Visualizing Human Prostate Cancer Cells in Mouse Skeleton Using Bioconjugated Near-infrared Fluorescent Quantum Dots

ObjectivesTo visualize human prostate cancer cells in mouse bone with bioconjugated near-infrared quantum dot (QD) probes. Near-infrared fluorescent probes using QDs can visualize tumors in deep tissues in vivo.MethodsHuman prostate cancer C4-2B xenografts grown in mouse tibia were detected by prostate-specific membrane antigen antibody conjugated with QDs emitting light at the near-infrared range of 800 nm (QD800). Images in culture and in vivo were acquired using the IVIS Imaging System.ResultsAs few as 5000 cells can be detected subcutaneously when tagged with QD800 conjugate and injected directly into mice. QD800 conjugate injected intravenously in mice harboring C4-2B tumors in tibia detected signals from a minimum of 500 000 cells. The maximal light emission was detected 30 minutes after intravenous injection of QD800 conjugate in mice with established C4-2B tumors.ConclusionsBioconjugated near-infrared QD probes are highly sensitive molecular imaging tools for human prostate cancer micrometastases in mice.