PAX4 promotes PDX1-induced differentiation of mesenchymal stem cells into insulin-secreting cells.

A shortage of postmortem pancreatic tissue for islet isolation impedes the application of cell replacement therapy in patients with diabetes. As an alternative for islet cell transplantation, transcription factors, including PDX1, PAX4, and neurogenin-3, that aid in the formation of insulin-producing ß cells during development have been investigated. The present study evaluated the effects of PAX4 and PDX1 on the differentiation of mesenchymal stem cells (MSCs) into insulin-producing ß-like cells in vitro using recombinant adenoviruses carrying PDX1 or PDX1 plus PAX4. RT-PCR, Western blot, and immunofluorescence assays were used to detect the expression levels of relevant genes and proteins, and enzyme-linked immunosorbent assays were used to determine the amount of insulin and C-peptide secreted by the virus-infected cells following stimulation with high glucose. The results showed that PAX4 markedly enhanced the propensity of PDX1-positive MSCs to form mature islet-like clusters and functional insulin-producing ß-like cells. Our findings provide a novel foundation for generating ß-like cells from MSCs with PAX4 and PDX1 for future clinical application.

In vitro labeling of endothelial progenitor cells isolated from peripheral blood with superparamagnetic iron oxide nanoparticles.

The transplantation of endothelial progenitor cells (EPCs) provides a novel method for the treatment of human tumors or vascular diseases. Magnetic resonance imaging (MRI) has proven to be effective in tracking transplanted stem cells by labeling the cells with superparamagnetic iron oxide (SPIO) nanoparticles. The SPIO has been used to label and track the EPCs; however, the effect of SPIO upon EPCs remains unclear on a cellular level. In the present study, EPCs were labeled with home-synthesized SPIO nanoparticles in vitro and the biological characteristics of the labeled EPCs were evaluated. The EPCs were isolated from the peripheral blood of New Zealand rabbits and cultured in fibronectin-coated culture flasks. The EPCs were labeled with home-synthesized SPIO nanoparticles at a final iron concentration of 20 µg/ml. Labeled EPCs were confirmed with transmission electron microscopy and Prussian blue staining. The quantity of iron/cell was detected by atomic absorption spectrometry. The membranous antigens of EPCs were detected by cytofluorimetric analysis. Cell viability and proliferative capability between the labeled and unlabeled EPCs were compared. The rabbit EPCs were effectively labeled and the labeling efficiency was approximately 95%. The SPIO nanoparticles were localized in the endosomal vesicles of the EPCs, which were confirmed by transmission electron microscopy. No significant differences were found in cell viability and proliferative capability between labeled and unlabeled EPCs (P>0.05). In conclusion, rabbit peripheral blood EPCs were effectively labeled by home-synthesized SPIO nanoparticles, without influencing their main biological characteristics.

Assessment of biological characteristics of mesenchymal stem cells labeled with superparamagnetic iron oxide particles in vitro.

Mesenchymal stem cell (MSC) transplantation provides a novel strategy for the treatment of human disease. MR imaging (MRI) is able to track transplanted stem cells labeled with superparamagnetic iron oxide (SPIO) in vivo. However, the effect of SPIO upon labeled MSCs remains unclear on a cellular level. In this study, the biological characteristics of rat MSCs labeled with home-synthesized SPIO particles were evaluated. The MSCs were isolated from the bone marrow of 5 adult Sprague-Dawley rats and labeled with home-synthesized SPIO particles at a final iron concentration of 20 µg/ml. Labeled MSCs were confirmed with Prussian blue staining and transmission electron microscopy. The quantity of iron per cell was determined by atomic absorption spectrometry. Cell viability, proliferation, membranous antigen and multiple differentiation ability were compared between labeled and unlabeled MSCs. The rat MSCs were effectively labeled and the labeling efficiency was approximately 100%, as revealed by Prussian blue staining. The SPIO particles located in the endosomal vesicles of the MSCs were confirmed by transmission electron microscopy. No significant differences were observed in cell viability, proliferation, membranous antigen and multiple differentiation ability between the labeled and unlabeled MSCs (P>0.05). In conclusion, MSCs are able to be effectively labeled by home-synthesized SPIO particles without influencing their main biological characteristics.