Why Bone Marrow Concentrate Injections Are Not Really “Stem Cell Injections”

In the U.S., many clinics advertise bone marrow concentrate (BMC) injections as “stem cell injections.” That sounds exciting, but it isn’t really accurate. Here’s why.

When we take a sample of bone marrow and process it into bone marrow concentrate, the fluid does contain a small number of adult mesenchymal stem cells (MSCs). These are special cells that can help guide healing. However, they make up only a tiny fraction of the overall mix. In fact, studies show MSCs make up about 0.01% to 0.001% of all the active cells in bone marrow.

To put this into perspective, let’s look at the numbers. In a typical 50-year-old patient, we might collect around 500 to 600 million total active cells (called nucleated cells, which simply means cells with DNA that can help with repair). If MSCs make up only 0.01%–0.001% of that total, the math works out to about:

• 50,000–60,000 stem cells at the high end

• 5,000–6,000 stem cells at the low end

That may sound like a lot, but compared to hundreds of millions of other helpful cells, it’s a drop in the bucket. So to label the entire injection as a “stem cell procedure” is misleading.

The truth is that healing is a team effort. Stem cells are important because they can “direct traffic” for other cells. But other types of bone marrow cells are just as crucial. For example:

• Macrophages act like cleanup crews, clearing out damaged tissue.

• Eosinophils send out important repair signals.

• Other progenitor cells help rebuild tissue directly.

Together, these cells act like a symphony orchestra, with each section playing a role in the body’s healing response.

Now, a true stem cell injection would mean separating out only the stem cells from the bone marrow, multiplying them in a lab, and then injecting them back. While this can be done, the FDA does not allow it in the U.S. at this time. That’s why all legal procedures here use fresh bone marrow aspirate derived BMC instead.

Interestingly, some overseas clinics are allowed to expand stem cells in labs. But in my opinion, even in those cases, the best results would come from combining those multiplied stem cells with fresh bone marrow concentrate, so the “conductor” (the stem cells) still has the “orchestra” (the other cell types) to work with.

In summary: BMC injections are not pure stem cell injections — they are a powerful mix of many cell types working together. And that may be the real reason why these procedures are so effective: because healing is rarely about one superstar cell, but rather about the teamwork of many.

Sources:

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2. Muschler GF, Boehm C, Easley K. Aspiration to obtain osteoblast progenitor cells from human bone marrow: The influence of aspiration volume. J Bone Joint Surg Am. 1997;79(11):1699–1709. doi:10.2106/00004623-199711000-00012

3. Pittenger MF, Discher DE, Péault BM, Phinney DG, Hare JM, Caplan AI. Mesenchymal stem cell perspective: Cell biology to clinical progress. NPJ Regenerative Medicine. 2019;4:22. doi:10.1038/s41536-019-0083-6

4. Hernigou P, Poignard A, Beaujean F, Rouard H. Percutaneous autologous bone-marrow grafting for nonunions. Influence of the number and concentration of progenitor cells. J Bone Joint Surg Am. 2005;87(7):1430–1437. doi:10.2106/JBJS.D.02215

5. Gan Y, Dai K, Zhang P, Tang T, Zhu Z, Lu J. The clinical use of enriched bone marrow stem cells combined with porous beta-tricalcium phosphate in posterior spinal fusion. Biomaterials. 2008;29(29):3973–3982. doi:10.1016/j.biomaterials.2008.06.005

6. Sensebé L, Gadelorge M, Fleury-Cappellesso S. Production of mesenchymal stromal/stem cells according to good manufacturing practices: A review. Stem Cell Research & Therapy. 2013;4(3):66. doi:10.1186/scrt217