Figure 4

Migration of MSC in orthotopic MIA-PaCa-2 pancreatic xenografts in nude mice and the incorporation in tumour blood vessels. (A) Four mice with MIA-PaCa-2 orthotopic pancreatic cancer xenografts were injected with lentiviral eGFP-labeled MSC (4 × 10⁵ in tail vein). Four xenografted mice received PBS injection and served as controls. Three days after injection, mice were killed followed by the resection of organs and xenografts. Cells were isolated from tissue pieces and examined by flow cytometry for expression of green fluorescence of eGFP-expressing MSC. Mean bars±s.e. are shown. (B) Four xenografted mice per group were injected with PBS only (no MSC) or with MSC transduced with lentiviral control vector (VEC-CO), or with MSC transduced with lentiviral siRNA towards VEGF (siVEGF). Three days later, microvessel density in cryosections of xenografts was analysed by immunohistochemistry for CD31 in a Leica DMRB microscope with 250-fold magnification. Microvessel density was quantified using eight images from each of four different tumours per group. Microvessels per field of 1 mm² were counted. (C) Data from one representative staining per group are shown. (D) Vascular endothelial growth factor protein in supernatant of MSC transduced with lentiviral control vector (VEC-CO) or with siRNA towards VEGF (siVEGF) cultured under normoxic (white bars) or hypoxic (black bars) conditions was analysed by the ELISA assay. Statistical significance was determined by t-test (P<0.05) and is indicated by an asterisk.