Recent breakthroughs in stem cell research have revolutionized the practice of regenerative medicine - offering hope for patients with life threatening diseases. The two major milestones that opened up the possibility of stem cell therapy are:
Identification of human pluripotent stem cells from embryonic and fetal tissue in 1998.
When human embryonic stem cells were derived from human blastocysts and similar cells were isolated from germ tissue, these stem cells were found to be able to divide indefinitely and form cells of the three major tissue types:
- Endoderm - Cells that form the lining of the gut, as well as cells of the pancreas and the liver.
- Mesoderm - Cells that produce muscle, bone and blood.
- Ectoderm - Cells that give rise to epidermal tissues and the nervous system.
The ability of these cells to form the three major tissue types indicates that the cells are pluripotent.
The possibility of adult stem cells having greater 'plasticity'.
Adult stem cells are capable of developing into cell types outside the tissue of origin. For example, human blood stem cells have been shown to differentiate into liver cells. However, while scientists now believe that some adult stem cells from one tissue can develop into cells of another tissue, no adult stem cell has been definitively shown to be completely pluripotent.