Removal of Human Leukemic Cells from Peripheral Blood Mononuclear Cells by Cell Recognition Chromatography with Size Matched Particle Imprints.

We report a cell recognition chromatography approach for blood cancer cell separation from healthy peripheral blood mononuclear cells (PBMCs) based on size-matched functionalized particle imprints. Negative imprints were prepared from layers of 15 μm polymeric microbeads closely matching the size of cultured human leukemic cells (HL60). We replicated these imprints on a large scale with UV curable polyurethane resin using nanoimprinting lithography. The imprints were functionalized with branched polyethylene imine (bPEI) and passivated by Poloxamer 407 to promote a weak attraction toward cells. When a matching cell fits into an imprint cavity, its contact area with the imprint is maximized, which amplifies the attraction and the binding selectivity. We tested these imprints specificity for depleting myeloblasts from a mixture with healthy human PBMCs in a cell recognition chromatography setup hosting the imprint. The mixture of fixed HL60/PBMCs ratio was circulated over the imprint and at each step the selectivity toward HL60 was assessed by flow cytometry. The role of the imprint length, flow rate, channel depth, and the bPEI coating concentration were examined. The results show that HL60 cells, closely matching the imprint cavities, get trapped on the imprint, while the smaller PBMCs are carried away by the drag force of the flow. Lower flow rates, longer imprints, and interim channel depth favor HL60 specific retention. The bPEI concentration higher than 1 wt % on the imprint made it less selective toward the HL60 because of indiscriminate attraction with all cells. Particle imprint based cell recognition chromatography was able to achieve selective myeloblast depletion from initial 11.7% HL60 (88.3% PBMC) to less than 1.3% HL60 for 3 h of circulation. The cell recognition chromatography with size-matched microbead imprints can be employed as an efficient cell separation technique and potentially lead to alternative therapies for myeloblasts removal from peripheral blood of patients with acute myeloid leukemia.