Culture models to study leukocyte trafficking across the choroid plexus

We have developed a porcine and human “inverted” culture insert system that enables leukocyte transmigration specifically from the physiologically relevant basolateral side. The models use primary porcine choroid plexus epithelial cells (PCPEC) and human choroid plexus papilloma cells (HIBCPP). As a prerequisite for a functional barrier, we optimized culture conditions in which cells are maintained in serum-containing medium until high barrier function is reached. Leukocyte transmigration through the plexus epithelial cells is analysed by three-dimensional Apotome？-imaging and electron microscopy, and the route of transmigration through the plexus epithelial cells, i.e. transcellular as well as paracellular, can be determined.As a functionally relevant porcine and human BCSFB model, PCPEC and HIBCPP respectively, offer a wide range of options for analysis of disease-related mechanisms at the choroid plexus epithelium, especially involving human pathogens. Moreover, our in vitro models facilitate the investigation of leukocyte entry into the CNS via the blood-CSF barrier.The central nervous system (CNS) is separated from the blood by specific cellular structures including the blood-brain barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier (BCSFB). Whereas the endothelial cells of the brain microvasculature form the BBB, the structural basis for the blood-CSF barrier is the choroid plexus epithelium. The epithelial cells of the choroid plexus are closely connected to each other by a belt of tight junctions (TJs). TJs of epithelial and endothelial cells maintain the asymmetry of the plasma membrane and serve as a regulated permeability barrier for paracellular transepithelial and transendothelial transport of physiologically important solutes, the penetration of microorganisms and other antigenic material [1]. Other important functions of the choroid plexus are maintenence of homeostasis in the CNS and CSF-secretion and participation in neurohumoral brain mod