Confused About Stem Cells? You're Not Alone!
This week, the U.S. Food and Drug Administration (FDA) approved the first U.S. product that’s made from stem cells.The product, Hemacord, is made from human umbilical stem cells and is designed to treat disorders of the hematopoietic, or blood-forming, systems in the body.This includes conditions such as blood cancers and autoimmune conditions that affect the blood.
Hemacord is made of what are called blood-forming progenitor cells. (Progenitor cells are primitive stem cells that can only “specialize,” not repair themselves like a full stem cell can--see the explanation below). When these cells are injected into the body, they travel into the bone marrow and then begin to divide and mature. Once they’ve reached their full maturity, these cells then travel into the bloodstream and help restore the function of blood cells. This boosts immune function and helps treat these hematopoietic diseases.
Stem cells are much in the news these days, either because of scientific advances such as this or because of debates about the ethics of stem cell research. You might have heard some of these news or debates and were confused about what exactly the issues are about stem cells and their uses. If so, you’re definitely not alone! Medicine that uses stem cells – called regenerative medicine – is on the cutting edge of scientific research, and it does have some aspects that are controversial.
To help clear this up, below is an explanation of the three major kinds of stem cells, how they work, and how they can be used to treat disease.
WHAT ARE STEM CELLS?
According to the National Institute of Health, stem cells are cells that have the ability to divide for indefinite periods of time in laboratory conditions, and they can be used produce specialized cells. Put more simply, this means that they’re “generic” or unspecialized cells that can renew themselves through cell division, even if they’ve been inactive for a long period of time.
Some organs have stem cells that regularly divide to repair or replace worn-out or damaged tissues. This includes places in body such as the gut or bone marrow. Other areas of the body, including the heart and the pancreas, have stem cells that will only divide under special conditions.
WHAT ARE THE TYPES?
There are three major types of stem cells, two that are naturally occurring and one that’s being developed in laboratories. Let’s look at these so that we can understand how they’re different and the controversies surrounding them.
1. Adult stem cells:
These are unspecialized (or “undifferentiated”) cells that are found in various organs and tissues in the body. They are fairly rare, and when they do divide, they have a limited ability to “turn into” other cells, meaning that what they can divide and mature into is typically limited to where they’re found in the body. This means that stem cells in the heart can only turn into heart cells, or that pancreatic stem cells can only turn into pancreatic cells.
2. Embryonic stem cells:
These are very primitive, unspecialized cells that come from what are called pre-implantation-stage embryos. That means they’re from embryos that have been fertilized, but which haven’t yet implanted in the lining of the uterus.
Unlike adult stem cells, these cells divide and develop into cells and tissues from the three “germ layers” – the endoderm, the mesoderm, and the ectoderm – that build all our tissues and cells. The endoderm, for example, becomes the stomach, liver, intestines, and thyroid gland. The mesoderm becomes the skin, the heart, and the skeleton. The ectoderm eventually becomes things like the eye, the nerve tissues, and the skin and the hair.
So you can see how these stem cells are particularly useful. If you can access these cells that are the building blocks for all of the cells, tissues, and organs in the body, you can use them for just about anything.
3. Induced pluripotent stem cells
These are a new development in stem cell research.Induced pluripotent stem cells are actually adult stem cells that have been “reprogrammed” by scientists to enter into an embryonic stem cell state. Basically what’s been done to them is that they’ve been forced to act like embryonic stem cells in terms of their ability to divide into basic types of cells.
Most of the controversies around stem cell use center around the use of embryonic stem cells because they require the use of an undeveloped human embryo as their source.
However, most stem cell therapies use adult or induced pluripotent stem cells andtherefore do not require the use of an embryo at all.
Embryonic stem cells can also be found in amniotic fluid and in umbilical cords and cord blood. In fact, cord blood is one of the sources (along with bone marrow and peripheral blood) for the progenitor cells used in the newly approved Hemacord product. Like adult stem cells, these types of stem cells do not require the destruction of an embryo for their use. Some people even “bank” their baby’s umbilical cord at special “cord banks” for just this purpose.
The uses for stem cells are, at this point, seemingly endless. Experts say they could be used for conditions as simple as tooth and hair loss to ones as complex as Alzheimer’s disease. Recent studies have found ways to restore function to the pituitary gland, help kidney transplant patients, and repair damage to heart muscles after a heart attack.
This week’s FDA approval of the Hemacord device is just the beginning to scientists finding new ways to treat disease with stem cell research. And most experts agree that as long as this type of research is done responsibly, there’s likely no limit to what it can do.
Sources: National Institute of Health; HealthDay News; Wikipedia; USA Today; U.S. Food and Drug Administration; Political Behavior; Gene Therapy; Yahoo News.