Autoimmune disorders are conditions in which the sufferer’s body produces substances that attack the healthy cells of the organism, as it doesn’t distinguish between the healthy tissues and antigens. There are more than 80 types of autoimmune conditions known today, among which diabetes type 1, systemic lupus erythematosus, rheumatoid arthritis, celiac disease, myasthenia gravis and multiple sclerosis.
The exact cause of these ailments is unknown, but scientists believe that viruses, bacteria or certain drugs may trigger some internal changes that confuse the organism and cause the immune system to react by destroying the healthy tissues. Besides the damage caused to healthy cells, autoimmune conditions also lead to changes in organ function and may cause the abnormal growth of organs.
These disorders may affect several tissues or organs, but the most common areas that are destroyed by the immune system include the red blood cells, skin, connective tissues, blood vessels, endocrine glands (mostly the pancreas and thyroid), joints and muscles.
Currently, the standard treatment for autoimmune conditions is represented by immune suppressive agents, but these medications only induce temporary improvements, and don’t cure the disorders completely. For this reason, scientists have started to investigate the potential use of stem cells in autoimmune disorders.
In animal studies, stem cell therapy with mesenchymal stem cells has been shown to induce healing activity in various autoimmune disorders, and to prevent the destruction of healthy tissues by the immune system. But what does research say about treating autoimmune disorders in humans? Are stem cells effective in this case as well?
THE USE OF STEM CELLS IN AUTOIMMUNE DISORDERS IN HUMANS
Mesenchymal stromal stem cells have been found to exert immunological functions under inflammatory conditions, a study published by researchers at the Department of Internal Medicine, Erasmus MC, Rotterdam in Arthritis Research and Therapy showing that MSCs play an important role in maintaining immune homeostasis [1].
According to researchers, MSCs do not have immune cell effector functions and are not “true” immune cells, but can play a role in the initiation of immune responses. Unlike immune T- and B-cells, mesenchymal stem cells do not poses receptors for recognizing the antigens, but they do express pattern recognition receptors, which enable the stem cells to recognize microbes.
In conclusion, the mentioned study showed that although MSCs do not fit the exact definition of immune cells, they do influence the body’s immune response and can act as regulators or coordinators of the immune system [1].
In another paper published in the Nature journal, scientists at the Massachusetts General Hospital, Harvard Medical School have showed that hematopoietic stem cells may be used in treating severe autoimmune diseases, like rheumatoid arthritis or multiple sclerosis [2].
The stem cell therapy investigated by the US researchers involved the transplantation of HSC following an immunosuppressive treatment like chemotherapy or radiotherapy. This treatment was found to be effective in curing autoimmune diseases in animal models, and most patients who received allo-HCT achieved remission of the disorder, although there were also exceptions.
Researchers at the Stem Cell Technology Research Center, Tehran have investigated the use of stem cell therapy in multiple sclerosis patients. Their review paper, published in the International Journal of Hematology-Oncology and Stem Cell Research, showed the following: neural stem cells derived from the adult central nervous system may have neuroprotective and immunomodulatory effects, so they may be a solution for treating MS [3].
Mesenchymal stem cells derived from bone marrow also have a potential for migration into the inflamed tissues of the central nervous system and are able to differentiate into neuronal cells. In mice, MSCs helped in improving the neurological function of animals with experimental autoimmune encephalomyelitis (EAE). The application of stem cells in humans with multiple sclerosis was also investigated by scientists at the American University of Beirut Medical Center, Lebanon, who showed that bone marrow mesenchymal stem cells may lead to clinical improvements in patients with advanced multiple sclerosis [4].
Another autoimmune condition in which stem cells may be useful is rheumatoid arthritis, studies showing that human amnion mesenchymal cells isolated from the placenta may be feasible for treating collagen-induced arthritis in rats [5]. These cells have immunosuppressive functions and can ameliorate the severity of arthritis, so they may be a promising therapy for RA sufferers.
Despite these positive results, there are still a lot of challenges to overcome when it comes to treating autoimmune disorders with stem cells, so scientists need to establish precise protocols for all these conditions that could be treated through stem cells therapy.
References:
[1] http://www.arthritis-research.com/content/17/1/88
[2] http://www.nature.com/nature/journal/v435/n7042/full/nature03728.html
[3] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3913133/
[4] http://www.ncbi.nlm.nih.gov/pubmed/20728948
[5] http://www.ncbi.nlm.nih.gov/pubmed/25962385