Expression of vascular endothelial growth factor and microvessel density in gerbil model with inoculated hepatic alveolar echinococcsis

Abstract

Objective To study the expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD, CD34) in inoculated hepatic alveolar echinococcsis gerbil model and explore the clinical significance. Methods Sixty healthy gerbils were randomly divided into model group, control group and sham operation group. Each gerbil in both model and control groups had liver vaccination with 0.1 ml immature alveolar echinococcus protoscolex suspension or 0.1 ml phosphate buffered saline by open abdominal surgery, respectively, and the sham operation group only had abdominal surgical procedures. Gerbils were put to death on the 120th day post operation, extracted the eyeball and drawn the blood. The alveolar hydatid tissue, surrounding and distal liver tissue were removed from the model group, and normal liver tissue was collected from the other two groups. The VEGF and MVD-CD34 expression was detected by immunohistochemistry staining, Western Blot, and enzyme-linked immunosorbent assay (Elisa). Results Liver alveolar echinococcsis tissue was only observed in model group. The VEGF expression was observed as yellow or brown yellow granules located in the cytoplasma. The VEGF score and VEGF/β-actin ratio in the different parts were 5.13±1.81 and 1.12±0.05, 4.20±1.52 and 0.91±0.02, 2.46±1.06 and 0.28±0.02, 2.20±0.77 and 0.30±0.02, 2.13±1.72 and 0.25±0.01, respectively. The VEGF expression in different histological sites showed a gradient change, and bubble hydatid tissues had the highest VEGF expression (P<0.05). CD34 was expressed in alveolar hydatid tissue and surrounding liver tissue in model group and the CD34 positive cells was stained brown, while CD34 was mainly located in the cell membrane of endothelial cells. The CD34 scores and the CD34/β-actin ratio in the different parts were 5.06±2.46 and 0.66±0.01, 2.43±1.26 and 0.58±0.02, and the other tissues did not have CD34 expression. The alveolar hydatid tissue had higher CD34 expression than any other tissues (P<0.05). The respective serum VEGF and CD34 level in each group was (106.17±14.17)pg/ml, (38.13±21.36)pg/ml, (42.88±17.25)pg/ml, and (1.47±0.28)ng/ml; (0.82±0.12)ng/ml, (0.72±0.16)ng/ml, both are higher in model group than those in the other groups with statistical significance (P<0.05). Conclusion Angiogenesis is detected in gerbil alveolar hydatid tissues, which might be involved in the infiltrating growth of alveococcus. Key words: Alveolar echincoccosis, hepatic; Vascular endothelial growth factor; Microvessel density; Angiogenesis