2.13. In vivo tumor growth inhibition

Approximately 1 × 10⁷ NCI-H460 cells in PBS were subcutaneously injected into the right armpit of BALB/c nude mice to form xenograft. When the xenograft volume reached approximately 250-300 mm³, the mice were randomly divided into eight groups. Different formulations (PTX = 8 mg/kg and/or VEGF siRNA = 0.55 mg/kg) were injected into each mouse once for 2 days by intravenous injection. Mice tumors were measured every two days. The day before the first dose was specified as day 0. A Vernier caliper was used to measure the longest (L) and shortest (S) diameters. Tumor size was calculated according to the formula of V = 0.5LS². Two days after the last injection, the animals were sacrificed to harvest tumor tissues and fixed in 4% paraformaldehyde, then the tumors were sectioned for TUNEL assay, CD31 immunohistochemistry and hematoxylin and eosin (H&E) stain. All the stained sections were observed by using a fluorescence microscope (Olympus X71, Japan).