A human mesenchymal stem cell (MSC). Magnification 3000x
A human mesenchymal stem cell (MSC). MSCs are multipotent stromal (connective tissue) cells that can differentiate into a variety of cell types, including cartilage, ligament, tendon and muscle cells. Magnification 3000x

Biocellular (Stem Cell–Rich) Prolotherapy

This is the most advanced and aggressive form of Prolotherapy. It is used either when other forms of Prolotherapy have stopped working, or as a first procedure when a condition is severe. Adult stem cells exist within our own bodies; we are born with them and these cells exist to help with repair when needed. Since the tissue used in this type of Prolotherapy is taken from ones own body it is called “autologous” (auto meaning “self”). The two main tissue sources used in this type of Prolotherapy are either fat (medical term “adipose”), or bone marrow, and the term “Biocellular” is an umbrella term which covers either tissue source. This type of Prolotherapy is often called “Stem Cell-Rich” because these tissues are rich in adult stem cells. Biocellular Prolotherapy is especially well suited for sports injuries because of its tendency to encourage repair using new, normal tissue rather than weaker scar tissue.[1]

Biocellular Basics

All the tissues in the body are made up of cells. Any particular kind of cell—such as skin cells, muscle cells, ligament or cartilage cells—are referred to as being “specialized” because they have already developed into an established, distinct type of cell. However, we also have cells in our bodies that are partially specialized; that is, they have developed to a certain point only, and then stop there, waiting until they are needed for repair, at which point they have the ability to “stem” into the specific kind of cell needed. These partially specialized cells within our own bodies are called “adult” stem cells, and it is believed that their primary role is to maintain and repair the tissue in which they are found. [2]

The Mesenchymal Stem Cell

A Mesenchymal Stem Cell can change into differnt types of tissue.

The adult stem cell that interests the prolotherapist is the mesenchymal stem cell (“MSC”). This is the cell type from which the musculoskeletal system develops. The MSC is partially specialized to the point where it can become ligament, tendon, cartilage, muscle, fat, or bone, but it does not commit to a specific cell type until the need arises. For this reason, MSC's are called “multi-potential” or “multipotent,” since there are multiple potential directions these cells can develop. The process of becoming more specialized into a needed cell type is called “differentiation” (from Latin for “to develop into”). Therefore, the term used to describe what an MSC goes through when it matures is “multipotent differentiation.” Because MSC's have the ability to stem into needed cell types, they can greatly help healing when concentrated around an injured area. In addition to this, it is believed that MSC's simply improve the tissue microenvironment to make it more favorable towards healing because they release growth factors and cytokines (proteins that help with healing)[3].

As mentioned earlier, the two biggest storage locations for MSC’s in the body are fat (adipose) and bone marrow. Bone marrow had been used as an MSC source for many years, yet it was known that other tissues also contain MSC’s. So in the late 1990’s researchers began investigating other potential tissues for these cells and discovered that adipose had nearly identical regenerative abilities as did bone marrow.[4] In fact, adipose was also found to contain up to 2,000 times as many MSC’s as bone marrow.[5] There also exists strong evidence that, as a person ages, the regenerative power of MSC’s is better maintained in adipose than it is in bone marrow.[6] These facts make adipose a more ideal regenerative stem cell source, especially for older patients. Adipose is also easier to obtain, and its extraction is better tolerated by patients, with less risk, than is bone marrow extraction.

Mesenchymal Stem Cells: Adult Stem Cells
for Connective Tissue Healing

Mesenchymal stem cells (MSC’s) are essential to tissue regeneration and wound healing.[7] Multiple studies have confirmed that MSC’s help in healing of musculoskeletal tissue, specifically: ligament,[8] tendon,[9] cartilage,[10] disc,[11] and muscle.[12] An interesting observation about MSC’s is that the amount and potency of these cells in patients with degenerative joints are often severely low.[13] Therefore, it is logical that using MSC’s in the treatment of degenerative conditions would be beneficial.[14] Indeed, in degenerative diseases such as osteoarthritis (OA), regenerative therapies using MSC’s have been shown to be quite effective.[15]

Adipose as an Adult Mesenchymal Stem Cell Source

Adipose as a stem cell source has been well recognized for many years, with studies and papers appearing regularly in the medical literature. There is even an organization dedicated to the use of adipose for regenerative purposes, the International Federation for Adipose Therapeutics and Science (“IFATS”) which has been holding annual international scientific conferences since 2001. Scientists, engineers, and physicians from all over the world meet at these conferences every year to present and discuss the latest research, clinical uses, and controversies.[16]

Adipose as a stem cell source for repair within one’s body is logical because it is the one of the most abundant cell types, found near or in almost every organ. Adipose itself is a very complex tissue (see Figure 2: The structure of adipose). There are several different cell types within it, and there is regular discussion about which cell type does what. Some researchers claim it is not actually the MSC’s but another cell type in the adipose that are the true stem cells. These other cells surround blood vessels, and for that reason are called “pericytes” (peri meaning “around” and cyte meaning “hollow vessel”).[17] Since it is not known exactly which cells are the most regenerative, and since in adipose these cells exist in such high numbers, isolation of specific cells is usually not necessary or even desirable[18] In Biocellular Prolotherapy, we do not typically extract or isolate the MSC, but rather use the entire “smorgasbord” of cells (called “stroma”), letting the body take what it needs. This is why the term “stem/stromal” cell is sometimes used.

A microscopic view of some of the structures where mesenchymal stem cells can be found in adipose tissue.
Figure 2: The structure of adipose tissue - A. Fluid and tissue outside of the cells, called “Extracellular Matrix”, B. Adipose cells, C. Pericytes (surround blood vessels; important in new blood vessel formation) D. Mesenchymal Stem Cells - MSC’s (the little green guys)

Adipose and Platelet-Rich Plasma: Better Together

Studies have shown that using platelet-rich plasma and adipose tissue together “significantly improves” regeneration versus using adipose cells alone.[19] When adipose is used as the stem cell source, platelet-rich plasma is thus typically used at the same time since this has been shown to enhance results in multiple studies.[20] In one study, using adipose-derived cells with platelet-rich plasma, versus platelet-rich plasma alone on Achilles tendon injuries showed tendon strength for the adipose/platelet-rich plasma group to be greater, with a statistically higher production of collagen and growth factors.[21] Therefore, typically, adipose and platelet-rich plasma are done together during a Biocellular procedure.

The Phenomena of “Cellular Depletion” and the Extra Benefit of Biocellular Prolotherapy

When an area of the body has been repeatedly injured over a long period, a phenomenon called “cellular depletion” occurs. This means that in that depleted area, many of the adult stem cells present at birth that would normally be used for repair have already been used up, thus reducing the capacity for healing there. If local repair cells have been depleted, less aggressive forms of Prolotherapy may only go so far. Platelet-rich plasma works by sending biochemical signals for stem cells to come in to help repair an injury site. This signal is local (think of Bluetooth, which is a short-range signal), which means there must be stem cells within a certain distance of the platelets’ signal in order for the signal to be effective. When there is cellular depletion, very few stem cells are close enough to “hear” the platelets’ cry for help. (see Figure 3: What happens when there is cellular depletion). Such is the beauty of Biocellular Prolotherapy, since the treatment itself provides healthy adult stem cell sources directly to the depleted injury site.

Activated Platelets signaling to Mesenchymal Stem Cells
Figure 3: What happens when there is cellular depletion. Activated platelets signal for help, however few or no adult stem (repair) cells are within range to respond.

Biocellular Prolotherapy for Osteoarthritis (OA)

Osteoarthritis can be inflammatory, destructive, and progressive. Adult stem cells have been shown to both control inflammation and improve blood flow in joints, thereby slowing OA's progression.[22] Studies in animal OA models consistently demonstrate that adult stem cells prevent both the destruction of cartilage and further OA bone spurring, as well as improve existing ligament and meniscal damage.[23] An advantage of adult stem cells is that they seem to have the ability to “home in on”—to perceive and travel to—injured tissue; once there, they secrete growth factors and other elements that both help stop destructive inflammation and contribute to tissue repair.[24] This is in contrast to conventional treatments such as medication, physical therapy, hyaluronic acid, and cortisone injections; although these traditional remedies can relieve pain, they neither stop the progression of joint degeneration nor offer any regenerative capacity.[25] Both types of stem cell sources, bone marrow and adipose, are used in the treatment of OA.

Biocellular Stem-Cell Rich Prolotherapy treatment of arthritic joints
Biocellular Stem-Cell Rich Prolotherapy treatment of arthritic joints.

The Choice of Biocellular Formula: Adipose versus Bone Marrow

The choice of which stem cell source to use in Biocellular Prolotherapy depends on several factors, including the condition being treated, the age of the patient, the physician’s background and training, and the patient’s preference.

While adipose and bone marrow formulas have demonstrated similar treatment capabilities, there does appear to be functional differences between them. Some animal and laboratory studies indicate that bone marrow may be preferred and more efficient for osteochondral (bone and cartilage) regeneration.[26] However, adipose has shown an excellent ability to stimulate cartilage regeneration,[27] and there are many studies that indicate similar chondrogenic (ability to make cartilage) potential between bone marrow–derived and adipose-derived MSC’s.[28]

In a recent case report, a patient received surgery for a cartilage defect, which is the traditional treatment. This particular patient had a condition called osteochondritis dissecans (a joint condition in which bone underneath the cartilage of a joint dies due to lack of blood flow; the bone can break lose and cause pain), which can be serious. However, that surgery failed. The patient then received an injection of autologous adipose-derived MSC’s into the area. The result was structural and functional improvement, as well as reduction of pain levels.[29]

In multiple studies, both adipose and bone marrow stem cells have shown the ability to change the microenvironment more favorably toward healing and to decrease “bad” inflammation while promoting “good” inflammation and blood supply, helping to reduce pain and stimulate repair. However adipose is considered by some researchers to be better in this ability.[30] There are also several advantages that adipose has over bone marrow for ligament, tendon, and muscle repair,[31] especially in certain joints. For these reasons, adipose is becoming the preferred choice for connective tissue injury treatment.

The Advantage of Adipose-Derived Biocellular Prolotherapy
for Knee Osteoarthritis: The Fat Pad

Adipose-derived Biocellular Prolotherapy can also be an excellent treatment for knee OA because of its ability to replenish a structure in the knee called the “infrapatellar fat pad”[32] (infra meaning “under” and patella for the kneecap, so named because this fat pad sits directly under the kneecap). The fat pad is believed to be an important reservoir of regenerative cells,[33] including potent mesenchymal stem cells which have the ability to become cartilage.[34] A healthy fat pad has been found to help in the prevention or progression of OA.[35] In fact, a simple fat transfer (taking fat from another place in the body and injecting into the knee joint) has been shown to help knee osteoarthritis pain in a recent study. The authors believed that this not only improved cushioning provided by the fat pad, but supplied stem cells to replenish that important tissue.[36]

As a person ages or experiences trauma, and there is wear and tear, the fat pad may lose volume, along with the stem cells within it becoming depleted (used up) or injured.[37]

Age-related, fat-pad depletion has been associated with anterior knee pain and the development of OA,[38] and there is a strong correlation between the size and condition of a patient’s fat pad and the severity of his or her pain and OA progression.[39] Also interesting is that removal of the fat pad during surgery has been associated with increased pain,[40] so clearly this structure is important in the health of the knee. With the adipose-derived Biocellular procedure, good fat taken from elsewhere in the body is transferred to a depleted fat pad. It is logical that this has the potential to restore this regenerative reservoir of cells and to improve the healing environment. The many cases of adipose-derived Biocellular Prolotherapy that have been completed since 2011 show just that: not only pain reduction and improved function but also objective ultrasound evidence demonstrating infrapatellar fat-pad improvement after treatment (see Figure 4: Ultrasound appearance of fat pad before and after adipose-derived Biocellular (Stem Cell–Rich) Prolotherapy). For all these reasons, adipose (fat) as a stem cell source appears to be a more logical choice to treat knee OA.

Two ultrasound image comparisons of the Knee Infrapatellar Fat Pad Before and after Biocellular Prolotherapy (adipose derived)
Figure 4: Knee Infrapatellar Fat Pad Before and after Biocellular Prolotherapy (adipose derived)

Biocellular Safety Concerns/Risk

As with any medical procedure, Biocellular Prolotherapy involves some risk, although when done by a properly trained professional, the risk is low. There is the risk of bruising and mild discomfort at the extraction site; this typically lasts for a few days up to perhaps a few weeks, but rarely longer. There is also the risk of infection at the extraction site, but this is extremely rare. An additional risk when extracting adipose could be minimal skin surface irregularity or dimpling at the fat extraction site, but since the amount of fat needed is so small, this is also extremely rare, especially when done by an experienced physician. With bone marrow extraction, there is the risk that the extraction site may remain sore for a period of time, however this is not common.

The question of safety also arises whenever cells capable of growth are introduced into a person. However, taking a person’s own stem cell-rich tissues and then giving them back to that same person has been shown to be very safe. One study monitored 1,873 patients for 21 years who had been treated with bone marrow cells between 1990 to 2006. During that monitoring period, the researchers found “no increased cancer risk” either at the treatment site or elsewhere.[41] Another study followed 91 patients for over two years who had been treated for various orthopedic conditions with adipose-derived cells mixed with platelet-rich plasma and found no tumor formation at any site treated (a total of 100 joints).[42]

Both bone marrow and adipose stem cells have also been used to repair injured cardiac muscle. As of 2014, more than 700 heart disease patients worldwide have received adult stem cell–based therapies with no indication of tumor growth ever reported.[43] In 2016, the Journal of Orthopaedic Surgery and Research concluded that the “use of MSC’s in the clinical setting can be considered safe, since no major adverse events related to the treatment nor to the cell harvest have been reported”, and that regardless of cell source or method, studies showed a high success.[44]

A few other procedure-related risks involving the extraction and injection of cells during this type of procedure exist in theory. This includes the theoretical risk for a blood clot; however, at the time of this writing there have been zero such events reported with the use of the microcannula harvesting system (a gentle method used in extracting adipose). Nonetheless, all potential risks should be discussed prior to treatment with the physician performing the procedure.