Hematopoietic stem cell transplantation for severe rheumatoid arthritis

Translation of cell therapies to treat autoimmune disorders

Autoimmune diseases are a diverse and complex set of chronic disorders with a substantial impact on patient quality of life and a significant global healthcare burden. Current approaches to autoimmune disease treatment comprise broadly acting immunosuppressive drugs that lack disease specificity, possess limited efficacy, and confer undesirable side effects. Additionally, there are limited treatments available to restore organs and tissues damaged during the course of autoimmune disease progression. Cell therapies are an emergent area of therapeutics with the potential to address both autoimmune disease immune dysfunction as well as autoimmune disease-damaged tissue and organ systems. In this review, we discuss the pathogenesis of common autoimmune disorders and the state-of-the-art in cell therapy approaches to (1) regenerate or replace autoimmune disease-damaged tissue and (2) eliminate pathological immune responses in autoimmunity. Finally, we discuss critical considerations for the translation of cell products to the clinic.

The Outcome of Stem Cell-Based Therapies on the Immune Responses in Rheumatoid Arthritis

Rheumatoid arthritis as a common autoimmune inflammatory disorder with unknown etiology can affect 0.5-1% of adults in developed countries. It involves more than just the patient's joints and can be accompanied by several comorbidities and affect cardiovascular, pulmonary, and some other systems of the human body. Although cytokine-mediated pathways are mentioned to have a central role in RA pathogenesis, adaptive and innate immune systems and intracellular signaling pathways all have important roles in this process. Non-steroidal anti-inflammatory drugs, glucocorticoids, conventional disease-modifying anti-rheumatic drugs, and biological agents are some mentioned medications used for RA. They are accompanied by some adverse effects and treatment failures which elucidates the needing for novel and more powerful therapeutic approaches. Stem cell-based therapies and their beneficial effects on therapeutic processes of different diseases have been founded so far. They can be an alternative and promising therapeutic approach for RA, too; due to their effects on immune responses of the disease. This review, besides some explanations about RA characteristics, addresses the outcome of the stem cell-based therapies including mesenchymal stem cell transplantation and hematopoietic stem cell transplantation for RA and explains their effects on the disease improvement.

Suppression of proteoglycan-induced autoimmune arthritis by myeloid-derived suppressor cells generated in vitro from murine bone marrow

Background

Myeloid-derived suppressor cells (MDSCs) are innate immune cells capable of suppressing T-cell responses. We previously reported the presence of MDSCs with a granulocytic phenotype in the synovial fluid (SF) of mice with proteoglycan (PG)-induced arthritis (PGIA), a T cell-dependent autoimmune model of rheumatoid arthritis (RA). However, the limited amount of SF-MDSCs precluded investigations into their therapeutic potential. The goals of this study were to develop an in vitro method for generating MDSCs similar to those found in SF and to reveal the therapeutic effect of such cells in PGIA.

Methods

Murine bone marrow (BM) cells were cultured for 3 days in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF). The phenotype of cultured cells was analyzed using flow cytometry, microscopy, and biochemical methods. The suppressor activity of BM-MDSCs was tested upon co-culture with activated T cells. To investigate the therapeutic potential of BM-MDSCs, the cells were injected into SCID mice at the early stage of adoptively transferred PGIA, and their effects on the clinical course of arthritis and PG-specific immune responses were determined.

Results

BM cells cultured in the presence of GM-CSF, IL-6, and G-CSF became enriched in MDSC-like cells that showed greater phenotypic heterogeneity than MDSCs present in SF. BM-MDSCs profoundly inhibited both antigen-specific and polyclonal T-cell proliferation primarily via production of nitric oxide. Injection of BM-MDSCs into mice with PGIA ameliorated arthritis and reduced PG-specific T-cell responses and serum antibody levels.

Conclusions

Our in vitro enrichment strategy provides a SF-like, but controlled microenvironment for converting BM myeloid precursors into MDSCs that potently suppress both T-cell responses and the progression of arthritis in a mouse model of RA. Our results also suggest that enrichment of BM in MDSCs could improve the therapeutic efficacy of BM transplantation in RA.

[Current value of stem-cell transplantation in autoimmune diseases]

Transplantations of autologous or allogeneic stem cells from bone marrow or peripheral blood are preformed for the treatment of resistant autoimmune diseases. Data have been systematically collected since 1996. We describe the historical development of this procedure for autoimmune diseases, the possible mechanisms of action, the options for stem cell collection, purging and conditioning (high-dose chemotherapy, combination with monoclonal anti-T- or B-cell antibodies, total body irradiation), as well as the reported outcomes in the literature.

The role of immune ablation and stem cell transplantation in severe SLE

High-dose immunosuppression followed by autologous hematopoietic stem cell therapy (HSCT) has the promise of long-term response after a short, intense period of immunosuppressive therapy but it is associated with an increased risk of serious short-term complications. HSCT induces major clinical responses in about 65% of patients with SLE who failed standard therapies. In some of these patients such responses are durable for at least several years, but the curative potential of this procedure in severe SLE is still unknown. Procedure-related mortality varies among studies between 5 and 12% and seems to be lower in relatively larger single center studies. Until more reliable estimates of the actual risks and long-term outcomes become available, patients with potentially life-threatening or disabling major organ involvement who are in acceptable general medical condition should be considered for autologous HSCT if they have failed a reasonable course of standard immunosuppressive therapy. To accomplish the best therapeutic and scientific results, it is necessary to treat all patients in carefully planned protocols by specialized teams of lupus specialists and transplanters. All immunoablative protocols should incorporate carefully planned studies of immune reconstitution to understand the mechanisms of cure or failure.

Aggressive multiple sclerosis—is there a role for stem cell transplantation?

Conventional drugs, including disease-modifying drugs, various cytostatic regimens and steroids, are unable to control disease activity in a small group of patients with "malignant" multiple sclerosis (MS). This group of patients could be offered aggressive therapies, such as high-dose immunosuppression followed by haematopoietic stem cell transplant (HSCT). Bone marrow or peripheral blood HSCT has been proposed for the treatment of autoimmune diseases because of its immunosuppressive and immunomodulatory effects, and recapitulation of lymphocyte ontogeny may stabilise or improve the course of MS in some patients. There have been a few small studies conducted using high-dose immunoablation and HSCT. A recent clinical trial of 85 patients treated by HSCT revealed that more than 60% of patients may benefit from this procedure. Due to the perceived risks associated with HSCT, only patients with malignant MS who no longer benefit from more conventional therapies were enrolled. HSCT is thus a justified and feasible treatment in certain patient groups, although transplant-related mortality must be reduced.

Haematopoietic stem cell transplantation for autoimmune disorders: the American perspective

The hypothesis that haematopoietic stem cell transplantation (HSCT) might be useful in treating refractory autoimmune diseases (AID) was suggested by studies in animal models and by the improvement of concurrent autoimmune diseases in patients who had undergone transplantation for haematological disorders. This concept has now been tested in a substantial number of phase I/II clinical trials of autologous HSCT. These early results are promising, even in patients who have failed on multiple standard therapies for AID. Transplantation-related toxicity has decreased with growing experience in the application of this procedure, better patient selection and the modification of treatment protocols. Randomized trials currently under way or under consideration should clarify the role of HSCT in patients with autoimmune disorders.