Systemic lupus erythematosus or simply “lupus” is a chronic inflammatory disease that can affect almost every organ and tissue in the body. Most people are aware of chronic fatigue, muscle and joint pain, and a characteristic facial skin rash that occurs in people with lupus. However, the disease can affect the gastrointestinal tract, lungs, heart, eyes, lymph nodes, and brain. About half of all people with lupus will develop problems in their kidneys related to the disease. The most common kidney problem caused by lupus is a condition known as lupus nephritis.
Lupus nephritis may not cause any outward symptoms, though some patients report foamy urine. Physicians usually detect lupus nephritis during routine urinalysis. Lupus nephritis causes the kidneys to leak substantial amounts of protein in the urine. Over time, this protein loss can cause swelling in the hands, ankles, and feet, and may interfere with kidney function.
The main way in which lupus nephritis is treated is by using strong immunosuppressants such as glucocorticoids (“steroids”; prednisone), cyclophosphamide or mycophenolate mofetil. These immunosuppressing drugs can cause a number of serious and perhaps permanent side effects. Making matters worse, some people with lupus continue to have worsening lupus nephritis even after using these immunosuppressive drugs. In these cases, there is very little that can be done to treat the disease.
In order to help this group of individuals for whom regular treatments did not stop lupus nephritis from progressing, researchers conducted a clinical trial to test the effect of stem cells on this illness. Researchers collected allogeneic mesenchymal stem cells from bone marrow and umbilical cord tissue. They then infused the stem cells in 81 patients with lupus nephritis and followed them for 12 months. Amazingly, 60.5% of patients enjoyed remission of their kidney disease by the 12-month visit. Kidney function (glomerular filtration rate; GFR) significantly improved in patients treated with mesenchymal stem cells. Likewise, total lupus disease activity (not just lupus nephritis) improved significantly 12 months after treatment. These improvements were so profound that patients were able to reduce their doses of prednisone and other immune-suppressing drugs. Importantly, the stem cells did not cause any apparent adverse effects.
If this work can be confirmed in subsequent clinical trials, it is exciting news for patients with lupus, especially those with lupus nephritis. This work suggests that stem cells may be able to reduce the doses of immunosuppressants currently used to treat lupus nephritis, and it may even stop the progression of this terrible illness in some patients. We eagerly await additional clinical research in this area.
Reference: Gu F et al. (2014). Allogeneic mesenchymal stem cell transplantation for lupus nephritis patients refractory to conventional therapy. Clinical Rheumatology. 2014 Nov;33(11):1611-9.
Mesenchymal stem cells have two unique and powerful properties that make them the focus of intense scientific research. First, mesenchymal stem cells can escape recognition by the immune system. In other words, when mesenchymal stem cells are infused into the body, the immune system does not recognize them as foreign and does not react to them. If the immune system did respond to the stem cells, it would cause an aggressive and potentially deadly allergic or immunologic response. Second, mesenchymal stem cells have the power to inhibit the immune system. This means mesenchymal stem cells could be used to treat immunological and autoimmune diseases such as Rheumatoid Arthritis, Systemic Lupus Erythematosus, Multiple Sclerosis, and Crohn’s Disease, among others. In essence, mesenchymal stem cells can affect the immune system without triggering an inflammatory response making them an ideal treatment for these diseases.
For some time, mesenchymal stem cells extracted from bone marrow were thought to be the only type of mesenchymal stem cells capable of beneficially affecting the immune system. This fact is not necessarily bad, but it does mean that mesenchymal stem cell donors must undergo a bone marrow procedure, which can be painful and expensive. It would be far better if doctors could use mesenchymal stem cells taken from easier-to-get tissues such as fat (adipose), umbilical cord blood, or Wharton’s jelly (umbilical cord tissue). Most people have adequate amounts of fat just under the skin, and umbilical cord blood and tissue are thrown away as medical waste every day.
Fortunately for patients, Dr. Yoo and colleagues showed that mesenchymal stem cells taken from fat tissue, umbilical cord blood, and Wharton’s jelly exhibit the same immunomodulatory properties as mesenchymal stem cells taken from bone marrow. The researchers showed that these types of mesenchymal stem cells were able to suppress T-cell proliferation as effectively as those cells taken from bone marrow. T-cell proliferation, it should be pointed out, is a key step in autoimmune inflammation that occurs in diseases such as rheumatoid arthritis and others.
In short, mesenchymal stem cells taken from easier-to-get tissues were just as effective at suppressing inflammation (in vitro) as those taken from bone marrow. These results will need to be confirmed in clinical studies; however, this approach will be much more convenient and less expensive for patients and donors if they can use mesenchymal stem cells taken from fat or umbilical cord rather than bone marrow and yet reap the same benefits.
Reference: Yoo KH et al. (2009). Comparison of immunomodulatory properties of mesenchymal stem cells derived from adult human tissues. Cell Immunology. 2009;259(2):150-6.
Much of the initial excitement surrounding stem cells was that they have the potential to become other types of cells. Add cardiac stem cells to a heart damaged by a heart attack, for example, and perhaps those stem cells will become new heart cells and restore heart function. While this does occur—stem cells differentiated mature into adult cells—a fascinating and potentially more exciting use of stem cells is for what they secrete rather than what they become.
Over the past few years, researchers have become increasingly interested in the beneficial substances that stem cells secrete. Researchers refer to the collection of substances that stem cell secretes as its secretome. Stem cell researchers grow various kinds of stem cells in the laboratory and then measure the substances that the stem cells secrete to identify its secretome.
Dr. Hsieh and coauthors discovered that stem cells taken from human umbilical cord secrete an astounding number of helpful molecules. The scientists collected mesenchymal stem cells from Wharton’s jelly (which is a substance found in the human umbilical cord that is normally thrown away as medical waste). They then compared those mesenchymal stem cells with stem cells taken from bone marrow. The researchers found that the umbilical cord mesenchymal stem cells produced molecules that help protect nerve cells, helps nerve cells grow, and help blood vessels grow. The effects were much greater than from cells taken from bone marrow.
One interesting result from their scientific study was the effect of umbilical cord mesenchymal stem cells on injured nerve cells. The researchers deprived brain cells of sugar and oxygen to mimic what the cells would experience during a stroke. The substances secreted by stem cells protected the nerve cells during this harsh treatment. This effect was much stronger in the umbilical cord stem cells compared to the bone marrow stem cells.
Another interesting result from this research was that umbilical cord mesenchymal stem cells helped blood vessel cells organize and form new blood vessels (“tubes”). This could be very important for establishing blood flow to damaged tissue from burns, frostbite, heart attack, or stroke.
These results show that mesenchymal stem cells taken from umbilical cord tissue (Wharton’s jelly) have a unique secretome, which is more potent than similar cells taken from bone marrow. This research is particularly important for patients who have suffered an ischemic stroke or heart attack, as it may provide a clue for a way to treat these conditions in the future.
Reference: Hsieh et al. (2013). Mesenchymal Stem Cells from Human Umbilical Cord Express Preferentially Secreted Factors Related to Neuroprotection, Neurogenesis, and Angiogenesis. PLOS One.2013; 8(8): e72604.
An ischemic stroke is a devastating event. An ischemic stroke is caused when a blood clot blocks blood flow to a portion of the brain. If the blood cannot deliver oxygen and nutrients, brain cells in the affected area die. Whatever functions that area of the brain once performed are now lost—brain cells do not regenerate the same way as other cells do.
Not surprisingly, researchers are trying to find ways to restore dead brain cells so that patients can regain function. Stem cells are one of the most promising options in this pursuit. Stem cells can reduce brain damage caused by ischemia (lack of blood flow, nutrients, and oxygen). Moreover, stem cells can help animals with stroke regain neurological function.
Scientists have wondered, however, whether mesenchymal stem cells taken from the umbilical cord can achieve the same effects. Umbilical cord tissue is plentiful and the cells taken from the umbilical cord have many incredible properties.
Dr. Zhang and researchers in his group extracted mesenchymal stem cells from umbilical cord tissue collected from humans. This umbilical cord tissue is usually thrown away after a baby is born, but researchers have been collecting this material because it is rich in mesenchymal stem cells. The researchers then created ischemic strokes in rats by blocking one of the arteries to the brain. They then used stem cells to try to block the damaging effect of stroke in these rats.
The stem cells were given to the rats intravenously. The stem cells moved from the bloodstream into the brain and collected in the area of the stroke. Some of the stem cells actually became new brain cells in the damaged area. Moreover, rats treated with stem cells had better physical functioning than animals who did not receive stem cell treatment.
While this study was performed in rats, the implications for humans are profound. This work shows that mesenchymal stem cells taken from the umbilical cord are capable of improving function after stroke. This is exited news since it is much easier to obtain stem cells from umbilical cord tissue that it is from bone marrow (which requires an invasive procedure).
Reference: Zhang, Lei et al. (2017). Neural differentiation of human Wharton’s jelly-derived mesenchymal stem cells improves the recovery of neurological function after transplantation in ischemic stroke rats. Neural Regeneration Research. 2017 Jul; 12(7): 1103–1110.
Most organs of the body recover from injury by generating new, healthy cells. Not every organ of the body has the same ability to form new cells, however. The skin is an example of an organ that has an amazing ability to regenerate. Liver and lung also have the ability to form new cells, but not as dramatically as skin. Kidney and heart have even less ability to repair and regenerate. On the opposite end of the spectrum from the skin is the brain, which has very little capacity to regenerate once it has been damaged or destroyed. All of these organ systems, especially those that are relatively unable to repair themselves, could theoretically benefit from stem cells.
Mesenchymal stem cells, also known as stromal cells, are multipotent stem cells derived from bone marrow, umbilical cord, placenta, or adipose (fat) tissue. These cells can become the cells that make up bone, cartilage, fat, heart, blood vessels, and even brain. Mesenchymal stem cells have shown a remarkable ability to help the body to produce new cells. Researchers are now realizing that the substances stem cells release may be more important than any new cells they may become. In other words, stem cells can directly become new healthy cells to a certain degree, but they can also release substances that dramatically increase the number of new, healthy cells.
Mesenchymal stromal stem cells release small packets called exosomes. These exosomes are filled with various substances that promote cell and tissue growth. Some of the most interesting and potentially useful substances are cytokines and micro RNA. Cytokines are the traffic cops of cellular repair, signaling certain events to take place while stopping others. Having the right cytokines in a particular area is critical for new tissue growth. The micro RNA released by stem cell exosomes is potentially even more exciting than cytokines. These tiny bits of RNA can directly affect how healthy and diseased cells behave. Micro RNA has a powerful ability to control the biological machinery inside of cells.
Exosomes exhibit a wide array of biological effects that promote the repair and growth of damaged and diseased organs. They promote the growth of skin cells and help wounds heal. Exosomes can reduce lung swelling and inflammation and even help the lung tissue heal itself (i.e. reduced pulmonary hypertension, decrease ventricular hypertrophy, and improve lung vascular remodeling). These small packets released by stem cells help prevent liver cells from dying (i.e. prevents apoptosis), promote liver cell regeneration, and slow down liver cirrhosis (i.e. fibrosis). Exosomes can also help protect the kidneys during acute injury and reduce the damage that occurs during a heart attack.
Several clinical trials are underway designed to allow these exciting developments to be used to treat patients. As the researchers state, “Extensive research and clinical trials are currently underway for the use of MSCs as regenerative agents in many diseases including spinal cord injury, multiple sclerosis, Alzheimer’s disease, liver cirrhosis and hepatitis, osteoarthritis, myocardial infarction, kidney disease, inflammatory bowel disease, diabetes mellitus, knee cartilage injuries, organ transplantation, and graft-versus-host disease.” We can reasonably expect that exosomes will be used to treat at least some of these conditions in the very near future.
Reference: Rani al. (2015). Mesenchymal Stem Cell-derived Extracellular Vesicles: Toward Cell-free Therapeutic Applications. Molecular Therapy. 2015 May; 23(5): 812–823.
Tissue injury is common to many human diseases. Cirrhosis results in damaged, fibrotic liver tissue. Idiopathic pulmonary fibrosis and related lung diseases cause damage to lung tissue. A heart attack damages heart tissue, just as a stroke damages brain tissue. In some cases, such as minor tissue injury, the damaged tissue can repair itself. Over time, however, tissue damage becomes too great and the organ itself can fail. For example, long-standing cirrhosis can cause liver failure.
One area of active research is to find ways to protect tissue from injury or, if an injury occurs, to help the tissue repair itself before the damage becomes permanent and irreversible. Indeed, tissue repair is one of the main focuses of regenerative medicine. Likewise, one of the most promising approaches in the field of regenerative medicine is stem cell therapy. Researchers are learning that when it comes to protecting against tissue injury and promoting tissue repair, exosomes harvested from stem cells are perhaps the most attractive potential therapeutic.
Why are stem cell exosomes so promising? Exosomes are small packets of molecules that stem cells release to help the cells around them grow and flourish. While one could inject stem cells as a treatment for diseases (and they certainly do work for that purpose) it may be more effective in some cases to inject exosomes directly. So instead of relying on the stem cells to produce exosomes once they are injected into the body, stem cells can create substantial amounts of exosomes in the laboratory. Exosomes with desired properties could be concentrated and safely injected in large quantities, resulting in a potentially more potent treatment for the disease.
Indeed, researchers have shown that extracellular vesicles (exosomes and their cousins, microvesicles) can be collected from stem cells and used to treat a variety of tissue injuries in laboratory animals.
Just a few examples of this research:
- Exosomes from umbilical cord-derived mesenchymal stem cells were able to accelerate skin damage repair in rats who had suffered skin burns.
- Exosomes from the same type of stem cell protected the lungs and reduced lung blood pressure in mice with pulmonary hypertension.
- Exosomes from endothelial progenitor cells protected the kidney from damage caused by a lack of blood flow to the organ.
In this growing field of Regenerative Medicine, research is constant and building as new science evolves from stem cell studies. Researchers are closing in on the specific exosomes that may be helpful in treating human diseases caused by tissue injury.
Reference: Zhang et al. (2016). Focus on Extracellular Vesicles: Therapeutic Potential of Stem Cell-Derived Extracellular Vesicles. International Journal of Molecular Sciences. 2016 Feb; 17(2): 174.