Figure 4
Observation of the behavior of actual blood products (processed in a BD CPT Vacutainer tube using terrestrial density-gradient centrifugation) during 1g level flight versus microgravity conditions. (a) Example of processed blood sample in a BD CPT Vacutainer tube. (b) Greiner Laboratories LeucoSep tube designed to facilitate density-gradient centrifugation, possibly enabling such techniques to be performed in microgravity conditions. The LeucoSep tube possesses a physical porous barrier, or insert, which separates the blood (or analog fluid) above from the Ficoll solution (or analog) fluid below. A central pore (indicated) allows loading of the Ficoll solution below the barrier, and allows cellular displacement between the layers during centrifugation. Terrestrially, gravity continues to ‘assist’ in maintaining physical separation between the layered components, even after centrifugation. In the LeucoSep tube, the barrier protects the integrity of the separated components after centrifugation, a feature highly desirable for microgravity conditions. (c, d) Blood products processed and centrifuged prior to flight via standard Ficoll DGC in, from left to right: a 15 ml conical tube; a 15 ml SepMate tube; a 12 ml LeucoSep tube; and via the BD CPT Vacutainer tube. Representative images are shown for both level flight and microgravity parabolic flight. Tubes were flown triple-contained and video was recorded during several parabolas to ensure blood sample behavior was similar to that observed for the analog fluids used in the pipetting evaluation (Figure 3). Note the meniscus of the upper plasma layer (red arrow for the LeucoSep 12 ml tubes) is altered during microgravity conditions, but in all the tubes the fluids maintained their positions and were never displaced within the tube. CPT, cell preparation tubes.
