Belly fat stem cells improve spinal injury recovery

Could an injection of stem cells grown from your own abdominal fat be the key to improving outcomes for people with spinal cord injuries? In an early stage trial in America, scientists have found that over two thirds of the small group of patients they treated showed improvements. They think that the stem cells are boosting the blood supply to the injured region of the spinal cord, and helping to control inflammation, which may lead to reduced scarring and better prospects for recovering some of the lost nerve connections. Mohamad Bydon is a neurosurgeon at the Mayo Clinic and led the new study…

Mohamad - The historical teaching around spinal cord injury is you deliver surgery, you do physiotherapy, and that's basically it. And things haven't really advanced in a long, long time. So what we wanted to do was really impact the space and say, are there other treatments that we could add to augment the recovery, to aid the recovery, to improve the recovery?

Chris - And your intervention? What's the rationale behind what you're doing and how are you doing it?

Mohamad - So at a very high level, at a 30,000 foot view, the question becomes, what are the other things that we can add? And that's where we believe regenerative medicine will be a part of this paradigm. It's not going to be the only answer: you still need your surgery, you still need your physical therapy, there's other things like stimulation that are being discussed, but we believe regenerative therapy, specifically with stem cells, will be beneficial in helping to improve outcomes for patients.

Chris - So what stem cells? Where from and what do you do with them?

Mohamad - So stem cells are cells that can become a number of different things once they enter the body and they come from a number of different areas. Specifically in this study we used what are known as mesenchymal stem cells, adipose derived. Those words mean stem cells from your own fat, belly fat. I had a colleague who said to me recently, 'Who knew that belly fat could be so useful?' So, from your own belly fat, we remove that and expand the cells until we get to the right number of cells and then we proceed to reinject those cells once they're expanded and cultured into the spinal cord.

Chris - How many cells were you putting in once you'd grown them or expanded them and where exactly were they going? Were they going into the substance of the spinal cord or around it?

Mohamad - There were 100 million cells. Frankly, we need to work on dosing still, but a hundred million is the dose that we expand the cells to. Once we do that expansion, we proceed to inject it into the faecal sac. There's the substance of the spinal cord itself, and then there's a sac that surrounds the spinal cord - it's called the faecal sac or the dura mater - and that is a lining that surrounds the spinal cord. It also surrounds the brain. Inside that layer there's something called cerebrospinal fluid. So what we do is we put these cells inside the dura, into the fluid, and then the cells go to the area of highest injury and area of highest inflammation, which is the area of injury.

Chris - What do the cells look like? Are they still very much stem cells at this time when you're doing this? And then when they go to the areas of injury, is this only in people who've just had an injury or will they go to areas of injury that happened years ago?

Mohamad - Good question. The cells definitively are stem cells and there are certain markers and hallmark features that stem cells have. To your question on longevity, our current trial is in patients who've had their injury within a year. Many trials deliver therapy to patients who've had the injury right away; you had your injury yesterday, we're going to give you therapy today. This trial was not designed like that because some patients have natural improvement and so the earliest we injected any patient was at seven months. The latest that we injected any patient was at 22 months. Some of the patients that we injected out to 22 months had a very significant response. Now, we haven't done studies looking at longer, although now we're starting studies to look longer out. So what would it look like if we did patients after five years, ten years? What would that look like? Those are also things that we're evaluating and looking to treat.

Chris - Do you know for sure that the stem cells when you put them in actually go to the injury side or do they just go everywhere and some randomly crop up at the site of the injury? Have you actually followed them to see what happens to them and how long they persist for after you put them in?

Mohamad - We've done testing on this and we know that the cells go to the site of injury at the same time. The cells have an impact across the spinal cord and the brain and that's okay. The impact that we've seen has been positive or had no impact. So, we haven't seen it be negative. The cells themselves then work through a couple of different potential mechanisms once they get there. There's potentially a regenerative mechanism through the stem cells themselves regenerating that area, but the other potential mechanism is a vascular mechanism where the stem cells induce a more vascular area where scar tissue would normally be a very nonvascular area without blood vessels. Blood vessels are important because they deliver good nutrients, they take out bad nutrients, and so areas of injury tend to wall themselves off and lose their vasculature. These cells can be very helpful because they can reset the vasculature in those areas, allowing the areas to heal more properly.

Chris - For the patients, what were the outcomes like and in what ways did people improve in ways that you wouldn't have anticipated had they just been managed the way we normally, historically, have been managing spinal cord injuries?

Mohamad - What we looked at, in terms of safety, we found adverse events. Mostly, they were headaches or back pain that would improve over a few days. We never saw any significant or long-term side effects. On the effectiveness side, in terms of our secondary endpoint on effectiveness, what we found was that seven of the ten patients showed some improvement, three of them being very significant improvement, four of them being mild to moderate improvement, and the other three patients showed no improvement but did not get worse. Some patients who required a harness and multiple assistance to be able to bear weight and get up could now walk without that: they could walk on their own. Other patients had improvement in bowel and bladder function.

Chris - How do you know, though, that you didn't, just by chance, select people for this study who are that bit fitter? They're more likely to have a good outcome and, had they been just left to their own devices with the gold standard care they would otherwise have had, they would've ended up at the same endpoint?

Mohamad - This is a good question, and this is a question that we debated at length with the regulatory bodies. Most studies in this space treat patients right after the injury, in which case your question becomes very relevant. In our case, we waited. Most of the improvement after a spinal cord injury occurs within the first six months. Much less improvement occurs as you keep going over time, much, much less. The earliest we ever treated a patient was seven months and we had patients that we treated as late as 22 months and everybody had plateaued. Nobody was continuing their improvement. Remember, this is a phase 1 trial of ten patients. The definitive trial would be randomised controlled, which we're doing now, which is a phase 2 randomised controlled trial of best medical management versus our interventional therapy. But this is a signal and this is an important signal that will inform our future trials.