Stem Cells: A Therapy for the Spine
One of the most common things patients ask me about are stem cells. At this year’s American Academy of Orthopedic Surgery, I had the chance to meet with Carl Llewellyn, President and CEO of Lipogems SPO. Lipogems is the leading company specializing in the processing of a patient’s own adipose tissue to get stem cells and growth factors. They hold FDA clearance for their “Microfragmentation” technique for harvesting living cells along with growth factors from a patient’s fat. I wanted to share my thoughts on stem cells, some of the history and problems with stem cells in the past, and why I am excited to start offering this technology to my patients.
Stem Cells in the Spine
First off, I want to explain why stem cells make sense in the spine. People who study the spine have known for decades that the disc has particular problems with healing. The disc is a cushion that is between the bones of the spine. It allows movement in different directions and also acts as a shock absorber between the much more rigid bones. I often make the comparison that discs function much like a bushing or like the cushy sole of an exercise shoe. On a microscopic scale, the disc is made up of very long molecules of collagen that attract water. On this level, it functions like a sponge. Think about how a wet sponge is soft like a cushion. As we age, repeated strain on these long collagen molecules causes them to break down resulting in decreased ability to absorb water. As a result, the “wet sponge” disc becomes more of a “dry sponge.” When you think of a dried out sponge, it is not soft at all. In addition, the dried out disc shrinks down just like a dried out sponge shrinks. This is the main reason that we get shorter with age!
What the disc does not have is many actual cells. It also has essentially no blood supply. The collagen matrix is all outside of the cells and in an adult, there are only very rare cells available to maintain and repair it. With minimal blood supply, there is also very little way to get new cells into a damaged disc or to feed the few cells that are there when they need to repair the disc. The end result is that, with time, our discs start to wear out and never really heal. Even in people with no history of back pain, MRI studies almost always demonstrate disc degeneration by the time people enter their 30s.
Initially doctors did not know of a good source of stem cells, so early clinical efforts in this area focused on the problem of the growth factors and relied on the body to still supply the cells. This is the rationale behind platelet rich plasma (PRP) and “fibrin glue” injections into the disc. Platelet rich plasma is a concentrated component of blood that contains platelets. It is primarily responsible for creating a scab when you get a cut. It acts as a glue sealing a wound, provides a scaffold for the body to form new tissue on during healing, and also stimulates the local tissue to start to heal. This works great for cuts in the skin and has also been shown to help heal tendon injuries in areas where the tendon has a good blood supply.
The problem is, that in areas where the blood supply is poor – like the intervertebral disc or the cartilage of joints like the knee and hip – there is only so much the platelet rich plasma can do. Thrombin glue made of fibrin, a component of blood clots is similar to PRP but without the platelets. It is the technology behind the “Discseel” procedure. It has been used for decades to seal tissue during surgical procedures, but for injection into joints and the disc, it makes even less sense than PRP. The advantage thrombin glue has is that it can be made without taking any blood from the patient. The problem with these growth factor or tissue matrix technologies is that they still rely on the local blood supply to bring in the cells that are needed to actually complete the tissue repair. But blood supply to the disc is poor and gets poorer with age. In addition while blood is great at supplying oxygen and carrying the infection fighting white blood cells, it is not a very good source of stem cells.
So, in addition to the scaffolding that stimulates healing, the disc also needs cells. It would seem that in an ideal situation, we could get some chondrocytes – the cells that make collagen – from a healthy disc and inject them into a damaged disc and all would be good. Unfortunately it is not that simple. First off, the cells are so rare in the disc as is, making them very hard to get out in any good numbers. Also, you would have to either use cells from a donor – that would likely be rejected when they were injected into a different patient – or you would have to cause damage to one of the patient’s own discs – which would be counterproductive. Second, the cells are very hard to grow in culture and there is always a risk of contamination of the cells during the growth process. Lastly, the discs actually need more than just stem cells. Remember the platelet rich plasma that helps provide the scaffolding for tissue repair? The disc needs that too.
It turns out that the an excellent source to get both stem cells and growth factors is found in a surprising place: a patient’s own fat. When you think about it, this makes sense – after all, we are all aware how easy it is to grow fat, so there must be growth factors in there. Fat acts as a reserve of energy for times when we can’t eat enough calories. To this end, it has an excellent blood supply making it easy to mobilize the fat into the blood supply and distribute it where the energy is needed. And when fat grows, it has to grow the blood supply as well. So fat tissue contains the needed components: the scaffolding which we call the “stromal structure,” and the cells including endothelial cells – which line and help grow blood vessels – and the “mesenchymal stem cells” or MSCs – which can grow into the chondrocytes that can actually grow new collagen to repair damaged joints.
For years now people have been working on techniques to get this ideal stem cell mix. The key has been illusive and that is why it was not until November of 2017 that the FDA finalized its rules guiding the use of Human Cellular and Tissue Products. Key to these rules is the idea of minimal manipulation of the tissue. This means that the tissue that is being used can not be over processed. This is because over processing damages the components of the tissue and decreases the tissue’s reparative ability. So, it is not just how you get the fat out – that is actually the easy part. It is how you prepare and filter the fat to get the cells and stroma that you need.
Here is where Lipogems comes in. A simple technique using water pressure and filters to separate the stroma and cells from the lipid part of fat quickly and effectively has been developed. Once prepared, this mixture can be immediately injected into the patients damaged joints. Because it uses your own tissue, there is no risk of rejection and because the processing is minimal, there is a very low risk of infection.
As of right now stem cells obtained from the Lipogems system are FDA cleared for injection into “diarthrotic joints” which are joints like the shoulder and the knee and also includes the facet joints in the spine. Use of this product for the intervertebral disc is considered an “off label” use. It should also be noted that insurance companies still consider stem cell therapies to be experimental and therefore these procedures are not covered by insurance. Fortunately they are simple enough that they can be performed as an office based or outpatient procedure, which avoids the costly hospital component of the expense associated with traditional surgery.
How does it work?
In the spine, only a small volume of fat tissue is needed. Under local anesthetic, a solution is injected into the waist area’s fat, making it easier to remove the fat with a special needle. This needle is then used to obtain about one tablespoon of fat. This fat is then processed and filtered to remove the blood, lipid, and cellular debris. The remaining stem cell and stroma-containing tissue is then injected under X-Ray guidance into the treatment site.
Who is a candidate for stem cell therapy?
Stem cell therapy is appropriate for patients with symptomatic degenerative disc and facet joint disease. These patients will primarily have pain in the area of the spine more than nerve pain. An example would include a patient with a dark disc or with facet arthritis seen on MRI whose back hurts with loading such as lifting. Another example is a patient with a history of disc herniation or discectomy whose nerve pain has resolved but whose back remains painful due to the loss of disc between the bones.
Who is not a good candidate?
Stem cell therapy is not appropriate for patients whose pain is due to nerve or spinal cord compression. For example, a patient with spinal stenosis or a disc herniation who is experiencing primarily nerve symptoms such as sciatica or difficulty walking due to leg pain would not qualify. These conditions are best treated with decompression-type surgery which can often be done with minimally invasive techniques. It is also less likely to be appropriate for a patient with an instability of the spine such as a significant scoliosis or spondylolisthesis. These conditions are generally treated with deformity correction and stabilization which, like decompression, can often be done with a minimally invasive technique.
What are the risks of stem cell therapy?
The biggest concern regarding stem cell therapy is that it simply may not work. Because this is a new technique, there is limited research on effectiveness – specifically regarding what percentage of time it works and how long it typically lasts. As far as complaints around the procedure, it is not uncommon for patients to report pain in the area of fat harvest or in the area of the back that was injected. There may also be bruising. There is a risk of nerve injury but this is minimized by doing the procedure with the patient awake so they can indicate if we get too close to the nerve. There is also a risk of infection in both the harvest site and in the site where the cells are injected.
What else needs to be considered?
- Stem cell therapy is generally not covered by insurance. It is done in the office to minimize costs but it still can be financially forbidding for patients.
- Someone who has had stem cell therapy can still undergo other treatments of the spine in the future including more traditional surgery if needed.
- Anyone who is taking medicines to thin the blood will need to hold these medicines for the procedure. This will be done in consultation and only with clearance from the doctor that prescribed the blood thinners.
- Anti-inflammatory medications including over the counter medicines like ibuprofen and Naprosyn and prescribed non-steroidal and steroid medications may limit the effectiveness of stem cells and should be held around surgery.