Juvenile arthritis (JA) is a term covering a heterogeneous group of diseases of the immune system that cause painful swelling the joints, typically lasting more than six weeks, in children ages 16 and under.

The inflammation or swelling is the result of an autoimmune response, in which a person’s immune system — instead of helping to fight infection and threats — attacks healthy cells lining the insides of joints. The autoimmune response sometimes also targets cells in the eyes, skin, muscles, and gastrointestinal tract.

Currently, there is no cure for JA and available treatments aim to alleviate pain or prevent joint deterioration.

Stem cell therapy may be a promising treatment option for JA patients whose disease is resistant to medication, and for those who have severe and debilitating disease. But the approach is still in relatively early stages for many diseases, including juvenile arthritis.

What are stem cells

Stem cells or “blank slate” cells — unspecialized cells — have the ability to develop into distinct and specialized cells. Researchers working in a laboratory direct the maturation, or  specialization, of stem cell lines.

There are different types of stem cells.  Pluripotent stem cells (PSC) are also called master stem cells because they can potentially give rise — to differentiate or mature — into all of the main cell types found in a person: skin cells, bone cells, gastrointestinal and respiratory system cells, etc.  PSCs can be derived from embryos or unfertilized eggs (embryonic stem cells) or they can be made from a patient’s own cells, genetically reprogrammed though the introduction of genes, in what  is known as induced pluripotent cells.

Mesenchymal stem cells (MSCs) are known as “adult” stem cells, as they are generally found in the bone marrow of a patient, although research also suggests they may also be in tissues like that of fat and muscle. Mesenchymal stem cells can be differentiated to make the various specialized cells of skeletal tissues: cartilage cells (chondrocytes), bone cells (osteoblasts), and fat cells (adipocytes).

Hematopoietic stem cells (HSC) or blood stem cells, are immature cells also found in the bone marrow or peripheral (circulating) blood that give rise to all blood cells: red and white blood cells, and platelets.

Stem cells derived from a patient are called autologous stem cells, while those derived from a donor — usually closely matched — are called allogeneic stem cells. Autologous stem cells have the advantage of being less likely to be rejected by the body.

Stem cell therapy

Stem cell therapy consists of using stems cells to replace or repair the cells of damaged organs and tissues, so as treat patients with a given disease or condition. They are unspecialized cells capable of renewing themselves through cell division that can be induced, under certain conditions, to become tissue- or organ-specific cells with special functions.

After being collected from the patient, for instance, autologous stem cells are grown in the laboratory and manipulated to specialize into specific types of cells, such as bone cells, heart muscle cells, blood cells, or nerve cells. These specialized cells are then injected back into a patient. Once injected, the healthy transplanted cells follow inflammatory signals from the damaged tissues and may contribute to repairing the tissue.

Stem cell studies in JA

The first autologous stem cell transplant procedure (ASCT) to treat JA was performed in 1997. Between 1997 and 2001, 23 children with progressive refractory JA were enrolled in a Phase 2 clinical trial ASCT. The long-term outcomes of the treatment on 20 patients were assessed and published in 2007.

The children were followed up over a median period of 80 months. One patient withdrew from the trial and two died of macrophage activation syndrome (MAS), possibly caused by  infections that followed the transplant. Of the remaining 20 patients, eight reached complete remission (remaining disease-free throughout the follow-up period), seven attained partial response, and five failed to respond to treatment. (after two to 16 months in 11 patients, and after seven years in one patient). Of these 12 patients, 11 relapsed within 2- to 16-months post-treatment, and one seven years later. Two of these five non-responders later died of infections as a result of immunosuppression given for re-treatment.

Although favorable responses — “long-lasting improvement” — were seen in a number of children, the procedure was associated with a significant risk of morbidity and death. The study recommended this approach be reserved for “patients with severe progressive disease” and, because of the current availability of biologic treatments, for children who fail at such prior treatments.

A clinical trial (NTR4146) testing the effect of MSC transplantation for the treatment of drug-resistant JA is currently ongoing at University Medical Center Utrecht in the Netherlands.

A study designed to explore the therapeutic effect of umbilical cord mesenchymal stem cells (UC-MSCs) for the treatment of JA was published in 2016. Ten children with JA, ages 2 to 15, were treated with UC-MSCs and received a second infusion three months later. Results suggested that UC-MSCs can reduce inflammation, improve immune tolerance, and effectively alleviate disease symptoms. Its authors concluded that UC-MSCs “might provide a safe and novel approach” for treating juvenile arthritis.

The treatment’s long-term effects, however, are yet to be determined.

Note: Juvenile Arthritis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.

Ana holds a PhD in Immunology from the University of Lisbon and worked as a postdoctoral researcher at Instituto de Medicina Molecular (iMM) in Lisbon, Portugal. She graduated with a BSc in Genetics from the University of Newcastle and received a Masters in Biomolecular Archaeology from the University of Manchester, England. After leaving the lab to pursue a career in Science Communication, she served as the Director of Science Communication at iMM.
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Ana holds a PhD in Immunology from the University of Lisbon and worked as a postdoctoral researcher at Instituto de Medicina Molecular (iMM) in Lisbon, Portugal. She graduated with a BSc in Genetics from the University of Newcastle and received a Masters in Biomolecular Archaeology from the University of Manchester, England. After leaving the lab to pursue a career in Science Communication, she served as the Director of Science Communication at iMM.
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