Figure 3. Detection of residing MOPC-315.BM luc⁺ cells and in vivo monitoring of reduced myeloma progression due to melphalan treatment.

BALB/c wild type mice were injected with 1×10⁵ MOPC-315.BM luc⁺ cells via the tail vein. On day +19 after inoculation, tumors were established in all mice and readily detected by BLI. Then treatment was started ( = day 0 of treatment). Mice received 5 mg/kg melphalan (n = 9, two independent experiments) or mock treatment (vehicle control, n = 13, three independent experiments) intraperitoneally. One control group of MOPC-315.BM luc⁺ tumor bearing mice did not receive any treatment (untreated control, n = 14, three independent experiments). (A) Schematic study design, indicating treatment time points in respect to time after MM injection and end of experiment. Red arrows pinpoint melphalan treatment. (B) BLI images of two representative mice per group at selected time points in ventral (left) and dorsal (right) view. (C) Quantification of bioluminescence signal intensities over time from ventral or dorsal. Signals at day +19 were set as starting point and the following measurements were calculated as fold change of this initial signal intensity. Mice were treated at time points as indicated by arrows. Significant difference between melphalan treated mice vs vehicle control or vs untreated animals starting on day 10 of treatment for both, ventral (untreated vs melphalan p<0.0001, vehicle vs melphalan p = 0.0032) and dorsal (untreated vs melphalan p = 0.0006, vehicle vs melphalan p = 0.0024). (D) Quantification of skeletal tumor foci in untreated, vehicle control and melphalan treated mice on day 0 and 14 of drug treatment.