Jieping Zhang

VEGF-Mediated Proliferation of Human Adipose Tissue-Derived Stem Cells

Human adipose tissue-derived stem cells (ADSCs) are an attractive multipotent stem cell source with therapeutic applicability across diverse fields for the repair and regeneration of acute and chronically damaged tissues. In recent years, there has been increasing interest in ADSC for tissue engineering applications. However, the mechanisms underlying the regulation of ADSC proliferation are not fully understood. Here we show that 47 transcripts are up-regulated while 23 are down-regulated in ADSC compared to terminally differentiated cells based on global mRNA profiling and microRNA profiling. Among the up-regulated genes, the expression of vascular endothelial growth factor (VEGF) is fine-tuned by miR-199a-5p. Further investigation indicates that VEGF accelerates ADSC proliferation whereas the multipotency of ADSC remains stable in terms of adipogenic, chondrogenic and osteogenic potentials after VEGF treatment, suggesting that VEGF may serve as an excellent supplement for accelerating ADSC proliferation during in vitro expansion.

Role of c-Jun N-terminal kinase in the osteogenic and adipogenic differentiation of human adipose-derived mesenchymal stem cells

Although previous studies have characterized the osteogenic potential of adipose-derived mesenchymal stem cells (AMSCs) in vitro and in vivo, the molecular mechanism involved remains to be fully determined. Previously, we demonstrated that the ERK pathway plays an important role in osteogenesis and regulation of the balance between osteogenesis and adipogenesis. Here, we explored the possible role of JNKs in osteogenesis and adipogenesis of AMSCs. JNK activation in osteo-induced AMSCs was initiated at 15 min, peaked at 30 min, and declined from 45 min to basal levels. Inhibition of the JNK signaling pathway using SP600125 blocked osteogenic differentiation in a dose-dependent manner, which was revealed by an ALP activity assay, extracellular calcium deposition detection, and expression of osteogenesis-relative genes (Runx2, ALP, and OCN) via RT-PCR and real-time PCR. However, blockage of JNK did not induce a switch between osteogenesis and adipogenesis of AMSCs in the presence of dexamethasone, which is different from that of blockage of ERK. Significantly, the blockage of JNK activation in adipo-induced AMSCs by SP600125 stimulated adipogenic differentiation, which was confirmed by Oil Red O staining to detect intracellular lipid droplets, and RT-PCR and real-time PCR analysis for expression of adipogenesis-relative genes (PPARγ2 and aP2). This study suggested a potential function of the JNK pathway in committing osteogenic and adipogenic differentiation of AMSCs in vitro. However, blockage of the JNK pathway is not sufficient to induce a switch from osteogenesis to adipogenesis of AMSCs.

The usability of WeChat as a mobile and interactive medium in student‐centered medical teaching

Biochemistry and cellular biology courses for medical students at Tongji University include the assessment that provides students with feedback to enhance their learning, which is a type of formative assessment. However, frequent instant feedback and guidance for students is often absent or inconsistently included in the teaching process. WeChat, the most popular Chinese social media, was introduced in biochemistry and cellular biology course. A WeChat official account (OA) was set up as an instant interactive platform. Over a period of two semesters, OA sent 73 push notifications. The components included course notices, preclass thought questions, after‐class study materials, answer questions and feedback, simulation exercises, teacher–student interaction, and research progress relevant to the course. WeChat OA served as an active‐learning teaching tool, provided more frequent feedback and guidance to students, and facilitated better student‐centered communication in the teaching process. Using the WeChat OA in medical teaching emphasized interactive, interoperable, effective, engaging, adaptable, and more participatory teaching styles. As a new platform, WeChat OA was free, Internet‐reliant, and easily managed. Using this new medium as a communication tool accelerated further advancement of instant feedback and improvement in teaching activities. Notifications and interactive feedback via the mobile social medium WeChat OA anytime and anywhere facilitated a student‐centered teaching mode. Use of WeChat OA significantly increased the proportion of students interactively participating and resulted in a high degree of student satisfaction.

Electromagnetic analysis of tunable bandpass filters with a magnetodielectric perturber

Electromagnetic (EM) analysis is performed for a tunable bandpass filter with a magnetodielectric perturber controlled by a piezoelectric transducer. The structure includes a perturber as a superstrate which consists of thin ferrite film with a high permeability and Rogers dielectric material with a high permittivity in a sandwich style. The structure is of multiscale feature because the thickness of the thin film is very small but cannot be ignored. The problem can be solved by surface integral equations (SIEs) in the integral equation approach, but the conditioning of system matrix may not be good. We use volume-surface integral equations to formulate the problem in this work and the disadvantage of SIEs can be overcome. A numerical example is presented to illustrate the approach.

A cell culture condition that induces the mesenchymal-epithelial transition of dedifferentiated porcine retinal pigment epithelial cells

&NA; The pathological change of retinal pigment epithelial (RPE) cells is one of the main reasons for the development of age‐related macular degeneration (AMD). Thus, cultured RPE cells are a proper cell model for studying the etiology of AMD in vitro. However, such cultured RPE cells easily undergo epithelial‐mesenchymal transition (EMT) that results in changes of cellular morphology and functions of the cells. To restore and maintain the mesenchymal‐epithelial transition (MET) of the cultured RPE cells, we cultivated dedifferentiated porcine RPE (pRPE) cells and compared their behaviors in four conditions: 1) in cell culture dishes with DMEM/F12 containing FBS (CC dish‐FBS), 2) in petri dishes with DMEM/F12 containing FBS (Petri dish‐FBS), 3) in cell culture dishes with DMEM/F12 containing N2 and B27 supplements (CC dish‐N2B27), and 4) in petri dishes with DMEM/F12 containing N2 and B27 (Petri dish‐N2B27). In addition to observing the cell morphology and behavior, RPE specific markers, as well as EMT‐related genes and proteins, were examined by immunostaining, quantitative real‐time PCR and Western blotting. The results showed that dedifferentiated pRPE cells maintained EMT in CC dish‐FBS, Petri dish‐FBS and CC dish‐N2B27 groups, whereas MET was induced when the dedifferentiated pRPE cells were cultured in Petri dish‐N2B27. Such induced pRPE cells showed polygonal morphology with increased expression of RPE‐specific markers and decreased EMT‐associated markers. Similar results were observed in induced pluripotent stem cell‐derived RPE cells. Furthermore, during the re‐differentiation of those dedifferentiated pRPE cells, Petri dish‐N2B27 reduced the activity of RhoA and induced F‐actin rearrangement, which promoted the nuclear exclusion of transcriptional co‐activator with PDZ‐binding motif (TAZ) and TAZ target molecule zinc finger E‐box binding protein (ZEB1), both of which are EMT inducing factors. This study provides a simple and reliable method to reverse dedifferentiated phenotype of pRPE cells into epithelialized phenotype, which is more appropriate for studying AMD in vitro, and suggests that MET of other cell types might be induced by a similar approach.

Pseudomonas aeruginosa infection alters the macrophage phenotype switching process during wound healing in diabetic mice: P. aeruginosa regulates macrophage phenotype

Macrophages play critical roles in wound healing process. They switch from “classically activated” (M1) phenotype in the early inflammatory phase to “alternatively activated” (M2) phenotype in the later healing phase. However, the dynamic process of macrophage phenotype switching in diabetic wounds burdened with bacteria is unclear. In this report, Pseudomonas aeruginosa, frequently detected in diabetic foot ulcers, was inoculated into cutaneous wounds of db/db diabetic mice to mimic bacterium‐infected diabetic wound healing. We observed that P. aeruginosa infection impaired diabetic wound healing and quickly promoted the expression of pro‐inflammatory genes (M1 macrophage markers) tumor necrosis factor‐α (tnf‐α), interleukin‐1β (il‐1β) and il‐6 in wounds. The expression of markers of M2 macrophages, including il‐10, arginase‐1, and ym1 were also upregulated. In addition, similar gene expression patterns were observed in macrophages isolated directly from wounds. Immunostaining showed that P. aeruginosa infection increased both the ratios of M1 and M2 macrophages in wounds compared with that in control groups, which was further confirmed by in vitro culturing macrophages with P. aeruginosa and skin fibroblast conditioned medium. However, the ratios of the expression levels of pro‐inflammatory genes to anti‐inflammatory gene il‐10 was increased markedly in P. aeruginosa infected wounds and macrophages compared with that in control groups, and P. aeruginosa prolonged the presence of M1 macrophages in the wounds. These data demonstrated that P. aeruginosa in diabetic wounds activates a mixed M1/M2 macrophage phenotype with an excessive activation of M1 phenotype or relatively inadequate activation of M2 phenotype.

miR-365 promotes diabetic retinopathy through inhibiting Timp3 and increasing oxidative stress

ABSTRACT miRs play critical roles in oxidative stress‐related retinopathy pathogenesis. miR‐365 was identified in a previously constructed library from glyoxal‐treated rat Müller cell. This report explores epigenetic alterations in Müller cells under oxidative stress to develop a novel therapeutic strategy. To examine the miR‐365 expression pattern, in situ hybridization and quantitative RT‐PCR were performed. Bioinformatical analysis and dual luciferase report assay were applied to identify and confirm target genes. Streptozotocin (STZ)‐treated rats were used as the diabetic retinopathy (DR) model. Lentivirus‐mediated anti‐miR‐365 was delivered subretinally and intravitreally into the rats’ eyes. The functional and structural changes were evaluated by electroretinogram (ERG), histologically, and through examination of expression levels of metallopeptidase inhibitor 3 (Timp3), glial fibrillary acidic protein (Gfap), recoverin (Rcvrn) and vascular endothelia growth factor A (Vegfa). Oxidative stress factors and pro‐inflammatory cytokines were analyzed. miR‐365 expression was confirmed in the glyoxal‐treated rat Müller cell line (glyoxal‐treated rMC‐1). In the retina, miR‐365 mainly localized in the inner nuclear layer (INL). The increased miR‐365 participated in Müller cell gliosis through oxidative stress aggravation, as observed in glyoxal‐treated rMC‐1 and DR rats before 6 weeks. Timp3 was a target and negatively regulated by miR‐365. When miR‐365 was inhibited, Timp3 expression was upregulated, Müller cell gliosis was alleviated, and retinal oxidative stress was attenuated. Visual function was also partially rescued as detected by ERG. miR‐365 was found to be highly expressed in the retina and the abnormality of miR‐365/Timp3 pathway is closely related to the pathology, like Müller gliosis, and the visual injury in DR. The mechanism might be through oxidative stress, and miR‐365/Timp3 could be a potential therapeutic target for treating DR. HIGHLIGHTSmiR‐365 in rat retina is mainly expressed in INL, photoreceptor layer, and RPE layer.Timp3 is the direct target of and negatively regulated by miR‐365.The increased miR‐365 in Müller cells is involved in DR through miR‐365/Timp3 pathway and oxidative stress mechanism.

Design of miniaturized UHF RFID tag antenna attached to dielectric and metallic objects

In this article, a compact antenna is presented with an appropriate structure which has a good performance used on the dielectric and metallic objects. The loading bar and the meandered section are added to achieve a proper impedance matching between the antenna input terminal and the reference microchip whose impedance is 13-j143Ω. The antennas wings are utilized to improve the performance when attached to the metal surface. The size of the antenna is 50mm×20mm×1.6mm and the simple structure ensures the easy and low-cost fabrication. The simulated results show that the impedance bandwidth (return loss≤-10dB) is 100MHz (866MHz-966MHz) and 166MHz (800MHz-966MHz) when implemented on the dielectric and metallic objects, respectively.

Nyström method solution for time-domain electric field integral equations

The interaction of transient electromagnetic (EM) wave with objects can be formulated by the integral equation approach in time domain. For conducting objects or homogeneous penetrable objects, the time-domain surface integral equations (TDSIEs) can be applied. Traditionally, the TDSIEs are solved by the method of moments (MoM) in spatial domain and a march-on in time (MOT) scheme in temporal domain. In this work, we propose a hybrid scheme in which the Nyström method is used in spatial domain while the MoM with Laguerre function as a basis function in the time domain is employed. The numerical example for EM scattering by a conducting sphere is presented to demonstrate the scheme and its merits can be observed.

Electromagnetic analysis of lossy interconnects by surface integral equations

Accurate electromagnetic (EM) analysis for interconnect structures requires to consider the finite conductivity of involved conductors. The conductor loss could be accounted for through an approximate surface impedance when the skin depth of current is small. However, this approximation may not be valid for large skin depth caused by low frequencies or small conductivities. In this work, we treat the lossy conductors as homogeneous dielectric media and use electric field integral equations (EFIEs) to describe the problem. The EFIEs are solved with the method of moments (MoM) in which the Rao-Wilton-Glisson (RWG) and dual basis functions are used to represent the electric and magnetic current densities, respectively. A numerical example is presented to demonstrate the approach.