DNA-coated nanostructures enhance CRISPR delivery and precision

A new nanostructure has been developed that could enable CRISPR genome-editing components to enter human cells more efficiently and safely.

CRISPR-based genome editing has the potential to cure diseases by modifying the DNA of patients. However, limitations to its clinical use include the difficulty in delivering the CRISPR machinery into cells. Existing gene therapy delivery methods include viral vectors (modified viruses in which disease-causing genes have been replaced by therapeutic genes) and lipid nanoparticles (spherical lipid layers that encapsulate therapeutic molecules), but their efficiency is limited by the high immune response elicited by the former, and the poor uptake of the latter. The new system – developed by researchers at Northwestern University, Illinois – is called LNP-SNAs (lipid nanoparticle-spherical nucleic acids). It consists of a layer of lipids embedded in a DNA shell, and can improve genome editing up to threefold across several human cell types.

'CRISPR is an incredibly powerful tool that could correct defects in genes to decrease susceptibility to disease and even eliminate disease itself, but it's difficult to get CRISPR into the cells and tissues that matter. Reaching and entering the right cells – and the right places within those cells – requires a minor miracle,' said Professor Chad Mirkin, director of the International Institute for Nanotechnology at Northwestern University and senior author of the study published in PNAS. 'By using SNAs to deliver the machinery required for gene editing, we aimed to maximise CRISPR's efficiency and expand the number of cell and tissue types that we can deliver it to.'

The researchers embedded the CRISPR machinery into lipid nanoparticles, and then surrounded them with short and dense stretches of DNA. This DNA coat can interact with receptors located on the surface of cells and enhances uptake of the particles. They tested the efficiency of LNP-SNAs in multiple human cell types, including skin cells, white blood cells, bone marrow stem cells and kidney cells, and found that LNP-SNAs have a better performance than standard LNPs without a DNA coat: they are less toxic, better internalised by the cells and they induce the intended genetic modifications more efficiently.

'Simple changes to the particle's structure can dramatically change how well a cell takes it up,' said Professor Mirkin. 'The SNA architecture is recognised by almost all cell types, so cells actively take up the SNAs and rapidly internalise them.'

Future studies are necessary to test the efficiency of LNP-SNAs in living organisms, but seven SNA-based therapies are already in clinical trials, including one commercialised by Flashpoint Therapeutics, a spin-off company of Northwesten University co-founded by Professor Mirkin.

Professor Mirkin added: 'CRISPR could change the whole field of medicine, but how we design the delivery vehicle is just as important as the genetic tools themselves. By marrying two powerful biotechnologies – CRISPR and SNAs – we have created a strategy that could unlock CRISPR's full therapeutic potential.'