The idea of a miracle cure, bodies healing themselves, holds a certain fascination. Stem cell research brings regenerative medicine a step closer, but there is also controversy. So what are stem cells, and why are they so important? Stem cells are a type of cell that can develop into many other different types of cell. Stem cells can also renew themselves by dividing, even after they have been inactive for a long time.

When a stem cell divides, the new cells may either become a stem cell or a specific cell, such as a blood cell, a brain cell, or a muscle.

A stem cell is known as an "undifferentiated cell," because it can still become any kind of cell. In contrast, a blood cell, for example, is a 'differentiated' cell, because it is already a specific kind of cell.

Stem cells in therapy

In some tissues, stem cells play an important role in regeneration, as they can easily divide, and they can keep replacing dead cells. Scientists believe this may offer potential treatments for conditions such as diabetes and heart disease.

For instance, if someone has damaged tissue in their heart, it might be possible to stimulate the growth of study involved only 11 participants. It is difficult to tell whether the improvement in heart function was caused by the transplantation of stem cells, or whether it was caused by something else.

All of the transplants took place while the patients were undergoing heart bypass surgery, for instance, so it is possible that the improvement in heart function could be due to the bypass rather than the stem cell treatment.

To investigate further, the researchers plan to do another study, this time including a control group of patients with heart failure who undergo bypass surgery, but who do not receive the stem cell treatment.

Another study published in Nature Communications suggested that stem cell therapies could form the basis of personalized diabetes treatment.

In mice and laboratory-grown cultures, the researchers successfully produced insulin-secreting cells from stem cells derived from the skin of people with type 1 diabetes.

Stem cells in drug development

One way that stem cells are used at the moment is in developing and testing new drugs. The type of stem cells commonly used for this purpose are called induced pluripotent stem cells.

These are cells that have already become differentiated, but then they have been genetically reprogrammed using controlled viruses. In this way, they resemble undifferentiated embryonic stem cells.

New differentiated cells can be grown from these pluripotent stem cells to resemble, for instance, cancer cells. Creating these cells means that anti-cancer drugs can be tested using them.

A wide variety of cancer-cell types are already being made using this method. However, because these cells cannot yet be made to mimic cancer cells in a controlled way, the results cannot always be precisely replicated.

Do current therapies work?

In recent years, clinics have opened that provide stem cell treatments. A 2016 study published in Cell Stem Cell counts 570 of these clinics in the United States alone. They offer stem cell-based therapies for disorders ranging from sports injuries to cancer.

However, stem cell therapies are still mostly theoretical rather than evidence-based. Very few stem cell treatments have even reached the earliest phase of a clinical trial. Most of the current research is being carried out in mice or in the petri dish.

Despite this, clinics are allowed by the U.S. Food and Drug Administration (FDA) to inject patients with their own stem cells, as long as the cells are intended to perform only their normal function.

Ethical issues

The use of stem cells in medical research has been controversial, historically. The reason is that when the therapeutic use of stem cells first came to the public's attention in the late 1990s, it was because scientists had first mastered the technique for deriving human stem cells from embryos.

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

For some people, life starts when a baby is born, or when an embryo develops into a fetus. Others believe that human life begins at conception, so an embryo has the same moral status and rights as a human adult or child. It was because of his strong, pro-life religious views that President George W. Bush banned funding for human stem cell research in 2001.

"At its core, this issue forces us to confront fundamental questions about the beginnings of life and the ends of science," Bush announced at the time. "My position on these issues is shaped by deeply held beliefs. I also believe human life is a sacred gift from our creator." However, the research restrictions implemented by the Bush administration were partially rolled back during President Obama's time in office.

Pluripotent stem-cell use was introduced in 2006. The stem cells in this method do not come from embryonic stem cells. As a result, this technique is not associated with the same ethical concerns. With this, and other recent advances in stem cell technology, attitudes toward stem cell research have evolved a little.

Current research

Stem cell research is driving forward the scientific understanding of how an organism develops from a single cell, and how defective cells are replaced by healthy cells in people and animals.

Understanding cancer

Many serious medical conditions that occur in humans, such as cancer and birth defects, are caused by cells dividing abnormally. By studying stem cells and the process of cell differentiation, we may better understand how these diseases arise and how they may be treated.

Regenerative medicine

In June 2016, two researchers took second prize in the materials category of the United Kingdom's Royal Society of Chemistry's emerging technology competition for creating a synthetic biomaterial that stimulates stem cells native to a patient's own teeth.

The researchers believe that this material will replace fillings, as the stem cells would simply prompt the damaged teeth to heal themselves. Although much more research is necessary before stem cell therapies can become part of regular medical practice, the science around stem cells is developing all the time.

In almost every therapy area, there are hopes that stem cell technology will revolutionize therapeutic norms and introduce at least a new standard of personalized treatment, and maybe even self-healing bodies.