Four embryonic stem (ES) cell lines, designated CE1, CE2, CE3 and CE4, were isolated from C57BL/6J blastocysts. The ratio of normal diploid composition of these cell lines is above 70%. To examine the differentiation potential of the ES cells, the CE2 cells were injected subcutaneously into syngenic mice, and many kinds of differentiated cells were observed on the sections of the teratoma derived from this ES cell line. On the other hand, to test the chimeric ability of the ES cells, the CE2 cells were microinjected into the blastocysts of ICR mice, and a chimera was obtained among living pups. These results show that CE2 ES cells are pluripotent stem cells, which can differentiate into many kinds of cell types, and can be used as a cell system for further research.
Embryonic stem cells (ES-5) were transfected with PSV 2-neo-EJ-Ras and the cell colonies were chosen in the selection medium containing Geneticin. Southern-blot analysis showed that all the transfected cells possessed the whole EJ-Ras DNA. Northern-blot analysis demonstrated that the selected clones express higher level of Ras mRNA than the control. When the transfected ES-5 cells were injected into the flanks of nude mice, they formed bigger tumors and more stem cell nests were found. The chimeric ability of the transfected ES-5 cells decreased when the cells were injected into the blastocysts which were then transferred back into the uterine of foster mother. We propose that the over-expression of EJ-Ras in ES-5 cells increase the proliferation ability but decreases the chimeric potential of cell.
The aim of the present investigation was to determine if embryonic stem (ES) cells could be isolated from outbred mouse embryos (KM) and if chimeras could be producedly using outbred ES cells. Three ES cell lines,designated KE1, KE2, and KE5,were isolated from 5 Kunming albino blastocysts. Normal diploid composition of these cell lines was above 70%. By using C57BL/6J and 615 blastocysts as host embryos, one chimera was obtained in living pups. It was shown for the first time that chimeras can be produced by using outhred ES cells. This work implies that to establish ES cell lines from other animal embryos is possible. More interestingly, white color dots from ES cells on the coat of this chimeric mouse enlarged a lot after half a year, indicated that ES cells were inhibited by cells from outbred mouse or the cells of outbred mouse grew vigiously.
