BACKGROUND: Stem cells are the body’s raw materials — cells from which all other cells with specialized functions are generated. Under the right conditions, stem cells divide to form more cells, called daughter cells. These daughter cells become new stem cells or specialized cells with a more specific function, such as blood cells, brain cells, heart muscle or bone. Stem cells are unique — no other cell in the body has the natural ability to generate new cell types. Researchers have discovered several sources of stem cells.
•Embryonic stem cells come from embryos that are four to five days old. They can divide into more stem cells or become any type of body cell. Because of this versatility, embryonic stem cells have the highest potential to regenerate or repair diseased tissue and organs.
•Adult stem cells are found in small numbers in most adult tissues. They are also found in children, placentas and umbilical cords. Until recently, it was believed that they could only create similar types of cells. For instance, it was thought that stem cells in bone marrow could give rise only to blood cells. However, emerging evidence suggests that adult stem cells may be able to create unrelated types of cells. For instance, bone marrow stem cells may be able to create muscle cells.
•Adult cells altered to have properties of embryonic stem cells through nuclear reprogramming. Scientists have successfully transformed adult cells into stem cells using this technique. By altering genes in adult cells, researchers can reprogram the cells to act similarly to embryonic stem cells. It’s not known if this will cause adverse effects in humans.
•Amniotic fluid stem cells are found in the fluid that fills the sac surrounding a developing fetus in the uterus. More study of amniotic fluid stem cells is needed to understand their potential.
DIRECT REPROGRAMMING: A goal of regenerative medicine has been to take any cell from a person’s body and turn it in to any other cell type that may be desired. This would eliminate several donor-compatibility problems, and potentially eliminate the need for a donor. Much progress has been made in direct reprogramming with muscle, blood, the pancreas, and neurons. There are many degrees of direct reprogramming that have been reported. Several progenitor cells, cells that appear committed to their fate, but not fully differentiated, have been shown to be capable of differentiating into a different cell type; this process is called transdetermination. However, in a few cases a fully differentiated cell can actually become a different cell type; this process is called transdifferentiation (Graf and Enver, 2009). (www.allthingsstemcell.com)
GLADSTONE INSTITUTE: The J. David Gladstone Institutes is an independent, nonprofit biomedical research institution affiliated with the University of California, San Francisco (UCSF), devoted to research into cardiovascular disease, viral infections and neurological disorders. Gladstone is composed of three institutes: The Institute of Cardiovascular Disease, which opened in 1979; the Gladstone Institute of Virology and Immunology and the Gladstone Institute of Neurological Disease. While independent, Gladstone is formally affiliated with UCSF. Gladstone investigators participate in many university activities, including the teaching and training of graduate students.