Stem Cells

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Embryonic Stem Cells (ES) - Cells taken from unused human embryos at IVF (in-vitro fertilization clinics) that can become any type of cell. However, using these cells destroys the human embryo.


Induced Pluripotent Stem Cells (iPS) - Cells taken from the skin that are reverted back into embryonic cells by switching certain genes on and off (there are 4 out of 20,000 that can help reprogram cells). These cells are implanted in a virus and sent back into the body. This treatment may carry a high risk of cancer.


Adult/Somatic Stem Cells - Undifferentiated cells taken from certains areas of the body that can be manipulated to become differentiated like surrounding tissue. There is thought to be specific areas of tissues and organs that are "stem cell niches," rich in this type of stem cell. There is a phenomenon called transdifferentiation, in which these stem cells can create cells that perform a different function than what is expected.

http://stemcells.nih.gov/

How do scientists get stem cells to specialize in a lab?


Scientists remove the outer layer of a blastocyst and put the inner layer in a petri dish. Only a few survive, but the ones that do can create colonies. These colonies go through self-renewal: they are immortal and can continue to grow indefinitely. At some point, these cells differentiate: they begin to become ectoderm/mesoderm/endoderm cells. To control this differentiation, we add growth factors (Retinoic Acid, Sonic hedgehog and Activin are a few examples) to give the cells specific functions. By simulating the environment of a cell, we can induce it into becoming a certain type.


What are some uses of stem cells in curing diseases?


Stem cells are useful in a variety of circumstances. One of the most well-known areas of stem cell research is hematopoietic cells, which create blood and immune cells. Sickle Cell Anemia is a disease where red blood cells are sickle-shaped, instead of donut shaped, so they are less efficient in delivering oxygen to the body. This results in excruciating pain. Stem cells can replace the genetically-fault hematopoietic cells to create properly-shaped RBC. Neurodgenerative diseases, like Parkinson's, can also be improved by replacing dead neurons. And if we can get stem cells to become beta cells that produce insulin, we can finally find a cure for diabetes. The possibilities for cures are virtually endless, although stem cells are not necessarily the final solution for all diseases.
 The types of cells that scientists can manufacture are:

Hematopoietic stem cells create blood cells: red blood cells, B lymphocytes, T lymphocytes, natural killer cells, neutrophils, basophils, eosinophils, monocytes, and macrophages.

 Mesenchymal stem cells create: bone cells (osteocytes), cartilage cells (chondrocytes), fat cells (adipocytes), and connective tissue cells.

Neural stem cells create: nerve cells (neurons) and two categories of non-neuronal cells—astrocytes and oligodendrocytes.

Epithelial stem cells in the lining of the digestive tract create: absorptive cells, goblet cells, paneth cells, and enteroendocrine cells.

Skin stem cells are located in the basal layer of the epidermis and at the base of hair follicles. The epidermal stem cells create keratinocytes, which leads to the formation of a protective layer in the epidermis. The follicular stem cells can help create both the hair follicle and the epidermis.