Establishment of a C57BL/6J ES cell line by conditioned media of rat myocardial cells

A new method of deriving ES cell lines from C57BL/6J mice was described. One C57BL/6J ES cell line (MESPU 41) was established in medium conditioned by rat myocardial cells, without the use of feeder cells and Leukemia Inhibitory Factor (LIF). The frequency of establishment was 1.0%. MESPU 41 cells was XX type. 89% of them showed karyotypically normal and stable which were rare in XX type ES cells. They can differentiate into wide types of cells and form teritocarcinoma in vivo. Chimeras were made by injecting the ES cells into blastocysts, indicating that they had the potency to participate into the development of embryos. Using RT-PCR method, we found that rat myocardial cells expressed LIF mRNA, which might suppress ES cells differentiation and stabilize X chromosome. In order to simplify the process of preparing conditioned medium, we also immortalized rat myocardial cells. These methods broadened the conditions for the establishment of ES cell lines and open up a new point to study the stability of cultured ES cells.EI04472-4763