Enzyme replacement therapy has been successful in treating one form of lysosomal storage disease called Gaucher disease. However, storage diseases that affect the central nervous system remain untreatable because it has not been possible, to this point, to get the missing enzymes past the blood-brain-barrier and into the brain.
"Our discovery allowed us to test the idea that the brain cells might be able to make use of the reintroduced enzyme to stop or reverse the damage caused by the accumulated materials," said Davidson, who also is the Roy J. Carver Professor in Internal Medicine. "In the treated mice, the affected brain cells go back to looking normal, the brain inflammation goes away and the impaired behaviors that these mice have is corrected."
To develop their gene therapy targeting system, Davidson and colleagues used a technique called phage panning to identify peptides that hone in on the blood vessels surrounding the brain. Surprisingly, they found that peptides that targeted the brain blood vessels in mice with lysosomal storage diseases were distinct from the peptides that targeted brain blood vessels in healthy mice. Moreover, the peptides that targeted blood vessels in different diseases were distinct from each other, suggesting that each disease causes specific alterations to the blood vessels.
The team modified a deactivated virus used for gene therapy so that the virus expressed copies of the unique brain-targeting peptide on its outer coat, and also carried the genetic blueprint for the missing enzyme.
The study showed that the modified virus targeted the blood vessels in the brain and caused the blood vessel cells to produce the enzyme. Most importantly, the researchers found that the enzyme was secreted into the brain tissue in sufficient quantities to correct the disease symptoms and problems.
The team was able to use this approach to treat two ty
|Contact: Jennifer Brown|
University of Iowa