Aside from Frankenstein, previous attempts to make synthetic life have focused on genes. Geneticist Craig Venter and his colleagues, for example, announced in 2010 that they had created a one-celled creature by inserting an artificial genome in an existing cell that reproduced.

Now a separate team of scientists from Harvard University and the California Institute of Technology have built an eight-armed jellyfish by inserting muscle cells from a rat into a sheet of silicone.
The resulting "medusoid," as they called it, could offer insights into tissue engineering -- such as re-building a heart. And show that when building tissues, there might be several ways or materials to use other than those found in nature.To build the medusoid, the scientists mapped out the protein networks in a real jellyfish's muscle cells. They then looked at how electrical current triggers the muscle contraction.

Another piece of the puzzle was uncovering the mechanics at how jellyfish move. The animals squeezes a muscle to propel itself through the water, but it was important to study the biomechanics of the stroke in order to duplicate it.

The scientists also found that a sheet of cultured heart muscle tissue from a rat would contract when electrically stimulated in a liquid environment. By incorporating the muscle cells with a silicone polymer membrane, they were able to create a jellyfish-shaped body with eight appendages. The artificial creature was put into a container of salt water and hit with an electrical current. It started swimming just like a real animal.

The next step is making a jellyfish that engages in ordinary behaviors, such as seeking food and responding to its environment.
Study co-author Kevin Kit Parker, professor of bioengineering and applied physics at Harvard, said he got interested in the project in 2007, when he started thinking about muscular pumps such as hearts. Seeing jellyfish at the New England Aquarium inspired him: he saw that there were similarities between jellyfish and human hearts.