Next Steps for Stem Cells

The most likely sources of stem cells for cartilage regeneration are adipose tissue (fat) and bone marrow.  Each of these offers the possibility of harvesting the cells from the patient and injecting them or implanting them as a component of an advanced tissue repair product.  We know that growth factors alone (PRP, or platelet rich plasma) are effective in wound healing, and we know that cell based cartilage repair (like Denovo) can be effective in cartilage repair; as also seems likely, that a combination of scaffold coordinated bone marrow stimulation can also work.  The building blocks of tissue repair are now obvious and accessible.

One continuing issue for industry is that the regulatory pathway of an advanced hybrid product will be very expensive, perhaps unrealistically so, as the orthopedic companies involved in the sales and marketing of the new biologics are not funded for nor are they comfortable with the type of clinical trials that FDA has historically required.  These trials are not required if the patient’s own cells are used and are not manipulated, changed, augmented or otherwise turned into a potentially harmful new product or device. The effect of this situation is that many or most companies are NOT interested in any product with a tough regulatory approach- this is quite the opposite from the pharmaceutical industry. I do not see this attitude changing in the near term.

So back to Stem Cells.  Inducing pluripotent stem cells is much in the news, but will run straight into the regulatory issues just mentioned and hence is not likely to be introduced into orthopedics at this time.  Adipose tissue is readily available from many patients (but not all!) and separation techniques can be performed at the bedside to separate out a cell enriched fraction. I am not sure that the average orthopedic surgeon wants to get into liposuction, so the details involved are somewhat beyond me.

As for bone marrow, that is accessible in all of us. The usual donor site is from the prominences of the iliac bone, just below the skin. Under local anaesthesia, a needle device can be introduced into the bone; what hurts is the aspiration of the marrow.  I am currently working on ways of minimizing the discomfort ( translation = pain) to make this more tolerable.  These marrow cells are quite diverse, and the stem cell population may only be 1 in 10000.  Nevertheless, with the PRP technology currently available, we can mix the marrow with some peripheral blood and develop a purified concentrate for “bone marrow aspirate” and PRP in a very low volume.  In this way we now have an enriched population of cells that should be an excellent construct for cartilage repair, growth factors inc