Demystifying CRISPR gRNA Chemical Modifications

By Rebecca Roberts, Ph.D., Kevin Holden, Ph.D., and Adrianna Zepeda

Chemical modifications on CRISPR guide RNAs (gRNAs) are essential for enhancing stability, reducing immune responses, and improving editing efficiency, particularly in challenging cells and in vivo applications. These modifications act as protective armor, preventing degradation by exonucleases and stabilizing gRNAs for effective gene editing. Synthego supports researchers by providing synthetic gRNAs with standard and highly modified structures, ensuring their suitability for clinical and research use.

CRISPR systems rely on gRNAs to guide nucleases like SpCas9 to target sequences, but the innate instability of RNA can hinder editing efficiency, especially in primary human cells. Modifications, such as 2’-O-methylation (2’-O-Me) and phosphorothioate (PS) bonds, offer stability by protecting the backbone and reducing off-target editing. These are particularly valuable for in vivo gene therapies, where gRNAs face degradation risks and immune responses during delivery.

Functional groups like fluorescent labels enable visualization of editing outcomes, while specialized modifications, such as those used in prime editing, prevent unwanted integration. For in vivo applications, highly modified guides are crucial to ensure efficient delivery, stability, and reduced immune reactions.

Synthego provides high-quality, scalable production of chemically modified gRNAs, helping researchers achieve clinical success. Their expertise in customization ensures that researchers can select the appropriate modifications for specific CRISPR applications, from gene therapies to RNA-based treatments. With cutting-edge manufacturing practices and tailored support, Synthego ensures a stable supply of clinical-grade gRNAs, helping accelerate the development of CRISPR therapies.