In Situ Space Protein Crystal Growth: A New Approach to Conducting PCG Research on ISS

摘要

There are several spaceflight-related limitations that can negatively impact the outcome of protein crystal growth (PCG) research on the International Space Station (ISS). First, most spaceflight hardware is uniquely designed and requires many months to perfect experiment protocols to produce reliable results in the hardware. Second, samples and solutions often must be kept physically separated or refrigerated/frozen to prevent crystal growth from occurring on the ground before launch, which is not always standard practice for terrestrial experiments. Third, spaceflight experiments are usually launched and returned without the ability for feedback or adjustments during the flight. To address these limitations, The Bionetics Corporation and MiTeGen, in cooperation with the ISS U.S. National Laboratory, developed the In Situ Space Protein Crystal Growth (ISSPCG) payload. The ISSPCG payload utilized commercial off-the-shelf hardware to dramatically reduce the time and money spent readying the experiment for spaceflight. For the experiment, ISS crew members engaged in real-time pipetting of solutions into the hardware. Astronauts with little to no pipetting experience watched brief instructional videos before the pipetting activities began, and personnel on the ground walked them through the procedures. Real-time microscopic imaging was conducted to track experiment progress, and protocol adjustments were made to maximize success. At the end of the experiment, the hardware was returned to Earth for crystal harvest and analysis. The approach, results, and lessons learned from the ISSPCG payload have applicability to a variety of other types of ISS experiments facing similar experiment design limitations.