Stem cells

Stem cells are cells that can both replicate themselves and differentiate into other types of cells. In a developing embryo, pluripotent stem cells, which can differentiate into all cell types, are told through complex signaling to differentiate into other cells. Embryonic stem cells go through several stages before becoming functional neurons, cardiomyocytes (beating heart cells), pancreatic beta cells or other types of tissue.

Once an embryonic stem cell starts to differentiate, it becomes multipotent and can become many cell types. These cells are moving towards a cellular identity but still have the flexibility to become different types of tissue. In other words, the cell knows its address and will migrate to the heart, liver, brain or other part of the body and differentiate into more specific cells types. Certain tissues in adults have their own multipotent stem cells, often called somatic stem cells or “adult stem cells.” However, the latter term is somewhat misleading as these cells are also found in embryos and children.

Perhaps the most intriguing types of stem cells are induced pluripotent stem (iPS) cells. These cells are created from fully differentiated cells, often skin cells, which have been reprogrammed to become pluripotent stem cells. Like their embryonic cousins, iPS cells can form all cell types. This approach offers a number of benefits. For one, iPS cells may be ideal for transplantation, as they could be taken from a patient and would not face rejection from the patient’s immune system. Also, iPS cells could be used to study diseases on a cellular level.

“These iPS cells will give us the ability to study the molecular underpinnings of disease,” says Dr. Stuart Lipton, director of the Del E. Webb Neuroscience, Aging and Stem Cell Research Center. “We can set up models for Parkinson’s and figure out what is going wrong with those cells.”

Currently, iPS cells have their drawbacks. Some of the methods used to create them make them unsuitable for clinical use. And they replicate slowly, making them difficult to study. Also, scientists don’t know if iPS cells are identical to embryonic stem cells. More study is needed, but breakthroughs are being announced with great frequency This is Neural Stem Cells.

“The technology for iPS cells is changing every day,” says Dr. Lipton. “They have great potential, but we need to learn whether they are identical to embryonic stem cells, and we just don’t know yet.”