Danish scientists develop vehicle for systemic delivery of RNAi

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Scientists at the University of Aarhus in Denmark have developed a stealth vehicle consisting of billions of nanoscale sugar crystals for transporting RNAi across the cell membrane.

The sugar, chitosan, is biocompatible, and is broken down in the body after it has delivered its payload. The discovery was made by researchers at the Interdisciplinary Nanoscience Center (iNANO) at the University of Aarhus.

The ability of the chitosan/RNAi construct to silence offending genes has been demonstrated in mice that were genetically modified by the introduction of a gene from jellyfish that made their coats green. The animals returned to their natural colour when the jellyfish gene was silenced by delivering RNAi with the chitosan vector.

While the field of RNA interference has come a very long way in the eight years since this approach to silencing genes was first suggested, the systemic delivery of RNAi has proved problematic because the molecules are broken down in the body before reaching their target.

There are clinical trials ongoing in which RNAi is being tested in the treatment of the eye disease age-related macular degeneration, but in this case the product is administered by direct injection into the eye. There are also liposomal delivery systems in late preclinical development.  

Because chitosan is naturally occurring and is completely safe for the body, the capsules can be administered via an oral spray. While cells in the lungs would normally resist the entry of the foreign substance, this is not the case with the chitosan nanocapsules.