Figure 3.

Enumeration of circulating multiple myeloma cells immediately after injection (A) and over the course of the disease and following treatment (B) by IVFC. A. Treatment with anti-VLA-4 antibody significantly prolonged the circulation time of multiple myeloma cells after injection. DiD-labeled MM.1S cells injected into the tail veins of BALB/c mice were dramatically depleted from the circulation within an hour of injection unless homing was abrogated by treatment with an agent that interferes with binding through the CXCR4/SDF-1 pathway, such as anti-VLA 4 antibody (control, n = 4 mice; VLA 4 antibody treated, n = 2 mice). For every data point, at least three 60-second measurements were taken per mouse over a five-minute period, counted using Matlab, averaged and plotted above. Bars indicate standard errors. B. The number of circulating GFP+ multiple myeloma cells increased during tumor growth, but decreased in response to therapy. Weekly in-vivo flow cytometry sessions were repeatedly performed on three SCID/Bg mice that had been injected with MM.1S-GFP+ cells. For each weekly measurement, ten one-minute traces were taken, the number of GFP + cells were counted, averaged and plotted against time. Beginning in the sixth week post cell injection, bortezomib was administered twice-weekly at the clinically relevant concentration of 1 mg/kg. Solid line indicates cell counts accumulated before the mice were treated. Dashed line indicates cell counts after twice-weekly bortezomib treatment. Figure 3A,B reproduced from [14] with permission.