MicroRNAs of bone marrow mesenchymal stem cell-derived exosomes regulate acute myeloid leukemia cell proliferation and apoptosis / 中华医学杂志(英文版)

BACKGROUND@#Acute myeloid leukemia (AML) is a malignant hematological disease, originating from hematopoiesis stem cell differentiation obstruction and clonal proliferation. New reagents or biologicals for the treatment of AML are urgently needed, and exosomes have been identified as candidate biomarkers for disease diagnosis and prognosis. This study aimed to investigate the effects of exosomes from bone marrow mesenchymal stem cells (BMSCs) on AML cells as well as the underlying microRNA (miRNA)-mediated mechanisms.@*METHODS@#Exosomes were isolated using a precipitation method, followed by validation using marker protein expression and nanoparticle tracking analysis. Differentially expressed miRNAs were identified by deep RNA sequencing and confirmed by quantitative real-time polymerase chain reaction (qPCR). Cell proliferation was assessed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt method, and cell cycle progression and apoptosis were detected by flow cytometry. Functional gene expression was analyzed by qPCR and Western blotting (WB). Significant differences were determined using Student's t test or analysis of variance.@*RESULTS@#BMSCs-derived exosomes effectively suppressed cell proliferation (both P < 0.0001 at 10 and 20 μg/mL) and cell cycle progression (P < 0.01 at G0-G1 stage), and also significantly enhanced cell apoptosis (P < 0.001) in KG-1a cells. There were 1167 differentially expressed miRNAs obtained from BMSCs-derived exosomes compared with KG-1a cell-derived exosomes (P < 0.05). Knockdown of hsa-miR-124-5p in BMSCs abrogated the effects of BMSCs-derived exosomes in regulating KG-1a such as the change in cell proliferation (both P < 0.0001 vs. normal KG-1a cell [NC] at 48 and 72 h). KG-1a cells treated with BMSCs-derived exosomes suppressed expression of structural maintenance of chromosomes 4 (P < 0.001 vs. NC by qPCR and P < 0.0001 vs. NC by WB), which is associated with the progression of various cancers. This BMSCs-derived exosomes effect was significantly reversed with knockdown of hsa-miR-124-5p (P < 0.0001 vs. NC by WB).@*CONCLUSIONS@#BMSCs-derived exosomes suppress cell proliferation and cycle progression and promote cell apoptosis in KG-1a cells, likely acting through hsa-miR-124-5p. Our study establishes a basis for a BMSCs-derived exosomes-based AML treatment.

Antigen-loaded dendritic cells trigger killing effects of specific cytotoxic T lymphocytes on Jurkat cells in vitro / 中国实验血液学杂志

This study was aimed to investigate the effects of tumor antigen-loaded dendritic cells (DC) stimulating the specific cytotoxic T lymphocytes (CTL) on Jurkat cells in vitro. Peripheral blood mononuclear cells were isolated by Ficoll density gradient centrifugation from normal human heparinized blood, the adherent monocytes were cultured with granulocyte-macrophage colony stimulating factor (GM-CSF), interleukin-4 (IL-4), alpha tumor necrosis factor (TNF-alpha) and sCD40L, DCs were co-cultured with frozen-thawed antigen of Jurkat cells or WT1 peptides, and then T cells were triggered into specific CTL. The results showed that most suspended cells exhibited distinctive morphological features of DC which expressed CD40 (96%), CD86 (97%), CD80 (77%), CD1a (69%), and gained the powerful capacity to stimulate proliferation of allogeneic lymphocytes. Under the effector: target ratio of 20:1, CTLs derived from cultures with DC and frozen-thawed antigen of Jurkat cells showed 91.1% cytotoxicity against Jurkat cells, CTL derived from cultures with DC and WT1 peptides showed 87.5% cytotoxicity against Jurkat cells, cytotoxicity of CTL derived from cultures with unloaded DC against Jurkat cells was 42.1% and cytotoxicity of monocytes was 22.7%. Cytotoxicity of CTL derived from culture with frozen-thawed antigen or WT1 peptides loaded DC was stronger than that in control groups (P < 0.01). It is concluded that the tumor antigen-pulsed DC can induce efficient and specific anti-tumor immunity, may play a great role in clinical therapy for leukemia.