فایل ورد کامل مهندسی بافت غضروف با استفاده از سلول های غضروفی گوش انسان جاسازی شده در مواد مختلف هیدروژل

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توجه : در صورت مشاهده بهم ریختگی احتمالی در متون زیر ،دلیل ان کپی کردن این مطالب از داخل فایل می باشد و در فایل اصلی فایل ورد کامل مهندسی بافت غضروف با استفاده از سلول های غضروفی گوش انسان جاسازی شده در مواد مختلف هیدروژل،به هیچ وجه بهم ریختگی وجود ندارد

تعداد صفحات این فایل: ۲۵ صفحه

در ژاپن وزرات بهداشت، کار و رفاه، در سال ۲۰۰۰ اعلام کرد که محصولات حیوانی از کشور و یا مناطق با وجود  انسفالوپاتی اسپانجیفرم گاوی برای استفاده به عنوان   تجهیزات و ابزار پزشکی ممنوع است. بر اساس تغییرات موجود در وقوع BSE یا سیاست هر  ملت، عرضه برای  ابزار های پزشکی   برگرفته از گاو ها با پیگرد قانونی همراه است. در رابطه با این موضوع، مواد سنتتیک نیز دارای قابلیت هایی خوبی خواهند بود زیرا قادر به کنترل آلودگی و واکنش ایمنی می باشد. از این روی، انتظارات در خصوص پپتید های سنتتیک به عنوان جایگزین هایی برای مواد برگرفته از ارگانیسم ها در حال افزایش است. افزایش  در توانایی  جامد شدن می تواند موجب بهبود مقاومت سلول ها و ماتریکس ها  شود. در مطالعه موجود، ما به آرامی سوسپانسیون  سلول/ PuraMatrix را  در محیط تعدیل شده  با اسیدیته خنثی برای تشکیل ژل قرار دادیم.  استفاده از دیش های  چاهک دار می تواند به خنثی سازی فوری PuraMatrix و تشکیل سریع ژل بر اساس گزارشات تولید کنندگان کمک کند و این در حالی است که ما  نتوانسته ایم این رویکرد را اتخاذ کنیم زیرا  ما باید  یک روش یکنواخت و یکسان آزمایشی  مشابه با کلاژن آتلوپپتید یا آلژینات داشته باشیم که در آن  دیش های ترانسول استفاده نشده باشند.  توسعه پپتید های سنتتیک  می تواند  مواد هیدروژلی مناسبی را برای ایجاد غضروف های باز زایی شده ایده آل  فراهم کنند.

عنوان انگلیسی:Cartilage tissue engineering using human auricular chondrocytes embedded in different hydrogel materials~~en~~

INTRODUCTION Tissue engineering has been researched and developed to aid in the repair or reconstruction of defective or injured organs. In tissue engineering, the artificial tissues are composed of living cells, often with a suitable scaffold. The scaffold provides the seeded cells with the space for function and supports their activities. Because every scaffold possesses specific properties that fit some kinds of cells or mimic other tissues in mechanical strength, we should choose the optimal scaffold based on the characteristics of the target cells and tissues. Cartilage is one of the expectative targets for tissue engineering, because cartilage differs from other tissues in its limited capacity for self-repair.1 The diffi- culty in the self-repair of cartilage seems to be due to the lack of a sufficient supply of healthy chondrocytes to the defective sites or to the low productivity of matrices in regenerated chondrocytes. Cartilage tissue engineering could overcome such limitations by using ex vivo culture techniques and supportive artificial materials. In principle, chondrocyte activities are maintained when they are placed in the proper 3D environment. During the development and growth of cartilage, the chondrocytes produce abundant matrices, encase themselves within cavities, and are eventually separated from each other.2 In contrast, the chondrocytes deviated from the physiological 3D environment rapidly lose the typical phenotype and protein synthesis, which is termed dedifferentiation.3 In cartilage tissue engineering, the chondrocytes isolated from their original tissues would be conditioned in a 3D environment, mimicking the physiological situation with favorable scaffolds so as to reproduce their functions and enhance protein synthesis. To date, attempts have been made to use two types of scaffolds for cartilage tissue engineering. The first is a solid type of scaffold including a honeycomb, porous body, mesh, sponge, and unwoven fabric.4 The solid-type scaffolds have some advantages in shaping the macroscopic structure of regenerated tissues or in supporting their mechanical strength. However, the use of solid-type scaffolds includes practical conflicts. The smaller the pore sizes are, the more difficult it will be for the cell suspension to infiltrate into the scaffold. In contrast, when the pore sizes of solid scaffolds are increased, the chondrocytes are attached to the walls of huge pores, but they are not placed in a 3D condition. The second is a hydrogel. Various materials derived from animals or plants, for example, collagen type I gel,5 atelopeptides of collagen,6 fibrin glue,7 gelatin,8 agarose,9 or alginate,10,11 are classified as this type. Although the hydrogel lacks mechanical strength in itself, this type of material can be mixed with cells and can surround the seeded cells in all directions. The hydrogel type of scaffold could be used to reconstruct the 3D environment for the chondrocytes in cartilage tissue engineering. Many previous articles reported that those hydrogel materials were more effective in retaining chondrocyte functions or promoting matrix synthesis, when compared with monolayer culture.6,9,12 However, the biological specificities of each hydrogel materials have seldom been compared with each other. Van Susante and coworkers compared the potentials of both collagen type I and alginate gels as carriers for bovine articular chondrocytes, and evaluated the proliferation and proteoglycan synthesis of chondrocytes when the cells were cultured in an encapsulation with each gel in media containing 10% fetus bovine serum. The collagen type I gel had promoted chondrocyte proliferation, but the alginate gel had an advantage in proteoglycan synthesis.13 Because this collagen type I gel had been prepared in extraction with acetic acid,5 it preserved some telopeptides of collagen and antigenicity. At present, atelopeptides of collagen that were treated with protease have been regarded to show even lower immunogenicity than does native collagen that has usually been used as a medical device for treatment of tissue defects or tissue engineering.14 In the present study, we selected some kinds of hydrogel scaffolds that are or will soon be clinically available, and examined proliferation and matrix synthesis of human chondrocytes in the encapsulation with them so as to provide information on the choice of a suitable scaffold for clinical application. We focused on atelopeptides of collagen and alginate, both of which have been used as materials for medical devices, and either of which is a typical hydrogel material derived from animals or plants. Because the atelopeptide collagen spontaneously polymerizes into a stable gel at neutral pH and physiological temperature, and because the alginate undergoes instant ionotrophic gelation in the presence of divalent cations such as Ca2, they are widely used for the 3D culture studies of chondrocytes.6,10 In addition to both materials derived from animals or plants, synthetic peptides were also evaluated as a potential candidate for a clinically-available hydrogel scaffold. The synthetic peptides, PuraMatrix™, have been recently designed to serve as substrates for cell growth, differentiation, and biological functions. PuraMatrix™ is composed of synthetic polypeptides (AcN-(RADA)4-CNH2).15 The motif RAD was incorporated to mimic the known cell adhesion motif RGD that is found in many ECM proteins.16 They assemble to form an in vivo-like 3D extracellular matrix hydrogel around 37°C at pH 7, suggesting characteristics similar to the atelopeptide collagen. This has been used for research on hepatic regeneration or nerve regeneration and has been reported to promote neurite outgrowth and synaptic formation in neural cells, as well as functional differentiation in hepatocyte-like cells.15,17 At present, clinical trials of the PuraMatrix™ for use in the orthopedic field have been planned by the suppliers.

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