The Experimental Study of Repairing Cartilage Defects Using a Bioreactor with Chondrocyte and Osteoblast Composites

This work aimed to evaluate the repair of cartilage defects using a bioreactor with chondrocyte and osteoblast composites. Our study involved co-culturing chondrocyte osteoblast composites using a bioreactor, treating cartilage defects with cell-β-TCP composites implanted into osteochondral defects in canine models in vivo. Composites were implanted using techniques of mosaicplasty, in which chondrocyte-β-TCP scaffold composites are placed in the top of the defect and osteoblast-β-TCP scaffold composites are implanted in the bottom of the defect. Our results as following, observations were made using electron microscopy. The induced chondrocytes and osteoblasts demonstrated good adhesion progression and proliferation in the β-TCP scaffold. At 16 weeks post-operation, the repaired tissues in the experimental group had established their thickness to the full depth of the original defects. In the control group, chondrocytes were arranged irregularly, and only part of the repaired defect consisted of fibrous tissue. In contrast, the defects in the control group were repaired only with fibrous tissue. In conclusion, perfusion culture permitted continuous nutrient supply and gas exchange to the center of a large scaffold. The perfusion bioreactor facilitates chondrocyte and osteoblast survival and proliferation through utilization of a three-dimensional scaffold.     

Fabrication and Evaluation of Porous Keratin/chitosan (KCS) Scaffolds for Effectively Accelerating Wound Healing*

ObjectiveTo develop a dressing with desired antibacterial activity, good water maintaining ability and mechanical properties for wound healing and skin regeneration. MethodsThe chitosan with different concentrations were added in keratin solution to form porous keratin/chitosan (KCS) scaffolds. The morphological characteristics, chemical composition, wettability, porosity, swelling ratio and degradation of the scaffolds were evaluated. The antibacterial activity was tested by usingS. aureusandE. colisuspension for 2 h. And L929 fibroblast cells culture was used to evaluate the cytotoxicity of the KCS scaffolds. ResultsThe adding of chitosan could increase the hydrophobicity, decrease porosity, swelling ratio and degradation rate of the KCS porous scaffolds.Mechanical properties of KCS scaffolds could be enhanced and well adjusted by chitosan. KCS scaffolds could obviously decrease bacteria number.The proliferation of fibroblast cells in porous KCS patch increased firstly and then decreased with the increase of chitosan concentration. It was appropriate to add 400 μg/mL chitosan to form porous KCS scaffold for achieving best cell attachment and proliferation compared with other samples. ConclusionThe porous KCS scaffold may be used as implanted scaffold materials forpromoting wound healing and skinregeneration.     

Degradation of human hair keratin scaffold material used to repair in-jured skeletal muscles of rabbits

Objective: To explore the mechanism of the degradation of human hair keratin (HHK) scaffold material implanted in damaged skeletal muscle tissues. Methods : Six New Zealand rabbits with HHK scaffold material implants (composed of 3 different types of HHK material with varied degradation speed) after mus-clectomy were divided into 3 groups (2 in each group) to observe the degradation of the material at 1, 3, 6 weeks after operation. Another rabbit without operation was used as the control group. The degradation of HHK was observed with light microscopy, histochemistry of ubiquitin and electron microscopy. Results: Light microscopy showed that human hair cuticles fell off from the HHK material and emerged, and the macrophagocytes and multinucleate giant cells were attached onto the surface of the material, which became homogeneous at the first postoperative week. The HHK scaffold material was degraded into particles that was phagocytosed by macrophagocytes and multinucleate giant cells at the third week. Ubiquitin enzymatic histochemistry showed that the macrophagocytes and the multinucleate giant cells were positive at the first week. Under electron microscope, HHK scaffold material was degraded into particles, and at the sixth week, part of HHK scaffold material was further degraded. Conclusion : Large mass of the HHK scaffold material is degraded via ubiquitin system, and the resultant particles are phagocytosed and degraded with the cooperation of lysosome and ubiquitin.     

Study on the biocompatibility of PLGA with tissus cell in vivo

Objective To study the biocompatbility of PLGA with tissue cell after implantation into the injured spinal cord of rat. Methods Schwann eels and neural stem cells were harvested and cultured in vitro, Then we constructed PLGA-eell complex and implanted the complex into the injured site of T9 SCI models developed from Wistar rats. Then we observed the degradation of the porous scaffold and the growth of tissue eels in the scaffold through electron microscope at different time. Results The PLGA in the scaffold-cells complex gradually degenerated under scanning electron microscope.[第一段]     

Synthesis and characterization of UPPE-PLGA-rhBMP2 scaffolds for bone regeneration

A novel unsaturated polyphosphoester(UPPE) was devised in our previous research,which is a kind of promising scaffold for improving bone regeneration.However,the polymerization process of UPPE scaffolds was unfavorable,which may adversely affect the bioactivity of osteoinductive molecules added if necessary,such as recombinant human bone morphogenetic protein-2(rhBMP2).The purpose of this study was to build a kind of optimal scaffold named UPPE-PLGA-rhBMP2(UPB) and to investigate the bioactivity of rhBMP2 in this scaffold.Furthermore,the cytotoxicity and biocompatibility of UPB scaffold was assessed in vitro.A W1/O/W2 method was used to fabricate PLGA-rhBMP2 microspheres,and then the microspheres were added to UPPE for synthesizing UPB scaffold.The morphological characters of PLGA-rhBMP2 microspheres and UPB scaffolds were observed under the scanning electron microscopy and laser scanning confocal microscopy.The cumulative release of UPB scaffolds was detected by using ELISA.The cytotoxicity and biocompatibility of UPB scaffolds were evaluated through examining the adsorption and apoptosis of bone marrow stromal cells(bMSCs) seeded on the surface of UPB scaffolds.The bioactivity of rhBMP2 in UPB scaffolds was assessed through measuring the alkaline phosphates(ALP) activity in bMSCs seeded.The results showed that UPB scaffolds sequentially exhibited burst and sustained release of rhBMP2.The cytotoxicity was greatly reduced when the scaffolds were immersed in buffer solution for 2 h.bMSCs attached and grew on the surface of soaked UPB scaffolds,exerting well biocompatibility.The ALP activity of bMSCs seeded was significantly enhanced,indicating that the bioactivity of rhBMP2 remained and still took effect after the unfavorable polymerization process of scaffolds.It was concluded that UPB scaffolds have low cytotoxicity,good biocompatibility and preserve bioactivity of rhBMP2.UPB scaffolds are promising in improving bone regeneration.     

A surface-modified biodegradable urethral scaffold seeded with urethral epithelial cells

Background  Efficient cell adhesion and proliferation is a central issue in cell-based tissue engineering, which offers great promise for repair of urethral defects or strictures. This study evaluated the adhesion and growth of rabbit uroepithelium on a surface-modified three-dimensional poly-L-lactic acid (PLLA) scaffold.

Methods  Urethral mucosa were harvested from male New Zealand rabbits and the urothelium were dissociated and then cultured. Immunocytochemistry on cultured uroepithelium for pancytokeratin and uroplakin II and TE-7 confirmed pure populations. After in vitro proliferation, cells were seeded onto a surface-modified urethral scaffold with non-knitted filaments. The morphology and viability of the cells were examined by immunohistochemical and fluorescence staining. Inverted and scanning microscopes were used to document cell growth and adhesion.

Results  Three to five days after primary culture, the uroepithelial cells gradually became confluent, assuming a cobblestone pattern. The filaments of the urethral scaffold had excellent biocompatibility and allowed growth of the uroepithelium, without affecting viability. The uroepithelial cells adhered to and grew well on the scaffold. After 3–7 days, the cells grew vigorously and meshes of the scaffold were full of uroepitheliums.

Conclusions  The surface-modified urethral scaffold with non-knitted filaments allows the growth of uroepithelium and can serve as a carrier for the tissue engineering of urethra.

     

Biphasic calcium phosphate nano-composite scaffolds reinforced with bioglass provide a synthetic alternative to autografts in a canine tibiofibula defect model

Background Bone grafting is commonly used to repair bone defects.As the porosity of the graft scaffold increases,bone formation increases,but the strength decreases.Early attempts to engineer materials were not able to resolve this problem.In recent years,nanomaterials have demonstrated the unique ability to improve the material strength and toughness while stimulating new bone formation.In our previous studies,we synthesized a nano-scale material by reinforcing a porous β-tricalcium phosphate （β-TCP） ceramic scaffold with Na2O-MgO-P2O5-CaO bioglass （β-TCP/BG）.However,the in vivo effects of the β-TCP/BG scaffold on bone repair remain unknown.Methods We investigated the efficacy of β-TCP/BG scaffolds compared to autografts in a canine tibioflbula defect model.The tibioflbula defects were created in the right legs of 12 dogs,which were randomly assigned to either the scaffold group or the autograft group （six dogs per group）.Radiographic evaluation was performed at 0,4,8,and 12 weeks post-surgery.The involved tibias were extracted at 12 weeks and were tested to failure via a three-point bending.After the biomechanical analysis,specimens were subsequently processed for scanning electron microscopy analysis and histological evaluations.Results Radiographic evaluation at 12 weeks post-operation revealed many newly formed osseous calluses and bony unions in both groups.Both the maximum force and break force in the scaffold group （n=6） were comparable to those in the autograft group （n=6,P ＞0.05）,suggesting that the tissue-engineered bone repair achieved similar biomechanical properties to autograft bone repair.At 12 weeks post-operation,obvious new bone and blood vessel formations were observed in the artificial bone of the experimental group.Conclusions The results demonstrated that new bone formation and high bone strength were achieved in the β-TCP/ BG scaffold group,and suggested that the β-TCP/BG scaffold could be used as a synthetic alternative to autografts for the repair of bone defects.     

Development and potential of a biomimetic chitosan/type Ⅱ collagen scaffold for cartilage tissue engineering

Background Damaged articular cartilage has very limited capacity for spontaneous healing. Tissue engineering provides a new hope for functional cartilage repair. Creation of an appropriate cell carrier is one of the critical steps for successful tissue engineering. With the supposition that a biomimetic construct might promise to generate better effects, we developed a novel composite scaffold and investigated its potential for cartilage tissue engineering.Methods Chitosan of 88% deacetylation was prepared via a modified base reaction procedure. A freeze-drying process was employed to fabricate a three-dimensional composite scaffold consisting of chitosan and type Ⅱcollagen. The scaffold was treated with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide. Ultrastructure and tensile strength of the matrix were carried out to assess its physico-chemical properties. After subcutaneous implantation in rabbits, its in vivo biocompatibility and degradability of the scaffold were determined. Its capacity to sustain chondrocyte growth and biosynthesis was evaluated through cell-scaffold co-culture in vitro. Results The fabricated composite matrix was porous and sponge-like with interconnected pores measuring from 100－250 μm in diameter. After cross-linking, the scaffold displayed enhanced tensile strength. Subcutaneous implantation results indicated the composite matrix was biocompatible and biodegradable. In intro cell-scaffold culture showed the scaffold sustained chondrocyte proliferation and differentiation, and maintained the spheric chondrocytic phenotype. As indicated by immunohistochemical staining, the chondrocytes synthesized type Ⅱ collagen. Conclusions Chitosan and type Ⅱ collagen can be well blended and developed into a porous 3-D biomimetic matrix. Results of physico-chemical and biological tests suggest the composite matrix satisfies the constraints specified for a tissue-engineered construct and may be used as a chondrocyte carrier for cartilage tissue engineering.     

High volume practice proved the safety of off-pump coronary artery bypass surgery in left main coronary artery lesions: a two-year single center experience

Background  Left main coronary artery (LMCA) stenosis has been recognized as a risk factor for early death among patients undergoing coronary artery bypass grafting (CABG). This study aimed to assess if LMCA lesions pose an additional risk of early or mid-term mortality and/or a major adverse cardiac and cerebrovascular event (MACCE) after off-pump coronary artery bypass grafting (OPCABG), compared with non-left main coronary artery stenosis (non-mainstem disease).

Methods  From January 1, 2009 to December 31, 2010, 4869 patients had a primary isolated OPCABG procedure at Beijing Anzhen Hospital. According to the pathology of LMCA lesions, they were retrospectively classified as a non-mainstem disease group (n=3933) or a LMCA group (n=936). Propensity scores were used to match the two groups, patients from the non-mainstem disease group (n=831) were also randomly selected to match patients from the LMCA group (n=831). Freedom from MACCE in the two groups was calculated using the Kaplan-Meier method.

Results  The difference in the mortality and the rate of MACCE during the first 30 days between the non-mainstem disease group and the LMCA group did not reach statistical significance (P=0.429, P=0.127 respectively). With a mean follow-up of (12.8±7.5) months and a cumulative follow-up of 1769.6 patient-years, the difference in the freedom from MACCEs between the two groups, calculated through Kaplan-Meier method, did not reach statistical significance (P=0.831).

Conclusion  Analysis of a high volume of OPCABG procedures proved that LMCA lesions do not pose additional early and mid-term risk to OPCABG. Therefore, a LMCA lesion is as safe as non-mainstem disease lesion during the OPCABG procedure.

     

In vitro cartilage production using an extracellular matrix-derived scaffold and bone marrow-derived mesenchymal stem cells

Background Cartilage repair is a challenging research area because of the limited healing capacity of adult articular cartilage.We had previously developed a natural,human cartilage extracellular matrix （ECM）-derived scaffold for in vivo cartilage tissue engineering in nude mice.However,before these scaffolds can be used in clinical applications in vivo,the in vitro effects should be further explored.Methods We produced cartilage in vitro using a natural cartilage ECM-derived scaffold.The scaffolds were fabricated by combining a decellularization procedure with a freeze-drying technique and were characterized by scanning electron microscopy （SEM）,micro-computed tomography （micro-CT）,histological staining,cytotoxicity assay,biochemical and biomechanical analysis.After being chondrogenically induced,the induction results of BMSCs were analyzed by histology and Immunohisto-chemistry.The attachment and viability assessment of the cells on scaffolds were analyzed using SEM and LIVE/DEAD staining.Cell-scaffold constructs cultured in vitro for 1 week and 3 weeks were analyzed using histological and immunohistochemical methods.Results SEM and micro-CT revealed a 3-D interconnected porous structure.The majority of the cartilage ECM was found in the scaffold following the removal of cellular debris,and stained positive for safranin O and collagen Ⅱ.Viability staining indicated no cytotoxic effects of the scaffold.Biochemical analysis showed that collagen content was （708.2±44.7）μg/mg,with GAG （254.7±25.9） μg/mg.Mechanical testing showed the compression moduli （E） were （1.226±0.288） and （0.052±0.007） MPa in dry and wet conditions,respectively.Isolated canine bone marrow-derived stem cells （BMSCs） were induced down a chondrogenic pathway,labeled with PKH26,and seeded onto the scaffold.Immunofluorescent staining of the cell-scaffold constructs indicated that chondrocyte-like cells were derived from seeded BMSCs and excreted ECM.The cell-scaffold constructs contained pink,smooth and translucent cartilage-like tissue after 3 weeks of culture.We observed evenly distributed cartilage ECM proteoglycans and collagen type Ⅱ around seeded BMSCs on the surface and inside the pores throughout the scaffold.Conclusion This study stuggests that a cartilage ECM scaffold holds much promise for in vitro cartilage tissue engineering.     

Compatibility of olfactory ensheathing cells with functionalized self-assembling peptide scaffold in vitro

Background Olfactory ensheathing cell （OEC） transplantation is a promising or potential therapy for spinal cord injury （SCI）. However, the effects of injecting OECs directly into SCI site have been limited and unsatisfied due to the complexity of SCI. To improve the outcome, proper biomaterials are thought to be helpful since these materials would allow the cells to grow three-dimensionally and guide cell miqration.     

Progress in various crosslinking modification for acellular matrix

Objective To review the current crosslinking strategies for acelluar matrix scaffold,laying the foundation for subsequent experiment.Data sources Data were mainly obtained from recent papers published in PubMed or indexed by Web of Science,with keyword like crosslinking.Results Various crosslinking strategies,including chemical,physical and biological methods,have been introduced to facilitate the performance of fresh acellular matrix.Chemical crosslinking reagents,involved in synthetic and naturally derived agents,need to be eliminated before implantation in case of their potential biotoxicity,although several crosslinking agents with less toxicity and specific characteristics have been developed.Physical crosslinking methods present to be safe,additive-free and relatively controllable for rapid surface functionalization with no consideration of remaining radioactivity.Biological crosslinking strategies have attracted great interest,and have been demonstrated to enhance collagen-based crosslinking since their preparations do not need toxic or potentially biologically contaminated substances and can be carried out under physiological conditions.Conclusions Kinds of crosslinking methods with its potential advantages have been developed to modify raw acelluar matrix,of which the performance are promising after being crosslinked by several crosslinking treatments.Further preclinical and clinical evaluations should be taken to vertify their safety and efficacy for the tissues and organs substitutes in tissue and regenerative medicine.     

Randomized study on the safety and efficacy of dual-axis rotational versus standard coronary angiography in

Background  Dual-axis rotational coronary angiography (DARCA) was developed as an innovative adaptation of rotational angiography (RA), but it requires a longer coronary injection compared to standard coronary angiography (SA). As the body of the average Chinese patient is smaller than that of most western patients, with the same contrast injection time, the risk of complications from the contrast agent is increased in this population. The purpose of this study was to assess the clinical safety and efficacy of DARCA in the diagnosis of coronary artery disease (CAD) in the Chinese population by directly comparing it to SA.

Methods  Two hundred Chinese patients were randomized to either the SA group (n=100) or DARCA group (n=100). Contrast utilization, radiation exposure and procedure time were recorded for each modalities. Blood pressure (BP), heart rate (HR) pre and post injection symptoms and any arrhythmias were recorded.

Results  Compared to the SA group, there was a 42% reduction in contrast utilization, 55% reduction in radiation exposure and a 31% shorter procedure time in the DARCA group. In both groups, there were slight declines in the systolic BP values in the left coronary artery (LCA) post injection (P <0.01). Moreover, post injection HRs for the LCA were also reduced in the DARCA group (P <0.01). But all of these changes were small, transient and without clinical importance. Only one patient (1%) in the DARCA group had an attack of ventricular tachycardia immediately post injection and it resolved by itself during LCA angiography. No arrhythmias occurred in the SA group.

Conclusion  DARCA is a safe, efficient, and clinically comparable alternative to SA in the diagnosis of coronary artery disease in the Chinese population with less contrast utilized, which is less radiation exposure and a shorter procedure time than SA.

     

Clinical relevance of angiographic coronary collaterals during primary coronary intervention for acute ST-elevation myocardial infarction

Background Collaterals to occluded infarct-related coronary arteries （IRA） have been observed after the onset of acute ST-elevation myocardial infarction （STEMI）.We sought to investigate the impact of early coronary collateralization,as evidenced by angiography,on myocardial reperfusion and outcomes after primary percutaneous coronary intervention （PCI）.Methods Acute procedural results,ST-segment resolution （STR）,enzymatic infarct size,echocardiographic left ventricular function,and major adverse cardiac events （MACE） at 6-month follow-up were assessed in 389 patients with STEMI undergoing primary PCI for occluded IRA （TIMI flow grade 0 or 1） within 12 hours of symptom-onset.Angiographic coronary collateralization to the occluded IRA at first contrast injection was graded according to the Rentrop scoring system.Results Low （Rentrop score of 0 or 1） and high （Rentrop score of 2 or 3） coronary collateralization was detected in 329 and 60 patients,respectively.Patients with high collateralization more commonly had prior stable angina and right coronary artery occlusion,but less often had left anterior descending artery occlusion.At baseline,these patients presented with less extent of ST-segment elevation and lower serum levels of creatine kinase myocardial band （CK-MB） and cardiac troponin Ⅰ （cTnl）.Procedural success rate,STR,corrected TIMI flame count,and area under the curve of CK-MB and cTnl measurements after the procedure were similar between patients with high collateralization and those with low collateralization （for all comparisons P＞0.05）.There were no differences in left ventricular ejection fraction and rates of MACE at 6 months according to baseline angiographic collaterals to occluded IRA.Conclusions In patients with acute STEMI undergoing primary PCI within 12 hours of symptom-onset,coronary collateralization to the occluded IRA was influenced by clinical and angiographic features.Early recruitment of collaterals limits infarct size at baseline,but has no significant impact on myocardial reperfusion after the procedure and subsequent left ventricular function and clinical outcomes.     

Nine-month angiographic and two-year clinical follow-up of polymer-free sirolimus-eluting stent versus durable-polymer sirolimus-eluting stent for coronary artery disease: the Nano randomized trial

Background First generation drug-eluting stents （DES） were associated with a high incidence of late stent thrombosis （ST）,mainly due to delayed healing and re-endothelization by the durable polymer coating.This study sought to assess the safety and efficacy of the Nano polymer-free sirolimus-eluting stent （SES） in the treatment of patients with de novo coronary artery lesions.Methods The Nano trial is the first randomized trial designed to compare the safety and efficacy of the Nano polymer-free SES and Partner durable-polymer SES （Lepu Medical Technology,Beijing,China） in the treatment of patients with de novo native coronary lesions.The primary endpoint was in-stent late lumen loss （LLL） at 9-month follow-up.The secondary endpoint was major adverse cardiac events （MACE）,a composite of cardiac death,myocardial infarction or target lesion revascularization.Results A total of 291 patients （Nano group：n=143,Partner group：n=148） were enrolled in this trial from 19 Chinese centers.The Nano polymer-free SES was non-inferior to the Partner durable-polymer DES at the primary endpoint of 9 months （P 〈0.001）.The 9-month in-segment LLL of the polymer-free Nano SES was comparable to the Partner SES （0.34±0.42） mm vs.（0.30±0.48） mm,P=0.21）.The incidence of MACE in the Nano group were 7.6% compared to the Partner group of 5.9% （P=0.75） at 2 years follow-up.The frequency of cardiac death and stent thrombosis was low for both Nano and Partner SES （0.8% vs.0.7%,0.8% vs.1.5%,both P=1.00）.Conclusions In this multicenter randomized Nano trial,the Nano polymer-free SES showed similar safety and efficacy compared with the Partner SES in the treatment of patients with de novo coronary artery lesions.Trials in patients with complex lesions and longer term follow-up are necessary to confirm the clinical performance of this novel Nano polymer-free SES.     

Ectopic osteogenesis and scaffold biodegradation of tissue engineering bone composed of chitosan and osteo-induced bone marrow mesenchymal stem cells in vivo

Background Chitosan （CS） scaffolds combined with osteogenically induced bone marrow mesenchymal stem cells （BMSCs） have been proved to be promising substitutes for repairing bone defects.Nevertheless,the bone-forming and scaffold-biodegrading processes are seldom studied.This study aimed to determine the osteogenic ability of CS/osteoinduced BMSC composites by observing the bone-forming process and explore the relationship between bone formation and scaffold biodegradation.Methods The CS/osteo-induced BMSC composites （CS＋cells group） and the CS scaffolds （CS group） were,respectively,implanted into SD rat thigh muscles.At 2,4,6,8,and 12 weeks postoperatively,the rat femurs were scanned by CT,and the CT values of the implants were measured and comparatively analyzed.Subsequently,the implants were harvested and stained with hematoxylin and eosin and Masson trichrome,and the percentages of bone area,scaffold area,and collagen area were calculated and compared between the two groups.Results The imaging results showed that the densities of implants of the two groups gradually increased along with time,but the CT values of implants in the CS＋cells group were much higher than in the CS group at the same time point （P ＜0.05）.The histological results showed that the de novo bone and collagen formed in the pores of the scaffolds and gradually increased since 2 weeks postoperation in both groups,and the scaffold gradually degraded along with the boneforming process.However,the comparative analysis results showed that the CS＋cells group gained more de novo bone and collagen formation and had less scaffold than the CS group at the same time point （P ＜0.05）.Conclusion The CS/osteo-induced BMSC composites are excellent bone tissue engineering substitutes,and the scaffold biodegradation is accordant with the bone formation.     

Hemodynamic change in wall shear stress in patients with coronary bifurcation lesions treated by double kissing crush or single-stent technique

Background  Fluid dynamic mechanisms attributed to coronary bifurcation lesions remain a subject of study. The present study aimed at investigating the hemodynamic change of wall shear stress (WSS) in patients with coronary bifurcation lesions treated by double kissing (DK) crush or one-stent with final kissing balloon inflation (FKBI).

Methods  Eighty-one patients with bifurcation lesions treated by stenting who had 3-D model reconstruction were studied. The bifurcation vessels were divided into main vessel (MV), main branch (MB), side branch (SB), and polygon of confluence (POC). MB and SB were classified by internal- and lateral-subsegments, respectively.

Results  The baseline magnitude of WSS in proximal MV, POC-MV, POC-MB, POC-SB and MB-internal segments increased significantly, compared to MB-lateral, SB-internal and SB-lateral. DK crush had the potential of uniformly reducing WSS, turbulent index and the WSS gradient. The WSS value at the POC-SB and SB in the one-stent group remained higher. The turbulent index and WSS gradient between the POC-SB minus the SB-lateral had equal predictive values for in-stent restenosis (ISR).

Conclusion  Fluid dynamic results favor the use of DK crush over the one-stent technique.

     

Comparison of low-dose sequences of dual-source CT and echocardiography for preoperative evaluation of aortic valve disease

Background Accurate evaluation of coronary artery,aortic valve annulus diameter （AVAD）,and cardiac function in patients with aortic valve disease is of great significance for surgical strategy.In this study,we explored the preoperative evaluation of low-dose sequence （MinDose sequence） scan of dual-source CT （DSCT） for those patients.Methods Forty patients suspected for aortic valve disease （the experimental group） underwent MinDose sequence of DSCT to observe coronary artery,AVAD,and left ventricular ejection fraction （LVEF）.Another 33 subjects suspected for coronary artery disease （the control group） underwent conventional retrospective electrocardiographically-gated sequence of DSCT.Two-dimensional transthoracic echocardiography （2D-TTE） and four-dimensional transthoracic echocardiography （4D-TTE） were applied in the experimental group to measure AVAD and LVEF and compared with MinDose-DSCT.Results There was a strong correlation between LVEFs measured by 2D-TTE and MinDose-DSCT （r=0.87,P ＜0.01）,as well as between 4D-TTE and MinDose-DSCT （r=0.90,P ＜0.01）.AVAD measured by MinDose-DSCT was in good agreement with corresponding measurements by 2D-TTE （r=0.90,P ＜0.01）.The effective dose in the experimental group was 63.54％ lower than that in the control group.Conclusions MinDose sequence of DSCT with a low radiation dose serving as a one-stop preoperative evaluation makes effective assessment of the coronary artery,AVAD,and LVEF for patients with aortic valve disease.     

Short-term safety and efficacy of the biodegradable iron stent in mini-swine coronary arteries

Background To overcome the drawbacks of permanent years. The bioabsorbable polymer vascular scaffold （BVS） stents, biodegradable stents have been studied in recent was the first bioabsorbable stent to undergo clinical trials, demonstrating safety and feasibility in the ABSORB studies. Iron can potentially serve as the biomatedal for biodegradable stents. This study aimed to assess the short4erm safety and efficacy of a biodegradable iron stent in mini-swine coronary arteries. Methods Eight iron stents and eight cobalt chromium alloy （VISION） control stents were randomly implanted into the LAD and RCA of eight healthy mini-swine, respectively. Two stents of the same metal base were implanted into one animal. At 28 days the animals were sacrificed after coronary angiography, and histopathological examinations were performed. Results Histomorphometric measurements showed that mean neointimal thickness （（0.46±0.17） mm vs. （0.45±0.18） mm, P=0.878）, neointimal area （（2.55±0.91） mm2 vs. （3.04±1.15） mm2, P=0.360） and percentage of area stenosis （（44.50±11.40）% vs. （46.00±17.95）%, P=0.845） were not significantly different between the iron stents and VISION stents. There was no inflammation, thrombosis or necrosis in either group. The scanning electron microscopy （SEM） intimal injury scores （0.75±1.04 vs. 0.88±0.99, P=0.809） and number of proliferating cell nuclear antigen （PCNA） positive staining cells were not significantly different between the two groups. The percentage of neointimal coverage by SEM examination was numerically higher in iron stents than in VISION stents （（84.38±14.50）% vs. （65.00±22.04）%, P=0.057）, but the difference was not statistically significant. Iron staining in the tissue surrounding the iron stents at 28 days was positive and the vascular wall adjacent to the iron stent had a brownish tinge, consistent with iron degradation. No abnormal histopathological changes were detected in coronary arteries or major organs. Conclusions The biodegradable iron stent has good biocompatibility and short-term safety and efficacy in the mini- swine coronary artery. Corrosion of iron stents is observed at four weeks and no signs of organ toxicity related to iron degradation were noted.