The Most Advanced Orthopedic Stem Cell Procedures in the World - Regenexx®

How Can We Claim to Offer the Most Advanced Orthopedic Stem Cell & Platelet Procedures in the World?

Here are the details in more depth. Get's not easy reading, but we hope you will find it valuable.

Why Regenexx is Superior to Other Stem Cell Solutions

How can Regenexx claim that it’s the most advanced and best-researched orthopedic stem cell therapy in the world? After all, if you cruise the Internet, you’ll find any number of clinics, all proclaiming that they’re the “best” or the “greatest” or “experts.” However, if you look “under the hood” of any of these clinics and then compare that to Regenexx, you’ll see it’s like comparing a subcompact car to a Ferrari.

The doctors who founded Regenexx (Christopher Centeno and John Schultz) were the first in the U.S. to begin to use stem cells to treat orthopedic conditions. Since then, we have created a network of highly select and highly trained physicians who claim to be performing the most advanced and best-researched stem cell procedures in the U.S. and the world. The information below supports these claims. It is technical in nature and is written for those who really want to understand just how superior Regenexx is when compared to competitive solutions.

How Regenexx Compares to the State of Current Sophistication and Research

At issue is the use of same-day stem cells (bone marrow concentrate, or BMC) and platelet rich plasma (PRP) to treat orthopedic conditions via image-guided injection-based treatments.

What is Regenexx?

We are a group of 30-plus US medical practices that use the same BMC and PRP treatment protocols. We all fund a university-style clinical-research and lab-research facility headquartered in Colorado. Given that much of the data reported below has been gathered via our registry or university-style lab, a short discussion about both is warranted.

What is the Regenexx registry?

We use university-based, open-source clinical-research organization software (Clinovo) and have four full-time employees who track outcomes and complications. Preoperative data is collected on all BMC-treated patients via validated pain/functional questionnaires. The registry sends questionnaires at 1, 3, 6, and 12 months following treatment and then annually on an ongoing basis. The software sends automated e-mails two times, and if the patient doesn’t respond, then up to three phone calls are initiated. If the patient fails to respond, that outcome end point is lost to follow-up and the patient is reacquired at the next time point. This registry has now been moved into a 501(c)(3) nonprofit—the Interventional Orthopedics Foundation.

What is the Regenexx Research Lab?

colorado regenexx labIn Colorado we have three full-time scientists and a lab equipped with normoxic and hypoxic incubation, flow cytometry, fluorescence-activated cell sorting, inversion microscopy, fluorescent microscopy, PCR LightCycler (a rapid high-throughput, plate-based, real-time PCR amplification and detection instrument), ELISA, multiplex microarray ELISA, -80 and -150 cryostorage, and other technologies. (See images below of some of these technologies.)

We conduct basic in-vitro experiments to improve our procedures at this privately funded lab. Most university-level stem cell labs do not have some of these capabilities, such as flow cytometry and cell sorting, on site. In addition, neither do many companies manufacturing automated bedside centrifuges. As far as we know, this is the most sophisticated lab facility dedicated to orthopedic stem cell research anywhere in the U.S.

What does all of this compare to? Right now, physicians offering FDA-compliant bone-marrow-based stem cell therapies fall into one of two categories: they use an automated bedside centrifuge or they use an in-house laminar flow hood to process samples on site. For both types of practices, there is no clinical or in-vitro research being conducted to continuously improve the procedures. Both types of practices use simple technology that’s fixed in what it can produce. While I’ll discuss further the issues this causes and how the Regenexx group practice has pushed beyond these technologies, it’s important to realize that when we claim to be more advanced, “top,” “world’s leading,” and better researched, these claims are supported by the world’s largest clinical registry of its kind and one of the most sophisticated private-practice-based lab-research operations in the world.

The substantiation for these claims can be broken into key components. To understand this, it’s helpful to review how autologous bone marrow concentrate (meaning using the patient’s own bone marrow) injections are used to treat orthopedic conditions.

This process can be further broken down into the following steps:

  • The bone marrow aspiration (BMA)
  • The processing of the bone marrow aspirate sample
  • The reinjection
  • Ongoing research

After reviewing each step of the process, I will then focus on how Regenexx is superior to what other physicians are offering.

The Bone Marrow Aspiration

Regenexx as a group medical practice, as of the spring of 2016, has performed approximately 4,000 bone marrow aspirations (BMAs) since 2005 and uses only advanced techniques to perform this procedure. First, what is a BMA? Second, why is it important to quantify cell dose, and how does that intersect with how the BMA is performed? Finally, why is it critical to perform the procedure using imaging guidance? As you will see, how we approach a BMA makes us the consistently most advanced purveyors of the BMA technique.

A bone marrow aspiration is performed by using a trocar (sharp-tipped instrument) to cannulate the bone, commonly in the pelvis. This simply provides a small tunnel into the bone so the liquid portion of the bone marrow (termed an aspirate) can then be removed via syringe. The typical way this procedure is performed is to draw a high volume (60 ml) of aspirate from a single site. This is quite different from how it’s performed within the Regenexx group medical practice, and as you’ll see, our own research and that published by others has shown that this is not the best way to maximize stem cell yield from the BMA. At Regenexx our technique involves cannulating multiple sites with lower-volume draws.

stem cell dosing knee arthritisFirst, how important is it to maximize mesenchymal stem cell (MSC) content in a BMA? Mesenchymal stem cells are found in the bone marrow and can naturally transform into many tissues including bone, cartilage, and fibrous tissue. In 2015 we published a dosing paper that used total nucleated cell count (TNCC) as a proxy for MSC yield in patients undergoing bone marrow concentrate (BMC) treatment for knee osteoarthritis (OA). This was due to earlier published research showing that a TNCC directly related to MSC content in BMC samples. In that registry-based paper, we concluded that there was a relationship between decreased pain and a TNCC count of greater than 400M injected cells. (See the receiver operating characteristics curve above.)[KLA1]

Others have reported similar results in different applications. As an example, a recent small case series published on the use of intradiscal treatment with BMC found a direct correlation between colony-forming units (an indirect measure of MSC content) and outcome. In addition, the efficacy of BMC when used for bone-healing applications, such as for nonunion and osteonecrosis, is also dependent on MSC dose. Hence, the MSC content of BMC, or proxies for it, is directly related to clinical outcome in a classic direct dose-response relationship.

Based on this dose-response relationship, one of the important differentiators between Regenexx and everyone else performing this technique becomes apparent. Ninety-nine percent of the physicians who use BMC have no ability to count the cell number they’re harvesting. This is because the automated bedside centrifuges don’t provide this count, and the cell-counting devices that are available require trained lab staff and validation, which aren’t possible in the average practice. However, all Regenexx group practices count the number of cells available to determine dose.

The current state of the art at practices worldwide that use BMC is to inject an unknown dose. There is obviously no other area of medicine where a substance is injected into the body at an unknown dose or concentration.

percentage correct stem cell dose for knee OAIf dose is important and only Regenexx physicians routinely determine dose, how important is it to maximize MSC content (dose) during the BMA technique? If we use the data we have collected on the minimum knee OA dose (400M TNCC) and the data we have amassed in counting common total nucleated cell content in BMC, several issues emerge. For example, our most common application in knee OA is a patient with bilateral disease who wants both knees treated at the same visit. However, using the data that we have collected, to the right is the percentage of patients (“%” columns) who can obtain a TNCC of 800M cells (400M per knee) by sex.

Hence, the percentage of patients who can achieve 800M cells and comfortably treat their bilateral knees is small. Given that this is a common request and almost no clinics using BMC have the ability to count cells, many are likely treating this condition with far too few cells. At the very least, this illustrates the need to maximize the number of MSCs that can be obtained via a BMA.

stem cell yield by bone marrow volumeWe have known, based on the peer-reviewed literature since the late ’90s, that cannulating many bone marrow sites and aspirating small volumes increases MSC yield over a single site cannulated to withdraw a larger volume (see article 1, article 2, article 3). As discussed above, our experience in speaking with physicians nationally and training physicians in this procedure, through a 501(c)(3) nonprofit, has shown that most physicians are only cannulating one site and withdrawing a large BMA volume, reducing MSC yield. The two graphs above were generated by our team based on the MSC yields of left- and right-sided patient draws (n=5). The first compares the MSC yield from a low-volume BMA (3.5–6.5 ml) to a higher-volume draw (9.5–11 ml). The second compares the MSC content of a BMA (30 cc) drawn from one site versus the same volume drawn from many sites (3). Both data sets show improved MSC yields from the lower volume and higher number of BMA sites cannulated.

bma siteWhile the typical BMA technique is performed blind, all of the members of our national group Regenexx practice use imaging guidance to perform BMAs. Why is this critical? To the left is a cross section of the PSIS showing a thick area that when cannulated will result in a true bone marrow aspiration (i.e., the trocar tip will be seated in the marrow space—yellow arrow). However, if an adjacent paper-thin area of the marrow is cannulated, it’s highly unlikely to result in the aspiration of marrow (i.e., the trocar tip has gone through and through the pelvis and is not in the marrow space—red arrow).

Given that our national team is in constant communication with hundreds of physicians who are prospective candidates to join our group practice, and elsewhere these things are most commonly not done, these are the differentiators for “most advanced” in the area of BMA:

All Regenexx doctors perform BMAs in the way the peer-reviewed literature and the internal research performed by the practice shows maximizes MSC yield. All Regenexx doctors count cells and know dose. All Regenexx doctors use imaging guidance to harvest cells

The Processing of the Bone Marrow Aspirate Sample

Almost all physicians who use bone marrow concentrate utilize automated bedside centrifuges to process the bone marrow aspirate sample. The goal of this processing is to concentrate the stem-cell-containing fraction of the aspirate. The dose discussion above is one of the reasons that many physicians and scientists believe this concentration is needed.

bone marrow concentrateAll automated machines use the same basic process to concentrate bone marrow—they capture the “buffy coat” with varying levels of efficiency. This is the small, gray in color, middle layer that appears after the BMC has been centrifuged—the traditional source of MSCs derived from the bone marrow. Given changes in hydration and hematocrit, it’s not hard to see that this layer may appear at differing heights in different patients. Most of the automated bedside machines in use today account for this variation among patients by taking a large cut of sample above and below the buffy coat, reducing the total BMA volume from 60 cc to approximately 10 cc. Given that the size of the buffy coat in a 60 ml sample is usually 1–2 cc, this creates a concentration problem (i.e., 1–2 cc of active ingredient diluted in 10 cc).

When the Regenexx group medical practice first began, our focus was also on capturing this layer. However, manually processing this layer in a laminar flow hood in a medical practice resulted in much higher concentrations as the usual dilution we could accomplish was 1–2 ml of active buffy coat in approximately 3 ml of total BMC. Hence, the first version of our process was more advanced than automated bedside units because it produced an injectate with 3–4 times the concentration of the buffy-coat active ingredient over automated bedside systems.

MSC content LLDIn 2012, our group medical practice asked the question of whether it was possible to increase MSC levels even higher. We were able to find a second source of MSCs in BMA that was being discarded. This is a proprietary discovery that is the subject of a patent application, so I will describe it with that in mind.

The chart entitled “PO Counts” is a comparison of the MSC content of the two layers with the traditional buffy-coat (BC) isolation versus the new source (we call this LLD). As you can see, the differences in the number of MSCs obtained via colony formation after plating the buffy coat versus the LLD is stark. In all seven patients tested, LLD MSC content significantly beats the buffy coat.

mRNA levels LLDIn addition, other studies performed in our lab found that the MSCs in the LLD were faster growing and more chondrogenic (more capable of cartilage repair) than those found in the buffy coat. For example, the graph entitled “Day 8 mRNA Levels” shows that the gene expression panel associated with chondrogenesis (cartilage development) is hugely upregulated in LLD cells versus buffy-coat cells.

When we added these two fractions together, we produced a BMC that had an MSC content that was reliably 5–20 times higher than what could be obtained via automated bedside centrifuges. In addition, given the orthopedic-injury focus of the group medical practice, the fact that MSCs from the LLD are present is important to us. However, we also sought additional validation that this new processing technique would translate into better clinical success. sd plus knee arthritisThe graph entitled, “Second Generation Regenexx-SD Procedure” represents a prospective registry comparison trial between the first-generation processing and the newer second-generation technique (BC+LLD).

In treating knee osteoarthritis patients, Lower Extremity Functional Scale (LEFS, functional improvement), Numeric Pain Rating Scale (pain improvement), and self-reported percentage improvement (% improvement) were all significantly better with an injection of the cells from the new processing technique containing more MSCs and a second fraction that was more chondrogenic.

How Regenexx PRP Is Different

Another common practice with the use of bone marrow concentration (BMC) to treat osteoarthritis is to add platelet rich plasma (PRP) to the injection. The goal of adding PRP to BMC is that as the platelets degranulate, they will release growth factors helpful to MSCs. Regenexx has also conducted its own in-vitro research to optimize this process. We first conducted experiments looking at the differences between red/white blood-cell-rich PRP (RBC+/WBC+) versus red/white blood-cell-poor PRP (RBC-/WBC-).

The graph below contains the results of an experiment that looked at the ability of the two different types of PRP (“SCP”=RBC-/WBC-, and “Bloody PRP”=RBC+/WBC+). The differences were stark, with the proxy for mesenchymal stem cell (MSC) count (CFUs, or colony-forming units) used here showing dramatically better proliferation (i.e., more stimulation of MSCs) with “SCP.” aaaThis is an issue, as most physicians use RBC+/WBC+ PRP hoping it will stimulate MSCs. As a result of this internal data, we thus concluded that we would use the very different RBC-/WBC-.

The other variable in using PRP to support MSC growth in BMC is platelet concentration. Most bedside units that produce PRP can only muster a concentration of 3–7 times over baseline. Is this enough? We have also tested this in-vitro.

bbbThe graph above shows our internal data where we tested various concentrations of RBC-/WBC- PRP preparations against MSC proliferation in culture, finding a direct dose-response between concentrations much higher than bedside machines can produce. Hence, using a 14–20 times concentration of RBC-/WBC- PRP became part of the Regenexx protocol.

How Regenexx Uses a Unique Blood Product—Platelet Lysate

There’s another unique component to the procedures used by our medical group not used by others—platelet lysate (PL). PL is created by the lysis of platelet rich plasma, which releases growth factors (GFs) contained in platelets into the serum. The difference is that while platelets in PRP slowly degranulate their GFs over approximately one week, platelet lysate has all of these GFs immediately available. Hence, PRP is rarely used to provide GFs to culture MSCs in-vitro, while PL is commonly used for this purpose. Regrettably, there is no automated bedside centrifuge that can be purchased that creates PL; hence, its clinical use is limited to those who have established small office-based lab facilities.

dddJust as our group medical practice has extensively studied the optimization of BMC and PRP via MSC assays, or testing, we have also studied PL. First, we studied many different methods to lyse platelets as different methods provide different levels of lysis efficiency. The graph entitled “Platelet Counts in Lysates” shows the level of lysis achieved in four different methods. Based on this, we settled on the best method to create PL.

We next studied the growth factor content produced by the various lysis methods. The graphs below represent internal data on ELISAs that demonstrate GF levels in the first (PL) and second (PLM) generations.

GF content prpThese increased GF levels tie directly to increased MSC proliferation. The inversion microscopy images above are from an in-vitro, in-house study looking at proliferation of MSCs when exposed to PL (generation one) and PLM (generation two). GF invitro msc growth with platelet lysateThe MSC counts in PL showed less proliferation than those cultured in PLM. This is apparent in the pictures, showing that MSCs are sparsely populated in the monolayer culture flask on top (PL) and densely populated in the one on the bottom (PLM).

In summary, these are the differentiators between the automated bedside centrifuges used by most practices and the process used by Regenexx that support our claims:

Manual processing allows much higher concentrations of the buffy-coat active ingredient.
Adding in LLD cells allows still higher concentrations of MSCs, and this, based on our internal research, has shown better clinical outcomes in our most commonly treated patient type (knee OA).
Using RBC-/WBC- PRP at very high concentrations allows for better in-vitro evidence of MSC support than lower-concentration RBC+/WBC+ PRP. Using a proprietary high-growth-factor platelet lysate shows significantly improved in-vitro MSC proliferation.

The Reinjection

shoulder injection proceduresMost injections performed in orthopedic practices are blind without guidance. This is despite research showing that nonguided injections of the knee, for example, have a significant intra-articular miss rate (ref). In addition, even when practices adopt ultrasound or fluoroscopy guidance, the injection procedures are usually of low sophistication level. As an example, to be certified by our medical group practice in Shoulder, these are the procedures that the physician must demonstrate mastery in via a cadaver lab after extensive didactic education. Note that for the shoulder alone, there are 12 separate imaging-guided-injection procedures that must be demonstrated to an instructor in a cadaver course.

image guided knee injectionsThe injection list for the knee is also extensive. It also contains 12 imaging-guided procedures.

Given that we have physicians who apply to be a part of our group medical practice, we use these core-skills lists to determine if a physician has the base training to be able to perform our procedures. The majority of physicians who report their existing skills back to us don’t have the ability to perform these procedures. However, for a provider in the Regenexx group medical practice to advertise that he or she has these skills in a given area, the provider needs to demonstrate to an instructor competency in the entire array of imaging-guided procedures by body area during a cadaver course. As a result, we accept only about 10% or less of the medical providers who want to join our group.

How does this compare to the average provider offering stem cells and PRP? As discussed, most don’t use guidance at all, instead performing blind procedures. While some do use ultrasound guidance and a few use fluoroscopy (real-time X-ray imaging), almost none have both technologies available. In addition, even when these imaging-guidance technologies are available, the vast majority of providers only know how to perform the simple intra-articular injections on these lists. Very, very few understand how to perform the more advanced procedures.

As an example, the provider might understand how to inject a knee and get the cells inside the joint using ultrasound. However, he or she doesn’t know how to inject the meniscus or the ligaments (ACL, PCL, MCL, or LCL). Or the provider might know how to inject the shoulder and get the cells generally inside the joint, but can’t inject the superior labrum or rotator cuff.

How One Procedure out of Twelve Required Knee-Injection Skills Supports the Thesis of “Most Advanced”

acl ligament stem cellsLet’s move from a 30,000-foot overview of the skills needed to be in our group practice to a focused close-up view on one specific knee procedure on that list. I’ll first review the data we have published and are collecting on this technique and then an exemplar of the results. Finally, I’ll discuss the specifics of this method.

One of the indications where we have seen great success is in knee anterior cruciate ligament (ACL) tears. As an example, our recently published case series showed MRI evidence of the ability of our injection-based bone marrow concentrate (BMC) protocol pioneered by our practice to heal partial and complete nonretracted ACL tears.

This study used computer-based imaging analysis of before and after MRIs. The ACL images were analyzed based on the metrics that indicate a healthy low-signal ligament.

Below is an MRI exemplar of the results of this procedure. This is a patient with a full-thickness ACL tear who was told she needed ACL reconstruction, but she opted for precise placement of BMC into the remaining disrupted ACL fibers. On the left is the MRI immediately prior to the injection, and on the right is the MRI three months after the injection. The before image was read by the radiologist as a complete ACL tear, and the after image as a “normal ACL.”


acl mri stem cells


We are now readying a second, larger case series for publication and have self-funded a randomized controlled trial (RCT). Note that no physician who wanted to join our network (who would likely be a typical cross section of US physicians performing BMC and PRP injections) knew how to perform this procedure before joining the network. Let’s delve deeper into that technique.

In the case of the ACL procedure pioneered by our medical group, BMC is seeded into the ACL at the origin and insertion of each bundle (the two bundles are posterolateral and anteromedial and help stabilize the knee joint by tightening or relaxing depending on whether the knee is flexed or extended) under C-arm fluoroscopy. This requires significant technical skill and training. This is not a procedure that is taught in residency programs, courses, or private practices. It is only used currently by physicians trained by our group practice. We have many such procedures.

Hence, in support of the “most advanced” as far as cell placement we have the following:

Injections are only performed with guidance versus the more common blind variety.

The vast majority of physicians do not have these skills as demonstrated by our own data.

Many of the procedures we offer are unique to our medical group and have been pioneered by us and are not widely taught.

Ongoing Research

Our group practice has been involved in ongoing research to improve our procedures. This can be broken down to the following:

  • Registry data collection and published data sets
  • Ongoing clinical and lab research
  • Registry Data Collection

We have collected outcome and complications data in a registry since 2005. This effort has cost millions of dollars to administer. As of today’s date (March of 2016), we are tracking more than 4,000 stem cell treated patients. In 2015, the resigstry was turned over to a 501(c)(3) nonprofit—the Interventional Orthopedics Foundation (IOF). The IOF is now running the day-to-day operations of the registry.

The data from this registry has been the subject of many different papers published in the peer-reviewed literature.

An extensive list and links to these papers can be found on our Stem Cell Research Page.

Ongoing Clinical and Lab Research


Our practice has self-funded three randomized controlled trials (RCTs)—knee OA, knee ACL, and shoulder rotator cuff tear. The knee OA RCT using our protocol will be finished this year, and the other two are ongoing. As an example, early data from the shoulder RCT is above.

On the lab-research front, we continue to innovate. For example, our group medical practice is using its resources to investigate the microenvironment (ME) of knee OA patients. We are using multiplex microarray ELISA to measure 25 growth factors and cytokines in patients undergoing our BMC procedure. The goal is to tie this ME to outcome (i.e., do patients with a toxic and proinflammatory ME have a poorer outcome than other patients who have a better ME?). The second is a long-term investigation to determine if controlling the ME in select patients will allow us to improve outcome. We know of no other medical practice in the U.S. or worldwide that is working at this sophistication level trying to optimize BMC therapies for knee OA.

Hence, in support of the claims for orthopedic BMC-treated patients, as far as research we have the following:

  • The world’s largest registry tracking patient outcomes and complications
  • The most research based on patient sample numbers published out of this registry
  • Ongoing research projects that are more sophisticated than other group’s using BMC


The Regenexx medical group doesn’t make claims lightly. Unlike a medical practice that buys an automated bedside centrifuge and takes a weekend course on how to perform a BMA and use BMC or PRP, as the evidence shows, we are quite different. Everything from the back-end lab research to the way BMA is acquired, processed, dosed, and reinjected is more advanced than what is being commonly performed by other physicians.

Can a stem cell procedure help me? To find out if you might be a candidate for a Regenexx stem cell procedure, complete our Regenexx Procedure Candidate Form online.

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