Researchers have long been searching for something that can help the body heal itself. Although research is ongoing, the study of stem cells takes the concept of regenerative medicine one step closer. However, many ideas and concepts remain controversial. So, what are stem cells and why are they so important?
Stem cells are cells that can develop into other cell types. For example, they can become muscle or brain cells. They can also renew themselves by dividing even after they have been dormant for a long time.
Stem cell research is helping scientists understand how an organism develops from a single cell and how healthy cells can be useful in replacing cells that do not work properly in humans and animals.
Researchers are now studying stem cells to see if they can help treat various diseases affecting different systems and parts of the body.
This article discusses the types of stem cells, their potential uses, and some of the ethical problems associated with their use.
Types
The human body requires many different types of cells to function, but it does not produce all types of cells fully formed and ready for use.
Scientists call a stem cell an “undifferentiated” cell because it can become any cell. In contrast, a blood cell, for example, is a “differentiated” cell because it has already formed into a specific cell type.
The following sections discuss some types of stem cells in more detail.
Embryonic stem cells
Scientists extract embryonic stem cells from unused embryos left over from in vitro fertilization procedures. To do this, they take cells from embryos at the blastocyst stage, which is the stage of development that precedes the embryo’s implantation in the uterus.
These cells are undifferentiated cells that divide and reproduce. However, they are also capable of differentiating into certain cell types.
Adult stem cells
There are two main types of adult stem cells: cells from developed body tissues and induced pluripotent stem cells (iPS).
Developed body tissues – such as organs, muscles, skin and bones – include some stem cells. These cells can usually turn into differentiated cells depending on where they are located. For example, a brain stem cell can only become a brain cell.
On the other hand, scientists manipulate iPS cells to make them behave more like embryonic stem cells for use in regenerative medicine. After harvesting the stem cells, scientists usually store themTrusted source in liquid nitrogen for future use. However, researchers have not yet been able to turn these cells into any type of bodily cell.
Using
Scientists are exploring ways to use stem cells to regenerate or treat the human body.
The list of diseases that stem cell therapy can help treat could be endless. These could include conditions such as Alzheimer’s disease, heart disease, diabetes and rheumatoid arthritis, among others. Doctors can also use stem cells to treat injuries to the spinal cord or other parts of the body.
They can do this in several ways, including the following.
Using stem cells in therapy
In some tissues, stem cells play an important role in regeneration because they can easily divide, replacing dead cells. Scientists believe that knowing how stem cells work can help treat damaged tissue.
For example, if a person’s heart contains damaged tissue, doctors can stimulate the growth of healthy tissue by transplanting lab-grown stem cells into the person’s heart. This could lead to self-renewal of heart tissue.
One study by Trusted Source showed that people with heart failure showed some improvement after 2 years after a single dose of stem cell therapy. However, the effects of stem cell therapy on the heart are not yet completely clear, and research is ongoing.
Another study suggested that stem cell therapy could form the basis of a personalized treatment for diabetes. In mice and in laboratory cultures, the researchers successfully grew insulin-secreting cells from stem cells derived from the skin of people with type 1 diabetes.
Study author Jeffrey R. Millman, an assistant professor of medicine and biomedical engineering at Washington University School of Medicine in St. Louis, said: “We envision an outpatient procedure in which some sort of device filled with cells is placed under the skin.”
Millman hopes that these stem cell-derived beta cells could be ready for human studies within three to five years.
Stem cells could also have great potential for the development of other new therapies.
Using stem cells in drug development
Another use of stem cells by scientists is in the development and testing of new drugs.
The type of stem cells that scientists usually use for this purpose are iPS cells. These are cells that have already differentiated, but which scientists have genetically “reprogrammed” through genetic manipulation, sometimes using viruses.
In theory, this allows iPS cells to divide and transform into any cell. Thus, they can act as undifferentiated stem cells.
For example, scientists want to grow differentiated cancer-like cells from iPS cells and use them to test anti-cancer drugs. This could be possible because diseases such as cancer, as well as some congenital abnormalities, arise because the cells divide abnormally.
However, more research is underway to determine whether scientists can actually turn iPS cells into any kind of differentiated cells and how they can use this process to treat such diseases.
Do current stem cell therapies work?
In recent years, clinics have opened offering various types of stem cell treatments. One 2016 study counted 570 such clinics in the U.S. alone. As it turns out, they offer stem cell treatments for a wide variety of conditions, from sports injuries to cancer.
Still, most stem cell treatments are still theoretical rather than evidence-based. For example, researchers are studying how to use stem cells from amniotic fluid – which specialists can save after amniocentesis – to treat various diseases.
The Food and Drug Administration (FDA) allows clinics to inject people with their own stem cells as long as the cells are for their normal function only.
Beyond that, however, FDATrusted Source has approved the use of only blood-forming stem cells known as hematopoietic progenitor cells. Physicians obtain them from umbilical cord blood and use them to treat diseases affecting blood production. Currently, for example, a physician can save blood from the umbilical cord after the baby is born to save it for this purpose in the future.
The FDA, on its website, lists specific approved stem cell products, such as cord blood, and the medical facilities that use them. The FDA also warns people to be wary of any untested treatments, since very few stem cell therapies have reached the earliest stage of clinical trials.
Ethical issues
Historically, the use of stem cells in medical research has been controversial. This is because when the therapeutic use of stem cells first became known in the late 1990s, scientists obtained human stem cells only from embryos.
Many people disagree with the use of human embryonic cells for medical research because extracting them means destroying the embryo. This creates complex issues because people have different beliefs about what constitutes the beginning of human life.
For some people, life begins when a child is born; for others, it begins when the embryo develops into a fetus. Meanwhile, other people believe that human life begins at conception, so an embryo has the same moral status and rights as a human child.
Former U.S. President George W. Bush held strong views against abortion. He believed that an embryo should be considered life and not used for scientific experimentation. In 2001, Bush banned government funding for human stem cell research, but former U.S. President Barack Obama later rescinded that order. Former U.S. President Donald Trump and current U.S. President Joe Biden also repeatedly legislated on the issue.
By 2006, however, researchers had already begun using iPS cells. Scientists do not derive these stem cells from embryonic stem cells. As a result, this technique does not cause the same ethical problems. Thanks to this and other recent advances in stem cell technology, attitudes toward stem cell research are slowly beginning to change.
However, other problems associated with the use of iPS cells still exist. These include ensuring proper consent of donors of biological material for the extraction of iPS cells and careful design of any clinical trials.
Researchers are also concerned that manipulation of these cells as part of stem cell therapy could lead to the growth of cancerous tumors.
Summary
Although scientists have much more research to do before stem cell therapy becomes part of regular medical practice, the science of stem cells is constantly evolving.
Scientists are still doing research on embryonic stem cells, but iPS cell research may help reduce some of the ethical problems associated with regenerative medicine. This could lead to much more personalized treatments for many diseases and the ability to regenerate parts of the human body.
