PDGF-B Is Required for Development of the Glymphatic System

SUMMARY

The glymphatic system is a highly polarized cerebrospinal fluid (CSF) transport system that facilitates the clearance of neurotoxic molecules through a brain-wide network of perivascular pathways. Herein we have mapped the development of the glymphatic system in mice. Perivascular CSF transport first emerges in hippocampus in newborn mice, and a mature glymphatic system is established in the cortex at 2 weeks of age. Formation of astrocytic endfeet and polarized expression of aquaporin 4 (AQP4) consistently coincided with the appearance of perivascular CSF transport. Deficiency of platelet-derived growth factor B (PDGF-B) function in the PDGF retention motif knockout mouse line Pdgfb ^ret/ret suppressed the development of the glymphatic system, whose functions remained suppressed in adulthood compared with wild-type mice. These experiments map the natural development of the glymphatic system in mice and define a critical role of PDGF-B in the development of perivascular CSF transport.

Graphical Abstract

In Brief

Munk et al. unravel the developmental profile of the glia-lymphatic (glymphatic) system. Glymphatic function arises in the hippocampus at postnatal day 1 in conjunction with the polarized expression of AQP4 at astrocyte endfeet. PDGF-B signaling is implicated in normal glymphatic function, and reduced signaling reduces AQP4 polarization and glymphatic influx.