The Bone Marrow Harvest Doohickey Science Challenge…
We’ve seen a flood of new devices enter the market to harvest bone marrow stem cells. Any of which, if they actually worked, would be game changing for what we do, as obtaining 2-3 times as many stem cells from the same bone marrow aspiration (BMA) volume would be great for our patients. However, so far we’ve been disappointed. In the meantime I’ve detected a type of scientific problem in all of the studies performed on these devices that is a deal breaker and invalidates all of the manufacturers studies I’ve seen. Let’s call it a “false equivalence” logical fallacy.
Bone marrow aspirates have been taken the same way for many years. A trocar is inserted into the bone and the “aspirate” is obtained via a syringe which looks like thick blood. We’ve known since the 90s that the best practice way to do this procedure to optimize stem cell yield is to aspirate smaller volumes from multiple sites. This must be performed under imaging guidance to make sure that all of the right spots are hit. The biggest problem recently has been the “experts” hired by the companies that make automated centrifuges to isolate stem cells didn’t get the memo. Hence we have hundreds of physicians who have been trained the wrong way — to draw one large pull of marrow from a single site. Why? It’s easier for the doctor, but regrettably it’s bad for the patient as it virtually assures that there will be far fewer stem cells for treatment. In addition, many physicians have been trained that it’s OK to do this blind.
Enter a new breed of expensive and fancy bone marrow harvest devices. Given that the concept behind the trocar hasn’t really been updated since the turn of the last century, there would seem to be a tremendous opportunity for innovation and new disruptive technologies. We certainly would welcome the idea that a well designed device (doohickey) could allow us to harvest many more stem stem cells. The companies that make these devices have also lined up doctors to endorse their products, pretty much par for the course for any new medical device, as physicians are generally as susceptible to personality marketing as any lay person. Unlike these doctors, we of course test all claims that manufacturers make in our own lab before we reccomend any new device to our network physicians, as we’ve seen many instances where what the manufacturer claims and reality seem only to be distantly related.
We’ve now tested many different methods and a a few new devices for harvesting marrow, comparing these against our standard best practices marrow draw (multiple sites, low volume under imaging guidance). So far, the new devices have failed to impress. Why? Well, in hind sight it’s easy to see how the manufacturer’s claims from all of these devices have the same issue which causes them to fail once they get into real world clinic testing. This is where the “false equivalence” logical fallacy comes in.
False equivalence – describing a situation of logical and apparent equivalence, when in fact there is none. In this case, the manufacturers fund a study to compare their device to a really bad, below standard of care bone marrow draw. These trials fall into two categories of poor comparison: a single high volume draw or a multi-site draw performed blind without guidance. Since these types of stem cell harvests are guaranteed to reduce stem cell yield per cc of marrow aspirate, the comparison to the device looks great, as the device doesn’t make that mistake. Hence the manufacturer claims that the new device gets 2-4X the number of stem cells when compared to the old fashioned bone marrow draw using the trocar. However, when we compare the device against a more sophisticated standard of care draw technique, we don’t see a big difference in the number of stem cells being harvested. The manufacturer is shocked, when he or she shouldn’t be, as the device has never before had to beat a properly performed draw.
The upshot? I think most manufacturers and designers of these devices aren’t very experienced in bone marrow aspiration, hence I don’t think any of them are consciously trying to deceive. I think they just don’t know any better and may have consulted physicians who aren’t schooled in the newer and more reliable ways of harvesting bone marrow stem cells. Hence, they are thrilled when they see their device beat the snot out of the stem cell numbers obtained by the single site (below standard of care) or blind draw. They then spend gobs of money patenting, prototyping, approving, manufacturing, and marketing these fancy devices. The slick videos they use for marketing look fantastic, but in the end, so far all of the devices we have tested have failed against a high standard of care draw, carefully performed under imaging guidance using an inexpensive disposable trocar. So here’s my challenge to all BMA “doohickey” manufacturers. If you think you have a device that can beat the pants off our standard of care BMA, you sample the devices and we’ll test your device at our expense for 4-5 patients. Given that we’ll test the output with inversion microscopy, nucleated cell counts, flow cytometry, and CFUs/total MSC count-this is about $10,000 in testing that will cost you nothing. The goal? Much like the man versus machine tests of the early 20th century, we would welcome a better stem cell harvest mousetrap! However, to date, we have yet to actually see one!