faster and its membrane must become more fluid; certain proteins are modified and changes occur in the sperm head allowing it to fuse with the egg. These steps together are known as capacitation. Half of the samples will then be activated by a chemical mixture that promotes capacitation, while a control group will be combined with a chemical mixture that does not trigger capacitation.
This isn't Tash's first time sending sperm beyond the tug of Earth's gravity. In 1997, he sent two experiments involving sea urchin sperm on space shuttle missions just six months apart. Those experiments (SPERM-A and SPERM-B) proved invaluable both in terms of knowledge gained and scholarly publication. The findings suggested that in microgravity, motility activation happens much faster, while conversely capacitation happens more slowly or not at all. As a result of delays or problems with sperm capacitation, fertilization in space may not be possible.
Now, some 21 years later, frozen samples of human and bovine sperm are about to be sent to the ISS with identical samples being used on the ground in tests that mimic those going on into space.
Special equipment, developed by BioServe, NASA's flight integration partner, was created for Micro-11 in order for the astronauts to conduct the experiments in space. This included a special microscope camera system and imaging cassettes to contain the solutions, while still allowing researchers to observe motility for up to an hour.
An identical camera and microscope are in Tash's lab at KU Medical Center and in a lab set up for Tash at Kennedy Space Center's Space Station Processing Facility (SSPF) in Florida. Tash and his team produced training videos to aid the astronauts while they were being prepared for the mission by BioServe's flight integration team. Videos taken through the microscope in space will be recorded and sent to Earth, so researchers can assess how well the sperm swim.
"The logistics to prepare for this type of experiment are quite detailed," Tash said. "As one might imagine, doing a simple in vitro experiment for sperm, in a laboratory on the ground you don't have to worry about your test tubes and pipette tips and gloves floating off into the room."
The human samples were supplied by California Cryobank Inc., while the bull semen came from Kansas State University's Kansas Artificial Breeding Service Unit. Pool semen samples from 12 humans and six bulls were created to be tested in triplicate during asynchronous testing in space and on the ground at Kennedy Space Center.
After motility experiments are completed, the sperm will be preserved so that they can be analyzed and compared to the cells used in the parallel experiments on Earth. The microscope video recordings and test samples will return to Earth aboard the Dragon capsule on May 3, and then sent to Tash's lab at KU Medical Center for further study.
"What we hope to find is whether space flight has an effect on sperm motility," Tash said. "And if there is a difference, where does that difference occur? Are there changes in sperm membranes? Changes in phosphorylation of key proteins?"
Tash is quick to point out that none of this work could be possible without the amazing and tireless efforts Eric Yarns, the primary research assistant for the project in his lab, Luan Ngo and other student volunteers. He also credits BioServe's Luis Zea and the company's excellent flight integration team, plus NASA for its funding and its overall project support team."
But it's not all work and no play when it comes to Tash's sperm research. An old acquaintance of Tash's, one who may be familiar to many people outside the science realm, has thrown his talents into the mix. Matt Groening, the creator of "The Simpsons," developed the Micro-11 experiment patch complete with astronaut Homer Simpson riding an angry-eyed, bull-headed sperm cell through outer space, complete with his tail a-wagging.
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Gustavo Blanco, M.D., Ph.D., will serve as the principal investigator for the grant as Tash phases into emeritus status.