Classroom Explorations: Characteristics of Life
Stem cells are unspecialized cells that serve as the source, or "stem," for specialized cells such as heart, brain, or blood cells. Found in days-old embryos and a few adult organs, stem cells have two unique properties: they can change into other types of cells, and, theoretically, they can divide without limit.
In the first video, mouse embryonic stem cells move, grow, and divide in culture. (The video was taken over a 12-hour period.)
In the second video, you can observe beating cardiac myocytes (heart cells) that were grown from mouse embryonic stem cells. (The video is in real time.)
Cardiac myocytes were cultured from pluripotent mouse embryonic stem cells using standard techiniques. For imaging, cell aggregates were transferred to small, sterile plexiglass chambers attached to a coverslip, containing differentiation media. Cells were maintained on an inverted compound microscope in an environmental chamber kept at 37°C, 7.0% CO2. Images were taken with a 40x phase contrast objective and a digital video camera.