What is a stem cell?
It is really simple. A stem cell is a cell that can do two things: (1) make more of itself or self renew and (2) become different kinds of cells or "differentiate." We all have stem cells in every organ and tissue in our body. Stem cell therapies aim to harness the power of different stem cells to fight disease, restore normal function, repair injuries, replace lost cells, and regenerate failing organs. The term "stem cell" on its own is often debated as there are different types and sources of stem cells. There are adult stem cells, embryonic stem cells, cancer stem cells, and reprogrammed iPS ("induced pluripotent stem cells"), each with very different potential to treat disease. (For more detail, see keywords and definitions below.)
What is regenerative medicine?
Regenerative medicine is a new field that brings together experts in biology, chemistry, computer science, engineering, genetics, medicine, robotics, and other fields to find solutions to some of the most challenging medical problems faced by humankind. At its simplest level, regenerative medicine is the use of novel cell, gene, and molecular tools to repair the underlying injury to an organ or tissue rather than simply treating the symptom. In other words, the goal of regenerative medicine is repair of injury or "regeneration" of healthy tissue. Regenerative medicine is rapidly showing promise for treating injuries and diseases with tissues specifically grown for a purpose, combining cells (including stem cells) with materials created in a lab. Combinations of materials and cells could be the key to treating many diseases and injuries. If we can enhance the body's own natural healing process with new tissues, they hold the potential for taking over the function of a permanently damaged organ.
What is cell therapy?
Cell therapy essentially involves treating disease with your own cells ("autologous") or in some cases someone else's ("allogeneic"). The earliest cell therapy was bone marrow transplant back in the 1960s. Cell therapy has a long and safe history. Today cell therapy often means the use of bone marrow, blood, skin, fat or other stem cells for regenerative medicine.
Dr. Taylor answers a few questions specifically about her work:
How did you grow a new heart?
Working with my research team, we built the first beating bioartificial heart using a tissue scaffold from a rat heart and heart cells from newborn rats.
What has happened since?
We're testing the approach with other organs. We're also working to make the bioartificial heart better and stronger and keeping it alive longer.
What is the eventual goal?
The goal of these studies is to create replacements for human blood vessels, hearts, and other organs using a donor human or pig scaffold and the recipient's own cells.
What needs to happen before this treatment becomes widely available?
Researchers must refine the heart to be strong enough to actually pump blood through the body. We need to test manufactured organs in animal studies and eventually in human clinical trials. And we need to receive FDA approval.
Why not just rely on conventional heart transplants?
The supply of donor organs for transplant falls far short of the number needed. Each year, tens of thousands of individuals in the United States alone die while waiting for a suitable organ. In addition, recipients of conventional organ transplants must take immune-system-compromising medication for the rest of their lives to prevent their bodies from rejecting the new organ. They are essentially trading one disease for another. In the case of a heart, because the replacement heart would be made up of the recipient's own cells and the body might replace the scaffold with its own cells, a recipient of a bioartificial heart conceivably could get by without anti-rejection medicine.
When will this lead to replacement hearts?
We expect that it will be at least 10 years before bioartificial hearts will be available for clinical studies. Before then we predict cardiac valves, blood vessels, patches, and other simpler tissues will be used clinically. In fact, already bladders and trachea have been implanted in patients. In fact, as recently as this year, this technology was used to generate a windpipe (trachea) scaffold that was reseeded with autologous cells and transplanted into a young woman in Europe and the US: First U.S. Patient Gets Stem Cell Trachea Transplant.
Would this work with other organs?
Regenerative medicine research opens the door to exploring the construction of other replacement organs such as kidney, pancreas, lung, and liver.
Keywords (Index Terms)
Adult stem cell
Bone marrow stromal cells
Bone marrow stromal stem cells (skeletal stem cell)
Cord blood stem cells
Embryonic stem cells
Embryonic stem cell line
Hematopoietic stem cell
Human embryonic stem cell (hESC)
Induced pluripotent stem cell (iPSC)
|Mesenchymal stem cells |
Mesenchymal Precursor Cells
Neural stem cell
Somatic cell nuclear transfer (SCNT)
Somatic stem cells
Umbilical cord blood stem cells
|ASC (adipose stem cells)
CSC (cochlear stem cells)
CTP (connective tissue progenitors)
ESC (embryonic stem cells)
HSC (hematopoietic stem cells)
HB1 (AC133+ hemangioblasts from umbilical cord blood)
iPS (induced pluripotent stem cells)
|MSC (mesenchymal stem cells) |
MAPC (multi-potent adult stem cells)
NSC (neural stem cells/oligodendrocyte progenitors)
SKMB (skeletal myoblasts and muscle stem cells)
UCB (umbilical cord blood derived stem cells)
The National Academies:
Advisers to the Nation on Science, Engineering and Medicine
• Stem Cell Basics
• Understanding Stem Cells (PDF)
An educational primer designed to provide basic knowledge to facilitate thinking about and understanding the scientific and ethical issues surrounding stem cells.
The National Institutes of Health
• Stem Cell Information: Glossary
Updated December 2012