Question

What is stem cell and how is it used?

Answer 1

This is the definition of a stem cell: an undifferentiated cell of a multicellular organism that is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation.

Answer 2

A stem cell can be used to help repair and re-generate damaged or lost tissue. Stem cells can be anything they want pretty much. It's a like a little kid who doesn't know what they wanna be when they grow up.

Answer 3

It's being extensively used in gene therapy. Check out the following:
Hematopoietic Stem Cell Expansion and Gene Therapy
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291512/

Answer 4

Thanks @Luigi0210 @kathy0514