In the article "Co-Injection of a Targeted, Reversibly Masked Endosomolytic Polymer Dramatically Improves the Efficacy of Cholesterol-Conjugated Small Interfering RNAs In Vivo" (
An Error Occurred Setting Your User Cookie) Wong and colleagues from Arrowhead Madison Inc. (Madison, WI) present a novel strategy to overcome the difficulty in delivering high levels of a gene knockdown siRNA drug to liver cells. While the cholesterol-conjugated siRNA drug is taken up preferentially by the liver, it is encapsulated in membrane-bound globules called endosomes and cannot reach the cells' DNA to exert its gene silencing effect. The researchers co-injected a polymer with the drug that also targets the liver and, once inside liver cells, breaks open the endosomes, releasing the siRNA drug.