Crossing the rubicon

Abstract

A viral vector injected intravenously in mice crosses the blood-brain barrier and transduces widespread regions of the brain and spinal cord.

Figure 1

Developmental changes in the structure of the blood–brain barrier and the brain extracellular matrix likely influence the capacity of AAV9 to transduce different types of brain cells. Transduced cells are shown in green, non-transduced cells in gray. In neonates (left), AAV9 crosses an immature endothelium and diffuses through a lax extracellular matrix to transduce neurons, astrocytes and microglia. In adults (right), the brain endothelium has become a tight barrier surrounded by a cuff of closely packed astrocyte end feet. AAV9 can still cross the brain endothelium but does not seem able to get beyond the glial barrier, thus transducing mainly astrocytes (presumably by infecting end feet) and endothelial cells, and possibly pericytes and perivascular macrophages, but only very few neurons or microglia.