. New neurons follow the flow of cerebrospinal fluid in the adult brain. Science. 2006 Feb 3;311(5761):629-32. PubMed.

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  1. In this paper, the authors track the migration of neuroblasts from the subventricular zone in adult mice and show that they are propelled rostrally within the CSF of the lateral ventricles by directional movement of cilia on ependymal cells and by concentration gradients of guidance molecules produced by the choroid plexus. This well-performed and rather ingenious study has implications for the possible migration of therapeutically implanted stem cells in neurodegenerative disease and for the general approach to communication within the CNS.

    Although the most prominent communication system in the CNS involves one-to-one direct connections between neurons, there are also the all-important communication systems based on fluid flow or diffusion. Beyond the blood-brain barrier, interstitial fluid and solutes first diffuse between cell processes [1,2] and second, travel out of the brain by bulk flow along capillary and artery basement membranes [2,3]. Both these communication systems are disrupted in Alzheimer disease by the deposition of amyloid-β either as plaques in the brain parenchyma [4,5] or in vessel walls as cerebral amyloid angiopathy [6,7]. The third fluid system is CSF, and this is separated to some extent from interstitial fluid and perivascular drainage pathways in the human brain by leptomeninges [8]. Motive forces for the circulation of CSF and for the drainage of ISF appear to be derived from pulsations in blood vessels [9,10].

    However, from the paper by Sawamoto et al., it is clear that the actions of cilia and chemo-attractants (or in this case “chemo-distractants”) play important roles in the migration of cells in the CSF of the ventricles. It will be interesting to see whether these mechanisms can be exploited to enhance the delivery of cells to the brain via the CSF by invasive or non-invasive routes [11].

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