The ability for bone to naturally repair fractures and other common injuries have been well documented. However, research has consistently demonstrated that as they age, bone loses its ability to heal, repair, and fend off various bone diseases. In fact, each year, in the U.S. alone, there are over 2 million fragility-associated fractures with associated healthcare costs exceeding more than $20 billion dollars.
Currently, non-stem cell bone healing therapies including estrogen and related agonists, recombinant parathyroid hormone, supplements such as vitamin D and calcium exist, but with limitations and a number of potentially serious side effects.
Considering that the incidence of fracture and the associate rate of morbidity increase with age, current research is now examining other therapeutic options for the structural and functional restoration of bone, including the viability and of tissue engineering applications such as mesenchymal stem cells (MSCs) and bioscaffolding as potential solutions for the structural and functional restoration of bone.
Stem cells are generally used therapeutically in three distinct ways, including 1.) freshly isolated stem cells transplanted directly into tissue and undergo in vivo differentiation to become a desired cell type; 2.) the stem cell can be manipulated in vitro prior to being implanted; or 3.) circulating endogenous stem cells are recruited by cytokines to facilitate cell proliferation, migration, adhesion, and differentiation.
As researchers continue to explore using MSCs as part of therapeutic bone regeneration, it is generally accepted that MSC bone marrow density and quality decrease with age. In addition, a factor in determining the effectiveness of MSCs related to facilitating tissue repair is the ability for the stem cells to be directed to the site of injury, a process more commonly known as “homing”. A recent study using mice has demonstrated that MSCs appear to lose their homing ability rapidly while young MSCs demonstrate better homing ability, especially when compared to old MSCs. Considering this, future research must consider the age of both donor and recipient when determining the effectiveness of this strategy.
In addition to stem cells, bioscaffolds are also considered an essential component of the bone regeneration strategy, serving as the reservoir for multiple factors, the carrier for cells, the filler for the void space, and the template for bone regeneration. The ideal scaffold for bone tissue engineering has been identified as:
- Showing no local and systemic toxic effects to the host tissue
- Supporting normal cellular activity
- Allowing cell adhesion, proliferation, extracellular matrix deposition, and inducting new bone formation
- Prompting the formation of blood vessels after weeks of implantation.
Considering the above, several substrates have been identified as potential bioscaffolds to support improved regeneration of bone tissue, including decellularized extracellular matrix scaffolds, synthetic scaffolds (calcium phosphate-based bioactive ceramic scaffolds; metallic scaffolds (including metal scaffolds coated with growth factors and other bioactive factors); hybrid scaffolds combining two or more materials (metal-ceramic-poly hybrid scaffolds); natural and synthetic polymeric scaffolds; and nanomaterial-based scaffolds.
As research continues to explore the possibilities of new therapeutic approaches to bone healing provided through various tissue engineering applications, the use of MSCs and bioscaffolds continue to demonstrate potential benefits. Among the key areas requiring further study is the need to develop vascularization in engineered bone material. Bone and bone tissue has a rich vascular supply; while the recent study has demonstrated nanomaterials as having the potential to promote vascularization (without the aid of growth factors), further research and clinical trial are required.
Reference: (2018, June 22). Bone Marrow Mesenchymal Stem Cells: Aging … – NCBI – NIH. Retrieved December 18, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6733253/
Promising early research shows that when introduced into a brain injured by stroke, extracellular vesicles (EVs), also known as exosomes, a bioactive substance secreted by mesenchymal stem cells, have been associated with improved blood vessels creation, increased formation of neurons, and enhanced preservation of the neurological structure; these findings demonstrate a promising stem cell-derived stroke therapy that serves as an alternative approach to current stem cell infusion treatment options.
With nearly 14 million people suffering strokes each year, strokes continue to be the leading cause of physical disability among adults; between 25 percent and 50 percent of stroke survivors are left with significant and debilitating disabilities.
Because mesenchymal stem cells, or MSCs, secrete extracellular vesicles thought to reduce inflammation, enhance autophagy, and promote regeneration of damaged cells, researchers evaluating potential regenerative strategies for stroke-induced neurologic deficits have identified these MSC-derived EVs as a viable option for stroke therapy.
Although the reported beneficial effects of EV therapy has been observed in studies completed on animals, there is an increasing number of clinical studies currently being conducted on humans that suggest MSC EV stem cell therapy is a potentially safe and effective therapeutic option to improve outcomes in several various human applications.
Specifically, this EV-mediated therapy appears to offer an off-the-shelf treatment option that is potentially effective in crossing the blood-brain-barrier (BBB) while also avoiding cell-related problems, including the formation of tumors and infarcts resulting from vascular occlusions, or blood clots, consistent with those observed in acute ischemic stroke.
While there appears to be a promising upside to MSC EV therapy for the treatment of stroke, studies are on-going to discover the optimal therapeutic treatment of stroke patients. Some areas to continue researching are the optimal time and best mode of application of EVs in stroke patients (most stroke-related recovery occurs in the first few months following the stroke).
As research continues into the effectiveness of MSC-EV therapy for stroke, early indications are that EVs derived from mesenchymal stem cells could be a viable cell-free treatment option for patients recovering from a severe stroke.
Source: (2019, March 12). Mesenchymal Stem Cell-Derived Extracellular Vesicle …. Retrieved December 4, 2020, from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6422999/
Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive disease of the lungs that causes fibrosis of the spaces between the air sacs. As the fibrosis gets progressively worse, the movement of the lungs is more and more restricted. In effect, patients with IPF find it harder and harder to breathe. Patients become short of breath almost constantly.
The “idiopathic” part of idiopathic pulmonary fibrosis means that the cause is unknown. We know that it mainly occurs in older people, usually to people between the ages of 55 and 75—but we don’t know why.
Eventually, most people with IPF will need supplemental oxygen for all activities. Supplemental oxygen may delay some of the consequences of IPF (e.g. pulmonary hypertension), but it is mostly used to help patients breathe more easily and get more oxygen into the blood.
Two antifibrotic drugs, nintedanib, and pirfenidone are approved for the treatment of patients with idiopathic pulmonary fibrosis. In some patients with mild to moderate disease, these drugs can delay the progression of IPF for weeks to months. Both drugs are associated with significant side effects and patients may stop taking them because of these adverse events. Even if patients can tolerate the drugs, they do not repair or rebuild lung tissue, so they only help to slow the progression.
Scientists have suggested an alternate approach; one in which an antifibrotic drug is given alongside a treatment intended to regenerate the lung tissue, namely, mesenchymal stem cells. They persuasively argue that mesenchymal stem cells can regulate the immune system by reducing the inflammation that occurs in idiopathic pulmonary fibrosis. Stem cells also differentiate into functional alveolar cells, i.e., the cells that are part of air sacs. Perhaps more impressively, bone marrow-derived stem cells had the same short-term therapeutic benefits as pirfenidone in mice with experimental IPF.
The authors do not advocate that stem cells should be used to replace the antifibrotic drugs, nintedanib, and pirfenidone, but they do suggest that stem cell treatment could be useful in combination with one of these drugs. They theorize that the antifibrotic drug can reduce symptoms, but the stem cell treatment may help also reduce symptoms but also slow down, stop, or even reverse the progression of the disease. More clinical work is needed, but since IPF is a terrible disease with no cure, that work will hopefully be done quite soon.
Reference: Chuang, Hong-Meng, et al. (2018). Mesenchymal Stem Cell Therapy of Pulmonary Fibrosis Improvement with Target Combination. Cell Transplantation. 2018; Vol. 27(11) 1581-1587.
Osteoarthritis is the most common form of arthritis. In osteoarthritis, the cartilage of the joints breaks down, bone spurs form, the synovial linings become inflamed, and the ligaments around the joint calcify. All of these pathological changes combine to cause joint pain, swelling, and stiffness. The breakdown of the joint also means that it does not function properly. The arthritic joint may “lock up,” “give out,” or simply not be able to move through its normal range of motion. Early in the disease, the pain of osteoarthritis may be brought on by movement. Later, the pain is more or less constant with severe pain flares.
Initially, the treatment for osteoarthritis is pain medications, exercise, braces, and physical therapy. Joint injections may be helpful for 4 to 6 weeks, but recent research suggests that repeated steroid injections may break down cartilage and speed up joint destruction. Unlike treatments for rheumatoid arthritis, there are no disease-modifying treatments for osteoarthritis. The disease tends to get worse over time until surgery is required. Joint replacement surgery is usually the treatment of last resort.
Since osteoarthritis is a degenerative joint disease, a reasonable approach to therapy is to try to rebuild or regenerate the joint tissues. This would not only stop the disease progression of osteoarthritis but perhaps even heal the damaged joint. For this reason, regenerative medicine, also known as stem cell therapy, is drawing the attention of many scientists who are looking for alternative therapeutic treatments for osteoarthritis.
Researchers tested the ability of mesenchymal stem cells to relieve pain and treat the damage of osteoarthritis. More specifically, they used the exosomes that the mesenchymal stem cells produce. Exosomes are tiny packets of substances like RNA and peptides that support tissue growth and repair. Exosomes contain most of the molecules that make mesenchymal stem cells helpful.
The scientists found that giving exosomes from mesenchymal stem cells to animal subjects with experimental osteoarthritis had some remarkable effects. Not only did the stem cell-derived treatment substantially reduce pain in the rats with osteoarthritis, but microscopic and molecular evidence also showed that the exosomes were able to repair cartilage in the affected joints. This is truly impressive when you consider that other treatments for osteoarthritis only reduce symptoms—they do not repair cartilage or stop the progression of the disease.
While this work will need to be replicated in human clinical studies (and that work has already begun), this is an exciting finding for the millions of Americans who struggle with osteoarthritis.
Reference: He, L., He, T., Xing, J. et al. Bone marrow mesenchymal stem cell-derived exosomes protect cartilage damage and relieve knee osteoarthritis pain in a rat model of osteoarthritis. Stem Cell Res Ther 11, 276 (2020). https://doi.org/10.1186/s13287-020-01781-w
Rheumatoid arthritis causes chronic inflammation of multiple joints throughout the body. This joint inflammation eventually causes the cartilage and bone to break down, and the tendons and ligaments surrounding the joints stretch and become deformed. Consequently, people with rheumatoid arthritis experience pain and loss of function in affected joints.
Unfortunately, rheumatoid arthritis is not just a disease of joints. Rheumatoid arthritis also causes systemic inflammation. People with rheumatoid arthritis commonly experienced fevers, weight loss, and chronic fatigue. Many patients report being achy or stiff apart from joints directly affected by arthritis. Rheumatoid arthritis can cause bone loss, muscle weakness, skin lesions, and kidney disease. Patients may also experience lung, heart, and vascular diseases.
The cause of rheumatoid arthritis is unknown; however, since it is an inflammatory disease, the main treatment for rheumatoid arthritis is an anti-inflammatory medication. Some lifestyle changes may help to ease some of the symptoms but most physicians initially recommend using a disease-modifying antirheumatic drug or DMARD soon after rheumatoid arthritis is diagnosed. DMARDs can modestly reduce symptoms of rheumatoid arthritis and help reduce the risk of patients developing debilitating joint abnormalities. DMARDs include drugs such as methotrexate or biologics such as infliximab or tofacitinib. Patients with rheumatoid arthritis usually also must take glucocorticoids, i.e. steroids to acutely control inflammation. Unfortunately, these agents have considerable side effects, especially when taken for long periods of time. Moreover, the treatments are not curative. As such, researchers are still looking for better treatments for rheumatoid arthritis.
Scientists recently conducted a prospective Phase 1/2 study of umbilical cord mesenchymal stem cells in patients with rheumatoid arthritis. They selected 64 patients with rheumatoid arthritis between the ages of 18 and 64. Volunteers received an intravenous infusion of mesenchymal stem cells and were followed for three years. At both the 1 and 3 years follow up appointments, the rheumatoid arthritis patients treated with mesenchymal stem cells had substantially lower levels of the blood markers that indicate rheumatoid arthritis (namely C-reactive protein, elevated erythrocyte sedimentation rate, rheumatoid factor, and anti-CCP antibody). The test of physical function also significantly improved at 1 and 3 years after stem cell treatment [Health Index (HAQ) and Joint Function Index (DAS28)]. The treatment was also safe, and no serious adverse effects were reported.
The results of this stem cell clinical trial are particularly remarkable because patients received only one intravenous treatment and enjoyed at least three years of improvement in their disease both in the blood markers but also in symptoms and physical functioning. Although not a cure, this study shows the apparent safety of mesenchymal stem cell treatment and the impressive benefits to allow patients to consider researching stem cell therapy as an alternative option for their rheumatoid arthritis symptom management. Indeed, if additional larger studies confirm these impressive results, umbilical cord mesenchymal stem cell treatment may become a possible standard of care in the treatment of rheumatoid arthritis in the future.
Reference: Wang L, Huang S, Li S, et al. Efficacy and Safety of Umbilical Cord Mesenchymal Stem Cell Therapy for Rheumatoid Arthritis Patients: A Prospective Phase I/II Study. Drug Des Devel Ther. 2019;13:4331-4340. Published 2019 Dec 19. doi:10.2147/DDDT.S225613
Scientists have long realized that Multiple Sclerosis (MS) is an inflammatory disease and that the immune system, in a manner, attacks the brain and spinal cord. These inflammatory lesions cause patients to have severe neurological symptoms. Therefore, treatments for multiple sclerosis have focused on controlling the immune system.
The current treatments for Multiple Sclerosis can help minimize the severity of the disease, but they may cause serious side effects. Consequently, researchers are constantly looker for newer, safer, less expensive alternatives.
While the precise cause of MS is still unknown, multiple sclerosis lesions contain high levels of an immune cell, specifically CD4+ T cells. These T cells become active in the central nervous system and interfere with the function of other T cells (regulatory T cells). Simply put, whatever causes MS creates abnormal regulatory T cells; healthy regulatory T cells are important for maintaining a balance between helpful and harmful immune system functions.
In the scientific research journal Oncotarget, Yang and co-authors showed experimentally for the first time that umbilical cord-derived mesenchymal stem cells could repair defective regulatory T cells in patients with Multiple Sclerosis.
The scientists collected mesenchymal stem cells from umbilical cord tissue (the tissue that is usually thrown away as medical waste after live birth). They also collected peripheral blood mononuclear cells (i.e. T cells, B cells, natural killer cells, and monocytes) from patients with MS and healthy volunteers. Stem cells and peripheral blood mononuclear cells were combined in the lab for 3 days. After incubation, samples with stem cells had a higher proportion of regulatory T cells, and those regulatory T cells had greatly improved their function. In fact, stem cell treatment made the defective regulatory T cells function much like regulatory T cells from healthy volunteers.
Continued studies are needed, but the proof of concept has shown positive results and to be safe in many clinical trials. Thus, if umbilical cord-derived mesenchymal stem cells have the potential to improve regulatory T cell function in patients with MS, there is hope for an alternative option for those seeking to manage symptoms caused by multiple sclerosis.
Reference: Yang, H., et al. (2016). Umbilical cord-derived mesenchymal stem cells reversed the suppressive deficiency of T regulatory cells from peripheral blood of patients with multiple sclerosis in a co-culture – a preliminary study. Oncotarget. 2016; 7:72537-72545.