Fig. 1: Primary tumor-derived EVs (pTDEs) restrict metastasis formation and growth.

a Schematic illustration of the established experimental metastasis model. The mice were inoculated with CHMp cells into the mammary fat pad to produce a primary tumor on Day 0 (n = 20). On Day 21, the primary tumors were surgically removed. Seven days after surgery, PBS (n = 4) or pTDEs (n = 5) were administered to the mice. Mice were treated with PBS or pTDEs (10 µg/mouse) through the tail vein six times every two days. b Bioluminescence images of CHMp lung metastases after surgery for confirmation of residual primary tumor mass (at D28). D33 bioluminescence images were acquired from the mice treated with PBS or pTDEs three times, and D39 images were acquired six times at two-day intervals. For each group of daily images, four mouse images were acquired at four positions (dorsal, ventral, right lateral and left lateral) to capture every possible signal from the mice. c Graph showing the quantification of lung metastases in a mouse model of metastasis treated with PBS and pTDEs. Unpaired Student’s t test was used to compare groups. (***P < 0.001) d Representative images of lungs after PBS and pTDE treatment. Top: PBS-treated samples; bottom: pTDE-treated samples. Scale bar, 2 mm. e Representative H&E staining of lung tissue (4X) from the metastasis model. The left panel shows the PBS-treated mice, and the right panel shows the pTDE-treated mice. Magnified images: Scale bar, 1 mm. The results are presented as the mean ± SD (4–5 mice were used for each group). Figure 1a was created with BioRender.com.