Stem Cells: The Basics .......

Stem cells are packed with possibility. Embryonic or "pluripotent" stem cells have superpowers: They can give rise to various organs or tissue cells, or instead divide and renew themselves. Meanwhile, adult stem cells await throughout your body to replenish worn-out or damaged cells.

Researchers are finding ways to guide embryonic stem cells to generate new cells for potential treatments. Stem cells likely have a role to play in personalized or precision medicine.

Currently, stem cells are being deployed in early studies to restore vision in people with eye diseases such as cataracts and age-related macular degeneration. Special stem cell lines allow new drugs to be tested for cancer-fighting ability.

However, some treatments offered in stem cell clinics cropping up throughout the country aren't ready for prime time, health officials say, and they come with potential risks.

In the future, conditions such as diabetes, traumatic spinal cord injury, heart disease, hearing loss and Duchenne muscular dystrophy might be treated by transplanting cells generated from human stem cells, according to the National Institutes of Health.

However, there's much more to be learned about basic stem cell biology and viable health care applications. Carefully controlled clinical trials are needed to determine the safety, effectiveness and long-term results of any type of stem cell therapy.

Even so, certain stem cell clinics are hyping unproven, unregulated treatments for all sorts of medical conditions without any evidence that they work. Stories of disillusioned patients wasting thousands of dollars on useless treatments are emerging. The Food and Drug Administration in November issued a general caution detailing its concerns over "treatments that are illegal and potentially harmful."

Here's what you should know about the still-budding science of stem cells.

What is a stem cell?

Unlike other cells, stem cells are unspecialized or "undifferentiated." They have the unique ability to divide or differentiate into many types of cells with specific functions – such as muscle, skin or bone cells. Stem cells can also give rise to new generations of undifferentiated stem cells, thus renewing themselves.

What are the main types of stem cells?

Pluripotent stem cells come from early embryos. In the 3-to-5-day-old embryo, these versatile cells give rise to specialized tissues and organs throughout the body: heart, lungs, skin, eggs, sperm and more.

"Pluripotent stem cells are interesting, because they can become anything," says William Lowry, a professor of molecular, cell and developmental biology at the Broad Center of Regenerative Medicine & Stem Cell Research at the University of California–Los Angeles. "And because of that, they need to be well-controlled." One challenge for researchers is balancing the regenerative abilities of stem cells with their ability to produce harmful growths, like tumors.

Adult stem cells exist in small quantities in many adult tissues such as the brain and spinal cord, digestive tract, skin layers and other parts of the body. Adult stem cells, also called "somatic" stem cells, act as an internal repair system.

"We all have stem cells in most of our organs that are responsible for maintaining the organs in the event of normal cell turnover," Lowry says. For example, he says, skin and intestinal cells turn themselves over every week or two. Others respond on an as-needed basis. "Even in your brain, you probably have some stem cells that don't do much unless there's an injury," he adds.

Adult stem cells have limits to their versatility. "A lot of people are selling the idea that you can take cells from fat and suck them out, expand them in culture and inject them back into a person," Lowry says. "And people say that you can basically treat anything with them – which is not true. Those cells from fat should be able to make fat and probably not much else, according to all the biology we know."

What kinds of stem cells are used in research?

Human embryonic stem cells. Most are derived from eggs fertilized in vitro in an IVF clinic and then donated for research. They are not derived from eggs fertilized in a woman's body, as pointed out in patient information from the National Institutes of Health.

Induced pluripotent stem cells. These adult cells have been genetically reprogrammed to act like embryonic stem cells. "Although additional research is needed, human induced pluripotent stem cells are already useful tools for drug development and modeling of diseases," according to the NIH.

Umbilical cord stem cells. These cells are collected from the umbilical cord at birth. Cord stem cells can produce all of the red blood cells in the body. At present, cord blood transplants are primarily used to treat patients who've had their bone marrow destroyed by high-dose chemotherapy. Some parents choose cord blood banking to store their baby's cord blood in case it's needed for future use.

What are some proven stem cell treatments?

Bone marrow transplants are the "gold standard" of stem cell therapy, Lowry says. They're also known as hematopoietic stem cell transplants, which refers to blood cell production. "It's a very effective way of replacing, essentially, your entire blood system," he says.

Skin grafting for severe burns is another established stem cell treatment. The patient's own epidermal cells, or skin cells, are taken to be reproduced in the lab and then used to replace damaged skin.

 

 

Which evolving stem cell treatments show promise?

Although cataracts usually affect older adults, in some cases infants are born with them. In 2016, researchers treated 12 infants who had cataracts by removing the damaged lens from their eyes while leaving behind their own natural stems cells to regenerate a new lens.

An experimental form of stem cell transplant was recently used for adults with advanced age-related macular degeneration, a vision condition that can cause blindness. In the pilot study published in the April 4 issue of Science Translational Medicine, stem cells engineered in the lab were implanted behind the eye's retina to replace damaged cells. The tiny, early study was done to demonstrate that implants were safe and well-tolerated by patients. Future studies will be needed to evaluate their effectiveness.

A form of gene therapy has been combined with stem cell transplant to cure the rare childhood condition known as "Bubble Boy" disease, or severe combined immunodeficiency. Recently, grafts from genetically modified stem cells have been used experimentally to treat a rare blistering disease called epidermolysis bullosa.

In his own work, Lowry is using human pluripotent stem cells to model how the developmental process can malfunction, as in autism spectrum disorders with respect to brain cells.

How can stem cell research move forward?

A nonprofit research group is launching new tools that may deepen scientific understanding of the complex properties of stem cells.

"If you start to differentiate stem cells, or if you inject stem cells into animals, you don't know what the fates of those stem cells are until after your experiment is done," says Rick Horwitz, executive director of the Allen Institute for Cell Science, established by Microsoft co-founder Paul Allen in 2014. "So, you really don't know what you have. Obviously, if stems cells repair a damaged heart, for example, you have an answer. But how well did it work? And did all the cells participate?"

In early May, the institute launched what it calls the first predictive and comprehensive 3D model of a live human stem cell. "Whatever a cell does is coupled with how the cell is organized," Horwitz says. Machine learning tools, freely available, can help scientists visualize a stem cell's characteristic infrastructure, he says. The institute's specifically created and genetically edited cell lines are the key to their model. These cell lines allow researchers to directly view individual structures that reveal cell function, he explains.

Why should you approach stem cell clinics with extreme caution?

Troubling reports of serious side effects caused by treatments at stem cell clinics should make health consumers think long and hard before offering themselves as patients.

On May 9 of this year, the FDA sought court injunctions against two stem cell clinics, based in Florida and California, to stop them from marketing stem cell products without FDA approval. Manufacturing practices used by these companies included some that could affect products' sterility and put patients at risk, according to an FDA statement.

Previously, in 2017, the FDA took action against another California clinic that combined live vaccines with cellular products derived from body fat to create an unauthorized product given to vulnerable cancer patients. Unproven, experimental treatments were also used on patients with conditions including stroke, multiple sclerosis and chronic obstructive pulmonary disease, according to the agency's statement.

 

 

The International Society for Stem Cell Research suggests asking these questions if you're considering any type of stem cell treatment.

 

 

 

Source: Us News & World Report


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