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The blood-brain barrier, formed by blood vessels , protects the brain from toxins circulating in the body's blood system. It also can keep out therapeutic drugs and, when defective, biomolecules that are needed for healthy brain development. The latter is what happens in Allan-Herndon-Dudley syndrome, according to investigators from Cedars-Sinai and the University of Wisconsin-Madison. The rare, congenital syndrome causes cognitive disability, impaired speech and underdeveloped muscles, among other symptoms. Clive Svendsen, PhD, director of the Cedars-Sinai Board of Governors Regenerative Medicine Institute, said the model developed by the collaborative team's study, published May 16 in the journal  Cell Stem Cell , may shed light on other neurological conditions that involve possible dysfunctions in the blood-brain barrier. These conditions include Alzheimer's disease and Huntington's disease, which together affect millions worldwide. A related paper, involving Sve...

Neurodegenerative diseases are often associated with protein aggregates. These are clumps of proteins created when misfolded proteins -- proteins that have lost the elaborate but recognizable shape that dictates their function -- assemble together to form a highly intractable structure. Recent research has also shown that even in the absence of disease, proteins can aggregate increasingly with age. In the case of Alzheimer's the researchers investigated whether the Amyloid beta (A?) aggregates closely associated with the disease could be induced by aging seeds: proteins that clump together with age to form aggregates. This would occur through a hypothesized phenomenon called cross-seeding, where different protein aggregates can induce each other's aggregation. Crucially, the few existing examples of cross-seeding occur between disease-associated proteins. The study's experiments on  C. elegans , an organism whose limited number of cells and relative complexity makes i...