PDS血管外支架体外毒性和体内相容性的实验研究

目的观察血管外支架材料聚对二氧环己酮（PDS）的体外毒性和体内生物相容性。方法按照医疗器械生物学评价标准，采用体外细胞培养法、MTT法进行PDS体外细胞毒性试验，并进行体内植入降解实验。结果PDS网状支架材料对细胞形态、生长代谢和增殖不构成损害；PDS在体内12周左右开始加速降解，24周完全降解吸收，炎性反应也减退消失，材料区域被新生纤维组织取代，降解过程中未对周围组织产生不良刺激。结论PDS支架材料元细胞毒性，组织反应轻，可满足体内植入的要求。     

生物可降解血管内支架研究现状

生物可降解血管内支架由可吸收材料制成,在短期内能支撑血管,达到血运重建的目的,最终能在体内降解为无毒产物,随机体正常代谢排出体外.生物可降解支架可以避免金属永久支架引起的并发症,具有较好的生物相容性.从上世纪80年代生物可降解支架开始用于临床以来,无论在支架材料选择,还是支架制作工艺上,都有较大的发展,本文介绍近年来生物可降解血管内支架的研究现状.     

生物可降解血管内支架研究现状

生物可降解血管内支架由可吸收材料制成,在短期内能支撑血管,达到血运重建的目的,最终能在体内降解为无毒产物,随机体正常代谢排出体外。生物可降解支架可以避免金属永久支架引起的并发症,具有较好的生物相容性。从上世纪80年代生物可降解支架开始用于临床以来,无论在支架材料选择,还是支架制作工艺上,都有较大的发展,本文介绍近年来生物可降解血管内支架的研究现状。     

肌瓣内置壳聚糖管修复颈段食管部分缺损的可行性研究

目的探讨肌瓣内置壳聚糖管状支架补颈段食管部分缺损的可行性。方法取21只大耳白兔,制成颈段食管部分缺损模型,破损处内置壳聚糖管状支架,外附肌瓣修补。观察术后动物体质量变化;分别于术后第4、8、12周各处死动物3只,肉眼及光学显微镜下观察食管缺损修复情况;术后第16周行食管钡透,观察食管狭窄及蠕动情况。结果术后动物存活18只,第4周肌瓣组织愈合良好,壳聚糖管未吸收,光镜下见炎性反应;第8周聚糖管部分吸收,肌瓣血运良好,无纤维组织增生;第12周壳聚糖管完全吸收,肌瓣内表面黏膜再生,无管腔狭窄。术后第16周,钡透见食管通畅、无狭窄,蠕动弱。结论肌瓣内置壳聚糖管状支架修补颈段食管部分缺损具有可行性。     

生物可降解血管内支架：希望和挑战

生物可降解血管内支架(BDS)具有较好的生物相容性和可吸收性,能在短期内支撑血管,达到血运重建的目的.由于完成使命后可在体内降解,生物可降解支架可以避免金属永久支架引起的并发症.目前的研制主要包括可降解聚合物材料、金属镁和铁.上世纪80年代BDS已经进入临床且取得了一定的效果,它使血管成形术向前跨进了一步.目前的生物可降解血管内支架存在着一些缺陷,需要进一步改进和验证.     

控释双生长因子海藻酸钠水凝胶载体的制备及检测

目的 制备控释双生长因子海藻酸钠水凝胶载体,并检测其理化性能.方法 采用氧化及钴60辐照对海藻酸钠进行修饰,制备控释双生长因子海藻酸钠水凝胶载体.将无针注射器中海藻酸钠水凝胶打入24孔培养板中,通过测定水凝胶的干重损失检测控释双生长因子海藻酸钠水凝胶的体外降解.用无针注射器于18只兔心肌组织喷射100 μl双生长因子海藻酸钠水凝胶,分别于各时间点取心肌组织,进行HE染色,观察海藻酸钠水凝胶的体内降解情况.采用MTT法进行控释双生长因子海藻酸钠水凝胶的细胞毒性分析.结果 体外降解实验中,控释双生长因子海藻酸钠水凝胶显示了相对较快地降解,第1周大约降解50%,3 w后几乎降解完全.体内降解实验显示,心肌组织中控释双生长因子海藻酸钠水凝胶逐渐减少,5 w后,在心肌组织中几乎没有观察到水凝胶的片段.控释双生长因子海藻酸钠水凝胶对细胞活性无明显影响.结论 成功制备了控释双生长因子海藻酸钠水凝胶载体,具有较好的降解性能及安全性,它可以作为具有控制释放生长因子能力的生物载体材料,为后续实验提供基础.     

新型生物全降解药物释放支架对小型实验猪冠状动脉内膜的影响

目的探讨由融入无定型磷酸钙纳米颗粒构建的新型生物全降解支架置入小型实验猪后对损伤血管内膜的影响。方法将10只正常小型实验猪随机分为实验组(即融入无定型磷酸钙纳米颗粒构建的新型生物全降解支架组,5只)和对照组(普通聚左旋乳酸支架组,5只),选取合适的冠状动脉随机置入1枚普通聚左旋乳酸支架或新型生物全降解支架。分别于术前和术后28 d取股动脉血采用免疫吸附法行C反应蛋白(CRP)浓度检测。支架置入术后4周所有实验动物行冠状动脉造影复查后,处死动物并取支架置入部位血管固定并行苏木精-伊红染色,观察炎性细胞及炎症积分、内膜增生情况、免疫组织化学核因子(NF)-κB与α-平滑肌肌动蛋白(α-SM-actin)分析。结果实验组与对照组实验动物术后对动物觅食、活动等一般情况无影响。免疫吸附法检测血液CRP浓度显示,两组术前与术后28 d比较差异均无统计学意义,术后两组CRP浓度比较差异无统计学意义。实验组支架置入部位血管炎症细胞(27.32±1.50比54.12±3.99,P<0.05)及炎症积分(1.04±0.17比2.08±0.23,P<0.05)均明显低于对照组。实验组内膜增生面积增加、管腔面积减少、面积狭窄百分比升高及支架置入部位α-SM-actin平均光密度值升高,但差异均无统计学意义。结论新型生物全降解支架具有良好的组织相容性,其于冠状动脉置入后支架部位炎症较普通生物降解支架明显降低,未引起血管平滑肌细胞过度增殖亦不会导致内膜明显增生。     

明胶-壳聚糖复合神经营养素3神经支架材料的构建及其生物相容性检测

目的构建明胶—壳聚糖复合神经营养素3神经支架材料,并检测其生物相容性。方法混合明胶、壳聚糖溶液后加入微量神经营养素3,将混浊液注模成型后冷淋干燥制备明胶—壳聚糖复合神经营养素3神经支架材料,利用扫描电子显微镜观察支架材料形态,液体代替法测算孔隙率。提取明胶—壳聚糖复合神经营养素3神经支架材料浸提液,观察其对神经干细胞活性的影响及对全反式维甲酸预诱导的神经干细胞分化的影响,并采用膜片钳技术检测诱导分化前后细胞的电生理特性。结果明胶—壳聚糖复合神经营养素3神经支架材料内径为(267.0±13.8)μm,孔隙率为90.0%。神经干细胞在支架材料上生长良好,在全反式维甲酸诱导下形态向神经元样细胞改变,并初步表现出神经元间突触连接的结构,且诱导分化的神经元样细胞初步具备神经元细胞的电生理特性。结论成功构建了明胶—壳聚糖复合神经营养素3神经支架材料,其与神经干细胞之间的生物相容性良好。     

生物可降解镁合金支架的目前研究和展望

1977年进行的经皮冠状动脉腔内成形术开启了冠心病介入治疗的新时代.随后经历了金属裸支架、药物洗脱支架和生物可降解支架.聚合物材料可降解支架因径向支撑力不足,降解产物对血管壁产生较持续的炎症等问题,并非完美.近年来发现可降解镁合金具有良好的生物相容性.基础实验和临床试验证实了其安全性和持久性.现论述可降解镁合金支架的优...     

转化生长因子β1缓释微球对体外P3/4HB无纺支架细胞生长的影响

目的:研究转化生长因子β2(TGF-β1)壳聚糖缓释微球对体外3-羟基丁酸酯-co-4-羟基丁酸酯(P3/4HB)无纺支架培养肌成纤维细胞的作用.方法:静电纺丝法制备P3/4HB无纺支架,接种大鼠肌成纤维细胞.在实验组培养基中分别加入TGF-β1.缓释微球和TGF-β1,体外培养1周后行扫描电镜观察,检测羟脯氨酸和DNA含量;并用ELISA法动态检测TGF-β1缓释微球缓释效果.结果:TGF-β1可从缓释微球中缓慢释放,1周内微球释放率为40.6%.与对照组比较,实验组细胞生长紧密,羟脯氨酸及DNA含量增高.结论:TGF-β1壳聚糖缓释微球可在体外稳定释放,并具有生物学活性;其运用于P3/4HB无纺支架,可促进细胞增殖和胶原合成,为研究为制备携带壳聚糖TGF-β1缓释微球的组织工程复合支架打下了良好的基础.     

The Characterization of Scaffolds Based on Dialdehyde Chitosan/Hyaluronic Acid

In this work, two-component dialdehyde chitosan/hyaluronic acid scaffolds were developed and characterized. Dialdehyde chitosan was obtained by one-step synthesis with chitosan and sodium periodate. Three-dimensional scaffolds were prepared by the lyophilization method. Fourier transform infrared spectroscopy (FTIR) was used to observe the chemical structure of scaffolds and scanning electron microscopy (SEM) imaging was done to assess the microstructure of resultant materials. Thermal analysis, mechanical properties measurements, density, porosity and water content measurements were used to characterize physicochemical properties of dialdehyde chitosan/hyaluronic acid 3D materials. Additionally, human epidermal keratinocytes (NHEK), dermal fibroblasts (NHDF) and human melanoma cells (A375 and G-361) were used to evaluate cell viability in the presence of subjected scaffolds. It was found that scaffolds were characterized by a porous structure with interconnected pores. The scaffold composition has an influence on physicochemical properties, such as mechanical strength, thermal resistance, porosity and water content. There were no significant differences between cell viability proliferation of all scaffolds, and this observation was visible for all subjected cell lines.     

Biomaterials with Potential Use in Bone Tissue Regeneration—Collagen/Chitosan/Silk Fibroin Scaffolds Cross-Linked by EDC/NHS

Blending of different biopolymers, e.g., collagen, chitosan, silk fibroin and cross-linking modifications of these mixtures can lead to new materials with improved physico-chemical properties, compared to single-component scaffolds. Three-dimensional scaffolds based on three-component mixtures of silk fibroin, collagen and chitosan, chemically cross-linked, were prepared and their physico-chemical and biological properties were evaluated. A mixture of EDC (N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride) and NHS (N-hydroxysuccinimide) was used as a cross-linking agent. FTIR was used to observe the position of the peaks characteristic for collagen, chitosan and silk fibroin. The following properties depending on the scaffold structure were studied: swelling behavior, liquid uptake, moisture content, porosity, density, and mechanical parameters. Scanning Electron Microscopy imaging was performed. Additionally, the biological properties of these materials were assessed, by metabolic activity assay. The results showed that the three-component mixtures, cross-linked by EDC/NHS and prepared by lyophilization method, presented porous structures. They were characterized by a high swelling degree. The composition of scaffolds has an influence on mechanical properties. All of the studied materials were cytocompatible with MG-63 osteoblast-like cells.     

壳聚糖和透明质酸纳米聚电解质复合物吸附动脉粥样硬化特异抗体CD47的合成及体内外靶向实验

目的研究壳聚糖和透明质酸聚电解质复合物(PEC)纳米颗粒在生理盐水中的稳定浓度和物理化学参数对靶向抗体CD47有效吸附的影响以及合成的纳米载体对于血管内皮细胞的体外靶向性。方法壳聚糖(CS)作为聚阳离子与透明质酸(HA)(作为聚阴离子)发生电荷中和,合成壳聚糖和透明质酸聚电解质复合物纳米粒子。一模型抗体——动脉粥样硬化靶向抗体CD47在水或PBS溶液中,与纳米颗粒作用4 h后,定量吸附在CS-HA纳米颗粒表面。将合成的纳米载体体内外与血管内皮细胞及动脉粥样斑块相互作用,研究其靶向吸附作用。结果络合过程和胶体的物理化学性质受到外部因素的影响,如电荷混合比和聚合物浓度等参数。通过上述原理合成了非化学计量的CS-HA纳米胶体,在水或PBS(pH 7.4)溶液中保持稳定1个多月。扫描电镜检测其形貌特征。CS-HA/CD47抗体纳米颗粒平均粒径在375～620 nm之间,Zeta电位为正。CD47抗体靶向的纳米载体可在体外有效吸附到血管内皮细胞及动脉粥样斑块的表面。结论成功合成了CS-HA/CD47抗体纳米颗粒,该靶向纳米载体在体外可有效吸附到血管内皮细胞株及动脉粥样斑块的表面,是对动脉粥样硬化靶向给药具有应用前景的有效纳米载体。     

Synthesis and Characterization of Electrospun Composite Scaffolds Based on Chitosan-Carboxylated Graphene Oxide with Potential Biomedical Applications

This research study reports the development of chitosan/carboxylated graphene oxide (CS/GO-COOH) composite scaffolds with nanofibrous architecture using the electrospinning method. The concept of designed composite fibrous material is based on bringing together the biological properties of CS, mechanical, electrical, and biological characteristics of GO-COOH with the versatility and efficiency of ultra-modern electrospinning techniques. Three different concentrations of GO-COOH were added into a chitosan (CS)-poly(ethylene oxide) (PEO) solution (the ratio between CS/PEO was 3/7 (w/w)) and were used in the synthesis process of composite scaffolds. The effect of GO-COOH concentration on the spinnability, morphological and mechanical features, wettability, and biological properties of engineered fibrous scaffolds was thoroughly investigated. FTIR results revealed the non-covalent and covalent interactions that could take place between the system’s components. The SEM micrographs highlighted the nanofibrous architecture of scaffolds, and the presence of GO-COOH sheets along the composite CS/GO-COOH nanofibers. The size distribution graphs showed a decreasing trend in the mean diameter of composite nanofibers with the increase in GO-COOH content, from 141.40 nm for CS/PG 0.1% to 119.88 nm for CS/PG 0.5%. The dispersion of GO-COOH led to composite scaffolds with increased elasticity; the Young’s modulus of CS/PG 0.5% (84 ± 4.71 MPa) was 7.5-fold lower as compared to CS/PEO (662 ± 15.18 MPa, p < 0.0001). Contact angle measurements showed that both GO-COOH content and crosslinking step influenced the surface wettability of scaffolds, leading to materials with ~1.25-fold higher hydrophobicity. The in vitro cytocompatibility assessment showed that the designed nanofibrous scaffolds showed a reasonable cellular proliferation level after 72 h of contact with the fibroblast cells.     

Deacetylation of Chitosan: Material Characterization and in vitro Evaluation via Albumin Adsorption and Pre-Osteoblastic Cell Cultures

Degree of deacetylation (DDA) and molecular weight (MW) of chitosans are important to their physical and biological properties. In this study, two chitosans, HS (DDA = 73.3%) and AT (DDA = 76.8%), were deacetylated with 45% sodium hydroxide under nitrogen atmosphere at 80 °C or 90 °C for up to 120 min, to obtain two series of chitosans. The polymers produced were characterized for MW by gel permeation chromatography, DDA by titration and UV-vis methods, and crystallinity, hydrophilicity and thermal stability by X-ray diffraction, water contact angle and differential scanning calorimetry respectively. Films, made by solution casting in dilute acetic acid at ambient conditions, were evaluated for biological activity by albumin adsorption and the attachment and growth of a pre-osteoblast cell line. Chitosans with between 80–93% DDA’s (based on titration) were reproducibly obtained. Even though deacetylation under nitrogen was supposed to limit chain degradation during decetylation, MW decreased (by maximum of 37.4% of HS and 63.0% for AT) with increasing deacetylation reaction time and temperature. Crystallinity and decomposition temperature increased and water contact angles decreased with processing to increase DDA. Significantly less albumin was absorbed on films made with 93% DDA chitosans as compared with the original materials and the AT chitosans absorbed less than the HS chitosans. The cells on higher DDA chitosan films grew faster than those on lower DDA films. In conclusion, processing conditions increased DDA and influenced physicochemical and biological properties. However, additional studies are needed to unambiguously determine the influence of DDA or MW on in vitro and in vivo performance of chitosan materials for bone/implant applications.     

Chitosan Edible Films Enhanced with Pomegranate Peel Extract: Study on Physical,Biological, Thermal,and Barrier Properties

In the present study, pomegranate peel extract was used as a reinforcing agent in developing chitosan-based edible film. Different concentrations (0.2 g/mL, 0.4 g/mL, 0.6 g/mL, 0.8 g/mL, and 1.0 g/mL) of pomegranate peel extract were incorporated in chitosan-based edible film. A neat chitosan film was used as a control. This work covers the effect of pomegranate peel extract on the physical, biological, mechanical, thermal, and barrier properties of enriched chitosan-based edible film. The results showed that the thickness (0.142–0.159 mm), tensile strength (32.45–35.23 MPa), moisture (11.23–15.28%), opacity (0.039–0.061%), water (1.32–1.60 g·mm/m²), gas barrier properties (93.81–103.45 meq/kg), phenolic content (5.75–32.41 mg/g), and antioxidant activity (23.13–76.54%) of the films increased with increasing volume fraction of pomegranate peel extract. A higher concentration of incorporated pomegranate peel extracts significantly (p < 0.05) reduced the thermal stability of the film, along with its transparency, solubility, swelling, and color. This work revealed that the incorporation of a higher portion of pomegranate peel extract in chitosan film holds significant (p < 0.05) potential for the increase in biological activities of such films in terms of antioxidant and antimicrobial behavior. The properties of pomegranate peel extract-enriched chitosan films could be an excellent cure for free radicals, whereas they could also inhibit the growth of the foodborne pathogens during the processing and preservation of the food. Further studies are needed for the application of pomegranate peel extract-enriched edible films on food products such as fruits and vegetables in order to extend their storage life and improve the quality and safety of preserved food products.     

Starch Solutions Prepared under Different Conditions as Modifiers of Chitosan/Poly(aspartic acid)-Based Hydrogels

Recently, there has been great interest in the application of polysaccharides in the preparation of diverse biomaterials which result from their biocompatibility, biodegradability and biological activity. In this work, the investigations on chitosan/poly(aspartic acid)-based hydrogels modified with starch were described. Firstly, a series of hydrogel matrices was prepared and investigated to characterize their swelling properties, structure via FT-IR spectroscopy, elasticity and tensile strength using the Brookfield texture analyzer as well as their impact on simulated physiological liquids. Hydrogels consisting of chitosan and poly(aspartic acid) in a 2:1 volume ratio were elastic (9% elongation), did not degrade after 30-day incubation in simulated physiological liquids, exhibited a relative biocompatibility towards these liquids and similar swelling in each absorbed medium. This hydrogel matrix was modified with starch wherein two of its form were applied—a solution obtained at an elevated temperature and a suspension obtained at room temperature. Hydrogels modified with hot starch solution showed higher sorption that unmodified materials. This was probably due to the higher starch inclusion (i.e., a larger number of hydrophilic groups able to interact with the adsorbed liquid) when this polysaccharide was given in the form of a hot solution. Hydrogels modified with a cold starch suspension had visible heterogeneous inequalities on their surfaces and this modification led to the obtainment materials with unrepeatable structures which made the analysis of their properties difficult and may have led to misleading conclusions.     

Solid-phase synthesis and chemical space analysis of a 190-membered alkaloid/terpenoid-like library

Alkaloid and terpenoid natural products display an extensive array of chemical frameworks and biological activities. However such scaffolds remain underrepresented in current screening collections and are, thus, attractive targets for the synthesis of natural product-based libraries that access underexploited regions of chemical space. Recently, we reported a systematic approach to the stereoselective synthesis of multiple alkaloid/terpenoid-like scaffolds using transition metal-mediated cycloaddition and cyclization reactions of enyne and diyne substrates assembled on a tert-butylsulfinamide lynchpin. We report herein the synthesis of a 190-membered library of alkaloid/terpenoid-like molecules using this synthetic approach. Translation to solid-phase synthesis was facilitated by the use of a tert-butyldiarylsilyl (TBDAS) linker that closely mimics the tert-butyldiphenysilyl protecting group used in the original solution-phase route development work. Unexpected differences in stereoselectivity and regioselectivity were observed in some reactions when carried out on solid support. Further, the sulfinamide moiety could be hydrolyzed or oxidized efficiently without compromising the TBDAS linker to provide additional amine and sulfonamide functionalities. Principal component analysis of the structural and physicochemical properties of these molecules confirmed that they access regions of chemical space that overlap with bona fide natural products and are distinct from areas addressed by conventional synthetic drugs and drug-like molecules. The influences of scaffolds and substituents were also evaluated, with both found to have significant impacts on location in chemical space and three-dimensional shape. Broad biological evaluation of this library will provide valuable insights into the abilities of natural product-based libraries to access similarly underexploited regions of biological space.     

Understanding Electrodeposition of Chitosan–Hydroxyapatite Structures for Regeneration of Tubular-Shaped Tissues and Organs

Tubular-shaped hydrogel structures were obtained in the process of cathodic electrodeposition from a chitosan–hydroxyapatite solution carried out in a cylindrical geometry. The impact of the initial concentration of solution components (i.e., chitosan, hydroxyapatite, and lactic acid) and process parameters (i.e., time and voltage) on the mass and structural properties of deposit was examined. Commercially available chitosan differs in average molecular weight and deacetylation degree; therefore, these parameters were also studied. The application of Fourier-transform infrared spectroscopy, scanning electron microscopy, and time-of-flight secondary ion mass spectrometry allowed obtaining fundamental information about the type of bonds and interactions created in electrodeposited structures. Biocompatible tubular implants are highly desired in the field of regeneration or replacement of tubular-shaped tissues and organs; therefore, the possibility of obtaining deposits with the desired structural properties is highly anticipated.