Microchip Screening for Single Cell Assessment and Isolation of Serial Killing NK Cells
Quentin Verron1, Karolin Guldevall1, Ludwig Brandt1, Per Olofsson1, Lisa Liu3, Thomas Frisk1, Karl-Johan Malmberg3, Björn Önfelt1,2
1Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Solna, Sweden; 2Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, Sweden; 3Center for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
Natural Killer (NK) cells are innate lymphocytes that play a crucial role in antiviral protection and cancer immunosurveillance. Expansion and activation of NK cells is currently explored as a cell therapy with already substantial results in hematological cancers. We have previously reported an imaging-based screening platform for assessment of the cytotoxic potential of individual NK cells within larger populations. In this assay, human primary NK cells are distributed across a silicon–glass microchip containing 32,400 individual microwells loaded with tumor target cells. Through fluorescence screening and automated image analysis, the numbers of NK and live or dead target cells in each well can be assessed at different time points after initial mixing. It became evident that a small fraction of highly cytotoxic NK cells were responsible for a substantial portion of the killing. We are therefore interested in investigating more features of the most efficient killers.
As the cells are still trapped after the cytotoxic screen further characterization of the serial killing NK cells is also possible. On the one hand, we present here an automated single-cell isolation system that allows for specific retrieval and subsequent analysis of these cells. On the other hand, we are currently developing methods for investigation of the long-term outcome of the serial killing NK cells, such as proliferation or viability long after initiation of target-cell interactions. These approaches could greatly benefit clinical applications, e.g., in the generation of highly specific and cytotoxic cells for adoptive immunothera