Mesenchymal stem cells as an appropriate feeder layer for prolonged in vitro culture of human induced pluripotent stem cells.

Feeder layers have been applied extensively to support the growth and stemness potential of stem cells for in vitro cultures. Mouse embryonic fibroblast and mouse fibroblast cell line (SNL) are common feeder cells for human induced pluripotent stem cells (hiPSCs) culture. Because of some problems in the use of these animal feeders and in order to simplify the therapeutic application of hiPSCs, we tested human adult bone marrow mesenchymal stem cells (hMSCs) as a potent feeder system. This method benefits from prevention of possible contamination of animal origin feeder systems. hiPSCs transferred onto mitotically inactivated hMSCs and passaged every 5 days. Prior to this culture, MSCs were characterized by flow cytometry of their surface markers and evaluation of their osteogenic and adipogenic differentiation potentials. The morphology, expressions of some specific pluripotency markers such as SSEA-3, NANOG and TRA-1-60, alkaline phosphates activity, formation embryoid bodies and their differentiation potentials of iPSCs on SNL and MSC feeder layers were evaluated. To investigate the prolonged maintenance of pluripotency, the quantitative transcriptions of some pluripotency markers including OCT4, SOX2, NANOG and REX1 were compared in the iPS clones on SNL or MSC feeders. Human iPSCs cultured on human MSCs feeder were slightly thinner and flatter than ones on the other feeder system. Interestingly MSCs supported the prolonged in vitro proliferation of hiPSCs along with maintenance of their pluripotency. Altogether our results suggest human mesenchymal stem cells as an appropriate feeder layer for human iPSCs culture for clinical applications and cell therapy.

Honey bee venom combined with 1,25-dihydroxyvitamin D3as a highly efficient inducer of differentiation in human acute myeloid leukemia cells.

PURPOSE: Most cancer cells exhibit a defect in their capacity to mature into nonreplicating adult cells and existing in a highly proliferating state. Differentiation therapy by agents such as 1,25-dihydroxyvitamin D3(1,25-(OH)2 VD3) represents a useful approach for the treatment of cancer including acute myeloid leukemia. Human myeloid leukemia cell lines are induced to terminal differentiation into monocyte lineage by 1,25-(OH)2 VD3. However, usage of these findings in the clinical trials is limited by calcemic effects of 1,25-(OH)2 VD3. Attempts to overcome this problem have focused on a combination of low concentrations 1,25-(OH)2 VD3 with other compounds to induce differentiation of HL-60 cells. In this study, the effect of honey bee venom (BV) and 1,25-(OH)2 VD3, individually and in combination, on proliferation and differentiation of human myeloid leukemia HL-60 cells were assayed. MATERIALS AND METHODS: In this in vitro study, toxic and nontoxic concentrations of BV and 1,25-(OH)2 VD3 were tested using Trypan blue stained cell counting and (3[4, 5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. In addition, differentiation of cells was assayed using a Wright-Giemsa staining and nitroblue tetrazolium reduction test. Data were analyzed by a one-way analysis of the variance test using SPSS software. RESULTS: Our findings showed that both the BV and 1,25-(OH)2 VD3, in a dose and time-dependent manner, caused cell death at high concentrations and inhibited cell proliferation at lower concentrations. About 5 nM of 1,25-(OH)2 VD3 induced differentiation of HL-60 cells to monocytes after 72 h. 2.5 µg/ml of BV suppressed proliferation of HL-60 cells but had not any effects on their differentiation, whereas in combination with 5 nM of 1,25-(OH)2 VD3, it enhanced antiproliferative and differentiation potency of 1,25-(OH)2 VD3. CONCLUSIONS: These results indicate that BV potentiates the 1,25-(OH)2 VD3-induced HL-60 cell differentiation into monocytes.