In the evolving field of biotechnology, genome-editing technologies hold the potential to offer revolutionary solutions for human health. Among these technologies, the CRISPR-Cas9 system stands out for its ability to target and edit DNA sequences with high precision, making it a promising tool for the treatment of genetic diseases. However, existing CRISPR-Cas9 systems face obstacles such as off-target editing, limited efficacy in certain cell and tissue types, and stability issues, which hinder broader and more effective applications. To overcome these limitations, scientists are conducting innovative studies to develop more stable, specific CRISPR-Cas9 variants that can operate across a wide range of temperatures.
Chen and his colleagues aimed to develop a more effective and versatile CRISPR genome-editing system using a thermostable Cas9 enzyme and optimized lipid nanoparticles (LNP). The study introduced iGeoCas9, a CRISPR enzyme with enhanced activity and resistance to high temperatures. The research team, led by Jennifer Doudna, demonstrated that iGeoCas9 significantly increased the success of gene editing, particularly in different cell types and live models. In this study, iGeoCas9(C1) and iGeoCas9(C2), evolutionarily developed variants of the GeoCas9 enzyme, were formulated into lipid nanoparticles (LNPs) as ribonucleoprotein (RNP) complexes. This formulation optimizes intracellular transport, maximizing genome-editing efficiency.
The researchers used directed evolution to develop iGeoCas9, a thermostable Cas9 variant derived from Geobacillus stearothermophilus. They observed that this variant exhibited more than 100 times higher genome-editing efficiency compared to the wild-type GeoCas9 enzyme. Additionally, they developed LNP formulations capable of effectively packaging and delivering the iGeoCas9 ribonucleoprotein (RNP) complex, achieving efficient genome editing in various cell types, including neural progenitor cells, HEK293T cells, and human bronchial epithelial cells. Notably, two LNP formulations, named FX12 and FC8, achieved effective genome editing even at a dose as low as 100 pM. Even at this low dose, these LNP formulations showed high success in liver cells in studies targeting the PCSK9 gene, reaching up to 90% editing efficiency in HEK293T cells with these new formulations. Furthermore, genome-editing studies conducted in lung cells highlighted the genetic therapy potential for respiratory diseases. The data obtained in this study show that the new LNP formulations enable high-efficiency gene editing at lower doses compared to traditional methods.
In conclusion, this study presents a new platform in the field of genome-editing technologies using the iGeoCas9 enzyme and optimized LNP formulations. It is noted to offer broad potential in treating genetic diseases by specifically targeting tissues such as the liver and lungs. The development of a thermostable Cas9 variant and its successful delivery through optimized LNP formulations stand out as a promising approach to expand the therapeutic potential of genome-editing technologies for both ex vivo and in vivo applications.
Author: Melih Soner Başbey
Editor: Fatma Duran
Reference: Chen, K., Han, H., Zhao, S. et al. Lung and liver editing by lipid nanoparticle delivery of a stable CRISPR–Cas9 ribonucleoprotein. Nat Biotechnol (2024). https://doi.org/10.1038/s41587-024-02437-3