Preclinical experiments

Stem Cell Therapies for Progressive Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system characterized by demyelination and axonal degeneration. MS patients typically present with a relapsing-remitting (RR) disease course, manifesting as sporadic attacks of neurological symptoms including ataxia, fatigue, and sensory impairment. While there are several effective disease-modifying therapies able to address the inflammatory relapses associated with RRMS, most patients will inevitably advance to a progressive disease course marked by a gradual and irreversible accrual of disabilities. Therapeutic intervention in progressive MS (PMS) suffers from a lack of well-characterized biological targets and, hence, a dearth of successful drugs. The few medications approved for the treatment of PMS are typically limited in their efficacy to active forms of the disease, have little impact on slowing degeneration, and fail to promote repair. In looking to address these unmet needs, the multifactorial therapeutic benefits of stem cell therapies are particularly compelling. Ostensibly providing neurotrophic support, immunomodulation and cell replacement, stem cell transplantation holds substantial promise in combatting the complex pathology of chronic neuroinflammation. Herein, we explore the current state of preclinical and clinical evidence supporting the use of stem cells in treating PMS and we discuss prospective hurdles impeding their translation into revolutionary regenerative medicines.

Bone Marrow Transfer in Relapsing-Remitting EAE Ameliorates Disease at First Remission, with No Synergistic Effect upon Co-Transplantation with Mesenchymal Stem Cells

Multiple sclerosis (MS) is a neurological disorder characterized by an autoimmune response, demyelinating plaques and axonal damage. Intense immunosuppression (II) followed by autologous hematopoietic stem cell transplantation has been proposed as a treatment in severe forms of MS. We have used murine relapsing-remitting (RR) experimental autoimmune encephalomyelitis (RR-EAE) to evaluate the transplantation of syngeneic bone marrow cells (BMC) after II, in combination with mesenchymal stem cells (MSCs) as a new therapeutic adjunct capable of improving immune reconstitution. In EAE-affected mice treated with BMC alone, we observed a drastic reduction in the clinical course only during the early RR phase of the disease. There was no difference in the RR-EAE clinical course between mice treated with BMC alone and co-transplanted mice. To analyze the immune reconstitution, we quantified the circulating immune cells in naïve and RR-EAE-affected mice after II, with BMC alone or in combination with MSC. Although II resulted in reduced numbers of circulating immune cells, reconstitution did not differ in co-transplanted mice. During the early phase of the disease, IL-4 was significantly elevated in co-transplanted mice, as compared to those treated with BMC alone. These data suggest that BMC transplantation after II transiently ameliorates the clinical symptoms of RR-EAE, but that co-transplantation with MSC has no synergistic effect.

Outcomes and Cost-Effectiveness of Autologous Hematopoietic Cell Transplant for Multiple Sclerosis

PURPOSE OF REVIEW

This review presents a critical appraisal of the use of autologous hematopoietic cell transplant (AHCT) for the treatment of multiple sclerosis. We present the reader with a brief review on the AHCT procedure, its immunomodulatory mechanism of action in MS, the most recent evidence in support of its use in patients with relapsing-remitting multiple sclerosis (RRMS), as well as its cost considerations.

RECENT FINDINGS

The first meta-analysis of clinical trials of AHCT for patients with MS demonstrated durable 5-year progression-free survival rates and low treatment-related mortality. Recently, the first randomized controlled phase III clinical trial demonstrated AHCT to be superior to best available therapy for a subset of patients with RRMS. This led to the American society for transplant and cellular therapies (ASTCT) to recommend AHCT "for patients with relapsing forms of MS who have prognostic factors that indicate a high risk of future disability." AHCT should be considered for patients with RRMS with evidence of clinical activity who have failed 2 lines of therapy or at least one highly active disease-modifying therapy.

Regenerating Immunotolerance in Multiple Sclerosis with Autologous Hematopoietic Stem Cell Transplant

Multiple sclerosis (MS) is an inflammatory disorder of the central nervous system where evidence implicates an aberrant adaptive immune response in the accrual of neurological disability. The inflammatory phase of the disease responds to immunomodulation to varying degrees of efficacy; however, no therapy has been proven to arrest progression of disability. Recently, more intensive therapies, including immunoablation with autologous hematopoietic stem cell transplantation (AHSCT), have been offered as a treatment option to retard inflammatory disease, prior to patients becoming irreversibly disabled. Empirical clinical observations support the notion that the immune reconstitution (IR) that occurs following AHSCT is associated with a sustained therapeutic benefit; however, neither the pathogenesis of MS nor the mechanism by which AHSCT results in a therapeutic benefit has been clearly delineated. Although the antigenic target of the aberrant immune response in MS is not defined, accumulated data suggest that IR following AHSCT results in an immunotolerant state through deletion of pathogenic clones by a combination of direct ablation and induction of a lymphopenic state driving replicative senescence and clonal attrition. Restoration of immunoregulation is evidenced by changes in regulatory T cell populations following AHSCT and normalization of genetic signatures of immune homeostasis. Furthermore, some evidence exists that AHSCT may induce a rebooting of thymic function and regeneration of a diversified naïve T cell repertoire equipped to appropriately modulate the immune system in response to future antigenic challenge. In this review, we discuss the immunological mechanisms of IR therapies, focusing on AHSCT, as a means of recalibrating the dysfunctional immune response observed in MS.

Intense immunosuppression followed by autologous haematopoietic stem cell transplantation as a therapeutic strategy in aggressive forms of multiple sclerosis

In the majority of relapsing multiple sclerosis patients, the disease can be quite easily controlled by already available, approved therapies. There are, however, some aggressive cases who continue to have clinical and magnetic resonance imaging (MRI) activity in spite of the treatment. These are the cases who may now receive benefit from intense immunosuppression followed by autologous haematopoietic stem cell transplantation (aHSCT). In this review, we describe the method and the rationale of aHSCT, the more recently published studies that demonstrate its efficacy in selected multiple sclerosis cases, the problems related to safety and the transplant-related mortality risk of the procedure. A description of the ideal patient who can take advantage of aHSCT is outlined and, finally, the ongoing studies which are near to completion or are close to starting are briefly reported.

Hematopoietic stem cell transplantation for multiple sclerosis: is it a clinical reality?

Hematopoietic stem cell transplantation (HSCT) is a treatment paradigm that has long been utilized for cancers of the blood and bone marrow but has gained some traction as a treatment paradigm for multiple sclerosis (MS). Success in the treatment of patients with this approach has been reported primarily when strict inclusion criteria are imposed that have eventuated a more precise understanding of MS pathophysiology, thereby governing trial design. Moreover, enhancing the yield and purity of hematopoietic stem cells during isolation along with the utility of appropriate conditioning agents has provided a clearer foundation for clinical translation studies. To support this approach, preclinical data derived from animal models of MS, experimental autoimmune encephalomyelitis, have provided clear identification of multipotent stem cells that can reconstitute the immune system to override the autoimmune attack of the central nervous system. In this review, we will discuss the rationale of HSCT to treat MS by providing the benefits and complications of the clinically relevant protocols, the varying graft types, and conditioning regimens. However, we emphasize that future trials based on HSCT should be focused on specific therapeutic strategies to target and limit ongoing neurodegeneration and demyelination in progressive MS, in the hope that such treatment may serve a greater catchment of patient cohorts with potentially enhanced efficiency and lower toxicity. Despite these future ambitions, a proposed international multicenter, randomized clinical trial of HSCT should be governed by the best standard care of treatment, whereby MS patients are selected upon strict clinical course criteria and long-term follow-up studies of patients from international registries are imposed to advocate HSCT as a therapeutic option in the management of MS.

The hematopoietic system in the context of regenerative medicine

Hematopoietic stem cells (HSC) represent the prototype stem cell within the body. Since their discovery, HSC have been the focus of intensive research, and have proven invaluable clinically to restore hematopoiesis following inadvertent radiation exposure and following radio/chemotherapy to eliminate hematologic tumors. While they were originally discovered in the bone marrow, HSC can also be isolated from umbilical cord blood and can be "mobilized" peripheral blood, making them readily available in relatively large quantities. While their ability to repopulate the entire hematopoietic system would already guarantee HSC a valuable place in regenerative medicine, the finding that hematopoietic chimerism can induce immunological tolerance to solid organs and correct autoimmune diseases has dramatically broadened their clinical utility. The demonstration that these cells, through a variety of mechanisms, can also promote repair/regeneration of non-hematopoietic tissues as diverse as liver, heart, and brain has further increased their clinical value. The goal of this review is to provide the reader with a brief glimpse into the remarkable potential HSC possess, and to highlight their tremendous value as therapeutics in regenerative medicine.

Treatment of refractory ITP and Evans syndrome by haematopoietic cell transplantation: is it indicated, and for whom?

Several lines of therapy have been established for patients with immune thrombocytopenia (ITP) and Evans syndrome. However, these therapies generally require prolonged administration, lead to profound immunosuppression and increased infectious risk, and are often poorly tolerated. While most patients with these disorders will respond to first-line steroid therapy, others will prove refractory or intolerant to multiple treatments. In these patients (and possibly even selected patients who are not considered refractory), autologous or allogeneic haematopoietic stem cell transplantation (HCT) may provide definitive therapy. We review the literature on the treatment of ITP and Evans syndrome with HCT and discuss its use in the management of these disorders. We also pose, for the purpose of discussion, research questions that will be important to address if HCT is to be considered a viable option for more patients with these diseases.

Low intensity lympho-ablative regimen followed by autologous hematopoietic stem cell transplantation in severe forms of multiple sclerosis: A MRI-based clinical study

BACKGROUND

Autologous hematopoietic stem cell transplantation (AHSCT) has been successfully used to treat aggressive forms of multiple sclerosis (MS) that are unresponsive to approved therapies. In the last years, in view of the risk of mortality related to the procedure, the utilization of low-intensity conditioning regimens has been considered.

OBJECTIVE

To report magnetic resonance imaging (MRI) and clinical data in a small cohort of patients treated with a low-intensity lympho-ablative regimen, followed by AHSCT.

METHODS

Seven patients affected by relapsing-remitting MS (RRMS) underwent AHSCT, with cyclophosphamide 120 mg/kg in 2 days as the conditioning regimen; and were then followed with serial MRI evaluations until 36 months, with clinical evaluations until 60 months.

RESULTS

The mean number of gadolinium (Gd)-enhancing lesions significantly decreased after treatment, but a complete suppression of inflammatory activity was not obtained. No deaths occurred, but every patient developed adverse events, although not severe. After 5 years of follow-up, two patients remained stable, one patient markedly improved and four patients had a mild progression of the disease. Only one patient experienced a relapse after treatment.

CONCLUSION

A low-intensity conditioning regimen with AHSCT has a profound effect on MRI inflammation and relapses, but is not able to completely abrogate MRI activity and disease progression of aggressive RRMS.

Stem cell transplantation in systemic sclerosis

PURPOSE OF REVIEW

The purpose of this review is to discuss recent published clinical and mechanistic studies on stem cell transplantation for systemic sclerosis and their implications for clinical practice.

RECENT FINDINGS

Retrospective analyses of independent cohorts of systemic sclerosis patients treated with autologous stem cell transplantation showed significant improvement of skin thickening, lung function and quality of life, but at the expense of 6-17% treatment-related mortality. Right heart catheterization was employed in one study to identify and exclude patients at risk of serious cardiopulmonary toxicity. The superior efficacy of stem cell transplantation versus intravenous pulses cyclophosphamide was demonstrated in a small randomized, controlled phase 2 trial in 19 systemic sclerosis patients and a large randomized phase 3 trial in 156 patients with severe diffuse cutaneous systemic sclerosis. The latter also showed a survival benefit of transplanted patients despite a 10% transplant-related mortality. Mechanistic studies in transplanted patients have shown major shifts in circulating natural killer cells, T and B lymphocytes immediately after stem cell transplantation, similar to those observed in other autoimmune conditions. Stem cell transplantation of systemic sclerosis patients with lung involvement resulted in demonstrable attenuation of thoracic high-resolution CT (HRCT) abnormalities and serum markers of lung fibrosis.

SUMMARY

Stem cell transplantation is an effective treatment option for patients with severe systemic sclerosis, but is associated with toxicity and treatment-related mortality. The available data suggest that patient selection and comprehensive cardiopulmonary screening are critical factors in determining outcome.

VIDEO ABSTRACT AVAILABLE

See the Supplementary Digital content 1 (http://links.lww.com/COR/A7).

Hematopoietic stem cell transplantation for systemic lupus erythematosus

Two streams of research are at the origin of the utilization of hematopoietic stem cell transplantation (HSCT) for severe autoimmune diseases (SADs). The allogeneic approach came from experimental studies on lupus mice, besides clinical results in coincidental diseases. The autologous procedure was encouraged by researches on experimental neurological and rheumatic disorders. At present the number of allogeneic HSCT performed for human SADs can be estimated to not over 100 patients, and the results are not greatly encouraging, considering the significant transplant-related mortality (TRM) and the occasional development of a new autoimmune disorder and/or relapses notwithstanding full donor chimerism. Autologous HSCT for refractory SLE has become a major target. Severe cases have been salvaged, TRM is low and diminishing, and prolonged clinical remissions are obtainable. Two types of immune resetting have been established, "re-education" and regulatory T cell (Tregs) normalization. Allogeneic HSCT for SLE seems best indicated for patients with disease complicated by an oncohematologic malignancy. Autologous HSCT is a powerful salvage therapy for otherwise intractable SLE. The duration of remission in uncertain, but a favorable response to previously inactive treatments is a generally constant feature. The comparison with new biological agents, or the combination of both, are to be ascertained.

Haematopoietic SCT in severe autoimmune diseases: updated guidelines of the European Group for Blood and Marrow Transplantation

In 1997, the first consensus guidelines for haematopoietic SCT (HSCT) in autoimmune diseases (ADs) were published, while an international coordinated clinical programme was launched. These guidelines provided broad principles for the field over the following decade and were accompanied by comprehensive data collection in the European Group for Blood and Marrow Transplantation (EBMT) AD Registry. Subsequently, retrospective analyses and prospective phase I/II studies generated evidence to support the feasibility, safety and efficacy of HSCT in several types of severe, treatment-resistant ADs, which became the basis for larger-scale phase II and III studies. In parallel, there has also been an era of immense progress in biological therapy in ADs. The aim of this document is to provide revised and updated guidelines for both the current application and future development of HSCT in ADs in relation to the benefits, risks and health economic considerations of other modern treatments. Patient safety considerations are central to guidance on patient selection and HSCT procedural aspects within appropriately experienced and Joint Accreditation Committee of International Society for Cellular Therapy and EBMT accredited centres. A need for prospective interventional and non-interventional studies, where feasible, along with systematic data reporting, in accordance with EBMT policies and procedures, is emphasized.

Stem cells in the treatment of inflammatory arthritis

Autologous haematopoietic stem cell transplantation in patients with rheumatoid arthritis (RA) resulted in a positive short-term outcome clinically with low treatment-related toxicity. However, early conditioning regimens were of low immunoablative intensity and most patients relapsed. Mechanistic studies suggest that residual lesional effector cells may have been responsible for the relapses. The introduction of biopharmaceuticals has, for the moment, reduced the need for further experimental studies. Juvenile idiopathic arthritis patients, mostly of the systemic subgroup, have shown nearly 33% durable drug-free remission, but with significant toxicity, including fatal macrophage-activation syndrome early in the programme. Later modifications to the protocol have reduced this toxicity. Mesenchymal stem cells (MSCs), derived from several sources including bone marrow and adipose tissue, are being tested as tissue-regenerative and immunomodulating agents in many autoimmune diseases and animal models of inflammatory arthritis have been positive. MSCs and other stromal cells derived from actively inflamed synovium and peripheral blood of RA patients do not always demonstrate a full range of differentiation potential compared with healthy MSCs, although their immunomodulalatory capacity is unimpaired.

Hematopoietic SCT for the treatment of multiple sclerosis

Multiple sclerosis (MS) is the leading autoimmune indication for autologous hematopoietic SCT (aHSCT). Patient selection criteria and transplant interventions have been refined through a series of cohort and registry studies. High- and low-intensity chemotherapy-based conditioning regimens have been used, creating trade-offs between toxicity and effectiveness. TBI has been associated with greater toxicity and poor outcomes. aHSCT stops MS relapses and lessens the disability in malignant MS, which otherwise rapidly incapacitates patients. Better responses occur in progressive MS earlier in the disease when it has a more inflammatory nature. aHSCT prevents further disability in many patients, but some actually recover from their infirmities. Current regimens and supportive care result in very low morbidity and mortality. MS patients experience unique complications in addition to the expected toxicities. Cytokines used alone for stem-cell mobilization may induce MS flares but are safe to be used in combination with steroids or cytotoxic agents. Urinary tract infections, herpes virus reactivation and an engraftment syndrome may occur early after aHSCT. Rarely secondary autoimmune diseases have been reported late after HSCT. Increasing experience in caring for patients with MS has reduced the frequency and severity of toxicity. Conceived as an opportunity to 'reboot' a tolerant immune system, aHSCT is successful in treating patients with MS that is refractory to conventional immunomodulatory drugs.

High-dose immunoablation with autologous haematopoietic stem cell transplantation in aggressive multiple sclerosis: a single centre 10-year experience

There are multiple sclerosis patients who suffer from an aggressive course of the disease with severe relapses and rapid accumulation of disability despite adequate treatment. In such cases high-dose immunoablation with autologous haematopoietic stem cell transplantation (ASCT) may be considered. Our objective was to report our experience with 26 multiple sclerosis patients treated with ASCT within the years 1998-2008. Twenty-six patients (Expanded Disability Status Scale 2.5-7.5 (median 6.0), multiple sclerosis duration 2-19 years (median 7)) with aggressive multiple sclerosis underwent autologous haematopoietic stem cell transplantation. Stem cells were mobilized by high-dose cyclophosphamide and granulocyte colony-stimulating factor, BEAM (carmustine, etoposide, cytarabine, melphalan) was used for immunoablation. Patients were evaluated at baseline and every six months post ASCT for adverse events and clinical outcome. Follow-up period was 11-132 months (median 66). Progression-free survival was calculated using the Kaplan- Meier method. At 3 and 6 years of follow-up 70.8% and 29.2% of patients respectively were free of progression. Patients with relapsing multiple sclerosis course, disease duration <5 years and age <35 years had a more favourable outcome. There was no death within 100 days after ASCT. We conclude that ASCT represents a viable and effective treatment option for aggressive multiple sclerosis.

Hematopoietic SCT modulates gut inflammation in experimental inflammatory bowel disease

Hematopoietic SCT (HSCT) and high-dose chemotherapy are being explored as therapy for various human refractory immune-mediated conditions, including inflammatory bowel diseases (IBD). Nevertheless, the exact immunological mechanisms by which the BM cells (BMCs) or immunosuppression provide remission from these diseases is not yet clear. In this work, we investigated the role of these therapies in the modulation of gut mucosal inflammation in an experimental model of IBD. Colitis was induced in mice by 2,4,6-trinitrobenzenesulfonic acid and after CY was administered (200 mg/kg) alone (CY group) or followed by BMCs infusion (HSCT group). Animals were followed for 60 days. Both HSCT and CY reduced the histopathological features of colitis significantly. Infused cells were localized in the gut, and a marked decrease of CD4(+) leukocytes in the inflammatory infiltrate on days +7 and +14 and of CD8(+) cells on day +7 was found in both treatments allied to impressive reduction of proinflammatory Th1 and Th17 cytokines. Although chemotherapy alone was the best treatment regarding the induction of immunosuppressive molecules, only HSCT resulted in increased survival rates compared with the control group. Our findings indicate that high-dose CY followed by HSCT is effective in the modulation of mucosal immunity and in accelerating immune reconstitution after BMT, thus providing valuable tools to support the development and understanding of novel therapeutic strategies for IBD.

Hematopoietic stem cell transplantation for systemic lupus erythematosus, the antiphospholipid syndrome and bullous skin diseases

Systemic lupus erythematosus (SLE) is considered the paradigm of autoimmune diseases (AD), and the murine models are known to be curable by means of allogeneic hematopoietic stem cell transplantation (HSCT). However autologous transplantations were predominantly utilized in the clinic, starting from 1996, and by now well over 150 very severe patients have been transplanted worldwide. Transplant-related mortality (TRM) in 153 cases was 7%, with a wide center effect (from 0-2% to 13%). The disease arresting effect was dramatic even in patients on dialysis, although ASCT should not be considered a last resource, salvage therapy, but a disease- modifying intervention to be utilized in the early stages of patently aggressive disease. The autoimmune biological parameters are consistently modified, although some degree of ANA-positivity generally persists. Similar encouraging results have been obtained in the primary antiphospholipid syndrome (APS) and in bullous disorders of the skin.

Treatment of systemic sclerosis: potential role for stem cell transplantation

Hematopoietic stem cell transplantation may "reset" the immune reconstitution and induce self tolerance of autoreactive lymphocytes, and has been explored in the treatments for systemic sclerosis. Phase I/II trials have shown a satisfactory risk benefit ratio. The true benefit will be identified by two ongoing prospective, randomized phase III trials. Multipotent mesenchymal stromal cells (MSCs) possess antiproliferative, anti-inflammatory, and immunosuppressive properties. The use of MSCs has showed successful responses in patients with severe steroid-resistant acute graft versus host disease in phase II trials, and may be a potentially promising option for patients with systemic sclerosis.

Autologous hematopoietic stem cell transplantation for autoimmune diseases: an observational study on 12 years' experience from the European Group for Blood and Marrow Transplantation Working Party on Autoimmune Diseases

BACKGROUND

Autologous hematopoietic stem cell transplantation has been used since 1996 for the treatment of severe autoimmune diseases refractory to approved therapies. We evaluated the long-term outcomes of these transplants and aimed to identify potential prognostic factors.

DESIGN AND METHODS

In this observational study we analyzed all first autologous hematopoietic stem cell transplants for autoimmune diseases reported to the European Group for Blood and Marrow Transplantation (EBMT) registry between 1996-2007. The primary end-points for analysis were overall survival, progression-free survival and transplant-related mortality at 100 days.

RESULTS

Nine hundred patients with autoimmune diseases (64% female; median age, 35 years) who underwent a first autologous hematopoietic stem cell transplant were included. The main diseases were multiple sclerosis (n=345), systemic sclerosis (n=175), systemic lupus erythematosus (n=85), rheumatoid arthritis (n=89), juvenile arthritis (n=65), and hematologic immune cytopenia (n=37). Among all patients, the 5-year survival was 85% and the progression-free survival 43%, although the rates varied widely according to the type of autoimmune disease. By multivariate analysis, the 100-day transplant-related mortality was associated with the transplant centers' experience (P=0.003) and type of autoimmune disease (P=0.03). No significant influence of transplant technique was identified. Age less than 35 years (P=0.004), transplantation after 2000 (P=0.0015) and diagnosis (P=0.0007) were associated with progression-free survival.

CONCLUSIONS

This largest cohort studied worldwide shows that autologous hematopoietic stem cell transplantation can induce sustained remissions for more than 5 years in patients with severe autoimmune diseases refractory to conventional therapy. The type of autoimmune disease, rather than transplant technique, was the most relevant determinant of outcome. Results improved with time and were associated with the transplant centers' experience. These data support ongoing and planned phase III trials to evaluate the place of autologous hematopoietic stem cell transplantation in the treatment strategy for severe autoimmune diseases.

Cellular therapy of systemic lupus erythematosus

Immunoablation with autologous hematopoietic stem cell rescue has been used in over 1,300 autoimmune disease patients, around 150 with SLE. Some patients have experienced durable remissions with loss of autoantibodies, whereas others either did not respond or died as a result of the treatment. Prospective randomised trials are required and are being planned to establish the place for this potentailly curative strategy. Mesenchymal stem cells are in an exploratory phase for the treatment of acute autoimmune disease including SLE. The principle is that they home to inflammed tissue and exert an antiinflammatory paracrine effect.

Haematopoietic stem cell transplantation for autoimmune disorders

PURPOSE OF REVIEW

To summarize recent evidence and current trends in the use of haematopoietic stem cell transplantation (HSCT) for autoimmune diseases.

RECENT FINDINGS

Updates of published trials and data from the registries indicate a long-lasting, immunosuppression-free condition in about 50% of the patients who underwent an HSCT for a severe, progressive autoimmune disease. For all diseases, autologous HSCT is largely preferred for safety reasons, whereas allogeneic HSCT is to be considered only for carefully selected cases. Transplant-related mortality (TRM) has decreased in the past 5 years, due to both better selection of patients and the use of less intensive conditioning regimens. The most employed conditioning regimens in Europe are BCNU (carmustine), etoposide, ARA-C (cytosine arabinoside), M (melphalan) (BEAM)/anti-thymocyte globulin in multiple sclerosis and high-dose cyclophosphamide/anti-thymocyte globulin for all other diseases, with a trend for more intense regimens in North America. Multiple sclerosis and systemic sclerosis are currently the most frequent diagnoses. Prospective comparative trials are currently ongoing both in Europe and North America.

SUMMARY

Recent reports confirm the evidence that HSCT is able to induce a high rate of sustained remissions in most severe autoimmune diseases, unresponsive to conventional treatments. Valuable information is expected by the finalization of the ongoing prospective, comparative trials.

Novel therapeutic strategies for multiple sclerosis--a multifaceted adversary

Therapeutic strategies for multiple sclerosis have radically changed in the past 15 years. Five regulatory-approved immunomodulatory agents are reasonably effective in the treatment of relapsing-remitting multiple sclerosis, and appear to delay the time to progression to disabling stages. Inhibiting disease progression remains the central challenge for the development of improved therapies. As understanding of the immunopathogenesis of multiple sclerosis has advanced, a number of novel potential therapeutics have been identified, and are discussed here. It has also become apparent that traditional views of multiple sclerosis simply as a CD4+ T-cell-mediated disease of the central nervous system are incomplete. The pathogenic role of other immune components such as the innate immune system, regulatory T cells, T helper 17 cells and B cells is reaching centre stage, opening up exciting avenues and novel potential targets to affect the natural course of multiple sclerosis.

Autologous haematopoietic stem-cell transplantation in multiple sclerosis

Intense immunosuppression followed by autologous haematopoietic stem-cell transplantation has been assessed over the past few years as a possible new therapeutic strategy in severe forms of multiple sclerosis. Pioneering studies began in 1995, and since then, more than 400 patients worldwide have been treated with this procedure. Small uncontrolled studies show that about 60-70% of treated cases do not progress in the follow-up period of at least 3 years. Transplant-related mortality, which was 5-6% in the first reported series, has reduced in the past 5 years to 1-2%. Relapses dramatically decrease and inflammatory MRI activity is almost completely suppressed. Autologous haematopoietic stem-cell transplantation is associated with qualitative immunological changes in the blood, suggesting that, beyond its immunosuppressive potential, it could also have some beneficial effect for the resetting of the immune system. Patients with severe, rapidly worsening multiple sclerosis who are unresponsive to approved therapies could be candidates for this treatment, but its clinical efficacy has still to be shown in large, prospective, controlled studies.

Prolongation of cardiac allograft survival by syngeneic hematopoietic stem/progenitor cell transplantation in mice

INTRODUCTION

Organ transplantation is a rapidly developing field, being the only effective treatment for end-stage organ disease. However, the associated immunosuppressant therapy has numerous direct and indirect adverse effects. Hematopoietic stem cell transplantation (HSCT), via immune reconstitution, offers an alternative method of treatment. In this study, we determined the cardiac allograft survival in mice treated with syngeneic HSCT or hematopoietic progenitor cell transplantation (HPCT).

METHODS

BALB/c and C57BL/6 mice were randomly divided into three groups. Mice in Group A (n=7) were untreated while those in Group B (n=8) and C (n=7) were treated with HPCT and HSCT, respectively. Cervical heterotopic cardiac transplantation models were established in all groups and cardiac grafts were observed throughout. Regulatory T (Treg) cell expression in peripheral blood was analyzed by flow cytometry. We recorded the cardiac allograft survival time and constructed Kaplan-Meier survival curves.

RESULTS

The number of Treg cells in Group B was significantly higher than that in Group C (P<0.05). The survival time of mice from each group differed significantly according to Kaplan-Meier/log-rank analysis (P<0.01). A total of 62.5% of the grafts in Group B showed long-term survival (>100 days); all the mice in Group A died within 9 days, compared with 59 days in Group C.

CONCLUSION

We conclude that syngeneic HSCT and HPCT can prolong cardiac allograft survival in mice. These two methods could be promising ways to induce immune tolerance in future organ transplantation.

Adult stem cell treatment of scleroderma

PURPOSE OF REVIEW

Provides an update of hematopoietic stem cell transplantation for systemic sclerosis from phase I/II studies and prospective randomized phase III trials, and introduces the concept of mesenchymal stem cells as potential therapy for autoimmune disease.

RECENT FINDINGS

Around 170 transplanted systemic sclerosis patients are registered in Europe. Most received autologous, peripheral blood derived hematopoietic stem cell transplantation. Treatment-related mortality has fallen to 2.5% in the controlled trials compared with 12.5% in the first report in 2002. Over one-third of patients have experienced sustained remission. Two prospective randomized phase III studies are active: the Autologous Stem cell Transplantation International Scleroderma (ASTIS) trial in Europe and the Scleroderma Cyclophosphamide Or Transplant (SCOT) trial in the USA. Both have similar selection criteria, endpoint and control arms, but the SCOT trial uses radiation and less cyclophosphamide. So far, no unexpected toxicity has occurred. Reports produced in the past 12 months show reduction of skin collagen and reversal of microvascular remodelling, years after transplant. Bone marrow-derived mesenchymal stem cells from systemic sclerosis patients show in-vitro immunomodulatory properties equal to healthy controls.

SUMMARY

Hematopoietic stem cell transplantation is currently being tested in prospective randomized controlled trials and appears to 'reset' autoimmunity in systemic sclerosis. Mesenchymal stem cells may have an immunomodulatory role in autoimmune disease.

Autologous stem cell transplantation for severe autoimmune diseases: a 10-year experience

The first autologous hematopoietic stem cell transplantation in Europe for a patient with severe refractory systemic lupus erythematosus (SLE) was performed in Genoa in 1996. Since then, 32 patients with a wide spectrum of autoimmune diseases (ADs) received autologous transplants, 22 of them with multiple sclerosis (MS). There were no fatal adverse events. All patients had complete or very good partial remissions, but relapses were frequent, especially in SLE, though never as aggressive as pretransplant. The mechanism of action of this intervention remains not completely understood, as briefly discussed here.

[Haematopoietic stem cell transplantation in the treatment of autoimmune diseases]

PURPOSE

During the past ten years, more than 1000 patients suffering from severe autoimmune disease have received an autologous haematopoietic stem cell transplant. These new therapeutic have been used in systemic sclerosis (scleroderma), multiple sclerosis, rheumatoid arthritis, juvenile idiopathic arthritis and systemic lupus erythematosus.

CURRENT KNOWLEDGE AND KEY POINTS

Autologous haematopoietic stem cell transplantation has become a curative option for condition with very poor prognosis as severe systemic sclerosis, lupus erythematosus or other systemic diseases. This review summarizes the current experience in the phase I and II clinical trials in Europe and North America. We describe the main results and the limits of stem cell transplantation in systemic diseases.

FUTURE PROSPECTS AND PROJECTS

Autologous haematopoietic stem cell transplant in the treatment of autoimmune disease has evolved from a experimental concept to a clinically feasible and powerful therapy for selected patients with severe disease.

Resetting the adaptive immune system after autologous stem cell transplantation: lessons from responses to vaccines

Autologous stem cell transplantation (ASCT) to treat autoimmune diseases (AID) is thought to reset immunological memory directed against autoantigens. This hypothesis can only be studied indirectly because the exact nature of the pathogenetic autoantigens is unknown in most AID. Therefore, 19 children with juvenile idiopathic arthritis (JIA) or systemic lupus erythematodes (SLE) and 10 adults with multiple sclerosis (MS) were vaccinated with the T-cell-dependent neoantigen rabies and the recall antigen tetanus toxoid after, respectively before, bone marrow harvest. Both vaccinations were repeated after ASCT. All except two of the responders mounted a primary antibody response to rabies after revaccination, and 44% of the responders mounted a primary antibody response to tetanus boost after ASCT. These data show that immunological memory to a neoantigen is lost in most patients with AID after immunoablative pretreatment; however, memory to a recall antigen boosted before bone marrow harvest is only lost in part of the patients. Disease progression was arrested in all patients with JIA/SLE except one, but only in a minority of MS patients. Clinical outcome on a per case basis was not associated with the profile of the immune response toward the vaccination antigens after ASCT.

Autologous Haematopoietic Stem Cell Transplantation for the Treatment of Multiple Sclerosis

Introduction: Autologous haematopoietic stem cell transplantation (auto-HSCT) has been performed for severe multiple sclerosis (MS) refractory to standard therapy with increasing frequency worldwide. However, experience in Asia employing this modality in MS has been limited. In this review, we explored the pathophysiology of autoimmunity and the underlying rationale for auto-HSCT in treating autoimmune diseases including MS, as well as existing published pre-clinical and clinical data. We aimed thereby to better understand the utility of treating MS with auto-HSCT and the feasibility of this procedure in Singapore. Methods: A Medline search was performed with the terms “haematopoietic stem cell transplantation”, “multiple sclerosis” and “autoimmune diseases” from 1996 to 2005. Both original papers and review articles were considered. Main Findings: The majority of publications were from Europe or the United States and most clinical series from single centres had relatively small numbers of patients. Worldwide, the number of patients reported has been less than 300 since 1997. Existing data support the feasibility and promise of this procedure and ongoing Phase III trials may serve to confirm this initial experience. Conclusion: Pre-clinical and early clinical data support the rationale for immunoablative therapy for autoimmune disorders. Auto-HSCT for severe MS is a feasible procedure and can be safely performed in centres with experience managing HSCT patients. Key words: Autoimmunity, Induction of tolerance, Progressive multiple sclerosis

Catastrophic relapse of Evans syndrome five years after allogeneic BMT notwithstanding full donor chimerism. Terminal hemolytic-uremic syndrome

A patient with severe Evans syndrome received an allo-BMT from his HLA-identical sister on November, 2000. Full marrow and blood donor chimerism were achieved only after 5 donor lymphocyte infusions (DLI), and coincided with complete clinical remission and disappearence of auto-antibodies. Five years later, hemolytic anemia recurred with rapid increase of serum bilirubin to over 50 mg%: he responded to combined therapy, but died on day +17 from admission of an acute hemolytic uremic syndrome (HUS). All circulating blood cells, including erythrocytes, were 100% donor. Ex vivo cultured and expanded T and B cells from the peripheral blood were also 100% donor. The supernatants from B cell cultures, containing either IgM or IgG, did not react with a panel of erythrocytes. Thus in this typical autoimmune disease with a predominant B cell pathogenesis the donor immune system resulted "innocent of autoimmunity". The persistence of long-lived recipient autoreactive plasma-cell lines in survival niches, still producing autoantibodies, may be hypothesized for this and similar cases. The postulated graft-versus-autoimmunity (GVA) effect was apparently not sufficient to eradicate autoimmunity in this patient.

Bone marrow-derived stem cells in neurological diseases: stones or masons?

In spite of the commonly held belief that ‘the brain does not regenerate’, it is now accepted that postnatal neurogenesis does occur. Thus, one wonders whether cellular-replacement therapy might be used to heal the brain in diseases caused by neuronal cell loss. The existence of neural stem cells has been demonstrated by many scientists and is now generally accepted. The exact role of these cells, how their numbers are regulated and how they participate in CNS and spinal cord regeneration in postnatal life are still not well known. There are many reviews summarizing work on these cells; consequently, I will focus instead on other cells that may participate in postnatal neurogenesis: bone marrow-derived stem cells. The possibility that bone marrow-derived stem cells populate the CNS and differentiate into various neural elements is certainly not universally accepted.

Cell therapy for autoimmune diseases

Cell therapy, pioneered for the treatment of malignancies in the form of bone marrow transplantation, has subsequently been tested and successfully employed in autoimmune diseases. Autologous haemopoietic stem cell transplantation (HSCT) has become a curative option for conditions with very poor prognosis such as severe forms of scleroderma, multiple sclerosis, and lupus, in which targeted therapies have little or no effect. The refinement of the conditioning regimens has virtually eliminated transplant-related mortality, thus making HSCT a relatively safe choice. Although HSCT remains a nonspecific approach, the knowledge gained in this field has led to the identification of new avenues. In fact, it has become evident that the therapeutic efficacy of HSCT cannot merely be the consequence of a high-dose immuno-suppression, but rather the result of a resetting of the abnormal immune regulation underlying autoimmune conditions. The identification of professional and nonprofessional immunosuppressive cells and their biological properties is generating a huge interest for their clinical exploitation. Regulatory T cells, found abnormal in several autoimmune diseases, have been proposed as central to achieve long-term remissions. Mesenchymal stem cells of bone marrow origin have more recently been shown not only to be able to differentiate into multiple tissues, but also to exert a potent antiproliferative effect that results in the inhibition of immune responses and prolonged survival of haemopoietic stem cells. All of these potential resources clearly need to be investigated at the preclinical level but support a great deal of enthusiasm for cell therapy of autoimmune diseases.

Regulatory T cells control autoimmunity following syngeneic bone marrow transplantation

Sublethally irradiated, immunodeficient, C57BL/6 RAG-2 gene-deleted recipient mice reconstituted with T cell-depleted bone marrow (BM) grafts frequently developed diarrhea, lost weight and showed signs of autoimmunity, dying between 4 and 7 weeks after reconstitution. Mice died despite evidence of efficient donor-derived hemato-lymphoid reconstitution, and disease was associated with the presence of IgG anti-nuclear antibodies. Autoimmunity was initiated by T cells, but could be prevented by transfer of naturally arising regulatory T cells. In contrast, lethally irradiated, BM-reconstituted immunocompetent, C57BL/6 mice survived without signs of autoimmunity. Survival of immunocompetent mice was shown to be due to the presence of residual, extra-thymically located, radio-resistant, functional regulatory T cells. The importance of regulatory T cells was further shown by the reduced survival of immunocompetent BM recipients whose CD25+ T cells had been depleted prior to bone marrow transplantation. The implications of these results in the context of syngeneic graft-versus-host disease following BM transplantation are discussed.

Autologous hematopoietic stem cell transplantation for autoimmune diseases

Ten years have passed since the first published consensus statement on the use of hematopoietic stem cell transplantation (HSCT) in the treatment of severe autoimmune disease (AD) appeared. During that time, around 700 patients suffering from severe AD have undergone HSCT in the frame of phase I/II clinical trials from over 20 countries including the US. The majority have received an autologous HSCT using one of a limited number of regimens, consistent with the original consensus statement. Long-term drug-free remissions, remission then relapse, no response and treatment-related mortality (TRM) were seen in all the subgroups of AD. An overall TRM of 7% was observed, with marked variation between ADs, i.e. 11% in systemic lupus erythematosus (SLE) and only 1 patient in rheumatoid arthritis (RA). Phase III prospective, comparative randomized trials are running or being planned in multiple sclerosis (MS), systemic sclerosis (SSc), SLE and RA. Basic science programs are also being undertaken to study the immunological mechanisms underlying the clinical events observed.

Autologous hematopoietic stem cell transplantation for autoimmune diseases

Experimental data and early phase I/II studies suggest that high-dose chemotherapy followed by autologous hematopoietic stem cell transplantation (HSCT) can arrest progression of severe autoimmune diseases. We have evaluated the toxicity and disease response in 473 patients with severe autoimmune disease treated with autologous HSCT between 1995 and 2003, from 110 centers participating in the European Group for Blood and Marrow Transplantation (EBMT) autoimmune disease working party database. Survival, transplant-related mortality, treatment response and disease progression were assessed. In all, 420 patients (89%; 86+/-4% at 3 years, median follow-up 20 months) were alive, 53 (11%) had died from transplant-related mortality (N=31; 7+/-3% at 3 years) or disease progression (N=22; 9+/-4% at 3 years). Of 370 patients, 299 evaluable for response (81%) showed a treatment response, which was sustained in 213 (71% of responders). Response was associated with disease (P<0.001), was better in patients who received cyclophosphamide during mobilization (relative risk (RR)3.28 (1.57-6.83)) and was worse with increasing age (>40 years, RR0.29 (0.11-0.82)). Disease progression was associated with disease (P<0.001) and conditioning intensity (high intensity, RR1; intermediate intensity, RR1.81 (0.96-3.42)); low intensity, RR2.34 (1.074-5.11)). These data from the collective EBMT experience support the hypothesis that autologous HSCT can alter disease progression in severe autoimmune disease.

Haematopoietic stem cell transplantation in the treatment of severe autoimmune disease: results from phase I/II studies, prospective randomized trials and future directions

Around 700 patients have received an autologous haematopoietic stem cell transplant (HSCT) as treatment for a severe autoimmune disease (AD). The majority of these have been within the context of phase I/II clinical trials and following international guidelines proposed 7 years ago. In general, a positive benefit/risk ratio has led to phase III prospective randomized controlled trials in multiple sclerosis (MS), systemic sclerosis (SSc) and rheumatoid arthritis (RA) in Europe. In the US, similar trials are being planned for SSc, MS and systemic lupus erythematosus (SLE). Transplant related mortality (TRM) has fallen in all disease subgroups since the inception due to more appropriate patient selection, and so far a clear advantage of the more intense myeloablative regimens in terms of remission induction and relapse rate has not emerged. Although each AD has a different profile, over a third of patients have sustained a durable remission, often with no further need for immunosuppressive drugs. In those who relapsed, many responded to agents which pre transplant had been ineffective. The study of immune reconstitution and gene expression pre and post HSCT is being undertaken to further understand the mechanism of autoimmunity.

Human lymphoid and myeloid cell development in NOD/LtSz-scid IL2R gamma null mice engrafted with mobilized human hemopoietic stem cells

Ethical considerations constrain the in vivo study of human hemopoietic stem cells (HSC). To overcome this limitation, small animal models of human HSC engraftment have been used. We report the development and characterization of a new genetic stock of IL-2R common gamma-chain deficient NOD/LtSz-scid (NOD-scid IL2Rgamma(null)) mice and document their ability to support human mobilized blood HSC engraftment and multilineage differentiation. NOD-scid IL2Rgamma(null) mice are deficient in mature lymphocytes and NK cells, survive beyond 16 mo of age, and even after sublethal irradiation resist lymphoma development. Engraftment of NOD-scid IL2Rgamma(null) mice with human HSC generate 6-fold higher percentages of human CD45(+) cells in host bone marrow than with similarly treated NOD-scid mice. These human cells include B cells, NK cells, myeloid cells, plasmacytoid dendritic cells, and HSC. Spleens from engrafted NOD-scid IL2Rgamma(null) mice contain human Ig(+) B cells and lower numbers of human CD3(+) T cells. Coadministration of human Fc-IL7 fusion protein results in high percentages of human CD4(+)CD8(+) thymocytes as well human CD4(+)CD8(-) and CD4(-)CD8(+) peripheral blood and splenic T cells. De novo human T cell development in NOD-scid IL2Rgamma(null) mice was validated by 1) high levels of TCR excision circles, 2) complex TCRbeta repertoire diversity, and 3) proliferative responses to PHA and streptococcal superantigen, streptococcal pyrogenic exotoxin. Thus, NOD-scid IL2Rgamma(null) mice engrafted with human mobilized blood stem cells provide a new in vivo long-lived model of robust multilineage human HSC engraftment.