The effect of microvesicles derived from K562 cells on proliferation and apoptosis of human bone marrow mesenchymal stem cells.

Objectives: Microvesicles (MVs) are small membrane-bound particles that act as a vehicle to transfer their contents, such as proteins, RNAs, and miRNAs, to the target cells, making them undergo several changes. Depending on the origin and the target cell, MVs may cause cell survival or apoptosis. This study investigated the effects of MVs released from the leukemic K562 cell line on the human bone marrow mesenchymal stem cells (hBM-MSCs) to evaluate changes in the survival or apoptosis of the cells in an in vitro system. Materials and Methods: In this experimental study, we added the isolated MVs from the K562 cell line to hBM-MSCs, and after three and then seven days, subsequently cell count, cell viability, transmission electron microscopy, tracing MVs by carboxyfluorescein diacetate, succinimidyl ester (CFSE) solution, flow cytometry analysis for Annexin-V/PI staining and qPCR for the evaluation of BCL-2, KI67, and BAX expression were carried out. On the 10th day of the culture, hBM-MSCs were examined by Oil red O and Alizarin Red staining to evaluate their differentiation into adipocytes and osteoblasts. Results: There was a significant decrease in cell viability and KI67 and BCL-2 expression; however, BAX was significantly upregulated in the hBM-MSCs compared to control groups. Annexin-V/PI staining results also showed the apoptotic effects of K562-MVs on hBM-MSCs. Moreover, the differentiation of hBM-MSCs into adipocytes and osteoblasts was not observed. Conclusion: MVs from the leukemic cell line could affect the viability of normal hBM-MSCs and induce cell apoptosis.

Upregulation of Pro-inflammatory Cytokine Genes by Parvovirus B19 in Human Bone Marrow Mesenchymal Stem Cells.

Chronic inflammation plays a prominent role in cancer initiation and development. On the other hand, the Inflammation can be established by a number of factors such as viral infections. Parvovirus B19 (B19V) is a pathogen with widespread infection, which infects bone marrow erythroid progenitor cells. It has been shown that B19V can also enter human bone marrow mesenchymal stem cells (BM-MSCs). In this study, we hypothesized that BM-MSCs as the main cellular component of bone marrow niche may be induced to secret pro-inflammatory cytokines after B19V infection. BM-MSCs were cultured up to passage 3. The cells were then subjected to nucleofection to transfer a plasmid containing B19V genome. After 36 h, total RNA was extracted and the expression levels of IL-1ß, IL-6, TNF-α and NF-κB genes were examined using qRT-PCR. Data analysis showed the significant increase in expression levels of all studied genes in the B19V-transfected cells (P < 0.05). Although further researches are required, our findings for the first time suggest the importance of B19V infection to establish an inflammatory microenvironment in the bone marrow and its involvement in inflammation-related diseases. Finally, based on our results, molecular assay to diagnose B19V infection of BM-MSCs prior to stem cell therapy is strongly recommended.

The effect of simultaneous administration of arsenic trioxide and microvesicles derived from human bone marrow mesenchymal stem cells on cell proliferation and apoptosis of acute myeloid leukemia cell line.

Acute Promyelocytic Leukemia is one of the most prevalent forms of leukemia which has been treated with arsenic trioxide (ATO) and/or all-trans retinoic acid (ATRA). Although, ATRA and ATO are broadly accessible and administrated, some adverse side effects have been reported recently. Nowadays, microvesicles (MVs) are considered as a potential therapeutic agent. Their capacity to alter the behavior of the cells is one of the most controversial issues. In this study, we investigated apoptotic effects of MVs derived from human bone marrow mesenchymal stem cells (hBM-MSCs) in combination with ATO on NB4 cell line. MVs were isolated by ultra-centrifugation. After 7 days, MTT assay, Annexin-V-fluorescein staining assay and RT-qPCR for BCL-2, KI67, BAX genes expression were performed. The results showed lower cell viability rate, higher apoptosis ratio, higher BAX gene, and lower KI67 and BCL-2 genes' expression in cells exposed to MVs in combination with ATO compared to cells treated with each agent alone and non-treated control. We showed that MVs in combination with ATO had more apoptotic effect on NB4 cell line than each agent alone. MVs in combination with ATO in APL treatment might play an effective therapeutic role with fewer adverse side effects compared to any other agents.