New Stem Cell Breakthough Called “Milestone”

If what scientists say they’ve done is true, it could one of the biggest and most promising breakthroughs in recent medical history. After years of facing protests from religious groups over the use of embryos to harvest stem cells, researchers say they’ve found a way to “manufacture” the precious items without using material from the unborn.

The teams had originally accomplished the feat in mice five months ago, but have now confirmed they’ve duplicated the effect in people using ordinary human skin cells.

Stem cells are basically blank building blocks that researchers believe can be turned into almost anything in the body without fear of rejection. They’ve been touted as possible effective treatments for everything from Parkinson’s disease and diabetes to nerve damage. Some advocates, like the late Christopher Reeve, were convinced the cells could help those who are paralyzed walk again by recreating damaged spinal tissue.

But they were stymied in their quest by faith based groups who objected to using fetuses to find the material. This latest development has many calling it one of the most important in modern history. “This work represents a tremendous scientific milestone – the biological equivalent of the Wright Brothers’ first airplane,” enthuses Dr. Robert Lanza, chief science officer of Advanced Cell Technology. “It’s a bit like learning how to turn lead into gold.”

Those behind the findings are stunned at how simple the once-thought impossible technique really is. “People didn’t know it would be this easy,” stem cell pioneer James Thomson explains. “Thousands of labs in the United States can do this, basically tomorrow.”

But like every rose, there’s a thorn – the process involves disrupting the DNA of the skin cells, which creates the potential for developing cancer. And that may negate its use for some of the most serious disabilities it’s hoped to treat. And the research comes with a common caveat –  while promising, the real benefits may still be years away.

Stem Cell Primer

They’re the body’s repair system – able to transform into different types of cells, including blood cells and brain cells, to help in healing.

No wonder then that scientists and health experts are so enthusiastic about the potential of stem cells. But stem cell research is a contentious subject in the United States, with both sides equally passionate about why it should or shouldn’t be pursued.

Here’s a primer on what human embryonic stem cells are and why scientists are excited about their potential, courtesy the U.S. National Institutes of Health:

What are human embryonic stem cells?

Stem cells are cells that have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells for as long as the person or animal is still alive. When a stem cell divides, each “daughter” cell has the potential to either remain a stem cell or become another type of cell with a more specialized function, such as a muscle cell, a red blood cell, or a brain cell.

What classes of stem cells are there?

There are three classes of stem cells: totipotent, multipotent, and pluripotent.

A fertilized egg is considered totipotent, meaning that its potential is total; it gives rise to all the different types of cells in the body.

Stem cells that can give rise to a small number of different cell types are generally called multipotent.

Pluripotent stem cells can give rise to any type of cell in the body except those needed to develop a fetus.

Where do stem cells come from?

Pluripotent stem cells are isolated from human embryos that are a few days old. Cells from these embryos can be used to create pluripotent stem cell “lines” – cell cultures that can be grown indefinitely in the laboratory. Pluripotent stem cell lines have also been developed from fetal tissue obtained from fetal tissue (older than 8 weeks of development).

Why do scientists want to use stem cell lines?

Once a stem cell line is established from a cell in the body, it is essentially immortal, no matter how it was derived. That is, the researcher using the line will not have to go through the rigorous procedure necessary to isolate stem cells again. Once established, a cell line can be grown in the laboratory indefinitely and cells may be frozen for storage or distribution to other researchers.

Stem cell lines grown in the lab provide scientists with the opportunity to “engineer” them for use in transplantation or treatment of diseases. For example, before scientists can use any type of tissue, organ, or cell for transplantation, they must overcome attempts by a patient’s immune system to reject the transplant. In the future, scientists may be able to modify human stem cell lines in the laboratory by using gene therapy or other techniques to overcome this immune rejection. Scientists might also be able to replace damaged genes or add new genes to stem cells in order to give them characteristics that can ultimately treat diseases.

Why are doctors and scientists so excited about human embryonic stem cells?

Stem cells have potential in many different areas of health and medical research. To start with, studying stem cells will help us to understand how they transform into the dazzling array of specialized cells that make us what we are. Some of the most serious medical conditions, such as cancer and birth defects, are due to problems that occur somewhere in this process. A better understanding of normal cell development will allow us to understand and perhaps correct the errors that cause these medical conditions.
Another potential application of stem cells is making cells and tissues for medical therapies. Today, donated organs and tissues are often used to replace those that are diseased or destroyed. Unfortunately, the number of people needing a transplant far exceeds the number of organs available for transplantation. Pluripotent stem cells offer the possibility of a renewable source of replacement cells and tissues to treat a myriad of diseases, conditions, and disabilities including Parkinson’s and Alzheimer’s diseases, spinal cord injury, stroke, burns, heart disease, diabetes, osteoarthritis and rheumatoid arthritis.

Have human embryonic stem cells been used successfully to treat any human diseases yet?

Scientists have only been able to do experiments with human embryonic stem cells (hESC) since 1998, when a group led by Dr. James Thomson at the University of Wisconsin developed a technique to isolate and grow the cells. Moreover, federal funds to support hESC research have only been available since August 9, 2001, when President Bush announced his decision on federal funding for hESC research. Because many academic researchers rely on federal funds to support their laboratories, they are just beginning to learn how to grow and use the cells. Thus, although hESC are thought to offer potential cures and therapies for many devastating diseases, research using them is still in its early stages.

Adult stem cells such as blood-forming stem cells in bone marrow (called hematopoietic stem cells, or HSCs) are currently the only type of stem cell commonly used to treat human diseases. Doctors have been transferring HSCs in bone marrow transplants for over 40 years. More advanced techniques of collecting, or “harvesting”, HSCs are now used in order to treat leukemia, lymphoma and several inherited blood disorders.

The clinical potential of adult stem cells has also been demonstrated in the treatment of other human diseases that include diabetes and advanced kidney cancer. However, these newer uses have involved studies with a very limited number of patients.

What will be the best type of stem cell to use for therapy?

Pluripotent stem cells, while having great therapeutic potential, face formidable technical challenges. First, scientists must learn how to control their development into all the different types of cells in the body. Second, the cells now available for research are likely to be rejected by a patient’s immune system. Another serious consideration is that the idea of using stem cells from human embryos or human fetal tissue troubles many people on ethical grounds.

Until recently, there was little evidence that multipotent adult stem cells could change course and provide the flexibility that researchers need in order to address all the medical diseases and disorders they would like to. New findings in animals, however, suggest that even after a stem cell has begun to specialize, it may be more flexible than previously thought.

There are currently several limitations to using adult stem cells. Although many different kinds of multipotent stem cells have been identified, adult stem cells that could give rise to all cell and tissue types have not yet been found. Adult stem cells are often present in only minute quantities and can therefore be difficult to isolate and purify. There is also evidence that they may not have the same capacity to multiply as embryonic stem cells do. Finally, adult stem cells may contain more DNA abnormalities-caused by sunlight, toxins, and errors in making more DNA copies during the course of a lifetime. These potential weaknesses might limit the usefulness of adult stem cells.

Courtesy U.S. National Institutes of Health

Online video guide: explaining stem cells