Stem cells are primal cells found in all multi-cellular organisms. They retain the ability to renew themselves through mitotic cell division and can differentiate into a diverse range of specialized cell types. In adult organisms, stem cells and progenitor cells act as a repair system for the body, replenishing specialized cells.
Stem cells are, in essence, the building blocks of the body. In adults, they are produced in the bone marrow, fat, and joint fluid. When released into the bloodstream, they migrate to areas that need repair. Research has shown that they hone in on areas of injury, and are more effective if placed at or near the damaged site. [ ] Once there, they become whatever kind of tissue needs help regenerating itself. Mesenchymal stem cells (MSCs) are the class of stem cells that most commonly repair cartilage, bones, and muscle. As we age, we produce fewer and fewer MSCs, which explains, in large part, why we have more trouble healing ourselves now than when we were children.
For many years, researchers and clinicians have known that stem cells can repair and regenerate damaged tissues. Most of these experiments have been done in animal models. Research has shown that stem cells can improve function of heart muscle after a heart attack , increse insulin secretion from the pancreas in diabetes , and heal brain tissue after a stroke . Only recently have there been published studies of bone and cartilage regeneration in humans using autologous adult mesenchymal stem cells.[ 1,2 ].
Currently there is a lot of confusing information about the use of stem cells in medicine. This arises, in large part, from the fact that while the concept of using stem cells sounds easy and appealing, the actual practice is much more involved. The result is a lot if misinformation that sounds promising at first glance, but does not make sense when looked at scientifically. Some examples are:
1. Pills or drugs to mobilize stem cells: There are new supplements claiming to regenerate every tissue in the body from muscle to brain to liver to kidney. The best of these have actually had blood samples tested using Fluoresence Activated Cell Sorting to show some increase in circulating blood stem cells. The problem? The types of stem cells mobilized into the blood stream are cells destined to produce more blood, not repair tissues. In particular, one of the MVP’s of the adult stem cell world (MSC’s) don’t circulate in the blood, so they stay put where they’re located. These supplements might help if you had anemia, but not much else.
2. Embryonic stem cell injections or cord blood injections: These are stem cells from someone else injected IV. Most of this is happening in third world countries. A few issues. One question is how these stem cells were isolated, as there has been at least one significant allergic reaction (which should never happen with a true stem cell) reported on a California company offering embryonic stem cells in Mexico. Assuming they are stem cells, the second issue is disease transmission. First, there are the common diseases such as HIV, Hepatitis, and other viral infections we can detect. Second, there is the issue of stem cells being able to transmit genetic disease such as an increased risk for osteoporosis (see earlier post). Finally, there isn’t much data that shows that if you have a bum knee, a bad kidney, and liver spots on your skin, that these cells will be able to home to one of these areas to allow repair. In fact, most studies show that even in severe injury models (where a severe life threatening injury is created like a heart attack or a lung injury) direct infusion of cells to the damaged area results in more repair than placing the cells in the blood stream.
3. Adult stem cell injections IV: I have seen clinics beginning to use various marrow concentrate systems to inject marrow nucleated cells into the veins (IV). Again, the issues with IV infusion as discussed above apply here as well. The other big issue that that MSC’s make up about 1 in 50,000 to 1 in 500,000 of these marrow nucleated cells. This means a very very dilute stem cell population is actucally being injected. As an example, 50 cc of bone marrow might contain trillions of cells, but only less than 0.0002% (in some older patients) are actually stem cells capable of tissue repair.
4. Bone Marrow concentration via bedside centrifuge: There are companies advertising systems (as above) that take whole bone marrow and magically produce millions upon millions of stem cells. Actually, the stem cells they refer to are CD34+ heme progenitors (stem cells that make more blood products) and not MSC’s which can repair tissue. So the same issues as above apply
