Arginine-containing vesicles deliver

Arginine-rich peptides have previously been shown to transport cargo into cells. Now, Timothy J. Deming and his coworkers in the department of bioengineering at UCLA have shown that they can get similar transport properties when arginine is part of a polymeric vesicle (Nat. Mater., DOI: 10.1038/nmat1794). But rather than attach a polyarginine peptide to an existing vesicle, they formed the vesicles from a polyarginine-polyleucine block copolymer. In effect, they replaced polylysine in an earlier version of the vesicles they had made with polyarginine without disrupting the self-assembly process. Although polyarginine peptides longer than 20 amino acids have shown cellular toxicity in the past, the new vesicles, which contain segments of 60 arginine units and 20 leucine units, are not toxic. The vesicles can transport dye-labeled dextran into epithelial and endothelial cells in cell culture, which the researchers monitored by fluorescence. Vesicles made with lysine instead of arginine are not taken up by cells, nor is nonencapsulated dye-labeled dextran.