Glycocalyx and basal lamina in neurological disorders.

The blood-brain barrier (BBB) is an elegant structure composed of brain endothelial cells, pericytes, astrocyte endfeet, and non-cellular components-the glycocalyx and basal lamina (BL). By actively regulating molecular and cellular exchanges between the blood and the brain, the BBB maintains CNS homeostasis under physiological conditions. BBB disruption drives secondary brain injury after stroke and correlates with stroke outcomes. In Alzheimer's disease (AD), BBB breakdown is an early pathology and plays an important role in cognitive impairment. Previous studies mainly concentrate on how different cellular components of the BBB regulate its integrity in physiological and pathological conditions, leaving the glycocalyx and BL understudied. In this review, we elucidate glycocalyx and BL changes in neurological disorders and discuss the functional significance of these alterations. Specifically, the structure/composition of the glycocalyx and BL as well as the mechanical properties, turnover and assembly of the BL are described first. Next, we summarize how the glycocalyx and BL as well as the major constituents of the BL change in stroke and AD. The functional significance of these alterations is also discussed. Last, we review key questions that need to be answered and future directions in the field.