Stem cell research has the potential to revolutizonize the practice of medicine and improve the quality and length of life for individuals affected with ALS.
For an overview on stem cells read our Stem Cell Primer
Stem Cell Research Breakthroughs
Two recent stem cell research scientific breakthroughs have opened up the possibility of stem cell therapy:
The identification of human pluripotent stem cells from embryonic and fetal tissue. In 1998, human embryonic stem cells were derived from human blastocysts and similar cells were isolated from germ tissue. These cells were found to be able to divide indefinitely and to form cells of the three major tissue types - endoderm (which forms the lining of the gut, as well as cells of the pancreas and the liver), mesoderm (which produces muscle, bone, and blood), and ectoderm (which gives rise to the 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 that adult stem cells have greater "plasticity" than previously believed - that is, some adult-derived cells appear to be capable of developing into cell types outside of the tissue of origin (e.g. 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.
Potential Benefits
There are several important clinical implications of the breakthroughs described above.
Cell Replacement Therapies
Pluripotent and multipotent stem cells hold great promise for both clinical and research applications. Potentially these stem cells could be stimulated to develop into specialized cells that represent renewable sources of cells and tissue for transplantation. Cell replacement therapy could treat injuries and various genetic and degenerative conditions. The list of diseases that may be amenable to stem cell repair include muscular dystrophies, retinal degeneration, Alzheimer disease, Parkinson's disease, arthritis, diabetes, spinal cord injuries, and blood disorders such as hemophilia.
Understanding Cell Specialization
Studying human pluripotent stem cells can lead to the identification of factors responsible for differentiation of stem cells into specialized cell types. These factors may ultimately be used to drive tissue regeneration and repair if administered therapeutically. In addition to providing information on cell determination and differentiation, valuable basic biological information relating to human development, genomic imprinting and somatic cell aging can be derived from the study of human pluripotent stem cells.
Changing the way we develop and test drugs for safety
Researchers could study the beneficial and toxic effects of new medications on human pluripotent stem cells that have been developed to mimic the disease processes. Only drugs that are both safe and appear to have a beneficial effect in cell line testing would graduate to further testing in laboratory animals and human subjects.
The Source of Stem Cells for Stem Cell Research
There are a number of different sources for stem cells, ranging from embryonic, fetal, placental and cord blood to adult tissues. Research being undertaken by members of the Stem Cell Network will help in understanding the differences between stem cell types and assist in identifying those that offer the most potential for development of therapies.
Our present knowledge and understanding suggests that the advantages of using human embryonic stem cells are that:
- they are easy to identify in the 4-5 day embryonic sac, and can be removed in essentially pure form;
- they are relatively easy to grow in culture; and,
- they have a well documented capacity to form any cell type.
In contrast current evidence suggests adult stem cells may have more limited potential because they:
- have not been shown to be capable of developing into all of the different cell and tissue types of the body;
- are difficult to obtain, since they are often present in only small quantities;
- difficult to isolate, purify and maintain in the undifferentiated state;
- appear to decrease in numbers as a person ages;
- have a possibility of accumulated mutations and more DNA changes
However, in the long run, adult stem cells may still prove the best choice for cell therapy. If they can be harvested from a patient, grown and amplified sufficiently to be used to repair disease or damaged cells or tissues, they would offer the following advantages:
- There would be no problem with immune rejection;
- Adult stem cells may be less prone to promoting tumors;
- A ready supply of stem cells in adult tissue
Click here to download English Stem Cell Fact Sheet
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For More Information: read our stem cell page.
