Today I would like to discuss stem cells and their uses. This is an extremely complex field and I can’t possibly cover it all, but I would like to discuss some basics about them. Stem cells are essentially undeveloped cells that, in some cases, have the potential to develop into any type of mature cell found in the body. As you can imagine, this potential has created a whole new dimension in the treatment and curing of human diseases and conditions. The first type of stem cell is the embryonic stem cell, or ESC. These cells are harvested from a human blastocyst, which is a human embryo at about five days after fertilization, or conception if you prefer. The blastocyst attaches to the wall of the uterus and becomes a human fetus. Harvesting ESCs has many ethical and moral issues, to put it mildly. Stem cells may also be obtained from umbilical cord blood immediately following birth. They may also be found in an adult’s tissues including in bone marrow, adipose (fat) tissue, and blood. These adult stem cells must be reprogrammed so they can be used to create other forms of tissue. After reprogramming they are called induced pluripotent stem cells, or iPSCs.
The word pluripotent means that the stem cell can form many types of human cells. Pluripotent stem cells are descended from totipotent ones. Totipotent stem cells can form every type of human cell and, in theory, could be used to form a complete organism, which is another ethical slippery slope. Every day, more uses are being found for stem cells. Let’s look at some areas where stem cells are currently being used. The first area is in skin diseases. Skin regeneration has been used to restore skin in patients with a heritable blistering skin disease called epidermolysis bullosa. Autologous (from the same person) stem cells have been obtained from skin biopsies and used to grow new skin. These were iPSCs. They are also being explored to grow new skin for burn victims.
Other uses for stem cells include repairing heart muscle damaged by a heart attack, repairing the retina in the back of the eye which has been affected by diabetes or macular degeneration, repairing skeletal muscles in muscular dystrophy, aging, and other muscle diseases, repairing nerve tissues in Parkinson’s disease and other neurologic conditions, repairing the pancreas to make insulin in type I diabetes, and treating various blood diseases like leukemias and lymphomas. Because the use of stem cells is really just in its infancy, the potential uses for them are endless, perhaps one day slowing down or stopping the aging process itself.
One downside to stem cell therapy is that, in most cases, the patient’s immune system must be suppressed, opening the door to infections. Also, in some cases, stem cells have grown into the wrong type of tissue, including tumors. A more general concern is the rapidly growing direct-to-consumer market, especially on the internet, for unproven stem cell therapies which are ethically dubious and potentially dangerous. This has the potential to both threaten and undermine the field of stem cell research.
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