Study on gelatin-containing artificial skin IV: A comparative study on the effect of antibiotic and EGF on cell proliferation during epidermal healing

Enhanced full-thickness wound healing via Sophora gibbosa extract delivery based on a chitosan/gelatin dressing incorporating microemulsion

There are many synthetic drugs in literature have been utilized in healing of the wounds although the natural product specially antioxidants can offer similar if not better biological activity in that regard. Genus Sophora is well known to contain flavonoids and phenolic compounds which have antioxidant and inflammatory effects. So, the aim of the current study was to develop and evaluate chitosan/gelatin based Sophora gibbosa extract-loaded microemulsion as wound dressing. Sophora gibbosa extract (SGE) contained 16 major compounds which have reasonable antioxidant activity. The developed microemulsion showed that Tween 80 produced significant (p < 0.05) lower particle size than Pluronic F127 at the same SGE concentration whereas high concentration of extract results in large particle size. Thermodynamic stability studies showed that using higher concentration of the extract produced less stable formulations. The selected formulation was impregnated in the dressing base (chitosan/gelatin; 2:1 w/w ratio) which exhibited more water absorption. In vivo evaluation revealed that the dressing displayed superior wound repair compared to the control in terms histological examination and determination of alpha smooth muscle actin (α-SMA) and proliferating cell nuclear antigen (PCNA). Thus, SGE-loaded microemulsion-impregnated gelatin/chitosan could be a potential candidate for the wound healing.

Biomodification of a Class-V Restorative Material by Incorporation of Bioactive Agents

Restoring subgingival class-V cavities successfully, demand special biological properties from a restorative material. This study aimed to assess the effects of incorporating bioactive materials to glass ionomer cement (GIC) on its mechanical and biological properties. Hydroxyapatite, chitosan, chondroitin sulphate, bioglass, gelatine and processed bovine dentin were incorporated into a GIC restorative material. Compressive strength, biaxial flexural strength (BFS), hardness, setting and working time measurements were investigated. Biocompatibility of the new materials was assessed using both monolayer cell cultures of normal oral fibroblasts (NOF) and TR146 keratinocytes, and a 3D-tissue engineered human oral mucosa model (3D-OMM) using presto-blue tissue viability assay and histological examination. Significant reduction in the compressive strength and BFS of gelatine-modified discs was observed, while chondroitin sulphate-modified discs had reduced BFS only (p value > 0.05). For hardness, working and setting times, only bioglass caused significant increase in the working time. NOF viability was significantly increased when exposed to GIC-modified with bovine dentine, bioglass and chitosan. Histological examination showed curling and growth of the epithelial layer toward the disc space, except for the GIC modified with gelatine. This study has highlighted the potential for clinical application of the modified GICs with hydroxyapatite, chitosan, bioglass and bovine dentine in subgingival class-V restorations.

Effect of Topical Application of Black Seed Oil on Imiquimod-Induced Psoriasis-like Lesions in the Thin Skin of Adult Male Albino Rats

Psoriasis is a chronic inflammatory skin disease that affects about 1%-3% of the world's population. Black seed oil, i.e., the oil extracted from black seeds (Nigella sativa seeds), possesses a broad spectrum of pharmacological actions including anti-inflammatory, immunostimulatory, and antioxidant properties. This study aimed to investigate the effect of black seed oil on imiquimod (IMQ) induced psoriasis-like skin lesions. To this end, 30 male albino rats were divided into three groups: group I, control group; group II, psoriasis-induced group receiving daily topical applications of IMQ cream (5%) on the shaved back skin for 10 consecutive days; and group III, black seed oil group receiving a daily topical dose of black seed oil 5 mg/kg body weight for 10 days after induction of psoriasis. Animals of all groups were sacrificed and specimens obtained from the skin of the central part of the back were processed for histological and immunohistochemical staining with proliferating cell nuclear antigen (PCNA). IMQ application led to epidermal inflammation, hyperplasia and alterations in the normal appearance of keratinocytes with degenerative changes observed at both light and electron microscopic levels. Collagenous fibers were abundant in the dermis and PCNA-positive cells were detected in all layers of the epidermis. However, topical use of black seed oil strongly inhibited IMQ-induced psoriasis-like inflammation and alleviated all epidermal and dermal changes observed after IMQ application, allowing us to conclude that black seed oil can be used as an adjuvant topical therapy for treating psoriasis. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 301:166-174, 2018. © 2017 Wiley Periodicals, Inc.

EGF Loaded Chitosan Sponges as Wound Dressing Material

The aim of this study was to prepare and characterize chitosan sponges using epidermal growth factor (EGF) for wound healing. Chitosan sponges were prepared by solvent evaporation (or precipitation) combined with chemical cross-linking techniques. The chitosan polymer was weighed and dissolved in aqueous acetic acid solution (5% v/v) and injected into absolute ethanol containing a cross-linker (ethylene glycol diglycydyl ether). The growth factor (EGF) was loaded into sponges by adding it into the chitosan solution. The EGF loaded chitosan sponges were used in fibroblast cell culture studies to investigate the effects of EGF released on cell proliferation and to determine the effects of the different variables on EGF release; such as, chitosan Mw, cross-linker, the needle injecting the chitosan solution into the precipitation medium, chitosan/EGF ratio and pH of the medium. The swelling of the sponges was higher in the lower molecular weight chitosan, with less cross-linker and using a small diameter injection needle. The swelling increased with decreasing chitosan/EGF ratio and the EGF release rate was increased by increasing the sponge swelling. The cell proliferation (cell growth) increased with increasing swelling ratio.

Drug delivery systems for wound healing

Protein, gene, and small molecule therapies hold great potential for facilitating comprehensive tissue repair and regeneration. However, their clinical value will rely on effective delivery systems which maximize their therapeutic benefit. Significant advances have been made in recent years towards biomaterial delivery systems to satisfy this clinical need. Here we summarize the most outstanding advances in drug delivery technology for cutaneous wound healing.

Tailoring the properties of gelatin films for drug delivery applications: influence of the chemical cross-linking method

Two types of chemically cross-linked gelatin films were prepared and characterized. The first type of films was cross-linked with 1-ethyl-3-(3-dimethyl aminopropyl)carbodiimide hydrochloride (EDC) under heterogeneous conditions and are named Gel-E. In the second type of films, gelatin was previously functionalized with methacrylamide side groups by the reaction with methacrylic anhydride and for that is named Gel-MA. The modified gelatin was subsequently cross-linked by a photoinitiated radical polymerization. These films were characterized relatively to their degree of cross-linking, buffer uptake capacity, resistance to hydrolytic and proteolytic degradation, and mechanical and thermal properties. Results show that the employed cross-linking method, together with the degree cross-linking, dictate the final properties of the films. Gel-E films have significant lower buffer uptake capacities and higher resistance to collagenase digestion when compared to Gel-MA films. Additionally, Gel-E films exhibit higher values of stress at break and lower strains at break. Moreover, the films properties could be modified by varying the extent of the chemical cross-linking, which in turn could be controlled by varying the concentration of EDC, for the first type of films (Gel-E), or by using gelatins with different degrees of functionalization, in the case of the second type of films (Gel-MA).

In vitro and in vivo epidermal growth factor gene therapy for diabetic ulcers with electrospun fibrous meshes

Human epidermal growth factor (hEGF) gene therapy was achieved with an electrospun nanofibrous mesh with matrix metalloproteinase (MMP) responsiveness to control release of plasmid human epidermal growth factor (phEGF) in diabetic ulcers. For MMP responsiveness, linear poly(ethyleneimine) (LPEI) was immobilized on the surface of the nanofiber via an MMP-cleavable linker. phEGF was electrostatically incorporated into LPEI-immobilized nanofibrous meshes with various charge ratios and phEGF incorporation efficiency was increased with increasing charge ratios. The release of both phEGF and LPEI was significantly increased in the presence of MMP-2 due to the enzymatic digestion of the MMP-cleavable linkage between the matrix and LPEI. Human dermal fibroblasts with the released fraction showed a higher expression level of hEGF compared to naked phEGF or phEGF/LPEI complexes. Diabetic wounds treated with phEGF-incorporated nanofibrous meshes showed high hEGF expression level and accelerated wound recovery rates without wound contractions for 14days. Neocollagen and cytokeratin accumulation were significantly increased as well as the expression of the keratinocyte-specific markers at the re-epithelized tissue treated with phEGF nanofibrous meshes, which clearly indicates that EGF gene was transfected to dermal cells and this consequently assisted wound recovery without phenotypic changes of the re-epithelized tissues. Thus, phEGF-incorporated nanofibrous mesh is expected to accelerate the wound-healing process as well as reduce wound contraction during recovery from diabetic ulcers.

Synthetic and bio-artificial tactile sensing: a review

This paper reviews the state of the art of artificial tactile sensing, with a particular focus on bio-hybrid and fully-biological approaches. To this aim, the study of physiology of the human sense of touch and of the coding mechanisms of tactile information is a significant starting point, which is briefly explored in this review. Then, the progress towards the development of an artificial sense of touch are investigated. Artificial tactile sensing is analysed with respect to the possible approaches to fabricate the outer interface layer: synthetic skin versus bio-artificial skin. With particular respect to the synthetic skin approach, a brief overview is provided on various technologies and transduction principles that can be integrated beneath the skin layer. Then, the main focus moves to approaches characterized by the use of bio-artificial skin as an outer layer of the artificial sensory system. Within this design solution for the skin, bio-hybrid and fully-biological tactile sensing systems are thoroughly presented: while significant results have been reported for the development of tissue engineered skins, the development of mechanotransduction units and their integration is a recent trend that is still lagging behind, therefore requiring research efforts and investments. In the last part of the paper, application domains and perspectives of the reviewed tactile sensing technologies are discussed.

Determination and comparison of specifics of nucleus pulposus cells of human intervertebral disc in alginate and chitosan-gelatin scaffolds

INTRODUCTION

Low back pain is a major economical and social problem nowadays. Intervertebral disc herniation and central degeneration of disc are two major reasons of low back pain that occur because of structural impairment of disc. The intervertebral disc contains three parts as follows : Annulus fibrosus, transitional region, and nucleus pulposus, which forms the central nucleus of the disc. The reduction of cell count and extracellular matrix, especially in nucleus pulposus, causes disc degeneration. Different scaffolds (natural and synthetic) have been used for tissue repairing and regeneration of the intervertebral disc in tissue engineering. Most scaffolds have biodegradable and biocompatible characteristics and also prepare a fine condition for proliferation and migration of cells. In this study, proliferation of NP cells of human intervertebral disc compromised in Chitosan-gelatin scaffold with alginate scaffold was studied.

MATERIALS AND METHODS

NP cells derived from nucleus pulposus by collagenase enzymatic hydrolysis. They were derived from patients who undergoing open surgery for discectomy in the Isfahan Alzahra hospital. Chitosan was blended with gelatin and glutaraldehyde was used for cross linking the two polymers. Then, alginate scaffold was prepared. Cellular suspension with 1 × 10(5) transferred to each scaffold and cultured for 21 days. Cell viability and proliferation investigated by trypan blue and (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Scanning electron microscope (SEM) was used to assert the porosity and to survey structure of scaffold.

RESULTS

MTT assay dem1onstrated that cell viability of third day had significant difference in contrast by first day in both scaffolds. Accordingly, there was a significant decreased in cellular viability from day 3 to 21. Results of the cell count showed a punctual elevation cell numbers for alginate scaffold but there was no similar result for chitosan-gelatin scaffold.

CONCLUSION

Alginate scaffold prepared a better condition for proliferation of NP cells in comparison with chitosan-gelatin scaffold. Results of this study suggest that alginate scaffold could be useful in in vivo studies and treatment.

Biocompatibility and biodegradation of cross-linked gelatin/hyaluronic acid sponge in rat subcutaneous tissue

A gelatin/hyaluronic acid (GH) sponge has been fabricated by freeze-drying and cross-linking. The GH sponge was insoluble when cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The morphologies of sponges were investigated using a field emission scanning electron microscope. The porosity of the GH sponge increased with hyaluronic acid content. The GH sponge was biodegradable, as evidenced by implantation in Wistar rat subcutaneous connective tissue. Fibroblasts infiltrated into the sponge matrix, and regenerated collagen in the matrix to a level of 25% by 15 days after surgery. The GH73 sponge induced an acute inflammatory response compared with the GH91 sponge. This inflammatory response could have been stimulated by the presence of hyaluronic acid up to Day 10, as it decreased afterwards. The C-reactive protein of blood samples also indicated the same result. The blood tests and histological results show that GH sponges have good biocompatibility and low antigenicity for tissue engineering scaffolds.

Efficacy of chitin-PAA-GTMAC gel in promoting wound healing: animal study

Acrylic grafted chitin (chitin-PAA) was modified with glycidyltrimethylammonium chloride (GTMAC) with the aim of promoting wound healing. The chitin-PAA-GTMAC gels with different GTMAC contents were compared with the original chitin-PAA gel and Intrasite gel for their efficacy in deep wound healing of Wistar rats. Four full-thickness wounds were made on the dorsal skin of rats and then each was treated with 4 materials; chitin-PAA, chitin-PAA-GTMAC(1:4), chitin-PAA-GTMAC(1:10) and Intrasite gel. During 18 days of treatment, the wounds were visually observed and calculated for wound size using image analysis program. Skin wound tissues of sacrificed rats were processed for routine histological observation and immunohistochemistry of proliferating cell nuclear antigen (PCNA). The wounds covered with the chitin derivatives either with or without GTMAC showed a significant reduction in wound size in day 9 in comparison with day 12 for those covered with Intrasite gel. The faster rate and the better pattern of epidermal development observed in histological study as well as the higher dermal cell proliferation (PCNA expression) also demonstrated the better efficiency in wound healing of the chitin derivatives than Intrasite. The earliest epidermal development of the wounds treated with chitin-PAA-GTMAC (1:4) among the tested materials suggested the most promising of this material for the treatment of full-thickness open wound.

Potential applications of natural origin polymer-based systems in soft tissue regeneration

Despite the many advances in tissue engineering approaches, scientists still face significant challenges in trying to repair and replace soft tissues. Nature-inspired routes involving the creation of polymer-based systems of natural origins constitute an interesting alternative route to produce novel materials. The interest in these materials comes from the possibility of constructing multi-component systems that can be manipulated by composition allowing one to mimic the tissue environment required for the cellular regeneration of soft tissues. For this purpose, factors such as the design, choice, and compatibility of the polymers are considered to be key factors for successful strategies in soft tissue regeneration. More recently, polysaccharide-protein based systems have being increasingly studied and proposed for the treatment of soft tissues. The characteristics, properties, and compatibility of the resulting materials investigated in the last 10 years, as well as commercially available matrices or those currently under investigation are the subject matter of this review.

Preparation of porous collagen/hyaluronic acid hybrid scaffolds for biomimetic functionalization through biochemical binding affinity

This study demonstrated the feasibility of introducing an avidin-biotin system to three-dimensional and highly porous scaffolds for the purpose of designing scaffolds that have binding affinity with bioactive molecules for various biomimetic modifications. Porous hybrid scaffolds composed of collagen and hyaluronic acid (HA) were prepared by a novel overrun process. The overrun-processed scaffolds showed a uniform dual-pore structure because of the injection of gas bubbles and ice recrystallization during the fabrication process and had a higher porosity than scaffolds prepared by a conventional freeze-drying method. The mechanical strength and biodegradation kinetics were controlled by the method of preparation and the composition of collagen/HA. Collagen/HA scaffolds did not show any significant adverse effects on cell viability even after 10 days of incubation. The fibroblasts cultured in the overrun-processed scaffolds were widely distributed and had proliferated on the surfaces of the macropores in the scaffolds, whereas the cells that were seeded in the freeze-dried scaffolds had attached mainly on the dense surface of the scaffolds. As the collagen content in the scaffolds increased, the cellular ingrowth into the inner pores of the scaffolds decreased because of the high affinity between the collagen and the cells. Measurements obtained via confocal microscopy revealed that the porous collagen/HA scaffolds could be functionalized with the biotin by incorporating avidin. Therefore, the present biotinylation approach may allow the incorporation of various bioactive molecules (DNA, growth factors, drug, peptide, etc) into the three-dimensional porous scaffolds.

Tissue-engineered oral mucosa: a review of the scientific literature

Tissue-engineered oral mucosal equivalents have been developed for clinical applications and also for in vitro studies of biocompatibility, mucosal irritation, disease, and other basic oral biology phenomena. This paper reviews different tissue-engineering strategies used for the production of human oral mucosal equivalents, their relative advantages and drawbacks, and their applications. Techniques used for skin tissue engineering that may possibly be used for in vitro reconstruction of human oral mucosa are also discussed.

Novel porous gelatin scaffolds by overrun/particle leaching process for tissue engineering applications

Porous gelatin scaffolds were prepared using a modified overrun process, which is a novel method for preparing a porous matrix by injecting air and mixing polymer solution at low temperature. The pores in the scaffolds formed by the overrun process exhibited a dual-pore structure due to the injection of air bubbles and ice recrystallization. However, the morphology of the overrun-processed gelatin scaffolds had closed pore structures. The closed pore structure was reformed into a uniformly distributed and interconnected open structure by the combination of the overrun process and a particle-leaching technique (NaCl and sucrose). The mechanical strength and biodegradation rate of gelatin scaffolds were controlled by the matrix porosity and concentration of gelatin solution. Despite higher porosity, overrun processed gelatin scaffolds showed similar mechanical strength to freeze-dried scaffolds. After 1 week of in vitro culturing, the fibroblasts in overrun-processed scaffolds were widely distributed on the surface of the scaffold pores, whereas cells seeded in freeze-dried scaffolds were mainly placed on the top and bottom of the scaffolds. Therefore, the overrun process combined with a particle-leaching technique can be applied to fabricate porous scaffolds with a desirable cellular structure for tissue engineering applications.

Acceleration of wound healing by gelatin film dressings with epidermal growth factor

We examined in vivo efficiency of a gelatin film sheet with epidermal growth factor (EGF) for a novel therapeutic device for cutaneous wound repair. NIH3T3 fibroblasts and PAM212 keratinocytes proliferated when the cells were incubated with the homogenate of EGF containing gelatin sheets, indicating that the gelatin sheet retained biologic activity of EGF in the process of sheet formation. To evaluate therapeutic effects, the EGF containing gelatin sheets or control sheets were applied onto partial-thickness skin wounds made on dorsa of hairless dogs. Wound closure in wounds treated with EGF containing gelatin sheets was accelerated when compared to that of wounds treated with control sheets, exhibiting earlier reepithelialization of the epidermis and highly regulated repair of extracellular matrix in the dermis. Therefore, we concluded that the gelatin film is a useful material to keep EGF stable and the EGF containing sheet has the ability to become an efficient therapeutic agent for superficial or deep partial-thickness wounds in the skin.

Study of gelatin-containing artificial skin V: fabrication of gelatin scaffolds using a salt-leaching method

Porous gelatin scaffolds were prepared using a salt-leaching method and these were compared to scaffolds fabricated using a freeze-drying method. The salt-leached gelatin scaffolds were easily formed into desired shapes with a uniformly distributed and interconnected pore structure with an average pore size of around 350 microm. The mechanical strength and the biodegradation rate of the scaffolds increased with the porosity, and were easily modulated by the addition of salt. After 1 week of in vitro culturing, the fibroblasts in salt-leached scaffolds were mainly attached on the surface of the pores in the scaffold, whereas cells seeded on freeze-dried scaffolds were widely distributed and aggregated on the top and the bottom of the scaffold. After 14 d of culturing, the fibroblasts showed a good affinity to, and proliferation on, the gelatin scaffolds without showing any signs of biodegradation. An in vivo study of cultured artificial dermal substitutes showed that an artificial dermis containing the fibroblasts enhanced the re-epithelialization of a full-thickness skin defect when compared to an acellular scaffold after 1 week.

Denatured collagen as support for a FGF-2 delivery system: physicochemical characterizations and in vitro release kinetics and bioactivity

Collagen-based materials have scaffold properties to support bioactive molecules such as growth factor (GF). Gelatin, a denatured collagen, may have also some potential to interact with GF. An alternative process to denature collagen using trifluoroacetic acid (TFA) was investigated. Physicochemical characterization (XPS, DSC, isoelectric point, water uptake) of TFA-denatured collagen was comparable to regular gelatin, except a significant hydrophilicity and a pH sensitivity. FGF-2 was mixed with either regular gelatin or TFA-denatured collagen, then incorporated to a collagen sponge. Autoradiography revealed a relatively homogenous distribution of radiolabeled FGF-2 within the sponge. In vitro release kinetic of radiolabeled FGF-2 was investigated as well as the bioactivity of FGF-2 towards endothelial cell growth. The mixture was also sorbed to hydrogels made of ethylene vinyl acetate co-polymer and poly(2-hydroxyethyl methacrylate), and to cell culture insert membranes as control. Release of FGF-2 from collagen was progressive in the presence of TFA-denatured collagen, and cell growth was stimulated (significant peak at 8 and 10 days) by TFA-denatured collagen and FGF-2 eluted particularly from collagen sponges. Whereas control hydrogels, and those with regular gelatin showed a early stimulation of cell growth (1-5 days). Thus, the combination of both FGF-2 and an acid-denatured collagen in collagen sponges allows to sustain in vitro endothelial cell activity.

Bio-artificial skin composed of gelatin and (1-->3), (1-->6)-beta-glucan

Porous scaffolds composed of gelatin and beta-glucan were prepared using the freeze-drying method. The scaffold had an inter-connected pore structure with average pore size of 90-150 microm. Results for the contact angle and cell attachment revealed that a high gelatin content was suitable for cellular attachment and distribution in two- or three-dimensional fibroblast cultures, because the gelatin had acidic residues, and arginine-glycine-aspartic acid groups. To prepare a stratified wound dressing to mimic the normal human skin, fibroblasts and keratinocyte cells were isolated from a child's foreskin, and were co-cultured in gelatin/beta-glucan scaffolds were cross-linked using 1-ethyl-(3-3-dimethylaminopropyl) carbodiimide hydrochloride. An in vivo study showed that after 1 week, the artificial dermis containing the fibroblasts enhanced the re-epithelialization of a full-thickness skin defect rather than the acellular scaffold.

Evaluation of a galactose-carrying gelatin sponge for hepatocytes culture and transplantation

This study proposes a new three-dimensional culture of mouse hepatocytes in a porous galactose-carrying modified gelatin sponge matrix. The modification of gelatin using galactose residues significantly increased the attachment of hepatocytes on the substrate. A modified gelatin sponge with lactobionic acid (MGLA) was prepared to increase the specific interaction between the hepatocytes and the matrix. Hepatocytes cultured in a three-dimensional MGLA sponge released much less lactate dehydrogenase than those cultured on a collagen Type I-coated monolayer. Moreover, the survival rate of hepatocytes cultured on an MGLA sponge was longer than the survival rate of hepatocytes cultured on a collagen Type I-coated monolayer. Hepatic specific metabolic functions, namely, the secretion of serum albumin and the synthesis of urea, were well maintained and promoted by spheroidal hepatocytes formed in the MGLA sponge.