Comparative study of three vascular grafts produced by electrospinning in vitro and in vivo
И. В. ПоповаAlena O. StepanovaDavid SergeevichevА. Е. АкуловИ. С. ЗахароваEvgeny PokushalovPavel P. LaktionovА. А. Карпенко
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Objective. The study focused on the production and evaluation of small-diameter vascular grafts (less than 6 mm) by using an electrospinning approach. Methods. The protocols of vascular grafts (VG) to be produced from the solutions of synthetic polymers and their blends with gelatin including those with a semipermeable inner layer were developed. The comparative study of the grafts in vitro and in vivo was carried out. The resistance of VG to displacement, suture retention, layers snagging and compatibility with native artery walls were studied. Also assessed was the time of hemostasis when implanting the grafts consisting of various mixes of polymers, as well as their biocompatibility at different stages of observation. Results. VG produced by electrospinning and containing a semipermeable inner layer possess satisfactory mechanical properties, such as suture retention, resistance to displacement, stability during long term pulsatile stress, do not snag during implantation and form a tight contact with native artery walls. A histological study demonstrates active remodeling of VG including the growth of inner structure typical of a vessel, medium collagen/elastin layer with smooth muscle cells and synthetic fibers and an outer connective tissue capsule without any signature of inflammation. An immunohistochemical study demonstrates more efficient accumulation of smooth muscle cells in VG produced from polycaprolactone (PCL) as compared to other VG tested. VG produced from the PCL-gelatin blend and containing an inner semipermeable layer, as well as similar VG containing polylactic-co-glycolic acid (PLGA) in the inner semipermeable layer tended to produce an endothelial inner layer faster as compared to VG from PCL. However, VG with PLGA acid had a tendency to loose endothelial cells, possibly due to PLGA degradation. VG produced from PCL-gelatin blend and containing the inner semipermeable layer demonstrate limited accumulation of smooth muscle cells and progressive settlement with endothelial cells. Conclusion. A comparative study of different VG produced by electrospinning enables to select variants of polymeric composition and structure of the implant that provide the best bio- and hemocompatibility. VG produced by electrospinning from PCL-gelatin blend and supplied with a semipermeable layer can be recommended for subsequent clinical approbation.Keywords:
Biocompatibility
Electrospinning
Gelatin
Capsule
PLGA
Abstract The biocompatibility and biodegradation rate of component materials are critical when designing a drug-delivery device. The degradation products and rate of degradation may play important roles in determining the local cellular response to the implanted material. In this study, we investigated the biocompatibility and relative biodegradation rates of PLA, PGA and two poly(lactic-co-glycolic acid) (PLGA) polymers of 50 : 50 mol ratio, thin-film component materials of a drug-delivery microchip developed in our laboratory. The in vivo biocompatibility and both in vivo and in vitro degradation of these materials were characterized using several techniques. Total leukocyte concentration measurements showed normal acute and chronic inflammatory responses to the PGA and low-molecular-weight PLGA that resolved by 21 days, while the normal inflammatory responses to the PLA and high-molecular-weight PLGA were resolved but at slower rates up to 21 days. These results were paralleled by thickness measurements of fibrous capsules surrounding the implants, which showed greater maturation of the capsules for the more rapidly degrading materials after 21 days, but less mature capsules of sustained thicknesses for the PLA and high-molecular-weight PLGA up to 49 days. Gel-permeation chromatography of residual polymer samples confirmed classification of the materials as rapidly or slowly degrading. These materials showed thinner fibrous capsules than have been reported for other materials by our laboratory and have suitable biocompatibility and biodegradation rates for an implantable drug-delivery device. Keywords: BIODEGRADATIONBIOCOMPATIBILITYPOLY(GLYCOLIC ACID)POLY(LACTIC ACID)GEL-PERMEATIONCHROMATOGRAPHY
Biocompatibility
PLGA
Glycolic acid
Gel permeation chromatography
Degradation
Biodegradable polymer
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This review considers the main properties of fish gelatin that determine its use in food technologies. A comparative analysis of the amino acid composition of gelatin from cold-water and warm-water fish species, in comparison with gelatin from mammals, which is traditionally used in the food industry, is presented. Fish gelatin is characterized by a reduced content of proline and hydroxyproline which are responsible for the formation of collagen-like triple helices. For this reason, fish gelatin gels are less durable and have lower gelation and melting temperatures than mammalian gelatin. These properties impose significant restrictions on the use of fish gelatin in the technology of gelled food as an alternative to porcine and bovine gelatin. This problem can be solved by modifying the functional characteristics of fish gelatin by adding natural ionic polysaccharides, which, under certain conditions, are capable of forming polyelectrolyte complexes with gelatin, creating additional nodes in the spatial network of the gel.
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Hydroxyproline
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The purpose of this review article is to examine the method of making gelatin, the characteristics of gelatin from the results of research that has been carried out in Indonesia and the benefits of fish gelatin. Based on a review of various articles and other literature, it can be concluded that fish bone gelatin can be extracted by the acid method. The production of fishbone gelatin consists of 4 stages, the preparation of raw materials includes removal of non-collagen components from raw materials, conversion of collagen to gelatin, purification of gelatin by filtering and finally drying and powdering. Fishbone gelatin can be applied to both the food and non-food industries.
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Fish bone
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OBJECTIVE To inspect the biodegradation and biocompatibility of the interferon-α PLGA microspheres.METHODS The degradation of PLGA microspheres in buffer solution in vitro was examined by optical microscope;Wistar rats were employed in this study.The biodegradation and biocompatibility in vivo were evaluated by the pathology slice.RESULTS In vitro the degradation percent of PLGA microspheres was over 80% in 6 weeks;and in vivo PLGA microspheres may be completely degraded in 6 weeks.Slight inflammatory reaction was observed at the part of injection,but pathologic influence was not seen.CONCLUSION The PLGA microspheres have good biodegradation and biocompatibility.
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PLGA
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Gelatin is a product of hydrolysis of collagen protein from animals that are partially processed. Gelatin used in food and non food industries. Gelatin is produced when many import of raw skins and bones of pigs and cows. Goat skins potential as a raw material substitution that still doubt its halal. Process production of gelatin determine the properties of gelatin. The objectives of this research were to determine amino acid profile, group of functional and molecular weight distribution of gelatin made from goat skins which was produced through a process of acid. The skin of male Bligon goat, 1.5 to 2.5 year old was used as raw materials. Process production of gelatin was using acid type acetic acid (CH 3 COOH 0.5 M) (v/v) as curing material. The experimental design applied in this study and commercial gelatin was used as control. The results showed that gelatin produced from goat skin through the process of acid had properties identical with commercial gelatin. It can be concluded that the gelatin has the potential substitute product of commercial gelatin. Keywords : collagen, gelatin, goat skin, curing, acid process
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Amino Acid Analysis
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Abstract In this study, the biocompatibility of a calcium phosphate (CaP) cement incorporating poly ( D,L ‐lactic‐ co ‐glycolic acid) (PLGA) microparticles was evaluated in a subcutaneous implantation model in rats. Short‐term biocompatibility was assessed using pure CaP discs and CaP discs incorporating PLGA microparticles (20% w/w) with and without preincubation in water. Long‐term biocompatibility was assessed using CaP discs incorporating varying amounts (5, 10, or 20% w/w) and diameter sizes (small, 0–50 μm; medium, 51–100 μm, or large, 101–200 μm) of PLGA microparticles. The short‐term biocompatibility results showed a mild tissue response for all implant formulations, irrespective of disc preincubation, during the early implantation periods up to 12 days. Quantitative histological evaluation revealed that the different implant formulations induced the formation of similar fibrous tissue capsules and interfaces. The results concerning long‐term biocompatibility showed that all implants were surrounded by a thin connective tissue capsule (<10 layers of fibroblasts). Additionally, no significant differences in capsule and interface scores were observed between the different implant formulations. The implants containing 20% PLGA with medium‐ and large‐sized microparticles showed fibrous tissue ingrowth throughout the implants, indicating PLGA degradation and interconnectivity of the pores. The results demonstrate that CaP/PLGA composites evoke a minimal inflammatory response. The implants containing 20% PLGA with medium‐ and large‐sized microparticles showed fibrous tissue ingrowth after 12‐ and 24‐weeks indicating PLGA degradation and interconnectivity of the pores. Therefore, CaP/PLGA composites can be regarded as biocompatible biomaterials with potential for bone tissue engineering and advantageous possibilities of the microparticles regarding material porosity. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Biocompatibility
PLGA
Interconnectivity
Microparticle
Capsule
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Physical properties of shark gelatin were examined during gel formation and postgelation in comparison with pig gelatin. Samples with various concentrations and pH values were evaluated by breaking strength, dynamic viscoelasticity, and dynamic light scattering. Sol−gel and gel−sol transition temperatures for shark gelatin were remarkably lower than those for pig gelatin. Shark gelatin gel shows a narrower pH range to form a stable gel compared with pig gelatin. Melting enthalpy of shark gelatin gel was greater than that of pig gelatin gel, and G' of shark gelatin gel changed more extensively with rising temperature in comparison with pig gelatin gel. It is concluded that shark gelatin has different characteristics from pig gelatin not only for gel characteristics but also for the solution property. Keywords: Gelatin; rheology; viscoelasticity; shark; gel
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ゼラチン被覆酸化デシプシ (DAS-gelatin) の尿素処理能を改善するために, DAS-gelatin 粒子表層部に残存しているアルデヒド基にウレアーゼを固定化する試みを行った. DAS-gelatinは腎不全患者の尿素除去剤としての有効性は報告されているが, その吸着速度は遅く, 飽和に達するのに1日を必要とする. DASは尿素よりもアンモニアを速く結合する. DASにウレアーゼを固定化しても酵素活性を示さないが, DAS-gelatin-ureaseは酵素活性を有し, 尿素をアンモニアに加水分解し, このアンモニアはDASによって短時間に処理できる. DAS-gelatin-ureaseの尿素処理量はDAS-gelatinの約2倍である. in vitroでは吸着能が劣るにもかかわらず, 経口投与されたDAS-gelatinは, 腸内で大腸菌の産生するウレアーゼによって加水分解されたアンモニアを吸収するために, DAS-gelatinは臨床において経口投与剤として有効に働くと考えられる. DAS-gelatin-ureaseはpH1.2で失活するところから, 経ロ投与を前提とする場合, DAS-gelatinにあえてウレアーゼを固定化する必要はない. DAS-gelatinは生理活性蛋白質の固定化担体としての利用も考えられる.
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The combined modification (phthalation followed esterification) of gelatin and the effect of esterification on the isoelectric point of phthalated gelatin were studied. The experimental results showed.1. The isoeleetric point of the parent alkali-processed gelatin is 4.57. 2. After the carboxy groups of gelatin were esterified with ethanol, the isoeleetric point of esterified gelatin may be raised up to 5.78 even to 9.60 depending on the degree of esterification. 3. The isoeleetric point of esterified and then phthalated gelatin (PEA gelatin) was 0.48 pH unit higher than that of phthalated gelatin (PA gelatin). 4. The coagulating property of PA and PEA gelatin differs greatly.
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