Morphological and Histological Evaluations of 3D-Layered Blood Vessel Constructs Prepared by Hierarchical Cell Manipulation

Three-dimensional (3D)-layered blood vessel constructs consisting of human umbilical artery smooth muscle cells (SMCs) and human umbilical vascular endothelial cells (ECs) were fabricated by hierarchical cell manipulation, and their basic morphology, histology and blood compatibility were evaluated in relation to the EC layers. For the hierarchical cell manipulation, fibronectin-gelatin (FN-G) nanofilms were prepared on the surface of SMC layers to provide a cell adhesive nano-scaffold for the second layer of cells. The layer number of blood vessel constructs was easily controllable from 2 to 7 layers, and the histological evaluation, scanning electron microscope (SEM) and transmission electron microscope (TEM) observations indicated a hierarchical blood vessel analogous morphology. The immunefluorescence staining revealed homogeneous and dense tight-junction of the uppermost EC layer. Furthermore, the nano-meshwork morphology of the FN-G films like a native extracellular matrix was observed inside the blood vessel constructs by SEM. Moreover, a close association between actin microfilaments and the nano-meshworks was observed on the SMC surface by TEM. The blood compatibility of the blood vessel constructs, 4-layered SMC/1-layered EC (4L-SMC/1L-EC), was clearly confirmed by inhibition of platelet adhesion, whereas the blood vessel constructs without EC layers (4L-SMC) showed high adhesion and activation of the platelet. The 3D-blood vessel constructs prepared by hierarchical cell manipulation technique will be valuable as a blood vessel model in the tissue engineering or pharmaceutical fields.     

Platelet adhesion and fusion to endothelial cell facilitate the metastasis of tumor cell in hypoxia-reoxygenation condition

To investigate the relevant molecular mechanisms of platelet in promoting metastasis of tumor cell. The adhesion of fluorescence dye labeled-platelet to human liver sinusoidal endothelial cell (LSEC) line and tumor cell lines were detected by fluorescence microscope and fluorescence plate reader or laser scanning confocal microscope. The relevant adhesion molecules were analyzed by the antibody blockage experiment. The immune colloidal gold transmission electron microscope (TEM), flow cytometry and dye transfer were used to decipher the adhesion and fusion of platelet and LSEC. The tumor cells adhesion to vessels in ischemia condition was analyzed on mouse mesenteric vessels and the metastasis and neovascularization of metastatic foci in pulmonary tissue were also detected after tumor cells injected into nude mice via tail veil. After hypoxia-reoxygenation, tumor cell or LSEC markedly increased its adhesion with platelet, which could be blocked by different antibodies to platelet adhesion molecules. Platelet increased adhesion of tumor cell to LSEC in dose-dependent manner. The fusion of platelet and LSEC was demonstrated by translocation of fluorescent dye from platelet into the adherent LSEC; gpIIb emerged on the LSEC; and confirmed by TEM. The morphological examination found platelet presented between tumor cell and LSEC. Animal experiment indicated that the tumor adhesion to vessels was seldom in normal condition, but increased in ischemia-reperfusion condition, and further significantly enhanced by platelets. The number of tumor metastatic foci and the density of blood vessels within metastatic foci in lung were markedly increased by tumor cell pre-adhered with platelet. The adhesion or fusion of platelet to endothelial cell mediated by platelet surface adhesion molecules, which could promote the adhesion of tumor cell with endothelial cells and the tumor metastasis.     

Mechanical properties of the extracellular matrix alter expression of smooth muscle protein LPP and its partner palladin; relationship to early atherosclerosis and vascular injury

Lipoma preferred partner (LPP) localizes to focal adhesions/dense bodies, is selectively expressed in smooth muscle cells (SMC) and enhances cell migration. SMCs cultured on denatured collagen or on a rigid substrate, up regulated expression of LPP, its partner palladin, tenascin C (TN-C), phosphorylated focal adhesion kinase (pFAK) and exhibited robust stress fibers. In an endothelial (EC)/SMC hemodynamic flow system, shear stress waveforms mimicking atheroprone flow, applied to the EC layer, significantly decreased expression of SMC LPP and palladin. They were also down regulated with TN-C, in an ApoE murine model of atherosclerosis and with oxidative stress but up regulated in an arterial injury model in response to upstream sequential changes in pFAK, Prx1 and TN-C. In conclusion, expression of LPP and palladin are modulated by a mix of mechanical cues, oxidative stress and substrate composition which translate into their up or down regulation in vessel wall injury and early atherogenesis.     

Endothelial Cell–Smooth Muscle Cell Co-Culture in a Perfusion Bioreactor System

Vascular endothelial cells (EC) are exposed to a complex biomechanical environment in vivo and are responsible for relaying important messages to the underlying tissue. EC and smooth muscle cells (SMC) communicate to regulate vascular development and function. In this work, a vascular perfusion bioreactor is used to grow tubular constructs seeded with EC and SMC under pulsatile shear stress in long-term co-culture to study the effects of EC on SMC function. SMC seeded into porous poly(glycolic acid) tubular scaffolds are cultured in the bioreactor for 25 days. Constructs are seeded with EC on day 10 or day 23 creating 2-day (short-term) or 15-day (long-term) EC and SMC co-cultures. Long-term EC–SMC co-culture significantly increases cell proliferation and downregulates collagen and proteoglycan deposition compared to short-term co-culture. After 25 days of culture, 15-day co-culture constructs have a more uniform cell distribution across the construct thickness and SMC express a more contractile phenotype compared to 2-day co-culture constructs. These data demonstrate strong interactions between SMC and EC in the bioreactor under physiologically relevant conditions. Thus, the vascular construct perfusion bioreactor is an important tool to investigate cell–cell and cell–extracellular matrix interactions in vascular cell biology and tissue engineering.     

Recellularization of biological heart valves with human vascular cells: in vitro hemocompatibility assessment

Coverage of cardiovascular bioprostheses with autologous endothelium is used for the purpose of improving blood compatibility. The aim of our study was to analyze endothelialization potential of glutaraldehyde-fixed heart valves, cellular functions of seeded endothelial cells (EC), and the impact of a two-stage seeding protocol using human vascular fibroblasts (FB) and EC from saphenous veins (HSVEC) on cellular functional properties in vitro. Adherence and morphology of adhered cells were assessed by scanning electronic microscopy and immunohistochemistry. Reproducible, complete surface coverage with EC was established on decellularized and glutaraldehyde-fixed bovine pericardium. Analyzing functional properties of cells directly adhered to biomaterial revealed nonproliferative cells, which were capable of inflammatory stimulation in terms of TNF-induced increase in interleukin-6 secretion and adhesion of inflammatory cells. Furthermore, EC showed sustained antithrombotic properties quantified by platelet adhesion onto EC and prostacyclin secretion by EC. Preseeding with vascular fibroblasts using a two-stage seeding protocol induced EC proliferation and improved inflammatory and anti-thrombotic functions. Cardiovascular biomaterials differ significantly in their potential to allow for adhesion of human EC. Successfully endothelialized biomaterial, however, revealed cellular properties which are likely to be favorable to improving performance of biomaterials. Two-stage seeding adds regenerative potential and improves cell functions of adherent EC.     

Endothelial and smooth muscle cell seeding onto processed ex vivo arterial scaffolds using 3D vascular bioreactors

Biomaterials derived from ex vivo tissues offer a viable alternative to synthetic materials for organ replacement therapies. In this study, we describe the use of a tissue engineering scaffold derived from ex vivo arterial tissue to assess vascular cell adhesion within a three-dimensional perfusion bioreactor. With the aim of maximizing seeding efficiency, five methods for endothelial cell (EC) and three independent methods for vascular smooth muscle cell (VSMC) adhesion were explored. Seeded constructs were maintained in vascular bioreactors under pulsatile flow conditions, culminating at 165 ml/min at 1.33 Hz to validate cell attachment and retention over time. Progressive modification of the seeding and flow regime protocols resulted in an increased of EC retention from 5.1 to 634 cells/mm2. Seeding VSMCs as sheets rather than cell suspensions bound and stabilized surface EC matrix fibers, resulting in multiple cell layers adhered to the scaffold with cells migrating to the medial/adventitial boundary. In conjunction with the bioscaffold, the vascular perfusion system serves as a useful tool to analyze cell adhesion and retention by allowing controlled manipulation of seeding and perfusion conditions.     

Preparation of alginic acid layers on stainless-steel substrates for biomedical applications

This study is concerned with the blood compatibility of alginic acid layers immobilized on gamma-aminopropyltriethoxysilane (gamma-APS)-grafted stainless-steel (SUS316L). The surfaces were characterized with contact angle measurement and X-ray photoelectron spectroscopy (XPS). The blood compatibility was evaluated in terms of platelet adhesion and blood clotting time. An in vitro platelet adhesion assay indicated that only a small number of platelets adhered to substrate surfaces modified with gamma-APS and subsequently with alginic acid. Moreover, alginic-acid-immobilized SUS316L substrates had little effect on the blood clotting time. This indicated that alginic-acid-immobilized SUS316L substrates do not adsorb some blood-clotting proteins or factors, or stimulate them.     

The thrombogenicity of human umbilical vein endothelial cell seeded collagen modules

Modular tissue-engineered constructs are assembled from sub-mm sized cylindrical collagen gel modules which are covered with a surface layer of human umbilical vein endothelial cells (HUVEC). The resulting construct is permeated by a network of interconnected endothelial cell lined channels to facilitate blood perfusion and nutrient delivery. This design strategy relies critically on the endothelial cells' layer behaving in a non-thrombogenic manner on the module surface and the objective here was to characterize this thrombogenicity. HUVEC prolonged clotting times in whole blood-module mixtures, and enabled slightly heparinized whole blood perfusion of an assembled modular construct in vitro with no increase in platelet loss compared to background levels. Flow cytometry and scanning electron microscopy indicated that HUVEC seeded modules reduced platelet activation and deposition but not leukocyte activation, compared to collagen only modules. Plasma recalcification times on non-stimulated HUVEC were longer compared to stimulated HUVEC but not different than that on collagen only module films and were not prolonged by incubation with a tissue factor blocking antibody. Together these data suggest that a functional non-thrombogenic layer of EC was generated on the module surface and that this layer should be sufficient to maintain continuous blood flow through an engineered modular tissue. In/ex vivo studies are warranted to confirm this conclusion.     

Distinct extracellular matrix microenvironments of progenitor and carotid endothelial cells

Endothelial cells (ECs) produce and maintain the local extracellular matrix (ECM), a critical function that contributes to EC and blood vessel health. This function is also crucial to vascular tissue engineering, where endothelialization of vascular constructs require a cell source that readily produces and maintains ECM. In this study, baboon endothelial progenitor cell (EPC) deposition of ECM (laminin, collagen IV, and fibronectin) was characterized and compared to mature carotid ECs, evaluated in both elongated and cobblestone morphologies typically found in vivo. Microfluidic micropatterning was used to create 15-microm wide adhesive lanes with 45-microm spacing to reproduce the elongated EC morphology without the influence of external forces. Both EPCs and ECs elongated on micropatterned lanes had aligned actin cytoskeleton and readily deposited ECM. EPCs deposited and remodeled the ECM to a greater extent than ECs. Since a readily produced ECM can improve graft patency, EPCs are an advantageous cell source for endothelializing vascular constructs. Furthermore, EC deposition of ECM was dependent on cell morphology, where elongated ECs deposited more collagen IV and less fibronectin compared to matched cobblestone controls. Thus micropatterned surfaces controlled EC shape and ECM deposition, which ultimately has implications for the design of tissue-engineered vascular constructs.     

In vivo performance of dual ligand augmented endothelialized expanded polytetrafluoroethylene vascular grafts

In this study, we examined combinations of three approaches to improve the adhesion of endothelial cells (EC) onto expanded polytetrafluoroethylene (ePTFE) vascular grafts placed at the femoral artery of rats: (1) high-affinity receptor-ligand binding of RGD-streptavidin (SA) and biotin to supplement integrin-mediated EC adhesion; (2) cell sodding to pressurize the seeded EC into the interstices of the ePTFE grafts; and (3) longer postseeding attachment time from 1 to 24 h prior to implantation. An in vitro system, which accounts for cell loss due to both graft handling and shear stress, was designed to optimize conditions for in vivo experiments. Results suggest that longer in vitro attachment time enabled the adherent EC to endure mechanical stresses by forming strong adhesions to the underlying extracellular matrix substrates; cell sodding helped to retain the adherent EC by physically docking the cells against the graft interstices; and the SA-biotin interaction enhanced the early attachment of EC but did not lead to better cell retention or reduced surface coverage of blood clot in the current study. Mechanical manipulation of cells during implantation is a limiting factor in maintaining a confluent EC layer on synthetic vascular grafts.     

Design of scaffolds for blood vessel tissue engineering using a multi-layering electrospinning technique

Aiming to develop a scaffold architecture mimicking morphological and mechanically that of a blood vessel, a sequential multi-layering electrospinning (ME) was performed on a rotating mandrel-type collector. A bi-layered tubular scaffold composed of a stiff and oriented PLA outside fibrous layer and a pliable and randomly oriented PCL fibrous inner layer (PLA/PCL) was fabricated. Control over the level of fibre orientation of the different layers was achieved through the rotation speed of the collector. The structural and mechanical properties of the scaffolds were examined using scanning electron microscopy (SEM) and tensile testing. To assess their capability to support cell attachment, proliferation and migration, 3T3 mouse fibroblasts and later human venous myofibroblasts (HVS) were cultured, expanded and seeded on the scaffolds. In both cases, the cell-polymer constructs were cultured under static conditions for up to 4 weeks. Environmental-scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), histological examination and biochemical assays for cell proliferation (DNA) and extracellular matrix production (collagen and glycosaminoglycans) were performed. The findings suggest the feasibility of ME to design scaffolds with a hierarchical organization through a layer-by-layer process and control over fibre orientation. The resulting scaffolds achieved the desirable levels of pliability (elastic up to 10% strain) and proved to be capable to promote cell growth and proliferation. The electrospun PLA/PCL bi-layered tube presents appropriate characteristics to be considered a candidate scaffold for blood vessel tissue engineering.     

Regulation and function of an activation-dependent epitope of the beta 1 integrins in vascular cells after balloon injury in baboon arteries and in vitro.

Migration and proliferation of endothelial cells (ECs) and smooth muscle cells (SMCs) contribute to the response to injury in damaged and atherosclerotic vessels. These events might be regulated by cellular interactions with extracellular matrix through the expression and activation of integrins. To study the functions of beta 1 integrins in the vessel wall, we used monoclonal antibody (MAb) 15/7, which recognizes an activation epitope of beta 1 integrin subunits, and MAb 8A2, which induces a high affinity form of beta 1 integrins recognized by MAb 15/7. Immunohistochemical analyses were done on samples of normal baboon saphenous arteries and from arteries subjected to balloon injury. EC and SMC expressed the activation epitope of beta 1 integrin in uninjured arteries. By contrast, in balloon-injured arteries 6 weeks after injury, regenerating EC did not express the activation epitope, and there was no decrease in the expression of total beta 1 integrin, whereas SMC migrating into the intima exhibited decreased expression of the total and activated beta 1 integrin. Flow cytometer analysis of cultured cells indicated that baboon EC and SMC weakly express the activation epitope of beta 1 integrin. Next, we determined by utilizing MAb 8A2 the effects of increased expression of activation epitope of beta 1 integrin on the functions of SMC and EC. The activation of beta 1 integrins on SMC induced by MAb 8A2 enhanced SMC adhesion and suppressed SMC migration in a Boyden chamber assay. SMC proliferation was inhibited by MAb 8A2 dose-dependently. Similarly, MAb 8A2-induced activation of beta 1 integrins on EC suppressed EC migration into a wound. However, MAb 8A2 did not affect the basic fibroblast growth factor-induced proliferation of EC, although it blocked the decrease in EC number caused by the removal of basic fibroblast growth factor. These results suggest that activation of beta 1 integrins in vascular cells is regulated in a cell-type dependent manner and plays an important role in modulating vascular cell functions.     

去细胞肌肉生物支架与人脐带间充质干细胞的相容性

背景：去细胞肌肉生物支架联合人脐带间充质干细胞移植将是治疗脊髓损伤的一项重要措施。但两者是否具有良好的相容性,人脐带间充质干细胞能否在去细胞肌肉生物支架中长期存活并均匀分布,尚未得到证实。 目的：观察大鼠去细胞肌肉生物支架与人脐带间充质干细胞的相容性。 方法：改良化学法制备大鼠去细胞肌肉生物支架,将第3代人脐带间充质干细胞Hoechest33342荧光标记后分为3组进行实验,细胞+支架组、细胞+支架大鼠体内组和单纯细胞组。分别应用苏木精-伊红、Masson染色方法观察去细胞肌肉生物支架的组织形态,以荧光倒置相差显微镜和扫描电镜观察人脐带间充质干细胞的吸附和生长情况。 结果与结论：人脐带间充质干细胞与去细胞肌肉生物支架充分附着,生长增殖活跃,细胞在支架内分布均匀。细胞+支架体内组与细胞+支架组相比在移植后1-7 d人脐带间充质干细胞数量差异无显著性意义(P > 0.05),在移植14 d细胞+支架体内组人脐带间充质干细胞数量大于细胞+支架组(P < 0.05)。提示去细胞肌肉生物支架与人脐带间充质干细胞有较好的相容性,体内环境更有利于细胞增殖和两者融合。     

Resident cell lineages are preserved in pulmonary vascular remodeling

Pulmonary vascular remodeling is the main pathological hallmark of pulmonary hypertension disease. We undertook a comprehensive and multilevel approach to investigate the origin of smooth muscle actin‐expressing cells in remodeled vessels. Transgenic mice that allow for specific, inducible, and permanent labeling of endothelial (Cdh5‐tdTomato), smooth muscle (Acta2‐, Myh11‐tdTomato), pericyte (Cspg4‐tdTomato), and fibroblast (Pdgfra‐tdTomato) lineages were used to delineate the cellular origins of pulmonary vascular remodeling. Mapping the fate of major lung resident cell types revealed smooth muscle cells (SMCs) as the predominant source of cells that populate remodeled pulmonary vessels in chronic hypoxia and allergen‐induced murine models. Combining in vivo cell type‐specific, time‐controlled labeling of proliferating cells with a pulmonary artery phenotypic explant assay, we identified proliferation of SMCs as an underlying remodeling pathomechanism. Multicolor immunofluorescence analysis showed a preserved pattern of cell type marker localization in murine and human pulmonary arteries, in both donors and idiopathic pulmonary arterial hypertension (IPAH) patients. Whilst neural glial antigen 2 (chondroitin sulfate proteoglycan 4) labeled mostly vascular supportive cells with partial overlap with SMC markers, PDGFRα‐expressing cells were observed in the perivascular compartment. The luminal vessel side was lined by a single cell layer expressing endothelial markers followed by an adjacent and distinct layer defined by SMC marker expression and pronounced thickening in remodeled vessels. Quantitative flow cytometric analysis of single cell digests of diverse pulmonary artery layers showed the preserved separation into two discrete cell populations expressing either endothelial cell (EC) or SMC markers in human remodeled vessels. Additionally, we found no evidence of overlap between EC and SMC ultrastructural characteristics using electron microscopy in either donor or IPAH arteries. Lineage‐specific marker expression profiles are retained during pulmonary vascular remodeling without any indication of cell type conversion. The expansion of resident SMCs is the major underlying and evolutionarily conserved paradigm of pulmonary vascular disease pathogenesis. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.     

In vitro studies of thromboresistance: the role of prostacyclin (PGI2) in platelet adhesion to cultured normal and virally transformed human vascular endothelial cells

Circulating blood platelets normally do not adhere to, or aggregate on, the vascular endothelial lining. We have developed an in vitro model system to study the mechanisms of endothelial resistance to platelet adhesion, and to determine the role of prostacyclin (PGI2) in this process. This system combines scanning electron microscopy and measurement of bound (3H)-adenine-labeled platelets to examine platelet adhesion to primary cultures of human endothelial cells, which generate PGI2-like activity, and to virally transformed endothelial cells, which lack this activity. Under basal conditions primary cultures bound less than one platelet per cell (228 +/- 8 c.p.m. per 10(4) cells, mean +/- standard error of the mean). Inhibition of endothelial PGI2 production by 50 microM aspirin or 2.8 microM indomethacin did not result in a significant change in platelet adherence. Stimulating prostaglandin production with arachidonic acid, or adding exogenous PGI2 did not depress platelet adhesion below the basal levels observed with untreated cultures. In contrast ot primary cultures, transformed endothelium showed markedly increased platelet adherence (3,993 +/- 194 c.p.m. per 10(4), mean +/- standard error of the mean), in the form of single platelets and clusters of two to five nonaggregated platelets. Although exogenous PGI2 was effective in hibiting platelet adherence to these transformed cells, even pharmacologic doses (1 microgram. per ml.) did not depress adhesion to the basal levels associated with normal cells. These results suggest that endothelial properties essential to blood compatibility are altered by viral transformation, and further, that generation of PGI2 by normal endothelium is not the key factor which prevents platelet adherence to the intact vessel wall.     

Multiscale Systems Biology and Physics of Thrombosis Under Flow

Blood clotting under hemodynamic conditions involves numerous multiscale interactions from the molecular scale to macroscopic vessel and systemic circulation scales. Transmission of shear forces to platelet receptors such as GPIbα, P-selectin, α(2)β(1), and α(2b)β(3) controls adhesion dynamics. These forces also drive membrane tether formation, cellular deformation, and mechanosignaling in blood cells. Blood flow results in red blood cell (RBC) drift towards the center of the vessel along with a near-wall plasma layer enriched with platelets. RBC motions also dramatically enhance platelet dispersion. Trajectories of individual platelets near a thrombotic deposit dictate capture-activation-arrest dynamics as these newly arriving platelets are exposed to chemical gradients of ADP, thromboxane, and thrombin within a micron-scale boundary layer formed around the deposit. If shear forces are sufficiently elevated (>50?dyne/cm(2)), the largest polymers of von Willebrand Factor may elongate with concomitant shear-induced platelet activation. Finally, thrombin generation enhances platelet recruitment and clot strength via fibrin polymerization. By combination of coarse-graining, continuum, and stochastic algorithms, the numerical simulation of the growth rate, composition, and occlusive/embolic potential of a thrombus now spans multiscale phenomena. These simulations accommodate particular flow geometries, blood phenotype, pharmacological regimen, and reactive surfaces to help predict disease risk or response to therapy.     

桡神经臂部血供的微血管构筑

目的为临床工作中修复桡神经长段缺损及利用该神经修复其他神经损伤提供形态学基础。方法对35侧经腋动脉灌注带色乳胶的成人上肢标本,组织学切片观察供给桡神经的微血管构筑、营养动脉的外径、神经外膜、神经束组间、神经束间以及神经束内血管层动脉内径,在显微镜下观察神经干内不同水平的血管内径和血管网的分布及吻合情况,显微镜下进行追踪观察并用测微尺计测。结果镜下所见的血管内径相差较大,在臂部桡神经束组间血管层中,上、中、下各1/3段动脉平均内径(μm)分别为31.03±1.26,29.88±1.60和35.70±1.87。中、下1/3段动脉平均内经相比较,两者无显著差异(t=1.43,P>0.05)。在臂部桡神经外膜血管层中,以中、下1/3段动脉内径较大,与上1/3段动脉平均内经相比较,差异非常显著(t=2.67,P<0.01)。结论在光镜下,桡神经微血管构筑可分4层,各层血管内径在神经的不同部位可发生一定的变化,血管集中区域的动脉外径较大时,它所在部位的外膜、束组间、束间甚至束内的血管内径都有增大的趋势。桡神经纵切片中,外膜血管网密度高于束内血管网密度。     

Antithrombogenic investigation of surface energy and optical bandgap and hemocompatibility mechanism of Ti(Ta(+5))O2 thin films

Recent improvements in the antithrombogenic properties of blood contacting biomaterials permit a hybrid design of layers for biomedical applications such as artificial heart valves and stents. Using magnetron sputtering and thermal oxidation, titanium oxide thin films containing tantalum. Ti(Ta(+5))O2, are fabricated to meet the challenge of enhanced hemocompatibility. The blood compatibility is evaluated in vitro by clotting time and platelet adhesion measurement, and in vivo experiments are also conducted. The Ti(Ta(+5))O2 films exhibit attractive blood compatibility exceeding that of low isotropic pyrolytic carbon. Physical properties such as surface energy and semiconductivity are found to play important roles. Our calculated results reveal that the smaller surface force gamma(s) of the film and the smaller blood film interfacial tension gamma(c,blood) are partially responsible for the enhancement of the blood compatibility. Based on the optical bandgap model, the film possesses better hemocompatibility because its optical bandgap of 3.2 eV is wider than that of fibrinogen having a bandgap of 1.8 eV. These factors result in thinner protein layers on the film surface, less protein denaturing, and overall excellent antithrombogenic properties.     

基于连笔直写的微结构血管支架体外测评

目的 评价基于连笔直写的生命体微结构成形技术制备的管状支架的力学性能及其生物相容性.方法 对该血管支架采用径向顺应性、缝合强度、爆破压力等力学性能检测;通过溶血率、体外动态凝血实验、血小板黏附实验进行血液相容性的分析;采用细胞培养MTT法及细胞形态学观察方法,研究其细胞相容性.结果 血管支架的径向顺应性为（4.03±0.56）%/100mmHg,缝合强度为（204.5±72.1）N/cm2,爆破压力约为（102±8）kPa;支架的溶血率为1.75%,小于ISO规定的5%;在体外动态凝血实验中,血管支架的抗凝血性能显著优于对照组载玻片（P＜0.05）,而且扫描电镜观察到血小板黏附较少,显示出该血管支架具有良好抗凝血性能;MTT比色法结果显示其细胞毒性为0～1级;细胞形态学观察显示L929细胞在该血管支架膜片的浸提液中呈梭形或三角形,贴壁良好.结论 该血管支架具有良好的力学性能、血液相容性和细胞相容性,可以满足组织工程血管支架的要求.