Are Fat Injections in Knee Joints Stem Cell Procedures?

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Physicians today, at a minimum, need to be able to define what a stem cell procedure really is and need to be able to assure their patients that their stem cell procedure likely works through the action of stem cells. Unfortunately, either unknowingly or deceptively, there are many procedures being performed that are called stem cell therapy that really aren’t. Examples include procedures using amniotic “stem cells,” PRP and other blood products, and the feature of this post—fat grafts, which is what many fat injections in knee joints and other joints actually are.

Today I am going to talk about why a fat graft is not a stem cell procedure. The short video above contains images and other information that will enhance your understanding, so be sure to watch the video as well.

The first question you might be asking is, What is a fat graft? So let’s start there.

What Is a Fat Graft?

In their raw forms, fat stem cells are much different from bone marrow stem cells in that fat stem cells are imprisoned inside a collagen matrix. On the other hand, bone marrow stem cells, once removed from the body via an aspiration, are free floating in a mix of cells.

Fat is most commonly harvested from the body via a liposuction. Following the liposuction, the fat can then centrifuged in a machine to separate it into layers. This leaves oil on the top, structural fat in the middle, and a water layer filled with red blood cells on the bottom. Once the top and bottom fractions are removed, what’s left is the structural fat.

At this point, that structural fat is often called a fat graft. While the fat graft does house stem cells inside the collagen matrix, those stem cells are trapped. The fat stem cells, according to our lab research, are imprisoned inside that collagen matrix (see the video images explaining the collagen matrix and how fat is imprisoned there).

I recently came across a physician reporting that by using a simple bedside fat centrifuge and a plastic kit, he was able to get two-thirds of a million viable stem cells per ml of fat. Knowing the machine he reported using, it’s almost impossible that he is getting any viable stem cells at all from this device, let alone 2/3rds of a million mesenchymal or other stem cells. Why?

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SVF vs. a Fat Graft

Regrettably, most doctors using stem cells today learned what they know from a weekend course and don’t have a deep knowledge of the topic. For example, I still find that most don’t understand the difference between a fat graft and Stromal Vascular Fraction (SVF). They are quite different. For example, one has stem cells imprisoned in collagen that are likely not useful to the patient and the other has stem cells that have been broken out of their collagen jail cells. One is fully FDA compliant and the other is currently illegal to use in the U.S.

Are Fat Stem Cells Released From Their Fat Graft Prison for Fat Injections in Knee Joints?

If we could release the stem cells from the collagen matrix, then they could go to work. But can we release them, and, if so, how? Technically, yes, the fat stem cells can be released from a fat graft. You can dissolve away the collagen prison that is trapping the fat stem cells with an enzyme, like collagenase. This mix is then centrifuged and washed, and, finally, among many other cells, you’ll find the once-imprisoned stem cells now at the bottom of the tube. However, as I’ve mentioned before, there’s a big and very serious problem with this kind of fat stem cell processing: it’s illegal per current US law because the FDA considers it an illegally produced drug!

To get around the legal issues, many clinics just liposuction the fat and centrifuge it (fat graft) and/or chop it all up very finely and inject it and, in either case, they often either unknowingly or deceptively, call the fat injections in knee joints or other joints, a stem cell procedure.

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Our Own Research on Chopped-Up Fat

In our advanced research lab, we’ve tested all of this exhaustively, and we’ve never been able to get any significant number of viable stem cells using any of the various methods used to chop up fat. In one research sample, you’ll see in the video, the fat was chopped up so finely that it appears to be an emulsified liquid. However, though it looks like it may have liberated cells, it is really just large microscopic chunks of fat with stem cells still imprisoned in the collagen matrix. In other words, no stem cells were released from their collagen prison cells.

Hence, regardless of how fine we chop the fat or macerate it with balls, we can’t call chopped-up fat a stem-cell therapy. At the very least, physicians must understand and agree that significant quantities of viable stem cells must be freely available to the body for any process to be called a stem cell procedure, and all physicians using stem cell therapy must understand and agree on its definition in order to protect consumers.

The upshot? So is a legal procedure that uses liposuctioned fat run through a centrifuge to do fat injections in knee joints and other joints a stem cell procedure? Absolutely not; it’s a fat graft procedure where stem cells are imprisoned in a collagen matrix. Is a procedure that legally processes the fat by chopping it up a stem cell procedure? Absolutely not; it’s a microscopic-chunks-of-fat procedure that still doesn’t release the stem cells from their collagen prisons. In fact, the only real fat based stem cell procedure is SVF, but regrettably, the FDA considers that illegal to use in patients.

This blog post provides general information to help the reader better understand regenerative medicine, musculoskeletal health, and related subjects. All content provided in this blog, website, or any linked materials, including text, graphics, images, patient profiles, outcomes, and information, are not intended and should not be considered or used as a substitute for medical advice, diagnosis, or treatment. Please always consult with a professional and certified healthcare provider to discuss if a treatment is right for you.

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10 thoughts on “Are Fat Injections in Knee Joints Stem Cell Procedures?


    why insurance company not approved this producer

    1. Regenexx Team Post author

      Stem Cell Procedures are not covered by Insurance in the USA.

  2. Vetta

    Regardless of what they call it does it work?

    1. Regenexx Team Post author

      Fat injections are not stem cell procedures, therefore any expectation of the regenerative potential of stem cells would be misguided.

  3. David Pagano

    Good afternoon,
    I’m going through Proton Therapy for Prostate cancer in Loma Linda ca. I should be done mid July. I have two tears in my left Rotator Cuffs and one of the tears on the right. My closest Regennex clinic is in Mtn View CA My home is near Turlock CA.
    I have an Mri of my situation that’s within your two year requirements. I will want both Stems and Blood platelets. I will want to begin when I return from my Cancer therapy. How long will I need to wait., I want to begin with my left arm first. Please have someone call me Thank You

    1. Regenexx Team Post author

      We will have our team email you, so they can answer your questions, and assist in getting you set up.

  4. Rob

    How am I to know what Dr or Institute
    are the best? Which ones are poor?
    Is there a list of all research and procedures?
    Do I just keeping reading yours and look at others?
    Frustrated Rob with bone on bone

    1. Regenexx Team Post author

      Here is the list of Providers which can perform Regenexx procedures. Stem cell procedures in general are not Regenexx procedures, and therefore can not be expected to produce the type of results we cover on our website and in the blogs. Please see:

  5. Rich Hale

    Last September, I had a “stem cell procedure” for arthritis and bone to bone in both knees. They took bone marrow from my hip and fat cells from my stomach and used a bedside centrifuge to combine for the injections. I had 4 injections in one knee and 3 in the other. My knees feel much better, the pain was keeping me up at night.
    After reading your website, I am wondering if I got the full benefit. I had my procedure at the Cleveland Clinic affiliate at Hillside called Regen Orthro. Unfortunately, I went on patient recommendations and did not research other options. I did not find out about Regenexx until after I had my procedure.
    I enjoy your daily blogs.

    1. Chris Centeno Post author

      Yes, the use of simple bedside systems may have reduced the effectiveness of your procedure. That’s why we don;t use them. Having said that, it sounds like you got some relief, which is great!

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