Disc Stem Cell Review: The Hype has Begun: Beware!
POSTED ON 9/23/2014 IN Spine BY Christopher Centeno
Looking for a disc stem cell review? The low back disc stem cell bonanza has begun! After about a decade using stem cells in degenerated low back discs, I've got a pretty good idea of what's possible with our existing technology and what's not. This past week I saw an ad that was pointed out to me on a Linkedin discussion board as being irresponsible. I was floored at the claims being made by the physician who put up the web-site. Let me explain. The concept that discs might be able to be regenerated with stem cells began about a decade ago with some interesting animal research. The study authors created artificial degenerated discs in rabbits and then injected cultured bone marrow stem cells into the discs with collagen. The discs seemed to regenerate in that they gained lost height and they looked like they were holding onto more water on MRI. This is actually the study that got me interested in using stem cells in discs in 2005. Regrettably, what happened in animals and what happened in real patients were two different things. I've detailed that low back disc stem cell experience in earlier blogs. Enter this advertisement above. The statement made on the main page with the smiling faces is, "Stem cell therapy can regenerate damaged spinal discs..." So let's explore that statement and where it likely comes from. First, since this physician states he uses bone marrow stem cell therapy from a centrifuge. Can he base this broad and seductive statement on what's published on the use of none marrow concentrate in discs? There is a single small case series recently published by Pettine and sponsored by a manufacturer of an automated bedside centrifuge. So let's look at the study. First the study was tiny (only 26 patients) and describes itself as a pilot study (meaning the authors acknowledge that you have to take the results with a grain of salt). The author took concentrated bone marrow and injected it into low back discs of young patients (average age under 40) who had anywhere from mild to moderate degenerated discs (modified p-score of 4) to moderately degenerated discs with about a maximum of 30% loss of height (p-score of 7, but modified by the authors). Curiously, even though the article claims to be treating discogenic pain, the gold standard test to determine if the patient has a painful disc (pressure discography), wasn't performed. So what were the results? Only 8 of the 26 patients (6 never had their MRI repeated) showed small improvements in the appearance of the disc on MRI at one year. These changes were on average about 1 grade in the 8 point score used. Of concern, this disc grading score has some accuracy issues, especially when trying to get two readers to agree on what the score should be when there is a one point difference. In addition, the example MRI shown in the paper is a very poor quality image from an older open scanner, so the detail of the image is marginal. More concerning is that different image sequences are shown (one where water is bright and the other not) for the before and after pictures, so the two images can never be compared for improvement, as they're apples and oranges. Hence the small changes seen in 31% of the treated discs may or may not have been real. In addition, the standard for this type of study would be to have at least two readers read the same MRI films to see if they agreed on the improvement, this wasn't done. Perhaps most concerning is the fact that some patients over 40 showed a small worsening of their discs. Two patients also ended up with low back surgery despite the therapy. The upshot? Does the Pettine study give our disc doctor above good information on which to base advertising that stem cells from a bedside centrifuge can regenerate discs? Nope. The study that he's likely relying on is very small and not high level. Even if you take it at face value and assume that it could hold up with 100-200 patients (a very big "if"), the changes seen in discs are also small and the patients treated were young. Heck, looking at how the study was performed, it's impossible to conclude with any certainly that the changes in the disc were real, given the grading scale, a lack of a second MRI reader, and the poor quality of apples to oranges images shown in the paper. That last SNAFU can't be overemphasized, as the before and after images shown in the paper are from two very different MRI sequences that can't be compared for improvement! While patients reported relief, we have no sense of whether that was due to the stem cells injected or the platelets leaching out of the disc into the epidural space or something else. The authors discuss that we should conceptualize that the improvements were likely due to stem cells since patients who had better stem cell content in their bone marrow did better, yet this could also be a measure of platelet content (which wasn't measured in this study). Given that most patients saw improvements in two weeks which is far too early for any significant disc remodeling to have occurred, I would argue that this weighs heavily in favor of the growth factors from the platelets in the bone marrow causing the pain effects, as this is very similar to what we see with platelet growth factor epidurals. If that's the case, why injure the disc by poking a hole in it, why not just inject platelet growth factors around the irritated nerves (epidural)? Good question! In addition, in my clinical experience, most patients who want disc stem cell therapy have discs that are severely degenerated and collapsed (way beyond the level of disc degeneration treated in this paper) and are older than 40 (the group that didn't do as well in this study). In conclusion, while this is an encouraging entry in the literature (I applaud Celling Biosciences for publishing this study), this small research paper can not reasonably be used to support the advertising referenced above. Caveat Emptor...
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