Authors: Basu Jayasri, Encalada Diane M, Wu Yingyi, Oraee Sara, Mishra Aruna, Mikhail Magdy
Introduction: We investigated whether placental tissue sampling site influences placental protein expression outcomes. Vascular endothelial growth factor (VEGF), VEGF165 and VEGF165b proteins were selected as candidate proteins and term delivered placentas from normotensive women was investigated.
Methods: Maternal side of each 26 placentas was divided into four quadrants: North-East quadrant was designated Q1, South-East as Q2, South-West as Q3 and North-West as Q4. Chorionic villi (CV) were isolated from placental sections of each quadrant. Pieces of CV from each quadrant were placed in separate tubes pre-labeled with placental ID and quadrant number. Tubes were stored at -80o C until assay. Monoclonal antibody based ELISA kits from R&D Systems were used to determine protein expression. The vascular pattern of each placenta was also analyzed. For statistical analysis, ANOVA and Pearson's correlation were used. P<0.05 was considered significant.
Results: Analysis of 104 CV tissues showed no difference in the expression patterns of VEGF165 and VEGF165b proteins between the four quadrants. VEGF165 and VEGF165b proteins exert opposing effects on angiogenesis, yet the two proteins were significantly correlated (r2
=0.527, p=0.0001). Dispersal type of placental vasculature was dominant compared to magistral type.
Conclusions: The study validates that VEGF165 or VEGF165b proteins expression remain unchanged irrespective of the site from where the tissues are sampled. The significant correlation between the two proteins suggests, that angiogenic modifications of placental vasculature that enables maximum blood to flow through in the third trimester of human pregnancy, is dependent on the synergistic actions of these two proteins. The existence of VEGF165b protein in amounts higher than that of VEGF165 substantiates its potential role in human pregnancy. The coexistence of VEGF165b protein in placental tissue could be a physiological phenomenon to restrain overexpression of VEGF165 during placental development, which if left unchecked, could lead to pregnancy-related complications.
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