Reconstitution of the immune system and clinical correlates after stem cell transplantation for systemic sclerosis.

Systemic sclerosis (SSc) is a chronic autoimmune disease that includes fibrosis, diffuse vasculopathy, inflammation, and autoimmunity. Autologous hematopoietic stem cell transplantation (auto-HSCT) is considered for patients with severe and progressive SSc. In recent decades, knowledge about patient management and clinical outcomes after auto-HSCT has significantly improved. Mechanistic studies have contributed to increasing the comprehension of how profound and long-lasting are the modifications to the immune system induced by transplantation. This review revisits the immune monitoring studies after auto-HSCT for SSc patients and how they relate to clinical outcomes. This understanding is essential to further improve clinical applications of auto-HSCT and enhance patient outcomes.

Autologous hematopoietic stem cell transplantation modifies specific aspects of systemic sclerosis-related microvasculopathy.

Objective: Autologous hematopoietic stem cell transplantation (AHSCT) is a therapeutic option for patients with severe and progressive systemic sclerosis (SSc). Here, we aimed to investigate how AHSCT affects the vasculopathy of SSc patients. Methods: Twenty-seven SSc patients were retrospectively assessed, before and after AHSCT, for vessel morphology (nailfold capillaroscopy), skin expression of endothelial markers and serum levels of markers of inflammation, angiogenesis and endothelial activation. Skin biopsies were analyzed by immunohistochemistry (IHC) for expression of CD31, VE-cadherin, E-selectin, angiopoietin-1 (Ang1), angiopoietin-2 (Ang2), Tie-2, vascular endothelial growth factor A (VEGFA), vascular endothelial growth factor receptor 2 (VEGFR2), and endothelin-1 before and 12 months post-AHSCT. Serum samples from SSc patients were assessed before and up to 36 months after AHSCT for IL-6, von Willebrand factor (vWF), CXC Motif Chemokine Ligand 8 (CXCL8), Endothelin-1, epidermal growth factor (EGF), VEGFA, Pentraxin-3, Intercellular Adhesion Molecule 1 (ICAM-1), E-selectin, P-selectin, Thrombomodulin and IL-18 levels, and compared to healthy control samples. Results: On nailfold capillaroscopy, the number of capillaries increased at 1 year, while giant capillaries decreased at 6 months and 1 year after AHSCT. In the skin biopsies, expression of E-selectin notably decreased and Ang1 increased after AHSCT. At baseline, all vascular markers evaluated in the serum were significantly higher in SSc patients when compared to healthy controls, except for ICAM-1. When compared at different time points after AHSCT, Thrombomodulin, Pentraxin-3, vWF, and IL-18 levels remained generally stable at high levels until 36 months after AHSCT. Conclusion: Our results suggest that AHSCT contributes to improvements of the vessel morphology and dermal microvasculopathy, but does not normalize elevated levels of serum vascular markers in SSc patients. Additional vascular therapeutic approaches might contribute to more effectively treat the endothelial injury.

Autologous hematopoietic stem cell transplantation promotes connective tissue remodeling in systemic sclerosis patients.

BACKGROUND: Autologous hematopoietic stem cell transplantation (AHSCT) treats patients with severe and progressive systemic sclerosis (SSc). However, basic mechanisms associated with the therapeutic efficacy of the procedure are not entirely understood. We aimed to evaluate how AHSCT affects skin fibrosis in SSc patients. METHODS: Clinical data, serum, and skin samples from 39 SSc patients who underwent AHSCT were retrospectively evaluated. Skin biopsies were analyzed by immunohistochemistry with anti-MMP-1, -MMP-2, -MMP-3, -MMP-9, -TIMP-1, -α-SMA, -TGF-ß, and -NF-κB p65 antibodies, and stained with hematoxylin and eosin and picrosirius red to assess skin thickness and collagen density, respectively. Serum samples were evaluated by Multiplex Assay for COL1A1, COL4A1, FGF-1, MMP-1, MMP-3, MMP-12, MMP-13, PDGF-AA, PDGF-BB, S100A9, and TIMP-1 levels and compared to healthy controls. RESULTS: After AHSCT, SSc patients showed clinical improvement in skin involvement, assessed by modified Rodnan's skin score (mRSS). Histologically, collagen density and skin thickness decreased after AHSCT. Immunohistochemical analyses showed increased expression of MMP-2, MMP-3, MMP-9, and TIMP-1 after AHSCT, whereas expression of NF-κB p65 decreased. At baseline, serum levels of COL4A1 and S100A9 were higher than in healthy controls. Serum levels of S100A9 normalized after AHCST in SSc patients compared to controls. Serum levels of PDGF-AA, PDGF-BB, TIMP-1, and MMP-1 decreased, while COL1A1 increased after AHSCT in SSc patients. No changes were detected in MMP-3, MMP-12, MMP-13, and FGF-1 serum levels after AHSCT. CONCLUSIONS: Our results suggest that the therapeutic effects of AHSCT on skin fibrosis are related to changes in molecules associated with connective tissue maintenance and inflammation in SSc.

Autologous haematopoietic stem cell transplantation restores the suppressive capacity of regulatory B cells in systemic sclerosis patients.

OBJECTIVES: The rationale of autologous haematopoietic stem cell transplantation (AHSCT) for autoimmune diseases is that high-dose immunosuppression eradicates autoreactive T and B cells and the infused autologous haematopoietic stem cells promote reconstitution of a naïve and self-tolerant immune system. The aim of this study was to evaluate the reconstitution of different B cell subsets, both quantitatively and functionally, in SSc patients treated with AHSCT. METHODS: Peripheral blood was harvested from 22 SSc patients before transplantation and at 30, 60, 120, 180 and 360 days post-AHSCT. Immunophenotyping of B cell subsets, B cell cytokine production, signalling pathways and suppressive capacity of regulatory B cells (Bregs) were assessed by flow cytometry. RESULTS: Naïve B cell frequencies increased from 60 to 360 days post-AHSCT compared with pre-transplantation. Conversely, memory B cell frequencies decreased during the same period. Plasma cell frequencies transiently decreased at 60 days post-AHSCT. IL-10-producing Bregs CD19+CD24hiCD38hi and CD19+CD24hiCD27+ frequencies increased at 180 days. Moreover, the phosphorylation of extracellular signal-regulated kinase 1/2 and p38 mitogen-activated protein kinase increased in B cells reconstituted post-AHSCT. Notably, CD19+CD24hiCD38hi Bregs recovered their ability to suppress production of Th1 cytokines by CD4+ T cells at 360 days post-AHSCT. Finally, IL-6 and TGF-ß1-producing B cells decreased following AHSCT. CONCLUSION: Taken together, these results suggest improvements in immunoregulatory and anti-fibrotic mechanisms after AHSCT for SSc, which may contribute to re-establishment of self-tolerance and clinical remission.

Priming approaches to improve the efficacy of mesenchymal stromal cell-based therapies.

Multipotent mesenchymal stromal cells (MSC) have been widely explored for cell-based therapy of immune-mediated, inflammatory, and degenerative diseases, due to their immunosuppressive, immunomodulatory, and regenerative potentials. Preclinical studies and clinical trials have demonstrated promising therapeutic results although these have been somewhat limited. Aspects such as low in vivo MSC survival in inhospitable disease microenvironments, requirements for ex vivo cell overexpansion prior to infusions, intrinsic differences between MSC and different sources and donors, variability of culturing protocols, and potency assays to evaluate MSC products have been described as limitations in the field. In recent years, priming approaches to empower MSC have been investigated, thereby generating cellular products with improved potential for different clinical applications. Herein, we review the current priming approaches that aim to increase MSC therapeutic efficacy. Priming with cytokines and growth factors, hypoxia, pharmacological drugs, biomaterials, and different culture conditions, as well as other diverse molecules, are revised from current and future perspectives.

Correction to: Priming approaches to improve the efficacy of mesenchymal stromal cell-based therapies.

The original article [1] contained an error in the presentation of the first author's name, Nádia de Cássia Noronha. This has now been corrected.

A Toll-like receptor 2 genetic variant modulates occurrence of bacterial infections in patients with sickle cell disease.

Despite adequate immunization and penicillin prophylaxis, bacterial infections remain a leading cause of morbidity and mortality in patients with sickle cell disease (SCD). Besides hyposplenism, inflammatory and genetic factors might modulate their susceptibility to bacterial infections. We performed a candidate gene association of single nucleotide polymorphisms (SNPs) located in Toll-like receptor (TLR) genes, encoding prominent molecules for innate immune responses, with the occurrence of bacterial infections in patients with SCD. A cohort followed in centres in Brazil, France and Senegal (n = 430) was divided in two groups: patients who presented at least one episode of bacterial infection (n = 235) and patients who never had bacterial infections (n = 195). There were no differences in gender or age distribution among the groups. The frequency of the TLR2 rs4696480 TA genotype was significantly lower in the infected group (50% vs. 67%, odds ratio [OR] = 0·50, 95% confidence interval [CI] 0·34-0·75, P < 0·001), and the TT genotype was significantly higher in the infected group (15% vs. 5%, OR = 3·18, 95% CI 1·53-6·61, P < 0·001). Previous reports demonstrated higher secretion of inflammatory factors in cells from AA individuals, lower occurrence and severity of immune diseases in T carriers. The rs4696480 TA genotype might stand between deleterious effects of over inflammatory response (AA genotype) and inefficient responses (TT genotype) to infectious agents in SCD settings.

New Horizons in the Treatment of Type 1 Diabetes: More Intense Immunosuppression and Beta Cell Replacement.

Since the discovery of autoimmunity as the main pathophysiologic process involved in type 1 diabetes, many attempts have tried to delay or stop beta cell destruction. Most research protocols in humans have investigated the effects of therapeutic agents targeting specific steps of the autoimmune response. In spite of safety and some degree of beta cell preservation, the clinical impact of such approaches was similar to placebo. Recently, research groups have analyzed the effects of a more intense and wider immunologic approach in newly diagnosed type 1 diabetic individuals with the "immunologic reset," i.e., high-dose immunosuppression followed by autologous hematopoietic stem cell transplantation. This more aggressive approach has enabled the majority of patients to experience periods of insulin independence in parallel with relevant increments in C-peptide levels during mixed meal tolerance test. However, on long-term follow-up, almost all patients resumed exogenous insulin use, with subsequent decrease in C-peptide levels. This has been at least in part explained by persistence of islet-specific T-cell auto-reactivity. Here, we discuss future steps to induce immune tolerance in individuals with type 1 diabetes, with emphasis on risks and possible benefits of a more intense transplant immunosuppressive regimen, as well as strategies of beta cell replacement not requiring immunomodulation.

Homeostatic proliferation leads to telomere attrition and increased PD-1 expression after autologous hematopoietic SCT for systemic sclerosis.

In the months that follow autologous hematopoietic stem cell transplantation (AHSCT), lymphopenia drives homeostatic proliferation, leading to oligoclonal expansion of residual cells. Here we evaluated how replicative senescent and exhausted cells associated with clinical outcomes of 25 systemic sclerosis (SSc) patients who underwent AHSCT. Patients were clinically monitored for skin (modified Rodnan's skin score, mRSS) and internal organ involvement and had blood samples collected before and semiannually, until 3 years post-AHSCT, for quantification of telomere length, CD8+CD28- and PD-1+ cells, and serum cytokines. Patients were retrospectively classified as responders (n = 19) and non-responders (n = 6), according to clinical outcomes. At 6 months post-AHSCT, mRSS decreased (P < 0.001) and the pulmonary function stabilized, when compared with pre-transplant measures. In parallel, inflammatory cytokine (IL-6 and IL-1ß) levels and telomere lengths decreased, whereas PD-1 expression on T-cells and the number of CD8+CD28- cells expressing CD57 and FoxP3 increased. After AHSCT, responder patients presented higher PD-1 expression on T- (P < 0.05) and B- (P < 0.01) cells, and lower TGF-ß, IL-6, G-CSF (P < 0.01), and IL-1ß, IL-17A, MIP-1α, and IL-12 (P < 0.05) levels than non-responders. Homeostatic proliferation after AHSCT results in transient telomere attrition and increased numbers of senescent and exhausted cells. High PD-1 expression is associated with better clinical outcomes after AHSCT.

Immune rebound associates with a favorable clinical response to autologous HSCT in systemic sclerosis patients.

To evaluate the immunological mechanisms associated with clinical outcomes after autologous hematopoietic stem cell transplantation (AHSCT), focusing on regulatory T- (Treg) and B- (Breg) cell immune reconstitution, 31 systemic sclerosis (SSc) patients underwent simultaneous clinical and immunological evaluations over 36-month posttransplantation follow-up. Patients were retrospectively grouped into responders (n = 25) and nonresponders (n = 6), according to clinical response after AHSCT. Thymic function and B-cell neogenesis were respectively assessed by quantification of DNA excision circles generated during T- and B-cell receptor rearrangements. At the 1-year post-AHSCT evaluation of the total set of transplanted SSc patients, thymic rebound led to renewal of the immune system, with higher T-cell receptor (TCR) diversity, positive correlation between recent thymic emigrant and Treg counts, and higher expression of CTLA-4 and GITR on Tregs, when compared with pretransplant levels. In parallel, increased bone marrow output of newly generated naive B-cells, starting at 6 months after AHSCT, renovated the B-cell populations in peripheral blood. At 6 and 12 months after AHSCT, Bregs increased and produced higher interleukin-10 levels than before transplant. When the nonresponder patients were evaluated separately, Treg and Breg counts did not increase after AHSCT, and high TCR repertoire overlap between pre- and posttransplant periods indicated maintenance of underlying disease mechanisms. These data suggest that clinical improvement of SSc patients is related to increased counts of newly generated Tregs and Bregs after AHSCT as a result of coordinated thymic and bone marrow rebound.

Immunological Balance Is Associated with Clinical Outcome after Autologous Hematopoietic Stem Cell Transplantation in Type 1 Diabetes.

Autologous hematopoietic stem cell transplantation (AHSCT) increases C-peptide levels and induces insulin independence in patients with type 1 diabetes. This study aimed to investigate how clinical outcomes may associate with the immunological status, especially concerning the balance between immunoregulation and autoreactivity. Twenty-one type 1 diabetes patients were monitored after AHSCT and assessed every 6 months for duration of insulin independence, C-peptide levels, frequencies of islet-specific autoreactive CD8+ T cells (CTL), regulatory lymphocyte subsets, thymic function, and T-cell repertoire diversity. In median follow-up of 78 (range 15-106) months, all patients became insulin-independent, resuming insulin after median of 43 (range 6-100) months. Patients were retrospectively divided into short- or prolonged-remission groups, according to duration of insulin independence. For the entire follow-up, CD3+CD4+ T-cell numbers remained lower than baseline in both groups, whereas CD3+CD8+ T-cell levels did not change, resulting in a CD4/CD8 ratio inversion. Memory CTL comprehended most of T cells detected on long-term follow-up of patients after AHSCT. B cells reconstituted to baseline levels at 2-3 months post-AHSCT in both patient groups. In the prolonged-remission-group, baseline islet-specific T-cell autoreactivity persisted after transplantation, but regulatory T cell counts increased. Patients with lower frequencies of autoreactive islet-specific T cells remained insulin-free longer and presented greater C-peptide levels than those with lower frequencies of these cells. Therefore, immune monitoring identified a subgroup of patients with superior clinical outcome of AHSCT. Our study shows that improved immunoregulation may balance autoreactivity endorsing better metabolic outcomes in patients with lower frequencies of islet-specific T cells. Development of new strategies of AHSCT is necessary to increase frequency and function of T and B regulatory cells and decrease efficiently autoreactive islet-specific T and B memory cells in type 1 diabetes patients undergoing transplantation.

Transcriptional profiling reveals intrinsic mRNA alterations in multipotent mesenchymal stromal cells isolated from bone marrow of newly-diagnosed type 1 diabetes patients.

BACKGROUND: Bone marrow multipotent mesenchymal stromal cells (MSCs) are a diverse subset of precursors that contribute to the homeostasis of the hematopoietic niche. MSCs can be isolated and expanded in vitro and have unique immunomodulatory and regenerative properties that make them attractive for the treatment of autoimmune diseases, including type 1 diabetes (T1D). Whether autologous or allogeneic MSCs are more suitable for therapeutic purposes has not yet been established. While autologous MSCs may present abnormal function, allogeneic cells may be recognized and rejected by the host immune system. Thus, studies that investigate biological characteristics of MSCs isolated from T1D patients are essential to guide future clinical applications. METHODS: Bone marrow-derived MSCs from recently diagnosed type 1 diabetes patients (T1D-MSCs) were compared with those from healthy individuals (C-MSCs) for morphological and immunophenotypic characteristics and for differentiation potential. Bioinformatics approaches allowed us to match absolute and differential gene expression of several adhesion molecules, immune mediators, growth factors, and their receptors involved with hematopoietic support and immunomodulatory properties of MSCs. Finally, the differentially expressed genes were collated for functional pathway enrichment analysis. RESULTS: T1D-MSCs and C-MSCs were similar for morphology, immunophenotype, and differentiation potential. Our absolute gene expression results supported previous literature reports, while also detecting new potential molecules related to bone marrow-derived MSC functions. T1D-MSCs showed intrinsic abnormalities in mRNA expression, including the immunomodulatory molecules VCAM-1, CXCL12, HGF, and CCL2. Pathway analyses revealed activation of sympathetic nervous system and JAK STAT signaling in T1D-MSCs. CONCLUSIONS: Collectively, our results indicate that MSCs isolated from T1D patients present intrinsic transcriptional alterations that may affect their therapeutic potential. However, the implications of these abnormalities in T1D development as well as in the therapeutic efficacy of autologous MSCs require further investigation.

Immunological correlates of favorable long-term clinical outcome in multiple sclerosis patients after autologous hematopoietic stem cell transplantation.

High dose immunosuppression followed by autologous hematopoietic stem cell transplantation (AHSCT) induces prolonged clinical remission in multiple sclerosis (MS) patients. However, how patient immune profiles are associated with clinical outcomes has not yet been completely elucidated. In this study, 37 MS patients were assessed for neurological outcomes, thymic function and long-term immune reconstitution after AHSCT. Patients were followed for a mean (SD) of 68.5 (13.9) months post-transplantation and were retrospectively clustered into progression- and non-progression groups, based on Expanded Disease Status Scale (EDSS) outcomes at last visit. After AHSCT, both patient groups presented increased regulatory T-cell subset counts, early expansion of central- and effector-memory CD8(+)T-cells and late thymic reactivation. However, the non-progression group presented early expansion of PD-1(+)CD8(+)T-cells and of PD-1-expressing CD19(+) B-cells. Here, we suggest that along with increased numbers of regulatory T-cell subsets, PD-1 inhibitory signaling is one possible immunoregulatory mechanism by which AHSCT restores immune tolerance in MS patients.

Mast cells control insulitis and increase Treg cells to confer protection against STZ-induced type 1 diabetes in mice.

Quantitative alterations in mast cell numbers in pancreatic lymph nodes (PLNs) have been reported to be associated with type 1 diabetes (T1D) progression, but their potential role during T1D remains unclear. In this study, we evaluated the role of mast cells in T1D induced by multiple low-dose streptozotocin (MLD-STZ) treatments, using two strains of mast cell-deficient mice (W/W(v) or Wsh/Wsh) and the adoptive transfer of mast cells. Mast cell deficient mice developed severe insulitis and accelerated hyperglycemia, with 100% of mice becoming diabetic compared to their littermates. In parallel, these diabetic mice had decreased numbers of T regulatory (Treg) cells in the PLNs. Additionally, mast cell deficiency caused a significant reduction in IL-10, TGF-ß, and IL-6 expression in the pancreatic tissue. Interestingly, IL-6-deficient mice are more susceptible to T1D associated with reduced Treg-cell numbers in the PLNs, but mast cell transfer from wild-type mice induced protection to T1D in these mice. Finally, mast cell adoptive transfer prior to MLD-STZ administration conferred resistance to T1D, promoted increased Treg cells, and decreased IL-17-producing T cells in the PLNs. Taken together, our results indicate that mast cells are implicated in resistance to STZ-induced T1D via an immunological tolerance mechanism mediated by Treg cells.

A Methodology for the Development of RESTful Semantic Web Services for Gene Expression Analysis.

Gene expression studies are generally performed through multi-step analysis processes, which require the integrated use of a number of analysis tools. In order to facilitate tool/data integration, an increasing number of analysis tools have been developed as or adapted to semantic web services. In recent years, some approaches have been defined for the development and semantic annotation of web services created from legacy software tools, but these approaches still present many limitations. In addition, to the best of our knowledge, no suitable approach has been defined for the functional genomics domain. Therefore, this paper aims at defining an integrated methodology for the implementation of RESTful semantic web services created from gene expression analysis tools and the semantic annotation of such services. We have applied our methodology to the development of a number of services to support the analysis of different types of gene expression data, including microarray and RNASeq. All developed services are publicly available in the Gene Expression Analysis Services (GEAS) Repository at http://dcm.ffclrp.usp.br/lssb/geas. Additionally, we have used a number of the developed services to create different integrated analysis scenarios to reproduce parts of two gene expression studies documented in the literature. The first study involves the analysis of one-color microarray data obtained from multiple sclerosis patients and healthy donors. The second study comprises the analysis of RNA-Seq data obtained from melanoma cells to investigate the role of the remodeller BRG1 in the proliferation and morphology of these cells. Our methodology provides concrete guidelines and technical details in order to facilitate the systematic development of semantic web services. Moreover, it encourages the development and reuse of these services for the creation of semantically integrated solutions for gene expression analysis.

Autologous haematopoietic stem cell transplantation reduces abnormalities in the expression of immune genes in multiple sclerosis.

Autologous haematopoietic stem-cell transplantation (AHSCT) has been experimented as a treatment in patients affected by severe forms of multiple sclerosis (MS) who failed to respond to standard immunotherapy. The rationale of AHSCT is to 'reboot' the immune system and reconstitute a new adaptive immunity. The aim of our study was to identify, through a robust and unbiased transcriptomic analysis, any changes of gene expression in T-cells potentially underlying the treatment effect in patients who underwent non-myeloablative AHSCT for treatment of MS. We evaluated by microarray DNA-chip technology the gene expression of peripheral CD4+ and CD8+ T-cell subsets sorted from patients with MS patients before AHSCT, at 6 months, 1 year and 2 years after AHSCT and from healthy control subjects. Hierarchical clustering analysis revealed that reconstituted CD8+ T-cells of MS patients at 2 years post-transplantation, aggregated together with healthy controls, suggesting a normalization of gene expression in CD8+ cells post-therapy. When we compared the gene expression in MS patients before and after therapy, we detected a large number of differentially expressed genes (DEG) in both CD8+ and CD4+ T-cell subsets at all time points after transplantation. We catalogued the biological function of DEG and we selected 27 genes known to be involved in immune function for accurate quantification of gene expression by real-time PCR. The analysis confirmed and extended with quantitative data, a number of significant changes in both the CD4+ and CD8+ T-cells subsets from MS post-transplant. Notably, CD8+ T-cells revealed more extensive changes in the expression of genes involved in effector immune responses.

Bone marrow mesenchymal stromal cells isolated from multiple sclerosis patients have distinct gene expression profile and decreased suppressive function compared with healthy counterparts.

Multiple sclerosis (MS) is a chronic inflammatory autoimmune disease of the central nervous system, due to an immune reaction against myelin proteins. Multipotent mesenchymal stromal cells (MSCs) present immunosuppressive effects and have been used for the treatment of autoimmune diseases. In our study, gene expression profile and in vitro immunomodulatory function tests were used to compare bone marrow-derived MSCs obtained from MS patients, at pre- and postautologous hematopoietic stem cell transplantation (AHSCT) with those from healthy donors. Patient MSCs comparatively exhibited i) senescence in culture; ii) similar osteogenic and adipogenic differentiation potential; iii) decreased expression of CD105, CD73, CD44, and HLA-A/B/C molecules; iv) distinct transcription at pre-AHSCT compared with control MSCs, yielding 618 differentially expressed genes, including the downregulation of TGFB1 and HGF genes and modulation of the FGF and HGF signaling pathways; v) reduced antiproliferative effects when pre-AHSCT MSCs were cocultured with allogeneic T-lymphocytes; vi) decreased secretion of IL-10 and TGF-ß in supernatants of both cocultures (pre- and post-AHSCT MSCs); and vii) similar percentages of regulatory cells recovered after MSC cocultures. The transcriptional profile of patient MSCs isolated 6 months posttransplantation was closer to pre-AHSCT samples than from healthy MSCs. Considering that patient MSCs exhibited phenotypic changes, distinct transcriptional profile and functional defects implicated in MSC immunomodulatory and immunosuppressive activity, we suggest that further MS clinical studies should be conducted using allogeneic bone marrow MSCs derived from healthy donors. We also demonstrated that treatment of MS patients with AHSCT does not reverse the transcriptional and functional alterations observed in patient MSCs.

Stem cell therapy for diabetes mellitus.

In this review, we present (1) a brief discussion of hematopoietic stem cell transplantation (HSCT) for severe and refractory autoimmune diseases (AIDs) from its beginning in 1996 through recently initiated prospective randomized clinical trials; (2) an update (up to July 2009) of clinical and laboratory outcomes of 23 patients with newly diagnosed type 1 diabetes mellitus (T1DM), who underwent autologous HSCT at the Bone Marrow Transplantation Unit of the Ribeirão Preto Medical School, University of São Paulo, Brazil; (3) a discussion of possible mechanisms of action of HSCT in AIDs, including preliminary laboratory data obtained from our patients; and (4) a discussion of future perspectives of stem cell therapy for T1DM and type 2 DM, including the use of stem cell sources other than adult bone marrow and the combination of cell therapy with regenerative compounds.