Quantum dot labeling and tracking of human leukemic, bone marrow and cord blood cells

Quantum dots (QDs) are nanometer scale fluorescent semiconductors that are increasingly used as labeling tools in biological research. These nanoparticles have physical properties, such as high quantum yield and resistance to photobleaching, that make them attractive molecular probes for tracking hematologic cells. Here, we show that QDs attached to a transporter protein effectively label all hematologic cells tested, including cell lines and malignant and non-malignant patient samples. We demonstrate that dividing cells can be tracked through at least four cell divisions. In leukemic cell lines, some cells remain labeled for 2 weeks. We show that QDs can be used to follow cells as they differentiate. QDs are seen in monocyte-like and neutrophil-like progeny of labeled HL-60 myeloblasts exposed to Vitamin D analogues and DMSO, respectively. QDs are also observed in monocytes generated from labeled CD34+ cells. In addition, QDs attached to streptavidin can target cells with differing cell surface markers, including CD33. In summary, QDs have the ability to bind to specific cells of interest, be taken up by a diverse range of hematologic cells, and followed through many divisions and through differentiation. These results establish QDs as extremely useful molecular imaging tools for the study of hematologic cells.