Effect of vessel number on computational fluid dynamics in vascular networks / 中国组织工程研究

BACKGROUND:Mechanical factors can affect the angiogenic ability of vascular endothelial cells.How the vessel number affects the hydrodynamic properties of microvessels remains to be clarified. OBJECTIVE:To investigate the influence of vessel number on the hydrodynamics of vascular networks based on computational fluid dynamics. METHODS:Three three-dimensional models of vascular network with different vessel numbers were constructed using the Geometry module of ANSYS 19.0 software,and then the vascular network was meshed to tetrahedral elements in Mesh module.The vascular network was assumed to rigid wall without slip,and the blood was assumed to laminar,viscous,and incompressible Newtonian fluid.Blood density,velocity,and a series of blood viscosity coefficients were also established.The Navier-Stokes equation was used for calculation.Hydrodynamic properties of different parts of vascular network with different vessel numbers were analyzed and compared. RESULTS AND CONCLUSION:The streamline,velocity,and mass flow all had the same trend in the vascular network,that is,the outlet and inlet were higher and the middle junction of vascular network was lower.The more the number of vessels,the thinner the blood flow lines in each part of the vascular network.Also,the velocity,mass flow,and wall shear decreased with the increase of the number of blood vessels.Therefore,the changes in vessel number could influence the hydrodynamic environment in the vascular network.Computational fluid dynamics indicates that the changes in vessel numbers can influence the hydrodynamic properties of blood,and provides a new idea for treating bone hypoperfusion-induced diseases(fracture nonunion,bone defect,osteoporosis,etc.)through tonifying kidney and activating blood circulation based on the coupling between angiogenesis and osteogenesis.

Investigation of the technique of esophageal stent re-implantation / 南方医科大学学报

<p><b>OBJECTIVE</b>To analyze the causes of failure of esophageal stent implantation and explore technical improvement of re-implantation of esophageal stent (RIES).</p><p><b>METHODS</b>According to the conditions of the failed stent implantation, 32 patients who required RIES underwent placement of more appropriate esophageal stents with an improved implantation technique. The patients were followed up for 6 months after the operation to evaluate the effects of RIES.</p><p><b>RESULTS</b>The success rate of the operation was 96.9% in these cases, and the esophageal conditions including stricture and fistula were effectively relieved. During the 6-month follow-up, stent migration occurred in 4 cases (12.5%), and esophageal fistula in the upper edge of the re-implanted stent occurred in 2 cases. No stent loss, bleeding, or stricture was found in these cases.</p><p><b>CONCLUSION</b>The improved technique is effective for stent re-implantation after failed esophageal stent implantation with reduced complications associated with esophageal stenting.</p>

Preparation of small-caliber expanded poly(tetrafluoroethylene) vascular grafts applied by silk fibroin film with surface sulfonation by low temperature plasma treatment / 中国组织工程研究

BACKGROUND: Silk fibroin film showed an anti-coagulated blood activity following sulfurous acid treatment; however, its flexibility and anti-tension were poor. If the silk flbroin film was coated on small-caliber expanded poly(tetrafiuoroethylene) (ePTFE) vascular grafts prior to surface sulfonation, the adverse effects were improved and the blood compatibility of ePTFE vascular grafts were remarkably enhanced. OBJECTIVE: To research the preparation of ePTFE vascular grafts applied by surface sulfonation of silk flbroin film by low temperature plasma treatment. METHODS: The ePTFE vascular grafts were treated with low temperature plasma and coated on the surface of silk fibroin. The compound was then sulfonated with low temperature plasma. The ePTFE vascular grafts were considered as the controls to detect contact angle and sulfonation. RESULTS AND CONCLUSION: The contact angle was decreased gradually form 87.7°to 65.1° following low temperature plasma treatment. Moreover, the contact angle was 106.2° following coating silk flbroin film and 92.9°following sulfonation. X-raylight-electron spectrometer demonstrated that percents of sulfur element on the surfaces of the combined blood vessel was 2.89%, respectively, while that of the control film was only 0.12%. The X-ray light-electron spectrometer also showed that most of the sulfur element were sulfonic group (-SO_3H). The results suggested the feasibility of the preparation of the combined blood vessel.