Preeclampsia and intrauterine growth restriction are two of the most important pregnancy complications worldwide and have been associated with abnormalities in placental trophoblast turnover. Histological evidence shows that syncytiotrophoblast nuclei form specific spatial arrangements and patterns that influence the pathological appearance of some diseased placentas. It is not known whether links exist between these nuclear organisational patterns and how trophoblast cell turnover is organised and controlled.
SUN-KASH proteins are nuclear-envelope bridges responsible for the physical links between nuclei and the cytoskeleton and are required for nuclear organisation in a variety of cells. They are known to play a role in cell turnover and have been implicated in human diseases. These include the laminopathies, some of which affect another syncytium, human skeletal muscle. We propose that the SUN-KASH proteins, through their cytoskeletal interactions, are involved in syncytiotrophoblast nuclear organisation and regulation of their turnover. To examine this hypothesis we established a novel placental sampling method, fine needle aspiration, and compared it to the usual tissue block processing. Using immunohistochemistry to detect the SUN-KASH proteins and confocal laser scanning microscopy (CLSM), we show that this new method allows faster analysis of large numbers of placental villi, reduces the need to scan large areas of tissue and can be rendered in three dimensions using CLSM. Furthermore, we show that the SUN proteins SUN1 and SUN2 as well as the KASH proteins SYNE1 and SYNE2 are expressed at the nuclear envelope of the trophoblastic syncytium.