Understanding CRISPR RNP as a Next-Generation Genome Editing Strategy

Background of the CRISPR system

CRISPR system has emerged as a powerful genome engineering tool in both laboratory and GMP-compliant settings. It enables rapid, scalable, and cost-effective genome editing with high efficiency and precision, and is applicable across a wide range of cell types and organisms. CRISPR system consists of two main components: a Cas nuclease and a guide RNA (gRNA). The Cas nuclease can induce a site-specific double-strand break (DSB) guided by gRNA (Ceasar et al., 2016). This induced break is subsequently repaired by the host cell’s endogenous DNA repair machinery, primarily through non-homologous end joining (NHEJ) or homology-directed repair (HDR) in the presence of a donor template(Liu et al., 2019; Yang et al., 2020). NHEJ typically results in gene knockout, whereas HDR enables precise gene editing.

What Is CRISPR RNP?

More recently, CRISPR ribonucleoprotein (RNP) delivery method has been largely used to introduce CRISPR components into host cells. In the CRISPR RNP approach, the purified Cas nuclease protein (e.g., Cas9) and guide RNA (sgRNA or crRNA:tracrRNA) are synthesized separately in vitro and assembled into a ribonucleoprotein complex prior to delivery into target cells. Then, this pre-assembled RNP complex is directly introduced into target cells, without DNA or mRNA intermediates. Two efficient techniques are used to delivery RNPs into cells, electroporation and lipid-mediated transfection. Once inside the cells, the RNP complex binds to the genomic complementary target DNA sequence in the genome and introduce site-specific DSB which is then repaired via NHEJ or HDR. Following genome editing, the RNP complex is rapidly degraded by the host cells, thereby avoiding untargeted cleavage.

CRISPR RNP vs. Expression-Based Systems: Plasmid and mRNA Approaches

Compared with plasmid-based and mRNA-based CRISPR approaches, CRISPR RNPs show reduced off-target effects, higher editing efficiency, and rapid editing. During genome editing by CRISPR RNP in target cells, the Cas nuclease is active only transiently and is rapidly degraded after editing, the duration of nuclease activity is tightly controlled, which significantly reduces the risk of off-target cleavage(Kim et al., 2014). This transient activity also enables faster generation of edited cells or organisms compared with DNA-based approaches that require transcription and translation. In addition, RNP delivery frequently achieves higher editing efficiencies, particularly in primary cells and other cell types that are difficult to transfect using plasmid-based methods(Rathbone et al., 2022). Importantly, CRISPR RNPs are generally less cytotoxic than CRISPR plasmids, which can negatively impact cell viability(Cheng et al., 2022)

Applying CRISPR RNP to Build Reliable Custom Cell Models

In custom cell line development, reliability, precision, and turnaround time matter more than novelty. CRISPR RNP has become our preferred genome editing strategy because it delivers consistent and controllable results across diverse cell types. CRISPR RNP significantly shortens project timelines by eliminating plasmid construction and expression optimization steps. When building disease or pathway-specific cell models, maintaining genetic integrity is critical. The transient nature of CRISPR RNP helps ensure that observed phenotypes result from the intended edit rather than prolonged nuclease activity. We apply CRISPR RNP across a wide range of cell types, including those that are difficult to transfect with DNA-based systems, enabling broader customization options for our customers. For our customers, this translates into faster access to validated cell models that are ready for functional studies, drug screening, or mechanism-of-action research.

Reference

1. Ceasar, S. A., Rajan, V., Prykhozhij, S. V., Berman, J. N., & Ignacimuthu, S. (2016). Insert, remove or replace: A highly advanced genome editing system using CRISPR/Cas9. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1863(9), 2333–2344.
2. Cheng, Q., Xia, J., Wang, K., Zhang, Y., Chen, Y., Zhong, Q., Wang, X., & Wu, Q. (2022). CRISPR/Cas9 ribonucleoprotein (RNP) complex enables higher viability of transfected cells in genome editing of acute myeloid cells. Annals of Translational Medicine, 10(16), 862–862.
3. Kim, S., Kim, D., Cho, S. W., Kim, J., & Kim, J.-S. (2014). Highly efficient RNA-guided genome editing in human cells via delivery of purified Cas9 ribonucleoproteins. Genome Research, 24(6), 1012–1019.
4. Liu, M., Rehman, S., Tang, X., Gu, K., Fan, Q., Chen, D., & Ma, W. (2019). Methodologies for Improving HDR Efficiency. Frontiers in Genetics, 9, 691.
5. Rathbone, T., Ates, I., Fernando, L., Addlestone, E., Lee, C. M., Richards, V. P., & Cottle, R. N. (2022). Electroporation-Mediated Delivery of Cas9 Ribonucleoproteins Results in High Levels of Gene Editing in Primary Hepatocytes. The CRISPR Journal, 5(3), 397–409.
6. Yang, H., Ren, S., Yu, S., Pan, H., Li, T., Ge, S., Zhang, J., & Xia, N. (2020). Methods Favoring Homology-Directed Repair Choice in Response to CRISPR/Cas9 Induced-Double Strand Breaks. International Journal of Molecular Sciences, 21(18), 6461.