Peptide-Assisted Genome Editing (PAGE) increases efficiency and reduces toxicity of CRISPR-Cas genome editing

A recent study presents a new method called Peptide-Assisted Genome Editing (PAGE). It is an enhanced CRISPR-Cas system and allows for efficient and safe gene editing in primary human cells, including T cells, and haematopoietic progenitor cells, with high editing efficiencies of up to 98%.
Illustration showing a Cas protein recognising and cuting DNA.
In the CRISPR-Cas system, the Cas protein recognises and cuts target DNA during genome editing. Improving the efficiency of this process reduces the chances of untargeted DNA being cut.

CRISPR-Cas base genome editing technology has enabled new avenues in research and medicine. For biology and life-science research, CRISPR-Cas has been crucial to understand the functions of genes and cellular pathways.

For medicine, CRISPR-Cas has opened new therapeutic strategies to reverse genetic diseases. However, experts believe that CRISPR-Cas is not yet at its full potential 1.

A key challenge faced by researchers is to efficiently and safely deliver CRISPR components into cells, especially primary cells (cells freshly isolated from live tissue). Different delivery methods have been proposed and applied by researchers, but maximum efficiency and safety have not yet been achieved 2.

In a recent research paper, published in Nature Biotechnology, scientists report the development of a new method called Peptide-Assisted Genome Editing (PAGE) 3. When compared to standard CRISPR delivery, this enhanced CRISPR-Cas system increased the efficiency of gene-editing in primary cells by more than 80%.

The PAGE system has two important components: a cell-penetrating Cas protein (such as Cas9 or Cas12a) and a cell-penetrating endosomal escape peptide. The Cas protein is a type of protein that can make precise changes to the genetic material. The endosomal escape peptide helps the Cas protein enter the cells more easily. These components work together to make the genome editing process more efficient.

The researchers found that by mixing these two components for just 30 minutes, they were able to increase CRISPR delivery efficiency and accuracy. They tested the system using both the Cas protein alone and a Cas protein complexed with another molecule called the Cas RNP complex. In both cases, the PAGE system was successful in efficiently editing genes.

One important aspect of this study is that the researchers wanted to make sure that the process did not harm the cells or cause any problems with the way genes are normally used in the cells. They found that the PAGE system caused minimal toxicity, which means it did not harm the cells, and it did not disrupt the normal functioning of the genes.

To demonstrate the effectiveness of the CRISPR-PAGE system, the researchers used it to edit genes in two types of primary human cells: T cells and haematopoietic progenitor cells. Results from both these primary human cells showed highly efficient gene editing.

Overall, this study shows that the PAGE system is a promising method for editing genes in primary cells. The method is an improvement over existing CRISPR delivery methods to improve efficiency of gene editing and minimising toxicity. It is easy to use, effective, and safe, and it has the potential to be used in various applications where precise genetic modifications are needed.

According to the authors, a limitation to PAGE mediated gene editing could be pre-existing immunity against components of the CRISPR-PAGE system. This would essentially render PAGE unfit for in vivo (in patient) delivery. More research is needed to fully evaluate this limitation. However, for gene editing in cells (and primary cells) that have been removed from the body, immunity is not a problem. Having said that, extensive testing and validation of this new method is, obviously, warranted.

The authors conclude their paper by writing,

Collectively, PAGE provides a generalizable platform for the delivery of genome editing proteins in a rapid and highly efficient manner to help fostering the next wave of genome engineering focused on primary cells.


  1. Joy Y. Wang and Jennifer A. Doudna, CRISPR technology: A decade of genome editing is only the beginning. Science. 379, (2023).
  2. Hao Yin, Kevin J. Kauffman and Daniel G. Anderson, Delivery technologies for genome editing. Nature Reviews Drug Discovery. 16, 387-399 (2017).
  3. Zhen Zhang et al., Efficient engineering of human and mouse primary cells using peptide-assisted genome editing. Nature Biotechnology. (2023).
Photo of Sampath Amitash Gadi, author at
Sampath AmitashGadi, Ph.D.
Editor at

Sampath works as a DNA researcher at the University of Copenhagen. Right now, he is studying how proteins and protein signaling help with DNA Damage in cells.

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