Behind the Paper - Biological sampling: Pipetting in microgravity

Discover the story behind our paper, "Evaluation of techniques for performing cellular isolation and preservation during microgravity conditions", which was published in npj Microgravity

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Our article entitled "Evaluation of techniques for performing cellular isolation and preservation during microgravity conditions" was published in the journal npj Microgravity. The Nature Research team had a few questions for us about our article, which we have answered below.

Authors: Brian E. Crucian and Andrew P. Feinberg

Additional Co-Investigators: Lindsay F. Rizzardi, Hawley Kunz, Kathleen Rubins, Alexander Chouker, Heather Quiriarte, Clarence Sams

What was the main aim of your research and why did you decide to investigate this?

This article represents joint publication of a collaborative effort between the Johns Hopkins University School of Medicine and the NASA Johnson Space Center. The purpose of this study was to enhance bio sample collection capability on board the international space station. Currently bio sampling and processing during space flight is primarily limited to collection and freezing of urine and/or blood plasma. As terrestrial analytical capabilities expand, including various advances in the areas of molecular biology and ‘omics’ analyses, it is desirable to expand bio sample capability during flight to enable such research on board the International Space Station (ISS). These techniques generally require cells, purified cells, or some basic processing such as the addition of preservatives to isolated cells. The ground processing for such samples, relying on (perceived) gravity dependent techniques such as pipetting, overlaying of liquids, etc. were generally thought incompatible with microgravity conditions. The current effort sought to validate techniques to perform these basic processing steps in microgravity. In some cases the effort used typical ground equipment (pipettes, etc.) with no real modification, or used more unique hardware such as CPT blood tubes or newer septum-containing vessels for density gradient centrifugation.

How did you go about designing your study?

Dr. Feinberg was a PI for the ‘Twins’ investigation which took place on the recent 1-year mission on board ISS. Dr. Crucian is PI for the current ‘Functional Immune’ flight investigation on board ISS. Both laboratories considered what was required to translate terrestrial processing techniques to microgravity. While the Johns Hopkins effort focused on protocols using the CPT mononuclear isolation tube, the NASA group focused on traditional density gradient separation with septum tubes. Both laboratories validated the pipetting steps to enable blood processing, evaluating several different types of pipettors. The primary activity was an evaluation of all techniques thought to be potentially compatible with weightlessness, on board the NASA parabolic flight aircraft. This laboratory aircraft generates approximately 30 seconds of microgravity per parabola, and up to 40 parabolas are flown per mission.

What challenges did you face?

The primary challenges were those associated with performing an experiment on board this very unique aircraft. Safety is paramount. All equipment the equipment, reagents and protocols were vetted by review boards prior to flight. Also, simply executing the study in microgravity is challenging. One must be affixed to the workspace, and complete tasks quickly (using now-weightless arms, itself a challenge). We were not sure, until the initial trials were attempted, if fluids would be manageable at all during microgravity, especially in the larger vessels. Also, all of the individual steps required protocol validation needed to be performed in separate 30-second windows of time. This study was executed over four separate flights, employing several human ‘evaluators’.

What were the key findings from your research?

The key findings are, as described in the article, that terrestrial sample processing techniques are indeed possible in a microgravity environment. This includes the opening of vessels containing liquids, and the pipetting of those liquids using standard laboratory pipettes. The videos attached to the article, viewable on the internet, demonstrate these findings most effectively. Also, relatively sensitive steps such as fluid overlay and extraction also seem possible.

What next? What further research is needed in this area?

There are operational constraints and safety requirements on board ISS which are significantly more stringent than those found in any terrestrial laboratory. Therefore, we will likely not see a rapid deployment of these techniques to ISS. However, we have now demonstrated that such sample processing is indeed possible. Bio sample processing on board ISS could be expanded beyond simple freezing of urine or plasma. Therefore, any new flight experiment could reference this article and request pipetting steps in-flight as part of their experiment, to be considered for approval by NASA and the various other boards that review the technical requests of newly-selected flight investigations.

Read the article in full

Brian Crucian

Scientist, NASA Johnson Space Center