ABSTRACT
The basement membrane is a specialized extracellular matrix between the epithelium and the mesenchyme.In stratified epithelium,only the basal cells in contact with the basement membrane exhibit the apical-basal polarity,whereas the epithelial cells do being not in contact with the basement membrane do not exhibit the apical-basal polarity.The basement membrane plays an important role in epithelial cell polarization.It is an important extracellular matrix(ECM)structure in the multicellular organisms,is situated between the epithelium and the mesenchyme,and is produced jointly by the epithelial cells and mesenchymal cells.Its components mainly include Laminin,type Ⅳ collagen(Col-Ⅳ),nidogen(NDG),and heparan sulfate proteoglycans(HSPG),and each component plays the different role in influencing the epithelial cell polarity.The network scaffold formed by Col-Ⅳ and Laminin is the main structure of the basement membrane,and the integrity of the structure affects the epithelial cell polarization.This review summarizes the composition and structure of the basement membrane,focuses on its role in epithelial cell polarization and its mechanism,and compiles the current status of biomimetic basement membrane materials that promotes the epithelial cell polarization,and provides the theoretical foundation for further exploration of the establishment and maintenance of epithelial cell polarity.
ABSTRACT
High extracellular potassium can induce spreading depression-like depolarizations, elevations of extracellular glutamate and even neuronal death in normal brain. To investigate the contribution of high potassium in vivo, a microelectrode arrays ( MEAs ) probe integrated with recording sites for glutamate concentration (50í150 μm) and local field potential ( LFP) ( diameter=15 μm) was fabricated by Micro-electro-mechanical-systems ( MEMS) technologies. We implanted the MEA probe acutely in the rat brain and exposed the brain to a high potassium solution. During these multi-modal recordings, it was observed that high potassium elevated extracellular glutamate while suppressing the LFP irreversibly. This is one of the first studies in which a dual mode MEA probes is applied in vivo for neuronal death, and it is concluded that our MEA probes are capable of examining specific spatiotemporal relationships between electrical and chemical signaling in the brain.