“Tanycytes, whose cell bodies line the walls and floor of the third ventricle and extend long, slim processes that terminate in ‘endfeet’ that contact these fenestrated capillaries,” act as a shuttle between the CSF and the blood, the authors wrote. The new study suggests they also act as a kind of molecular “exit ramp,” moving tau out of the CSF and into the bloodstream for disposal. When these cells become fragmented, that clearance system falters. Tau, which should be ferried away, instead lingers—much like traffic backing up when a major off‑ramp closes—allowing toxic protein species to accumulate.
“Our findings reveal a previously underappreciated, disease‑relevant role for tanycytes in neurodegeneration,” said corresponding author Vincent Prévot, PhD, of INSERM. “Focusing on tanycyte health could be a way to improve tau clearance and limit disease progression.”
Using rodent and cellular models, the researchers showed that tanycytes take up tau from the CSF and release it into pituitary portal capillaries, enabling its entry into the systemic circulation, according to the authors. When the team blocked vesicular transport in tanycytes, tau clearance from CSF to blood slowed dramatically, and tau pathology intensified. As the authors wrote, “Blocking tanycytic vesicular transport blunts CSF‑to‑blood tau efflux and potentiates tau pathology.”








