PEI-Fe3O4 Nanoparticles for Human Amniotic Epithelial Cells Labeling

Objective To label human amniotic epithelial cells(hAECs) by using PEI-Fe₃O₄ nanoparticles. Methods The PEI-Fe₃O₄ nanoparticles were characterized by using transmission electron microscopy and dynamic light scattering. The primary cultured hAECs were labeled with the nanoparticles,and the labeling efficiency was evaluated by Prussian blue staining. The cell survival rate and viability were tested by using placenta blue staining and CCK-8 assay,respectively. Results The PEI-Fe₃O₄ nanoparticles were compact spheres with an average particle size of 13 nm,a hydrodynamic radius of 17.56 nm,and a zeta potential of+34.5 mV. The labeling efficiency of the nanoparticles on hAECs reached 91% when the concentrations were greater than 20 μg/ml. When the concentrations of nanoparticles were at 50 μg/ml(t=16.37,P<0.0001;t=10.39,P<0.0001) and 100 μg/ml(t=29.89,P<0.0001;t=16.86,P<0.0001),the cell survival rates and cell viabilities were significantly reduced versus controls. Conclusion The PEI-Fe₃O₄ nanoparticles can be used for labeling hAECs without obvious cytotoxicity at its working concentration.

Repression of COUP-TFI Improves Bone Marrow-Derived Mesenchymal Stem Cell Differentiation into Insulin-Producing Cells

Identifying molecular mechanisms that regulate insulin expression in bone marrow-derived mesenchymal stem cells (bmMSCs) can provide clues on how to stimulate the differentiation of bmMSCs into insulin-producing cells (IPCs), which can be used as a therapeutic approach against type 1 diabetes (T1D). As repression factors may inhibit differentiation, the efficiency of this process is insufficient for cell transplantation. In this study, we used the mouse insulin 2 (Ins2) promoter sequence and performed a DNA affinity precipitation assay combined with liquid chromatography-mass spectrometry to identify the transcription factor, chicken ovalbumin upstream promoter transcriptional factor I (COUP-TFI). Functionally, bmMSCs were reprogrammed into IPCs via COUP-TFI suppression and MafA overexpression. The differentiated cells expressed higher levels of genes specific for islet endocrine cells, and they released C-peptide and insulin in response to glucose stimulation. Transplantation of IPCs into streptozotocin-induced diabetic mice caused a reduction in hyperglycemia. Mechanistically, COUP-TFI bound to the DR1 (direct repeats with 1 spacer) element in the Ins2 promoter, thereby negatively regulating promoter activity. Taken together, the data provide a novel mechanism by which COUP-TFI acts as a negative regulator in the Ins2 promoter. The differentiation of bmMSCs into IPCs could be improved by knockdown of COUP-TFI, which may provide a novel stem cell-based therapy for T1D.

In vitro reprogramming of rat bone marrow-derived mesenchymal stem cells into insulin-producing cells by genetically manipulating negative and positive regulators

Islet cell replacement therapy represents the most promising approach for the cure of type 1 diabetes if autoimmunity to β cells is under control. However, this potential is limited by a shortage of pancreas donors. To address the donor shortage problem, we determined whether bone marrow-derived mesenchymal stem cells (bmMSCs) can be directly reprogrammed to islet lineages by simultaneously forced suppression and over-expression of key regulator genes that play critical roles during pancreas development. Here, we report that rat bmMSCs were converted in vitro into insulin-producing cells by suppressing two-repressor genes repressor element-1 silencing transcription factor/neuronal restrictive silencing factor (Rest/Nrsf) and sonic hedgehog (Shh) and by over-expressing pancreas and duodenal transcription factor 1 (Pdx1). The reprogrammed bmMSCs expressed both genes and proteins specific for islet cells. These converted cells were capable of releasing insulin in a glucose-responsive manner. Our study suggests that bmMSCs may ultimately be reprogrammed to functional insulin-secreting cells.

[Effect of epidermal growth factor on migration of human amniotic mesenchymal stem cells]

OBJECTIVE

To explore the mechanism via which the epidermal growth factor (EGF) affects the migration of human amnion-derived mesenchymal stem cells (hAMSCs).

METHODS

In vitro cultured hAMSCs were divided into control (untreated), EGF group, inhibitor AG1478 + EGF group, inhibitor LY294002 + EGF group, and inhibitor U0126 + EGF group. The migration ability of hAMSCs in each group was measured using Transwell chamber. The expressions of phosphorylated EGFR (P-EGFR), phosphorylated AKT (P-AKT), and phosphorylated ERK1/2 (P-ERK1/2) as well as the expressions of metalloproteinase (MMP) -2 and MMP-9 were detected using Western blot analysis. The differentially expressed genes in the culture solutions in EGF groups and control group were analyzed with RNA-Seq technique.

RESULTS

Cells in EGF group had significantly stronger migration ability than in control group (P = 0.0361), inhibitor AG1478 + EGF group (P = 0.0113), inhibitor LY294002 + EGF group (P = 0.0169), and inhibitor U0126 + EGF group (P = 0.0293). EGF increased the phosphorylation levels of EGFR, AKT and ERK, and increased the expression of MMP-2. However, the increased expressions of P-AKT and P-ERK could be suppressed by AG1478 and LY294002. As shown by GO functional enrichment analysis and KEGG pathway analysis, EGF increased the transcription of genes, which were mainly involved in transcriptional regulation, protein modification, and apoptosis inhibition. Genes that were involved in the MARK pathway included DUSP5, IL1B, DUSP6, NGF, and HSPA2.

CONCLUSION

EGF-induced migration of hAMSCs may be mediated by the signaling pathways of PI3K and ERK, which needs MMP-2 expression and the co-expression of genes involved in transcriptional regulation, protein modification, and apoptosis inhibition.

[Effect of the human amniotic membrane loaded with human amniotic mesenchymal stem cells on the skin wounds of SD rats]

OBJECTIVE

To observe the effect of the human amniotic membrane (HAM) loaded with human amniotic mesenchymal stem cells (hAMSCs) on the skin wounds of SD rats.

METHODS

The amniotic epithelial cells were removed by trypsin digestion, hAMSCs were loaded onto HAM and then covered on rats' skin defects. The wound healing was observed by HE staining and immunohistochemistry, and the results were compared with the amniotic membrane group and blank control group.

RESULTS

The average wound healing time was (18.3 +/- 0.9) d in the HAM load with hAMSCs group, which was significantly faster than those in the blank control group [(26.4 +/- 0.7) d, P < 0.01] and the amniotic membrane group [(21.5 +/- 1.2) d, P < 0.05]. After 11 d and 14 d, the wound healing rates in the HAM load with hAMSCs group were (81.5 +/- 7.2)% and (94.3 +/- 3.6)%, respectively, which were significantly higher than those in the blank control group [(48.5 +/- 3.2)% and (74.3 +/- 4.3 )%] and the amniotic membrane group [(68.5 +/- 4.5)% and (86.8 +/- 4.8)%] (all P < 0.01). Skin biopsy/HE staining confirmed that the quality of wound healing in the HAM load with hAMSCs group was significantly better than in the amniotic membrane group and the blank control group. Immunohistochemical staining showed that the number of CK19-positive epidermal stem cells in the HAM load with hAMSCs group (48.2 +/- 3.2) was significantly larger than those in the amniotic membrane group (37.7 +/- 3.1) (P < 0.05) and the blank control group (29.6 +/- 2.4) (P < 0.01). Furthermore, the vascular endothelial growth factor expression (64.5 +/- 4.5) in the HAM load with hAMSCs group was also significantly higher than those in the amniotic membrane group (52.6 +/- 3.8) (P < 0.05) and the blank control group (40.7 +/- 3.1) (P < 0.01).

CONCLUSION

HAM loaded with hAMSCs may promote the repair of skin wounds by promoting the regeneration of epidermal stem cells and capillaries.

[Cell reprogramming: control key genes to obtain needed cells]

Cell reprogramming is a progress in which the memory of a mature cell is erased and then the cell develops novel phenotype and function; ultimately, the fate of the cell changes. Cell reprogramming usually occurs at genes expression levels that no genomic DNA sequence change will be involved. By changing the programs of the genetic expressions of cells in terms of space and time, cell reprogramming alters the differentiation of cells and thus produces the required cells. Further research on cells reprogramming will elucidate the mechanisms that govern the cell development, and thus provides more information of the sources of seed cells used for regeneration medicine. More cells differentiated from many terminally differentiated cells will be obtained, which is extremely important for the understanding of molecular differentiation and for the development of cell replacement therapy. This article summarizes the classification, influencing factors, approaches and latest advances of cells reprogramming.