CRISPR/Cas9 is an extremely powerful technology that allows scientists to easily rewrite human DNA to treat human disease. We envision that CRISPR/Cas9 technology can be applied in the therapy of all manner of disorders, from rare inherited genetic diseases such as Leber congenital amaurosis (link to https://rarediseases.info.nih.gov/diseases/634/leber-congenital-amaurosis), to common diseases such as high cholesterol and cancer.

Gene therapy for inherited retinal diseases

So far, there are limited options available for patients with blinding diseases. The approval of Luxturna for RPE65 disease was a major breakthrough for gene therapy and ophthalmology. Now, a new generation of gene editing technologies, enabled by CRISPR/Cas9, is on the horizon to treat diseases untreatable by gene therapy. A new generation of CRISPR technologies, developed by the group of David Liu at the Broad Institute of MIT and Harvard, named base and prime editors,  are even safer, more precise, more easily controlled, and more flexible in the mutations that are treatable by gene editing.

gene therapy

Base editing for inherited retinal diseases

We were one of the first to show that in vivo base editing rescues visual function in a mouse model of Leber congenital amaurosis, the rd12 model. The mice have a mutation that renders them unable to see, and by correcting the mutation by direct delivery of CRISPR/Cas9 to the eye, we restored vision, visual-guided behavior, and brain and visual cortex responses to visual input. We also showed protection of cone photoreceptors, which enable our ability to read and perceive color and is a critical unmet need for inherited retinal disease treatment.

base editing

The state-of-the-art delivery vector for genome editors is an adeno-associated virus (AAV), which can effectively transduce tissues and effect efficient genome editing. However, long-term expression of the genome editors from AAV is not ideal due to potential off-target edits, which can occur in sites of the genome similar to the therapeutic target and can compromise the therapeutic effect. In CTVR, we develop transient delivery methods to achieve efficient, precise editing without off-target effects.

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Moving to the clinic

The first CRISPR/Cas9 clinical trials for a wide range of diseases has already begun. We believe that CRISPR/Cas9 will be shown to be safe for ex vivo and in vivo human use, and we are excited for the application for untreatable diseases. With the concurrent advances in genome sequencing, we are working toward a future where a patient can be sequenced, have their mutation corrected in a laboratory with patient derived stem cells, and then have the proper CRISPR/Cas9 treatment packaged into proper delivery vectors. We pioneered an even safer editing technique using eVLPs that will improve safety in humans.

clinic

Nearly half of human genetic diseases are caused by point mutations. As such, there is an urgent need for advanced precision genome editing tools capable of efficiently and accurately correcting these mutations. Current CRISPR-Cas-based technologies, including DNA base editors (ABEs) and prime editors (PEs), are designed to make targeted single nucleotide changes without introducing double- stranded breaks, relying instead on the homology-directed repair pathway.

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Glaucoma is the second leading cause of irreversible blindness affecting over 70 million people worldwide. Glaucoma is characterized by loss of retinal ganglion axons, which send visual information to the brain. Primary Open Angle Glaucoma (POAG), a most common form of glaucoma, is often associated with increased eye pressure that can lead to axonal loss and irreversible blindness. This eye pressure is tightly maintained by specialized tissue called trabecular meshwork. In POAG, there is increased eye pressure due to the damage to trabecular meshwork.

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Usher Syndrome (USH) is a genetic disorder characterized by progressive hearing and vision loss, with an estimated prevalence of approximately 1 in 20,000 individuals. The most common subtype, Usher syndrome type II (USH2), is primarily associated with mutations in the USH2A gene, which cause Usher syndrome type IIA (USH2A). USH2A mutations account for over half of all USH2 cases and are strongly linked to retinitis pigmentosa. Efforts to develop treatments for USH2A-related disease face significant challenges due to the gene’s large size, extensive mutational spectrum, and limited understanding of its pathogenic mechanisms. Currently, no approved treatments exist to alleviate the retinal symptoms associated with USH2A mutations.

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We are currently working toward treatments and cures for Leber congenital amaurosis, Stargardt disease, retinitis pigmenotsa, and age-related macular degeneration.

Selected Works

Holubowicz, R., Du, S.W., Felgner, J. et al. Safer and efficient base editing and prime editing via ribonucleoproteins delivered through optimized lipid-nanoparticle formulations. Nat. Biomed. Eng 9, 57–78 (2025). https://doi.org/10.1038/s41551-024-01296-2

Arantes P.R., Chen X., Sinha S., Saha A., Patel A., Sample M., Nierzwicki L., Lapinaite A.*, Palermo G*. Dimerization of the deaminase domain and locking interactions with Cas9 boost base editing efficiency in ABE8e. Nucleic Acids Res. (2024 Dec11) PMID: 39569582 https://academic.oup.com/nar/article/52/22/13931/7906235

Suh S., Choi E.C., Raguram A., Liu D.R., Palczewski K. Precision genome editing in the eye. Proc. Natl. Acad. Sci. U.S.A.(2022) PMID: 36122230 https://www.pnas.org/doi/10.1073/pnas.2210104119

Choi, E.H., Suh, S., Foik, A.T. et al. In vivo base editing rescues cone photoreceptors in a mouse model of early-onset inherited retinal degeneration. Nat Commun 13, 1830 (2022). https://doi.org/10.1038/s41467-022-29490-3 

Banskota S., Ragguram A., Suh S. et al. Engineered virus-like particles for efficient in vivo delivery of therapeutic proteins. Cell 185 (2), 250-265 (2022).  https://doi.org/10.1016/j.cell.2021.12.021 

Suh, S., Choi, E.H., Leinonen, H. et al. Restoration of visual function in adult mice with an inherited retinal disease via adenine base editing. Nat Biomed Eng 5, 169–178 (2021). https://doi.org/10.1038/s41551-020-00632-