Hypoxia and inflammatory factor preconditioning enhances the immunosuppressive properties of human umbilical cord mesenchymal stem cells

BACKGROUND Mesenchymal stem cells(MSCs)have great potential for the treatment of various immune diseases due to their unique immunomodulatory properties.However,MSCs exposed to the harsh inflammatory environment of damaged tissue after intravenous transplantation cannot exert their biological effects,and therefore,their therapeutic efficacy is reduced.In this challenging context,an in vitro preconditioning method is necessary for the development of MSC-based therapies with increased immunomodulatory capacity and transplantation efficacy.AIM To determine whether hypoxia and inflammatory factor preconditioning increases the immunosuppressive properties of MSCs without affecting their biological characteristics.METHODS Umbilical cord MSCs(UC-MSCs)were pretreated with hypoxia(2%O_(2))exposure and inflammatory factors(interleukin-1β,tumor necrosis factor-α,interferon-γ)for 24 h.Flow cytometry,polymerase chain reaction,enzyme-linked immunosorbent assay and other experimental methods were used to evaluate the biological characteristics of pretreated UC-MSCs and to determine whether pretreatment affected the immunosuppressive ability of UC-MSCs in coculture with immune cells.RESULTS Pretreatment with hypoxia and inflammatory factors caused UC-MSCs to be elongated but did not affect their viability,proliferation or size.In addition,pretreatment significantly decreased the expression of coagulationrelated tissue factors but did not affect the expression of other surface markers.Similarly,mitochondrial function and integrity were retained.Although pretreatment promoted UC-MSC apoptosis and senescence,it increased the expression of genes and proteins related to immune regulation.Pretreatment increased peripheral blood mononuclear cell and natural killer(NK)cell proliferation rates and inhibited NK cell-induced toxicity to varying degrees.CONCLUSION In summary,hypoxia and inflammatory factor preconditioning led to higher immunosuppressive effects of MSCs without damaging their biological characteristics.

Prediction of low-cycle crack initiation life of powder superalloy FGH96 with inclusions based on damage mechanics

The effects of inclusions in powder superalloy FGH96 on low-cycle fatigue life were studied, and a low-cycle crack initiation life prediction model based on the theory of damage mechanics was proposed. The damage characterization parameter was proposed after the construction of damage evolution equations. Fatigue tests of the powder superalloy specimens with and without inclusion were conducted at 530 and 600 ℃, and the model verification was carried out for specimens with elliptical, semi-elliptical, polygon and strip-shaped surface/subsurface inclusion. The stress analysis was performed by finite element simulation and the predicted life was calculated. The results showed a satisfying agreement between predicted and experimental life.

Effect of Droop Phenomenon in InGaN/GaN Blue Laser Diodes on Threshold Current

Electroluminescence （EL） and temperature-dependent photolumineseenee measurements are performed to study the internal quantum efficiency droop phenomenon of blue laser diodes （LDs） before lasing. Based on the ABC mode, the EL result demonstrates that non-radiative recombination rates of LDs with threshold current densities of 4 and 6kA/cm2 are similar, while LD with threshold current density of 4kA/cm2 exhibits a smaller auger- like recombination rate compared with the one of 6kA/cm2. The internal quantum efficiency droop is more serious for LD with higher threshold current density. temperature-dependent photoluminescence is consistent The internal quantum efficiency value estimated from with EL measurements.

Arthroscopic Debridement and Synovium Resection for Inflammatory Hip Arthritis

Objective To evaluate the efficacy of arthroscopic surgery in inflammatory hip arthritis.Methods A retrospective clinical study was conducted inspecting 40 hips in 36 patients of inflammatory arthritis.There were 17 cases of ankylosing spondylitis,11 cases of rheumatoid arthritis,and 8 cases of psoriatic arthritis.The joints were irrigated and the inflamed tissues were debrided with anthroscopy.The patients were followed up with Harris hip score,Oxford hip score,Visual Analog Scale(VAS),and magnetic resonance imaging(MRI).Statistical analysis was performed using Student t test.Results All of the 36 cases were followed up for 46-103 months,averaging 67.2±8.4 months.Harris and Oxford scores increased from 66.9±12.1 and 69.4±16.4 before operation to 78.4±19.3 and 80.2±18.8 after operation,respectively(P<0.05).VAS score decreased from pre-operative 8.5±2.5 to post-operative 7.2±2.5(P<0.05).All the patients showed improved joint range of motion.MRI revealed alleviation of hip synovitis.The results were classified as excellent in 8 patients,good in 17 patients,fair in 8 patient,and poor in 3 according to Harris hip score.Twenty-seven patients were satisfied with the operative outcomes as they regained normal daily activities.Conclusions Arthroscopy-assisted joint debridement and synovium resection is an effective procedure for hip lesion in inflammatory arthritis.The inflammatory lesion might be thereby controlled and the symptoms be relieved.

Microstructure and interfacial strength of SiC fiber-reinforced Ti17 alloy composites with different consolidation temperatures

The interfacial reaction and titanium matrix microstructure in continuous SiC fiber-reinforced titanium matrix composite were investigated. By comparison of two samples actuated by 800 ℃ （in α ＋ β dual-phase field） and 920 ℃ （in 13 single-phase field） consolidation, it can be concluded that tri-layer interfacial reaction regions con- sisting of fine TiCx/transition TiCx/coarse TiCx are formed in both two samples. In addition, the total thickness of reaction layer for composites prepared at 920℃ is thicker than that consolidated at 800℃, while fine TiCx layer of 920℃ sample is thinner than that of 800 ℃ sample, which may be ascribed to the quick growth of PVD-Ti17 grain manufactured at 920 ℃. In addition, lower interfacial shear strength is obtained in 920 ℃ sample, which can be ascribed to the formation of too thick brittle TiC layer. The research in the work is expected to motivate further exploration for interface adjustment of titanium matrix composites.

Effect of increased nitrogen content on continuous cooling transition of γ→α in hot-deformed low-C Mo-V-Ti steels

The two-stage controlled rolling and cooling at 0.5-50℃/s of low-carbon Mo-V-Ti steels with the increasing nitrogen content from 0.0032 to 0.0081 and 0.0123 wt.% were simulated through a Gleeble 3500 system. The continuous cooling transition (CCT) of γ→α in each steel was estimated via microstructure characterization and CCT diagram. The results indicated that CCT diagram for each steel was divided into three regions of γ→ferrite,γ→pearlite and γ→ bainite, and the increasing N content elevated all the starting temperatures for γ→α. Consequently, the polygonal ferrite (PF) and pearlite formed in each steel cooled at 1℃/s and, however, the increasing N content led to slightly coarser ferrite grain and pearlite colony. With the increased cooling rate to 10 and 30℃/s, a mixed microstructure of acicular ferrite (AF), granular bainite (GB) and lath bainite (LB) formed in 32N steel and in contrast, the mixture of PF+AF+GB in 8IN and 123N steels. The increasing N content promoted (Ti,V)(C,N) precipitation, enhanced the intragranular PF/AF nucleation, increased martensite/austenite constituent and depressed LB. In addition, the mechanisms dominating the effect of increasing N on this CCT of γ→α were discussed.

Zinc(Ⅱ) coordination architectures based on 5-(1H-tetrazol-1-yl)-isophthalic acid:Synthesis,structures and luminescent properties

With different pyridine-analogs as auxiliary ligands,three novel Zn（Ⅱ） complexes（1-3） based on 5-（1Htetrazol-1-yl） isophthalic acid（H_2L） have been synthesized and structurally characterized.Single crystal X-ray diffraction analyses of complexes 1-3 show the presence of tetrazolyl group,as well as the coordination behavior of the auxiliary ligands as critical factors determining the structures of such Zn（Ⅱ）-carboxyIate coordination architectures.In addition,the resulting complexes all exhibit luminescence properties in the solid state at room temperature.