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Homologous recombination (HR) in ES cells is a reference technology to generate high-value targeted mouse models allowing to achieve highly relevant animal models for most applications, from R&D to preclinical studies.

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ES cells transfection with targeting vector
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IngGen_ES selection Targeted ES cells selection
ES cells validation
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(PCR, Southern blot, Karyotyping)
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Injection into blastocyst
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Chimeric new born mice
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Implantation into pseudo pregnant female
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m/+ and +/+ (WT) animals
Sequencing and selection of GLT animals
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  • Optimized timelines for your project.
  • Precise modification of genes (gold standard method).
  • Correct targetting is checked by PCR and southern blotting using both internal and external probes. In order to increase the GLT rate, only clones without gross karyotypic abnormalities are injected (Codner et al., 2016). This approach allows a perfect validation of the targeted alleles at the ES stage and is in accordance with the principles of the 3Rs (Replacement, Reduction and Refinement).
  • Easier genotyping as genome modifications are known. 
  • Numerous applications: humanization, monitoring of biomarker expression, labelling cell trafficking, conditional knock-out, complex model …


  • Time consuming and more expensive method compared to CRISPR/Cas9 genome editing technologies.
  • Requires good germline-competent ES cell lines (only restricted to few genetic backgrounds i.e. C57BL/6N or BALB/cN).

Note: for generation of complex mutations, ES route remains (yet!) superior to CRISPR/Cas9.

PHENOMIN expertise

  • More than 25 years of experience and more than 3,000 models successfully created through this technology.
  • Personalized genome engineering service to fit our customer needs.
  • PHENOMIN uses its experience to determine the most appropriate technology (nuclease-based or ES cell-based) for each project.
  • PHENOMIN meticulously validates all selected ES clones to ensure proper model establishement ; this allows to speed up the genotyping step to discriminate mutant from wild type animals.
  • PHENOMIN delivers selection cassette-free animals.
  • Compared to all members from the IMPC international consortium, PHENOMIN has the highest germ line transmission (GLT) rate from in house ES cells and from IKMC ES cells.
  • Increased efficiency by combining the HR with CRISPR/Cas9  in ES cells (coelectroporation of standard plasmid HR with Cas9 and gRNA plasmid) and generate large replacements that were not (easily) feasible previously.
  • Leading scientific insight & expertise in the field.
  • Continuous R&D activity to improve our gene targeting success rate and to propose the best approach to our customers.
  • Member of international consortia (near 20 different consortia) to benefit from the latest developments.


Non exhaustive list of publications from PHENOMIN scientists or collaborators and customers.