Successive generations of mice produced from an established culture line of euploid teratocarcinoma cells

Publisher Website
Google Scholar
Abstract
The possibility of utilizing mouse teratocarcinoma stem cells as intermediaries for production of new strains of mice with preselected mutant or foreign genes requires that, after propagation in culture to allow for genetic manipulation and selection, the cells be capable of normalization and orderly development in carrier embryos and, ultimately, of germ-cell formation. A karyotypically normal teratocarcinoma culture line was recently established in this laboratory and now has been investigated as a candidate. The line, designated METT-1, is chromosomally female (X/X) and was obtained from the 129 (agouti-colored) inbred strain. The developmental potential of these cells was tested after prolonged culture and freezing and thawing by microinjecting them into early (blastocyst stage) embryos of the C57BL/6 (black) strain. Among 312 experimental animals examined at 1 wk of age, 41 mice (21 females and 20 males) displayed the coat colors of both strains. This frequency (13%) and the extent of the coat areas derived from the cell line greatly surpassed the contributions observed in all previous experiments, whether with other in vitro teratocarcinoma cell lines or with in vivo transplant lines. The developmental totipotency of METT-1 cells was evident from the presence of substantial amounts of 129-strain cells (bearing an isozyme marker) in all internal tissues of an individual whose coat was largely agouti. The culture-cell lineage was capable of giving rise to reproductively functional oocytes. Of 9 mosaic-coat females test-mated to C57BL/6 males, 1 produced progeny of the diagnostic agouti color in 2 litters; these heterozygous F1 offspring in turn transmitted their marker genes to F2 homozygous segregants. The METT-1 teratocarcinoma line bridges the gap between in vitro cell propagation and in vivo development and between the soma and the germ line. This creates the option of producing new mouse strains with predetermined genetic changes designed as probes of developmental regulation or as models of human genetic diseases.