Here you will find a list of commonly asked questions regarding the Regenexx Procedures. If you have a question that is not answered below, please contact us at 888.525.3005.

Are the Regenexx procedures performed in the U.S., FDA-approved?

All of the Regenexx Stem Cell and Blood Platelet Procedures performed in the U.S. today are same-day procedures that are compliant with CFR 21 Part 1271, falling under the same surgery exemption discussed in 1271.15 (b). Unfortunately, there still remains some confusion about Regenexx, largely as a result of a few individuals who have written about our case against the FDA throughout the last few years, but who did not fully understand that the case relates only to the Regenexx-C Procedure. This single procedure, which is different from the procedures now performed in the USA, is only available in the Cayman Islands through an independent vendor who has licensed the procedure and has not been performed in the U.S. since August of 2010.


Regenexx FDA Clarification

What’s the Difference Between these Procedures?

All of the procedures performed in Colorado and throughout our U.S. Regenexx Procedure Network are same-day procedures. This means that the patient’s cells are harvested in the morning, isolated and processed, then re-injected into the patient’s injured area – all within a period of a few hours. The Regenexx-C Procedure, which is only performed at Regenexx Cayman, involves harvesting the cells on the patient’s first visit, growing them to larger numbers over approximately two weeks, testing the cells, then re-injecting the cells during the patient’s second visit.

Dr Chris Centeno explains the FDA’s stance on the Regenexx-C cultured stem cell procedure, which has not been performed in the United States since 2010 (currently offered by Regenexx Caymen):

[Disclaimer: The Regenexx® same-day procedures are performed in the United States. The Regenexx-C cultured stem cell procedure is only offered outside the U.S. through independently owned and operated medical services providers operating exclusively in countries that allow autologous cultured cells to be used through their local regulatory structure. These service providers are not part of nor affiliated with the Centeno-Schultz Clinic nor any U.S. Regenexx Network provider. The Regenexx-C procedure licensed by these entities is not approved by the U.S. FDA for use in the United States.]

Are the Regenexx procedures performed in the U.S., FDA-approved (-SD, -AD, -SCP, -PL-Disc)?

The Regenexx procedures performed in the United States are compliant with CFR 21 Part 1271 and fall under the same surgery exemption discussed in 1271.15 (b). Click the toggle above for full details.

Is a Stem Cell Procedure the same as PRP (Platelet Rich Plasma)?

No.  PRP is concentrating platelets in the blood, not stem cell therapy.  This is a more detailed discussion on the differences between PRP and stem cell therapy.  In addition, while PRP is one component of the therapy, we use a very different “Super Platelet Mix’ which we believe helps to produce many more stem cells.

We do offer the Regenexx-SCP procedure, which is a platelet procedure which is quite different from the bloody PRP available through commonly used bedside centrifuges. To see a patient infographic on these differences, see this link for general info on the Regenexx-SCP platelet procedure and this one for a comparison between SCP and bedside PRP machines.

Is this treatment the same as “same day” stem cell therapy where my bone marrow or stem cells are spun down in a centrifuge at the patient’s bedside?

No.  The Regenexx procedure involves isolating stem cells in a state of the art lab that’s part of a medical practice.  Unlike centrifuge machine procedures that produce a “one size fits all” solution, the Centeno-Schultz clinic in Colorado uses cell biologists to get to much higher stem cell numbers than are possible with a bedside machine. The network doctors who have learned these techniques also process their samples by hand in mini-labs.

What separates Regenexx-SD from other stem cell procedures currently being offered for orthopedic conditions?

Regenexx-SD is unique.  The biggest difference is the use of a “Super Platelet Mix.  To find out more, click here. In addition, there are other very significant differences between what we do and what’s offered as stem cell therapy. See the Regenexx Difference for more information.

How can I get a brochure on the Regenexx procedures?

Click here to download a Regenexx-SD brochure.

Click here to see an infographic about Regenexx-SD results, or here to see one on Regenexx-C results.

What basic science or published clinical data exists that show that these concentrated stem cells from bone marrow can help heal orthopedic injuries (i.e. Regenexx-SD procedure)?

For a PDF summary with active links of separate clinical studies (many listed below), click on the thumbnail image below.

mini orthopedic stem cell research thumb


-Bone marrow concentrate plus fat injections help knee arthritis function

Knee Surgery with Concentrated Bone Marrow Cells produces better Results than Knee Surgery Alone

Injectable MSCs helps cartilage repair scores in patients undergoing HTO surgery

Meniscus repair in the red-white zone

Micro fracture plus bone marrow concentrate for cartilage repair

-Knee osteochondral lesion-stem cell concentrate plus HA

-Concentrated bone marrow stem cells plus microfacture better than microfracture alone

Bone marrow concentrate plus microfracture stimulates sucessful cartilage repair in focal lesions…

-Mesenchymal stem cells plus hyaluronic acid used with knee micro fracture surgery

-Bone marrow concentrate plus bio scaffold for larger knee cartilage lesions

-Arthroscopic surgery plus bone marrow concentrate produces better cartilage repair on MRI than control images

-Cultured bone marrow stem cell injections produce better quality cartilage on follow-up MRIs

Cartilage Repair

-Assorted articles at National Library of Medicine on mesenchymal stem cells and cartilage repair (MSC’s are in the stem cell concentrate that is used with Regenexx-SD)

-One-step Bone Marrow-derived Cell Transplantation in Talar Osteochondral Lesions

-Knee arthritis treated with HTO and micro fracture plus stem cells

-Nice review article on clinical studies of cartilage repair using both bone marrow concentrates and cultured bone marrow stem cells


Osteonecrosis of the femoral head

Another study on AVN of the hip

One of the original studies on using bone marrow stem cells for AVN of the hip (1990s experience)

Hip osteoarthritis


-Nice review article on the use of bone marrow concentrate with platelets to repair ankle cartilage lesions

Building New Blood Vessels

Building new blood vessels with stem concentrates


-Bone marrow concentrate improves hip fracture healing

-Bone marrow concentrate improves sinus surgery implant survival rates

-Bone marrow concentrate helps non-unions fractures heal

Promoting spinal fusion

Fracture healing

-Fracture healing (pseudo-arthrosis)

Fracture non-union

Bone marow stem cell stimulate healing of non-healing fractures…


Bone marrow stem cells dramatically improve rotator cuff healing at 10 year follow-up

Marrow Nucleated Cells work as well as Cultured Cells for Tendon Repair

-Different model, same results as above

-Equine model


-Bone marrow nucleated cells promote PCL healing (animal model)

-Bone marrow nucleated cells help heal MCL ligaments (animal model)


-Cancer risk is not increased in a 12 year plus follow-up of patients treated with bone marrow concentrate for orthopedic conditions

What information have you collected that suggest these procedures work?

See all data published in peer reviewed medical journals on Regenexx procedures

In addition to peer reviewed publications, we also publish our treatment registry data online. See the most recent treatment registry data on Regenexx-SD for knee arthritis, hip arthritis analysis 1 and analysis 2 using different metrics, all shoulder patientsrotator cuff tear patientsankle arthritis, and hand/wrist arthritis. In addition, low back sciatica outcomes on the Regenexx-PL-Disc procedure. Pre-publication data and before/after MRI case studies can often be found on the Regenexx blog.

Can I get an overview of the research behind various types of orthopedic stem cell treatments?

Click on the infographic below:

Are these embryonic stem cells?

No, they are simply your own adult stem cells. We only use autologous (your own) cells.

Are umbilical cord stem cells better?

Cord stem cells are stem cells isolated from a baby’s umbilical cord. While they may be more biologically active because of their young age, recent research has suggested that they can also transmit genetic diseases that the baby may carry. Until these issues are further sorted out (likely with better genetic testing), we would advise against using any donor stem cells to treat non-life threatening disease. (cells from another person). This would include cord cells, embryonic stem cells, or someone else’s adult stem cells. To learn more about this topic, see this YouTube presentation produced by Dr. Centeno.

Are there different types of adult stem cells?

Yes, there are many types of adult stem cells. The most common is known as a hematopoetic stem cells (HSC-CD 34+). While these are easy to obtain from IV mobilized blood (where a special medicine is given to the patient first to push these cells out of the bone marrow) or bone marrow and are very plentiful. Outside of a handful of cardiac and vascular applications, they are not well studied as being effective in treating a broad range of diseases. Despite this, the vast majority of what you see being billed as “stem cells” from bone marrow (where the cells are injected the same day as collected) these are less useful cells. The type of adult stem cell that is most often seen in research as being associated with orthopedic tissue repair is a mesenchymal stem cell (MSC). MSCs can’t generally be harvested from blood. Fat tissue contains many MSCs, but these are distant cousins to the type obtained from bone marrow and aren’t as useful for orthopedic applications. For more more information on why stem cells from fat aren’t as useful as those from marrow to treat orthopedic injuries, click here. For an easy to understand patient infographic on why bone marrow stem cells are better than fat cells for orthopedic tissue repair, click here.

Are there different types of MSC’s?

Yes. For orthopedic applications, two main types of MSCs have been used, bone marrow derived and adipose (fat) derived. Bone marrow MSCs are taken via a needle through a bone marrow aspirate. The bone marrow aspiration procedure sounds like a big deal, but we are consistently told by patients that the procedure is very comfortable. The second type of MSC is derived from fat tissue (adipose). This can be obtained via liposuction. For orthopedic applications, fat derived MSCs consistently and dramatically under perform bone marrow derived cells. In studies of cartilage repair, bone repair, and soft-tissue repair, bone marrow derived MSCs are much more adept at these tasks. This makes sense, as they perform this function naturally (homologous) everyday. For example, if you break a bone, it’s these bone marrow MSCs that help mend that bone. In addition, for surgical micro fracture to repair small amounts of knee cartilage damage, it’s bone marrow MSC’s that are released to do that job.

Doesn’t fat (adipose tissue) have more stem cells than bone marrow?

Yes and No. First, many adipose stem cell clinics dramatically over-estimate the number of stem cells in their processed fat. This is a good hard core science review of the kits often used by physicians which over estimate these numbers. Basically, what physicians believe to be cells are actually small globs of fat tissue. Second, the proprietary Regenexx stem cell isolation method dramatically increases the number of stem cells isolated from bone marrow (based on our lab studies).

Still, on a weight to weight basis, fat can contain more mesenchymal stem cells than bone marrow, but the problem is that they just don’t work as well for orthopedic applications (click here for more information on this topic). In addition, in the Regenexx-AD knee stem cell procedure we offer the best of both worlds, bone marrow and fat.

For an easy to understand patient infographic on why bone marrow stem cells are better than fat cells for orthopedic tissue repair, click here.

Conditions Treated, Success Rates

What types of problems can be treated?

Fractures that have failed to heal, joint cartilage problems, partial tears of tendons, muscles, or ligaments, chronic bursitis, avascular necrosis of the bone, and lumbar disc bulges.

What body areas do you typically treat?

Knee, hip, shoulder, ankle, hand, foot, elbow and spine.

What are the most commonly treated conditions?

Toggle to view the most commonly treated conditions by body part


  • Avascular Necrosis
  • Osteonecrosis
  • Bursitis
  • Arthritis
  • Tendinopathy
  • Labral / labrum tear


  • Rotator cuff tears
  • Arthritis of the shoulder joint
  • Thoracic outlet syndrome
  • Labral tears or degeneration
  • Rotator cuff tendonitis
  • AC Joint Separation
  • Recurrent shoulder dislocations

Hand and Wrist

  • Hand Arthritis
  • Instability
  • TFCC tear
  • Carpal tunnel syndrome
  • Trigger finger

Back and Neck

  • Lumbar facet injury
  • Herniated or bulging disc
  • Radiculopathy (pinched nerve)
  • SI Joint Syndrome
  • Cervical instability
  • Cervical facet injury
  • Neck, back or rib instability


  • Arthritis
  • Patellofemoral Syndrome/Chondomalacia
  • Pes anersine bursitis
  • Baker’s cyst
  • Patellar tendonitis
  • Meniscus tear
  • MCL sprain or tear
  • ACL sprain or tear
  • PCL sprain or tear
  • LCL sprain or tear
  • Instability
  • Biceps Femoris Insertional Tendinopathy
  • Hamstrings Tendinopathy

Ankle and Foot

  • Arthritis
  • Ankle Instability
  • Peroneal tendon tear or split
  • Ligament sprain or tear
  • Sub-talar arthritis or instability
  • Tarsal tunnel syndrome
  • Plantar fasciitis
  • Bunions


  • Arthritis
  • Instability
  • Tennis Elbow or Golfer’s Elbow
  • Nerve entrapment (ulnar nerve)

Do you treat spinal cord injury?

Not at this time.

Do you treat any other problems outside of bone, tendon, muscle, joint, or ligament?

Not at this time.

Do you treat heart or vascular problems?

Not at this time.

What is the success rate? How many people respond? What is the cure rate?

This depends quite a bit on the severity of the disease.  We are constantly publishing case reports on our blog (often with before and after MRI images) which can usually be found at  In addition, the blog will also feature scientific publications as they are published.

Click here for a list of our scientific publications

-Click here for an easy to understand patient infographic the Regenexx-SD (same day) procedure results.

-Click here for an Infographic comparing Regenexx-SD and Hip and Knee Replacement outcomes…

-Click here to see one on Regenexx-C results

-Click here to read about patient reports on:

-Knee, HipShoulder and Rotator CuffBack and DiscAnkle and Foot, Hand and Thumb, Avascular Necrosis.

 Have you performed randomized controlled trials to test your procedure?

None have yet been completed, but we have three underway. The first involves rotator cuff tears, the second involves knee meniscus tears, and the third sciatica. For info on these trials, please contact us at

Does the Regenexx procedure always work?

NO. All medical and surgical procedures have a success rate. This procedure is no different. We do see patients who do not respond. Please take a minute to review a more detailed discussion on this topic by clicking here. In addition, we have featured patient treatment failures on the blog.

How many procedures have you performed?

As of February 2015 there have been more than 16,000 Regenexx procedures performed. We treated our first patients in 2005.

Marrow Aspirate

Is a bone marrow aspirate painful?

Patients often confuse a bone marrow aspirate with a more involved and more painful bone marrow biopsy. We only perform the less involved and much more comfortable bone marrow aspirate. Because we extensively numb the area, about 8 in 10 patients say that the marrow draw is very comfortable and would do it again. For more info on this topic, see

What about the patients who thought the marrow aspirate was painful?

If you have a history of chronic low back pain, more discomfort can be expected. In that case, the doctor may offer you an epidural injection to better numb the area.

How long does a marrow aspirate take?

20-40 minutes

How is a marrow aspirate performed?

The skin and tissues are numbed, then a needle is used to draw a whole marrow aspirate and this is sent to the lab.

Do you take marrow aspirate from more than one site?

One skin site on each side will be numbed and three samples are taken from each of those sites.

Isn’t it a lot safer to take fat via liposuction than a bone marrow aspirate?

No, an analysis of the published research shows that liposuction is more risky than a bone marrow aspirate.

What if I have anemia?

If your hematocrit is below 30 or your hemoglobin is below 10, we may not be able to perform the procedure. If your hematocrit is between 30-36 or hemoglobin below 12, we may try to limit the IV blood or marrow draw amounts and will have you follow-up with your family doctor.

Are there weight limits for the marrow aspirate for blood draw?

If you are under 110 pounds in weight, the doctor will likely decide to take less marrow or blood.

What if I have a blood clotting disorder?

If your clotting times are normalized by taking clotting factors, then there should be no problem performing the procedure.

What if I take Coumadin, Plavix, or other blood thinners?

We generally recommend that you stop these before the procedure. For example, if you take Coumadin, you need to have the OK of your family doctor or cardiologist to come off this drug and an INR (blood clotting test) that is in the normal range before pursuing this procedure. If you take other blood thinners such as Plavix, you should be off this drug for 72 hours prior to the procedure. Your family doctor or cardiologist may also need to be consulted to ensure that it’s safe to come off of this medication. If you take a daily baby aspirin, then you need to come off this one week before the procedure.

Blood Draw

How much blood will you take from my vein?

A total of 50-200 cc may be drawn (about a few teaspoons less than 1/2 a pint).  Less may be taken if you are under 110 pounds.  See above. It’s also possible that more blood might be drawn if needed.

Why do you need to draw blood from a vein?

The growth factors that we use to grow your stem cells are contained in your blood platelets.

Processing Stem Cells

What happens to the stem cells after you take them out?

The cells are isolated in the lab using a proprietary separation technique. For the same day procedure, this isolated stem cell fraction is placed right back into the body.

The Procedure

How painful is the procedure for implanting stem cells?

About as painful as a usual shot in a doctor’s office.

How do you know where to place the cells?

We use real time x-ray known as fluoroscopy or musculoskeletal ultrasound. Your MRI images are used to help plan that injection.


When can I expect to feel better?

The results should become apparent over 1-3 months, but sometimes can take as long as 6-9 months.

Will I need a second procedure?

Some of our patients will require a second or even third procedure. Our usual protocol involves 1-3 injection cycles. Most patients get a single procedure.

Should I take specific supplements after my procedure?

Yes, we have developed our own supplement based on lab tests with human mesenchymal stem cells and their response to various nutritional supplements. Click here for more info.

When can I return to normal activity?

This depends on the type of procedure. However, all of our procedures are designed to promote as much early activity as possible. Here is a general guide:
Bone healing procedure (for fracture non-union or avascular necrosis): You must be off the area on crutches until the pain from the procedure subsides. You can then move toward slowing increasing activities over the next few weeks. Total time off the area for most patients is 1-3 weeks with normal activities at about 6 weeks. The only exception is when there is an existing rod or plate stabilizing the fracture site, in these cases you will be allowed more activity more quickly.

Joint procedure. If there is more minimal cartilage loss, low impact activities would be encouraged immediately after the procedure. Full high impact activities would be expected at 4-6 weeks.

Partial tendon/ligament/muscle tear: Low impact activities would be encouraged immediately after the procedure. Full high impact activities would be expected at 4-6 weeks.

Is physical therapy needed after the procedure?

In general, we always try to look at more than one injured part. As a result, it’s very likely we will recommend other types of conservative care to restore normal biomechanics. This might include physical therapy, different types of myofascial release, or specific home exercises.

Is there anything else that you need me to do to help the cells?

Yes, we ask that all patients either use a home infra-red unit or another type of ultrasound unit to help with cell growth. The infra-red unit is available through Active Forever

Insurance Coverage

Why doesn’t insurance cover this procedure?

NO. The procedure is too new to be covered yet by insurance.

Will insurance cover the initial evaluation?

If we are on your insurance network we will bill your carrier. If not, then there will be a consultation fee for the initial face to face consult.

Getting a Review of Films with a Clinic Doctor

How can the doctor determine if I’m a candidate for the procedure?

The doctor can look at your films, history, and speak to you on the phone about if he or she believes this may help your problem. It’s important to note that this is not the formation of a traditional doctor – patient relationship until you see the doctor. Rather, this is just an opportunity for the doctor to determine if you’re a reasonable candidate for the procedure and for you to ask addition questions.
Realize that we currently place about 1/4 of the patients we see as GOOD candidates for the procedure, 1/2 as FAIR candidates, and 1/4 as POOR candidates. For more info on this, see

How much will the review of my imaging / films cost?

The charge is $200 for 15-30 minutes with the doctor. If you are determined to be a qualified candidate for the Regenexx-SD or Regenexx-AD procedures, this fee will be applied to the cost of the treatment. The fee is not applied to the cost of treatment for our platelet procedures: Regenexx-PL, Regenexx PL-Disc, or Regenexx-SCP.

How can the doctor look at my imaging / films?

The doctors prefer CD’s and not hard copies of actual films. These days, most imaging centers can easily and inexpensively burn a CD with the digital copies of your films. These can be sent to Regenerative Sciences, Inc at 403 Summit Blvd. Suite 201, Broomfield, CO 80020. We also provide a way to upload your imaging.

How do I set up a review of my imaging / films?

Please complete the Regenexx Candidate Form and you will receive complete instructions on the review process.


Using the HHS OHRP guidelines for complications reporting, our complications to date have been in the mild to moderate category and rare. This means that either the complication (like transient swelling) required no medical treatment (Mild), or if it did require medical treatment, the treatment was simple (Moderate-like a patient who failed the procedure who ultimately decided to get the knee replacement that he or she was planning before the procedure). We have published the world’s largest (to date) safety and complications tracking study of adult stem cell use in patients. This study did not show any serious stem cell related complications and it did not show that any patient developed a stem cell related cancer. In addition, our most recent safety paper was named the best of it’s type by a meta-analysis that appeared in the prestigious medical journal, Osteoarthritis and Cartilage. 


Can I find other doctors outside of Colorado who use your methods?

We are training other doctors in the technique and building a provider network. Like any new technique, the medical community takes some time to adopt the procedure. To see if there is a doctor in your area, click here.

How do the stem cells know what type of tissue to grow into?

Based on the research in this area, local cell type, pressure, and chemical environment also help the cells to determine which type of cells will be formed.

How will my stem cells know when to stop growing?

Unlike embryonic stem cells, adult stem cells do not generally keep growing, even in culture. For example, most patients whose stem cells we grow to bigger numbers in the lab will lose their ability for continued cell growth after just a few weeks. In addition, the same body signals that would tell these cells to stop growing in healing a normal fracture or ligament tear are still present in your body.

Can an adult stem cell re-implant cause cancer?

The basic science on adult stem cells shows that if the cells are kept in culture for short periods, that there is no risk of the cells becoming cancerous. We have published the world’s largest (to date) safety and complications tracking study of adult stem cell use in patients. This study did not show any serious stem cell related complications and it did not show that any patient developed a stem cell related cancer. Finally, we maintain an extensive complications tracking database with patient contacts at specified times. We have seen no evidence of significant complications at these re-implant sites. We also work with an outside lab for quality to clear each patient’s cells before they are used in treatment as an additional safety check.

What has been the longest time period of observation that leads you to conclude there is no tumor risks?

Approximately 10 years.

What triggers the cessation of cell growth during regeneration? Has regeneration ever surpassed expected optimal growth?

Mesenchymal stem cells will stop proliferating when they physically contact each other (otherwise known in cell culture lingo as “confluence”). Culturing these cells, it becomes obvious that once they reach that point, they refuse to continue to grow (proliferate). This is because they are repair cells and when an area in need of repair is fully covered, they get the signal to stop growing. In the appr0ximately 60 patients where we have ongoing MRI surveillance of the re-implant sites, there has been no evidence of overgrowth where the regeneration has surpassed “expected optimal growth”.

Do mesenchymal cells stay localized to the injection site…is there any risk of them traveling throughout the body?

MSC’s do stay local at the injection site across multiple studies. This is likely linked to the fact that they generally do not circulate in the blood stream like other adult stem cell types and are primarily found resident in the tissues they serve.


Why can’t I be on certain medications during the procedure?

Certain types of medications will negatively impact the stem cells. In addition, we generally see that many prescription medications will reduce stem cell number.

Are there any medications or supplements I can take that will increase the activity or healing abilities of my stem cells?

We produced the Regenexx Advanced Stem Cell Support Formula to support healthy stem cell function and cartilage production. Learn more or buy the supplement here.

Stem Cell Lab(s)

What type of lab do you use to process the stem cells?

Our lab is an extension of our medical practice. We only process cells in ISO-5 hoods (biologic safety cabinets) and these hoods are located in a lab with particle counts consistent with ISO-6.

Who checks to make sure that you are following these guidelines?

We use nationally known lab accreditation companies. We periodically audit the lab and make any changes recommended by auditor.

Are you licensed by the state?

Colorado has no tissue bank licensure. However, recently New York state asserted that we needed a New York tissue banking license to treat NY patients. While we disagreed with the general assertion that NY can regulate medical activities in Colorado, we did apply for such a license and did receive a license, which can be seen here.