(1) ES Cell Targeting

ES cells are totipotent embryonic stem cells that can be used to obtain mice derived from ES cells through embryo complementation. Therefore, gene editing can be performed on ES cells to obtain genetically modified mice. This method was the main method for obtaining genetically modified mice before the emergence of technologies such as CRISPR.

(2) EPS Cell Targeting

EPS cells are a type of stem cell with higher totipotency than ordinary ES cells. Compared to ordinary ES cells, they have stronger germline transmission capabilities and higher targeting efficiency. They can effectively shorten the preparation cycle of genetically modified mice and reduce preparation costs. In the preparation of gene knock-ins and conditional knockouts, the efficiency is significantly higher than the CRISPR method, making it a new and efficient strategy for the preparation of genetically modified mice. Weida's proprietary EPS technology has been successfully applied to the rapid preparation of gene-edited mice, and the research results were published in Cell in 2017 (Yang et al. 2017).

Figure 1. EPS preparation of genetically modified mice flowchart

1. Technical Process:

Vector Construction → Electroporation of ES Cells → Clone Identification → Chimera Mouse Preparation → Obtaining ES Mice

2. Technical Advantages:

Compared with CRISPR-assisted technology, it has a shorter preparation time for gene knock-ins and conditional knockouts, predictable results, and significantly higher efficiency than the CRISPR/Cas9 method.

Compared with ES technology: The targeting efficiency of ES targeting is generally at the level of one in a million, while EPS gene targeting efficiency is increased by dozens to hundreds of times. At the same time, due to its higher totipotency, EPS has stronger germline transmission capabilities, and as low as one EPS cell can obtain chimera efficiency close to 100% in one step, saving the germline transmission process (three months).

Multiple targeting: For complex animal models that require multiple targeting, the preparation cycle is shorter.

3. ES VS. EPS Cell Targeting Construction Strategy

Figure 2. ES VS. EPS Cell Targeting Construction Strategy

4. Successful Cases:

 Figure 3. The left image is the first-generation mouse obtained after ES targeting; the right image is the first-generation mouse obtained after EPS targeting.

References

1. Yang Y, Liu B, Xu J, et al. Derivation of Pluripotent Stem Cells with In Vivo Embryonic and Extraembryonic Potency. Cell. 2017, 169(2):243-257.e25.