We compared the structure and mechanical properties of scaffolds based on pure collagen, pure chitosan, and a mixture of these polymers. The role of the composition and structure of scaffolds in the maintenance of cell functions (proliferation, differentiation, and migration) was demonstrated in two experimental models: homogeneous tissue analogues (scaffold populated by fibroblasts) and complex skin equivalents (fibroblasts and keratinocytes). In contrast to collagen scaffolds, pure chitosan inhibited the growth of fibroblasts that did not form contacts with chitosan fibers, but formed specific cellular conglomerates, spheroids, and lose their ability to synthesize natural extracellular matrix. However, the use of chitosan as an additive stimulated proliferative activity of fibroblasts on collagen, which can be associated with improvement of mechanical properties of the collagen scaffolds. The effectiveness of chitosan as an additional cross-linking agent also manifested in its ability to improve significantly the resistance of collagen scaffolds to fibroblast contraction in comparison with glutaraldehyde treatment. Polymer scaffolds (without cells) accelerated complete healing of skin wounds in vivo irrespective of their composition healing, pure chitosan sponge being most effective. We concluded that the use of chitosan as the scaffold for skin equivalents populated with skin cells is impractical, whereas it can be an effective modifier of polymer scaffolds.
Objectives:The conversion of tissue engineering into a routine clinical tool cannot be achieved without a deep understanding of the interaction between cells and scaffolds during the process of tissue formation in an artificial environment. Here, we have investigated the cultivation conditions and structural features of the biodegradable non-woven material in order to obtain a well-differentiated human airway epithelium. Materials and methods:The bilayered scaffold was fabricated by electrospinning technology. The efficiency of the scaffold has been evaluated using MTT cell proliferation assay, histology, immunofluorescence and electron microscopy. Results:With the use of a copolymer of chitosan-gelatin-poly-l-lactide, a bilayered non-woven scaffold was generated and characterized. The optimal structural parameters of both layers for cell proliferation and differentiation were determined. The basal airway epithelial cells differentiated into ciliary and goblet cells and formed pseudostratified epithelial layer on the surface of the scaffold. In addition, keratinocytes formed a skin equivalent when seeded on the same scaffold. A comparative analysis of growth and differentiation for both types of epithelium was performed. Conclusions:The structural parameters of nanofibres should be selected experimentally depending on polymer composition. The major challenges on the way to obtain the well-differentiated equivalent of respiratory epithelium on non-woven scaffold include the following: the balance between scaffold permeability and thickness, proper combination of synthetic and natural components, and culture conditions sufficient for co-culturing of airway epithelial cells and fibroblasts. For generation of skin equivalent, the lack of diffusion is not so critical as for pseudostratified airway epithelium.
Plasma treatment is one of the most promising tools to control surface properties of materials tailored for biomedical application. Among a variety of processing conditions, such as the nature of the working gas and time of treatment, discharge type is rarely studied, because it is mainly fixed by equipment used. This study aimed to investigate the effect of discharge type (direct vs. alternated current) using air as the working gas on plasma treatment of poly(ethylene terephthalate) films, in terms of their surface chemical structure, morphology and properties using X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy and contact angle measurements. The effect of the observed changes in terms of subsequent chitosan immobilization on plasma-treated films was also evaluated. The ability of native, plasma-treated and chitosan-coated films to support adhesion and growth of mesenchymal stem cells was studied to determine the practicability of this approach for the biomedical application of poly(ethylene terephthalate) films.
Objectives/Hypothesis To develop an experimental model in rabbits for assessment of tracheal epithelium regeneration through application of either natural or artificial polymer scaffolds. Study Design First, we identified the size of full‐thickness mucosal defect, which does not allow self‐healing (a “critical defect”), thus representing an adequate experimental model for regenerative therapy of tracheal epithelium damage. Then, two methods of polymer scaffold fixation at the site of the epithelium defect were compared: suturing and fixation with a stent. This was done through: 1) formation of a full‐thickness anterolateral mucosal defect by tracheal mucosa excision; and 2) fixation of the scaffold at the site of the tracheal epithelium defect using sutures (through a tracheal wall “window”) or a vascular stent (through a small tracheal incision). Results The dimension of a critical anterolateral mucosal defect of the trachea for rabbits was found to be 1.5 cm in length and more than 50% of the tracheal circumference. Fixation of the scaffold with a stent proved to be more efficient due to a uniform distribution of the pressure over the entire surface of the scaffold, whereas the suturing of the scaffold provided unsatisfactory results. In addition, fixation of the scaffold by suturing required formation of a large “window” in the tracheal wall. Thus, using the stent appeared to be technically less complicated and much less traumatic as compared to suturing. Conclusion We present an experimental in vivo animal model of tracheal epithelium injury and recovery. It can be effectively used with certain further modifications as a basis for routine testing of bioengineered constructs. Level of Evidence NA Laryngoscope, 129:E213–E219, 2019
В статье представлен анализ клинических и гистологических признаков 62 морфологически подтвержденных диспластических невусов и двух меланом. Известно, что диспластические невусы, впервые описанные W. Clark в 1978 г., способны трансформироваться в меланому. Процесс трансформации происходит постепенно, по мере развития лентигинозной меланоцитарной дисплазии (ЛМД) от I до III степени. Цель исследования -определить клинические признаки прогрессирующего диспластического невуса (ЛМД II-III степени, выявленная при гистологическом исследовании), подлежащего удалению с целью профилактики перехода невуса в злокачественную опухоль. Материал и методы. С 2009 по 2014 г. в хирургическом отделении «ЗАО Центральная поликлиника Литфонда» путем эксцизионной биопсии удалены 82 пигментных образования с клиническим диагнозом диспластический невус. В 62 случаях диагноз подтвержден, т.е. при гистологическом исследовании установлена лентигинозная меланоцитарная дисплазия, в том числе в 38 случаях -в комбинации с пограничным или смешанным невусом, в двух случаях выявлена меланома. Прогрессирующий диспластический невус (т.е. ЛМД II-III степени) был обнаружен в 20 случаях из 62. Результаты. Сопоставление клинических и гистологических признаков удаленных образований показало, что клинически диспластические невусы с ЛМД II-III степени, т.е. прогрессирующие диспластические невусы, отличаются от невусов с дисплазией I-II степени. Таким образом, по клиническим признакам можно заподозрить прогрессирующий диспластический невус, наличие которого определяет тактику ведения больного с пигментными образованиями. Выводы. Наиболее значимым признаком прогрессирующего диспластического невуса является возникновение пигментного образования на неизмененной коже и рост его у лиц после полового созревания, или изменения существующего невуса в последние несколько месяцев или лет у лиц старше 17 лет. Прогрессирующие диспластические невусы необходимо подвергать иссечению в целях профилактики и ранней диагностики меланомы кожи. Иссечение невуса (эксцизионная биопсия) следует производить под местной анестезией, отступя от видимых границ 0,4-1,0 см, с подкожной клетчаткой. Гистологическое исследование должен производить патоморфолог, имеющий опыт диагностики меланоцитарных образований. При обнаружении меланомы вопрос о реоперации решается в зависимости от толщины опухоли, определяемой при гистологическом исследовании. Ключевые слова: лентигинозная меланоцитарная дисплазия, прогрессирующий диспластический невус, меланома.The paper presents an analysis of the clinical and histologic signs of 62 morphologically dysplastic confirmed nevi and two melanomas. Dysplastic nevi, which were first described by W. Clark in 1978, are known to be able to transform into melanoma. The transformation process occurs gradually, as lentiginous melanocytic dysplasia (LMD) develops from I to III grade. Aim. The aim of the study was to determine the clinical signs of progressive dysplastic nevus (II-III grade LMD detected by a histological examination) that should be removed to prevent t...
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