The Experts below are selected from a list of 17754 Experts worldwide ranked by ideXlab platform
Can Wen - One of the best experts on this subject based on the ideXlab platform.
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a simply prepared small diameter Artificial Blood vessel that promotes in situ endothelialization
2017Co-Authors: Hongfeng Guo, Weiwei Dai, Dehui Qian, Zhexue Qin, Yan Lei, Xiaoyu Hou, Can WenAbstract:Abstract Synthetic grafts are of limited use in small-diameter vessels (Φ Statement of Significance (1) SDF-1α/VEGF loaded PU conduits were simply prepared by electrospinning. The cytokines with definite and potent effects on angiogenesis were used to avoid complicated mechanism researches. Compared with most of the current vascular grafts which are of poor strength or elasticity, the conduits have favorable mechanical property. All of these inhibit the conduits from occlusion, and thus improve their long-term patency rate. (2) For the in vivo tests, the dogs did not receive any anticoagulant medication in the follow-up period to expose the grafts to the strictest conditions. In vivo endothelialization of the conduits was thoroughly investigated by Sonography, HE staining, SEM and LSCM. The study will be helpful for the construction of small-diameter Artificial Blood vessels.
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a simply prepared small diameter Artificial Blood vessel that promotes in situ endothelialization
2017Co-Authors: Hongfeng Guo, Weiwei Dai, Dehui Qian, Zhexue Qin, Yan Lei, Xiaoyu Hou, Can WenAbstract:Synthetic grafts are of limited use in small-diameter vessels (Φ<6mm) due to the poor patency rate. The inability of such grafts to achieve early endothelialization together with the compliance mismatch between the grafts and the native vessels promote thrombosis, which eventually leads to graft occlusion. In the current study, stromal cell-derived factor (SDF)-1α/vascular endothelial growth factor (VEGF)-loaded polyurethane (PU) conduits were simply prepared via electrospinning. The mechanical property, drug release behavior and cytocompatibility of the conduits were investigated. The effects of the conduits on endothelial progenitor cell (EPC) mobilization and differentiation were examined in vitro. Then, the conduits were implanted as canine femoral artery interposition grafts. The results revealed that SDF-1α and VEGF were quickly released shortly after implantation, and the conduits exhibited slow and sustained release thereafter. The cytokines had definite effects on EPC mobilization and differentiation in vitro and promoted conduit endothelialization in vivo. The conduits had good tissue compatibility and favorable compliance. All of these features inhibited the conduits from being occluded, thereby improving their long-term patency rate. At 6th month postoperatively, 5 of the 8 grafts were patent while all the 8 grafts without the cytokines were occluded. These findings provide a simple and effective method for the construction of small-diameter Artificial Blood vessels with the aim of facilitating early endothelialization and improving long-term patency. STATEMENT OF SIGNIFICANCE: (1) SDF-1α/VEGF loaded PU conduits were simply prepared by electrospinning. The cytokines with definite and potent effects on angiogenesis were used to avoid complicated mechanism researches. Compared with most of the current vascular grafts which are of poor strength or elasticity, the conduits have favorable mechanical property. All of these inhibit the conduits from occlusion, and thus improve their long-term patency rate. (2) For the in vivo tests, the dogs did not receive any anticoagulant medication in the follow-up period to expose the grafts to the strictest conditions. In vivo endothelialization of the conduits was thoroughly investigated by Sonography, HE staining, SEM and LSCM. The study will be helpful for the construction of small-diameter Artificial Blood vessels.
Lih-sheng Turng - One of the best experts on this subject based on the ideXlab platform.
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Long-term nitric oxide release for rapid endothelialization in expanded polytetrafluoroethylene small-diameter Artificial Blood vessel grafts
2020Co-Authors: Dongfang Wang, Lixia Wang, Xiaofeng Wang, Shujie Yan, Galip Yilmaz, Lih-sheng TurngAbstract:Abstract Without a complete and confluent endothelial layer covering the luminal surface, expanded polytetrafluoroethylene (ePTFE) small-diameter (
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Artificial small diameter Blood vessels materials fabrication surface modification mechanical properties and bioactive functionalities
2020Co-Authors: Dongfang Wang, Lih-sheng TurngAbstract:Cardiovascular diseases, especially ones involving narrowed or blocked Blood vessels with diameters smaller than 6 millimeters, are the leading cause of death globally. Vascular grafts have been used in bypass surgery to replace damaged native Blood vessels for treating severe cardio- and peripheral vascular diseases. However, autologous replacement grafts are not often available due to prior harvesting or the patient's health. Furthermore, autologous harvesting causes secondary injury to the patient at the harvest site. Therefore, Artificial Blood vessels have been widely investigated in the last several decades. In this review, the progress and potential outlook of small-diameter Blood vessels (SDBVs) engineered in vitro are highlighted and summarized, including material selection and development, fabrication techniques, surface modification, mechanical properties, and bioactive functionalities. Several kinds of natural and synthetic polymers for Artificial SDBVs are presented here. Commonly used fabrication techniques, such as extrusion and expansion, electrospinning, thermally induced phase separation (TIPS), braiding, 3D printing, hydrogel tubing, gas foaming, and a combination of these methods, are analyzed and compared. Different surface modification methods, such as physical immobilization, surface adsorption, plasma treatment, and chemical immobilization, are investigated and are compared here as well. Mechanical requirements of SDBVs are also reviewed for long-term service. In vitro biological functions of Artificial Blood vessels, including oxygen consumption, nitric oxide (NO) production, shear stress response, leukocyte adhesion, and anticoagulation, are also discussed. Finally, we draw conclusions regarding current challenges and attempts to identify future directions for the optimal combination of materials, fabrication methods, surface modifications, and biofunctionalities. We hope that this review can assist with the design, fabrication, and application of SDBVs engineered in vitro and promote future advancements in this emerging research field.
Hongfeng Guo - One of the best experts on this subject based on the ideXlab platform.
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a simply prepared small diameter Artificial Blood vessel that promotes in situ endothelialization
2017Co-Authors: Hongfeng Guo, Weiwei Dai, Dehui Qian, Zhexue Qin, Yan Lei, Xiaoyu Hou, Can WenAbstract:Abstract Synthetic grafts are of limited use in small-diameter vessels (Φ Statement of Significance (1) SDF-1α/VEGF loaded PU conduits were simply prepared by electrospinning. The cytokines with definite and potent effects on angiogenesis were used to avoid complicated mechanism researches. Compared with most of the current vascular grafts which are of poor strength or elasticity, the conduits have favorable mechanical property. All of these inhibit the conduits from occlusion, and thus improve their long-term patency rate. (2) For the in vivo tests, the dogs did not receive any anticoagulant medication in the follow-up period to expose the grafts to the strictest conditions. In vivo endothelialization of the conduits was thoroughly investigated by Sonography, HE staining, SEM and LSCM. The study will be helpful for the construction of small-diameter Artificial Blood vessels.
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a simply prepared small diameter Artificial Blood vessel that promotes in situ endothelialization
2017Co-Authors: Hongfeng Guo, Weiwei Dai, Dehui Qian, Zhexue Qin, Yan Lei, Xiaoyu Hou, Can WenAbstract:Synthetic grafts are of limited use in small-diameter vessels (Φ<6mm) due to the poor patency rate. The inability of such grafts to achieve early endothelialization together with the compliance mismatch between the grafts and the native vessels promote thrombosis, which eventually leads to graft occlusion. In the current study, stromal cell-derived factor (SDF)-1α/vascular endothelial growth factor (VEGF)-loaded polyurethane (PU) conduits were simply prepared via electrospinning. The mechanical property, drug release behavior and cytocompatibility of the conduits were investigated. The effects of the conduits on endothelial progenitor cell (EPC) mobilization and differentiation were examined in vitro. Then, the conduits were implanted as canine femoral artery interposition grafts. The results revealed that SDF-1α and VEGF were quickly released shortly after implantation, and the conduits exhibited slow and sustained release thereafter. The cytokines had definite effects on EPC mobilization and differentiation in vitro and promoted conduit endothelialization in vivo. The conduits had good tissue compatibility and favorable compliance. All of these features inhibited the conduits from being occluded, thereby improving their long-term patency rate. At 6th month postoperatively, 5 of the 8 grafts were patent while all the 8 grafts without the cytokines were occluded. These findings provide a simple and effective method for the construction of small-diameter Artificial Blood vessels with the aim of facilitating early endothelialization and improving long-term patency. STATEMENT OF SIGNIFICANCE: (1) SDF-1α/VEGF loaded PU conduits were simply prepared by electrospinning. The cytokines with definite and potent effects on angiogenesis were used to avoid complicated mechanism researches. Compared with most of the current vascular grafts which are of poor strength or elasticity, the conduits have favorable mechanical property. All of these inhibit the conduits from occlusion, and thus improve their long-term patency rate. (2) For the in vivo tests, the dogs did not receive any anticoagulant medication in the follow-up period to expose the grafts to the strictest conditions. In vivo endothelialization of the conduits was thoroughly investigated by Sonography, HE staining, SEM and LSCM. The study will be helpful for the construction of small-diameter Artificial Blood vessels.
Dongfang Wang - One of the best experts on this subject based on the ideXlab platform.
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Long-term nitric oxide release for rapid endothelialization in expanded polytetrafluoroethylene small-diameter Artificial Blood vessel grafts
2020Co-Authors: Dongfang Wang, Lixia Wang, Xiaofeng Wang, Shujie Yan, Galip Yilmaz, Lih-sheng TurngAbstract:Abstract Without a complete and confluent endothelial layer covering the luminal surface, expanded polytetrafluoroethylene (ePTFE) small-diameter (
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Artificial small diameter Blood vessels materials fabrication surface modification mechanical properties and bioactive functionalities
2020Co-Authors: Dongfang Wang, Lih-sheng TurngAbstract:Cardiovascular diseases, especially ones involving narrowed or blocked Blood vessels with diameters smaller than 6 millimeters, are the leading cause of death globally. Vascular grafts have been used in bypass surgery to replace damaged native Blood vessels for treating severe cardio- and peripheral vascular diseases. However, autologous replacement grafts are not often available due to prior harvesting or the patient's health. Furthermore, autologous harvesting causes secondary injury to the patient at the harvest site. Therefore, Artificial Blood vessels have been widely investigated in the last several decades. In this review, the progress and potential outlook of small-diameter Blood vessels (SDBVs) engineered in vitro are highlighted and summarized, including material selection and development, fabrication techniques, surface modification, mechanical properties, and bioactive functionalities. Several kinds of natural and synthetic polymers for Artificial SDBVs are presented here. Commonly used fabrication techniques, such as extrusion and expansion, electrospinning, thermally induced phase separation (TIPS), braiding, 3D printing, hydrogel tubing, gas foaming, and a combination of these methods, are analyzed and compared. Different surface modification methods, such as physical immobilization, surface adsorption, plasma treatment, and chemical immobilization, are investigated and are compared here as well. Mechanical requirements of SDBVs are also reviewed for long-term service. In vitro biological functions of Artificial Blood vessels, including oxygen consumption, nitric oxide (NO) production, shear stress response, leukocyte adhesion, and anticoagulation, are also discussed. Finally, we draw conclusions regarding current challenges and attempts to identify future directions for the optimal combination of materials, fabrication methods, surface modifications, and biofunctionalities. We hope that this review can assist with the design, fabrication, and application of SDBVs engineered in vitro and promote future advancements in this emerging research field.
Andre F Palmer - One of the best experts on this subject based on the ideXlab platform.
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liposome encapsulated actin hemoglobin leachb Artificial Blood substitutes
2005Co-Authors: Shuliang Li, Jonathan D Nickels, Andre F PalmerAbstract:Abstract A new approach to enhance the circulation persistence of liposomes has been applied to develop liposome-encapsulated actin–hemoglobin (LEAcHb) dispersions as potential Blood substitutes by introducing an actin matrix into the liposome aqueous core. Asymmetric flow field-flow fractionation coupled with multi-angle static light scattering was used to study the shape, size distribution, and encapsulation efficiency of liposome-encapsulated hemoglobin (LEHb) and LEAcHb dispersions. By polymerizing monomeric actin into filamentous actin inside the liposome aqueous core, LEAcHb particles transformed into a disk-like shape. We studied the effect of an encapsulated actin matrix on the size distribution, hemoglobin (Hb) encapsulation efficiency, oxygen affinity, and methemoglobin (MetHb) level of LEAcHb dispersions, and compared them with plain LEHb dispersions (without actin). LEHb, and LEAcHb dispersions extruded through 400 nm membranes were injected into rats and it was observed that LEAcHb dispersions with 1 mg/mL of actin enhanced the circulatory half-life versus LEHb dispersions. The circulatory characteristics of empty PEGylated and non-PEGylated actin–containing liposomes (without Hb) were studied as controls for the LEHb and LEAcHb dispersions in this paper, which displayed maximum circulatory half-lives greater than 72 h. Taken together the results of this study supports our hypothesis that a lipid membrane supported by an underlying actin matrix will extend the circulatory half-life of LEHb dispersions.
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oxidized mono di tri and polysaccharides as potential hemoglobin cross linking reagents for the synthesis of high oxygen affinity Artificial Blood substitutes
2004Co-Authors: Julie H. Eike, Andre F PalmerAbstract:Various oxidized mono/di/tri/poly saccharides were studied as potential hemoglobin (Hb) cross-linkers in order to produce oxygen carriers with high oxygen affinities (low P50apos;s) and high molecular weights (therefore lower macromolecular diffusivities compared to tetrameric Hb). Such physical properties were desired to produce polymerized hemoglobins (PolyHbs) with oxygen release profiles similar to that of human Blood, as was demonstrated in work by Winslow ( 1). In this present study, bovine hemoglobin was cross-linked with a variety of oxidized (ring-opened) saccharides, which resulted in cross-linked Hb species ranging in size from 64 to 6400 kDa (depending on the particular oxidized saccharide used in the reaction) and P50apos;s ranging from 6 to 15 mmHg. A parallel synthetic approach was used to synthesize these carbohydrate-hemoglobin conjugates, and asymmetric flow field-flow fractionation (AFFF) coupled with multi-angle static light scattering (MASLS) was used to measure the absolute molecular weight distribution of these PolyHb dispersions. Cross-linking reactions were conducted at two pHs (6 and 8), with larger cross-linked Hb species produced at pH 8 (where hydrolysis was most likely to occur between glycosidic bonds linking adjacent saccharide rings) rather than at pH 6. The largest molecular weight species formed from these reactions consisted of Hb cross-linked with ring-opened lactose, maltose, methylglucopyranoside, sucrose, trehalose, and 15 kDa and 71 kDa dextran at high pH (pH 8). The most promising Hb cross-linker was methylglucopyranoside, which resulted in very large cross-linked Hb species, with low P50apos;s and lower methemoglobin (metHb) levels compared to the other Hb cross-linking reagents.
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effect of glutaraldehyde concentration on the physical properties of polymerized hemoglobin based oxygen carriers
2004Co-Authors: Julie H. Eike, Andre F PalmerAbstract:Artificial Blood substitutes based on glutaraldehyde cross-linked hemoglobin (PolyHb) are currently being developed for use in human subjects needing Blood transfusions. Despite the commercial development of PolyHb dispersions, a systematic study of the effect of varying the glutaraldehyde to hemoglobin (G-Hb) molar ratio on the resulting PolyHb physical properties (molecular weight distribution and oxygen binding parameters) has not been conducted to date. The results of this study show that increasing the G-Hb molar ratio elicits a general decrease in the P50 (partial pressure of oxygen at which Hb is half saturated with oxygen) and cooperativity and a simultaneous increase in the weight averaged molecular weight (Mw) of the PolyHb dispersion and methemoglobin (MetHb) level. Three PolyHb dispersions (20:1, 30:1, and 40:1 G-Hb molar ratios) displayed potential as Artificial Blood substitutes. The 20:1 PolyHb dispersion resulted in the presence of more intramolecularly cross-linked and non-cross-linked tetramers versus cross-linked species that were larger than a tetramer ( approximately 75% tetrameric and approximately 25% higher-order species), lower MetHb level (8%), and P50 (20.1 mmHg) similar in magnitude to that of non-cross-linked Hb. The 30:1 PolyHb dispersion consisted of more higher-order species ( approximately 76%), higher MetHb level (28%), and lower P50 (13.3 mmHg). The 40:1 PolyHb dispersion resulted in a similar P50 of 13.0 mmHg and similar MetHb level (30%); however, this PolyHb dispersion only consisted of species larger than a tetramer. The molecular weight distribution of PolyHb dispersions was determined using asymmetric flow field-flow fractionator (AFFF) coupled with multiangle static light scattering (MASLS). This is the first time that AFFF-MASLS has been used to characterize the molecular weight distribution of PolyHb dispersions.
