Cellular imaging and surface marker labeling of hematopoietic cells using quantum dot bioconjugates.

Jianing Zheng, Arezou A Ghazani, Qiang Song, Sawitri Mardyani, Warren C. W. Chan, Chen Wang

Laboratory Hematology, 31 Dec 2005, 12(2):94-98

Semiconductor quantum dots (qdots) are emerging as a new class of fluorescent labels. The unique optical properties of qdots make them appealing in laboratory diagnosis; however, qdot-based probes remain to be developed and evaluated for clinical laboratory applications. In this study, 2 different approaches were employed to label hematopoietic cells with qdots. The first was based on a generalized intracellular delivery of qdots using qdot-transferrin conjugates through receptor-mediated endocytosis. Hematopoietic cells from umbilical cord blood or bone marrow were successfully labeled with qdot-transferrin in cell cultures. The fluorescence signal of qdot-transferrin was detected in the cytoplasmic location. The second approach was to use qdot-antibodies for labeling cell surface markers. The monoclonal antibodies to CD5, CD19, and CD45 surface antigens were conjugated to qdots with distinct emission spectra. The qdot-linked antibodies were shown to bind successfully to specific cell markers on lymphocytes. The signal obtained from the labeling of cells was detectable by using fluorescence microscopy and flow cytometry. The qdot signals were shown to be target specific, bright, and photo stable. The results of this study demonstrated the feasibility of using qdots for cell labeling and surface marker analysis of hematopoietic cells. Given the superior optical properties of qdots as compared to conventional fluorescence dyes, the qdot-based probe offers a promising tool for hematology analysis in clinical laboratories.