Pathologically Elevated-Cyclic Stretch Suppressed Vascular Smooth Muscle Cell Mitochondrial Biogenesis by Down-regulating PGC1α Expression / 医用生物力学

Objective To investigate the effect of pathologically elevated-cyclic stretch induced by hypertension on mitochondrial biogenesis of vascular smooth muscle cells (VSMCs), and the role of PGC1α in this process. Methods The Flexcell-5000T stretch loading system in vitro was applied to VSMCs with a frequency of 1. 25 Hz and an amplitude of 5% or 15% to simulate the mechanical environment under normal physiological or hypertensive pathological conditions respectively. Western blotting and qPCR were used to detect the expression of PGC1α, citrate synthase and mitochondrial DNA (mtDNA) copy number in VSMCs under normal physiological or hypertensive pathological conditions. VSMCs were treated with PGC1α specific activator ZLN005 to promote PGC1α expression or specific interfering fragment siRNA to inhibit PGC1α expression in order to detect the effect on citrate synthase and mtDNA copy number. Results Compared with 5% physiological cyclic stretch, 15% pathologically elevated-cyclic stretch significantly suppressed the expression of PGC1α, citrate synthase and mtDNA copy number in VSMCs. Compared with control group, the protein expression of PGC1α was significantly decreased and increased respectively. When VSMCs transfected with PGC1α siRNA or incubated PGC1α activator ZLN005, the expression of citrate synthase and mtDNA copy number were also significantly down regulated and up-regulated in VSMCs accordingly. Under physiological cyclic stretch conditions, the protein level of PGC1α was significantly down-regulated by PGC1α siRNA, which also significantly down-regulated citrate synthase expression and mtDNA copy number. The protein expression of PGC1α was significantly up-regulated by ZLN005, which also enhanced the expression of citrate synthase and mtDNA copy number. Conclusions The pathological cyclic stretch induced by hypertension significantly down-regulated the expression of citrate synthase and mtDNA copy number via suppressing the expression of PGC1α, resulting in mitochondrial dysfunction of VSMCs. PGC1α may be a potential therapeutic target molecule to alleviate the progression of hypertension.

Inhibitory Effect of Paeonol on Vascular Smooth Muscle Cell Senescence by Reducing SIRT6/PARP1-mediated DNA Damage / 中国实验方剂学杂志

ObjectiveTo investigate whether the effects of paeonol （Pae） on angiotensin Ⅱ （AngⅡ）-induced senescence in vascular smooth muscle cells （VSMCs） were related to angiotensinogen of silencing regulatory information factor 6 （SIRT6）/adenosine diphosphate ribose polymerase 1 （PARP1） signaling pathway in VSMCs. MethodThe model of VSMC-stress aging induced by AngⅡ （100 nmol·L-1） was established. The rats were divided into normal group， model group， low， medium， and high-concentration Pae groups （30， 60， 120 μmol·L-1）. The positive rate of cell senescence was detected by SA-β-Gal staining， the ability of cell proliferation was detected by the cell counting kit-8 （CCK-8） method， the expression of SIRT6， PARP1， p16， p21， p53， proliferating cell nuclear antigen （PCNA）， deoxyribonucleic acid （DNA）-damaged protein γ-H2AX was detected by Western blot， and VSMC proliferation was detected by EdU staining. The silenced VSMCs were prepared by siRNA-SIRT6 transfection， and the protein expressions of SIRT6， PARP1， p16， and γ-H2AX in VSMCs silenced by SIRT6 were observed. ResultThe results of SA-β-Gal staining showed that the senescence positive rate of SA-β-Gal staining in the model group was higher than that in the normal group （P<0.01）， and the positive rate of SA-β-Gal staining in the Pae group was significantly lower than that in the model group （P<0.05， P<0.01）. The results of Western blot showed that as compared with the normal group， the expression of PCNA， SIRT6， and PARP1 in the model group was down-regulated， and the expression of aging-related proteins p16， p21， p53， and γ-H2AX was up-regulated in the model group （P<0.05， P<0.01）. Compared with the model group， Pae promoted the protein expression of PCNA， SIRT6， and PARP1 and inhibited the protein expression of p16， p21， p53， and γ-H2AX in a dose-dependent manner （P<0.05， P<0.01）. The results of EdU staining showed that the number of EdU positive cells in the model group was lower than that in the normal group （P<0.01）， and the number of EdU positive cells in Pae groups was significantly higher than that in the model group （P<0.05， P<0.01）. After SIRT6 silencing， the effects of Pae on promoting SIRT6 and PARP1 and inhibiting P16 were reversed （P<0.05， P<0.01）. In addition， the addition of SIRT6 inhibitor （IN-1） promoted the occurrence of cell senescence induced by AngⅡ （P<0.05， P<0.01）. ConclusionPae can effectively inhibit the aging of VSMCs， and its mechanism may be related to the regulation of SIRT6/PARP1 signal pathway.

Src/RUNX2 Modulates the Migration of Vascular Smooth Muscle Cells Induced by Cyclic Stretch / 医用生物力学

Objective To investigate the effect of cyclic stretch on Src and Runt-related transcription factor 2 (RUNX2), and their pivotal roles in migration of vascular smooth muscle cells (VSMCs). Methods The 5% cyclic stretch (to simulate normotensive physiological condition) or 15% cyclic stretch (to simulate hypertensive pathological condition) was applied to VSMCs by FX-5000T system. Western blotting was used to detect the expression of RUNX2 and phosphorylation of Src in VSMCs. The Ingenuity Pathway Analysis (IPA) bioinformatic software was used to analyze the potential regulatory effect of Src on RUNX2. Small interfering RNA (siRNA) was transfected to decrease the expression of RUNX2. Src inhibitor-1 was used to repress Src kinase activity; Wound-healing assay was applied to detect VSMC migration. Results Compared with 5% cyclic stretch, 15% cyclic stretch significantly increased RUNX2 expression in VSMCs. Under both static and 15% cyclic stretch conditions, VSMC migration was significantly inhibited after reducing RUNX2 expression with siRNA transfection. IPA indicated that Src kinase might be the upstream modulator of RUNX2, and Western blotting validated that RUNX2 expression was significantly decreased after inhibiting Src. Furthermore, under 15% cyclic stretch, Src inhibitor-1 markedly repressed RUNX2 expression and VSMC migration.Conclusions High cyclic stretch increased phosphorylation of Src kinase and expression of RUNX2, which subsequently induced VSMC abnormal migration. Exploring the mechanobiological mechanism of VSMC migration regulated by cyclic stretch may contribute to further revealing the mechanism of vascular physiological homeostasis and vascular pathological remodeling, as well as providing new perspective for the translational research of vascular remodeling upon hypertension.

Physiological Cyclic Stretch Inhibits Vascular Smooth Muscle Cell Migration via Activating AMPK Phosphorylation / 医用生物力学

Objective To explore the role of adenosine monophosphate-activated protein kinase (AMPK), a key regulator of cellular energy metabolism, in vascular smooth muscle cell (VSMC) migration in response to physiological cyclic stretch. Methods The Flexcell-5000T mechanical loading system was applied with a physiological cyclic stretch at 10% amplitude and 1.25 Hz frequency to primary rat VSMCs, to simulate mechanical stimulation of VSMCs in vivo. The protein expression of p-AMPK in VSMCs was detected by Western blotting, and VSMC migration was detected by wound healing test. Results Compared with the static group, physiological cyclic stretch loading for 24 h significantly decreased the area of wound healing, indicating that physiological cyclic stretch inhibited VSMC migration. The protein expression of p-AMPK in VSMCs was increased significantly after physiological cyclic stretch loading for 3 h, and was decreased significantly after 24 h. Under physiological cyclic stretch loading conditions, incubating AMPK inhibitor could significantly reduce the protein expression of p-AMPK after 3 h, and promote VSMC migration after 24 h; incubating AMPK activator AICAR under static conditions significantly increased the protein expression of p-AMPK after 3 h, and weakened VSMC migration after 24 h. Conclusions Physiological cyclic stretch inhibits VSMC migration by increasing the protein expression of p-AMPK, indicating that VSMC migration regulated by physiological cyclic stretch is of great significance for maintaining vascular homeostasis.

Calcium Participates in Migration of VSMCS Synergistically Induced by Cyclic Stretch and Platelet-Derived Microvesicles / 医用生物力学

Objective To investigate the synergistic effects of pathologically elevated cyclic stretch and platelet-derived microvesicles (PMVs) on migration of vascular smooth muscle cells (VSMCs) and the potential role of calcium in this process. Methods The FX-5000T strain loading system was used to apply cyclic stretch to VSMCs with magnitudes of 5% and 15%, which simulated physiological and hypertensive situation respectively in vitro; wound healing assay was used to analyze VSMCs migration; Ca2+-free medium was used to remove extracellular calcium; 2-APB (an antagonist of IP3R) was used to inhibit the release of intercellular stored calcium; GSK219 (an antagonist of TRPV4) and Nifedipine (an inhibitor of L-type voltage-gated calcium channel) were applied to block the activity of respective calcium channel; thrombin was used to stimulate platelets in vitro which simulated the hypertensive activation of PMVs in vivo. ResultsCompared with 5% cyclic stretch, 15% cyclic stretch significantly promoted VSMC migration. Removal of extracellular calcium inhibited VSMCs migration, but the application of GSK219 and Nifedipine did not affect the migration up-regulated by 15% cyclic stretch; while 2-APB which inhibited the release of intracellular stored calcium could also repress VSMCs migration under 15% cyclic stretch. PMVs further promoted VSMC migration under 15% cyclic stretch condition, and both extracellular calcium and intercellular stored calcium were involved in this process. Conclusions Both intracellular and extracellular calcium play important roles in VSMC migration induced by 15% cyclic stretch, and PMVs synergistically participate in the above process. The study is aimed to provide new mechanobiological insights into the molecular mechanism and clinical targets of vascular remodeling in hypertension.

Inhibitory mechanism of icariin against oxidative stress-induced calcification in aortic vascular smooth muscle cells / 中国中药杂志

This study aimed to observe the inhibitory effect of icariin against oxidative stress-induced calcification in aortic vascular smooth muscle cells(VSMCs) and elucidate the molecular mechanism of icariin in inhibiting endoplasmic reticulum stress(ERS)-mediated atherosclerotic calcification, so as to provide new ideas for exploring the anti-atherosclerotic mechanism of Epimedii Folium. The VSMCs in rat thoracic aorta were subjected to adherent culture and then treated with the complete calcification DMEM containing high glucose and hydrogen peroxide(H_2O_2) for three weeks. The resulting calcified VSMCs were divided into different treatment groups. Icariin was added one week after calcification induction for protecting the VSMCs, whose viability was then detected using cell counting kit-8(CCK-8). Alizarin red-S staining was conducted to observe the calcification degree. The activity of alkaline phosphatase(ALP) in VSMCs was measured using the disodium phenyl phosphate substrate and the calcium content was measured by arsenazo Ⅲ method. The mRNA expression levels of ossification-related factors including osteocalcin(OC), osteopontin(OPN), Runt-related transcription factor 2(Runx2), and type Ⅰ collagen(Col Ⅰa) were detected by real-time PCR. Western blot was carried out to determine the protein expression levels of α-smooth muscle actin(α-SMA), Runx2, activating transcription factor 4(ATF4), and eukaryotic translation initiation factor(eIF)-2α. The results showed that H_2O_2 significantly induced the calcification of VSMCs, increased the ALP activity and calcium content in VSMCs, promoted OC, OPN, Runx2, and Col Ⅰa mRNA expression and Runx2 protein expression, and reduced α-SMA protein expression. The ATF4 protein expression and eIF2α phosphorylation were also elevated significantly. Icariin reversed the calcification of VSMCs induced by H_2O_2, inhibited ALP activity and calcium content in VSMCs, down-regulated the mRNA expression levels of OC, OPN, Runx2 and Col Ⅰa and Runx2 protein expression, and relatively up-regulated the expression of α-SMA. The expression of ATF4 and phosphorylation of eIF2α also declined significantly. All these have demonstrated that icariin inhibited VSMCs calcification by down-regulating the ossification-related factors and lowering ALP activity and calcium content in VSMCs. Besides, the down-regulation of Runx2 expression and the inhibition of ATF4 and eIF2α-mediated cellular calcification pathway in ERS might also be involved in such calcification-suppressing process.

Cyclic Stretch Induces Adhesion of VSMCs with Platelet-Derived Microparticles and the Role in Autophagy / 医用生物力学

Objective To investigate the effect of cyclic stretch on adhesion of vascular smooth muscle cells (VSMCs) with platelet-derived microparticles (PMPs), and the role of PMPs in VSMC autophagy. Methods Cyclic stretch with the magnitude of 5% (simulating physiological mechanical stretch) or 15% (simulating pathological mechanical stretch) was subjected to VSMCs in vitro by using FX-5000T cyclic stretch loading system, and the adhesion of PMPs in VSMCs was detected by using flow cytometry. Immunofluorescence was used to detect the expression of autophagy microtubule associated protein light chain 3 (LC3) after 24 h stimulation with PMPs. Western blotting was used to detect the expression of autophagy related protein (Atg) in VSMCs after 24 h stimulation by PMPs. Results Compared with 5% cyclic stretch, 15% cyclic stretch significantly increased the adhesion ability of VSMCs with PMPs. Immunofluorescence and Western blotting result revealed that PMPs stimulation significantly increased the expression of autophagy marker protein LC3 in VSMCs. Furthermore, the protein expressions of Atg5, Atg7 and Atg12 were all significantly increased in VSMCs stimulated with PMPs. Conclusions High cyclic stretch may enhance the autophagy of VSMCs by promoting the adhesion of PMPs, which will subsequently increase the expressions of Atg5, Atg7, Atg12 and LC3.

Physiological Cyclic Stretch Inhibits Vascular Smooth Muscle Cell Apoptosis via Inducing Expression of Nuclear Envelope Protein Emerin / 医用生物力学

Objective To investigate the mechanical response of Emerin, a nuclear envelope protein, and its role in apoptosis of vascular smooth muscle cells (VSMCs) during cyclic stretch, and the potential effect of transcriptional factors in this process. Methods Physiological cyclic stretch with the magnitude of 5% and frequency of 1.25 Hz was subjected to VSMCs in vitro by using FX-5000T cyclic stretch loading system. VSMCs cultured under the same conditions but without applying mechanical stretch were used as the static control. The apoptosis of VSMCs was detected by using Cleaved-caspase3 ELISA kit, and the expression of Emerin was revealed by using Western blotting. The effects of Emerin on activities of 345 kinds of transcriptional factors in VSMCs were demonstrated with Protein/DNA array after Emerin specific RNA interference (RNAi) under static condition, and the potential transcriptional factors involved in VSMC apoptosis were analyzed with Ingenurity Pathway Analysis (IPA) software. Furthermore, the binding abilities of Emerin to the motif of 2 kinds of apoptosis-related transcriptional factors were detected with chromatin immunoprecipitation (CHIP) and qPCR. ResultsCompared with the static control, the apoptosis of VSMCs was significantly decreased by 5% cyclic stretch, which suggested a protective effect of physiological cyclic stretch. The expressions of Emerin in VSMCs was remarkably increased with 5% cyclic stretch applied for 6 h, 12 h and 24 h. Specific RNAi under static condition decreased the expressions of Emerin but increased the apoptosis of VSMCs. Emerin siRNA transfection remarkably increased (more than 2 times) the activities of 10 transcriptional factors that participated in cellular apoptosis, i.e. CREB-BP1, p300, p55, MAX, NRF-1, STAT1, STAT3, TEF1, TR and BZP. CHIP-qPCR result revealed that the binding ability of Emerin to specific mofit of STAT1 or STAT3 was significantly repressed with Emerin RNAi. Conclusions Physiological cyclic stretch could increase the expression of Emerin which might modulate the binding of Emerin to motifs of apoptosis-related transcriptional factors such as STAT1 and STAT3, regulate the activities of these factors, and then subsequently repress the VSMC apoptosis. The investigation on mechanobiological mechanisms of VSMC apoptosis induced by cyclic stretch may contribute to further understanding the physiological and pathological mechanisms of vascular homeostasis and vascular remodeling.

Farrerol inhibits AngII-induced VSMCs proliferation by reducing Cx43 expression / 中国药理学通报

Aim To study the role of Cx43 in inhibi-tion of AngII-induced vascular smooth muscle cells(VSMCs) proliferation by farrerol. Methods The primary VSMCs were isolated and cultured by direct adherent culture methods. VSMCs were identified by immunohistochemstry. The cells were divided into the following groups:control group,AngII group,AngII+Farrerol group. The cell viability was measured by CCK-8 cell vitality test. The proliferation of VSMCs was measured by the methods of Edu. The cell cycle of VSMCs was detected by flow cytometry. The mRNA levels of Cx43 were measured by Real-time PCR. The protein levels of Cx43 were measured by Western blot. Results 60 μmol·L-1farrerol could significantly de-crease the cell viability and EdU rate of VSMCs in-duced by AngII(P<0.05),which could also prevent the transformation of VSMCs from G0/G1phase to S phase. The results of real-time PCR and Western blot showed that,compared with the model group,Farrerol could significantly reduce the mRNA and protein ex-pression level of Cx43(P <0.01). After the interfer-ence of Cx43 by siRNA, the inhibition of proliferation by farrerol decreased significantly. Conclusion Far-rerol inhibits AngII-induced VSMCs proliferation signif-icantly, which might be associated with reducing the expression of Cx43.

Rosuvastatin inhibits homocysteine-induced smooth muscle cell phenotype transformation and its signal pathway / 西安交通大学学报(医学版)

ABSTRACT:Objective To verify whether rosuvastatin can inhibit homocysteine (Hcy)‐induced rat aortic vascular smooth muscle cell (VSMC ) phenotype transformation and its potential mechanism .Methods The primary culture and identification of rat VSMCs were conducted , using VSMCs in passage4‐7 for the following experiments .The VSMCs were divided into 4 groups:control group ,Hcy (100μmol/L) group ,Hcy+ rosuvastatin group ,and Hcy+ rapamycin group .MTT was used to investigate the proliferation of VSMCs .Transwell chambers and wound healing were employed to test the migration ability of VSMCs . ICC was used to detect the VSMCs'morphology .Western blotting was used to investigate the expressions of SM‐actin ,SM‐MHC ,calponin ,OPN ,and p‐P70S6K1 in VSMCs of each group .Results Compared with those in control group , the proliferation and migration ability of VSMCs were significantly increased in Hcy modulation group (P< 0 .01) .The expressions of SM‐MCH and calponin increased but those of OPN and p‐P70S6K1 decreased in Hcy group compared with control group (P<0 .01) .The expression of SM‐actin did not significantly differ between the groups .Compared with those in Hcy modulation group , the proliferation and migration ability of VSMCs were significantly decreased in rosuvastatin and rapamycin groups ( P<0 .01) .The expressions of SM‐MCH and calponin increased while OPN and p‐P70S6K1 expressions decreased in rosuvastatin and rapamycin groups compared with Hcy group ( P< 0 .01 ) . Conclusion Hcy can induce the dedifferentiation of VSMCs ,and rosuvastatin can inhibit this effect of Hcy .Its potential mechanism may be realized via the mTOR/P70S6K1 signal pathway .

Curcumin inhibits AngⅡ-induced proliferation and oxidative stress in vascular smooth muscle cells / 西安交通大学学报(医学版)

Objective To investigate the effect of curcumin (Cur)on AngⅡ-induced proliferation and oxidative stress of vascular smooth muscle cells (VSMCs).Methods Primary rat VSMCs were cultured and divided into control group,AngⅡ group,AngⅡ+Cur 5μmol/L group,AngⅡ+Cur 10μmol/L group,AngⅡ+Cur 20μmol/L group,and Cur 20μmol/L group.The proliferation of AngⅡ-induced VSMCs was measured by MTT assay.The mRNA and protein expressions of inducible nitric oxide synthase (iNOS)and p47phox were detected by real-time PCR and Western blot.Nitric oxide (NO)production was measured by Griess reaction.Production of intracellular reactive oxygen species (ROS)was measured by DCFH-DA staining,and the activities of superoxide dismutase (SOD)and glutathione peroxidase (Gpx)were detected by xanthine oxidase assay and visible spectrophotometer. small interfering RNA (siRNA)was used to silence the expression of p47phox to further explore the mechanism for Cur inhibiting the proliferation of AngⅡ-induced VSMCs and oxidative stress.Results VSMCs activities were not significantly affected by Cur at the concentration between 0 and 80μmol/L.Cur (5,10 and 20μmol/L)significantly inhibited AngⅡ-induced proliferation of VSMCs.Cur had an inhibitory effect on the overexpression of NO,iNOS, p47phox and ROS in VSMCs and upregulated the activities of SOD and Gpx in a concentration-dependent manner. AngⅡ-induced ROS production in VSMCs was significantly attenuated by pretreatment with p47phox specific siRNA.Conclusion Cur can inhibit the proliferation and oxidative stress of AngⅡ-induced VSMCs.

Effect of block of AGEs-RAGE pathway on the migration of VSMCs / 中国药科大学学报

@#To investigate the effect of block of AGEs-RAGE pathway on the migration of aortic vascular smooth muscle in diabetic rats and its possible mechanisms, vascular smooth muscle cells(VSMCs)cells were pre-stimulated by antibody of RAGE, and then stimulated by AGEs. Transwell assay was adopted to assay migration of VSMCs. Proliferation of VSMCs and expression of p27 were analyzed by MTT and ELISA, respectively. The change of ROS level in VSMCs was defermined by DCFH assay, the expression of NOX1 mRNA was determined by RT-PCR assay. Results indicated that the AGEs induction for migration of VSMCs was significantly inhibited after treatment by RAGE antibody(P< 0. 01), which blocked the AGEs-RAGE pathway, and the inhibition of migration was stronger than that of proliferation. The ROS level was decreased(P< 0. 01), and the expression of NOX1 mRNA was decreased, yet the expression of P27 protein was not changed greatly. Block of AGEs-RAGE pathway by antibody of RAGE can inhibit the migration of VSMCs, and the mechanism may be related with the decrease of NOX1 mRNA and then down to the level of intracellular oxidative stress in VSMCs.

The role of microRNA-34a in low shear stress- induced proliferation of vascular smooth muscle cells / 医用生物力学

Objective To investigate the role of microRNA-34a (miR-34a) in the proliferation of vascular smooth muscle cells (VSMCs) induced by low shear stress (LowSS). Methods Using co-culture parallel plate flow chamber system, endothelial cells (ECs) and VSMCs were co-cultured and applied with normal shear stress (1.5 Pa) and LowSS (0.5 Pa) for 12 h. The expression of proliferating cell nuclear antigen (PCNA) in the co-cultured VSMCs was detected by Western blotting to determine the proliferation capacity of VSMCs. Real-time PCR was used to examine the miR levels of miR-34a in the co-cultured VSMCs. The target proteins of miR-34a were predicted by TargetScan, miRWalk and some other websites. Western blotting was used to detect expression of Forkhead box j2 (Foxj2) in the co-cultured VSMCs. Mimics and inhibitor were used to up-regulate or inhibit the expression of miR-34a, and then the expression of Foxj2 and PCNA was detected by Western blotting to verify the regulation relationship between miR 34a and Foxj2. Results Compared with NSS, LowSS promoted the PCNA expression and significantly up-regulated the miR-34a expression in the co-cultured VSMCs. Foxj2 was predicted to be the downstream target protein of miR-34a by TargetScan, miRWalk and some other websites. Foxj2 expression decreased significantly in the co-cultured VSMCs under LowSS application. Under static condition, the expression of Foxj2 obviously decreased and the expression of PCNA obviously increased by up-regulating miR-34a expression in VSMCs. While inhibiting the expression of miR-34a in VSMCs would result in a significant increase in the expression of Foxj2 and a significant decrease in the expression of PCNA. Conclusions LowSS can promote the proliferation of VSMCs by regulating miR-34a and target protein Foxj2 in the co-cultured VSMCs. This research finding will provide new mechanobiological experimental reference for further illustrating the pathogenesis of atherosclerosis and finding the therapeutic targets for drugs.

Regulating effect of microRNA-21 on the expression of extracellular matrix of vascular smooth muscle cells under vascular remodeling of hypertension / 医用生物力学

Objective To investigate the regulating effect and mechanism of microRNA-21 (miR-21) on extracellular matrix (ECM) of vascular smooth muscle cells (VSMCs) by vascular remodeling of hypertension. Methods By narrowing the abdominal aorta in rats, the hypertension models were established and divided into 2-week hypertension group and 4-week hypertension group, and sham-operated group was also established as control. VSMCs from the rat aorta were subjected to 0% (static), 5% (normal) and 15%（hypertensive）elongation strain at a constant frequency of 1.25 Hz and duration of 12 hours, respectively. The expressions of Smad 7 and ECM were detected by Western blotting, and the expression of miR-21 was examined by Real-time RT-PCR. Finally, miR-21 siRNA was used to study the role of miR-21 in the mechanical strain-induced expression of ECM, miR-21 and Smad 7. Results Compared with the sham-operated group, ECM and miR-21 in thoracic aorta of 2-week hypertension group were significantly elevated. Collagen I, collagen III and miR-21 in thoracic aorta of 4-week hypertension group were significantly elevated. Compared with the static and 5% strain groups, the protein expression of collagen I in VSMCs did not show significant change, but the protein expression of collagen III was significantly elevated and Smad 7 expression was significantly decreased in 15% strain group. The cyclic strain also enhanced miR-21 expression in VSMCs. miR-21 inhibitor effectively decreased the expression of miR-21 in VSMCs and protein level of collagen III, while enhanced Smad 7 expression under the static and 15% strain. Conclusions The vascular remodeling of hypertension causes the high expressions of ECM and miR-21. The cyclic strain induces the high expression of miR-21, which via Smad 7 results in enhancing the expression of ECM, collagen III especially, in VSMCs under vascular remodeling of hypertension.

Effect of chitosan on vascular smooth muscle cells inhibiting proliferation from rabbit arteriovenous fistula and its mechanisms / 中华显微外科杂志

Objective To explore the effect of chitosan on vascular smooth muscle cells inhibited proliferation from rabbit arteriovenous fistula and its mechanisms.Methods Established rabbit fistula model on carotid arteryinternal jugular vein.After 1 month cultured VSMCs with primary culture by tissue-pieces inoculation.Cultured VSMCs were divided into three groups:①normal control group.②FBS-treated group:cell were treated with 5％,10％,20％ for 48 h,respectively; established the model of rabbit VSMCs proliferation.③chitosan-treated group:VSMCs cultured with 20％ FBS were exposed to different doses of chitosan(10,100,500,1000,2000μg/ml) for 48 h.And VSMCs were treated for different time (0,12,24,48 h) with Chitosan 1000 μg/ml.Expression levels of PCNA and TLR4/ NF-κB were detected by Western blotting.RT-PCR were applied to measure the mRNA expression of PCNA and TLR4.The protein levels of TLR4 and NF-κB were detected by immunofluorescence.Results Compared with low concentration serum group,FBS-treated VSMCs exhibited a increase in mRNA and protein expression of PCNA and TLR4.FBS-induced protein expression of PCNA and TLR4/NF-κB were reduced by chitosan.Also mRNA expression of PCNA and TLR4 were reduced.They were dependent on concentration and time.In rabbit VSMCs TLR4 was mainly expressed in the cytoplasm and NF-κB expressed mainly in the nucleus.Compared with normal control group,TLR4 and NF-κB protein expression were significantly decreased by chitosan.Conclusion High concentration serum induced VSMCs proliferation.Chitosan can inhibit the proliferation of rabbit VSMCs.It is speculated that the mechanism may be related to the expression of TLR4 receptor activation,reducing expression of downstream factor MyD88 and NF-κB.It is suggest that chitosan can become potential new drugs of arteriovenous fistula prevention of intimal hyperplasia.

The role of Rab28 and ERK in low shear stress induced migration of vascular smooth muscle cells / 医用生物力学

Objective To study the role of abnormally changed migration of vascular smooth muscle cells (VSMCs) induced by low shear stress (LowSS) in vascular remodeling during atherosclerosis as well as the molecular mechanism involved in this process. Methods By using comparative proteomic analysis with two-dimensional electrophoresis combined with mass spectrometry, differential protein expression profiles of cultured vascular tissues under normal shear stress (NSS) (1.5 Pa) and LowSS (0.5 Pa) were studied. Using endothelial cells (ECs) and VSMCs co-cultured parallel plate flow chamber system, two levels of shear stress i.e. LowSS and NSS, were applied, respectively. Western blot was used to detect the protein expressions of Rab28 and phosphor-ERK. Transwell system was used to detect the migration ability of VSMCs. After using RNA interference and ERK inhibitor PD98059 to decrease the expressions of Rab28 and phosphor-ERK, respectively, the migration ability of VSMCs was observed again. Results The expression of Rab28 in the cultured rat aorta was significantly up-regulated by the LowSS (0.5 Pa) application in comparison with the NSS (1.5 Pa). The migration, expressions of Rab28, and phosphorylation of ERK in VSMCs were significantly increased by the LowSS application. Target RNA interference of Rab28 significantly decreased the migration of VSMCs, but had no specific effect on the phosphorylation of ERK. Target inhibitor of ERK, PD98059, significantly decreased both the migration and Rab28 expression in VSMCs. Conclusions The LowSS may increase the phosphorylation of ERK and then increase the expression of Rab28 in VSMCs, which subsequently modulate VSMC migration during vascular remodeling. The investigation on the role of Rab28 and its signal path in LowSS-regulated VSMCs as well as the molecular mechanism might provide a biomechanical reference for understanding the pathogenesis of vascular remodeling during atherosclerosis and finding the therapeutic target of new drugs.

The role of FOXO1 in cyclic stretch induced-proliferation of vascular smooth muscle cells during hypertension / 医用生物力学

Objective To investigate the role of pathologically increased-cyclic stretch in proliferation of vascular smooth muscle cells (VSMCs) during hypertension, and the effect of Forkhead box protein O1 (FOXO1) during this process. Methods Coarctation of abdominal aorta above kidney artery of rat was used as hypertensive animal model, and sham-operated animal as control. FX-4000 cyclic stretch loading system was used to apply 5% physiologically cyclic stretch and 15% pathologically cyclic stretch during hypertension on VSMCs in vitro. Western blot was used to reveal the expressions of FOXO1 and phosphor-FOXO1 in VSMCs, and BrdU kit to detect the proliferation of VSMCs in vitro. By using RNA interference in static, the role of FOXO1 on cell proliferation was further detected. Results After abdominal aorta coarctation for 2 and 4 weeks, respectively, the blood pressure was significantly increased compared with the sham operated rats. The proliferation of vascular cells in aorta of hypertensive rat was significantly increased, and so did the expressions of FOXO1 and phosphor-FOXO1. In vitro experiment revealed that 15% cyclic stretch remarkably increased the proliferation and expressions of FOXO1 and phospho FOXO1 in VSMCs. Target siRNA transfection in static decreased the expression of FOXO1 and phosphor-FOXO1, as well as the proliferation of VSMCs. Conclusions Pathologically increased-cyclic stretch may increase the expression and phosphorylation of FOXO1, subsequently modulate VSMC proliferation during hypertension. Based on animal models, this study intends to reveal the role of FOXO1 in vascular reconstruction of hypertension and the involved biomechanical mechanism, so as to make the mechanobiological mechanism of hypertension explicit and discover new target in the prevention and treatment of vascular remodeling.

Shear stress modulates the proliferation of vascular smooth muscle cells via receptor for activated C kinase 1 / 医用生物力学

Objective To investigate the role of receptor for activated C kinase 1 (RACK1) in vascular smooth muscle cells (VSMCs) proliferation modulated by co-cultured endothelial cells (ECs) and shear stress. Methods Using EC/VSMC co-cultured parallel plate flow chamber system, two levels of shear stress, i.e. low shear stress (LowSS, 0.5 Pa) and normal shear stress (NSS, 1.5 Pa), were applied for 12 h. BrdU ELISA was used to detect the proliferation of VSMCs, and Western blot was used to detect the protein expressions of RACK1 and phosphor-Akt. Under the static condition, RNA interference was used to suppress the expression of RACK1 in VSMCs, and then the proliferation of VSMCs and expressions of RACK1 and phosphor-Akt were detected. By using co-culture model (ECs/VSMCs) and separated culture model (ECs//VSMCs), the effect of ECs on expressions of RACK1 and phosphor-Akt in VSMCs was further analyzed. Results Comparative proteomic analysis revealed that LowSS increased the expression of RACK1 in rat aorta. In vitro experiments showed that LowSS induced the proliferation, expressions of RACK1 and phospho Akt in VSMCs co-cultured with ECs. Target RNA interference of RACK1 significantly decreased the proliferation of VSMCs, and the phosphorylation of Akt. In comparison with ECs//VSMCs (separated culture) group, the expression of RACK1 and phosphor-Akt were both up-regulated in the VSMCs co-cultured with ECs (ECs/VSMCs group). Conclusions The expression of RACK1 in VSMCs was modulated by shear stress and neighboring ECs, which might induce cellular proliferation via PI3K/Akt pathway. The investigation on VSMC proliferation and the involved biomechanical mechanism will contribute to understanding and help preventing the pathogenesis and progress of atherosclerosis.

Effect from different pore sizes of co-culture inserts on the permeability of platelet derived growth factor / 医用生物力学

Objective To investigate the effect from different pore sizes of co culture inserts on the permeability of biomacromolecules through polyethylene terephthalate (PET) membrane so as to solve the key technology problem in mechanobiology experiment on vascular cells. Methods Inserts with 0.4 μm and 1.0 μm pores on the PET membrane were studied using flow chamber system. Low shear stress was subjected to the co-cultured system of endothelial cell (EC)/vascular smooth muscle cell (VSMC) and the concentration of platelet-derived growth factor BB (PDGF-BB) was detected by ELISA. Under the static condition, vascular cells were cultured on the plate (with no cell on PET membrane), on the outer side of PET membrane, and on the both sides of PET membrane, respectively. Then the recombinants PDGF-BB (rPDGF-BB) were added on the different sides of PET membrane. Western blotting was used to detect the change in expressions of p-ERK1/2, p-Akt and Lamin after cells were stimulated by rPGDF BB. Results After low shear stress subjection for 12 h, the concentration of PDGF-BB in the medium from VSMC side was significantly higher than that from EC-side. rPDGF-BB passed through 0.4 μm and 1.0 μm pores on the PET membrane and modulated expressions of p-ERK1/2, p-Akt and Lamin A in cells cultured on the opposite side of PET membrane and cells cultured on the plate separately. When cells were cultured on the both sides of PET membrane, rPDGF-BB only stimulated cells cultured on the same side of 0.4 μm pores on PET membrane, but had no specific effect on cells cultured on the opposite side. Conclusions PET membrane with both 0.4 μm and 1.0 μm pores was permeable to PDGF-BB, and cells cultured on the membrane could affect the permeability. The efficiency of PDGF BB passing through 0.4 μm pores was significantly repressed with cells cultured on the both sides, which was more similar to that in vivo.

Losartan Inhibits Vascular Smooth Muscle Cell Proliferation through Activation of AMP-Activated Protein Kinase

Losartan is a selective angiotensin II (Ang II) type 1 (AT1) receptor antagonist which inhibits vascular smooth muscle cells (VSMCs) contraction and proliferation. We hypothesized that losartan may prevent cell proliferation by activating AMP-activated protein kinase (AMPK) in VSMCs. VSMCs were treated with various concentrations of losartan. AMPK activation was measured by Western blot analysis and cell proliferation was measured by MTT assay and flowcytometry. Losartan dose- and time-dependently increased the phosphorylation of AMPK and its downstream target, acetyl-CoA carboxylase (ACC) in VSMCs. Losartan also significantly decreased the Ang II- or 15% FBS-induced VSMC proliferation by inhibiting the expression of cell cycle associated proteins, such as p-Rb, cyclin D, and cyclin E. Compound C, a specific inhibitor of AMPK, or AMPK siRNA blocked the losartan-induced inhibition of cell proliferation and the G0/G1 cell cycle arrest. These data suggest that losartan-induced AMPK activation might attenuate Ang II-induced VSMC proliferation through the inhibition of cell cycle progression.