Effect of intravenous coadministration of human stroma cell lines on engraftment of long-term repopulating clonal myelodysplastic syndrome cells in immunodeficient mice

The non-cell-autonomous function of ID1 promotes AML progression via ANGPTL7 from the microenvironment

The bone marrow microenvironment (BMM) can regulate leukemia stem cells (LSCs) via secreted factors. Increasing evidence suggests that dissecting the mechanisms by which the BMM maintains LSCs may lead to the development of effective therapies for the eradication of leukemia. Inhibitor of DNA binding 1 (ID1), a key transcriptional regulator in LSCs, previously identified by us, controls cytokine production in the BMM, but the role of ID1 in acute myeloid leukemia (AML) BMM remains obscure. Here, we report that ID1 is highly expressed in the BMM of patients with AML, especially in BM mesenchymal stem cells, and that the high expression of ID1 in the AML BMM is induced by BMP6, secreted from AML cells. Knocking out ID1 in mesenchymal cells significantly suppresses the proliferation of cocultured AML cells. Loss of Id1 in the BMM results in impaired AML progression in AML mouse models. Mechanistically, we found that Id1 deficiency significantly reduces SP1 protein levels in mesenchymal cells cocultured with AML cells. Using ID1-interactome analysis, we found that ID1 interacts with RNF4, an E3 ubiquitin ligase, and causes a decrease in SP1 ubiquitination. Disrupting the ID1-RNF4 interaction via truncation in mesenchymal cells significantly reduces SP1 protein levels and delays AML cell proliferation. We identify that the target of Sp1, Angptl7, is the primary differentially expression protein factor in Id1-deficient BM supernatant fluid to regulate AML progression in mice. Our study highlights the critical role of ID1 in the AML BMM and aids the development of therapeutic strategies for AML.

Engineering tandem CD33xCD146 CAR CIK (cytokine-induced killer) cells to target the acute myeloid leukemia niche

In acute myeloid leukemia (AML), malignant stem cells hijack the normal bone marrow niche where they are largely protected from the current therapeutic approaches. Thus, eradicating these progenitors is the ultimate challenge in the treatment of this disease. Specifically, the development of chimeric antigen receptors (CARs) against distinct mesenchymal stromal cell subpopulations involved in the maintenance of leukemic stem cells within the malignant bone marrow microenvironment could represent a new strategy to improve CAR T-cell therapy efficacy, which is still unsuccessful in AML. As a proof of concept, we generated a novel prototype of Tandem CAR, with one specificity directed against the leukemic cell marker CD33 and the other against the mesenchymal stromal cell marker CD146, demonstrating its capability of simultaneously targeting two different cell types in a 2D co-culture system. Interestingly, we could also observe an in vitro inhibition of CAR T cell functionality mediated by stromal cells, particularly in later effector functions, such as reduction of interferon-gamma and interleukin-2 release and impaired proliferation of the CAR⁺ effector Cytokine-Induced Killer (CIK) cells. Taken together, these data demonstrate the feasibility of a dual targeting model against two molecules, which are expressed on two different target cells, but also highlight the immunomodulatory effect on CAR CIK cells exerted by stromal cells, confirming that the niche could be an obstacle to the efficacy of CAR T cells. This aspect should be considered in the development of novel CAR T cell approaches directed against the AML bone marrow niche.

LacNAc modification in bone marrow stromal cells enhances resistance of myelodysplastic syndrome cells to chemotherapeutic drugs

Chemotherapeutic drugs are used routinely for treatment for myelodysplastic syndrome (MDS) patients but are ineffective in a substantial proportion of patients. Abnormal hematopoietic microenvironments, in addition to spontaneous characteristics of malignant clones, contribute to ineffective hematopoiesis. In our study, we found expression of enzyme β1,4-galactosyltransferase 1 (β4GalT1), which regulates N-acetyllactosamine (LacNAc) modification of proteins, is elevated in bone marrow stromal cells (BMSCs) of MDS patients, and also contributes to drug ineffectiveness through a protective effect on malignant cells. Our investigation of the underlying molecular mechanism revealed that β4GalT1-overexpressing BMSCs promoted MDS clone cells resistant to chemotherapeutic drugs and also showed enhanced secretion of cytokine CXCL1 through degradation of tumor protein p53. Chemotherapeutic drug tolerance of myeloid cells was inhibited by application of exogenous LacNAc disaccharide and blocking of CXCL1. Our findings clarify the functional role of β4GalT1-catalyzed LacNAc modification in BMSCs of MDS. Clinical alteration of this process is a potential new strategy that may substantially enhance effectiveness of therapies for MDS and other malignancies, by targeting a niche interaction.

Immune Dysfunction, Cytokine Disruption, and Stromal Changes in Myelodysplastic Syndrome: A Review

Myelodysplastic syndromes (MDS) are myeloid neoplasms characterized by bone marrow dysfunction and increased risk of transformation to leukemia. MDS represent complex and diverse diseases that evolve from malignant hematopoietic stem cells and involve not only the proliferation of malignant cells but also the dysfunction of normal bone marrow. Specifically, the marrow microenvironment-both hematopoietic and stromal components-is disrupted in MDS. While microenvironmental disruption has been described in human MDS and murine models of the disease, only a few current treatments target the microenvironment, including the immune system. In this review, we will examine current evidence supporting three key interdependent pillars of microenvironmental alteration in MDS-immune dysfunction, cytokine skewing, and stromal changes. Understanding the molecular changes seen in these diseases has been, and will continue to be, foundational to developing effective novel treatments that prevent disease progression and transformation to leukemia.

Chimerism, the Microenvironment and Control of Leukemia

Transplantation of allogeneic hematopoietic cells faces two barriers: failure of engraftment due to a host versus graft reaction, and the attack of donor cells against the patient, the graft versus host (GVH) reaction. This reaction may lead to GVH disease (GVHD), but in patients transplanted due to leukemia or other malignant disorders, this may also convey the benefit of a graft versus leukemia (GVL) effect. The interplay of transplant conditioning with donor and host cells and the environment in the patient is complex. The microbiome, particularly in the intestinal tract, profoundly affects these interactions, directly and via soluble mediators, which also reach other host organs. The microenvironment is further altered by the modifying effect of malignant cells on marrow niches, favoring the propagation of the malignant cells. The development of stable mixed donor/host chimerism has the potential of GVHD prevention without necessarily increasing the risk of relapse. There has been remarkable progress with novel conditioning regimens and selective T-cell manipulation aimed at securing engraftment while preventing GVHD without ablating the GVL effect. Interventions to alter the microenvironment and change the composition of the microbiome and its metabolic products may modify graft/host interactions, thereby further reducing GVHD, while enhancing the GVL effect. The result should be improved transplant outcome.

HS-5 and HS-27A Stromal Cell Lines to Study Bone Marrow Mesenchymal Stromal Cell-Mediated Support to Cancer Development

In this study, we compared the overall gene and pathway expression profiles of HS-5 and HS-27A stromal cell lines with those of primary bone marrow MSCs to verify if they can be considered a reliable alternative tool for evaluating the contribution of MSCs in tumor development and immunomodulation. Indeed, due to their easier manipulation in vitro as compared to primary MSC cultures, several published studies took advantage of stromal cell lines to assess the biological mechanisms mediated by stromal cells in influencing tumor biology and immune responses. However, the process carried out to obtain immortalized cell lines could profoundly alter gene expression profile, and consequently their biological characteristics, leading to debatable results. Here, we evaluated the still undisclosed similarities and differences between HS-5, HS-27A cell lines and primary bone marrow MSCs in the context of tumor development and immunomodulation. Furthermore, we assessed by standardized immunological assays the capability of the cell lines to reproduce the general mechanisms of MSC immunoregulation. We found that only HS-5 cell line could be suitable to reproduce not only the MSC capacity to influence tumor biology, but also to evaluate the molecular mechanisms underlying tumor immune escape mediated by stroma cells. However, HS-5 pre-treatment with inflammatory cytokines, that normally enhances the immunosuppressive activity of primary MSCs, did not reproduce the same MSCs behavior, highlighting the necessity to accurately set up in vitro assays when HS-5 cell line is used instead of its primary counterpart.

Screening differentially expressed proteins from co-cultured hematopoietic cells and bone marrow-derived stromal cells by quantitative proteomics (SILAC) method

Background

Bone marrow stromal cells protect hematopoietic cells and provide drug resistance by delivering bunch of variable proteins. Thus, alterations of protein expression are typically associated with cell–cell signal transduction and regulation of cellular functions.

Methods

Co-culture models of bone marrow stromal cells and hematopoietic cells are often used in studies of their crosstalk. Studies of altered protein expression initiated by stromal cell/hematopoietic cell interactions are an important new trend in microenvironmental research. There has been no report to date of global quantitative proteomics analysis of crosstalk between hematopoietic cells and stromal cells. In this study, we analyzed quantitative proteomes in a co-culture system of stromal HS5 cells and hematopoietic KG1a cells, and simultaneously tracked differentially expressed proteins in two types of cells before and after co-culture by stable isotope labeling by amino acids in cell culture (SILAC) method.

Results

We have shown that in co-cultured KG1a, 40 proteins (including CKAP4, LMNA, and SERPINB2) were upregulated and 64 proteins (including CD44, CD99, and NCAM1) were downregulated relative to KG1a alone. We utilized IPA analysis to discover that the NOD-like receptor signaling pathway was upregulated, whereas platelet activation was downregulated in co-cultured KG1a cells. Furthermore, 95 proteins (including LCP1, ARHGAP4, and UNCX) were upregulated and 209 proteins (including CAPG, FLNC, and MAP4) were downregulated in co-cultured HS5 relative to HS5 alone. The tight junction pathway was downregulated and glycolysis/gluconeogenesis pathway was dysfunctional in co-cultured HS5. Most importantly, the significantly differentially expressed proteins can also be confirmed using different co-cultured cell lines.

Conclusion

Altogether, we recommend such quantitative proteomics approach for the studies of the hematopoietic–stroma cross-talk, differentially expressed proteins and related signaling pathways identification. The differentially expressed proteins identified from this current SILAC method will provide a useful basis for ongoing studies of crosstalk between stromal cells and hematopoietic cells in co-culture systems. All these result suggested our ongoing studies can focus on the mechanisms underlying CKAP4 increase and CD44 decrease in co-cultured hematopoietic cells, and the increase of LCP1 and decrease of CAPG in co-cultured stromal cell. The proteomic profiles from the KG1a/stromal cell co-culture system give new molecular insights into the roles of these cells in MDS pathophysiology and related bone disease.

Electronic supplementary material

The online version of this article (10.1186/s12014-019-9249-x) contains supplementary material, which is available to authorized users.

Molecular dissection of engraftment in a xenograft model of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are oligoclonal disorders of the hematopoietic stem cells (HSC). Recurrent gene mutations are involved in the MDS physiopathology along with the medullar microenvironment. To better study the heterogeneity of MDS, it is necessary to create patient derived xenograft (PDX).

We have reproduced a PDX model by xenografting HSC (CD34⁺) and mesenchymal stromal cells (MSC) in NOD/SCID/IL2rγ^-/- mice with primary samples from one RAEB2, two RAEB1 and one RARS patients harboring karyotype abnormalities and gene mutations. The average human chimerisms ranged from 59.7% to 0.0175% for the 4 patients. Secondary grafts (G2) were only performed for mice derived from the RAEB2 patient and the average human chimerism was 53.33%. G1 mice 1 and 2, and their derived G2 mice showed less than 20% of medullar blasts whereas mouse 3 and the resulting G2 mice transformed to AML. Clonal architecture was dissected in the different hematopoietic progenitors (HP) harvested from G1 and G2 mice. By direct Sanger sequencing, we found the 4 initial mutations in each HP subpopulation and those mutations had the same variant allele frequency in the CD34⁺ CD38^- HSC from G1 and G2 mice by next generation sequencing (NGS). Targeted NGS analysis done in HSC of mouse 3 did not show any additional driver gene mutations explaining the transformation to AML.

To conclude, we have generated a PDX mouse model that perfectly reproduces the MDS founder clone which is stable over time, allowing us to consider this system as a powerful tool to test therapeutic approaches.

The microenvironment in myelodysplastic syndromes: Niche-mediated disease initiation and progression

Myelodysplastic syndromes (MDSs) are clonal disorders of hematopoietic stem and progenitor cells and represent the most common cause of acquired marrow failure. Hallmarked by ineffective hematopoiesis, dysplastic marrow, and risk of transformation to acute leukemia, MDS remains a poorly treated disease. Although identification of hematopoietic aberrations in human MDS has contributed significantly to our understanding of MDS pathogenesis, evidence now identify the bone marrow microenvironment (BMME) as another key contributor to disease initiation and progression. With improved understanding of the BMME, we are beginning to refine the role of the hematopoietic niche in MDS. Despite genetic diversity in MDS, interaction between MDS and the BMME appears to be a common disease feature and therefore represents an appealing therapeutic target. Further understanding of the interdependent relationship between MDS and its niche is needed to delineate the mechanisms underlying hematopoietic failure and how the microenvironment can be targeted clinically. This review provides an overview of data from human MDS and murine models supporting a role for BMME dysfunction at several steps of disease pathogenesis. Although no models or human studies so far have combined all of these findings, we review current data identifying BMME involvement in each step of MDS pathogenesis organized to reflect the chronology of BMME contribution as the normal hematopoietic system becomes myelodysplastic and MDS progresses to marrow failure and transformation. Although microenvironmental heterogeneity and dysfunction certainly add complexity to this syndrome, data are already demonstrating that targeting microenvironmental signals may represent novel therapeutic strategies for MDS treatment.

Quantitative proteomic analysis and comparison of two bone marrow stromal cell lines using the SILAC method

Two human bone marrow stromal cell lines, HS5 and HS27a, co-cultured with myeloid cells, have frequently been used in studies of cross talk between cells in the bone marrow microenvironment and hematopoietic cells. Altered expression of proteins is typically associated with cell-cell signal transduction and regulation of cellular functions. Many studies have focused on key proteins that contribute to functional differences in cell co-culture models, but global quantitative proteome analysis of HS5 and HS27a has not been performed. We employed the stable isotope labeling by amino acids in cell culture (SILAC) method using two stable isotopes each of arginine and lysine to label proteins in the two cell lines. Labeled proteins were analyzed by 2-D ultrahigh-resolution liquid chromatography- LTQ/Orbitrap mass spectrometry. Among 4,213 unique identified and annotated proteins in the cell lines, 1,462 were detected in two independent experiments. Of these, 69 exhibited significant upregulation and 48 significant downregulation (>95% confidence) in HS27a relative to HS5 cells. Gene ontology term and pathway analysis indicated that the differentially regulated proteins were involved in cellular movement, cell-to-cell signaling and interaction, and hematologic system development and function. A total of 55 items were identified in both genomic and proteomic databases. Quantitative reverse transcription polymerase chain reaction and Western blotting were performed on 7 proteins randomly selected from 28 differentially expressed proteins that were identified in both databases and were involved in the top networks/pathways. We observed a decrease in apoptosis in co-cultured KG1a cells when integrin αV was inhibited in HS27a cells, which suggested the functional role of integrin αV in the co-culture system. The integrated genomic/proteomic approach described here, and the identified proteins, will provide a useful basis for further elucidation of molecular mechanisms in the bone marrow microenvironment and for ongoing studies of cross talk among stromal cells and myeloma cells in co-culture systems.

Mesenchymal Stem and Progenitor Cells in Normal and Dysplastic Hematopoiesis-Masters of Survival and Clonality?

Myelodysplastic syndromes (MDS) are malignant hematopoietic stem cell disorders that have the capacity to progress to acute myeloid leukemia (AML). Accumulating evidence suggests that the altered bone marrow (BM) microenvironment in general, and in particular the components of the stem cell niche, including mesenchymal stem cells (MSCs) and their progeny, play a pivotal role in the evolution and propagation of MDS. We here present an overview of the role of MSCs in the pathogenesis of MDS, with emphasis on cellular interactions in the BM microenvironment and related stem cell niche concepts. MSCs have potent immunomodulatory capacities and communicate with diverse immune cells, but also interact with various other cellular components of the microenvironment as well as with normal and leukemic stem and progenitor cells. Moreover, compared to normal MSCs, MSCs in MDS and AML often exhibit altered gene expression profiles, an aberrant phenotype, and abnormal functional properties. These alterations supposedly contribute to the “reprogramming” of the stem cell niche into a disease-permissive microenvironment where an altered immune system, abnormal stem cell niche interactions, and an impaired growth control lead to disease progression. The current article also reviews molecular targets that play a role in such cellular interactions and possibilities to interfere with abnormal stem cell niche interactions by using specific targeted drugs.

Insights into myelodysplastic syndromes from current preclinical models

In recent years, there has been significant progress made in our understanding of the molecular genetics of myelodysplastic syndromes (MDS). Using massively parallel sequencing techniques, recurring mutations are identified in up to 80% of MDS cases, including many with a normal karyotype. The differential role of some of these mutations in the initiation and progression of MDS is starting to be elucidated. Engineering candidate genes in mice to model MDS has contributed to recent insights into this complex disease. In this review, we examine currently available mouse models, with detailed discussion of selected models. Finally, we highlight some advances made in our understanding of MDS biology, and conclude with discussions of questions that remain unanswered.

Quantitative analysis of glycans, related genes, and proteins in two human bone marrow stromal cell lines using an integrated strategy

Altered expression of glycans is associated with cell-cell signal transduction and regulation of cell functions in the bone marrow micro-environment. Studies of this micro-environment often use two human bone marrow stromal cell lines, HS5 and HS27a, co-cultured with myeloid cells. We hypothesized that differential protein glycosylation between these two cell lines may contribute to functional differences in in vitro co-culture models. In this study, we applied an integrated strategy using genomic, proteomic, and functional glycomic techniques for global expression profiling of N-glycans and their related genes and enzymes in HS5 cells versus HS27a cells. HS5 cells had significantly enhanced levels of bisecting N-glycans (catalyzed by MGAT3 [β-1,4-mannosyl-glycoprotein 4-β-N-acetylglucosaminyltransferase]), whereas HS27a cells had enhanced levels of Galβ1,4GlcNAc (catalyzed by β4GalT1 [β4-galactosyltransferase I]). This integrated strategy provides useful information regarding the functional roles of glycans and their related glycogenes and glycosyltransferases in the bone marrow microenvironment, and a basis for future studies of crosstalk among stromal cells and myeloma cells in co-culture.

Biology of BM failure syndromes: role of microenvironment and niches

The BM microenvironment and its components regulate hematopoietic stem and progenitor cell (HSC) fate. An abnormality in the BM microenvironment and specific dysfunction of the HSC niche could play a critical role in initiation, disease progression, and response to therapy of BM failure syndromes. Therefore, the identification of changes in the HSC niche in BM failure syndromes should lead to further knowledge of the signals that disrupt the normal microenvironment. In turn, niche disruption may contribute to disease morbidity, resulting in pancytopenia and clonal evolution, and its understanding could suggest new therapeutic targets for these conditions. In this chapter, we briefly review the evidence for the importance of the BM microenvironment as a regulator of normal hematopoiesis, summarize current knowledge regarding the role of dysfunctions in the BM microenvironment in BM failure syndromes, and propose a strategy through which niche stimulation can complement current treatment for myelodysplastic syndrome.

Murine xenogeneic models of myelodysplastic syndrome: an essential role for stroma cells

The objective of is this article is to review murine xenotransplantation models for myelodysplastic syndromes (MDS). The difficulties in achieving sustained engraftment of MDS cells in immunodeficient mice may lie in innate characteristics of the MDS clones and microenvironmental factors. Engraftment of very low numbers of CD45(+) clonal MDS cells has been achieved with intravenous injection; higher rates of engraftment are obtained via the intramedullary route. Coinjection of certain stroma components with hematopoietic cells overcomes limitations of intravenous (IV) administration, allowing for engraftment of high proportions of human CD45(+) cells in mouse spleen and marrow. Expression of CD146 on stroma cells conveys an engraftment-facilitating effect. Clonal MDS cells have been propagated for periods beyond 6 months and have been transplanted successfully into secondary recipients. Engraftment of human clonal MDS cells with stem cell characteristics in immunodeficient mice is greatly facilitated by coinjection of stroma/mesenchymal cells, particularly with IV administration. CD146 expression on stroma is an essential factor; however, no model develops the laboratory and clinical features of human MDS. Additional work is needed to determine cellular and noncellular factors required for the full evolution of MDS.

Stem cell origin of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are common hematologic disorders that are characterized by decreased blood counts due to ineffective hematopoiesis. MDS is considered a 'preleukemic' disorder linked to a significantly elevated risk of developing an overt acute leukemia. Cytopenias can be observed in all three myeloid lineages suggesting the involvement of multipotent, immature hematopoietic cells in the pathophysiology of this disease. Recent studies using murine models of MDS as well as primary patient-derived bone marrow samples have provided direct evidence that the most immature, self-renewing hematopoietic stem cells (HSC), as well as lineage-committed progenitor cells, are critically altered in patients with MDS. Besides significant changes in the number and distribution of stem as well as immature progenitor cells, genetic and epigenetic aberrations have been identified, which confer functional changes to these aberrant stem cells, impairing their ability to proliferate and differentiate. Most importantly, aberrant stem cells can persist and further expand after treatment, even upon transient achievement of clinical complete remission, pointing to a critical role of these cells in disease relapse. Ongoing preclinical and clinical studies are particularly focusing on the precise molecular and functional characterization of aberrant MDS stem cells in response to therapy, with the goal to develop stem cell-targeted strategies for therapy and disease monitoring that will allow for achievement of longer-lasting remissions in MDS.