Northwestern scientists developed DNA-wrapped nanoparticles that triple CRISPR efficiency, paving the way for more effective gene editing therapies
Northwestern University researchers have unveiled a major breakthrough in CRISPR technology, demonstrating that DNA-wrapped nanoparticles can deliver gene editing tools with three times the efficiency of current methods. The discovery marks a step forward in making gene editing therapies safer, faster, and more accessible.
The study will be published in the Proceedings of the National Academy of Sciences on September 5th.
Lipid nanoparticle spherical nucleic acids: An exciting discovery
Lipid nanoparticle spherical nucleic acids (LNP-SNAs) are tiny structures that carry the complete set of CRISPR editing tools – Cas9 enzymes, guide RNA, and a DNA repair template – wrapped in a dense, protective shell of DNA. The DNA coating not only guides LNP-SNAs to specific organs and tissues but also facilitates their entry into cells.
The scientists conducted lab tests on various human and animal cell types. They found that the new CRISPR delivery system, involving DNA-wrapped nanoparticles, entered cells up to three times more effectively than the standard lipid particle delivery systems used for COVID-19 vaccines. This impressive efficiency, coupled with significantly reduced toxicity, and a threefold boost in gene editing efficiency, is a cause for excitement and anticipation in the scientific community.
“CRISPR is a potent tool that could correct defects in genes to decrease susceptibility to disease and even eliminate disease itself,” said nanotechnology and nanomedicine pioneer Chad A. Mirkin, who led the new study. “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. By using SNAs to deliver the machinery required for gene editing, we aimed to maximize CRISPR’s efficiency and expand the number of cell and tissue types that we can deliver it to.”
The study highlights the importance of how a nanomaterial’s structure can determine its potency. It underlies the emerging field of structural nanomedicine, pioneered by Northwestern’s Chad A. Mirkin and his colleagues.
CRISPR’s biggest hurdle: Inefficient delivery into cells and nuclei
While CRISPR can disable genes, repair mutations, and add new functions once inside a cell, it cannot enter on its own and instead relies on delivery vehicles such as viral vectors or lipid nanoparticles (LNPs).
While viruses are efficient, they can trigger an immune response in the human body, leading to painful or even dangerous side effects. In contrast, lipid nanoparticles are safer but less efficient, often becoming trapped in endosomes or cellular compartments. The new CRISPR delivery system, involving DNA-wrapped nanoparticles, offers a safer alternative, providing reassurance and confidence in its potential for gene editing therapies.
“Only a fraction of the CRISPR machinery actually makes it into the cell, and even a smaller fraction makes it all the way into the nucleus,” Mirkin said. “Another strategy is to remove cells from the body, inject the CRISPR components, and then put the cells back in. As you can imagine, that’s extremely inefficient and impractical.”
DNA-wrapped support for CRISPR
To overcome CRISPR delivery problems, Mirkin’s team turned to SNAs, which are globular, instead of linear, forms of DNA and RNA previously invented in Mirkin’s lab at Northwestern.
The spherical genetic material surrounds a nanoparticle core, which can be packed with cargo. Roughly 50 nanometers in diameter, the tiny structures possess a proven ability to enter cells for targeted delivery. Seven SNA-based therapies are already in human clinical trials, including a Phase 2 clinical trial for Merkel cell carcinoma being developed by Flashpoint Therapeutics, a clinical-stage biotechnology startup.
In the new study, Mirkin’s team began with an LNP core that carried the CRISPR machinery inside. The team then decorated the particle’s surface with a dense layer of short strands of DNA, as DNA can interact with a cell’s surface receptors, and cells readily absorb SNAs. The DNA can also be engineered to make delivery more selective.
“Simple changes to the particle’s structure can dramatically change how well a cell takes it up,” Mirkin said. “The SNA architecture is recognized by almost all cell types, so cells actively take up the SNAs and rapidly internalize them.”
Three-fold improved performance
After successfully synthesizing LNP-SNAs with CRISPR cargo, Mirkin and his team added them to cellular cultures, which included skin cells, white blood cells, human bone marrow stem cells, and human kidney cells.
The team observed and measured several key factors:
- How efficiently the cells internalised the particles
- Whether the particles were toxic to cells
- If the particles successfully deliver a gene
They also analysed the cells’ DNA to determine if CRISPR had made the desired gene edits, finding that across every factor, the system successfully delivered CRISPR machinery and enabled complex genetic modifications.
In the future, Mirkin plans further to validate the system in multiple in vivo disease models. Because the platform is modular, researchers can adapt it for a wide range of systems and therapeutic applications.
“CRISPR could change the whole field of medicine,” Mirkin said. “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.”
