Stem Cells May Not be Best Tool for Cloning

Stem cells might not be the easiest way to clone animals: That's what researchers at the University of Connecticut are saying after they recently cloned mice from fully differentiated blood cells.

Differentiation refers to the process by which young cells take on specialized roles and functions, becoming one particular cell type, such as blood cells or liver cells. Stem cells are undifferentiated and have the potential to turn into one of many different kinds of cells.

This flexibility has traditionally positioned stem cells as more promising tools for cloning than fully differentiated cells.

For the last 10 years, said biologist Jerry Yang, leader of the new research effort, no one could answer the question: Could the cloned animal be produced from one of those differentiated cells? And now we have.