Abnormal immunity and stem/progenitor cells in acquired aplastic anemia

Traditional Chinese medicines and natural products targeting immune cells in the treatment of metabolic-related fatty liver disease

MAFLD stands for metabolic-related fatty liver disease, which is a prevalent liver disease affecting one-third of adults worldwide, and is strongly associated with obesity, hyperlipidemia, and type 2 diabetes. It encompasses a broad spectrum of conditions ranging from simple liver fat accumulation to advanced stages like chronic inflammation, tissue damage, fibrosis, cirrhosis, and even hepatocellular carcinoma. With limited approved drugs for MAFLD, identifying promising drug targets and developing effective treatment strategies is essential. The liver plays a critical role in regulating human immunity, and enriching innate and adaptive immune cells in the liver can significantly improve the pathological state of MAFLD. In the modern era of drug discovery, there is increasing evidence that traditional Chinese medicine prescriptions, natural products and herb components can effectively treat MAFLD. Our study aims to review the current evidence supporting the potential benefits of such treatments, specifically targeting immune cells that are responsible for the pathogenesis of MAFLD. By providing new insights into the development of traditional drugs for the treatment of MAFLD, our findings may pave the way for more effective and targeted therapeutic approaches.

Levamisole Suppresses CD4+ T-Cell Proliferation and Antigen-Presenting Cell Activation in Aplastic Anemia by Regulating the JAK/STAT and TLR Signaling Pathways

Aplastic anemia (AA) is a life-threatening disease primarily caused by a metabolic disorder and an altered immune response in the bone marrow (BM) microenvironment, where cytotoxic immune cells attack resident cells and lead to hematopoietic failure. We previously reported an efficient strategy by applying cyclosporin (CSA) combined with levamisole (CSA+LMS-based regimen) in the treatment of AA, but the immunoregulatory mechanism of LMS was still unclear. Here, the therapeutic effects of LMS were examined in vivo using the BM failure murine model. Meanwhile, the proportion and related function of T cells were measured by flow cytometry in vivo and in vitro. The involved signaling pathways were screened by RNA-seq and virtual binding analysis, which were further verified by interference experiments using the specific antagonists on the targeting cells by RT-PCR in vitro. In this study, the CSA+LMS-based regimen showed a superior immune-suppressive response and higher recession rate than standard CSA therapy in the clinical retrospective study. LMS improved pancytopenia and extended the survival in an immune-mediated BM failure murine model by suppressing effector T cells and promoting regulatory T-cell expansion, which were also confirmed by in vitro experiments. By screening of binding targets, we found that JAK1/2 and TLR7 showed the highest docking score as LMS targeting molecules. In terms of the underlying molecular mechanisms, LMS could inhibit JAK/STAT and TLR7 signaling activity and downstream involved molecules. In summary, LMS treatment could inhibit T-cell activation and downregulate related molecules by the JAK/STAT and TLR signaling pathways, supporting the valuable clinical utility of LMS in the treatment of AA.

Structural and Temporal Dynamics of Mesenchymal Stem Cells in Liver Diseases From 2001 to 2021: A Bibliometric Analysis

Background

Mesenchymal stem cells (MSCs) have important research value and broad application prospects in liver diseases. This study aims to comprehensively review the cooperation and influence of countries, institutions, authors, and journals in the field of MSCs in liver diseases from the perspective of bibliometrics, evaluate the clustering evolution of knowledge structure, and discover hot trends and emerging topics.

Methods

The articles and reviews related to MSCs in liver diseases were retrieved from the Web of Science Core Collection using Topic Search. A bibliometric study was performed using CiteSpace and VOSviewer.

Results

A total of 3404 articles and reviews were included over the period 2001-2021. The number of articles regarding MSCs in liver diseases showed an increasing trend. These publications mainly come from 3251 institutions in 113 countries led by China and the USA. Li L published the most papers among the publications, while Pittenger MF had the most co-citations. Analysis of the most productive journals shows that most are specialized in medical research, experimental medicine and cell biology, and cell & tissue engineering. The macroscopical sketch and micro-representation of the whole knowledge field are realized through co-citation analysis. Liver scaffold, MSC therapy, extracellular vesicle, and others are current and developing areas of the study. The keywords "machine perfusion", "liver transplantation", and "microRNAs" also may be the focus of new trends and future research.

Conclusions

In this study, bibliometrics and visual methods were used to review the research of MSCs in liver diseases comprehensively. This paper will help scholars better understand the dynamic evolution of the application of MSCs in liver diseases and point out the direction for future research.

Immunosuppression characterized by increased Treg cell and IL-10 levels in benzene-induced hematopoietic toxicity mouse model

Benzene is a typical hematopoietic toxic substance, that can cause serious blood and circulatory system diseases such as aplastic anemia, myelodysplastic syndrome and acute myeloid leukemia, but the immunological mechanism by which this occurs is not clear. T helper cells play a key role in regulating the immune balance in the body. In this study, benzene-induced hematopoietic toxicity BALB/c mice model was established, and changes in immune organs and T helper cell subsets (Th1, Th2, Th17 and Treg cells) were explored. At 28 days after subcutaneous injection of 150 mg/kg benzene, mice showed pancytopenia and obvious pathological damage to the bone marrow, spleen, and thymus. Flow cytometry revealed that the number of CD4⁺CD25⁺Foxp3⁺ Treg cells in the spleen increased significantly. The level of IL-10 in the spleen, serum, and bone marrow increased, while the levels of IL-17 in the spleen and serum decreased. Furthermore, the levels of CD4 and CD8 proteins in the spleen decreased. Immunofluorescence results showed that levels of Foxp3, a specific transcription factor that induced the differentiation of Treg cells, increased after exposure to benzene. Our results demonstrate that immunosuppression occurred in the benzene-induced hematopoietic toxicity model mice, and Treg cells and secreted IL-10 may play a key role in the process.

Immunologic effects on the haematopoietic stem cell in marrow failure

Acquired bone marrow failure (BMF) syndromes comprise a diverse group of diseases with variable clinical manifestations but overlapping features of immune activation, resulting in haematopoietic stem and progenitor cells (HSPC) damage and destruction. This review focuses on clinical presentation, pathophysiology, and treatment of four BMF: acquired aplastic anaemia, large granular lymphocytic leukaemia, paroxysmal nocturnal haemoglobinuria, and hypoplastic myelodysplastic syndrome. Autoantigens are speculated to be the inciting event that result in immune activation in all of these diseases, but specific pathogenic antigens have not been identified. Oligoclonal cytotoxic T cell expansion and an active role of proinflammatory cytokines, primarily interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α), are two main contributors to HSPC growth inhibition and apoptosis in BMF. Emerging evidence also suggests involvement of the innate immune system.

Outcomes of haploidentical bone marrow transplantation in patients with severe aplastic anemia-II that progressed from non-severe acquired aplastic anemia

Severe aplastic anemia II (SAA-II) progresses from non-severe aplastic anemia (NSAA). The unavailability of efficacious treatment has prompted the need for haploidentical bone marrow transplantation (haplo-BMT) in patients lacking a human leukocyte antigen (HLA)-matched donor. This study aimed to investigate the efficacy of haplo-BMT for patients with SAA-II. Twenty-two patients were included and followed up, and FLU/BU/CY/ATG was used as conditioning regimen. Among these patients, 21 were successfully engrafted, 19 of whom survived after haplo-BMT. Four patients experienced grade II-IV aGvHD, including two with grade III-IV aGvHD. Six patients experienced chronic GvHD, among whom four were mild and two were moderate. Twelve patients experienced infections during BMT. One was diagnosed with post-transplant lymphoproliferative disorder and one with probable EBV disease, and both recovered after rituximab infusion. Haplo-BMT achieved 3-year overall survival and disease-free survival rate of 86.4% ± 0.73% after a median follow-up of 42 months, indicating its effectiveness as a salvage therapy. These promising outcomes may support haplo-BMT as an alternative treatment strategy for patients with SAA-II lacking HLA-matched donors.

Prolonged hematologic toxicity following treatment with chimeric antigen receptor T cells in patients with hematologic malignancies

Chimeric antigen receptor T-cell therapy (CAR T) is a novel intervention for relapsed/refractory diffuse large B-cell lymphoma (R/R DLBCL) and other hematologic malignancies. However, it is associated with prolonged hematologic toxicity (PHT) that is unpredictable and can significantly impair patients' quality of life. Reported here is a single-center experience with PHT in adult patients with R/R DLBCL who received commercial CAR T-cell therapy between March 1, 2018 and May 30, 2020. Prolonged hematologic toxicity was defined as ≥ grade 3 neutropenia or thrombocytopenia at day +30 after CAR T-cell therapy. Of the 31 patients identified, 18 patients (58%) developed PHT. Patients with PHT had a shorter 1-year overall survival (OS) than patients without PHT (36% vs. 81%, P < .05). There were no differences in the median time to ANC recovery for those with PHT compared to patients without PHT (16 days vs. 15 days). Several risk factors were identified to be associated with PHT including CRS (P = .002), receipt of tocilizumab (P = .002) or steroids (P = .033), peak ferritin >5000 ng/ml (P = .048), peak C-reactive protein (CRP) > 100 mg/L (P = .007), and ferritin greater than the upper limit of normal at day +30. Seven patients with PHT underwent a bone marrow biopsy after CAR T-cell therapy; all showed complete aplasia or were hypocellular with cellularity ranging from <5% to 10%. These findings identify PHT as a significant toxicity associated with CAR T-cell therapy and highlight the critical need for further investigations to describe PHT in larger cohorts and identify standards for management of this condition.

Effect of arsenic trioxide on the Tregs ratio and the levels of IFN-γ, IL-4, IL-17 and TGF-β1 in the peripheral blood of severe aplastic anemia patients

Previous studies have suggested that the anticancer agent, arsenic trioxide (ATO), could attenuate T cell mediated immunity by not only inhibiting the proliferative response of T cells but by also increasing the frequency of regulatory T cells (Tregs). Furthermore, ATO represents a reasonable salvage treatment in some patients with refractory severe aplastic anemia (SAA). The current study aimed to evaluate the function of ATO on the Tregs percentage and cytokines changes in the peripheral blood mononuclear cells (PBMCs) of SAA patients.PBMCs were collected from 20 newly diagnosed SAA patients in Henan Cancer Hospital and treated with different concentrations of ATO (0, 1, 2.5, and 5 μmol/L). Then we investigated the efficacy of ATO on Tregs ratio and the levels of interferon (IFN)-γ, interleukin (IL)-4, IL-17 and transforming growth factor (TGF)-β1 in the peripheral blood of SAA patients in vitro.The results showed that ATO significantly increased the proportion of Tregs (P < .001) at 2.5 and 5 μmol/L concentrations, and the proportion of Tregs was increased with increasing ATO concentration (r = 0.524). At 1 (P = .03), 2.5 (P < .001) and 5 μmol/L (P < .001), ATO significantly up-regulated the expression levels of Foxp3 mRNA, which was positively and linearly correlated with the increase of Tregs cell-frequency (r = 0.52, 95%CI, 0.37-0.67). In addition, ATO significantly reduced the levels of IFN-γ (at 1, 2.5 and 5 μmol/L, P < .001), IL-4 (at 2.5 μmol/L, P = .009; at 5 μmol/L, P < .001), and IL-17 (at 2.5, P = .016; at 5 μmol/L, P < .001). ATO significantly reduced the levels of TGF-β1 at 5 μmol/L (P = .03), but showed no significant effects at 1 and 2.5 μmol/L (P > .05).ATO could mediate the immune regulation, which might contribute to improve hematopoietic recovery in SAA patients.

Gadofullerene nanoparticles for robust treatment of aplastic anemia induced by chemotherapy drugs

Aplastic anemia (AA) is characterized as hypoplasia of bone marrow hematopoietic cells and hematopenia of peripheral blood cells. Though the supplement of exogenous erythropoietin (EPO) has been clinically approved for AA treatment, the side-effects hinder its further application. Here a robust treatment for AA induced by chemotherapy drugs is explored using gadofullerene nanoparticles (GFNPs).

Methods: The gadofullerene were modified with hydrogen peroxide under alkaline conditions to become the water-soluble nanoparticles (GFNPs). The physicochemical properties, in vitro chemical construction, stability, hydroxyl radical scavenging ability, in vitro cytotoxicity, antioxidant activity, in vivo treatment efficacy, therapeutic mechanism and biological distribution, metabolism, toxicity of GFNPs were examined.

Results: GFNPs with great stability and high-efficiency antioxidant activity could observably increase the number of red blood cells (RBC) in the peripheral blood of AA mice and relieve the abnormal pathological state of bone marrow. The erythropoiesis mainly includes hemopoietic stem cells (HSCs) differentiation, erythrocyte development in bone marrow and erythrocyte maturation in peripheral blood. The positive control-EPO promotes erythropoiesis by regulating HSCs differentiation and erythrocyte development in bone marrow. Different from the anti-AA mechanism of EPO, GFNPs have little impact on both the differentiation of HSCs and the myeloid erythrocyte development, but notably improve the erythrocyte maturation. Besides, GFNPs can notably decrease the excessive reactive oxygen species (ROS) and inhibit apoptosis of hemocytes in blood. In addition, GFNPs are mostly excreted from the living body and cause no serious toxicity.

Conclusion: Our work provides an insight into the advanced nanoparticles to powerfully treat AA through ameliorating the erythrocyte maturation during erythropoiesis.

Pathogenesis of aplastic anemia

Aplastic anemia (AA) is a rare and life-threatening bone marrow failure (BMF) that results in peripheral blood cytopenia and reduced bone marrow hematopoietic cell proliferation. The symptoms are similar to myelofibrosis, myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) making diagnosis of AA complicated. The pathogenesis of AA is complex and its mechanism needs to be deciphered on an individualized basis. This review summarizes several contributions made in trying to understand AA pathogenesis in recent years which may be helpful for the development of personalized therapies for AA.

PPAR Gamma-Regulated MicroRNA 199a-5p Underlies Bone Marrow Adiposity in Aplastic Anemia

Increased propensity of bone marrow-derived mesenchymal stem cells (BM-MSCs) toward adipogenic differentiation has been implicated in the fatty bone marrow and defective hematopoiesis of aplastic anemia (AA). However, the underlying molecular mechanism remains to be investigated. In this study, we found that microRNA 199a-5p (miR-199a-5p) exhibits significantly higher expression in AA BM-MSCs compared with the normal control and is demonstrated to facilitate adipogenic differentiation of BM-MSCs through lentivirus-mediated miR-199a overexpression. Mechanistic investigation reveals that miR-199a-5p could be regulated by PPAR gamma (PPARγ) in a transcription-independent manner and regulates adipogenic differentiation by targeting the expression of transforming growth factor beta induced (TGFBI), which is subsequently validated as a negative regulator of adipogenesis. Besides, the positive correlation between PPARγ and miR-199a-5p expression as well as the inverse relationship between miR-199a-5p and TGFBI expression in normal and AA BM-MSCs was observed. Altogether, our work demonstrates that PPARγ-regulated miR-199a-5p promotes adipogenesis of BM-MSCs by inhibiting TGFBI expression, which might be a novel mechanism underlying the bone marrow adiposity in AA, and provides promising therapeutic targets for AA treatment.

Contribution of autophagy-related gene 5 variants to acquired aplastic anemia in Han-Chinese population

Immune-mediated quantitative and qualitative defects of hematopoietic stem/progenitor cells (HSPCs) play a vital role in the pathophysiology of acquired aplastic anemia (AA). Autophagy is closely related to T cell pathophysiology and the destiny of HSPCs, in which autophagy-related gene 5 (ATG5) is indispensably involved. We hypothesized that genetic variants of ATG5 might contribute to AA. We studied six ATG5 polymorphisms in a Chinese cohort of 176 patients with AA to compare with 157 healthy controls. A markedly decreased risk of AA in the recessive models of rs510432 and rs803360 polymorphisms (adjusted odds ratio [OR], 95% confidence interval [CI] = 0.467 [0.236-0.924], P = 0.029 for ATG5 rs510432; adjusted OR [95% CI] = 0.499 [0.255-0.975], P = 0.042 for ATG5 rs803360) was observed. Furthermore, the decreased risk was even more pronounced among nonsevere AA compared with healthy controls under recessive models (adjusted OR [95% CI] = 0.356 [0.141-0.901], P = 0.029 for ATG5 rs510432; adjusted OR [95% CI] = 0.348 [0.138-0.878], P = 0.025 for ATG5 rs803360; adjusted OR [95% CI] = 0.352 [0.139-0.891], P = 0.027 for ATG5 rs473543). Above all, rs573775 can strongly predict the occurrence of newly onset hematological event in patients with AA. Our results indicate that genetic ATG5 variants contributed to AA, which may facilitate further clarifying the underlying mechanisms of AA and making a patient-tailored medical decision.

Altered expression of leptin and leptin receptor in the development of immune-mediated aplastic anemia in mice

The current study aimed to explore the levels of leptin (LEP) and LEP receptor (LEP-R) on the progression of aplastic anemia (AA) with bone marrow fat conversion. An AA model was developed by infusing C57BL/6 lymph node cells into BALB/c mice. At 0, 3, 6, 9, 12, 15 and 18 days after modeling, routine blood counts, bone marrow biopsy slides, lymphocyte subsets (CD4⁺ and CD8⁺ T cells) and cytokine levels [including interleukin (IL)-2, IL-4, IL-5 and interferon-γ] were assessed. LEP and LEP-R levels in peripheral blood serum, mesenchymal stem cells (MSCs) and bone marrow were also analyzed by enzyme-linked immunosorbent assay, polymerase chain reaction and immunohistochemistry. The relevance of LEP, LEP-R and other factors was analyzed by Pearson's correlation analysis. Peripheral pancytopenia (reduced count of white blood cells, red blood cells, hemoglobin and platelets), abnormal immune factor levels and histological changes in bone marrow sections were detected in the AA model mice, suggesting that these mice mimicked the pathological changes commonly observed in AA. In addition, following the establishment of AA, the LEP level was gradually increased and the LEP-R level was reduced in the mice over time (P<0.05). The expression of adipogenic genes, including CCAAT/enhancer-binding protein (C/EBP)α, C/EBPβ and peroxisome proliferator-activated receptor γ, was markedly increased, while the expression of the osteogenic gene runt-related transcription factor 2 was reduced compared with the levels in the control group (P<0.05). Taken together, damage to LEP-R may lead to dysregulation of LEP and the enhancement of MSCs to differentiate into adipocytes, resulting in excessive fat in bone marrow of AA patients.

Roles of regulatory T cells in the pathogenesis of pediatric aplastic anemia

The pathogenesis of aplastic anemia (AA) in children is not clear. This study was conducted to investigate the changes in the proportion and function of regulatory T cells (Tregs) in pediatric AA. The proportion of Tregs, mRNA levels of transcription factors, and concentrations of cytokines were measured by flow cytometry, reverse transcription-PCR, and enzyme-linked immunosorbent assay, respectively. Tregs were co-cultured with effector T cells (Teff) to evaluate the function of Tregs. The proportion of Tregs after immunosuppressive therapy (IST) in pediatric AA was monitored dynamically. Compared to the control, the proportions of Tregs in peripheral blood and bone marrow lymphocytes of the untreated AA group were lower (1.31% ± 0.73% vs. 3.16% ± 0.92%, 1.49% ± 0.81% vs. 3.06% ± 0.82%, respectively, p < 0.001). The mRNA levels of FOXP3 and STAT3 in the AA group were lower (p = 0.014; p < 0.001). However, the mRNA levels of T-BET did not significantly differ between groups. The concentration of interferon-γ and interleukin-17 in the AA group were higher (p = 0.004; p = 0.003), whereas the concentration of TGF-β decreased (p = 0.044). The immunosuppressive function of Tregs was impaired in the AA group. After IST, the proportion of Tregs was significantly lower than that in the control. The proportion of Tregs at the time of diagnosis in the nonresponsive group was lower than that in the responsive group, but the difference was not significant. Treg levels were significantly decreased and were functionally impaired at the time of diagnosis of pediatric AA. However, there was no significant change in Tregs at the resolution of AA.

Effect of nutritional supplement on bone marrow-derived mesenchymal stem cells from aplastic anaemia

Aplastic anaemia (AA) is characterised by pancytopenia resulting from a marked reduction in haemopoietic stem cells (HSC). The regulation of haemopoiesis depends on the interaction between HSC and various cells of the bone marrow (BM) microenvironment, including BM-derived mesenchymal stromal cells (BMSC). The purpose of this study was to analyse the biological effect of nutritional supplement (NS), a dietary supplement consisting of thirty-six compounds: amino acids, nucleotides, vitamins and micronutrients on the BMSC of AA rats. The AA rat model was established by irradiating X-ray (2·5 Gy) and intraperitoneal injections of cyclophosphamide (35 mg/kg; Sigma) and chloramphenicol (35 mg/kg; Sigma). Then AA rats were fed with NS in a dose-dependent manner (2266·95, 1511·3, 1057·91 mg/kg d) by intragastric administration. The effect of NS on the BMSC of AA rats was analysed. As compared with AA rats, NS treatment significantly improved these peripheral blood parameters and stimulated the proliferation of total femoral nucleated cells. NS treatment affected proliferative behaviour of BMSC and suppressed BMSC differentiation to adipocytes. Furthermore, NS treatment of AA rats accelerated osteogenic differentiation of BMSC and enhanced bone mineral density. Co-incubation of HSC with mesenchymal stromal cells and serum from AA rats subjected to high-dose NS markedly improved the yield of CD34+cells. Protein microarray analysis revealed that there were eleven differentially expressed proteins in the NS group compared with the AA rat group. The identified specific NS might be implicated in rehabilitation of BMSC in AA rats, suggesting their potential of nutritional support in AA treatment.

Pathogenesis of Acquired Aplastic Anemia and the Role of the Bone Marrow Microenvironment

Aplastic anemia (AA) is characterized by bone marrow (BM) hypocellularity, resulting in peripheral cytopenias. An antigen-driven and likely auto-immune dysregulated T-cell homeostasis results in hematopoietic stem cell injury, which ultimately leads to the pathogenesis of the acquired form of this disease. Auto-immune and inflammatory processes further influence the disease course as well as response rate to therapy, mainly consisting of intensive immunosuppressive therapy and allogeneic hematopoietic cell transplantation. Bone marrow hematopoietic stem and progenitor cells are strongly regulated by the crosstalk with the surrounding microenvironment and its components like mesenchymal stromal cells, also consistently altered in AA. Whether latter is a contributing cause or rather consequence of the disease remains an open question. Overall, niche disruption may contribute to disease progression, sustain pancytopenia and promote clonal evolution. Here we review the existing knowledge on BM microenvironmental changes in acquired AA and discuss their relevance for the pathogenesis and therapy.

Levamisole suppresses adipogenesis of aplastic anaemia-derived bone marrow mesenchymal stem cells through ZFP36L1-PPARGC1B axis

Aplastic anaemia (AA) is a life-threatening hematopoietic disorder characterized by hypoplasia and pancytopenia with increasing fat cells in the bone marrow (BM). The BM-derived mesenchymal stem cells (MSCs) from AA are more susceptible to be induced into adipogenic differentiation compared with that from control, which may be causatively associated with the fatty BM and defective hematopoiesis of AA. Here in this study, we first demonstrated that levamisole displayed a significant suppressive effect on the in vitro adipogenic differentiation of AA BM-MSCs. Mechanistic investigation revealed that levamisole could increase the expression of ZFP36L1 which was subsequently demonstrated to function as a negative regulator of adipogenic differentiation of AA BM-MSCs through lentivirus-mediated ZFP36L1 knock-down and overexpression assay. Peroxisome proliferator-activated receptor gamma coactivator 1 beta (PPARGC1B) whose 3'-untranslated region bears adenine-uridine-rich elements was verified as a direct downstream target of ZFP36L1, and knock-down of PPARGC1B impaired the adipogenesis of AA BM-MSCs. Collectively, our work demonstrated that ZFP36L1-mediated post-transcriptional control of PPARGC1B expression underlies the suppressive effect of levamisole on the adipogenic differentiation of AA BM-MSCs, which not only provides novel therapeutic targets for alleviating the BM fatty phenomenon of AA patients, but also lays the theoretical and experimental foundation for the clinical application of levamisole in AA therapy.

Saponins from Panax notoginseng leaves improve the symptoms of aplastic anemia and aberrant immunity in mice

Aplastic anemia (AA) is usually treated with immunosuppressive agents, but their efficacy and safety are not satisfactory. Panax notoginseng saponins (PNS) promote the proliferation of hematopoietic stem/progenitor cells. This study aimed to examine the effects of leaf PNS (LPNS) on hematopoiesis and T cells in mouse models of AA. The experiments were performed in normal mice and AA mice (controls, cyclosporine, and low, medium, and high doses of LPNS). Hematopoietic cells were counted using colony formation assays. The proportions of T cells were measured by flow cytometry. The ERK1/2, T-bet, GATA-3, FOXP3, and RORγ proteins were assessed by western blotting. Cytokines were measured using a cytometric bead array. AA mice showed impaired hematopoiesis, high activation of T cells, and decreased expression of T-bet, GATA-3, and FOXP3. LPNS attenuated the inflammation observed in AA mice, and significantly increased the number of hematopoietic progenitor cells. The proportions of Th2 and regulatory T cells and the protein levels of P-ERK1/2, GATA-3, and FOXP3 were increased in the AA + LPNS mice compared with the AA mice. In contrast, LPNS decreased the proportions of Th1 and Th17 cells and the protein expression of T-bet. LPNS and cyclosporine had similar effects, but of different amplitudes. These results suggest that LPNS have dual activities in AA: 1) promoting the proliferation of hematopoietic progenitor cells; and 2) modulating T cell immune functions, an activity similar to that of cyclosporine. Additional studies are necessary to confirm those results before clinical use.

Mesenchymal Stem Cell Benefits Observed in Bone Marrow Failure and Acquired Aplastic Anemia

Acquired aplastic anemia (AA) is a type of bone marrow failure (BMF) syndrome characterized by partial or total bone marrow (BM) destruction resulting in peripheral blood (PB) pancytopenia, which is the reduction in the number of red blood cells (RBC) and white blood cells (WBC), as well as platelets (PLT). The first-line treatment option of AA is given by hematopoietic stem cell (HSCs) transplant and/or immunosuppressive (IS) drug administration. Some patients did not respond to the treatment and remain pancytopenic following IS drugs. The studies are in progress to test the efficacy of adoptive cellular therapies as mesenchymal stem cells (MSCs), which confer low immunogenicity and are reliable allogeneic transplants in refractory severe aplastic anemia (SAA) cases. Moreover, bone marrow stromal cells (BMSC) constitute an essential component of the hematopoietic niche, responsible for stimulating and enhancing the proliferation of HSCs by secreting regulatory molecules and cytokines, providing stimulus to natural BM microenvironment for hematopoiesis. This review summarizes scientific evidences of the hematopoiesis improvements after MSC transplant, observed in acquired AA/BMF animal models as well as in patients with acquired AA. Additionally, we discuss the direct and indirect contribution of MSCs to the pathogenesis of acquired AA.

CD106 is a novel mediator of bone marrow mesenchymal stem cells via NF-κB in the bone marrow failure of acquired aplastic anemia

BACKGROUND

Acquired aplastic anemia (AA) is characterized by deficiency or dysfunction of the bone marrow (BM) microenvironment. However, little is known about the impairment of BM-derived mesenchymal stem cells (MSCs) in AA patients.

METHODS

We used Illumina HiSeqTM 2000 sequencing, quantitative real-time polymerase chain reaction (qRT-PCR), flow cytometry (FCM), and Western blotting to test the expression of CD106 gene (vascular cell adhesion molecule 1 (VCAM1)) and CD106 protein of BM-MSCs. Furthermore, we used hematoxylin and eosin (H&E) and histochemical staining analysis, immunofluorescence, and the formation of capillary-like structures to analyze capillary tube-like formation in vitro; we also used the Matrigel plug assay to test in vivo vasculogenesis, and an assay of colony forming units (CFUs) and colony-forming unit-megakaryocyte (CFU-MK) to detect the support function of MSCs in vitro. The in vivo engraftment of CD34⁺ cells and MSCs in NOD/SCID mice was tested by FACS and survival assay; the expression of NF-κB was tested by NanoPro analysis and immunofluorescence. NF-κB-regulated CD106 gene (VCAM1) was confirmed by tumor necrosis factor alpha (TNF-α)-stimulated and lipopolysaccharide (LPS)-stimulated MSCs, blockade assay, and immunofluorescence.

RESULTS

Here, we report that BM-MSCs from AA patients exhibited downregulation of the CD06 gene (VCAM1) and low expression of CD106 in vitro. Further analysis revealed that CD106⁺ MSCs from both AA patients and healthy controls had increased potential for in vitro capillary tube-like formation and in vivo vasculogenesis compared with CD106^- MSCs, and the results were similar when healthy MSCs were compared with AA MSCs. CD106⁺ MSCs from both AA patients and healthy controls more strongly supported in vitro growth and in vivo engraftment of CD34⁺ cells in NOD/SCID mice than CD106^- MSCs, and similar results were obtained when healthy MSCs and AA MSCs were compared. The expression of NF-κB was decreased in AA MSCs, and NF-κB regulated the CD106 gene (VCAM1) which supported hematopoiesis.

CONCLUSIONS

These results revealed the effect of CD106 and NF-κB in BM failure of AA.

Pro-inflammatory effects of the Th1 chemokine CXCL10 in acquired aplastic anaemia

CXCL10/IFN-γ-induced protein 10 (IP-10) and its corresponding receptor CXCR3 have long been considered to be involved in the pathophysiology of type 1 T (Th1) cell-orientated autoimmune diseases. However, the exact role of CXCL10 in the pathogenesis of aplastic anaemia (AA) has not been thoroughly studied. The aim of our study was to evaluate the plasma level of CXCL10 and its effects on CD4⁺ T cell differentiation in AA. In our study, we found that an elevated plasma level of CXCL10 was negatively correlated with platelet, absolute neutrophil and reticulocyte counts, while it was positively correlated with the proportion of lymphocytes in white blood cells in AA patients. To confirm the pro-inflammatory effects of CXCL10 in AA, we isolated CD4⁺ T cells and evaluated the function of CXCL10 in CD4⁺ T cell differentiation. In vitro stimulation experiments further revealed the pro-inflammatory role of CXCL10 in AA, partially by promoting the secretion of interferon (IFN)-γ and IL-17. In addition, CXCL10 significantly skewed CD4⁺ T cell differentiation to Th1 cells and T helper 17 (Th17) cells in AA patients, while it inhibited the differentiation of type 2 T (Th2) cells only in controls. The mRNA expression of transcription factors representative of T cell differentiation was detected by RT-PCR. Consistently, our results showed that after CXCL10 treatment, the expression of T-bet and RORγt was significantly enhanced, while the expression of GATA3 was inhibited. In conclusion, our results indicated that CXCL10, a pro-inflammatory chemokine, might be involved in the abnormal immune response in AA.

Polymorphisms of the TGF-β1 gene and the risk of acquired aplastic anemia in a Chinese population

Acquired aplastic anemia (AA) is a hematological disease characterized by failure of bone marrow hematopoiesis resulting in pancytopenia. While immune-mediated destruction of hematopoietic stem/progenitor cells (HSPCs) plays a central role in the pathophysiology of acquired AA, the transforming growth factor-β1 (TGF-β1) is crucial in adjusting the immune system. The aim of our study was to investigate the role of TGF-β1 gene polymorphisms rs1800469 and rs2317130 in susceptibility to acquired AA. Via the approach of SNaPshot, we genotyped rs1800469 and rs2317130 in 101 patients with acquired AA and 165 controls. It derived us to the conclusion that the genotype TT of rs1800469 (C/T) was significantly associated with decreased risk of acquired AA (adjusted OR = 0.39, 95% CI = 0.18-0.83, P = 0.014). Furthermore, this decreased risk was more pronounced among male patients (adjusted OR = 0.35, 95% CI = 0.13-0.95, P = 0.038) and SAA/vSAA (severe AA/very severe AA) patients (adjusted OR = 0.31, 95% CI = 0.12-0.77, P = 0.02) compared with controls in subgroup analysis. However, a significant increased risk was observed in the genotype distributions of rs2317130 for TT genotype (adjusted OR = 2.52, 95% CI = 1.03-6.19, P = 0.04) compared with the CC genotype among the SAA/vSAA patients and controls in the severity stratification analysis. Our results indicated that TGF-β1 gene polymorphisms might be involved in the munity of acquired AA in a Chinese population. This initial analysis provides valuable clues for further study of TGF-β1 pathway genes in acquired AA.

In patients with chronic aplastic anemia, bone marrow-derived MSCs regulate the Treg/Th17 balance by influencing the Notch/RBP-J/FOXP3/RORγt pathway

The standard treatment for aplastic anemia (AA) in young patients is a matched sibling hematopoietic stem cell transplant. Transfusion of a chronic AA patient with allogeneic bone marrow–derived mesenchymal stromal cells (BMMSCs) is currently being developed as a cell-based therapy, and the safety and efficacy of such transfusions are being continuously improved. Nevertheless, the mechanisms by which BMMSCs exert their therapeutic effects remain to be elucidated. In this study, mesenchymal stromal cells (MSCs) obtained from bone marrow donors were concentrated and intravenously injected into 15 chronic AA patients who had been refractory to prior immunosuppressive therapy. We showed that BMMSCs modulate the levels of Th1, Th2, Th17 and Treg cells, as well as their related cytokines in chronic AA patients. Furthermore, the percentages of Th1 and Th17 cells among the H-MSCs decreased significantly, while the percentage Treg cells increased. The Notch/RBP-J/FOXP3/RORγt pathway was involved in modulating the Treg/Th17 balance after MSCs were transfused in vitro. Additionally, the role played by transfused MSCs in regulating the Treg/Th17 balance via the Notch/RBP-J/FOXP3/RORγt pathway was further confirmed in an AA mouse model. In summary, in humans with chronic AA, BMMSCs regulate the Treg/Th17 balance by affecting the Notch/RBP-J/FOXP3/RORγt pathway.

Role of vitamin D receptor gene polymorphisms in aplastic anemia: a case-control study from China

INTRODUCTION

Vitamin D receptor (VDR) gene and its polymorphisms are highlighted as candidate components for susceptibility to various autoimmune diseases. The aim of this study was to investigate the role of VDR polymorphisms (rs2228570, rs1544410, rs7975232, and rs731236) in aplastic anemia (AA).

METHODS

In this case-control study, the genotyping of VDR rs1544410 (c.1024 + 283G>A), rs7975232 (c.1025-49G>T), and rs731236 (c.1056T>C) polymorphisms was conducted using polymerase chain reaction (PCR)-ligase detection reaction, while the genotyping of rs2228570 (c.2T>C) was detected by PCR-restriction fragment length polymorphism.

RESULTS

The frequencies of GG genotype and G allele of rs1544410 were significantly higher in patients with AA than in controls. Further analysis indicated that rs1544410 and rs7975232 polymorphisms were correlated with the risk to nonsevere AA, while rs2228570 was relevant to severe AA. Moreover, TT carriers of rs2228570 were closely associated with a poor response to treatment and a higher risk of myelodysplastic syndrome/acute leukemia transformation, while CT carriers more easily evolved to overt paroxysmal nocturnal hemoglobinuria.

CONCLUSIONS

VDR polymorphisms may contribute to susceptibility to AA and influence the severity and prognosis of AA in a Chinese population.

The association of cytokine genes polymorphisms and susceptibility to aplastic anemia in Egyptian patients

BACKGROUND AND OBJECTIVE

Aplastic anemia (AA) remains a rare disease, with very interesting pathophysiology that is being investigated for years now. The present study aimed to determine the association between cytokine gene polymorphisms (TGF-β1 -509 C/T, TNF-α -308 G/A, IFN-γ +874 A/T) and susceptibility to AA in Egyptian patients.

METHODS

The study included 80 participants subjected to determination of gene polymorphisms on genomic DNA using polymerase chain reaction-restriction fragment length polymorphism assay.

RESULTS

It was found that IFN-γ +874 A/T gene polymorphism is associated with three-fold increased risk of development of AA (odds ratio (OR) 3.116, P = 0.019), while TNF-α -308 G/A gene polymorphism is associated with decreased risk (OR 0.318, P = 0.026). TGF-β1 -509 C/T gene polymorphism showed comparable risk between patients and controls (P = 0.263).

CONCLUSION

IFN-γ +874 A/T gene polymorphism is associated with the etiology of AA in Egyptian patients.

Inflammation as a Driver of Clonal Evolution in Myeloproliferative Neoplasm

Our understanding of inflammation's role in the pathogenesis of myeloproliferative neoplasm (MPN) is evolving. The impact of chronic inflammation, a characteristic feature of MPN, likely goes far beyond its role as a driver of constitutional symptoms. An inflammatory response to the neoplastic clone may be responsible for some pathologic aspects of MPN. Moreover, JAK2V617F mutated hematopoietic stem and progenitor cells are resistant to inflammation, and this gives the neoplastic clone a selective advantage allowing for its clonal expansion. Because inflammation plays a central role in MPN inflammation is a logical therapeutic target in MPN.

Anti-inflammatory effects of interleukin-35 in acquired aplastic anemia

Interleukin (IL)-35 is a novel regulatory cytokine primarily produced by regulatory T cells. Accumulating evidence has established that IL-35 plays an important role in the regulation of immune homeostasis, but little is known regarding the function of IL-35 in acquired aplastic anemia (AA). The aim of the present study was to investigate the expression of IL-35 and its effects on T cell response in AA. Our study demonstrated that significantly decreased plasma levels of IL-35 in AA were closely correlated with disease severity. In vitro stimulation experiment further confirmed the anti-inflammatory effects of IL-35, including suppressing the proliferation of CD4(+) and CD8(+) effector T cells, inhibiting the secretion of interferon-γ, tumor necrosis factor-α and IL-17 and promoting the production of transforming growth factor-β by peripheral blood mononuclear cells from patients with AA. Furthermore, we established that IL-35 inhibited the differentiation of type 1 T cells and T helper 17 cells but promoted the differentiation of type 2 T cells. Accordingly, the expression of T-bet and RORγt was inhibited while the expression of GATA3 was induced after IL-35 treatment. In summary, our findings suggested that decreased IL-35 might contribute to the loss of immune-tolerance and be critically involved in the pathogenesis of AA.

TNF-α-induced programmed cell death in the pathogenesis of acquired aplastic anemia

The mechanism of acquired aplastic anemia (AA), a bone marrow hematopoiesis failure disease, has not been fully understood. TNF-α is a pleiotropic cytokine involved in cell proliferation, differentiation and death, and inflammation through binding to specific receptors on cell membranes. Aberrant secretion of TNF-α contributes to a number of human diseases, including tumor development and inflammation. TNF-α is also an important negative regulator of hematopoiesis. Over-expression of TNF-α not only directly inhibits the proliferation and differentiation of hematopoietic cells, but also initiates the intracellular death pathway to induce hematopoietic cell death, leading to bone marrow hematopoiesis failure. In this review, we summarize the mechanisms underlying extrinsic apoptosis and necroptosis of hematopoietic cells induced by TNF-α, and discuss the role of TNF-α-induced programmed cell death in the pathogenesis of acquired AA.

Antithymocyte globulin combined with cyclosporine A down-regulates T helper 1 cells by modulating T cell immune response cDNA 7 in aplastic anemia

Antithymocyte globulin (ATG) combined with cyclosporine A (CsA) has been widely used as a standard regimen in the treatment of aplastic anemia (AA), especially in severe aplastic anemia (SAA). Abnormally activated T cells might be the immune pathogenesis of AA. T cell immune response cDNA 7 (TIRC7) has been demonstrated its essential role in T cell activation; however, little is known about the role of TIRC7 in AA. In this study, we documented that TIRC7 levels in CsA group were higher than that in ATG + CsA (AC) group only in the follow-up phase (P < 0.05; P < 0.05); nevertheless, TIRC7 levels in SAA group were elevated than non severe aplastic anemia group not only in the treatment phase (P < 0.05; P < 0.05) but also in the follow-up phase (P < 0.05; P < 0.01). The trend of changes of T helper (Th) 1, Th17 and Th22 levels before and after treatment was similar to the changes of TIRC7 levels in either AC group or CsA group. Thus, TIRC7 might be involved in the pathogenesis of AA and AC might down-regulate Th1 cells by modulating the expression of TIRC7 in AA.

The complex pathophysiology of acquired aplastic anaemia

Immune-mediated destruction of haematopoietic stem/progenitor cells (HSPCs) plays a central role in the pathophysiology of acquired aplastic anaemia (aAA). Dysregulated CD8(+) cytotoxic T cells, CD4(+) T cells including T helper type 1 (Th1), Th2, regulatory T cells and Th17 cells, natural killer (NK) cells and NK T cells, along with the abnormal production of cytokines including interferon (IFN)-γ, tumour necrosis factor (TNF)-α and transforming growth factor (TGF)-β, induce apoptosis of HSPCs, constituting a consistent and defining feature of severe aAA. Alterations in the polymorphisms of TGF-β, IFN-γ and TNF-α genes, as well as certain human leucocyte antigen (HLA) alleles, may account for the propensity to immune-mediated killing of HSPCs and/or ineffective haematopoiesis. Although the inciting autoantigens remain elusive, autoantibodies are often detected in the serum. In addition, recent studies provide genetic and molecular evidence that intrinsic and/or secondary deficits in HSPCs and bone marrow mesenchymal stem cells may underlie the development of bone marrow failure.

Involvement of interleukin-21 in the pathophysiology of aplastic anemia

OBJECTIVE

Recently enhanced T-helper type 17 (Th17) immune responses and deficient CD4(+) CD25(hi) FoxP3(+) regulatory T cells (Tregs) have been reported in acquired aplastic anemia (AA). Interleukin-21 (IL-21), a CD4(+) T-cell-derived proinflammatory cytokine, modulates the balance between Th17 cells and Tregs. However, its role in AA remains unclear.

METHODS

IL-21 gene expression was examined by quantitative real-time PCR. Cytokines in plasma and cell culture supernatants were detected by ELISA. Cytokines-producing T cells and Tregs were evaluated by flow cytometry.

RESULTS

IL-21 mRNA levels in circulating CD4(+) T cells and IL-21 levels in blood plasma were markedly increased in patients with newly diagnosed AA. Moreover, elevated IL-21-producing CD4(+) T cells were accompanied by Th17 cells accumulation and Tregs decrease, and correlated with AA activity. In vitro, IL-21 not only inhibited the expression of FoxP3, but also induced the expression of IL-17 in CD4(+) T cells of AA patients. More importantly, we found that T cells within the bone marrow (BM) of AA patients were in a heightened activation state, which may be related to IL-21.

CONCLUSION

Our data suggested a critical role of IL-21 in breaking immune homeostasis in AA by promoting Th17 cells, activating BM T cells and suppressing Tregs.

TRAF1/C5 rs10818488 polymorphism is not a genetic risk factor for acquired aplastic anemia in a Chinese population

The tumor necrosis factor receptor-associated factor 1/complement C5 (TRAF1/C5) genes have been suggested as two candidate genes for conferring susceptibility to autoimmunity and inflammation. The aim of the present study was to investigate the association of single nucleotide polymorphisms (SNP) of TRAF1/C5 genes with the risk for aplastic anemia (AA). In this case-control study, the genotyping of TRAF1/C5 rs10818488 polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The frequencies of AA, AG and GG genotypes, and A and G alleles were 21.9%, 52.4%, 25.7%, 48.1% and 51.9%, respectively, in AA patients. There was no significant differences in terms of genotype and allele distributions between AA patients and healthy controls (P=0.687 and 0.955, respectively). Similar results were found between the two groups when stratified by the disease severity including very severe AA (vSAA), SAA and non-SAA (NSAA). Our results indicated that TRAF1/C5 rs10818488 polymorphism might not contribute to susceptibility to AA in a Chinese population.

IFN-γ causes aplastic anemia by altering hematopoietic stem/progenitor cell composition and disrupting lineage differentiation

Aplastic anemia (AA) is characterized by hypocellular marrow and peripheral pancytopenia. Because interferon gamma (IFN-γ) can be detected in peripheral blood mononuclear cells of AA patients, it has been hypothesized that autoreactive T lymphocytes may be involved in destroying the hematopoietic stem cells. We have observed AA-like symptoms in our IFN-γ adenylate-uridylate-rich element (ARE)-deleted (del) mice, which constitutively express a low level of IFN-γ under normal physiologic conditions. Because no T-cell autoimmunity was observed, we hypothesized that IFN-γ may be directly involved in the pathophysiology of AA. In these mice, we did not detect infiltration of T cells in bone marrow (BM), and the existing T cells seemed to be hyporesponsive. We observed inhibition in myeloid progenitor differentiation despite an increase in serum levels of cytokines involved in hematopoietic differentiation and maturation. Furthermore, there was a disruption in erythropoiesis and B-cell differentiation. The same phenomena were also observed in wild-type recipients of IFN-γ ARE-del BM. The data suggest that AA occurs when IFN-γ inhibits the generation of myeloid progenitors and prevents lineage differentiation, as opposed to infiltration of activated T cells. These results may be useful in improving treatment as well as maintaining a disease-free status.

Arsenic trioxide and microRNA-204 display contrary effects on regulating adipogenic and osteogenic differentiation of mesenchymal stem cells in aplastic anemia

Our previous studies have demonstrated that arsenic trioxide (ATO) had the clinical efficacy in treating patients with aplastic anemia (AA). However, the mechanisms remain to be elucidated. The important components of the bone marrow hematopoietic microenvironment, bone marrow mesenchymal stem cells (BMSCs), are often altered in AA patients. In this study, it was found that AA BMSCs were prone to be induced into adipocytes rather than osteoblasts. ATO treatment can at least partially restore the differentiation imbalance of AA BMSCs. We further identified miR-204 as a key regulator in AA BMSC differentiation. Luciferase reporter assay showed that miR-204 could directly bind to the 3'-untranslated region of Runx2 mRNA, a key transcription factor regulating osteogenesis. Moreover, adipogenic differentiation was promoted and osteogenic differentiation was inhibited in miR-204 over-expressed cells, whereas osteogenesis was enhanced and adipocyte formation was inhibited in cells that lost miR-204 function, which suggested its endogenous function. Together we showed that ATO could inhibit adipogenic differentiation, but promote osteogenic differentiation in AA BMSCs, providing a possible explanation for ATO clinical efficacy in AA patients. MiR-204 plays a key role in regulating BMSCs differentiation, and down-regulating miR-204 expression might be a novel strategy to treat AA.

New therapeutic approaches for protecting hematopoietic stem cells in aplastic anemia

Aplastic anemia (AA) is an immune-mediated and life-threatening form of acquired bone marrow failure (BMF), characterized by development and expansion of self-reactive T cells. These T cells cause continuous destruction of hematopoietic stem cells (HSCs), progenitors, and mature blood cells, leading to severe and if left untreated fatal marrow hypoplasia and pancytopenia. Standard treatment options for patients with AA include: (1) immunosuppressive therapy (IST) with anti-thymocyte globulin and cyclosporine A which targets self-reactive T cells, or (2) matched sibling or unrelated BM transplant (BMT). The IST treatment is often not effective due to poor response to therapy or disease relapse after IST. Also, BMT is not an option for many patients due to their age, comorbidities, and the lack of histocompatible donor. This necessitates development and testing of novel approaches to reduce severity of AA and to efficiently treat patients with refractory and relapsed AA. Immune-mediated AA was reproduced in animals, including mouse lymphocyte infusion models, which are used to study further etiology and pathophysiology of AA and test new drugs and approaches in treating and managing AA. In these mouse models the immune correlates and pathologic features of AA are strikingly similar to features of severe human AA. In this article we (a) briefly review standard and developing approaches for treating AA and (b) describe development and testing of novel treatment approach with a potential to safely reduce BM hypoplasia and significantly decrease the loss of HSCs in mouse lymphocyte infusion model of AA.

Enhanced adipogenicity of bone marrow mesenchymal stem cells in aplastic anemia

Fatty bone marrow (BM) and defective hematopoiesis are a pathologic hallmark of aplastic anemia (AA). We have investigated adipogenic and osteogenic potential of BM mesenchymal stem cells (BM-MSC) in 10 AA patients (08 males and 02 females) with median age of 37 years (range: 06 to 79 years) and in the same number of age and sex matched controls. It was observed that BM-MSC of AA patients had a morphology, phenotype, and osteogenic differentiation potential similar to control subjects but adipocytes differentiated from AA BM-MSC had a higher density and larger size of lipid droplets and they expressed significantly higher levels of adiponectin and FABP4 genes and proteins as compared to control BM-MSC (P < 0.01 for both). Thus our data shows that AA BM-MSC have enhanced adipogenicity, which may have an important implication in the pathogenesis of the disease.

Bone marrow mesenchymal stem cells from patients with aplastic anemia maintain functional and immune properties and do not contribute to the pathogenesis of the disease

Aplastic anemia is a life-threatening bone marrow failure disorder characterized by peripheral pancytopenia and marrow hypoplasia. The majority of cases of aplastic anemia remain idiopathic, although hematopoietic stem cell deficiency and impaired immune responses are hallmarks underlying the bone marrow failure in this condition. Mesenchymal stem/stromal cells constitute an essential component of the bone marrow hematopoietic microenvironment because of their immunomodulatory properties and their ability to support hematopoiesis, and they have been involved in the pathogenesis of several hematologic malignancies. We investigated whether bone marrow mesenchymal stem cells contribute, directly or indirectly, to the pathogenesis of aplastic anemia. We found that mesenchymal stem cell cultures can be established from the bone marrow of aplastic anemia patients and display the same phenotype and differentiation potential as their counterparts from normal bone marrow. Mesenchymal stem cells from aplastic anemia patients support the in vitro homeostasis and the in vivo repopulating function of CD34(+) cells, and maintain their immunosuppressive and anti-inflammatory properties. These data demonstrate that bone marrow mesenchymal stem cells from patients with aplastic anemia do not have impaired functional and immunological properties, suggesting that they do not contribute to the pathogenesis of the disease.

Mesenchymal stem cells from pediatric patients with aplastic anemia: isolation, characterization, adipogenic, and osteogenic differentiation

Aplastic anemia is a syndrome of bone marrow (BM) failure characterized by peripheral pancytopenia and marrow hypoplasia. Its exact pathophysiology is still not clear. Mesenchymal stem cells (MSCs) play an important role in providing the specialized BM microenvironment for hematopoietic stem cells survival and differentiation. MSCs were isolated from BM of five patients with aplastic anemia and five controls. MSCs were characterized by morphology and immunophenotyping. Their viability, proliferative capacity, and adipogenic as well as osteogenic differentiation potentials were assessed. MSCs from aplastic anemia patients and controls shared similar spindle-shaped morphology and surface marker expression. MSCs derived from patients with aplastic anemia showed lower viability (74.2 ± 4.44% vs. 97.0 ± 1.58, p < 0.0001) and slower expansion rate as indicated by smaller population doubling and smaller cumulative population doubling from passages 1 to 4 (0.70 ± 0.22 vs. 2.34 ± 0.84; p = 0.009). Besides, aplastic anemia MSCs had poor capacity to differentiate into adipocytic and osteocytic lineages.

Efficacy and safety of mesenchymal stromal cell treatment from related donors for patients with refractory aplastic anemia

BACKGROUND AIMS

This study evaluated the feasibility, safety and immunological effects of the intravenous administration of mesenchymal stromal cells (MSCs) from a related donor in patients with refractory aplastic anemia (AA).

METHODS

A mean of 6 × 10(5)/kg (range, 5.0-7.1 × 10(5)) MSCs were injected intravenously to 18 patients, including 14 patients with nonsevere AA and four patients with severe AA who were refractory to prior immunosuppressive treatment. The outcomes of patients treated with MSCs were evaluated and compared with a historic control cohort, including 18 patients with refractory AA.

RESULTS

Two patients had injection-related adverse events, including transient fever and headache. No major adverse events were reported during the follow-up period. An immunological analysis revealed an increased proportion of CD4(+)CD25(+) FOXP3(+)regulatory T cells in peripheral mononuclear cells. Following up for 1 year, six of 18 patients (33.3%) achieved a complete response or a partial response to MSC treatment. In six patients, two achieved a complete response including a recovery of three hematopoietic cell lines after MSCs therapy at days 88 and 92, two patients achieved only a red cell recovery with hemoglobin levels >100 g/L at days 30 and 48 and two patients had only a platelet recovery with a platelet count of >60 × 10(9)/L at days 54 and 81. In the control cohort, only one patient (5.56%) achieved a partial response during the follow-up period.

CONCLUSIONS

The data from the present study suggest that treatment with MSCs from a related donor may be a promising therapeutic strategy for patients with refractory AA. The trial has been registered at ClinicalTrials.gov: identifier NCT01305694.

Mesenchymal stem cells in immune-mediated bone marrow failure syndromes

Immune-mediated bone marrow failure syndromes (BMFS) are characterized by ineffective marrow haemopoiesis and subsequent peripheral cytopenias. Ineffective haemopoiesis is the result of a complex marrow deregulation including genetic, epigenetic, and immune-mediated alterations in haemopoietic stem/progenitor cells, as well as abnormal haemopoietic-to-stromal cell interactions, with abnormal release of haemopoietic growth factors, chemokines, and inhibitors. Mesenchymal stem/stromal cells (MSCs) and their progeny (i.e., osteoblasts, adipocytes, and reticular cells) are considered as key cellular components of the bone marrow haemopoietic niche. MSCs may interfere with haemopoietic as well as immune regulation. Evidence suggests that bone marrow MSCs may be involved in immune-mediated BMFS underlying pathophysiology, harboring either native abnormalities and/or secondary defects, caused by exposure to activated marrow components. This review summarizes previous as well as more recent information related to the biologic/functional characteristics of bone marrow MSCs in myelodysplastic syndromes, acquired aplastic anemia, and chronic idiopathic neutropenia.

Effect of kidney-reinforcing, blood-activating and stasis-removing recipes on adhesion molecule expression of bone marrow mesenchymal stem cells from chronic aplastic anemia patients

OBJECTIVE

To explore the effect of kidney-reinforcing, blood-activating and stasis-removing recipes on adhesion molecule expression of bone marrow mesenchymal stem cells (MSCs) from patients with chronic aplastic anemia (CAA).

METHODS

We used three Traditional Chinese Medicine recipes, namely a kidney-reinforcing recipe (KRR), blood-activating and stasis-removing recipe (BASRR), and kidney-reinforcing, blood-activating and stasis-removing recipe (KRBASRR), and a normal saline control to prepare herbal medicine serum in Sprague Dawley rats. Thirty CAA patients were enrolled in the experimental group, including 17 kidney-Yang deficient patients and 13 kidney-Yin deficient patients. Ten healthy individuals were included in the control group. MSCs were isolated from bone marrow samples, and the cell density was observed to measure their proliferation ability by microscopy on days 2, 7, and 14 after isolation. In addition, the expression of adhesion molecules of bone marrow MSCs (CD106, CD49d, CD31 and CD44) were detected by flow cytometry after 48 h of treatment with the four different herbal medicine serums.

RESULTS

The proliferation of MSCs from kidney-Yang deficient and kidney-Yin deficient patients was weaker than that of MSCs from the control group. The expression of all adhesion molecules of bone marrow MSCs from CAA patients was obviously lower than that in the control group (P < 0.01). The expression of CD49d and CD31 in MSCs from patients with a kidney-Yin deficiency was lower than in those with a kidney-yang deficiency (P < 0.05 and P < 0.01, respectively). For kidney-Yang deficient patients, CD31 expression in the KRBASRR group was significantly higher than that in the BASRR group (P < 0.01), while CD44 in the KRBASRR group was significantly higher than that in both KRR and BASRR groups (P < 0.01). For kidney-Yin deficient patients, CD106 and CD49d expression in the KRBASRR group was obviously higher than that in the KRR group (P < 0.05), while CD31 and CD44 expression in the KRBASRR group was significantly higher than that in both KRR and BASRR groups (P < 0.05 and P < 0.01, respectively).

CONCLUSION

The bone marrow microenvironment in CAA patients is abnormal. The effect of KRBASRR may be better than that of KRR and BASRR for kidney-Yang deficient and kidney-Yin deficient patients by improving the expression levels of MSC adhesion molecules.

Differential gene expression profile associated with the abnormality of bone marrow mesenchymal stem cells in aplastic anemia

Aplastic anemia (AA) is generally considered as an immune-mediated bone marrow failure syndrome with defective hematopoietic stem cells (HSCs) and marrow microenvironment. Previous studies have demonstrated the defective HSCs and aberrant T cellular-immunity in AA using a microarray approach. However, little is known about the overall specialty of bone marrow mesenchymal stem cells (BM-MSCs). In the present study, we comprehensively compared the biological features and gene expression profile of BM-MSCs between AA patients and healthy volunteers. In comparison with healthy controls, BM-MSCs from AA patients showed aberrant morphology, decreased proliferation and clonogenic potential and increased apoptosis. BM-MSCs from AA patients were susceptible to be induced to differentiate into adipocytes but more difficult to differentiate into osteoblasts. Consistent with abnormal biological features, a large number of genes implicated in cell cycle, cell division, proliferation, chemotaxis and hematopoietic cell lineage showed markedly decreased expression in BM-MSCs from AA patients. Conversely, more related genes with apoptosis, adipogenesis and immune response showed increased expression in BM-MSCs from AA patients. The gene expression profile of BM-MSCs further confirmed the abnormal biological properties and provided significant evidence for the possible mechanism of the destruction of the bone marrow microenvironment in AA.

Effects of sodium copper chlorophyllin on mesenchymal stem cell function in aplastic anemia mice

OBJECTIVE

To investigate the effects of sodium copper chlorophyllin (SCC) on the proliferation, differentiation and immunomodulatory function of mesenchymal stem cells (MSCs) from mice with aplastic anemia.

METHODS

A mouse model of aplastic anemia was established by exposure of BALB/c mice to sublethal doses of 5.0 Gy Co60 γ radiation, followed by transplantation of 2×10(6) lymph node cells from DBA/2 donor mice within 4 h after radiation. Aplastic anemic BALB/c mice were randomly divided into six groups: the treated groups, which received 25, 50, or 100 mg/kg/day SCC, respectively; a positive control group treated with cyclosporine A (CsA); and an untreated model control group (model group); while, the non-irradiated mice as the normal control group. SCC or CsA were administered by gastrogavage for 20 days, starting on day 4 after irradiation. Peripheral blood cells were counted and colony-forming fibroblasts (CFU-F) in the bone marrow were assayed. The ability of MSCs to form calcium nodes after culture in osteoinductive medium was also observed. The immunosuppressive effect of MSCs on T lymphocytes was analyzed by enzyme-linked immunosorbent assay and flow cytometry, to evaluate the efficacy of SCC in mice with aplastic anemia.

RESULTS

Peripheral blood white cell and platelet counts were increased by medium and high SCC doses, compared with the untreated control. CFU-Fs were also increased compared with the untreated control, and the numbers of calcium nodes in MSCs in osteoinductive medium were elevated in response to SCC treatment. The percentage of Forkhead box protein 3 (FOXP3(+)) T cells was increased in T cell-MSC cocultures, and the cytokine transforming growth factor β1 was up-regulated in SCC-treated groups.

CONCLUSION

The results of this study suggest that SCC not only promotes the proliferation and differentiation of MSCs, but also improves their immunoregulatory capacity in mice with aplastic anemia.

Genetic associations in acquired immune-mediated bone marrow failure syndromes: insights in aplastic anemia and chronic idiopathic neutropenia

Increasing interest on the field of autoimmune diseases has unveiled a plethora of genetic factors that predispose to these diseases. However, in immune-mediated bone marrow failure syndromes, such as acquired aplastic anemia and chronic idiopathic neutropenia, in which the pathophysiology results from a myelosuppressive bone marrow microenvironment mainly due to the presence of activated T lymphocytes, leading to the accelerated apoptotic death of the hematopoietic stem and progenitor cells, such genetic associations have been very limited. Various alleles and haplotypes of human leucocyte antigen (HLA) molecules have been implicated in the predisposition of developing the above diseases, as well as polymorphisms of inhibitory cytokines such as interferon-γ, tumor necrosis factor-α, and transforming growth factor-β1 along with polymorphisms on molecules of the immune system including the T-bet transcription factor and signal transducers and activators of transcription. In some cases, specific polymorphisms have been implicated in the outcome of treatment on those patients.

Intrinsic impairment of CD4+CD25+ regulatory T cells in acquired aplastic anemia

Acquired aplastic anemia (AA) is an immune-mediated bone marrow (BM) failure attacked by autoreactive effector T cells and BM is the main target organ. CD4+CD25+ regulatory T cells (Tregs) were believed to control development and progression of autoimmunity by suppressing autoreactive effector T cells, but little was known regarding the function of Tregs in AA. Our study demonstrated that both peripheral blood (PB) and BM had decreased frequencies of Tregs, accompanied with a reversed lower ratio of Treg frequencies between BM and PB in AA. PB Tregs in AA had impaired migratory ability because of lower CXCR4 (but not for CXCR7) expression. Interestingly, we first showed that impairment of Treg-mediated immunosuppression was intrinsic to Tregs, rather than resistance of effector T cells to suppression in AA by coculture assays and criss-cross experiments in vitro. Furthermore, Tregs in AA were less able to inhibit interferon-γ production by effector T cells. Defective immunosuppression by Tregs could contribute to impaired hematopoiesis conducted by effector T cells in vitro. Our study provided powerful evidence that impairment of Tregs played a critical role in the pathophysiology of AA. Thus, patients with AA might greatly benefit from a Treg-oriented immunosuppressive strategy.

Impaired immunomodulatory ability of bone marrow mesenchymal stem cells on CD4(+) T cells in aplastic anemia

Aplastic anemia (AA) is a marrow failure syndrome mediated by aberrant T-cell subsets. Mesenchymal stem cells (MSCs) play an important role in maintaining immune homeostasis through modulating a variety of immune cells. However, little is known about the immunomodulation potential of bone marrow MSCs (BM-MSCs) in AA. Here, we reported that BM-MSCs from AA patients were reduced in suppressing the proliferation and clonogenic potential of CD4(+) T cells and the production of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ), which was associated with decreased prostaglandin E2 (PGE2). Meanwhile, BM-MSCs from AA patients were defective to promote CD4(+)CD25(+)FOXP3(+) regulatory T cells expansion through reduced transforming growth factor-β (TGF-β). No significant difference between AA and normal BM-MSCs was observed in affecting the production of interleukins (IL)-4, IL-10 and IL-17. Our data indicate that BM-MSCs were impaired in maintaining the immune homeostasis associated with CD4(+) T cells, which might aggravate the marrow failure in AA.

Interleukin-27 enhances the production of tumour necrosis factor-α and interferon-γ by bone marrow T lymphocytes in aplastic anaemia

Aplastic anaemia (AA) is considered as an immune-mediated bone marrow failure syndrome. The mechanism is involved with a variety of immune molecules including interferon-γ (IFN-γ), tumour necrosis factor-α (TNF-α) and interleukins (ILs). IL-27 is a novel member of the IL-12 family, which mediates T cell response and enhances the production of IFN-γ. However, little is known about the role of IL-27 in the development of AA. This study investigated the role of IL-27 and its receptor IL-27R in the pathogenesis of AA. Both the mRNA expression of IL-27/IL-27R subunits in the bone marrow mononuclear cells (BMMNCs) and the levels of IL-27 in the marrow plasma in AA were found to be higher than in controls. Increased IL-27 correlated with the disease severity of AA. Subsequently, we stimulated marrow T lymphocytes with recombinant human (rh)IL-27 and found that rhIL-27 enhanced the production of TNF-α and IFN-γ in both CD4(+) and CD8(+) T lymphocytes from AA patients. We also detected increased TNF-α and IFN-γ in the supernatants of BMMNCs from AA patients after IL-27 stimulation. In conclusion, our data suggest that elevated IL-27 and IL-27-induced TNF-α and IFN-γ overproduction might be involved in the pathogenesis of AA.