Culture of Choroid Plexus Epithelial Cells and In Vitro Model of BloodCSF Barrier

Chemical homeostasis in the extracellular fluid of the central nervous system (CNS) is maintained by two brain barrier systems, i.e., the blood–brain barrier (BBB) that separates the blood circulation from brain interstitial fluid and the blood–cerebrospinal fluid barrier (BCB) that separates the blood from the cerebrospinal fluid (CSF). The choroid plexus, where the BCB is located, is a polarized tissue, with the basolateral side of the choroidal epithelium facing the blood and the apical microvilli in direct contact with the CSF. The tissue plays a wide range of roles in brain development, aging, nutrient transport, endocrine regulation, and pathogenesis of certain neurodegenerative disorders. This chapter describes two in vitro cultures that have been well established to allow for study of the BCB structure and function. The primary choroidal epithelial cell culture can be established from rat choroid plexus tissue, and a similar immortalized murine choroidal epithelial cell culture known as Z310 cells has also been established. Both cultures display a dominant polygonal morphology, and immunochemical studies demonstrate the presence of transthyretin, a thyroxine transport protein known to be exclusively produced by the choroidal epithelia in the CNS. These cultures have been adapted for use on freely permeable Transwell^� membranes sandwiched between two culture chambers, facilitating transport studies of various compounds across this barrier in vitro. These choroidal epithelia cultures with the Transwell system will perceivably assist blood–CSF barrier research.