Easy assessment of ES cell clone potency for chimeric development and germ-line competency by an optimized...

Area of Science:

• * Developmental Biology
• * Genetics and Genomics
• * Animal Models

Background:

• * Creating gene-manipulated mouse lineages requires germ-line competent chimeric mice derived from embryonic stem (ES) cells.
• * Blastocyst injection is a common method, but the aggregation method offers an alternative with potentially simpler execution.
• * Optimizing ES cell integration and germ-line contribution is crucial for efficient genetic manipulation.

Purpose of the Study:

• * To re-examine and improve the embryo-ES cell co-culture conditions for the aggregation method.
• * To evaluate the efficiency of germ-line competent chimeric mouse production using a modified aggregation technique.
• * To assess the variability in germ-line competency among different ES cell clones and predict their developmental potential.

Main Methods:

• * Modification of the co-culture medium for embryo-ES cell aggregation.
• * Testing of R1 ES cell and 10 gene-manipulated subclones using the modified aggregation method.
• * Classification of ES cell clones into grades (A, B, C) based on chimera contribution and germ-line transmission rates.

Main Results:

• * A simple modification to the co-culture medium significantly improved germ-line competent chimeric mouse production via aggregation.
• * ES cell clones exhibited varied efficiencies in chimeric development and germ-line transmission, even with normal morphology and karyotype.
• * Clones were categorized into three grades (A, B, C) reflecting high, moderate, or no germ-line transmission potential.

Conclusions:

• * The modified aggregation method is effective for producing germ-line competent chimeric mice.
• * This method serves as a valuable tool for predicting the germ-line competency of different ES cell clones.
• * The findings facilitate the selection of suitable ES cell lines for establishing gene-manipulated mouse lineages.