Construction and validation of a placental tissue microarray from specimens of well-documented preeclampsia patients

Construction of tissue microarray (TMA) to validate the very large number of molecular targets of gene microarray data may provide a high throughput approach in preeclampsia study. However, the intricate structure of the placenta has limited this technique's application. In this study, 80 preeclampsia and 58 normal placental specimens were selected for constructing TMA from 400 donor block according to strict criteria. Each specimen with enough tissue area was punched 3 cores (0.6 mm in diameter each). Two pathologists marked the representative area exactly on H&E stained slide of each donor block. Then, the target tissues on the donor block were marked carefully along with the marked area on the slide. The TMA of preeclampsia were successfully constructed. H&E staining showed 98.97% (97/98) of villous cytotrophoblast (VCT) samples and 86.36% (76/88) of extravillous cytotrophoblast (EVCT) samples retained target tissue in TMA. In all cores, the area stained positive for cytokeratin was negative for vimentin, which is the characteristic of cytotrophoblast. For EVCT TMA, the expression of HLA-G in preeclampsia was significantly lower than that of normal pregnancy (p = 0.008), which was consistent with previously reports. This study showed that it is feasible to construct high quality of placental TMA for preeclampsia study.