Ablation of astrocytic laminin impairs vascular smooth muscle cell function and leads to hemorrhagic stroke

Astrocytes express laminin-111 and 211 and assemble basement membranes (BMs) at their endfeet. Here the authors show that ablation of astrocytic laminin disrupted endfeet BMs and led to hemorrhage in deep brain regions of adult mice. The lack of astrocytic laminin led to impaired function of vascular smooth muscle cells, fragmentation and vascular wall disassembly where astrocytes have a closer association with VSMCs in small arterioles. Acute disruption of astrocytic laminin in the striatum of adult mice also impaired vascular smooth muscle cells function, indicating that laminin is necessary for vascular smooth muscle cell maintenance. In vitro, both astrocytes and astrocytic laminin promoted brain vascular smooth muscle cell differentiation.