The use of laser capture microdissection (LCM) and quantitative polymerase chain reaction to define thyroid hormone receptor expression in human 'term' placenta

Term 'villous' placenta consists of a heterogeneous mix of different cell types comprising the trophoblast layers, villous stroma and fetal blood vessels. The importance of using techniques which allow investigation of pure populations of cells has been increasingly recognised. We demonstrate the use of laser capture microdissection (LCM) in combination with quantitative RT-PCR (QPCR) to assess the relative expression of mRNAs encoding the major thyroid hormone receptor (TR) isoforms (α1, α2 and β1) in trophoblasts (syncytiotrophoblast and cytotrophoblast layers) compared with stromal cells in human term placenta. Highly reproducible results for each gene were obtained for each placental sample studied (n=6). There was significantly less mRNA encoding TRα1 (68%; p=0.05) and TRβ1 (40%; p=0.03) in the trophoblast layer compared to the heterogeneous stromal cells. However, there was no significant difference in TRα2 mRNA expression between the two groups of cells. Conclusion: LCM with QPCR can precisely locate and accurately quantify mRNA expression in specific cell populations from placental tissue.