As reported in the Aug. 9 issue of the Proceedings of the National Academy of Sciences, researchers have now performed a careful, comprehensive study to see how negatively charged lipids stick to negatively charged DNA and self-organize into structures.
"Many research groups have made concoctions with ingredients in different proportions and then assessed their effectiveness in gene delivery, but this is hard and requires a lot of intuition," said Gerard Wong, a professor of materials science and engineering, physics, and bioengineering at the University of Illinois at Urbana-Champaign, and corresponding author of the paper.
"By understanding some of the physics, we now have recipes for assembling delivery systems with different structures, which can have intrinsically different, controllable DNA delivery efficiencies," Wong said. "We found that the same family of structures are generated for many different ions."
Gene therapy is one of the most promising strategies for developing cures for many hereditary and acquired diseases. Protocols have been approved for treating cancer, cystic fibrosis and neuromuscular disorders, for example, but delivering DNA to the proper location and getting the right amount of DNA expression without killing innocent cells has become the Achilles' heel in DNA delivery.
Positively charged (cationic) synthetic molecules will readily bond to negatively charged DNA molecules and have been used for DNA delivery, but these cationic molecules are often toxic to cells, Wong said. An alternative is to use naturally occurring negatively charged (anionic) lipids that won't harm cells.