Functional inhibition of mesenchymal stromal cells in acute myeloid leukemia

Abstract

Hematopoietic insufficiency is the hallmark of acute myeloid leukemia (AML) and predisposes patients to life-threatening complications such as bleeding and infections. Addressing the contribution of mesenchymal stromal cells (MSC) to AML-induced hematopoietic failure we show that MSC from AML patients (n = 64) exhibit significant growth deficiency and impaired osteogenic differentiation capacity. This was molecularly reflected by a specific methylation signature affecting pathways involved in cell differentiation, proliferation and skeletal development. In addition, we found distinct alterations of hematopoiesis-regulating factors such as Kit-ligand and Jagged1 accompanied by a significantly diminished ability to support CD34+ hematopoietic stem and progenitor cells in long-term culture-initiating cells (LTC-ICs) assays. This deficient osteogenic differentiation and insufficient stromal support was reversible and correlated with disease status as indicated by Osteocalcin serum levels and LTC-IC frequencies returning to normal values at remission. In line with this, cultivation of healthy MSC in conditioned medium from four AML cell lines resulted in decreased proliferation and osteogenic differentiation. Taken together, AML-derived MSC are molecularly and functionally altered and contribute to hematopoietic insufficiency. Inverse correlation with disease status and adoption of an AMLlike phenotype after exposure to leukemic conditions suggests an instructive role of leukemic cells on bone marrow microenvironment.

Transforming growth factor β1-mediated functional inhibition of mesenchymal stromal cells in myelodysplastic syndromes and acute myeloid leukemia

“…Along with impaired stromal support of healthy HSPC this suggests that MSC alterations contribute substantially to the inadequate hematopoiesis in MDS and AML. 12,13 Furthermore, these findings imply significantly deregulated bi-directional crosstalk between malignant myeloid cells and MSC. In the current analysis, we used discovery-based strategies, such as RNA sequencing, followed by candidate-testing approaches.…”

“…12,13 All experiments were carried out using MSC derived from passages 3–4. Furthermore, CD34 + HSPC were obtained from the bone marrow of healthy controls by density gradient separation and subsequent immunomagnetic selection (Miltenyi Biotec, Bergisch Gladbach, Germany) as described elsewhere.…”

“…For quantification of growth potential, absolute cell numbers and cumulative population doubling were determined as described elsewhere. 12,13 Furthermore, surface expression of established stromal cell markers CD73, CD90 and CD105, 30 hematopoietic antigens CD34 and CD45 as well as Jagged1 were measured by flow cytometry using a FACSCalibur (BD Biosciences, Heidelberg, Germany) and FCS Express V3 software (De Novo Software, Los Angeles, CA, USA) for data analysis. Antibody specifications are provided in Online Supplementary Table S2 .…”

Hypomethylating agents for treatment and prevention of relapse after allogeneic blood stem cell transplantation

“…We have recently demonstrated that mesenchymal stromal cells from patients with MDS and AML are aberrantly methylated [60][61][62]. Along with this, Verma et al showed that Aza might mediate at least some of its efficacy via demethylation of the BM stroma [3].…”

Acute myeloid leukemia cells polarize macrophages towards a leukemia supporting state in a Growth factor independence 1 dependent manner

“…15 This might enhance the LSCs quiescence, leading to chemotherapy resistance. 1,[16][17][18][19] A recent study reported that the inhibition of SIRPα signalling in macrophages impairs engraftment of human LSCs in immunocompromised NSG mice. 20 Clinically, the accumulation of TAMs in the lymph nodes of patients with classic Hodgkin lymphoma was associated with a poor prognosis.…”