Chimeric Mice Prepared From Murine Embryonic Stem Cells Containing Targeted Mutation in an Adenosine Deaminase Gene

Abstract

Murine embryonic stem cell lines, when injected into blastocysts from mice with a different genetic background, may populate tissues and organs of developing pups, resulting in chimeric animals. Embryonic stem cells may contribute to the germ line of chimeras, permitting the transmission of genetic traits carried by these cells to the offspring. In addition, embryonic stem cells may be manipulated genetically in vitro; they may be mutagenized by homologous recombination with transfected DNA and then selected for specific mutations. Mouse models for human hereditary diseases may be developed from the stem cells with specific mutations. A complete deficiency in adenosine deaminase is associated with severe combined immunodeficiency in man. To develop a mouse model for the disease, we have isolated murine embryonic stem cells, which originated from the 129/Sv strain mouse, containing targeted mutation in one of the two adenosine deaminase alleles. Two of the targeted clones have been injected into the blastocysts derived from C57BL/6 mice. Three chimeras have been obtained, with the contribution from the embryonic stem cells ranging from 10 to 60%. The chimeras, some of which are now over 8 months of age, developed normally and were fertile. Homozygous mutants that are produced by breeding these chimeras would be useful in “gene therapy” experiments.