The Experts below are selected from a list of 1950 Experts worldwide ranked by ideXlab platform
Changyou Gao - One of the best experts on this subject based on the ideXlab platform.
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Comparison studies of the in vivo treatment of full-thickness excisional wounds and burns by an artificial bilayer Dermal Equivalent and J-1 acellular Dermal matrix.
Wound repair and regeneration : official publication of the Wound Healing Society [and] the European Tissue Repair Society, 2014Co-Authors: Rui Guo, Jianying Teng, Aibin Huang, Changyou GaoAbstract:The effects upon skin repair were compared between a homemade bilayer Dermal Equivalent (BDE), composed of a collagen/chitosan porous scaffold and a silicone membrane, and J-1 acellular Dermal matrix (ADM), a commercial ADM that is used widely in China to treat various skin defects. Full-thickness excisional and burn wounds were prepared on the backs of pigs and then treated with the BDE and J-1 ADM. Biopsy specimens were harvested on days 7, 14, and 21 after surgery for gross, biochemical, and molecular examinations. In comparison with the burn wounds, the excisional wounds showed accelerated granular tissue formation and superior integration with the Equivalents, regardless of their type. Immunohistochemical, immunofluorescence, real time quantitative polymerase chain reaction and Western blotting analyses showed that the vascularization rates in the excisional wounds group were also significantly faster than those of the burn group for both Dermal Equivalents. There was no significant difference between J-1 ADM and BDE treatment on the formation of newly formed blood vessels for the excisional wounds at days 7, 14, and 21. However, there was a significant difference in the number of nascent blood vessels formed in the burn wounds after treatment with J-1 ADM compared with BDE. The highest numbers of newly formed and mature blood vessels were present in the J-1 ADM-treated excisional wounds after 21 days. Ultrathin skin grafts were further transplanted on to the regenerated dermis for 28 days, resulting in the repair of the full-thickness wounds and production of a structure similar to normal skin.
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rnai functionalized collagen chitosan silicone membrane bilayer Dermal Equivalent for full thickness skin regeneration with inhibited scarring
Biomaterials, 2013Co-Authors: Xing Liu, Jun Liang, Bing Zhang, Jianying Teng, Changyou GaoAbstract:Scar inhibition of Dermal Equivalent is one of the key issues for treatment of full thickness skin defects. To yield a bioactive RNAi functionalized matrix for skin regeneration with inhibited scarring, collagen-chitosan/silicone membrane bilayer Dermal Equivalent (BDE) was combined with trimetylchitosan (TMC)/siRNA complexes which could induce suppression of transforming growth factor-β1 (TGF-β1) pathway. The RNAi-BDE functioned as a reservoir for the incorporated TMC/siRNA complexes, enabling a prolonged siRNA release. The seeded fibroblasts in the RNAi-BDE showed good viability, internalized the TMC/siRNA complexes effectively and suppressed TGF-β1 expression constantly until 14 d. Application of the RNAi-BDE on the full-thickness skin defects of pig backs confirmed the in vivo inhibition of TGF-β1 expression by immunohistochemistry, real-time quantitative PCR and western blotting during 30 d post surgery. The levels of other scar-related factors such as collagen type I, collagen type III and α-smooth muscle actin (α-SMA) were also down-regulated. In combination with the ultra-thin skin graft transplantation for 73 d, the regenerated skin by RNAi-BDE had an extremely similar structure to that of the normal one. Our study reflects the latest paradigm of tissue engineering by incorporating the emerging biomolecule siRNA. The 3-D scaffolding materials for siRNA delivery may have general implications in generation of bioactive matrix as well.
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enhanced angiogenesis of gene activated Dermal Equivalent for treatment of full thickness incisional wounds in a porcine model
Biomaterials, 2010Co-Authors: Rui Guo, Aibin Huang, Changyou GaoAbstract:Abstract Angiogenesis of Dermal Equivalent is one of the key issues for treatment of full thickness skin defects. To develop a gene-activated bilayer Dermal Equivalent (BDE), N,N,N-trimethyl chitosan chloride (TMC), a cationic gene delivery vector, was used to form complexes with the plasmid DNA encoding vascular endothelial growth factor-165 (VEGF-165), which was then incorporated into a collagen–chitosan/silicone membrane scaffold. To evaluate the angiogenesis property in vivo, full thickness skin defects were made on the back of pigs, into which the TMC/pDNA-VEGF complexes loaded BDE and other three control BDEs, i.e. the blank BDE, and the BDEs loaded with pDNA-VEGF and TMC/pDNA-eGFP complexes, respectively, were transplanted. Biopsy specimens were harvested at day 7, 10 and 14 after surgery for histology, immunohistochemistry, immunofluorescence, real-time quantitative PCR (RT-qPCR) and western blotting analyses. The results showed that the TMC/pDNA-VEGF group had the strongest VEGF expression in mRNA and protein levels, resulting in the highest densities of newly-formed and mature vessels. The ultra-thin skin graft was further transplanted onto the dermis regenerated by the TMC/pDNA-VEGF complexes loaded BDE at day 10 and well survived. At 112 days grafting, the healing skin had a similar structure and ∼80% tensile strength of the normal skin.
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a trilayer Dermal Equivalent containing silver nanoparticles with enhanced antibacterial property
Chinese Journal of Polymer Science, 2009Co-Authors: Aibin Huang, Guoyang Wei, Changyou GaoAbstract:A Dermal Equivalent having a trilayered structure was designed by combining a silver nanoparticles incorporated chitosan film with a bilayer collagen-chitosan/silicon membrane Dermal Equivalent (BDE). The silver nanoparticles prepared at different conditions were characterized by UV-Vis and transmission electron microscopy (TEM). The macroscopic sharp and the microstructure of the trilayer Dermal Equivalent (TDE) were also studied. Then, the in vitro antibacterial property of TDE was evaluated by the antibacterial zone test. The effect of the incorporated silver nanoparticles on the resistance of wound infection was further studied by the in vivo animal test. The results prove that the silver nanoparticles incorporated TDE has a better antibacterial property, thus may be potentially applied to a broader field in skin repair such as full thickness defect and burn.
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in vitro and in vivo biological performance of collagen chitosan silicone membrane bilayer Dermal Equivalent
Journal of Materials Science: Materials in Medicine, 2007Co-Authors: Yanchao Shi, Changyou Gao, Yixin Chen, Haiguang Zhao, Chunmao HanAbstract:Skin loss or damage affects severely the life quality of human being and can even cause death in many cases. We report here a bilayer Dermal Equivalent (BDE) composed of collagen-chitosan porous scaffold and silicone membrane, which can effectively induce the regeneration of dermis in an animal model of full thickness skin loss. The in vitro biosecurity test showed that the BDE had no cytotoxicity, and no remarkable sensitization and irritability. In vitro cell culture proved that the BDE had good biocompatibility to support the proliferation of fibroblasts. Animal test was performed on Bama miniature pig skin. Gross view and histological sections found plenty of fibroblasts and extracellular matrix in the regenerative scaffold after transplantation of the BDE for 4 weeks. Immunohistochemistry results proved that the BDE has the ability to support the angiogenesis of the regenerated dermis. All these results indicate that the BDE might be a promising Equivalent in treating Dermal loss.
Chunmao Han - One of the best experts on this subject based on the ideXlab platform.
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in vitro and in vivo biological performance of collagen chitosan silicone membrane bilayer Dermal Equivalent
Journal of Materials Science: Materials in Medicine, 2007Co-Authors: Yanchao Shi, Changyou Gao, Yixin Chen, Haiguang Zhao, Chunmao HanAbstract:Skin loss or damage affects severely the life quality of human being and can even cause death in many cases. We report here a bilayer Dermal Equivalent (BDE) composed of collagen-chitosan porous scaffold and silicone membrane, which can effectively induce the regeneration of dermis in an animal model of full thickness skin loss. The in vitro biosecurity test showed that the BDE had no cytotoxicity, and no remarkable sensitization and irritability. In vitro cell culture proved that the BDE had good biocompatibility to support the proliferation of fibroblasts. Animal test was performed on Bama miniature pig skin. Gross view and histological sections found plenty of fibroblasts and extracellular matrix in the regenerative scaffold after transplantation of the BDE for 4 weeks. Immunohistochemistry results proved that the BDE has the ability to support the angiogenesis of the regenerated dermis. All these results indicate that the BDE might be a promising Equivalent in treating Dermal loss.
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collagen chitosan porous scaffolds with improved biostability for skin tissue engineering
Biomaterials, 2003Co-Authors: Changyou Gao, Xueqing Hu, Jiacong Shen, Zhengwei Mao, Jie Zhou, Chunmao HanAbstract:Porous scaffolds for skin tissue engineering were fabricated by freeze-drying the mixture of collagen and chitosan solutions. Glutaraldehyde (GA) was used to treat the scaffolds to improve their biostability. Confocal laser scanning microscopy observation confirmed the even distribution of these two constituent materials in the scaffold. The GA concentrations have a slight effect on the cross-section morphology and the swelling ratios of the cross-linked scaffolds. The collagenase digestion test proved that the presence of chitosan can obviously improve the biostability of the collagen/chitosan scaffold under the GA treatment, where chitosan might function as a cross-linking bridge. A detail investigation found that a steady increase of the biostability of the collagen/chitosan scaffold was achieved when GA concentration was lower than 0.1%, then was less influenced at a still higher GA concentration up to 0.25%. In vitro culture of human Dermal fibroblasts proved that the GA-treated scaffold could retain the original good cytocompatibility of collagen to effectively accelerate cell infiltration and proliferation. In vivo animal tests further revealed that the scaffold could sufficiently support and accelerate the fibroblasts infiltration from the surrounding tissue. Immunohistochemistry analysis of the scaffold embedded for 28 days indicated that the biodegradation of the 0.25% GA-treated scaffold is a long-term process. All these results suggest that collagen/chitosan scaffold cross-linked by GA is a potential candidate for Dermal Equivalent with enhanced biostability and good biocompatibility.
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thermal dehydration treatment and glutaraldehyde cross linking to increase the biostability of collagen chitosan porous scaffolds used as Dermal Equivalent
Journal of Biomaterials Science-polymer Edition, 2003Co-Authors: Changyou Gao, Zhengwei Mao, Jiacong Shen, Chunmao HanAbstract:A biodegradable scaffold for skin-tissue engineering was designed using collagen and chitosan, which are common materials for biomedical application. The scaffolds containing different amounts of chitosan were prepared by mixing the collagen and chitosan solutions followed by removal of the solvent using a freeze-drying method. The cross-linking treatment of these scaffolds was performed using the dehydrothermal treatment (DHT) method or glutaraldehyde (GA) to increase their biostability. The effect of the chitosan concentration and the cross-linking methods on the morphology of these scaffolds was studied by SEM. The water retention and the biodegradability in vitro of various collagen-chitosan scaffolds were investigated. Finally the biocompatibility of the collagen-chitosan (10 wt% chitosan) scaffold treated with different cross-linking methods was evaluated using a in vivo animal test. A mild inflammatory reaction could be detected in the early stages, and GA treatment can decrease the inflammatory re...
Odile Damour - One of the best experts on this subject based on the ideXlab platform.
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lysyl oxidase like and lysyl oxidase are present in the dermis and epidermis of a skin Equivalent and in human skin and are associated to elastic fibers
Journal of Investigative Dermatology, 2004Co-Authors: Emmanuelle Noblesse, Valerie Cenizo, Charbel Bouez, Agnes Borel, Claudine Gleyzal, Simone Peyrol, Mariepaule Jacob, Pascal Sommer, Odile DamourAbstract:Elastic fiber formation involves the secretion of tropoelastin which is converted to insoluble elastin by cross-linking, initiated by the oxidative deamination of lysine residues by lysyl oxidase. Five lysyl oxidase genes have been discovered. This study deals with the expression of two isoforms, LOX and LOX-like (LOXL), in human foreskin and in a human skin-Equivalent (SE) model that allows the formation of elastic fibers. In this model, keratinocytes are added to a Dermal Equivalent made of fibroblasts grown on a chitosan-cross-linked collagen-GAG matrix. LOX and LOXL were detected by immunohistochemistry in the dermis and the epidermis of both normal skin and in a SE. This expression was confirmed by in situ hybridization on the SE. LOX and LOXL expression patterns were confirmed in human skin. The ultrastructural localization of LOXL was indicative of its association with elastin-positive materials within the SE and human skin, though interaction with collagen could not be discarded. LOX was found on collagen fibers and could be associated with elastin-positive materials in the SE and human skin. LOXL and LOX were detected in keratinocytes where LOX was mainly expressed by differentiating keratinocytes, in contrast to LOXL that can be found in both proliferating and differentiating fibroblasts. These data favor a role for LOXL in elastic fiber formation, together with LOX, and within the epidermis where both enzymes should play a role in post-translational modification of yet unknown substrates.
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lysyl oxidase like and lysyl oxidase are present in the dermis and epidermis of a skin Equivalent and in human skin and are associated to elastic fibers
Journal of Investigative Dermatology, 2004Co-Authors: Emmanuelle Noblesse, Valerie Cenizo, Charbel Bouez, Agnes Borel, Claudine Gleyzal, Simone Peyrol, Mariepaule Jacob, Pascal Sommer, Odile DamourAbstract:Elastic fiber formation involves the secretion of tropoelastin which is converted to insoluble elastin by cross-linking, initiated by the oxidative deamination of lysine residues by lysyl oxidase. Five lysyl oxidase genes have been discovered. This study deals with the expression of two isoforms, LOX and LOX-like (LOXL), in human foreskin and in a human skin-Equivalent (SE) model that allows the formation of elastic fibers. In this model, keratinocytes are added to a Dermal Equivalent made of fibroblasts grown on a chitosan-cross-linked collagen-GAG matrix. LOX and LOXL were detected by immunohistochemistry in the dermis and the epidermis of both normal skin and in a SE. This expression was confirmed by in situ hybridization on the SE. LOX and LOXL expression patterns were confirmed in human skin. The ultrastructural localization of LOXL was indicative of its association with elastin-positive materials within the SE and human skin, though interaction with collagen could not be discarded. LOX was found on collagen fibers and could be associated with elastin-positive materials in the SE and human skin. LOXL and LOX were detected in keratinocytes where LOX was mainly expressed by differentiating keratinocytes, in contrast to LOXL that can be found in both proliferating and differentiating fibroblasts. These data favor a role for LOXL in elastic fiber formation, together with LOX, and within the epidermis where both enzymes should play a role in post-translational modification of yet unknown substrates.
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use of Dermal Equivalent and skin Equivalent models for in vitro cutaneous irritation testing of cosmetic products comparison with in vivo human data
Journal of Toxicology-cutaneous and Ocular Toxicology, 1998Co-Authors: C. Augustin, C. Collombel, Odile DamourAbstract:AbstractThe development of new cosmetic formulations requires precise assessment of their safety and efficacy. Today, legislation imposes increasing measures of safety as well as the limitation of animal use for such testing (European Community directive 93/35/CEE). Subsequently, safety assessment protocols now focus on in vivo human volunteer tests and in vitro methods. In this study, in vivo testing consisted of 48 h patch tests on human volunteers followed by a clinical evaluation of irritation based on a visual scoring system including evaluation of erythema, edema, dryness, and vesicles. For in vitro testing to substantiate the safety of cosmetic products, we propose two three-dimensional models, a Dermal Equivalent (DE) and a skin Equivalent (SE). The DE is composed of a porous collagen-glycosaminoglycans-chitosan Dermal substrate populated by normal human fibroblasts. The SE is completed by a fully differentiated epidermis made by seeding normal human keratinocytes onto the DE.To evaluate the usefu...
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pigmented human skin Equivalent new method of reconstitution by grafting an epithelial sheet onto a non contractile Dermal Equivalent
Pigment Cell Research, 1997Co-Authors: Keiko Nakazawa, C. Collombel, Hisayoshi Nakazawa, Florent Sahuc, Annie Lepavec, Odile DamourAbstract:We have established a new protocol for reconstituting a pigmented human skin Equivalent (PSE) and have evaluated its functional responses to environmental stimulus, UVB. The PSE is reconstituted by grafting an epithelial sheet consisting of keratinocytes and melanocytes onto a porous non-contractile Dermal Equivalent populated with mitotically and metabolically active fibroblasts. i) The PSE has a multilayered, well-differentiated epidermis with cuboidal basal cells and highly organised dermis with newly synthesised extracellular matrix components. ii) Ki67-positive proliferating keratinocytes (18.1 ± 7.4%) were detected on the basal layer of the epidermis. iii) Melanocytes located exclusively within the basal layer were detected by monoclonal antibody against tyrosinase-related protein (TRP-1). iv) After exposure to UVB (100 mJ/cm2 per day) for 7 consecutive days, the intensity of TRP-1 staining was increased in the PSE, showing their functional state, whereas the number of melanocytes was not changed. This non-contractile and functioning new PSE is potentially useful as a model for studying the role of melanocyte-keratinocyte-fibroblast interactions in photoprotection of the skin in more complex cutaneous microenvironment than monolayer culture, and for developing in vitro disease models and therapeutic protocols with genetically altered cells both in epidermis and dermis.
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use of Dermal Equivalent and skin Equivalent models for identifying phototoxic compounds in vitro
Photodermatology Photoimmunology and Photomedicine, 1997Co-Authors: C. Augustin, C. Collombel, Odile DamourAbstract:Phototoxicity inducing in vivo photoirritation, a reversible inflammatory reaction of the skin after chemical contact and UVA radiation exposure, is increasingly observed as a side effect associated with the use of both cosmetics and systemic drugs. In order to systematically screen for the phototoxic potential of new compounds, we propose two three-dimensional models suitable for in vitro testing: a Dermal Equivalent (DE) and a skin Equivalent (SE) model. The DE model includes a collagen-glycosaminoglycans-chitosan porous matrix populated by normal human fibroblasts. The SE model is made by seeding normal human keratinocytes onto the DE, leading to a fully differentiated epidermis. The objectives of this pilot study are: 1) to compare the deleterious effects of UVA radiation on the two models and 2) to evaluate to what extent the in vitro results can predict the in vivo phototoxicity caused by well-known photoirritant compounds, included in the COLIPA validation phototoxicity reference chemical list. Dilutions of thiourea, sulisobenzone, promethazine, chlorpromazine and tetracycline were applied (20 microliters) onto DEs and SEs (n = 6) and incubated for 1 h (or 15 h) at 37 degrees C. Irradiated samples received 3 J/cm2 UVA. The 24 h post-irradiation residual cellular viability was measured using the MTT test on treated and untreated tissues and IL-1 alpha release measurement in collected SE culture media. A concordance in terms of photoirritant/non-photoirritant was obtained between the in vivo data and the in vitro results, suggesting that the DE and the SE models could be integrated, after a complete validation study, into a protocol for in vitro testing of the photoirritant potential of new molecules.
Vivek Mudera - One of the best experts on this subject based on the ideXlab platform.
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a rapid fabricated living Dermal Equivalent for skin tissue engineering an in vivo evaluation in an acute wound model
Tissue Engineering Part A, 2012Co-Authors: M Ananta, R A Brown, Vivek MuderaAbstract:The encapsulation of both cells and a surgical mesh in a polymerizing collagen hydrogel followed by mechanical compression, after polymerization, results in the rapid formation of a living Dermal Equivalent (LDE) with physical properties suitable for in vivo application. It was found in the current study that the LDE supported the attachment, growth, and differentiation of keratinocytes, allowing for the formation of living skin Equivalents (LSEs) with a monolayer epidermis (LSE-M) and a stratified epidermis (LSE-S). The utility of the LDE for the fabrication of living wound dressings was further evaluated by testing the safety and efficacy of the LSE-M and LSE-S in a lapine model of an acute full-thickness skin defect. It was found that the LSE-S significantly stimulated blood vessel formation and accelerated epiDermal wound closure compared with controls. The LSE-M showed similar trends but these were not significant. These findings indicate the clinical usefulness of the LDE in the treatment of acute a...
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a rapid fabricated living Dermal Equivalent for skin tissue engineering an in vivo evaluation in an acute wound model
Tissue Engineering Part A, 2012Co-Authors: M Ananta, R A Brown, Vivek MuderaAbstract:The encapsulation of both cells and a surgical mesh in a polymerizing collagen hydrogel followed by mechanical compression, after polymerization, results in the rapid formation of a living Dermal Equivalent (LDE) with physical properties suitable for in vivo application. It was found in the current study that the LDE supported the attachment, growth, and differentiation of keratinocytes, allowing for the formation of living skin Equivalents (LSEs) with a monolayer epidermis (LSE-M) and a stratified epidermis (LSE-S). The utility of the LDE for the fabrication of living wound dressings was further evaluated by testing the safety and efficacy of the LSE-M and LSE-S in a lapine model of an acute full-thickness skin defect. It was found that the LSE-S significantly stimulated blood vessel formation and accelerated epiDermal wound closure compared with controls. The LSE-M showed similar trends but these were not significant. These findings indicate the clinical usefulness of the LDE in the treatment of acute and possibly chronic wounds, such as venous and diabetic ulcerations. The 1-h fabrication time of the LDE is a significant reduction compared with that of Dermal components of current FDA-approved dressings, such as Dermagraft, Apligraf, and OrCel, which require days to weeks of in vitro culture. It is therefore proposed that the presented method could reduce the high cost associated with the production of living, tissue-engineered dressings.
Jiacong Shen - One of the best experts on this subject based on the ideXlab platform.
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enhanced biological stability of collagen porous scaffolds by using amino acids as novel cross linking bridges
Biomaterials, 2004Co-Authors: Changyou Gao, Zhengwei Mao, Jie Zhou, Jiacong ShenAbstract:Abstract Collagen porous scaffolds have been widely employed as a Dermal Equivalent to induce fibroblasts infiltration and Dermal regeneration. To eliminate the disadvantageous drawback of the fast degradation speed, a cross-linking method was adopted by using a water-soluble carbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDAC) and N -hydroxysuccinimide (NHS) in the presence of amino acids (glycin, glutamic acid or lysine), which function as cross-linking bridge between collagen molecular chains. In vitro assessment of the biological stability of the cross-linked collagen scaffolds found that the collagenase biodegradation degree was greatly decreased when lysine was added, resulting in a more biological stable scaffold. On the other hand, the biodegradation degree was accelerated compared with the purely cross-linked when glutamic acid was added, while less influenced by glycin addition. By comparing the biodegradation degree of the scaffolds added with amino acids and their model compounds, i.e. adipic acid and hexane diamine, the key factor influencing the biological stability was further investigated. The results indicated that the crucial factor is dependent on the ratio of amino groups to carboxyl groups in the cross-linking system. At optimal ratio the lowest biodegradation degree is achieved. Scanning electron microscopy measurements prove that the three-dimensional structure of the scaffolds was largely preserved. Preliminary in vitro culture of fibroblasts in the collagen scaffold cross-linked with EDAC/NHS in the presence of lysine has shown that the original good cytocompatibility of collagen was retained.
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collagen chitosan porous scaffolds with improved biostability for skin tissue engineering
Biomaterials, 2003Co-Authors: Changyou Gao, Xueqing Hu, Jiacong Shen, Zhengwei Mao, Jie Zhou, Chunmao HanAbstract:Porous scaffolds for skin tissue engineering were fabricated by freeze-drying the mixture of collagen and chitosan solutions. Glutaraldehyde (GA) was used to treat the scaffolds to improve their biostability. Confocal laser scanning microscopy observation confirmed the even distribution of these two constituent materials in the scaffold. The GA concentrations have a slight effect on the cross-section morphology and the swelling ratios of the cross-linked scaffolds. The collagenase digestion test proved that the presence of chitosan can obviously improve the biostability of the collagen/chitosan scaffold under the GA treatment, where chitosan might function as a cross-linking bridge. A detail investigation found that a steady increase of the biostability of the collagen/chitosan scaffold was achieved when GA concentration was lower than 0.1%, then was less influenced at a still higher GA concentration up to 0.25%. In vitro culture of human Dermal fibroblasts proved that the GA-treated scaffold could retain the original good cytocompatibility of collagen to effectively accelerate cell infiltration and proliferation. In vivo animal tests further revealed that the scaffold could sufficiently support and accelerate the fibroblasts infiltration from the surrounding tissue. Immunohistochemistry analysis of the scaffold embedded for 28 days indicated that the biodegradation of the 0.25% GA-treated scaffold is a long-term process. All these results suggest that collagen/chitosan scaffold cross-linked by GA is a potential candidate for Dermal Equivalent with enhanced biostability and good biocompatibility.
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fabrication of porous collagen chitosan scaffolds with controlling microstructure for Dermal Equivalent
Polymers for Advanced Technologies, 2003Co-Authors: Changyou Gao, Dengyong Wang, Jiacong ShenAbstract:Two sets of homemade apparatus have been utilized to fabricate collagen/chitosan porous membranes by quenching its acetic solution and subsequently extracting the solvent with ethanol. The influence of chitosan concentration on the surface morphology of the collagen/chitosan membranes was studied using a quenching cold plate (apparatus 1). The pore size was enlarged along with an increase in the chitosan content, accompanied with the emergence of a sheet-like microstructure. Due to the large thermal conductivity of the membrane-forming platform (stainless steel), collagen/chitosan membranes prepared using apparatus 1 at freezing temperature between −60 to −20 °C present similar pore size (2–4 nm) and surface morphology. However, a large difference in pore size is generated using apparatus 2 (membrane preparation in a cold ethanol bath) and using a membrane-forming platform of poor thermal conductivity (polymethylmethacrylate), e.g. ∼10 to 20 μm at freezing temperature of −60 to −40 °C, and 265 μm at −20 °C accompanied with the transformation from fiber- to sheet-dominated morphology. The spongy collagen/chitosan membranes with pore sizes ranging from tens to hundreds of micrometers and porosity higher than 95%, which could be used as Dermal regeneration template, have thus been fabricated. Copyright © 2003 John Wiley & Sons, Ltd.
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thermal dehydration treatment and glutaraldehyde cross linking to increase the biostability of collagen chitosan porous scaffolds used as Dermal Equivalent
Journal of Biomaterials Science-polymer Edition, 2003Co-Authors: Changyou Gao, Zhengwei Mao, Jiacong Shen, Chunmao HanAbstract:A biodegradable scaffold for skin-tissue engineering was designed using collagen and chitosan, which are common materials for biomedical application. The scaffolds containing different amounts of chitosan were prepared by mixing the collagen and chitosan solutions followed by removal of the solvent using a freeze-drying method. The cross-linking treatment of these scaffolds was performed using the dehydrothermal treatment (DHT) method or glutaraldehyde (GA) to increase their biostability. The effect of the chitosan concentration and the cross-linking methods on the morphology of these scaffolds was studied by SEM. The water retention and the biodegradability in vitro of various collagen-chitosan scaffolds were investigated. Finally the biocompatibility of the collagen-chitosan (10 wt% chitosan) scaffold treated with different cross-linking methods was evaluated using a in vivo animal test. A mild inflammatory reaction could be detected in the early stages, and GA treatment can decrease the inflammatory re...