Spaceflight-Altered Motility Activation and Fertility-Dependent Responses in Sperm (Micro-11) - 08.15.18

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Spaceflight-Altered Motility Activation and Fertility-Dependent Responses in Sperm (Micro-11) examines whether spaceflight alters human sperm by tracking the swimming patterns of human and bull sperm during spaceflight. This investigation also assesses other aspects known to be related to male fertility. As a result, Micro-11 provides fundamental data indicating whether successful human reproduction beyond Earth is possible, and whether countermeasures are needed to protect sperm function in space.
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Information Pending

The following content was provided by Joseph S. Tash, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: Micro-11

Principal Investigator(s)
Joseph S. Tash, Ph.D., University of Kansas Medical Center, Kansas City, KS, United States

Information Pending

BioServe Space Technologies, Boulder, CO, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
NASA Research Office - Space Life and Physical Sciences (NASA Research-SLPS)

Research Benefits
Information Pending

ISS Expedition Duration
February 2018 - August 2018

Expeditions Assigned

Previous Missions
STS-81 STS-84 STS-131 STS-133 STS-135 BION M1 (unmanned Russian Space Biology Mission)

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Experiment Description

Research Overview

  • The survival of multiple generations of organisms beyond the Earth requires proper function of normal sperm and eggs cells. There exists a significant knowledge gap on impacts of spaceflight conditions on the fertility-dependent functions of sperm. The goal of the Spaceflight-Altered Motility Activation and Fertility-Dependent Responses in Sperm (Micro-11) investigation is to study how sperm cells are affected by the spaceflight environment.
  • The hypotheses studied during Micro-11 include: a) whether sperm motility is activated more rapidly in microgravity than on Earth, and b) the response of sperm (motility hyperactivation, and morphological changes) to fertilization activating conditions, as well as the underlying metabolic and regulatory mechanisms, are delayed or blocked in microgravity.
  • Identical cryopreserved aliquots of human and bovine sperm are cryopreserved using established clinical and commercial procedures, and are stable (maintain fertility and function) for years under ultracold storage conditions. Data from Micro-11 provides the first rigorous test of how spaceflight affects the sperm functions required for male fertility.


The Spaceflight-Altered Motility Activation and Fertility-Dependent Responses in Sperm (Micro-11) investigation studies how sperm cells are affected by exposure to the spaceflight environment. Previous studies have shown that:
  • Sounding rocket experiments demonstrated that bull sperm swim faster during brief exposure to microgravity
  • Shuttle-Mir experiments found that sea urchin sperm show faster internal signaling during start of sperm tail movement, but response to egg fertilizations factors is delayed
  • The BION M1 mission (unmanned Russian space biology mission) showed that male mice, after 30 days of spaceflight, had disrupted testis spermatogenic organization and reduction of sex steroid hormone gene pathways
These flight data suggest that spaceflight has an impact on male fertility.
The specific aims of Micro-11 are to determine: 1) If the activation of human and bovine sperm motility in micro-G is more rapid and produces higher velocity parameters, as compared to normal Earth gravity (1G); and 2) If the human and bovine sperm motility, and acrosomal morphological changes produced by egg chemotactic/activating factors are blunted in microgravity versus 2G.
The potential fertility of sperm can be assessed in-vitro using standard clinical and cutting edge outcome measures, similar to what is used clinically for in vitro fertilization, and without the need for eggs. This flight project is the first to apply proven analytical methods to assess the fertility of human and bovine sperm in space flight. Sperm from humans and bulls are flown to the International Space Station (ISS) in an inactive state, prepared by cryopreservation from nationally established sources of human clinical and cattle industry semen.
Identical aliquots of sperm pooled from pre-selected donors from both species, respectively, eliminates donor-to-donor variation and provides enough aliquots to allow flight and ground experiments to be conducted on identical samples. Standard methods for activation of sperm for clinical and veterinary assessment and use in-vitro fertilization, respectively, have been adapted for use in spaceflight.
Sperm is activated in spaceflight under conditions known to trigger the ability of sperm to fertilize eggs (capacitation), but in the absence of eggs. Two different activation media are used: 1) Capavitation medium to trigger capacitation and canonical changes in motility, signal transduction, morphology, and metabolism, and 2) Non-capacitating medium (control medium) that activates motility, but inhibits the capacitation changes in motility, signal transduction, morphology, and metabolism required for sperm to be capable of fertilizing an egg. Parallel asynchronous Capacitating and Non-capacitating activated sperm ground controls are compared using identical aliquots of the pooled cryopreserved sperm used in flight.
Based on previous flight studies using sea urchin sperm and earlier German sounding rocket studies using bovine sperm, it is predicted that spaceflight increases sperm motility compared to on Earth, but delay or inhibit the panel of canonical biomarker changes associated with capacitation.
In flight, ISS crew members thaw the sperm samples and buffer media (syringes and FEP Teflon bags) in the Commercial Generic Bioprocessing Apparatus (CGBA) or the Space Automated Bioproduct Laboratory (SABL) (from BioServe Space Technologies) at 37°C and room temperature, respectively, then mix the sperm in capacitating and non-capacitating media inside the Microgravity Sciences Glovebox (MSG). An inverted microscope with special chambers to contain the sperm is used to record motility via an attached video camera. Video files are downlinked later for image analysis to quantify motility parameters. Separate aliquots of the activated sperm are fixed with paraformaldehyde (PFA),
Radioimmunoprecipitation assay (RIPA) buffer, and Methanol, and stored at -80°C and +4°C for subsequent analysis of metabolic, morphologic, and signal transduction changes by the research team after sample return. The aliquots of human and bull sperm each represent identical donor pools of sperm, respectively. This fact, combined with the exceptional stability of many months of the cryopreserved sperm, activation media, and fixatives provides ideal flexibility for incorporating the experiment into the crew schedule when time permits.

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Space Applications
Survival of multiple generations of organisms beyond Earth requires proper function of normal sperm and egg cells. The ability of sperm to swim and to fertilize an egg are fundamental components of male reproduction necessary for species survival on Earth and in space, but scientists do not fully understand how spaceflight conditions affect these functions. This investigation is the first comprehensive assessment of fertility characteristics of sperm, and their underlying mechanisms in microgravity. It also contributes to the NRC 2011 Decadal Survey to discover and characterize underlying mechanisms of adaptation to the spaceflight environment, and to determine cellular and organismal mechanisms that regulate and sustain reproduction and development in space.

Earth Applications
Many changes to the human body caused by spaceflight parallel those caused by the aging process on Earth. Reproductive health declines with age, as seen in reduced production of hormones and of sperm. Recent studies suggest that age-related declines in hormone signaling may play a role in other effects of spaceflight. Data may help identify novel approaches for addressing the more debilitating aspects of the aging process on Earth, thus improving quality of life.

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Operational Requirements and Protocols

Human and bovine sperm (6 samples of each type) are launched frozen, and once on orbit, are thawed using BioServe's Thawing Pouches and introduced into culture bags. A culture bag contains either capacitating or a control incubation medium. A sample from the bag is transferred into an imaging cassette to be placed under the microscope, where video is recorded at 6 different times during each 1-hour experiment. Samples are also collected from the bag at each of those 6 times and fixed for postflight analyses.
The experimental protocol is defined for the Biological Samples and Experimental Design:
  • Biological specimen
    • Bovine sperm
    • Human sperm
    • Bovine samples are from a single pooled source
    • Human samples are either from pooled donors, or from 3 distinct donors
    • Three replicates per species per condition
    • Two activation conditions (capacitation and non-capacitating)
    • Two gravity conditions (1G and micro-G)
    • Number of samples: either 12 (24) samples altogether (12 Flight and 12 Ground).
  • Hardware
    • Biological samples and buffer solutions in syringes
    • Ascent: POLAR <-80°C
    • Minus Eighty-Degree Freezer for ISS (MELFI) (-95°C)
    • Commercial Generic Bioprocessing Apparatus (CGBA) or Space Automated Bioproduct Laboratory (SABL) incubators at 37°C from BioServe Space Technologies
    • Microgravity Science Glovebox (MSG) and Video Upgrade Equipment (VUE) camera and recording hardware 
    • FEP Teflon bags for activation
    • BioServe microscope.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites

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NASA Image: ISS056E094996 - NASA astronauts Drew Feustel and Serena Auñón-Chancellor are seen while Auñón-Chancellor works inside the Microgravity Science Glovebox (MSG) on the Micro-11 investigation. The study looks to provide fundamental data indicating whether successful human reproduction beyond Earth is possible.

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