A new gene editing platform expands the scope of CRISPR gene editing

A team of Northwestern University researchers has developed a new gene-editing platform that could inform future applications of a nearly limitless library of CRISPR-based therapeutics.

Using chemical design and synthesis, the team combined a Nobel Prize-winning technology with a therapeutic technology developed in their own laboratory to overcome a critical limitation of CRISPR. Specifically, the groundbreaking work provides a delivery system for the cargo needed to create the gene-editing machine known as CRISPR-Cas9. The team developed a way to convert the Cas-9 protein into a spherical nucleic acid (SNA) and load it with essential components needed to access a wide range of tissues and cell typesas well as intracellular compartments necessary for gene editing.

The research, published today in an article titled “CRISPR Spherical Nucleic Acids,” in Journal of the American Chemical Societyand shows how CRISPR SNAs can be delivered worldwide Cell membrane and into the nucleus, while also retaining bioactivity and gene editing capabilities.

The work builds on 25 years of work by nanotechnology pioneer Chad A. Mirkin, who led research to uncover the properties of SNAs and the factors that differentiate them from their well-known linear relative, the blueprint of life. He is best known for his invention of SNAs, structures that typically consist of spherical nanoparticles densely coated with DNA or RNA, giving them chemical and physical properties radically different from naturally occurring forms of nucleic acids.

Mirkin is the George B. Rothman Professor of Chemistry at Northwestern University’s Weinberg College of Arts and Sciences and director of the International Nanotechnology Institute. He is also a professor of chemical and biological engineering, biomedical engineering, and materials science and engineering at the McCormick School of Engineering and professor of medicine at Northwestern University Feinberg School of Medicine.

There are many classes of SNAs with cores and shells of different chemical compositions and sizes, and SNAs are now being evaluated as potent therapeutics in six human clinical trials, including for debilitating diseases such as glioblastoma multiforme (a brain cancer) and various skin cancers . .

“These novels nanostructures offers researchers the opportunity to expand the scope of CRISPR by dramatically expanding the types of cells and tissues to which CRISPR equipment can be delivered,” Mirkin said. “We already know that SNAs provide privileged access to the skin, brain, eye, immune system, gastrointestinal -intestinal tract, heart and lungs. When this type of access is combined with one of the most important innovations in biomedical science in the last quarter century, good things will follow.”

In this current study, Mirkin’s team used Cas9, a protein required for gene editing, as the core of the structure and attached strands of DNA to its surface to create a new type of SNA. In addition, these SNAs were preloaded with gene-editing RNA and fused to peptides to control their ability to move across compartmental cell barriers, thereby increasing efficacy. These SNAs, like other classes of SNAs, efficiently penetrate cells without the use of transfection agents (which are often required to deliver genetic materials into cells) and exhibit high gene editing efficiencies of 32% to 47% for several human and mouse cell lines.

The research team included graduate research students Chi Huang, Zhenya (Henry) Han, and Michael Evangelopoulos.