MESENCHYMAL STEM CELLS
Over the last decade, cellular therapy has developed quickly at the level of in vitro and in vivo preclinical research and in clinical trials. Thus, one of the types of adult stem cells that have provided a great amount of interest in the field of regenerative medicine due to their unique biological properties is Mesenchymal stem cells (MSCs).
Mesenchymal stem cells (MSCs) are known to be multipotent stromal cells that can differentiate into a variety of cell types which include osteoblasts (bone cells), chondrocytes (cartilage cells), myocytes (muscle cells) and adipocytes (fat cells which give rise to marrow adipose tissue). Furthermore, MSCs are responsible for tissue repair, growth, wound healing and cell substitution resulting from physiological or pathological causes; they have various therapeutic applications such as in the treatment of central nervous system afflictions like spinal cord lesions (1). Similarly, they are characterized by an extensive capacity for self-renewal, proliferation, potential to differentiate into multiple lineages and their immune-modulatory role on various cells.
Mesenchymal stem cells have the ability to expand in many folds in culture while retaining their growth and multilineage potential. Also, they can be identified by the expression of many molecules including CD105 (SH2) CD73 and CD34, CD45. Thus, these properties of MSCs make these cells potentially ideal candidates for tissue technology.
In addition, it has been discovered that MSCs, when transplanted systemically, have the ability to transport to sites of physical harm or damage in animals, suggesting that MSCs have migratory capacity. This migration property of MSCs is important in regenerative medicine, where various injection routes are utilized depending on the damaged tissue or organ.
The first source of Mesenchymal stem cells was in the bone marrow and considered to be the gold standard for clinical research, although various other sources have being discovered which include: Adipose tissue, Dental pulp, Mobilised Peripheral blood, Amniotic fluid, Joint synovium, synovial fluid, Endosteum, Periosteum, Menstrual blood and birth-derived tissues.
Cohnheim (German Biologist) hypothesized in the late nineteenth century that fibroblastic cells derived from bone marrow were involved in wound healing throughout the body, while in 1970, Alexander Friedenstein described a population of plastic-adherent cells that emerged from long-term cultures of bone marrow and other blood-forming organs, and he showed to have colony forming capacity and osteogenic differentiation characteristics in vitro as well as in vivo upon re-transplantation.
Arnold Caplan (1991), coined the term “mesenchymal stem cell and stated that the cells as multipotent mesenchymal cell populations which can differentiate into several tissue types, and demonstrated roles for MSCs in the regeneration of bone, cartilage or ligaments in animal and clinical studies. However, the first clinical trials of MSCs were completed in 1995 when a group of 15 patients were injected with cultured MSCs to test the safety of the treatment.
According to International Society for Cellular Therapy, the proposed minimum criteria to define MSCs include the following:
(a) The cells should exhibits plastic adherence
(b) The cell should possess specific set of cell surface markers, i.e. cluster of differentiation (CD) 73, D90, CD105 and lack expression of CD14, CD34, CD45 and human leucocyte antigen-DR (HLA-DR).
(c) The cells should have the ability to differentiate in vitro into adipocyte, chondrocyte and osteoblast.
Thus, these characteristics are valid for all MSCs, although few differences exist in MSCs isolated from various tissue origins.
Mesenchymal stem/stromal cells (MSCs) can be isolated from neonatal tissues, most of which are discarded after birth, including placental tissues, fetal membranes, umbilical cord, and amniotic fluid. Placenta is an ideal starting material for the large-scale manufacture of multiple cell doses of allogeneic MSC. The placenta is a fetomaternal organ from which either fetal or maternal tissue can be isolated.
MSC derived from placenta have long-term proliferation and immunomodulatory capacity, superior to bone marrow-derived MSC. The placenta is a fetomaternal organ consisting of both fetal and maternal tissue, and thus MSC of fetal or maternal origin can be, theoretically isolated. Thus, neonatal tissues are easily available and they have biological advantages in comparison to adult sources that make them a useful source for stem cells including MSCs. They appear to be more primitive and have greater multipotentiality than their adult counterparts.
Ø MSCs have been widely used to treat immune-based disorders, such as Crohn’s disease, rheumatoid arthritis, diabetes, and multiple sclerosis.
Ø MSCs have been widely used as a treatment for numerous orthopedic diseases, including bone defects, osteoarthritis (OA), femoral head necrosis, degenerative disc, spinal cord injury, knee varus, osteogenesis imperfecta, and other systemic bone diseases.
Ø MSCs are promising cell source for treatment of autoimmune, degenerative and inflammatory diseases due to the homing ability, multilineage potential, secretion of anti-inflammatory molecules and immunoregulatory effects.
Ø MSCs play a key role in the maintenance of bone marrow homeostasis and regulate the maturation of both hematopoietic and non-hematopoietic cells.
Ø MSCs have been shown to be powerful tools in gene therapies, and can be effectively transduced with viral vectors containing a therapeutic gene, as well as with cDNA for specific proteins, expression of which is desired in a patient.
Ø It has been proved that MSCs can differentiate into insulin producing cells and have the capacity to regulate the immunomodulatory effects
- Wei X, Yang X, Han ZP, Qu FF, Shao L, Shi YF. Mesenchymal stem cells: a new trend for cell therapy. Acta Pharmacol Sin. 2013 Jun; 34(6):747-54
- Friedenstein AJ, Piatetzky II S, Petrakova KV. Osteogenesis in transplants of bone marrow cells. J Embryol Exp Morphol. 1966;16:381–90
- Friedenstein AJ, Chailakhyan RK, Latsinik NV, Panasyuk AF, Keiliss-Borok IV. Stromal cells responsible for transferring the microenvironment of the hemopoietic tissues. Cloning in vitro and retransplantation in vivo. Transplantation. 1974;17:331–40.
- Pittenger MF, Mackay AM, Beck SC, Jaiswal RK, Douglas R, Mosca JD, et al. Multilineage potential of adult human mesenchymal stem cells. Science. 1999;284:143–7.
- Caplan AI, Dennis JE. Mesenchymal stem cells as trophic mediators. J Cell Biochem. 2006;98:1076–84.
- Wang S, Qu X, Zhao RC. Clinical applications of mesenchymal stem cells. Journal ofHematology & Oncology. Apr 30, 2012;5:19.
- Dominici, M., Le Blanc, K., Mueller, I., Slaper-Cortenbach, I., Marini, F., Krause, D., Deans, R., Keating, A., Prockop, D. and Horwitz, E. (2006) Minimal criteria for defining multipotent mesenchymal stromal cells. The International Society for Cellular. Therapy position statement. Cytotherapy 8, 315–317
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Which are the best options For Treating Common Sports Injuries?
As physicians, we are constantly dealing with sports injuries. While they are typically not seen as life-threatening with high chances of recovery, they could potentially cause further problems down the line for the patient. Sports injuries can also take months to heal and getting patients back on their feet can take a lot of time, effort and money, which can be frustrating for patients who want to get back to playing football every weekend or for those who have a skiing holiday booked in the next month.
Recently, there has been a massive surge in the use of stem cells as an alternative treatment to common sports injuries. This article aims to outline the benefits and risks attached to using stem cells and how this alternative treatment may help patients who are suffering from common sports injuries.
What Are The Most Common Sports Injuries?
We are constantly treating sports injuries on a regular basis. Some of the most common sports injuries doctors typically deal with are:
An ankle sprain occurs when the ligaments in the ankle are stretched and eventually torn due to twisting or falling onto the foot. Ankle sprains are common among athletes and sports enthusiasts, however, if left untreated, the ankle can weaken, making it more vulnerable to further damage. This leads to long term problems such as chronic ankle pain, arthritis, and ongoing instability.
A sprained ankle can be easily diagnosed when we see displays of swelling, bruising, stiffness and pain when we attempt to touch or move the ankle.
A groin pull is basically a groin strain. Strains occur when the muscles are overstretched, moving in directions that are not normal for them or pulled too forcefully or suddenly. This leaves them torn and damaged and results in tenderness and bruising in the groin and inner thigh area. This injury is common in athletes that play sports which require a lot of quick side-to-side movements.
A groin pull can be easily diagnosed after a thorough physical examination of the symptoms and possible tests such as x-rays and MRI’s.
A hamstring strain occurs when the three muscles in the back of the thigh are overstretched from movements such as hurdling and kicking the leg out sharply. As these muscles are naturally tight and susceptible to sprains, it can take from six to twelve months to heal and are vulnerable to recurring injuries. Poor or lack of stretching are the likely causes of a pulled hamstring.
Shin Splints is an inflammation of the muscles in the lower leg when they are overworked and stressed. Shin splints are often found in athletes that engage in sports that require a lot of running, dodging or quick stops and starts.
Knee injury: ACL tear
An ACL knee injury is a tear or sprain of the ligament that holds the leg bone to the knee. Sudden stops or changes in direction can tear the ACL and make that dreaded “pop” sound. Almost immediately, the knee will swell, feel unstable and be too painful to bear weight. This injury is common in athletes that engage in sports such as soccer, basketball, and downhill skiing.
ACL tears are commonly seen as a severe sports injury and can be traditionally treated with rehabilitation programs and surgery to strengthen or completely replace the torn ligament.
Knee injury: Patellofemoral Syndrome
Patellofemoral Syndrome occurs when repetitive movements of the kneecap (patella) are made against the thigh bone (femur) which damages the tissue. This knee pain is common among young adults and can be caused by a number of factors such as weakness in the thigh or buttock muscles, tight hamstrings, short ligaments around the kneecap or alignment problems through the feet.
Tennis Elbow (epicondylitis)
Tennis Elbow is common for athletes that play sports such as tennis or golf that require the player to ‘grip’ tightly and repetitively for an extended amount of time. This results in the ligaments of the forearm becoming strained and inflamed, making it painful to make wrist or hand motions.
What Are The Traditional Treatment Options & Management Strategies For Sports Injuries?
Traditional treatment methods and strategies for treating mild sports injuries such as sprains and strains can be done at home. Traditional advice given by doctors can include taking rest, applying ice to reduce the swelling and dressing the injury with compression bandages to support and assist healing. Nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen may also be prescribed to help reduce swelling and to relieve pain.
Moderate severity injuries may be traditionally treated with immobilization strategies such as the use of crutches or a cast brace to assist the ankle to heal for the first few weeks. This may be followed with rehabilitation exercises to strengthen the ankle and prevent stiffness and future problems.
Severe sports injuries such as knee injuries are traditionally treated with surgery or rehabilitation programs to replace or restore the torn ligaments or muscles. This also goes for those patients who experience persistent problems after months of nonsurgical treatment.
Whatever the severity level of the sports injury, the healing process can take up to several months before the muscle restores to its natural condition. Injuries can also leave muscles and ligaments permanently weakened and susceptible to further injury.
Is Stem Cell Therapy An Option For Treating Sports Injuries?
The use of stem cells to treat sports injuries are becoming more popular due to its ability to grow new blood vessels that facilitate faster and better healing, decrease or prevent inflammation and release proteins (cytokines) that can slow down tissue degeneration and reduce pain. Sports injuries that include damage to tendons, ligaments, muscles, and cartilage are reported to be seeing the best results from stem cell therapy.
Dr. Bill Johnson, MD of Innovations Medical sees stem cell therapy as a revolutionary alternative to painful surgery and long recovery and states that,
“Patients who undergo stem cell therapy for their sports injury report a reduction in their painful symptoms and increase range of motion and increased mobility. Stem cell therapy helps to quickly reduce joint inflammation, and many patients see improvements in 1 to 2 days. Anti-inflammatory results of the procedure can last for 2 to 3 months and many patients see a gradual improvement in their condition over time.”
Even celebrity athletes such as Peyton Manning and Ryan Tannehill have used stem cell treatment in conjunction with traditional treatments with success. Stem cells are placed directly into the joint via surgical application or injection to aid quicker healing and promote the growth of cells needed to restore strength and flexibility in muscles and ligaments.
However, using stem cells as an alternative method to treat sports injuries is still a controversial subject and is very much still debated among medical professionals. Research is still undergoing to show whether or not stem cell therapy is the best solution. Critics of this therapy argue the fact that stem cell therapy doesn’t work any better than a placebo and that there is no clear evidence that this type of therapy is safe. Unwanted side effects can include swelling and pain and if stem cells are used from other sources or manipulated in any way, this can result in a higher risk of developing tumors.
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How Stem Cell Therapies Can Help Heal Sports Injuries
Continuing our recent discussion of stem cell therapies for sports injuries, the use of mesanchysmal stem cells (MSCs) in orthopedic medicine can help in the repair of damaged tissue by harnessing the healing power of undifferentiated cells that form all other cells in our bodies. The process involves isolating these stem cells from a sample of your blood, bone marrow or adipose tissue (fat cells), and injecting it into the damaged body part to promote healing. Platelet-rich-plasma (PRP), a concentrated suspension of platelets (blood cells that cause clotting of blood) and growth factors, is also used to assist the process of repair.
Below are some examples of injuries and areas of research involving the use of mesenchymal stem cells (MSCs), which are (adult) tissue stem cells that are not only able to produce copies of themselves, but also able to divide and form bone, cartilage, muscle, and adipose (fat) stem cells when cultured under certain conditions:
Cartilage has long been considered as an ideal candidate for cell therapy as it is a relatively simple tissue, composed of one cell type, chondrocytes, and does not have a substantial blood-supply network. Of particular interest to researchers is repair of cartilage tissue in the knee, also called the meniscus of the knee. The meniscus is responsible for distributing the body’s weight at the knee joint when there is movement between the upper and lower leg. Only one third of meniscus cartilage has a blood supply, and as the blood supply allows healing factors and stem cells attached to the blood vessels (called perivascular stem cells) to access the damaged site, the meniscus’s natural lack of blood supply impairs healing of this tissue. Damage to this tissue is common in athletes, and is the target for surgery in 60 percent of patients undergoing knee operations, which usually involves the partial or complete removal of the meniscus, which can lead to long-term cartilage degeneration and osteoarthritis.
Recently, researchers increased their focus on the use of MSCs for treatment of cartilage damage in the knee. Some data from animal models suggest that damaged cartilage undergoes healing more efficiently when MSCs are injected into the injury, and this can be further enhanced if the MSCs are modified to produce growth factors associated with cartilage. It has been shown that once the MSCs are injected into the knee they attach themselves to the site of damage and begin to change into chondrocytes, promoting healing and repair. A small number of completed clinical trials in humans using MSCs to treat cartilage damage have reported some encouraging results, but these studies used very few patients, making it difficult to accurately interpret the results. There are currently a number of ongoing trials using larger groups of patients, and the hope is that these will provide more definite information about the role MSCs play in cartilage repair.
Tendinopathy relates to injuries that affect tendons – the long fibrous tissues that connect and transmit force from muscles to bones. Tendons become strained and damaged through repetitive use, making tendinopathy a common injury among athletes. Tendinopathy has been linked to 30 percent of all running-related injuries, and up to 40 percent of tennis players suffer from some form of elbow tendinopathy or “tennis elbow.” Damage occurs to the collagen fibers that make up the tendon, and this damage is repaired by the body through a process of inflammation and production of new fibers that fuse together with the undamaged tissue. However, this natural healing process can take up to a year to resolve, and results in the formation of a scar on the tendon tissue, reducing the tendon’s natural elasticity, decreasing the amount of energy the tissue can store and resulting in a weakening of tendon.
MSCs have the ability to generate cells called tenoblasts that mature into tenocytes. These tenocytes are responsible for producing collagen in tendons. This link between MSCs and collagen is the focus for researchers investigating how stem cells may help treat tendinopathy. Substantial research has been carried out on racehorses as they suffer from high rates of tendinopathy, and the injury is similar to that found in humans. Researchers discovered that by injecting MSCs isolated from an injured horse’s own bone marrow into the damaged tendon, recurrence rates were almost cut in half compared to horses that receive traditional medical management for this type of injury. A later study by the same group showed the MSCs improved repair, resulting in reduced stiffness of the tissue, decreased scarring and better fusion of the new fibers with the existing, undamaged tendon. It is not yet clear if these results are due to MSCs producing new tenocytes or their ability to modulate the environment around the tendinopathy, as described above. These promising results paved the way for the first pilot study in humans.
Bones are unique in that they have the ability to regenerate throughout life. Upon injury, such as a fracture, a series of events occur to initiate healing of the damaged bone. Initially there is inflammation at the site of injury, and a large number of signals are sent out. These signals attract MSCs, which begin to divide and increase their numbers. The MSCs then change into either chondrocytes, the cells responsible for making a type of cartilage scaffold, or osteoblasts, the cells that deposit the proteins and minerals that comprise the hard bone on to the cartilage. Finally these new structures are altered to restore shape and function to the repaired bone. A number of studies carried out in animals have demonstrated that direct injection or infusing the blood with MSCs can help heal fractures that previously failed to heal naturally. However, as was the case with tendinopathy, it is not yet clear if these external MSCs work by generating more bone-producing cells or through their ability to reduce inflammation and encourage restoration of the blood supply to injured bone, or both.
Brain injury in sports
There is mounting evidence that those taking part in sports where they are exposed to repetitive trauma to the head and brain are at a higher risk of developing neurodegenerative disorders, some of which are targets for stem cell treatments. For example, it has been reported that the rate of these diseases, like Alzheimer Disease, were almost four times higher in professional American football players compared to the general population. While the cause of this disease is not yet clear, it is associated with abnormal accumulation of proteins in neural cells that eventually undergo cell death and patients develop dementia. Researchers have attempted a number of strategies to investigate treatments of this disease in mice, including introducing neural stem cells that could produce healthy neurons. While some of these experiments have demonstrated positive, if limited, effects, to date there are no stem cell treatments available for Alzheimer’s Disease.
Boxers suffering from dementia pugilistica, a disease thought to result from damage to nerve cells, can also demonstrate some symptoms of Parkinson’s Disease (among others). In healthy brains, specialized nerve cells called dopaminergic neurons produce dopamine, a chemical that transmits signals to the part of the brain responsible for movement. The characteristic tremor and rigidity associated with Parkinson’s Disease is due to the loss of these dopaminergic neurons and the resulting loss of dopamine production. Researchers are able to use stem cells to generate dopaminergic neurons in the lab that are used to study the development and pathology of this disease. While a recent study reported that dopaminergic neurons derived from human embryonic stem cells improved some symptoms of the disease in mice and rats, stem cell based treatments are still in the development phase.
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