Monday, September 14, 2009

What are stem cells? (Side bar to Part 1)

STEM CELLS ARE the primary cells in the human body from which all other tissues “stem” from. They could be programmed in the laboratory to potentially become any other kind of cell and could be used to repair damaged tissues and replace diseased organs.

Stem cells are found in most, if not all, multicellular organisms and are characterized by their ability to renew themselves into a diverse range of specialized cell types. The field developed from the findings of Canadian scientists Ernest A. McCulloch and James E. Till in the 1960s.

There are two broad types of mammalian stem cells: Embryonic stem cells that are isolated from the inner cell mass of blastocysts, and adult stem cells that are found in adult tissues.

In a developing embryo, stem cells can differentiate into all of the specialized embryonic tissues. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells, but also maintain the normal turnover of regenerative organs, such as blood, skin or intestinal tissues.

Stem cells can now be grown and differentiated into specialized cells, among them, heart muscles, nerve cells and blood cells. Stem cells from the bonemarrow, umbilical cord blood and highly plastic adult stem cells from a variety of sources are now routinely used in a variety of medical therapies. This holds a lot of promise in treating a variety of conditions in the future, among them, Parkinson’s disease, diabetes, spinal injuries, heart disease, vision and hearing loss.

Stem cells from blood is harvested with the use of a machine to which a person is intravenously connected. White blood cells (WBC) are collected while the rest of the blood components are returned to the body. In the lab, the WBC go into a special growth broth that could be used to kill cancerous cells.
Source: National Institutes of Health resource for stem cell research