A rapid and simple assay for human blood malignancy engraftment, homing and chemotherapy treatment using fluorescent imaging of avian embryos

Detection of grafted human cells in mice using fluorescence is a rapid and simple technique whose use is continually expanding. Robust engraftment of human hematological malignancy (HHM) lines and patient cells into the naturally immunodeficient turkey embryo has recently been demonstrated by polymerase chain reaction (PCR), fluorescence activated cell sorting (FACS) and histology. We demonstrate here that fluorescence imaging is a rapid and simple technique for detecting engraftment and homing of cells derived from HHM in turkey embryos. Raji lymphoma cells expressing a far-red fluorescent protein were injected intravascularly into turkey embryos and fluorescence was detected 8 days later in their limbs and skulls. Much stronger signals were obtained after removal of the bones from the limbs. Unlabeled Raji cells did not give a fluorescent signal. Treatment with doxorubicin dramatically reduced the fluorescent signal. Intravenously injected HL-60 leukemia cells labeled with infrared-fluorescing dye were detected in the bone marrow after 16 h. Homing was active, although some non-specific fluorescence was present. Use of fluorescence imaging of HHM in turkey embryos is therefore feasible and reduces the time, effort and expense for detecting engraftment. This technique has potential to become a high-throughput xenograft system for hematological chemotherapy development and testing, and for study of hematological cell homing.