Selective and efficient tumor cell purging using large-scale scanning cytometry and laser-induced necrosis

Tumor cell contamination within harvested autologous hematopoietic stem cell (HSC) products continues to be of major concern since re-infused tumor cells are known to contribute to disease relapse. Numerous purging approaches have been evaluated, but these methods leave detectable tumor cells in the transplant and reduce HSC numbers, potentially causing engraftment delays and compromising the therapeutic value of purging. A novel approach that integrates automated scanning cytometry, image analysis, and laser-induced necrosis to kill all detectable target cells within a population is described here, as applied to tumor purging. This study utilized different types and stages of non-Hodgkinʹs lymphoma (NHL) tumor cell lines spiked into a HSC mixture. PE-conjugated antibodies against lineage-associated B-cell surface markers (e.g. CD20 and CD22) were used to label the tumor cells. Following labeling, 108 cells were spread on the surface of a custom 250 cm2 sterile container. As the container was scanned, a 10 ns focused laser pulse was fired at every target cell. The laser pulse delivers