Wednesday, April 9, 2008

Stem Cell Hype vs. Medicine

As the medical director of a stem cell company building procedures that are less invasive and target specific tissues for regeneration, I see allot of hype out there. Here are some examples of stuff that sounds good to the lay reader, but when one looks at the basic science, don't add up:

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.

So as you can see, there's allot of hype. We at RSI continue to work hard to do the following:

1. Isolate and culture expand true mesenchymal stem cells (MSC's) from the same patient where they are harvested (meaning we can harvest a few hundred thousand stem cells and culture expand them to between 5-200 million in just a few weeks). This is done without exposing the cells to potentially harmful drugs or recombinant growth factors.
2. Test various procedures to place MSC's into the area being regenerated. As an example, the procedure for regenerating disc tissue is wholly different than the procedure that targets cartilage in the knee. As more examples, regenerating a partially torn rotator cuff is different than regenerating bone. We then use patient reported outcomes ("I feel great!") as well as before and after 3.o T MRI (the best quality MRI technology currently available) to convince ourselves that we have repaired the target tissue. We are also constantly pioneering new techniques to get the cells to the target area via injection (such as MRI planned fluoroscopy-this is where we use the MRI image to guide the placement of cells).

Stem cells have great potential, but with that opportunity comes the hype...