The idea of a miracle cure and bodies healing themselves holds a particular fascination. Stem cell research brings regenerative medicine a step closer, but many of the ideas and concepts remain controversial. So what are stem cells, and why are they so important?

Stem cells are a type of cell that can develop into many other types of cell. Stem cells can also renew themselves by dividing, even after they have been inactive for a long time.

The human body requires many different types of cell to function, but it does not produce each cell type fully formed and ready to use. Instead, it produces stem cells that have a wide range of possible functions. However, stem cells need to become a specific cell type to be useful.

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

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 is already a specific kind of cell.

Stem cells in storage
Stem cells may provide the key to regenerative medicine, in which the body heals itself.

In some tissues, stem cells play an essential role in regeneration, as they can divide easily to replace dead cells.

Scientists that knowing how stem cells work may lead to possible treatments for conditions, such as diabetes and heart disease.

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.

Researchers on a small-scale study published in the Journal of Cardiovascular Translational Research tested this method.

The results showed a reduction of the size of scarred heart tissue caused by heart attacks when doctors transplanted stem cells to the damaged area.

Doctors have always considered this kind of scarring permanent and untreatable.

However, this small study involved only 11 participants. This makes it difficult to tell whether the improvement in heart function resulted from the transplantation of stem cells or whether it was due to something else.

For example, all of the transplants took place while the individuals were undergoing heart bypass surgery, so it is possible that the improvement in heart function was due to the bypass rather than the stem cell treatment.

To investigate further, the researchers plan to do another study. This study will include a control group of people with heart failure who undergo bypass surgery but who do not receive the stem cell treatment.

Another investigation, published in in 2016, has 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.

Jeffrey R. Millman, assistant professor of medicine and biomedical engineering at Washington University School of Medicine and first author, :

"In theory, if we could replace the damaged cells in these individuals with new pancreatic beta cells — whose primary function is to store and release insulin to control blood glucose — patients with type 1 diabetes wouldn't need insulin shots anymore."

Jeffrey R. Millman

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

"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," he said.

Stem cells could have vast potential in developing new therapies.

Stem cells in drug development

stem cell research
Scientists are using stem cells to develop and test new drugs.

One way that scientists use stem cells at the moment is in developing and testing new drugs.

The type of stem cells that scientists commonly use for this purpose are called induced pluripotent stem cells.

These are cells that have already undergone differentiation, but which scientists have genetically "reprogrammed" using viruses, so they can divide and become any cell. In this way, they act like undifferentiated stem cells.

Scientists can grow differentiated cells from these pluripotent stem cells to resemble, for instance, cancer cells. Creating these cells means that scientists can use them to test anti-cancer drugs.

Researchers are a wide variety of cancer cells using this method. However, because they cannot yet create cells that mimic cancer cells in a controlled way, it is not always possible to replicate the results precisely.

Scientists stem cells in different ways.

Embryonic stem cells an embryo that is just a few days old.

Scientists can extract adult stem cells from different types of tissue, including the brain, bone marrow, blood vessels, skeletal muscle, skin, teeth, the gut, the liver, among others.

Amniotic fluid contains stem cells. Many women opt for an amniocentesis test that checks for congenital disabilities before the child is born. If the doctor keeps the fluid, they could use it in the future to treat other conditions either during gestation or after birth.

Induced pluripotent stem cells (iPS cells) are cells that scientists can reprogram to act as stem cells, for use in regenerative medicine.

After collecting the stem cells, scientists usually in liquid nitrogen for future use.