Delivering CRISPR components into specific cells while minimizing off-target effects remains a major challenge. Current methods rely on viral vectors such as adeno-associated viruses (AAVs) and lipid nanoparticles (LNPs), which can trigger immune responses and lead to unintended genetic alterations in non-target cells.
A research team, led by scientists from Shanghai Jiao Tong University and Fudan University, have engineered a new delivery system called RIDE (ribonucleoprotein delivery via engineered virus-like particles). Unlike traditional viral vectors, RIDE can be customized to target specific cell types while delivering CRISPR-Cas9 ribonucleoproteins (RNPs) with efficiency comparable to AAVs and lentiviral vectors but without integrating into the host genome – reducing the risk of long-term genetic alterations and immune system activation.
The study tested the RIDE system in two disease models: retinal vascular diseases and Huntington’s disease. In the retinal model, VEGF-A, a key driver of pathological blood vessel growth in conditions such as age-related macular degeneration (AMD), was precisely edited using RIDE. After subretinal injection in mice, RIDE-mediated CRISPR delivery reduced VEGF-A levels and significantly suppressed abnormal blood vessel growth with minimal off-target effects.
For Huntington’s disease, the researchers developed a neuron-specific version of RIDE by incorporating a rabies virus glycoprotein, allowing it to target neurons in the brain. When injected into the striatum of Huntington’s disease model mice, RIDE successfully edited the mutant huntingtin gene, reducing its expression without causing neuronal toxicity. Behavioral tests showed that treated mice exhibited improved motor function, indicating a potential therapeutic benefit.
A major concern with gene editing therapies is the potential for immune activation. The study found that RIDE evoked a lower immune response compared to conventional lentiviral and AAV-based CRISPR delivery methods, and it did not induce Cas9-specific immune responses. Notably, long-term studies in mice and non-human primates showed no significant adverse effects, highlighting its potential safety profile.
The researchers also tested RIDE in human induced pluripotent stem cell (iPSC)-derived neurons from Huntington’s disease patients. The system achieved a high editing efficiency at the HTT locus while exhibiting minimal off-target activity, highlighting its potential for future clinical applications.
The study concludes, “Targeted delivery is essential to improve the safety and efficacy of CRISPR therapeutics. Our study exemplified the therapeutic potential of RIDE in retinal vascular disease and Huntington’s disease models via localized delivery. Meanwhile, we speculate that RIDE can further be expanded to systematic delivery.”
According to the team, RIDE could also be reprogrammed to target a wide range of cell types, including dendritic cells, T cells, and neurons.
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