Micro-vesicles from mesenchymal stem cells over-expressing miR-34a inhibit transforming growth factor-β1-induced epithelial-mesenchymal transition in renal tubular epithelial cells in vitro

Background:The use of microRNAs in the therapy of kidney disease is hampered by the difficulties in their effective delivery.Microvesicles(MVs)are known as natural carriers of small RNAs.Our prior research has demonstrated that MVs isolated from mesenchymal stem cells(MSCs)are capable of attenuating kidney injuries induced by unilateral ureteral obstruction and 5/6 sub-total nephrectomy in mice.The present study aimed to evaluate the effects of miR-34a-5p(miR-34a)-modified MSC-MVs on transforming growth factor(TGF)-β1-induced fibrosis and apoptosis in vitro.Methods:Bone marrow MSCs were modified by lentiviruses over-expressing miR-34a,from which MVs were collected for the treatment of human Kidney-2(HK-2)renal tubular cells exposed to TGF-β1(6 ng/mL).The survival of HK-2 cells was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide(MTT)and Annexin V-Light 650/propidium iodide(PI)assays.The expression levels of epithelial markers(tight junction protein 1[TJP1]and E-cadherin)and mesenchymal markers(smooth muscle actin alpha(α-SMA)and fibronectin)in HK-2 cells were measured using Western blot analysis and an immunofluorescence assay.In addition,changes in Notch-1/Jagged-1 signaling were analyzed using Western blotting.Data were analyzed using a Student’s t test or one-way analysis of variance.Results:MiR-34a expression increased three-fold in MVs generated by miR-34a-modified MSCs compared with that expressed in control MVs(P<0.01,t=16.55).In HK-2 cells,TJP1 and E-cadherin levels decreased to 31%and 37%after treatment with TGF-β1,respectively,and were restored to 62%and 70%by miR-34a-enriched MSC-MVs,respectively.The expression ofα-SMA and fibronectin increased by 3.9-and 5.0-fold following TGF-β1 treatment,and decreased to 2.0-and 1.7-fold after treatment of HK-2 cells with miR-34a-enriched MSC-MVs.The effects of miR-34a-enriched MSC-MVs on epithelial-mesenchymal transition(EMT)markers were stronger than control MSC-MVs.The effects of miR-34a-enriched MSC-MVs on these EMT markers were stronger than control MSC-MVs.Notch-1 receptor and Jagged-1 ligand,two major molecules of Notch signaling pathway,are predicted targets of miR-34a.It was further observed that elevation of Notch-1 and Jagged-1 induced by TGF-β1 was inhibited by miR-34a-enriched MSC-MVs.In addition,TGF-β1 exposure also induced apoptosis in HK-2 cells.Although miR-34a-mofidied MSC-MVs were able to inhibit TGF-β1-triggered apoptosis in HK-2 cells,the effects were less significant than control MSC-MVs(control:TGF-β1:miR-nc-MV:miR-34a-MV=1.3:0.6:1.1:0.9 for MTT assay,1.8%:23.3%:9.4%:17.4%for apoptosis assay).This phenomenon may be the result of the pro-apoptotic effects of miR-34a.Conclusions:The present study demonstrated that miR-34a-over-expressing MSC-MVs inhibit EMT induced by pro-fibrotic TGF-β1 in renal tubular epithelial cells,possibly through inhibition of the Jagged-1/Notch-1 pathway.Genetic modification of MSC-MVs with an anti-fibrotic molecule may represent a novel strategy for the treatment of renal injuries.

Corrosion Resistance and Durability of Superhydrophobic Coating on AZ31 Mg Alloy via One-Step Electrodeposition

To enhance durability and adhesion of superhydrophobic surface,an integrated superhydrophobic calcium myristate(Ca[CH3(CH2)12COO]2)coating with excellent corrosion resistance was fabricated on AZ31 magnesium(Mg)alloy via one-step electrodeposition process.Field-emission scanning electron microscopy,Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy as well as X-ray diff raction were employed to investigate the surface characteristics(morphology,composition and structure)of the coatings.Hydrophobicity of the coating was evaluated by means of contact and sliding angles.Additionally,potentiodynamic polarization,electrochemical impedance spectroscopy and hydrogen evolution tests were conducted to characterize the corrosion resistance.Results indicated that the coating exhibited super-hydrophobicity with large static water contact angle(CA)and small sliding angle of 155.2°±1.5°and 6.0°±0.5°,respectively,owing to spherical rough structure and low surface energy(7.01 mJ m^(-2)).The average hydrogen evolution rate(HERa)and corrosion current density(icorr)of the coated sample were 5.3μL cm^(-2)h^(-1) and 5.60×10^(-9)A cm^(-2),about one and four orders of magnitude lower than that of AZ31 substrate,respectively,implying the excellent corrosion resistance.The CA of the coating remained 155.6°±0.9°after soaking for 13 days,showing the super-hydrophobicity and stability of the coating.Simultaneously,the large critical load(5004 mN)for the coating designated the outstanding adhesion to the substrate by nano-scratch test.

Miscibility and Isothermal Crystallization of Poly(L-lactide) and Poly(trimethylene carbonate) Blends

Miscibility, isothermal crystallization kinetics, and morphology of poly（L-lactide）/poly（trimethylene carbonate） （PLLA/PTMC） crystalline/amorphous blends were studied by differential scanning calorimetry （DSC） and optical microscopy （OM）. The heterogeneity of OM images and an unchanged glass transition temperature showed that PLLA was immiscible with PTMC. During isothermal crystallization, the crystallization rate of PLLA improved when the PTMC content was low （≤ 20%）. However, when the PTMC content was high （≥ 30%）, the crystallization rate decreased significantly. The reason of these nonlinear changes in crystal kinetics was analyzed according to the nucleation and growth process by virtue of a microscope heating stage. The isothermal crystallization morphologies of the blends were also studied by polarized optical microscopy and the results confirmed the conclusions obtained from crystallization kinetics.

Effects of Functionalized Graphenes on the Isothermal Crystallization of Poly(L-lactide) Nanocomposites

The effects of graphene oxide（GO） with polar groups and functionalized GO（f GO） with nonpolar groups on the isothermal crystallization of poly（L-lactide）（PLLA） were compared. Functionalized GO was obtained by grafting octadecylamine and characterized by FTIR, WAXD and TGA. Isothermal crystallization kinetics of PLLA/GO and PLLA/f GO nanocomposites were investigated by combining DSC data and Avrami equation. The results showed that f GO could improve PLLA crystallization rate more obviously than GO. By analyzing the morphology obtained from POM, SEM and TEM, it was found f GO with large layer space dispersed better in PLLA and supplied more nucleation sites than GO. Therefore, for the multilayer graphene, increasing the layer spaces is important to improve its dispersion in polymers, which will cause the crystal kinetics changing of polymers.