How can stem cells advance medicine?. Nat Rep Stem Cells Download citation. Published : 14 June Anyone you share the following link with will be able to read this content:. Sorry, a shareable link is not currently available for this article.
Provided by the Springer Nature SharedIt content-sharing initiative. Advanced search. Skip to main content Thank you for visiting nature. How can stem cells advance medicine? Download PDF. Embryonic stem cells come from human embryos that are three to five days old. They are harvested during a process called in-vitro fertilization. This involves fertilizing an embryo in a laboratory instead of inside the female body.
Embryonic stem cells are known as pluripotent stem cells. These cells can give rise to virtually any other type of cell in the body. Adult stem cells have a misleading name, because they are also found in infants and children. These stem cells come from developed organs and tissues in the body. For example, hematopoietic stem cells are a type of adult stem cell found in bone marrow. They make new red blood cells, white blood cells, and other types of blood cells.
Doctors have been performing stem cell transplants, also known as bone marrow transplants, for decades using hematopoietic stem cells in order to treat certain types of cancer. Scientists have recently discovered how to turn adult stem cells into pluripotent stem cells. These new types of cells are called induced pluripotent stem cells iPSCs. They can differentiate into all types of specialized cells in the body. This means they can potentially produce new cells for any organ or tissue.
To create iPSCs, scientists genetically reprogram the adult stem cells so they behave like embryonic stem cells. This may make them more useful in understanding how diseases develop.
This will help prevent the immune system from rejecting an organ transplant. Research is underway to find ways to produce iPSCs safely. Cord blood stem cells are harvested from the umbilical cord after childbirth. They can be frozen in cell banks for use in the future.
These cells have been successfully used to treat children with blood cancers, such as leukemia, and certain genetic blood disorders. Stem cells have also been found in amniotic fluid. They are donated to science. These embryonic stem cells are pluripotent.
This means that they can turn into more than one type of cell. Adult stem cells. There are 2 types of adult stem cells. One type comes from fully developed tissues such as the brain, skin, and bone marrow. There are only small numbers of stem cells in these tissues. They are more likely to generate only certain types of cells. For example, a stem cell that comes from the liver will only make more liver cells.
The second type is induced pluripotent stem cells. These are adult stem cells that have been changed in a lab to be more like embryonic stem cells. In addition, the technique can cause mutations that predispose cells to cancer.
As a result, some scientists are concerned that the reprogrammed cells will never be suitable for use in patients. For the foreseeable future, stem cell researchers agree that research should continue along all avenues, using embryonic stem cells, adult stem cells, and reprogrammed cells. Myth Adult stem cells have been proven effective in treating more than 70 diseases.
Fact While adult stem cell research holds much promise, blood stem cells offer the only proven adult stem cells therapies. The claim that adult stem cells have been used to cure more than 70 diseases has been widely discredited.
Myth Stem cells from amniotic fluid and umbilical cord blood can be used instead of embryonic stem cells. Fact Amniotic fluid and umbilical cord blood contain adult stem cells. They hold promise for therapy but do not have the properties or potential of embryonic stem cells. Myth The stem cell lines approved by the federal government provide an adequate source of embryonic stem cells for research.
Fact The approved stem cell lines were created on or before Aug. Scientists later determined that those lines are contaminated with animal proteins.
In addition, none of the approved lines was created to model human disease. Although President Bush initially intended to make more than 70 federally approved lines available to scientists, most of these lines turned out to be inadequately characterized, and only 16 such lines remain. Furthermore, many of these lines come from a single clinic in Israel, thus they do not mirror the ethnic and racial diversity in American society.
Fact Some religious people are in opposition. Others believe that embryonic stem cell research is pro-life and that it is immoral not to pursue this research, because of its potential to reduce human suffering. Most religious traditions, including Judaism, Hinduism, Islam, Buddhism, and some branches of Christianity do not consider embryonic stem cell research to be immoral.
Myth Embryonic stem cell research uses embryos that have begun to develop as babies. Fact Stem cells are derived from blastocysts that have only developed for about five days after fertilization. These early stage embryos consist of about cells and are the size of the period at the end of this sentence.
At this stage, the cells are undifferentiated: They have no nervous system, no heart, no limbs and no specialized human tissues. Fact There is no connection between abortion and human embryonic stem cells. By the time a human embryo has implanted in the uterus, its cells have specialized to the point where they can no longer be used for the derivation of embryonic stem cell lines.
The embryos used to derive stem cells are created in dishes in fertility clinics. They are never transferred into the human body and are donated for medical research only when parents decide they are no longer needed for fertility treatment.
Myth Embryos discarded by fertility clinics could be donated to another family rather than discarded or used for research. Fact Snowflake Children is a term used to describe some babies born from leftover IVF clinic embryos donated to other infertility patients.
But the Snowflakes Frozen Embryo Adoption Program claims fewer than births since it began in Meanwhile, thousands of leftover embryos are discarded each year and more than , embryos are currently frozen in fertility clinics; most will eventually be discarded. Many embryos created for IVF are discarded because they do not develop normally or are known to carry serious genetic abnormalities. Such embryos are not suitable for implantation.
But in the laboratory, these defective embryos could help researchers understand genetically linked diseases and develop treatments for them.
Myth Stem cell research is unregulated and unrestricted, thus paving the way for scientists to go down a dangerous path. There are additional restrictions being introduced in a Michigan ballot proposal. For example, under this ballot proposal, embryos could not be bought or sold, could only be generated for the purpose of fertility treatment, and then could only be used for stem cell research if they could no longer be used for fertility treatment and were donated with the informed consent of the donor.
This microscope image x magnification shows an oval cluster of roughly 1, human embryonic stem cells growing together as a colony. Image courtesy of Gary Smith.
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