Updated December 29, 2014.

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Stem cells are cells found in bone marrow and other organs.

They can develop into any type of tissue that exists in the fully developed body, including any kind of blood cell: red blood cells, white blood cells, or platelets.

Because of their unique, regenerative properties, stem cells offer new hope for a variety of diseases, including diabetes mellitis, stroke, osteoporosis, heart disease and, more recently, COPD. Scientists are interested in using stem cells to repair damaged cells and tissues in the body because they are far less likely than to be rejected than foreign cells that originated from another source.

There are two types of stem cells that doctors work with most in both humans and animals: Embryonic stem cells are derived from a blastocyst, a type of cell found in mammalian embryos and adults stem cells which are derived from the umbilical cord, placenta or from blood, bone marrow, skin, and other tissues.

Embryonic stem cells have the capacity to develop into every type of tissue found in an adult. Embryonic stem cells used for research develop from eggs that have been fertilized in vitro (in a laboratory).

After they are extracted from the embryo, the cells are grown in cell culture, an artificial medium used for medical research. It is atop this medium where they then divide and multiply.

Adult stem cells have been found in many organs and tissues of the body, but, once removed from the body, they have a difficult time dividing, which makes generating large quantities of them quite challenging. Currently, scientists are trying to find better ways to grow adult stem cells in cell culture and to manipulate them into specific types of cells that have the ability to treat injury and disease.

There is much controversy going on in the world of stem cell therapy and COPD. Why? While autologous stem cell treatment without manipulation is legal in the United States, without manipulation, treatments are not likely to be clinically relevant. For stem cell treatments to be clinically relevant, millions of stem cells need to be implanted into a designated recipient. Because generating millions of stem cells is difficult once they are removed from the body, scientists must manipulate them somehow to produce larger quantities. The FDA says that manipulation turns them into prescription drugs, and that this practice must therefore be tightly regulated. Stem cell advocates don't agree with the FDA's stand on this, and are currently fighting to get this changed.

Continue reading here:
The Pros and Cons of Stem Cell Therapy for COPD