What is the Future of Stem Cell Treatment For Regrowing Cartilage?

Osteoarthritis is the most common form of arthritis. Estimates of its prevalence among Americans vary from 20 million to 40 million.

The underlying pathophysiology is the premature deterioration of articular cartilage, the gristle that caps the ends of long bones. Cartilage is a form of connective tissue. It is unique in that it receives its nourishment from the lining of the joint- the synovium. Cartilage itself has no blood vessels or nerves.

The pain that arises from osteoarthritis is due to irritation brought about by local inflammation. These local inflammatory changes occur as a result of the production of destructive enzymes as well as local irritation due to altered biomechanics.

Until recently, the treatment of osteoarthritis has been purely symptomatic. Non-steroidal anti-inflammatory drugs either in oral or topical form, local joint injections of glucocorticoids, or intra-articular injections of viscosupplements (lubricants).

While helpful for alleviating pain temporarily, these approaches also are associated with potential side effects, and do not address the underlying problem- loss of articular cartilage.

In the 1990's there was interest in developing what are called disease modifying osteoarthritis drugs (DMOADS). However, research efforts directed at these disease modifying remedies were disappointing.
More recently there has been interest in the use of stem cells (SCs) to help with cartilage regeneration.

The questions, though, with this line of thinking have been many. What type of SCs should be used? What keeps the SCs inside the joints? How can the SCs be made most productive? When do they stop working? How do you provide the right environment for the SCs to make cartilage? What are the dangers of involved? What criteria are involved in selecting the right SCs expert?

The major breakthrough recently has been in the field of human pluripotent stem cells (hPSCs). The original work done by Shinya Yamanaka in 2007 has laid the groundwork for some excellent investigations involving the use of this techniology. Basically what Yamanaka was able to demonstrate was the ability to take adult stem cells, and reprogram them- essentially rewinding the biologic clock- so that the adult stem cells now behave like embryonic stem cells. The advantage is that these induced adult stem cells can become any type of tissue given the right environment.

However, there are technical problems with this approach and the reality of being able to use these types of stem cells, particularly for arthritis, is way off in the future.

So what is available now and how good is it? Currently, the use of mesenchymal stem cells (MSCs), adult stem cells located in the bone marrow and, which, if placed in the right location with currently available growth stimulators, appears to be effective.

MSCs are multipotential. They can become a limited number of tissue organs. Fortunately, cartilage appears to be one of them.

How effective the approach is, is difficult to say since there are no good long term randomized controlled studies. What is available are anecdotal reports. Unfortunately, these anecdotal reports fall far short of what would be considered good science.

Also, the application of MSCs where there is no cartilage left and there is an angulation deformity is problematic. In our hands, these patients do not respond.

Age and body mass index (weight) are two other important factors to consider.

What is known is that the approach is safe and appears effective for the short term (2-3 years). Clinical measurements, along with cartilage thickness improve.

Also, there is no evidence of cancer, which is the concern using the induced pluripotential approach.
So... the bottom line...the best current approach appears to be the use of adult MSCs made by concentrating marrow, along with growth factors derived from platelet rich plasma. In addition, the utilization of adipose tissue (fat) to serve as a scaffold is strongly advised.

Finally, the technical harvesting and administration of MSCs using diagnostic ultrasound guidance by an experienced and expert physician seems to be the most important ingredient necessary for a successful outcome.