Researchers “push the ENVLPE” with new virus-like particle to fix mutations causing blindness

UC Irvine School of Medicine researchers, in collaboration with a team from the Helmholtz Munich research institute in Germany, have developed a new virus-like particle (VLP) to enhance how specialists edit proteins causing inherited diseases. This new VLP system, called Engineered Nucleocytosolic Vehicles for Loading of Programmable Editors — or ENVLPE — efficiently corrected two mutations associated with blindness. The researchers anticipate this CRISPR approach also being used to treat other inherited diseases, such as cystic fibrosis and familial hypercholesterolemia.

“We have previously demonstrated VLPs that can efficiently deliver CRISPR prime editors to restore sight in live mice,” says Samuel Du, an MD/PhD candidate working in the Palczewski Lab and a National Eye Institute research fellow. That previous work directly fused CRISPR components to VLP structural components. However, the team at Helmholtz Munich discovered an alternative mechanism for recruiting and packaging CRISPR prime editors into VLPs, overcoming several bottlenecks in the VLP production.

“Utilizing RNA-protein interactions, the VLPs underwent several rounds of modification and optimization to create highly efficient VLPs,” says Krzysztof Palczewski, PhD, of UC Irvine’s Gavin Herbert Eye Institute Ophthalmology. “A key advantage of this system is that it is highly modular — any CRISPR system can easily be put into the ENVLPE VLPs with no complicated cloning and optimization of cleavage patterns like with other VLP systems.”

The team at Helmholtz Munich tested the ENVLPE VLPs in multiple CRISPR paradigms: gene knockout, homology-directed repair, base editing and CRISPR-activation assays. They also applied these VLPs in multiple cell types, including workhouse tissue culture lines, brain organoids and primary T cells.

To test the VLPs in a live animal, they then turned to the UC Irvine team for their expertise in visual physiology and ocular surgery. “We demonstrated that a single injection of these ENVLPE VLPs into the rd6 and rd12 mouse models of inherited retinal degenerations efficiently corrected their causative mutations,” says Du. “This led to restored protein production and vision, as measured by multiple assays.”

The findings appear in the paper “Engineered nucleocytosolic vehicles for loading of programmable editors,” published in the May 2025 issue of Cell. “We are excited to further test the ENVLPE system and investigate new models that can be treated with these VLPs,” says Palczewski. “We also hope to develop more advanced purification and characterization pipelines, moving these promising biologics closer to the clinic and developing new therapies for diseases.”

This work was supported in part by grant funding from the National Institutes of Health (NIH). Other funders included Research to Prevent Blindness, the School of Medicine Dean’s Office, the German Federal Ministry of Education and Research, the European Research Council, and the European Innovation Council.