Title : Mitigate cross-contamination hazards by sorting samples within a closed cartridge
Abstract:
Background: The isolation of pathogens and immune cells from hazardous samples is essential for immunological and infectious disease research. However, traditional droplet-based cell sorters pose risks of aerosol formation, exposure to infectious materials, and cross-contamination. The MACSQuant® Tyto® Cell Sorter, a benchtop microfluidic instrument, mitigates these risks through its single-use, closed-cartridge system.
In this study, we show that the MACSQuant Tyto Cell Sorter effectively contains particles as small as 1 μm and enables high-purity sorting of E coli without cross-contamination between samples.
Methods: To assess aerosol containment, a solution of 1, 2, and 10-μm Polysciences Fluoresbrite® YG Microspheres was transferred to a cartridge at 300 mbar. After sorting, the negative-chamber air filter was excised and examined using fluorescence microscopy.
Disposable Cyclex-D impactors were used to collect 1-μm microspheres during sorting, with an ultrasonic atomizer as a positive control and PBS as a negative control. The Cyclex-D was positioned above the negative-sort chamber filter while 5 mL of sample was processed. After collection, the Cyclex-D coverslip was removed and placed adhesive-side down on a microscope slide to assess particle transfer.
To test cell sorter cross-contamination, GFP-expressing E. coli (36% GFP+ in a 1 × 10?/mL suspension) was mixed with wild-type E. coli and sorted. Following GFP+ bacteria sorting, a new media-containing MACSQuant Tyto Cartridge was processed for two hours. A bioburden test was then performed, followed by 14 days of culture to detect any contamination.
Results: The microspheres were easily distinguished from other particles at 10x due to their uniform shape, size, and bright fluorescence. Fluorescence microscopy confirmed no detectable microspheres in bead-containing cartridges or negative controls, while positive controls showed abundant microspheres.
E. coli sorting achieved 97% purity, and the bioburden test showed no bacterial cross-contamination (<1 CFU/mL).
Conclusions: These findings confirm that the MACSQuant Tyto Cell Sorter’s closed-cartridge system effectively contains particles ≥1 μm, encompassing various prokaryotic and eukaryotic cells. Furthermore, it enables high-purity bacterial sorting with no cross-contamination, reinforcing its suitability for handling infectious and biohazardous samples safely.
