Evaluation of genetic response of mesenchymal stem cells to nanosecond pulsed electric fields by whole transcriptome sequencing

BACKGROUND Mesenchymal stem cells(MSCs)modulated by various exogenous signals have been applied extensively in regenerative medicine research.Notably,nanosecond pulsed electric fields(nsPEFs),characterized by short duration and high strength,significantly influence cell phenotypes and regulate MSCs differentiation via multiple pathways.Consequently,we used transcriptomics to study changes in messenger RNA(mRNA),long noncoding RNA(lncRNA),microRNA(miRNA),and circular RNA expression during nsPEFs application.AIM To explore gene expression profiles and potential transcriptional regulatory mechanisms in MSCs pretreated with nsPEFs.METHODS The impact of nsPEFs on the MSCs transcriptome was investigated through whole transcriptome sequencing.MSCs were pretreated with 5-pulse nsPEFs(100 ns at 10 kV/cm,1 Hz),followed by total RNA isolation.Each transcript was normalized by fragments per kilobase per million.Fold change and difference significance were applied to screen the differentially expressed genes(DEGs).Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed to elucidate gene functions,complemented by quantitative polymerase chain reaction verification.RESULTS In total,263 DEGs were discovered,with 92 upregulated and 171 downregulated.DEGs were predominantly enriched in epithelial cell proliferation,osteoblast differentiation,mesenchymal cell differentiation,nuclear division,and wound healing.Regarding cellular components,DEGs are primarily involved in condensed chromosome,chromosomal region,actin cytoskeleton,and kinetochore.From aspect of molecular functions,DEGs are mainly involved in glycosaminoglycan binding,integrin binding,nuclear steroid receptor activity,cytoskeletal motor activity,and steroid binding.Quantitative real-time polymerase chain reaction confirmed targeted transcript regulation.CONCLUSION Our systematic investigation of the wide-ranging transcriptional pattern modulated by nsPEFs revealed the differential expression of 263 mRNAs,2 miRNAs,and 65 lncRNAs.Our study demonstrates that nsPEFs may affect stem cells through several signaling pathways,which are involved in vesicular transport,calcium ion transport,cytoskeleton,and cell differentiation.

Application of a Pulsed Electric Field to Modify the Free Energy of the Active Site of an Azoreductase

The Gibbs free energy is strongly related to the stability and catalytic function of an enzyme through the energetic changes that occur in the chemical reactions the enzyme catalyzes. In this in silico study, a pulsed electric field was applied to an azoreductase, and its effect on the Gibbs free energy of molecular docking with two dyes was measured. We propose that certain stimuli from a pulsed electric field favor the structural stability of the enzyme by promoting an arrangement in the active site, potentially leading to an enhancement of enzymatic activity overall.

The influence of pore characteristics on rock fragmentation mechanism by high-voltage electric pulse

High-voltage electric pulse(HVEP)is an innovative low-energy and high-efficiency technique.However,the underlying physics of the electrical breakdown within the rock,and the coupling mechanism between the various physical fields involved in HVEP still need to be further understood.In this study,we establish a 2D numerical model of multi-physical field coupling of the electrical breakdown of porous rock with randomly distributed pores to investigate the effect of pore characteristics(porosity,pore media composition)on the partial electrical breakdown of rock(i.e.the generation of a plasma channel inside the rock).Our findings indicate that the generation of a plasma channel is directionally selective and extends in the direction of a weak electrical breakdown intensity.As the porosity of the rock increases,so does the intensity of the electric field in the‘electrical damage’region—the greater the porosity,the greater the effectiveness of rock-breaking.As the fraction of pore fluid(S_(water)/S_(air))gradually declines,the generation time of the plasma channel decreases,and the efficacy of rock-breaking by HVEP increases.In addition,in this study,we conducted an indoor experiment utilizing an electric pulse drill to break down the rock in order to recreate the growth mode of the plasma channel in the rock.Moreover,the experimental results are consistent with the simulation results.In addition,the development of this type of partial electrical breakdown is confirmed to be related to electrode polarity and pore characteristics via the experiment of the symmetrical needle-needle electrode arrangement,which further demonstrates the mechanism of partial electrical breakdown.This research is significant for comprehending the process of electric impulse rock-breaking and gives theoretical guidance and technological support for advancing electric impulse drilling technology.

Demulsification Behavior, Characteristics, and Performance of Surfactant Stabilized Oil-in-Water Emulsion under Bidirectional Pulsed Electric Field

As a novel electric demulsification method,bidirectional pulsed electric field(BPEF)was employed to demulsify the surfactant stabilized oil-in-water(SSO/W)emulsion for oil/water separation in this work.The demulsification behavior,characteristics,and stages under BPEF were explored.It was discovered that BPEF drove SSO/W emulsion to move and form vortexes,during which the oil droplets aggregated and accumulated to generate an oil droplet layer(ODL).ODL subsequently transformed into a continuous oil layer(COL)leading to the demulsification and separation of SSO/W emulsion.The conversion rate of ODL to COL was defined and used to evaluate the demulsification process and reflect the coalescence ability and transformation efficiency of dispersed oil droplets into COL.Furthermore,the effects of BPEF voltage,frequency,duty cycle,ratio of pulse output time,and surfactant type and content on the demulsification performance were examined.The optimal values of BPEF parameters for demulsification operation were 400 V,25 Hz,50%,and 4:1.O/W emulsion containing anionic surfactant was apt to be demulsified by BPEF,nonionic surfactant took the second place and cationic surfactant was the most difficult.A high surfactant content was not conducive to the BPEF demulsification.This work is anticipated to provide useful guidance for oil/water separation and oil recovery from actual emulsified oily wastewater by BPEF.

Recent progress in pulsed electric field ablation for liver cancer

The number of liver cancer patients is likely to continue to increase in the coming decades due to the aging of the population and changing risk factors.Traditional treatments cannot meet the needs of all patients.New treatment methods evolved from pulsed electric field ablation are expected to lead to breakthroughs in the treatment of liver cancer.This paper reviews the safety and efficacy of irreversible electroporation in clinical studies,the methods to detect and evaluate its ablation effect,the improvements in equipment and its antitumor effect,and animal and clinical trials on electrochemotherapy.We also summarize studies on the most novel nanosecond pulsed electric field ablation techniques in vitro and in vivo.These research results are certain to promote the progress of pulsed electric field in the treatment of liver cancer.

Tumor ablation with nanosecond pulsed electric fields

Liver cancer is one of the most malignant cancers. It is reported that 600 000 patients died from liver cancer every year. [1,2] Hepatocellular carcinoma (HCC) is a particular problem because symptoms are not evident until the disease has progressed and hepatitis B, which is prominent specific regions of Asia, is a common precursor of the disease. There are many liver

Effect of low-frequency pulse percutaneous electric stimulation on peripheral nerve injuries at different sites

BACKGROUND: The postoperative recovery of nerve function in patients with peripheral nerve injury is always an important problem to solve after treatment. The electric stimulation induced electromagnetic field can nourish nerve, postpone muscular atrophy, and help the postoperative neuromuscular function. OBJECTIVE: To observe the effects of low-frequency pulse percutaneous electric stimulation on the functional recovery of postoperative patients with peripheral nerve injury, and quantitatively evaluate the results of electromyogram (EMG) examination before and after treatment. DESIGN: A retrospective case analysis. SETTING: The Sixth People’s Hospital affiliated to Shanghai Jiaotong University. PARTICIPANTS: Nineteen postoperative inpatients with peripheral nerve injury were selected from the Department of Orthopaedics, the Sixth People’s Hospital affiliated to Shanghai Jiaotong University from June 2005 to January 2006, including 13 males and 6 females aged 24-62 years with an average of 36 years old. There were 3 cases of brachial plexus nerve injury, 3 of median nerve injury, 7 of radial nerve injury, 3 of ulnar nerve injury and 3 of common peroneal nerve injury, and all the patients received probing nerve fiber restoration. Their main preoperative manifestations were dennervation, pain in limbs, motor and sensory disturbances. All the 19 patients were informed with the therapeutic program and items for evaluation. METHODS: ① Low-frequency pulse percutaneous electric stimulation apparatus: The patients were given electric stimulation with the TERESA cantata instrument (TERESA-0, Shanghai Teresa Health Technology, Co.,Ltd.). The patients were stimulated with symmetric square waves of 1-111 Hz, and the intensity was 1.2-5.0 mA, and it was gradually adjusted according to the recovered conditions of neural regeneration following the principle that the intensity was strong enough and the patients felt no obvious upset. They were treated for 4-24 weeks, 10-30 minutes for each time, 1-3 times a day, and 6 weeks as a course. ② EMG examination was applied to evaluate the recoveries of recruitment, motor conduction velocity (MCV) and sensory conduction velocity (SCV) before and after treatment. The patients were examined with the EMG apparatus (DISA2000C, Danmark) before and after the treatment of percutaneous electric stimulation. ③ Standards for evaluating the effects included cured (complete recovery of motor functions, muscle strength of grade 5, no abnormality in EMG examination), obviously effective [general recovery of motor function, muscle strength of grade 4, no or a few denervation potentials, motor conduction velocity (MCV) and sensory conduction velocity (SCV)], improved (partial recovery of motor function, muscle strength of grade 3, denervation potentials and reinneration potentials, slowed MCV and SCV, invalid (no obvious changes of motor function). MAIN OUTCOME MEASURES: ① Ameliorated degree of the nerve function of the postoperative patients with peripheral nerve injury treated with percutaneous electric stimulation; ② Changes of EMG examination before and after treatment. RESULTS: All the 19 postoperative patients with peripheral nerve injury were involved in the analysis of results. ① Comparison of nerve function before and after treatment in 19 patients with peripheral nerve injury of different sites: For the patients with radial nerve injury (n=7), the nerve functions all completely recovered after 8-week treatment, and the cured and obvious rate was 100% (7/7); For the patients with brachial plexus nerve injury (n=3), 1 case had no obvious improvement, and the cured and obvious rate was 67% (2/3); For the patients with common peroneal nerve injury (n=3), the extension of foot dorsum generally recovered in 1 case of nerve contusion after 4-week treatment, and the cured and obvious rate was 67% (2/3); For the patients with median nerve injury (n=3), muscle strength was obviously recovered, and the cured and obvious rate was 100% (3/3); For the patients with ulnar nerve injury (n=3), 1 case only had recovery of partial senses, and the cured and obvious rate was 67% (2/3). Totally 9 cases were cured, 7 were obviously effective, 1 was improved, and only 2 were invalid. After 4 courses, the cured rate of damaged nerve function after four courses was 47% (9/19), and effective rate was 89% (17/19). ② Comparison of EMG examination before and after treatment: Before and after percutaneous electric stimulation, he effective rates of recruitment, MCV and SCV were 89% (17/19), 58% (11/19), 47% (9/19) respectively, and there were extremely obvious differences (P < 0.01). CONCLUSION: ① Low-frequency pulse percutaneous electric stimulation can improve the nerve function of postoperative patients with peripheral nerve injury of different sites, especially that the injuries of radial nerve and median nerve recover more obviously. ②Percutaneous electric stimulation can ameliorate the indexes of EMG examination, especially the recruitment, in postoperative patients with peripheral nerve injury.

Evolution of melt convection in a liquid metal driven by a pulsed electric current

Gain refinement in metal alloy can be achieved by applying an electric current pulse(ECP)in solidification process.Forced flow inside the melt has been proved to be a key role in grain refinement.In this paper,the fluid flow inside Ga 20 wt%-In 12 wt%-Sn alloy induced by a damping sinusoidal ECP flowing through two parallel electrodes into the cylindrical melt was investigated by both experimental measurements and numerical simulations.Experimental results showed that a strong descending jet was induced beneath the bottom of electrodes under the application of ECP.Besides,it was found that flow intensity increases with the increase of amplitude,frequency,and pulse width,respectively.In order to unlock the formation mechanism of flow pattern and the relevance of flow intensity varied with electrical parameters,a three-dimensional numerical model under the application of ECP was established.Meanwhile,a comparative study was conducted by numerical simulations to reveal the distributions of electromagnetic fields and forced flow.Numerical results showed that the downward Lorentz force induced by ECP was concentrated beneath the bottom of electrodes.This downward Lorentz force induces a descending jet and provokes a global forced flow.According to numerical simulations,the evolution of flow intensity with electrical parameters under the application of ECP can be understood by the time averaged impulse of Lorentz force.

Treatment time influences the effects of a low-frequency pulsed electric field on synthesis of tyrosine hydroxylase and dopamine in PC12 cells

BACKGROUND:Electromagnetic radiation can influence dopamine(DA) synthesis in brain tissues or cells,but electromagnetic frequencies,intensities,and radiation time can produce different effects.In addition,the signal pathway by which electromagnetic radiation influences DA synthesis remains controversial.OBJECTIVE:To determine tyrosine hydroxylase(TH) expression in PC12 cells and DA levels in cell culture media after different periods of low-frequency pulsed electric field(LF-PEF) stimulation,and to determine how LF-PEF signaling stimulates TH synthesis using inhibitors.DESIGN,TIME AND SETTING:A parallel,controlled,cell experiment was performed at the Laboratory of Cell Biology,School of Life Science,East China Normal University,between January and October 2006.MATERIALS:PC12 cells were purchased from the Shanghai Institute of Biochemistry and Cell Biology,Chinese Academy of Sciences,China.Nerve growth factor was purchased from PeproTech,USA.The protein kinase A inhibitor,H-89,and mitogen-activated protein kinase kinase inhibitor,U0126,were purchased from Sigma,USA.METHODS:(1) Following routine culture in Dulbecco's modified eagle medium,primary PC12 cells were stimulated under LF-PEF(pulse frequency 50 Hz,pulse width 20 μs,peak field strength 1 V/m) for 5,10,15,20,and 30 minutes.(2) Inhibitors(H-89 or U0126,1 μmol/L) were added 30 minutes before LF-PEF stimulation for 10 minutes.MAIN OUTCOME MEASURES:(1) TH expression was determined by Western blot in PC12 cells at 0.5,1,2,3,and 4 days after LF-PEF stimulation.Similarly,DA was measured by high-performance liquid chromatography in media at 2,3,4,or 5 days after LF-PEF.(2) TH expression was detected 1 day after H-89 or U0126 treatment and LF-PEF.RESULTS:(1) Short-term LF-PEF stimulation(5 and 10 minutes) increased TH expression and media DA levels after short-term culture(2 days)(P<0.01),but both parameters decreased with longer culture(3-4 days)(P<0.01).Long-term LF-PEF stimulation(15,20,or 30 minutes) decreased TH and DA synthesis,followed by a rapid increase(P<0.01).(2) H89 could completely inhibit TH expression in PC12 cells stimulated by LF-PEF for 10 minutes,while the inhibition rate of U0126 was 53.2%.CONCLUSION:Short-term LF-PEF first promotes then inhibits,while long-term LF-PEF first inhibits then promotes,TH and DA synthesis.LF-PEF stimulation regulates TH expression primarily by activating protein kinase A to regulate DA synthesis.

A Pulsed Electromagnet for Laser Wakefield Electron Acceleration Experiments

Laser Wakefield plasma acceleration of electrons to energies above 10 GeV, may be possible in the new high power Laser beam facilities. The design of an Electron Spectrometer with an electro-magnet with adjustable magnetic field is proposed for the characterization of electron energy spectrum with a precision better than 10% for the entire energy range from 0.5 GeV to 38 GeV. The expected precision in the measurement of the electron energy is calculated as a function of the magnetic field, of the electron energy and of the magnet length. To outline the advantages offered by a pulsed electromagnet with high magnetic fields, the mass and the electric power lost in the coils of a 4 m long electromagnet with continuous current and Iron yoke are calculated.

Effect of electric pulse rolling on plastic forming ability of AZ91D magnesium alloy

AZ91D magnesium alloy rolled under four rolling conditions,namely cold rolling,electric pulsecold rolling,hot rolling and electric pulse hot rolling,and the first principles calculation of Mg with or without external electric field carried out.The results show that:The application of pulse current in the rolling process of AZ91D magnesium alloy can effectively improve the edge crack of the sample,optimize the texture of AZ91D magnesium alloy and reduce its texture strength,promote the generation of tensile twins and the transition from small Angle grain boundaries to large Angle grain boundaries,and thus improve the plastic forming ability of AZ91D magnesium alloy.Make it more prone to plastic deformation.Compared with ordinary rolling,the microhardness ofα-Mg matrix decreases by 15%.The tensile strength and elongation increased from 137MPa and 3.4%to 169MPa and 4.7%,respectively.The results show that the stiffness of Mg decreases and the Poisson's ratio of Mg increases when the electric field applies.When the B/G value is greater than 1.75,the plasticity of Mg is improved.The fault energy at the base surface of Mg does not change much,while the fault energy at the prismatic surface of Mg decreases obviously,showing the external electric field mainly affects the prismatic surface slip of Mg,which makes the prismatic surface slip easier to start,and thus improves the plastic forming ability of Mg.

The latest research progress on minimally invasive treatments for hepatocellular carcinoma

Background:Hepatocellular carcinoma(HCC)is the fourth leading cause of cancer-related death worldwide.Due to the high prevalence of hepatitis B virus(HBV)infection in China,the incidence of HCC in China is high,and liver cirrhosis caused by chronic hepatitis also brings great challenges to treatment.This paper reviewed the latest research progress on minimally invasive treatments for HCC,including percutaneous thermal ablation and new nonthermal ablation techniques,and introduced the principles,advantages,and clinical applications of various therapeutic methods in detail.Data sources:The data of treatments for HCC were systematically collected from the Pub Med,Science Direct,American Chemical Society and Web of Science databases published in English,using“minimally invasive”and“hepatocellular carcinoma”or“liver cancer”as the keywords.Results:Percutaneous thermal ablation is still a first-line strategy for the minimally invasive treatment of HCC.The effect of microwave ablation(MWA)on downgrading treatment before liver transplantation is better than that of radiofrequency ablation(RFA),while RFA is more widely used in the clinical practice.High-intensity focused ultrasound(HIFU)is mainly used for the palliative treatment of advanced liver cancer.Electrochemotherapy(ECT)delivers chemotherapeutic drugs to the target cells while reducing the blood supply around HCC.Irreversible electroporation(IRE)uses a microsecond-pulsed electric field that induces apoptosis and necrosis and triggers a systemic immune response.The nanosecond pulsed electric field(ns PEF)has achieved a good response in the ablation of mice with HCC,but it has not been reported in China for the treatment of human HCC.Conclusions:A variety of minimally invasive treatments provide a sufficient survival advantage for HCC patients.Nonthermal ablation will lead to a new wave with its unique advantage of antitumor recurrence and metastasis.

Memristive Artificial Synapses for Neuromorphic Computing

Neuromorphic computing simulates the operation of biological brain function for information processing and can potentially solve the bottleneck of the von Neumann architecture.This computing is realized based on memristive hardware neural networks in which synaptic devices that mimic biological synapses of the brain are the primary units.Mimicking synaptic functions with these devices is critical in neuromorphic systems.In the last decade,electrical and optical signals have been incorporated into the synaptic devices and promoted the simulation of various synaptic functions.In this review,these devices are discussed by categorizing them into electrically stimulated,optically stimulated,and photoelectric synergetic synaptic devices based on stimulation of electrical and optical signals.The working mechanisms of the devices are analyzed in detail.This is followed by a discussion of the progress in mimicking synaptic functions.In addition,existing application scenarios of various synaptic devices are outlined.Furthermore,the performances and future development of the synaptic devices that could be significant for building efficient neuromorphic systems are prospected.

Review on Non-thermal Technologies for the Preservation of Fruit Juices

Liquid food industries use different preservation methods to extend the shelf life of products by reducing both enzymatic and microorganism activities.Emerging non-thermal pasteurization techniques are applied in order to avoid thermal processes maintaining the microbial safety and quality of liquid foods.Non-thermal preservation technologies used in the liquid food industry include high-pressure processing(HPP),pulsed electric field(PEF),ultraviolet light(UV-C)and ultra-sonication(US).HPP is a method to target specific organisms by applying a pressure range of 100-1,000 MPa.PEF uses short pulses of a strong electric field applied to a flowing liquid food which affects the whole cell membrane of the organism.UV-C treatment at 253.7 nm has been proven to be appropriate for maintaining liquid quality and minimal deterioration of nutrients.US is applied to liquid foods in a lower frequency range of 20-100 kHz and a higher sound intensity of 10-1,000 W/cm2 to the breakdown of cells.According to scientific literature,those methods have been applied to fruit juices like orange,apple,pear,coconut water,etc.Most of the non-thermal methods achieved the Food and Drug Administration(FDA)requirement of a 5-log reduction of microorganisms without deteriorating the sensory and nutritional attributes of fruit juices.Some of these methods have already been commercialized and others are still in a pilot scale.This study gives a comprehensive overview of published literature regarding the potential for using non-thermal pasteurization methods to extend the shelf life of different fruit juices with minimal deterioration of nutritional and sensory quality.

Altering the Residual Stress in High-Carbon Steel through Promoted Dislocation Movement and Accelerated Carbon Diffusion by Pulsed Electric Current

Residual stress in high-carbon steel affects the dimensional accuracy, structural stability, and integrity of components. Although the evolution of residual stress under an electric field has received extensive attention, its elimination mechanism has not been fully clarified. In this study, it was found that the residual stress of high-carbon steel could be effectively relieved within a few minutes through the application of a low density pulse current. The difference between the current pulse treatment and traditional heat treatment in reducing residual stress is that the electric pulse provides additional Gibbs free energy for the system, which promotes dislocation annihilation and carbon atom diffusion to form carbides, thus reducing the free energy of the system. The electroplastic and thermal effects of the pulse current promoted the movement of dislocations under the electric field, thus eliminating the internal stress caused by dislocation entanglement. The precipitation of carbides reduced the carbon content of the steel matrix and lattice shrinkage, thereby reducing the residual tensile stress. Considering that a pulsed current has the advantages of small size, small power requirement, continuous output, and continuously controllable parameters, it has broad application prospects for eliminating residual stress.

Activation of Anti-tumor Immune Response by Ablation of HCC with Nanosecond Pulsed Electric Field

Locoregional therapy is playing an increasingly important role in the non-surgical management of hepatocellular carcinoma(HCC).The novel technique of non-thermal electric ablation by nanosecond pulsed electric field has been recognized as a potential locoregional methodology for indicated HCC.This manuscript explores the most recent studies to indicate its unique anti-tumor immune response.The possible immune mechanism,termed as nano-pulse stimulation,was also analyzed.

Immune response triggered by the ablation of hepatocellular carcinoma with nanosecond pulsed electric field

Nanosecond pulsed electric field(nsPEF)is a novel,nonthermal,and minimally invasive modality that can ablate solid tumors by inducing apoptosis.Recent animal experiments show that nsPEF can induce the immunogenic cell death of hepatocellular carcinoma(HCC)and stimulate the host’s immune response to kill residual tumor cells and decrease distant metastatic tumors.nsPEF-induced immunity is of great clinical importance because the nonthermal ablation may enhance the immune memory,which can prevent HCC recurrence and metastasis.This review summarized the most advanced research on the effect of nsPEF.The possible mechanisms of how locoregional nsPEF ablation enhances the systemic anticancer immune responses were illustrated.nsPEF stimulates the host immune system to boost stimulation and prevail suppression.Also,nsPEF increases the dendritic cell loading and inhibits the regulatory responses,thereby improving immune stimulation and limiting immunosuppression in HCC-bearing hosts.Therefore,nsPEF has excellent potential for HCC treatment.

Effects of high intensity pulsed electric fields on yield and chemical composition of rose essential oil

High intensity pulsed electric fields(PEF)combined with distillation was used to extract essential oil from rose.Three main parameters,namely electric field intensity,pulse number and distillation times,which can affect the efficiency of extraction,were optimized.Then,in order to demonstrate the feasibility of the method,oil obtained under optimal conditions was compared quantitatively and qualitatively with that obtained by conventional hydro distillation.Considering the extraction yield,the optimal parameters combination was obtained with electric field intensity of 20 kV/cm,pulse number of 8 and distillation time of 2 h.PEF treatment had no significant influence on the quality of essential oils.However,there was an increase in methyl eugenol percentage,which is a disadvantage from qualitative point of view.

Removing prior particle boundaries in a powder superalloy based on the interaction between pulsed electric current and chain-like structure

The chain-like prior particle boundaries(PPBs)as a kind of stubborn harmful precipitate will hinder atomic diffusion and particle connection.They can only be broken into nanoscale through thermal deformation(1160–1200℃).Here,treated by the pulsed electric current at 800℃,PPBs were dissolved quickly as a result of the interaction between the pulsed electric current and the chain-like structure.According to the electromigration theory and the calculation results,the high current density regions will be mainly produced at the gaps due to the conductivity difference between the precipitates and the matrix.The atomic diffusion flux caused by the pulsed electric current is proportional to the current density.Therefore,the existence of a large number of gaps in the chain-like PPBs will make the high current density regions play a more positive role in fast-dissolution.

Nanosecond pulsed electric fields prime mesenchymal stem cells to peptide ghrelin and enhance chondrogenesis and osteochondral defect repair in vivo

Mesenchymal stem cells(MSCs) are important cell sources in cartilage tissue development and homeostasis,and multiple strategies have been developed to improve MSCs chondrogenic differentiation with an aim of promoting cartilage regeneration.Here we report the effects of combining nanosecond pulsed electric fields(ns PEFs) followed by treatment with ghrelin(a hormone that stimulates release of growth hormone) to regulate chondrogenesis of MSCs.ns PEFs and ghrelin were observed to separately enhance the chondrogenesis of MSCs,and the effects were significantly enhanced when the bioelectric stimulation and hormone were combined,which in turn improved osteochondral tissue repair of these cells within Sprague Dawley rats.We further found that ns PEFs can prime MSCs to be more receptive to subsequent stimuli of differentiation by upregulated Oct4/Nanog and activated JNK signaling pathway.Ghrelin initiated chondrogenic differentiation by activation of ERK1/2 signaling pathway,and RNA-seq results indicated 243 genes were regulated,and JAK-STAT signaling pathway was involved.Interestingly,the sequential order of applying these two stimuli is critical,with ns PEFs pretreatment followed by ghrelin enhanced chondrogenesis of MSCs in vitro and subsequent cartilage regeneration in vivo,but not vice versa.This synergistic prochondrogenic effects provide us new insights and strategies for future cell-based therapies.