Ion Kinetics and Neutron Generation Associated with Electromagnetic Turbulence in Laboratory-Scale Counterstreaming Plasmas

Electromagnetic turbulence and ion kinetics in counterstreaming plasmas hold great significance in laboratory astrophysics, such as turbulence field amplification and particle energization. Here, we quantitatively demonstrate for the first time how electromagnetic turbulence affects ion kinetics under achievable laboratory conditions (millimeter-scale interpenetrating plasmas with initial velocity of 2000  km/s, density of 4×10^{19}  cm^{-3}, and temperature of 100 eV) utilizing a recently developed high-order implicit particle-in-cell code without scaling transformation. It is found that the electromagnetic turbulence is driven by ion two-stream and filamentation instabilities. For the magnetized scenarios where an applied magnetic field of tens of Tesla is perpendicular to plasma flows, the growth rates of instabilities increase with the strengthening of applied magnetic field, which therefore leads to a significant enhancement of turbulence fields. Under the competition between the stochastic acceleration due to electromagnetic turbulence and collisional thermalization, ion distribution function shows a distinct super-Gaussian shape, and the ion kinetics are manifested in neutron yields and spectra. Our results have well explained the recent unmagnetized experimental observations, and the findings of magnetized scenario can be verified by current astrophysical experiments.

[Porphyromonas gingivalis outer membrane vesicles activate Toll-like receptor 2 to promote osteoclast differentiation by carrying lipopolysaccharide]

Objective: To investigate the effects of Porphyromonas gingivalis derived outer membrane vesicles (Pg OMV) on osteoclast differentiation of macrophages and its underlying mechanisms. Methods: The morphology and the size distribution of Pg OMV were analyzed by transmission electron microscopy and nanoparticle tracing analysis, respectively. The osteoclast precursors were treated with 1, 3 and 10 mg/L Pg OMV (1, 3 and 10 mg/L OMV treatment group) or phosphate buffer solution (PBS)(control group). The formation of osteoclasts was analyzed by tartrate-resistant acid phosphase (TRAP) staining and F-actin staining and real-time quantitative PCR (RT-qPCR) were used to detect the expression of Fos and matrix metallopeptidase 9 (MMP9). Polymyxin B (PMB) was used to block lipopolysaccharide (LPS) and then Pg OMV was used to treat osteoclast precursor (PMB-OMV treatment group), and OMV treatment group was used as control. TRAP and F-actin staining were used to observe the formation of osteoclasts and actin rings. The effect of Pg OMV on the expression of Toll-like receptor (TLR) 2 and TLR4 in preosteoclasts was detected by Western blotting. The osteoclast precursors were pretreated with 10, 50, 100 and 200 μmol/L C29, an inhibitor of TLR2, and then treated with Pg OMV(OMV+10, 50, 100 and 200 μmol/L C29 treatment group) and OMV treatment group without C29 pretreatment was control. TRAP and F-actin staining were used to observe the formation of osteoclasts and actin rings. The osteoclast precursor cells were treated with OMV (OMV treatment group) and OMV incubated with PMB (PMB-OMV treatment group) and the expression of TLR2 in osteoclast precursor was detected by Western blotting. Results: Pg OMV showed classical vesicular structures, and the average particle size of Pg OMV were 179.2 nm. A large number of actin rings were observed in the 3 and 10 mg/L OMV treatment groups. The percentages of TRAP-positive osteoclast area in 3 mg/L OMV treatment group [(22.6±2.1)%] and 10 mg/L OMV treatment group [(32.0±2.3)%] were significantly increased compared with control group [(4.9±0.5)%] (P<0.001). Compared with the control group (1.000±0.029), the mRNA relative expression of Fos in 3 mg/L OMV treatment group (1.491±0.114) and 10 mg/L OMV treatment group (1.726±0.254) was significantly increased (P=0.013, P=0.001). Compared with the control group (1.007±0.148), the mRNA relative expression of MMP9 in the group of 10 mg/L OMV (2.232±0.097) was significantly increased (P<0.001). Actin ring formation was less in PMB-OMV treatment groups than in OMV treatment groups. The proportion of TRAP-positive osteoclasts area [(14.8±3.8)%] in PMB-OMV treatment group was significantly lower than OMV treatment group [(31.5±6.7) %] (P=0.004). The relative expression of TLR2 in OMV treatment group (1.359±0.134) was significantly higher than that in the control group (1.000±0.000) (t=4.62, P=0.044). Compared with the OMV treatment group [(29.4±1.7)%], 50, 100 and 200 μmol/L C29 significantly decreased the formation of osteoclasts [(24.0±1.7)%, (18.5±2.1)%, (9.1±1.3) %] (P=0.026, P<0.001, P<0.001). TLR2 protein expression in PMB-OMV group (0.780±0.046) was significantly lower than that in OMV group (1.000±0.000)(t=8.32, P=0.001). Conclusions: Pg OMV can promote osteoclast differentiation by carrying LPS, TLR2 plays an important role in Pg OMV mediated osteoclast differentiation.

Dynamic stabilization of ablative Rayleigh-Taylor instability in the presence of a temporally modulated laser pulse

This paper presents a numeric study of the dynamic stabilization of the ablative Rayleigh-Taylor instability (ARTI) in the presence of a temporally modulated laser pulse. The results show that the specially modulated laser produces a dynamically stabilized configuration near the ablation front. The physical features of the relevant laser-driven parameters in the unperturbed ablative flows have been analyzed to reveal the inherent stability mechanism underlying the dynamically stabilized configuration. A single-mode ARTI for the modulated laser pulse is first compared with that of the unmodulated laser pulse. The results show that the modulated laser stabilizes the surface perturbations and reduces the linear growth rate and enhancement of the cutoff wavelength. For multimode perturbations, the dynamic stabilization effect of the modulated laser pulse contributes to suppress the small-scale structure and reduce the width of the mixing layer. Moreover, the results show that the stabilization effect of the modulated laser pulse decreases as the maximum wavelength increases.

Anomalous staged hot-electron acceleration by two-plasmon decay instability in magnetized plasmas

We present a staged hot-electron acceleration mechanism of the two-plasmon decay (TPD) instability in the transverse magnetic field under the parameters relevant to inertial confinement fusion experiments. After being accelerated by the forward electron plasma wave (FEPW) of TPD, the hot-electrons can be anomalously accelerated again by the backward electron plasma wave (BEPW) of TPD and then obtain higher energy. Moreover, the surfatron acceleration mechanism of TPD in the magnetic field is also confirmed, the electrons trapped by the TPD daughter EPWs are accelerated in the direction along the wave front. Interestingly, the velocity of electrons accelerated by surfing from the FEPW is quite easily close to the BEPW phase velocity, which markedly enhances the efficiency of the staged acceleration. The coexistence of these two acceleration mechanisms leads to a significant increase of energetic electrons generated by TPD in the magnetic field. Meanwhile the EPWs are dissipated, TPD instability is effectively suppressed, and the laser transmission increases.

Experimental confirmation of driving pressure boosting and smoothing for hybrid-drive inertial fusion at the 100-kJ laser facility

In laser-driven inertial confinement fusion, driving pressure boosting and smoothing are major challenges. A proposed hybrid-drive (HD) scheme can offer such ideal HD pressure performing stable implosion and nonstagnation ignition. Here we report that in the hemispherical and planar ablator targets installed in the semicylindrical hohlraum scaled down from the spherical hohlraum of the designed ignition target, under indirect-drive (ID) laser energies of ~43-50 kJ, the peak radiation temperature of 200 ± 6 eV is achieved. And using only direct-drive (DD) laser energies of 3.6-4.0 kJ at an intensity of 1.8 × 1015 W/cm2, in the hemispherical and planar targets the boosted HD pressures reach 3.8-4.0 and 3.5-3.6 times the radiation ablation pressure respectively. In all the above experiments, significant HD pressure smoothing and the important phenomenon of how a symmetric strong HD shock suppresses the asymmetric ID shock pre-compressed fuel are demonstrated. The backscattering and hot-electron energy fractions both of which are about one-third of that in the DD scheme are also measured.

High-Flux Neutron Generator Based on Laser-Driven Collisionless Shock Acceleration

A novel compact high-flux neutron generator with a pitcher-catcher configuration based on laser-driven collisionless shock acceleration (CSA) is proposed and experimentally verified. Different from those that previously relied on target normal sheath acceleration (TNSA), CSA in nature favors not only acceleration of deuterons (instead of hydrogen contaminants) but also increasing of the number of deuterons in the high-energy range, therefore having great advantages for production of high-flux neutron source. The proof-of-principle experiment has observed a typical CSA plateau feature from 2 to 6 MeV in deuteron energy spectrum and measured a forward neutron flux with yield 6.6×10^{7}  n/sr from the LiF catcher target, an order of magnitude higher than the compared TNSA case, where the laser intensity is 10^{19}  W/cm^{2}. Self-consistent simulations have reproduced the experimental results and predicted that a high-flux forward neutron source with yield up to 5×10^{10}  n/sr can be obtained when laser intensity increases to 10^{21}  W/cm^{2} under the same laser energy.

NADPH-dependent ROS accumulation contributes to the impaired osteogenic differentiation of periodontal ligament stem cells under high glucose conditions

Diabetes mellitus is an established risk factor for periodontal disease that can aggravate the severity of periodontal inflammation and accelerate periodontal destruction. The chronic high glucose condition is a hallmark of diabetes-related pathogenesis, and has been demonstrated to impair the osteogenic differentiation of periodontal ligament stem cells (PDLSCs), leading to delayed recovery of periodontal defects in diabetic patients. Reactive oxygen species (ROS) are small molecules that can influence cell fate determination and the direction of cell differentiation. Although excessive accumulation of ROS has been found to be associated with high glucose-induced cell damage, the underlying mechanisms remain unclear. Nicotinamide adenine dinucleotide phosphate (NADPH) is an important electron donor and functions as a critical ROS scavenger in antioxidant systems. It has been identified as a key mediator of various biological processes, including energy metabolism and cell differentiation. However, whether NADPH is involved in the dysregulation of ROS and further compromise of PDLSC osteogenic differentiation under high glucose conditions is still not known. In the present study, we found that PDLSCs incubated under high glucose conditions showed impaired osteogenic differentiation, excessive ROS accumulation and increased NADPH production. Furthermore, after inhibiting the synthesis of NADPH, the osteogenic differentiation of PDLSCs was significantly enhanced, accompanied by reduced cellular ROS accumulation. Our findings demonstrated the crucial role of NADPH in regulating cellular osteogenic differentiation under high glucose conditions and suggested a new target for rescuing high glucose-induced cell dysfunction and promoting tissue regeneration in the future.

Biotin-Avidin System-Based Delivery Enhances the Therapeutic Performance of MSC-Derived Exosomes

Exosomes (EXs) shed by mesenchymal stem cells (MSCs) are potent therapeutic agents that promote wound healing and regeneration, but when used alone in vivo, their therapeutic potency is diminished by rapid clearance and bioactivity loss. Inspired by the biotin-avidin interaction, we developed a simple yet versatile method for the immobilization of MSC-derived EXs (MSC-EXs) into hydrogels and achieved sustained release for regenerative purposes. First, biotin-modified gelatin methacryloyl (Bio-GelMA) was fabricated by grafting NHS-PEG₁₂-biotin onto the amino groups of GelMA. Biotin-modified MSC-EXs (Bio-EXs) were then synthesized using an in situ self-assembling biotinylation strategy, which provided sufficient binding sites for MSC-EX delivery with little effect on their cargo composition. Thereafter, Bio-EXs were immobilized in Bio-GelMA via streptavidin to generate Bio-GelMA@Bio-EX hydrogels. An in vitro analysis demonstrated that Bio-EXs could be taken up by macrophages and exerted immunomodulatory effects similar to those of MSC-EXs, and Bio-GelMA@Bio-EX hydrogels provided sustained release of MSC-EXs for 7 days. After subcutaneous transplantation, a more constant retention of MSC-EXs in Bio-GelMA@Bio-EX hydrogels was observed for up to 28 days. When placed in an artificial periodontal multitissue defect, the functionalized hydrogels exhibited an optimized therapeutic performance to regrow complex periodontal tissues, including acellular cementum, periodontal ligaments (PDLs), and alveolar bone. In this context, Bio-GelMA@Bio-EX hydrogels exerted a robust immunomodulatory effect that promoted macrophage polarization toward an M2 phenotype. Our findings demonstrate that MSC-EXs delivered with the aid of the biotin-avidin system exhibit robust macrophage-modulating and repair-promoting functions and suggest a universal approach for the development of MSC-EX-functionalized biomaterials for advanced therapies.

Long non-coding RNA AC018926.2 regulates palmitic acid exposure-compromised osteogenic potential of periodontal ligament stem cells via the ITGA2/FAK/AKT pathway

Although obesity has been proposed as a risk factor for periodontitis, the influence of excessive fat accumulation on the development of periodontitis and periodontal recovery from disease remains largely unknown. This study investigated the cellular response of periodontal ligament stem cells (PDLSCs) to elevated levels of a specific fatty acid, namely, palmitic acid (PA). The mechanism by which PA exposure compromises the osteogenic potential of cells was also explored. It was found that exposure of PDLSCs to abundant PA led to decreased cell osteogenic differentiation. Given that long non-coding RNAs (lncRNAs) play a key role in the stem cell response to adverse environmental stimuli, we screened the lncRNAs that were differentially expressed in PDLSCs following PA exposure using lncRNA microarray analysis, and AC018926.2 was identified as the lncRNA that was most sensitive to PA. Next, gain/loss-of-function studies illustrated that AC018926.2 was an important regulator in PA-mediated osteogenic differentiation of PDLSCs. Mechanistically, AC018926.2 upregulated integrin α2 (ITGA2) expression and therefore activated ITGA2/FAK/AKT signalling. Further functional studies revealed that inactivation of ITGA2/FAK/AKT signalling by silencing ITGA2 counteracted the pro-osteogenic effect induced by AC018926.2 overexpression. Moreover, the results of bioinformatics analysis and RNA immunoprecipitation assay suggested that AC018926.2 might transcriptionally regulate ITGA2 expression by binding to PARP1 protein. Our data suggest that AC018926.2 may serve as a therapeutic target for the management of periodontitis in obese patients.

Roles of extracellular vesicles in periodontal homeostasis and their therapeutic potential

Periodontal tissue is a highly dynamic and frequently stimulated area where homeostasis is easily destroyed, leading to proinflammatory periodontal diseases. Bacteria-bacteria and cell-bacteria interactions play pivotal roles in periodontal homeostasis and disease progression. Several reviews have comprehensively summarized the roles of bacteria and stem cells in periodontal homeostasis. However, they did not describe the roles of extracellular vesicles (EVs) from bacteria and cells. As communication mediators evolutionarily conserved from bacteria to eukaryotic cells, EVs secreted by bacteria or cells can mediate interactions between bacteria and their hosts, thereby offering great promise for the maintenance of periodontal homeostasis. This review offers an overview of EV biogenesis, the effects of EVs on periodontal homeostasis, and recent advances in EV-based periodontal regenerative strategies. Specifically, we document the pathogenic roles of bacteria-derived EVs (BEVs) in periodontal dyshomeostasis, focusing on plaque biofilm formation, immune evasion, inflammatory pathway activation and tissue destruction. Moreover, we summarize recent advancements in cell-derived EVs (CEVs) in periodontal homeostasis, emphasizing the multifunctional biological effects of CEVs on periodontal tissue regeneration. Finally, we discuss future challenges and practical perspectives for the clinical translation of EV-based therapies for periodontitis.

Gold nanoparticles targeting the autophagy-lysosome system to combat the inflammation-compromised osteogenic potential of periodontal ligament stem cells: From mechanism to therapy

Although substantial data indicate that the osteogenic potential of periodontal ligament stem cells (PDLSCs) is compromised under inflammatory conditions, the underlying mechanism remains largely unexplored. In this study, we found that both the autophagy levels and autophagic flux levels were decreased in PDLSCs incubated under inflammatory conditions (I-PDLSCs). Based on the increased expression of LC3 II (at an autophagy level) and decreased accumulation of LC3 II (at an autophagic flux level) in I-PDLSCs, we speculated that the disruption of I-PDLSC autophagy arose from dysfunction of the cellular autophagy-lysosome system. Subsequently, our hypothesis was demonstrated by inhibited autophagosome-lysosome fusion, damaged lysosomal function, and suppressed activation of transcription factor EB (TFEB, a master regulator of the autophagy-lysosome system) in I-PDLSCs and verified by TFEB overexpression in I-PDLSCs. We found that gold nanoparticle (Au NP) treatment rescued the osteogenic potential of I-PDLSCs by restoring the inflammation-compromised autophagy-lysosome system. In this context, Au NP ceased to be effective when TFEB was knocked down in PDLSCs. Our data demonstrate the crucial role of the autophagy-lysosome system in cellular osteogenesis under inflammatory conditions and suggest a new target for rescuing inflammation-induced cell dysfunction using nanomaterials to aid cell biology and tissue regeneration.

Metformin combats high glucose-induced damage to the osteogenic differentiation of human periodontal ligament stem cells via inhibition of the NPR3-mediated MAPK pathway

Background

High glucose-induced damage to the osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) has long been a challenge to periodontal regeneration for diabetic individuals. Metformin is an anti-hyperglycemic drug that exhibits abundant biological activities associated with cell metabolism and downstream tissue regeneration. However, how metformin combats damage to PDLSC osteogenic differentiation under high glucose and the underlying mechanisms remain unknown.

Methods

Osteogenic differentiation of PDLSCs was assessed by alkaline phosphatase (ALP) staining, ALP activity, Alizarin Red staining and quantitative assay, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analysis. RNA-seq analysis was performed to screen target genes of metformin, and the effects of target genes were confirmed using lentivirus transfection. Western blot analysis was also used to detect the protein level of underlying signaling pathways.

Results

We found that osteogenic differentiation of PDLSCs under high glucose was decreased, and metformin addition enhanced this capacity of differentiation. Furthermore, the results of RNA-seq analysis showed that natriuretic peptide receptor 3 (NPR3) was upregulated in PDLSCs under high glucose and downregulated after metformin addition. When the underlying pathways involved were investigated, we found that upregulation of NPR3 can compromise the metformin-enhanced PDLSC osteogenic differentiation and activate the MAPK pathway (especially the p38 MAPK and Erk1/2 pathway), and that inhibition of the NPR3-mediated p38 MAPK or Erk1/2 pathway enhanced the osteogenic differentiation of PDLSCs under high glucose.

Conclusions

The present study suggests that metformin may enhance the osteogenic differentiation of PDLSCs under high glucose via downregulation of NPR3 and inhibition of its downstream MAPK pathway. This is the first report identifying the involvement of NPR3-mediated MAPK pathway in the metformin-enhanced osteogenic differentiation, indicating that NPR3 antagonists, such as metformin, may be feasible therapeutics for periodontal tissue regeneration in diabetic individuals.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-022-02992-z.

Suprathermal electrons from the anti-Stokes Langmuir decay instability cascade

The study of parametric instabilities has played a crucial role in understanding energy transfer to plasma and, with that, the development of key applications such as inertial confinement fusion. When the densities are between 0.11n_{c}≲n_{e}≲0.14n_{c} and the electron temperature is in inertial confinement fusion-relevant temperatures, anomalous hot electrons with kinetic energies above 100keV are generated. Here a new electron acceleration mechanism-the anti-Stokes Langmuir decay instability cascade of forward stimulated Raman scattering-is investigated. This mechanism potentially explains anomalous energetic electron generation in indirectly driven inertial confinement fusion experiments, it also provides a new way of accelerating electrons to higher energy for applications such as novel x-ray sources.

Polarization conversion in the caviton driven by linearly polarized lasers

In one-dimensional particle-in-cell simulations of a plasma irradiated by linearly polarized lasers from both sides of boundaries, it is found that there is an appreciable growth of the electromagnetic field in cavitons in the transverse direction perpendicular to the direction of polarization, which indicates the polarization conversion of the electromagnetic field in cavitons. This paper demonstrates the mechanism of this phenomenon based on parametric resonance induced by ponderomotive force with twice the frequency of the electromagnetic radiation in the caviton. We develop a theoretical model and verify it with simulation results. This phenomenon contributes to the heating and acceleration of particles and traps more EM energy in cavitons.

Nuclear disarmament verification based on (n,γ) reaction using physical encryption technology

To reduce the risk of leaking confidential information in nuclear arms control, we propose a new arms control inspection concept based on neutron activation analysis, in conjunction with physical shielding technology to distort the energy and propagation path of the outgoing particles in the physical domain. The reliability and security of this authentication concept are demonstrated using Monte Carlo simulations. It turns out that the concept can readily identify isotope cheats and two typical geometric cheats without revealing sensitive information about the inspected items.

Absolute stimulated Brillouin side scattering in an inhomogeneous flowing plasma

Theory of absolute stimulated Brillouin side scattering in an inhomogeneous flowing plasma is presented and verified numerically. The linearized coupling equations are transformed into a Schrödinger equation in k space and solved as an eigenvalue problem. Analytic threshold, growth rate, and scattering geometry are obtained for the pump laser with arbitrary incidence angle. Numerical solutions of the coupling equations show good agreements between the theoretical and numerical absolute thresholds when ion-acoustic wave damping is not too large, and thus an old but famous threshold in [Phys. Fluids 17, 1211 (1974)PFLDAS0031-917110.1063/1.1694867] is corrected. It also indicates that the theoretical analysis is not accurate for strong dampings, since it will overestimate the absolute threshold. Possibility of finding such instability in the current experiments is also discussed.

Scaling laws for laser-driven ion acceleration from nanometer-scale ultrathin foils

Laser-driven ion acceleration has attracted global interest for its potential towards the development of a new generation of compact, low-cost accelerators. Remarkable advances have been seen in recent years with a substantial proton energy increase in experiments, when nanometer-scale ultrathin foil targets and high-contrast intense lasers are applied. However, the exact acceleration dynamics and particularly the ion energy scaling laws in this novel regime are complex and still unclear. Here, we derive a scaling law for the attainable maximum ion energy from such laser-irradiated nanometer-scale foils based on analytical theory and multidimensional particle-in-cell simulations, and further show that this scaling law can be used to accurately describe experimental data over a large range of laser and target parameters on different facilities. This provides crucial references for parameter design and experimentation of the future laser devices towards various potential applications.

Onset of inverse magnetic energy transfer in collisionless turbulent plasmas

Inverse magnetic energy transfer from small to large scales is a key physical process for the origin of large-scale strong magnetic fields in the universe. However, so far, from the magnetohydrodynamic perspective, the onset of inverse transfer is still not fully understood, especially the underlying dynamics. Here, we use both two-dimensional and three-dimensional particle-in-cell simulations to show the self-consistent dynamics of inverse transfer in collisionless decaying turbulent plasmas. Using the space filtering technique in theory and numerical analyses, we identify magnetic reconnection as the onset and fundamental drive for inverse transfer, where, specifically, the subscale electromotive force driven by magnetic reconnection do work on the large-scale magnetic field, resulting in energy transfer from small to large scales. The mechanism is also verified by the strong correlations in locations and characteristic scales between inverse transfer and magnetic reconnection.

Melatonin induces the rejuvenation of long-term ex vivo expanded periodontal ligament stem cells by modulating the autophagic process

Background

Stem cells that have undergone long-term ex vivo expansion are most likely functionally compromised (namely cellular senescence) in terms of their stem cell properties and therapeutic potential. Due to its ability to attenuate cellular senescence, melatonin (MLT) has been proposed as an adjuvant in long-term cell expansion protocols, but the mechanism underlying MLT-induced cell rejuvenation remains largely unknown.

Methods

Human periodontal ligament stem cells (PDLSCs) were isolated and cultured ex vivo for up to 15 passages, and cells from passages 2, 7, and 15 (P2, P7, and P15) were used to investigate cellular senescence and autophagy change in response to long-term expansion and indeed the following MLT treatment. Next, we examined whether MLT could induce cell rejuvenation by restoring the autophagic processes of damaged cells and explored the underlying signaling pathways. In this context, cellular senescence was indicated by senescence-associated β-galactosidase (SA-β-gal) activity and by the expression of senescence-related proteins, including p53, p21, p16, and γ-H2AX. In parallel, cell autophagic processes were evaluated by examining autophagic vesicles (by transmission electronic microscopy), autophagic flux (by assessing mRFP-GFP-LC3-transfected cells), and autophagy-associated proteins (by Western blot assay of Atg7, Beclin-1, LC3-II, and p62).

Results

We found that long-term in vitro passaging led to cell senescence along with impaired autophagy. As expected, MLT supplementation not only restored cells to a younger state but also restored autophagy in senescent cells. Additionally, we demonstrated that autophagy inhibitors could block MLT-induced cell rejuvenation. When the underlying signaling pathways involved were investigated, we found that the MLT receptor (MT) mediated MLT-related autophagy restoration by regulating the PI3K/AKT/mTOR signaling pathway.

Conclusions

The present study suggests that MLT may attenuate long-term expansion-caused cellular senescence by restoring autophagy, most likely via the PI3K/AKT/mTOR signaling pathway in an MT-dependent manner. This is the first report identifying the involvement of MT-dependent PI3K/AKT/mTOR signaling in MLT-induced autophagy alteration, indicating a potential of autophagy-restoring agents such as MLT to be used in the development of optimized clinical-scale cell production protocols.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02322-9.

New α-Emitting Isotope ^{214}U and Abnormal Enhancement of α-Particle Clustering in Lightest Uranium Isotopes

A new α-emitting isotope ^{214}U, produced by the fusion-evaporation reaction ^{182}W(^{36}Ar,4n)^{214}U, was identified by employing the gas-filled recoil separator SHANS and the recoil-α correlation technique. More precise α-decay properties of even-even nuclei ^{216,218}U were also measured in the reactions of ^{40}Ar, ^{40}Ca beams with ^{180,182,184}W targets. By combining the experimental data, improved α-decay reduced widths δ^{2} for the even-even Po-Pu nuclei in the vicinity of the magic neutron number N=126 are deduced. Their systematic trends are discussed in terms of the N_{p}N_{n} scheme in order to study the influence of proton-neutron interaction on α decay in this region of nuclei. It is strikingly found that the reduced widths of ^{214,216}U are significantly enhanced by a factor of two as compared with the N_{p}N_{n} systematics for the 84≤Z≤90 and N<126 even-even nuclei. The abnormal enhancement is interpreted by the strong monopole interaction between the valence protons and neutrons occupying the π1f_{7/2} and ν1f_{5/2} spin-orbit partner orbits, which is supported by the large-scale shell model calculation.

Periodontitis-compromised dental pulp stem cells secrete extracellular vesicles carrying miRNA-378a promote local angiogenesis by targeting Sufu to activate the Hedgehog/Gli1 signalling

Objectives

Previously, our investigations demonstrated robust pro‐angiogenic potentials of extracellular vesicles secreted by periodontitis‐compromised dental pulp stem cells (P‐EVs) when compared to those from healthy DPSCs (H‐EVs), but the underlying mechanism remains unknown.

Materials and methods

Here, circulating microRNAs (miRNAs) specifically found in P‐EVs (compared with H‐EVs) were identified by Agilent miRNA microarray analysis, and the roles of the candidate miRNA in P‐EV‐enhanced cell angiogenesis were confirmed by cell transfection and RNA interference methods. Next, the direct binding affinity between the candidate miRNA and its target gene was evaluated by luciferase reporter assay. CCK‐8, transwell/scratch wound healing and tube formation assays were established to investigate the proliferation, migration, and tube formation abilities of endothelial cells (ECs). Western blot was employed to measure the protein levels of Hedgehog/Gli1 signalling pathway components and angiogenesis‐related factors.

Results

The angiogenesis‐related miRNA miR‐378a was found to be enriched in P‐EVs, and its role in P‐EV‐enhanced cell angiogenesis was confirmed, wherein Sufu was identified as a downstream target gene of miR‐378a. Functionally, silencing of Sufu stimulated EC proliferation, migration and tube formation by activating Hedgehog/Gli1 signalling. Further, we found that incubation with P‐EVs enabled the transmission of P‐EV‐contained miR‐378a to ECs. Subsequently, the expressions of Sufu, Gli1 and vascular endothelial growth factor in ECs were significantly influenced by P‐EV‐mediated miR‐378a transmission.

Conclusions

These data suggest that P‐EVs carrying miR‐378a promote EC angiogenesis by downregulating Sufu to activate the Hedgehog/Gli1 signalling pathway. Our findings reveal a crucial role for EV‐derived miR‐378a in cell angiogenesis and hence offer a new target for modifying stem cells and their secreted EVs to enhance vessel regenerative potential.

Particle-in-cell simulation method for macroscopic degenerate plasmas

Nowadays hydrodynamic equations coupled with external equation of states provided by quantum mechanical calculations is a widely used approach for simulations of macroscopic degenerate plasmas. Although such an approach is proven to be efficient and shows many good features, especially for large scale simulations, it encounters intrinsic challenges when involving kinetic effects. As a complement, here we have invented a fully kinetic numerical approach for macroscopic degenerate plasmas. This approach is based on first principle Boltzmann-Uhling-Uhlenbeck equations coupled with Maxwell's equation, and is eventually achieved via an existing particle-in-cell simulation code named LAPINS. In this approach, degenerate particles obey Fermi-Dirac statistics and nondegenerate particles follow the typical Maxwell-Boltzmann statistics. The equation of motion of both degenerate and nondegenerate particles are governed by long range collective electromagnetic fields and close particle-particle collisions. Especially, Boltzmann-Uhling-Uhlenbeck collisions ensure that evolution of degenerate particles is enforced by the Pauli exclusion principle. The code is applied to several benchmark simulations, including electronic conductivity for aluminium with varying temperatures from 2 eV to 50 eV, thermalization of alpha particles in a cold fuel shell in inertial confinement fusion, and rapid heating of solid sample by short and intense laser pulses.

Growth and saturation of stimulated Raman scattering in two overlapping laser beams

Two-dimensional particle-in-cell simulations are presented of the linear and nonlinear developments of stimulated Raman scattering in two overlapping laser beams. The development of the most unstable mode in the linear stage is consistent with a previous paper [C. Z. Xiao et al., Phys. Plasmas 26, 062109 (2019)PHPAEN1070-664X10.1063/1.5096850] where SL mode (two beams share a common scattered light) is dominant in the overlapping region. This mode is enhanced with plasma density and correlation of beam polarizations. When lasers are cross-polarized, it backs to the single-beam Raman backscattering with weak intensity. Trapping-induced nonlinear frequency shift leads to the saturation of SL mode by detuning the coupling and broadening the spectrum. An interesting result that SL mode becomes stronger as the incidence angle increases is contrary to the theoretical prediction and it is a consequence of less efficient saturation in the nonlinear stage.

Dynamics of bond breaking and formation in polyethylene near shock front

In a systematic study of shock wave propagating in crystalline polyethylenes using molecular dynamics method and the electron force field (eFF) potential, we show that microscopic structure of shock front is significantly affected by the anisotropy of long carbon chain and the bond breaking and recombination dynamics. However, macroscopic properties measured in Hugoniot experiments, such as compression ratio and shock velocity, are not sensitive to carbon chain anisotropy and bond dynamics. Our work also display that hydrogen molecules are formed when the piston speed is in the region between 10 km/s and 30 km/s. However, carbon-hydrogen pair distribution function does not display an indication of carbon-hydrogen phase segregation.

Short-Lived α-Emitting Isotope ^{222}Np and the Stability of the N=126 Magic Shell

A new, very short-lived neutron-deficient isotope ^{222}Np was produced in the complete-fusion reaction ^{187}Re(^{40}Ar,5n)^{222}Np, and observed at the gas-filled recoil separator SHANS. The new isotope ^{222}Np was identified by employing a recoil-α correlation measurement, and six α-decay chains were established for it. The decay properties of ^{222}Np with E_{α}=10016(33)  keV and T_{1/2}=380_{-110}^{+260}  ns were determined experimentally. The α-decay systematics of Np isotopes is improved by adding the new data for ^{222}Np, which validates the N=126 shell effect in Np isotopes. The evolution of the N=126 shell closure is discussed in the neutron-deficient nuclei up to Np within the framework of α-decay reduced width.

Uniform warm dense matter formed by direct laser heating in the presence of external magnetic fields

With the recent realization of kilotesla quasistatic magnetic fields, the interaction of a laser with magnetized solids enters an unexplored new regime. In particular, a circularly polarized (CP) laser pulse may propagate in a highly magnetized plasma of any high density without encountering cutoff reflection in the whistler mode. With this, we propose a scheme for producing uniform warm dense matter (WDM) by direct laser heating with a CP laser irradiating onto the target along the magnetic field. It is shown by particle-in-cell simulations, which include advanced ionization dynamics and collision dynamics, moderately intense right-hand CP laser light at 10^{15}W/cm^{2} can propagate in solid aluminum and heat it efficiently to the 100 eV level within picoseconds. By using two laser pulses irradiating from two sides of a thin solid target, uniform heating to WDM can be achieved. This provides a controllable way to create WDM at different temperatures.

Exosomes derived from M0, M1 and M2 macrophages exert distinct influences on the proliferation and differentiation of mesenchymal stem cells

Background

Different phenotypes of macrophages (M0, M1 and M2 Mφs) have been demonstrated to play distinct roles in regulating mesenchymal stem cells in various in vitro and in vivo systems. Our previous study also found that cell-conditioned medium (CM) derived from M1 Mφs supported the proliferation and adipogenic differentiation of bone marrow mesenchymal stem cells (BMMSCs), whereas CM derived from either M0 or M2 Mφs showed an enhanced effect on cell osteogenic differentiation. However, the underlying mechanism remains incompletely elucidated. Exosomes, as key components of Mφ-derived CM, have received increasing attention. Therefore, it is possible that exosomes may modulate the effect of Mφ-derived CM on the property of BMMSCs. This hypothesis was tested in the present study.

Methods

In this study, RAW264.7 cells were induced toward M1 or M2 polarization with different cytokines, and exosomes were isolated from the unpolarized (M0) and polarized (M1 and M2) Mφs. Mouse BMMSCs were then cultured with normal complete medium or inductive medium supplemented with M0-Exos, M1-Exos or M2-Exos. Finally, the proliferation ability and the osteogenic, adipogenic and chondrogenic differentiation capacity of the BMMSCs were measured and analyzed.

Results

We found that only the medium containing M1-Exos, rather than M0-Exos or M2-Exos, supported cell proliferation and osteogenic and adipogenic differentiation. This was inconsistent with CM-based incubation. In addition, all three types of exosomes had a suppressive effect on chondrogenic differentiation.

Conclusion

Although our data demonstrated that exosomes and CM derived from the same phenotype of Mφs didn’t exert exactly the same cellular influences on the cocultured stem cells, it still confirmed the hypothesis that exosomes are key regulators during the modulation effect of Mφ-derived CM on BMMSC property.

Suppression of histone deacetylases by SAHA relieves bone cancer pain in rats via inhibiting activation of glial cells in spinal dorsal horn and dorsal root ganglia

BACKGROUND

Robust activation of glial cells has been reported to occur particularly during the pathogenesis of bone cancer pain (BCP). Researchers from our group and others have shown that histone deacetylases (HDACs) play a significant role in modulating glia-mediated immune responses; however, it still remains unclear whether HDACs are involved in the activation of glial cells during the development of BCP.

METHODS

BCP model was established by intra-tibia tumor cell inoculation (TCI). The expression levels and distribution sites of histone deacetylases (HDACs) in the spinal dorsal horn and dorsal root ganglia were evaluated by Western blot and immunofluorescent staining, respectively. Suberoylanilide hydroxamic acid (SAHA), a clinically used HDAC inhibitor, was then intraperitoneally and intrathecally injected to rescue the increased expression levels of HDAC1 and HDAC2. The analgesic effects of SAHA administration on BCP were then evaluated by measuring the paw withdrawal thresholds (PWTs). The effects of SAHA on activation of glial cells and expression of proinflammatory cytokines (TNF-α, IL-1β, and IL-6) in the spinal dorsal horn and dorsal root ganglia of TCI rats were further evaluated by immunofluorescent staining and Western blot analysis. Subsequently, the effects of SAHA administration on tumor growth and cancer cell-induced bone destruction were analyzed by hematoxylin and eosin (HE) staining and micro-CT scanning.

RESULTS

TCI caused rapid and long-lasting increased expression of HDAC1/HDAC2 in glial cells of the spinal dorsal horn and dorsal root ganglia. Inhibiting HDACs by SAHA not only reversed TCI-induced upregulation of HDACs but also inhibited the activation of glial cells in the spinal dorsal horn and dorsal root ganglia, and relieved TCI-induced mechanical allodynia. Further, we found that SAHA administration could not prevent cancer infiltration or bone destruction in the tibia, which indicated that the analgesic effects of SAHA were not due to its anti-tumor effects. Moreover, we found that SAHA administration could inhibit GSK3β activity in the spinal dorsal horn and dorsal root ganglia, which might contributed to the relief of BCP.

CONCLUSION

Our findings suggest that HDAC1 and HDAC2 are involved in the glia-mediated neuroinflammation in the spinal dorsal horn and dorsal root ganglia underlying the pathogenesis of BCP, which indicated that inhibiting HDACs by SAHA might be a potential strategy for pain relief of BCP.

Giant Isolated Attosecond Pulses from Two-Color Laser-Plasma Interactions

A new regime in the interaction of a two-color (ω,2ω) laser with a nanometer-scale foil is identified, resulting in the emission of extremely intense, isolated attosecond pulses-even in the case of multicycle lasers. For foils irradiated by lasers exceeding the blow-out field strength (i.e., capable of fully separating electrons from the ion background), the addition of a second harmonic field results in the stabilization of the foil up to the blow-out intensity. This is then followed by a sharp transition to transparency that essentially occurs in a single optical cycle. During the transition cycle, a dense, nanometer-scale electron bunch is accelerated to relativistic velocities and emits a single, strong attosecond pulse with a peak intensity approaching that of the laser field.

The proangiogenic effects of extracellular vesicles secreted by dental pulp stem cells derived from periodontally compromised teeth

Background

Although dental pulp stem cells (DPSCs) isolated from periodontally compromised teeth (P-DPSCs) have been demonstrated to retain pluripotency and regenerative potential, their use as therapeutics remains largely unexplored. In this study, we investigated the proangiogenic effects of extracellular vesicles (EVs) secreted by P-DPSCs using in vitro and in vivo testing models.

Methods

Patient-matched DPSCs derived from periodontally healthy teeth (H-DPSCs) were used as the control for P-DPSCs. Conditioned media (CMs) derived from H-DPSCs and P-DPSCs (H-CM and P-CM), CMs derived from both cell types pretreated with the EV secretion blocker GW4869 (H-GW and P-GW), and EVs secreted by H-DPSCs and P-DPSCs (H-EVs and P-EVs) were prepared to test their proangiogenic effects on endothelial cells (ECs). Cell proliferation, migration, and tube formation were assessed using the Cell Counting Kit-8 (CCK-8), transwell/scratch wound healing, and Matrigel assays, respectively. Specifically, quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blot analysis were used to examine the expression levels of angiogenesis-related genes/proteins in ECs in response to EV-based incubation. Finally, a full-thickness skin defect model was applied to test the effects of EVs on wound healing and new vessel formation.

Results

Both H-CM and P-CM promoted EC angiogenesis, but the proangiogenic effects were compromised when ECs were incubated in H-GW and P-GW, wherein the EV secretion was blocked by pretreatment with GW4869. In EV-based incubations, although both H-EVs and P-EVs were found to enhance the angiogenesis-related activities of ECs, P-EVs exerted a more robust potential to stimulate EC proliferation, migration, and tube formation. In addition, P-EVs led to higher expression levels of angiogenesis-related genes/proteins in ECs than H-EVs. Similarly, both P-EVs and H-EVs were found to accelerate wound healing and promote vascularization across skin defects in mice, but wounds treated with P-EVs resulted in a quicker healing outcome and enhanced new vessel formation.

Conclusions

The findings of the present study provide additional evidence that P-DPSCs derived from periodontally diseased teeth represent a potential source of cells for research and therapeutic use. Particularly, the proangiogenic effects of P-EVs suggest that P-DPSCs may be used to promote new vessel formation in cellular therapy and regenerative medicine.

Coupling effects and thin-shell corrections for surface instabilities of cylindrical fluid shells

We show that when linear azimuthal perturbations on the surfaces of a fluid shell are regrouped according to α^{m}, they can be divided into Bell model terms, coupling terms, and the newly identified thin-shell correction terms, where α is the ratio of R_{out} to R_{in}, and m is the mode number of a given unstable mode on the surfaces. It is also revealed that α^{m} is a convenient index variable of coupling effects, with which we show that the evolution of instability is composed of three stages, i.e., strongly coupled stage, transition stage, and uncoupled stage. Roughly, when α^{m}<6, the fluid shell is in the strongly coupled stage, where both coupling effects and the newly identified thin-shell corrections play important roles. Strong feed through is expected to be observed. The uncoupled stage is reached at α^{m}∼36, where Bell's model of independent surface holds. In between is the transition stage, where mode competitions on the two surfaces are expected to be observed. These results afford an intuitive picture which is easy to use in guiding the design of experiments. They may also help to quickly grasp major features of instability experiments of this kind.

Surface modification via plasmid-mediated pLAMA3-CM gene transfection promotes the attachment of gingival epithelial cells to titanium sheets in vitro and improves biological sealing at the transmucosal sites of titanium implants in vivo

Although titanium implants have been applied in dental clinics to replace lost teeth and to restore masticatory function for decades, strategies to design the surface of the transmucosal sites of implants to achieve ideal and predictable biological sealing following implantation remain to be optimized. In this study, we hypothesized that gingival epithelial cell (GEC) adhesion and new tissue attachment to titanium sheets/implants could be promoted by the release of plasmid pLAMA3-CM (encoding a motif of the C-terminal globular domain of LAMA3) from a titanium surface. To test this hypothesis, a chitosan/collagen (Chi/Col) coating was immobilized on the surfaces of titanium substrates with nanotube topography (NT-Ti) through cathodic electrophoretic deposition; it was found that pLAMA3-CM could be released from the coating in a highly sustained manner. After culturing on titanium with nanotube topography coated by Chi/Col with the plasmid pLAMA3-CM (Chi/Col/pLAMA3-CM-Ti), human GECs (hGECs) were found to effectively uptake the incorporated plasmids, which resulted in improved attachment, as evidenced by morphological and immunofluorescence analyses. In addition, Chi/Col/pLAMA3-CM-Ti induced better biological sealing at transmucosal sites following immediate implantation into Sprague-Dawley rats. Our findings indicate that the modification of titanium implants by plasmid-mediated pLAMA3-CM gene transfection points to a practical strategy for optimizing biological sealing around the transmucosal sites of implants.

M2 Macrophages Enhance the Cementoblastic Differentiation of Periodontal Ligament Stem Cells via the Akt and JNK Pathways

Although macrophage (Mφ) polarization has been demonstrated to play crucial roles in cellular osteogenesis across the cascade of events in periodontal regeneration, how polarized Mφ phenotypes influence the cementoblastic differentiation of periodontal ligament stem cells (PDLSCs) remains unknown. In the present study, human monocyte leukemic cells (THP-1) were induced into M0, M1, and M2 subsets, and the influences of these polarized Mφs on the cementoblastic differentiation of PDLSCs were assessed in both conditioned medium-based and Transwell-based coculture systems. Furthermore, the potential pathways and cyto-/chemokines involved in Mφ-mediated cementoblastic differentiation were screened and identified. In both systems, M2 subsets increased cementoblastic differentiation-related gene/protein expression levels in cocultured PDLSCs, induced more PDLSCs to differentiate into polygonal and square cells, and enhanced alkaline phosphatase activity in PDLSCs. Furthermore, Akt and c-Jun N-terminal Kinase (JNK) signaling was identified as a potential pathway involved in M2 Mφ-enhanced PDLSC cementoblastic differentiation, and cyto-/chemokines (interleukin (IL)-10 and vascular endothelial growth factor [VEGF]) secreted by M2 Mφs were found to be key players that promoted cell cementoblastic differentiation by activating Akt signaling. Our data indicate for the first time that Mφs are key modulators during PDLSC cementoblastic differentiation and are hence very important for the regeneration of multiple periodontal tissues, including the cementum. Although the Akt and JNK pathways are involved in M2 Mφ-enhanced cementoblastic differentiation, only the Akt pathway can be activated via a cyto-/chemokine-associated mechanism, suggesting that players other than cyto-/chemokines also participate in the M2-mediated cementoblastic differentiation of PDLSCs. Stem Cells 2019;37:1567-1580.

[The protective effects of vitamin E on lung injury caused by high temperature and PM2.5 in COPD rats]

OBJECTIVE

To investigate the effects of vitamin E on the respiratory function impairment in rats with chronic obstructive pulmonary disease (COPD) after exposed to high temperature and PM_2.5.

METHODS

Fifty-four 7-week-old SPF male Wistar rats were randomly divided into 9 experimental groups (n=6). The rat COPD model was established by lipopolysaccharide (LPS) and smoke exposure. After modeled, the rats were tracheal instilled with PM_2.5 (0 mg/ml, 3.2 mg/ml) and intraperitoneally injected with vitamin E at the dose of 40 mg/kg (20 mg/ml). Part of rats (high temperature groups) were then exposed to high temperature (40℃), once (8 h) a day for three consecutive days. After the last exposure, the lung function of rats was detected. The expression levels of inducible nitric oxide synthase (iNOS), tumor necrosis factor-α (TNF-α) and monocyte chemotactic protein-1 (MCP-1) were detected by corresponding ELISA kits.

RESULTS

Compared with the control group, exposure of high temperature and PM_2.5 could inhibit the lung function of COPD rats significantly (P＜0.05); the level of MCP-1 was increased significantly in PM_2.5-exposure groups (P＜0.05); iNOS was increased significantly in the groups of high temperature (P＜0.05). Compared with the single-PM_2.5 exposure groups, TNF-α in lung was decreased in the normal temperature health group and high temperature COPD group (P＜0.05) after treated with vitamin E; MCP-1 was decreased in all vitamin E-treated groups (P＜0.05); the decreased iNOS only appeared in the group of high temperature with vitamin E treatment.

CONCLUSION

High temperature and PM_2.5 could aggravate the inflammation of COPD rats. As an antioxidant, vitamin E may protect the lung from the damage effects.

High-order implicit particle-in-cell method for plasma simulations at solid densities

A high-order implicit multidimensional particle-in-cell (PIC) method is developed for simulating plasmas at solid densities. The space-time arrangement is based on Yee and a leapfrog algorithm for electromagnetic fields and particle advancement. The field solver algorithm completely eliminates numerical instabilities found in explicit PIC methods with relaxed time step and grid resolution. Moreover, this algorithm eliminates the numerical cooling found in the standard implicit PIC methods by using a pseudo-electric-field method. The particle pusher algorithm combines the standard Boris particle pusher with the Newton-Krylov iteration method. This algorithm increases the precision accuracy by several orders of magnitude when compared with the standard Boris particle pusher and also significantly decreases the iteration time when compared with the pure Newton-Krylov method. The code is tested with several benchmarks, including Weibel instability, and relativistic laser plasma interactions at both low and solid densities.

Particle-in-cell simulation of transport and energy deposition of intense proton beams in solid-state materials

A particle-in-cell (PIC) simulation code is used to investigate the transport and energy deposition of an intense proton beam in solid-state material. This code is able to simulate close particle interactions by using a Monte Carlo binary collision model. Such a model takes into account all related interactions between the incident protons and material particles, e.g., proton-nucleus, proton-bound-electron, and proton-free-electron collisions. This code also includes a Monte Carlo model for the collisional ionization and electron-ion recombination as well as the depression of the ionization potential by shielding of surrounding particles. Moreover, for intense proton beams, in order to include collective electromagnetic effects, significantly speed up the simulation, and simultaneously avoid numerical instabilities, an approach that combines the PIC method with a reduced model of high-density plasma based on Ohm's law is used. Simulation results indicate that the collective electromagnetic effects have a significant influence on the transport and energy deposition of proton beams. The Ohmic electric field would increase the stopping power and leads to a shortened range of proton beams in solid. The magnetic field would localize the energy deposition by collimating proton beams, which would otherwise be deflected by the collisions with nuclei.

Building capacity for macrophage modulation and stem cell recruitment in high-stiffness hydrogels for complex periodontal regeneration: Experimental studies in vitro and in rats

Recently, we found that although high-stiffness matrices stimulated osteogenic differentiation of bone marrow-derived stromal cells (BMSCs), the macrophages (Mφs) in high-stiffness transglutaminase crosslinked gelatins (TG-gels) tended to undergo M1 polarization and hence compromised cell osteogenesis. In this study, we hypothesized that the copresentation of interleukin (IL)-4 and stromal cell-derived factor (SDF)-1α in high-stiffness TG-gels may enhance periodontal regeneration by modulating Mφ polarization and promoting endogenous stem cell recruitment. We found that Mφs were more likely to polarize toward an immunomodulatory M2 state in the presence of IL-4 and hence positively influence the osteogenic differentiation of BMSCs when these cells coexisted in either indirect or direct co-culture systems. In cell migration assays, BMSCs exhibited an enhanced capability to move toward gels containing SDF-1α, and more cells could be recruited into the three-dimensional matrix of TG-gels. When TG-gels containing IL-4 and/or SDF-1α were used to repair periodontal defects, more new bone (MicroCT) was formed in animals that received the dual cytokine-loaded transplants at 4 weeks postsurgery. Mφs were recruited to all the transplanted gels, and after one week, more M1-phenotype cells were found in the groups without IL-4, while the presence of IL-4 was more likely to result in M2 polarization (immunofluorescence staining). When the tissue biopsies were histologically examined, the TG-gels containing both IL-4 and SDF-1α led to a generally satisfactory regeneration with respect to attachment recovery (epithelial and connective tissue) and hybrid tissue regeneration (bone, periodontal ligament and cementum). Our data suggest that the incorporation of IL-4 into high-stiffness TG-gels may promote the M2 polarization of Mφs and that SDF-1α can be applied to guide endogenous cell homing. Overall, building capacity for Mφ modulation and cell recruitment in high-stiffness hydrogels represents a simple and effective strategy that can support high levels of periodontal tissue regeneration. STATEMENT OF SIGNIFICANCE: The development of hydrogel-based regenerative therapies centered on the mobilization and stimulation of native cells for therapeutics opens a window toward realizing periodontal endogenous regeneration. In the present study, the parallel use of immunomodulatory and homing factors in high-stiffness hydrogel materials is shown to induce stem cell homing, modulate cell differentiation and indeed induce regrowth of the periodontium. We found that incorporation of interleukin (IL)-4 in high-stiffness TG-gels coaxed macrophages to polarize into M2 phenotypes, and stromal cell-derived factor (SDF)-1α could be applied to direct endogenous cell homing. Hence, we present for the first time a clinically relevant strategy based on macrophage modulation and host cell recruitment that can support high levels of periodontal tissue regeneration.

Modulating macrophage responses to promote tissue regeneration by changing the formulation of bone extracellular matrix from filler particles to gel bioscaffolds

Extracellular matrices (ECMs) derived from native tissues/organs have been used as biomaterials for tissue engineering and regenerative medicine in a wide range of preclinical and clinical settings. The success or failure of these applications is largely contingent on the host responses to the matrices in vivo. Despite retaining their native structural and functional proteins, bone ECM-based transplants have been reported to evoke adverse immune responses in many cases; thus, optimizing the immunomodulatory properties of bone ECMs is critical for ensuring downstream regenerative outcomes. Using a simple digestion-neutralization protocol, we transformed the commonly used bone-derived filler particles into gel bioscaffolds. Instead of inducing macrophages toward proinflammatory (M1) polarization, as reported in the literature and confirmed in the present study for ECM particles, the ECM gels were found to be more likely to polarize macrophages toward regulatory/anti-inflammatory (M2) phenotypes, leading to enhanced tissue regeneration in a rat periodontal defect model. The present work demonstrates a simple, practical and economical strategy to modify the immunomodulatory properties of bone ECMs before their in vivo transplantation and hence has important implications that may facilitate the use of ECM-based bioscaffolds derived from diverse sources of tissues for regenerative purposes.

Laser Acceleration of Highly Energetic Carbon Ions Using a Double-Layer Target Composed of Slightly Underdense Plasma and Ultrathin Foil

We report the experimental generation of highly energetic carbon ions up to 48 MeV per nucleon by shooting double-layer targets composed of well-controlled slightly underdense plasma and ultrathin foils with ultraintense femtosecond laser pulses. Particle-in-cell simulations reveal that carbon ions are ejected from the ultrathin foils due to radiation pressure and then accelerated in an enhanced sheath field established by the superponderomotive electron flow. Such a cascaded acceleration is especially suited for heavy ion acceleration with femtosecond laser pulses. The breakthrough of heavy ion energy up to many tens of MeV/u at a high repetition rate would be able to trigger significant advances in nuclear physics, high energy density physics, and medical physics.

Role of the P2X7 receptor in inflammation-mediated changes in the osteogenesis of periodontal ligament stem cells

Accumulating evidence indicates that the pluripotency of periodontal ligament stem cells (PDLSCs) is compromised under inflammatory conditions; however, the underlying mechanisms remain largely unexplored. In this study, we hypothesize that the P2X7 receptor (P2X7R) is a key molecule linked to inflammation-associated impairment of PDLSCs. We first investigated P2X7R expression in PDLSCs under normal and inflammatory conditions and then determined the effect of a P2X7R agonist (BzATP) or antagonist (BBG) on PDLSC osteogenesis under various conditions. Gene-modified PDLSCs were used to further examine the role of P2X7R and the signaling pathway underlying P2X7R-enhanced osteogenesis. We found that inflammatory conditions decreased P2X7R expression in PDLSCs and reduced osteogenesis in these cells. In addition, activation of P2X7R by BzATP or overexpression of P2X7R via gene transduction reversed the inflammation-mediated decrease in PDLSC osteogenic differentiation. When selected osteogenesis-related signaling molecules were screened, the PI3K-AKT-mTOR pathway was identified as potentially involved in P2X7R-enhanced PDLSC osteogenesis. Our data reveal a crucial role for P2X7R in PDLSC osteogenesis under inflammatory conditions, suggesting a new therapeutic target to reverse or rescue inflammation-mediated changes in PDLSCs for future mainstream therapeutic uses.

Unified decomposition method to study Rayleigh-Taylor instability in liquids and solids

In the previous studies of Rayleigh-Taylor instability, different methods were used to consider the effects of elasticity, viscosity, and magnetic fields. In this paper, a unified method, which was first used for fluids, is validated for different physical models, where the unstable mode is decomposed into an irrotational part and a rotational part, and the latter one includes the effects of nonconservative forces and constitutive relations. Previous results of solid and liquid with or without the effects of magnetic fields and finite thickness can be easily recovered after applying the corresponding interface boundary conditions. In addition, new approximate but analytical solutions of the growth rates for a semi-infinite solid-solid interface and solid-fluid interface are obtained with substantially improved accuracy in comparison with the previous ones.

First-Principles Estimation of Electronic Temperature from X-Ray Thomson Scattering Spectrum of Isochorically Heated Warm Dense Matter

Through the perturbation formula of time-dependent density functional theory broadly employed in the calculation of solids, we provide a first-principles calculation of x-ray Thomson scattering spectrum of isochorically heated aluminum foil, as considered in the experiments of Sperling et al. [Phys. Rev. Lett. 115, 115001 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.115001], where ions were constrained near their lattice positions. From the calculated spectra, we find that the electronic temperature cannot exceed 2 eV, much smaller than the previous estimation of 6 eV via the detailed balance relation. Our results may well be an indication of unique electronic properties of warm dense matter, which can be further illustrated by future experiments. The lower electronic temperature predicted partially relieves the concern on the heating of x-ray free electron laser to the sample when used in structure measurement.

Inhibition of Histone Deacetylases Attenuates Morphine Tolerance and Restores MOR Expression in the DRG of BCP Rats

The easily developed morphine tolerance in bone cancer pain (BCP) significantly hindered its clinical use. Increasing evidence suggests that histone deacetylases (HDACs) regulate analgesic tolerance subsequent to continuous opioid exposure. However, whether HDACs contribute to morphine tolerance in the pathogenesis of BCP is still unknown. In the current study, we explored the possible engagement of HDACs in morphine tolerance during the pathogenesis of BCP. After intra-tibia tumor cell inoculation (TCI), we found that the increased expression of HDACs was negatively correlated with the decreased expression of MOR in the DRG following TCI. The paw withdrawal threshold (PWT) and percentage maximum possible effects (MPEs) decreased rapidly in TCI rats when morphine was used alone. In contrast, the concomitant use of SAHA and morphine significantly elevated the PWT and MPEs of TCI rats compared to morphine alone. Additionally, we found that SAHA administration significantly elevated MOR expression in the DRG of TCI rats with or without morphine treatment. Moreover, the TCI-induced increase in the co-expression of MOR and HDAC1 in neurons was significantly decreased after SAHA administration. These results suggest that HDACs are correlated with the downregulation of MOR in the DRG during the pathogenesis of BCP. Inhibition of HDACs using SAHA can be used to attenuate morphine tolerance in BCP.