Researchers have been looking for something that can help the body heal itself. Although studies are ongoing, stem cell research brings this notion of regenerative medicine a step closer. However, many of its 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 types of cells. For example, they can become muscle or brain cells. They can also renew themselves by dividing, even after they have been inactive for a long time.

Stem cell research is helping scientists understand how an organism develops from a single cell and how healthy cells could be useful in replacing cells that are not working correctly in people and animals.

Researchers are now studying stem cells to see if they could help treat a variety of conditions that impact different body systems and parts.

This article looks at types of stem cells, their potential uses, and some ethical concerns about their use.

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The human body requires many different types of cells to function, but it does not produce every cell type fully formed and ready to 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 kind of cell.

The sections below look at 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. They do this by taking the cells from the embryos at the blastocyst stage, which is the phase in development before the embryo implants in the uterus.

These cells are undifferentiated cells that divide and replicate. However, they are also able to differentiate into specific types of cells.

Adult stem cells

There are two main types of adult stem cells: those in developed bodily tissues and induced pluripotent stem (iPS) cells.

Developed bodily tissues — such as organs, muscles, skin, and bone — include some stem cells. These cells can typically become differentiated cells based on where they exist. 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 collecting the stem cells, scientists usually store them in liquid nitrogen for future use. However, researchers have not yet been able to turn these cells into any kind of bodily cell.

Scientists are researching how to use stem cells to regenerate or treat the human body.

The list of conditions that stem cell therapy could help treat may be endless. Among other things, it could include conditions such as Alzheimer’s disease, heart disease, diabetes, and rheumatoid arthritis. Doctors may also be able to use stem cells to treat injuries in the spinal cord or other parts of the body.

They may do this in several ways, including the following.

Using stem cells in therapy

In some tissues, stem cells play an essential role in regeneration, as they can divide easily to replace dead cells. Scientists believe that knowing how stem cells work can help treat damaged tissue.

For instance, if someone’s heart contains damaged tissue, doctors might be able to stimulate healthy tissue to grow by transplanting laboratory-grown stem cells into the person’s heart. This could cause the heart tissue to renew itself.

One study suggested that people with heart failure showed some improvement 2 years after a single-dose administration of stem cell therapy. However, the effect of stem cell therapy on the heart is still not fully clear, and research is still ongoing.

Another investigation suggested that stem cell therapies could be the basis of personalized diabetes treatment. In mice and laboratory-grown cultures, researchers successfully produced 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 the Washington University School of Medicine in St. Louis, MO — said, “What we’re envisioning is an outpatient procedure in which some sort of device filled with the cells would be placed just beneath the skin.”

Millman hopes that these stem cell-derived beta cells could be ready for research in humans within 3–5 years.

Stem cells could also have vast potential in developing other new therapies.

Using stem cells in drug development

Another way that scientists could use stem cells is in developing and testing new drugs.

The type of stem cell that scientists commonly use for this purpose is the iPS cell. These are cells that have already undergone differentiation but which scientists have genetically “reprogrammed” using genetic manipulation, sometimes using viruses.

In theory, this allows iPS cells to divide and become any cell. In this way, they could act like undifferentiated stem cells.

For example, scientists want to grow differentiated cells from iPS cells to resemble cancer cells and use them to test anticancer drugs. This could be possible because conditions such as cancer, as well as some congenital disabilities, happen because cells divide abnormally.

However, more research is taking place to determine whether or not scientists really can turn iPS cells into any kind of differentiated cell and how they can use this process to help treat these conditions.

In recent years, clinics have opened that offer different types of stem cell treatments. One 2016 study counted 570 of these clinics in the United States alone. They appear to offer stem cell-based therapies for conditions ranging from sports injuries to cancer.

However, most stem cell therapies are still theoretical rather than evidence-based. For example, researchers are studying how to use stem cells from amniotic fluid — which experts can save after an amniocentesis test — to treat various conditions.

The Food and Drug Administration (FDA) does allow clinics to inject people with their own stem cells as long as the cells are intended to perform only their normal function.

Aside from that, however, the FDA has only approved the use of blood-forming stem cells known as hematopoietic progenitor cells. Doctors derive these from umbilical cord blood and use them to treat conditions that affect the production of blood. Currently, for example, a doctor can preserve blood from an umbilical cord after a baby’s birth to save for this purpose in the future.

The FDA lists specific approved stem cell products, such as cord blood, and the medical facilities that use them on its website. It also warns people to be wary of undergoing any unproven treatments because very few stem cell treatments have actually reached the earliest phase of a clinical trial.

Historically, the use of stem cells in medical research has been controversial. This is because when the therapeutic use of stem cells first came to the public’s attention in the late 1990s, scientists were only deriving human stem cells from embryos.

Many people disagree with using human embryonic cells for medical research because extracting them means destroying the embryo. This creates complex issues, as people have different beliefs about what constitutes the start of human life.

For some people, life starts when a baby is born, while for others, it starts when an 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 had strong antiabortion views. He believed that an embryo should be considered a life and not be used for scientific experiments. Bush banned government funding for human stem cell research in 2001, but former U.S. president Barack Obama then revoked this order. Former U.S. president Donald Trump and current U.S. president Joe Biden have also gone back and forth with legislation on this.

However, by 2006, researchers had already started using iPS cells. Scientists do not derive these stem cells from embryonic stem cells. As a result, this technique does not have the same ethical concerns. With this and other recent advances in stem cell technology, attitudes toward stem cell research are slowly beginning to change.

However, other concerns related to using iPS cells still exist. This includes ensuring that donors of biological material give proper consent to have iPS cells extracted and carefully designing any clinical studies.

Researchers also have some concerns that manipulating these cells as part of stem cell therapy could lead to the growth of cancerous tumors.

Although scientists need to do much more research before stem cell therapies can become part of regular medical practice, the science around stem cells is developing all the time.

Scientists still conduct embryonic stem cell research, but research into iPS cells could help reduce some of the ethical concerns around regenerative medicine. This could lead to much more personalized treatment for many conditions and the ability to regenerate parts of the human body.

Learn more about stem cells, where they come from, and their possible uses here.