Acceleration of wound contraction and healing with a photocrosslinkable chitosan hydrogel

Construction of chitosan/carboxylated polyvinyl alcohol/poly(N-isopropylacrylamide) composite antibacterial hydrogel for rapid wound healing

In the realm of skin injury management, the expedited closure of wounds, prevention of scar formation, and enhancement of the healing process are of critical significance. The creation of economical dressings that effectively facilitate swift wound sealing in the initial phase of skin trauma while curbing scar development represents a promising avenue for clinical utility. Within the context of this investigation, we synthesized a novel hydrogel composed of chitosan (CS), carboxylated poly(vinyl alcohol) (PVA-COOH) via a Schiff base reaction between carboxylated PVA and chitosan, yielding networks abundant in amide bonds. Following this, a chitosan/carboxylated PVA/poly(N-isopropylacrylamide) hydrogel (CNP) was engineered by incorporating poly-N-isopropylacrylamide chains for interpenetration at ambient temperature. Our findings indicate that the CNP hydrogel exhibits favorable degradability and swelling characteristics. Moreover, it possesses favorable antimicrobial efficacy and biocompatibility. In a murine full-thickness skin injury model, the hydrogel was found to expedite wound healing by augmenting granulation tissue formation, mitigating wound inflammation, and promoting angiogenesis.

Bio-functionalized hydrogel patches of chitosan for the functional recovery of infarcted myocardial tissue

The aim of this work was to assess the potential benefits of the enrichment of a chitosan hydrogel patch with secretome and its epicardial implantation in a murine model of chronic ischemia, focusing on the potential to restore the functional capacity of the heart. Thus, a hydrogel with a final polymer concentration of 3 % was prepared from chitosan with an acetylation degree of 24 % and then bio-functionalized with a secretome produced by mesenchymal stromal cells. The identification of proteins in the secretomes showed the presence of several proteins known to have beneficial effects on cardiac muscle repair. Then chitosan hydrogels were immersed in secretome. The protein incorporation in the hydrogel and their release over time were studied, demonstrating the ability of the gel to retain and then deliver proteins (around 40 % was released in the first 6 h, and then a plateau was reached). Moreover, mechanical analysis exhibited that the patches remained suturable after enrichment. Finally, bio-functionalized hydrogel patches were sutured onto the surface of the infarcted myocardium in rat. Thirty days after, the presence of enriched hydrogels induced a reversion of cardiac function which seems to come mainly from an improvement of left ventricle systolic performance and contractility.

The application of pH-responsive hyaluronic acid-based essential oils hydrogels with enhanced anti-biofilm and wound healing

pH could play vital role in the wound healing process due to the bacterial metabolites, which is one essential aspect of desirable wound dressings lies in being pH-responsive. This work has prepared a degradable hyaluronic acid hydrogel dressing with wound pH response-ability. The aldehyde-modified hyaluronic acid (AHA) was obtained, followed by complex mixture formation of eugenol and oregano antibacterial essential oil in the AHA-CMCS hydrogel through the Schiff base reaction with carboxymethyl chitosan (CMCS). This hydrogel composite presents pH-responsiveness, its disintegration mass in acidic environment (pH = 5.5) is 4 times that of neutral (pH = 7.2), in which the eugenol release rate increases from 37.6 % to 82.1 %. In vitro antibacterial and in vivo wound healing investigations verified that hydrogels loaded with essential oils have additional 5 times biofilm removal efficiency, and significantly accelerate wound healing. Given its excellent anti-biofilm and target-release properties, the broad application of this hydrogel in bacteria-associated wound management is anticipated.

Chitosan-Aloe Vera Composition Loaded with Zinc Oxide Nanoparticles for Wound Healing: In Vitro and In Vivo Evaluations

Global concerns due to the negative impacts of untreatable wounds, as well as the growing population of these patients, emphasize the critical need for advancements in the wound healing materials and techniques. Nanotechnology offers encouraging avenues for improving wound healing process. In this context, nanoparticles (NPs) and certain natural materials, including chitosan (CS) and aloe vera (AV), have demonstrated the potential to promote healing effects. The objective of this investigation is to assess the effect of novel fabricated nanocomposite gel containing CS, AV, and zinc oxide NPs (ZnO NPs) on the wound healing process. The ZnO NPs were synthesized and characterized by X-ray diffraction and electron microscopy. Then, CS/AV gel with different ratios was prepared and loaded with ZnO NPs. The obtained formulations were characterized in vitro based on an antimicrobial study, and the best formulations were used for the animal study to assess their wound healing effects in 21 days. The ZnO NPs were produced with an average 33 nm particle size and exhibited rod shape morphology. Prepared gels were homogenous with good spreadability, and CS/AV/ZnO NPs formulations showed higher antimicrobial effects against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The wound healing findings showed significant wound area reduction in the CS/AV/ZnO NPs group compared to negative control at day 21. Histopathological assessment revealed the advantageous impact of this formulation across various stages of the wound healing process, including collagen deposition (CS/AV/ZnO NPs (2 : 1), 76.6 ± 3.3 compared to negative control, 46.2 ± 3.7) and epitheliogenesis (CS/AV/ZnO NPs (2 : 1), 3 ± 0.9 compared to negative control, 0.8 ± 0.8). CS/AV gel-loaded ZnO NPs showed significant effectiveness in wound healing and would be suggested as a promising formulation in the wound healing process. Further assessments are warranted to ensure the robustness of our findings.

Efficacy of Chlorhexidine after Oral Surgery Procedures on Wound Healing: Systematic Review and Meta-Analysis

Our objective was to evaluate qualitatively and quantitatively, through a systematic review and meta-analysis, available evidence on the efficacy of chlorhexidine (CHX) when applied after oral surgery on wound healing and related clinical parameters. MEDLINE/PubMed, Embase, CENTRAL, Web of Science, and Scopus were searched for studies published before January 2023. The quality of the methodology used in primary-level studies was assessed using the RoB2 tool; meta-analyses were performed jointly with heterogeneity and small-study effect analyses. Thirty-three studies and 4766 cases were included. The results point out that the application of CHX was significantly more effective, compared to controls where CHX was not employed, providing better wound healing after oral surgery (RR = 0.66, 95% CI = 0.55-0.80, p < 0.001). Stratified meta-analyses confirmed the higher efficacy of 0.20% CHX gel vs. other vehicles and concentrations (p < 0.001, respectively). Likewise, the addition of chitosan to CHX significantly increased the efficacy of surgical wound healing (p < 0.001). The use of CHX has also been significantly beneficial in the prevention of alveolar osteitis after any type of dental extraction (RR = 0.46, 95% CI = 0.39-0.53, p < 0.001) and has also been effective when applied as a gel for a reduction in pain after the surgical extraction of third molars (MD = -0.97, 95% CI = -1.26 to -0.68, p < 0.001). In conclusion, this systematic review and meta-analysis demonstrate on the basis of evidence that the application of CHX exerts a beneficial effect on wound healing after oral surgical procedures, significantly decreasing the patient's risk of developing surgical complications and/or poor wound healing. This benefit was greater when CHX was used at 0.20% in gel form with the addition of chitosan.

Vascular Endothelial Growth Factor Supplementation Enhance Skin Antioxidant Capacity in Hyperglycemic Rats

The fundamental reasons for delayed wound healing in diabetic animals include inadequate production of growth factors or their increased devastation. Vascular Growth Factor (VEGF) has a biological role in the healing process of mucosal and skin wounds, especially in the process of new vessel formation. We planned to examine the oxidant-antioxidant events that occur during healing with topical VEGF application in diabetic rats. Experiments were performed 36 adults female Wistar albino rat diabetes induced by streptozotocin. The incisional wounds were made on the dorsal region in the rats. Rats were separated to 3 groups: the untreated (negative control) group (n=12), the chitosan group (n=12), the chitosan + VEGF group (n=12). The treatments were continued for 3 and 7 days, excluding the control and negative control groups. Then, the animals were sacrificed on the 3rd and 7th days of wound healing. Antioxidant and oxidant parameters in skin tissue were measured using biochemical methods. Topical VEGF application was decreased the NOx levels on the 3rd day compared to other groups. Moreover, it increased wound tissue GSH and AA levels, subsequently contributing to the enhance tissue antioxidant capacity. In conclusion, VEGF application increases the antioxidant capacity of the tissue and simultaneously reduces the oxidative stress and thus gives a positive acceleration to the wound healing process.

Role of Chitosan Hydrogels in Clinical Dentistry

Biopolymers are organic polymers that can be treated into intricate designs with porous characteristics that mimic essential biologic components. Due to their superior biosafety, biodegradability, biocompatibility, etc., they have been utilized immensely in biomedical engineering, regeneration, and drug delivery. To obtain the greatest number of results, a literature search was undertaken in scientific search engines utilizing keywords. Chitosan is used in a variety of medical sectors, with the goal of emphasizing its applications and benefits in the clinical dental industry. Chitosan can be dissolved in liquid form and combined with other substances to create a variety of products, including fibers, hydrogels, membranes, microspheres, resins, sponges, pastes, tablets, and micro granules. Chitosan has been studied in a variety of dental applications. Chitosan is used in the prevention of caries and wear, in pulpotomy to accelerate osteogenesis in guided tissue regeneration due to its hemostatic property, and primarily to benefit from its antimicrobial activity by adding it to materials, such as glass ionomer cement, calcium hydroxide, and adhesive systems. With its antibacterial activity and biocompatibility, chitosan is leading the pack as a promising ingredient in the production of dental materials. The current review provides an update on the background, fundamentals, and wide range of uses of chitosan and its gels in dental science.

Chitosan-based hydrogel wound dressing: From mechanism to applications, a review

As promising biomaterials, hydrogels are widely used in the medical engineering field, especially in wound repairing. Compared with traditional wound dressings, such as gauze and bandage, hydrogel could absorb and retain more water without dissolving or losing its three-dimensional structure, thus avoiding secondary injury and promoting wound healing. Chitosan and its derivatives have become hot research topics for hydrogel wound dressing production due to their unique molecular structure and diverse biological activities. In this review, the mechanism of wound healing was introduced systematically. The mechanism of action of chitosan in the first three stages of wound repair (hemostasis, antimicrobial properties and progranulation), the effect of chitosan deacetylation and the molecular weight on its performance are analyzed. Additionally, the recent progress in intelligent and drug-loaded chitosan-based hydrogels and the features and advantages of chitosan were discussed. Finally, the challenges and prospects for the future development of chitosan-based hydrogels were discussed.

Effects of Nitrurized Titanium on Microhardness and Human Dental Pulp Stem Cell Adhesion and Differentiation

To compare the Vickers microhardness, surface roughness, initial adhesion, and osteogenic differentiation on titanium (Ti) and nitrurized titanium (NTi) plates were treated by UV irradiation and chitosan. Each plate was subjected to Vickers hardness with a pressure of 2.9 N for 10 seconds and roughness evaluation by atomic force microscope (AFM) analysis. Three groups of each type of plates were tested: control (C), ultraviolet irradiation (UV), and chitosan (Q). The UV group was exposed to UV-irradiation for 20 min at 253.7 nm (52 μW/cm2). The Q group was coated with 1% chitosan, and the C group had no treatment. The osteoblasts (2 × 106 cells/mL) were inoculated in each group for 60 min and their viability was determined by the MTT bioassay. Osteogenic differentiation was performed over 4 weeks and determined by alizarin red staining. The mean was analyzed with the Shapiro-Wilks, Kruskall-Wallis, and Mann-Whitney U tests of normality (n = 9/gp). The NTi plates hardness (125.1 ± 4.01 HV) was higher (P = 0.026) than the Ti plates (121.3 ± 2.23 HV). The surface topography was: NTi (Ra = 0.098 μm) and Ti (Ra = 0.212 μm). The quantification of cell adhesion was: Ti + Q = 123 ± 4.9% (P < 0.05) < NTi + Q = 107 ± 3.3% < Ti = 100 ± 10.7% < NTi = 72 ± 6.8% < NTi + UV = 71 ± 4.4% < Ti + UV = 69 ± 3.5%, regardless the plates, the presence of chitosan induce a faster osteogenic differentiation. The Ti + Q plates tested the highest cell attachment and osteogenic adhesion suggesting their potential use of chitosan for cell-implant interaction.

Nanofiber Wound Dressing Materials-A Comparative Study of Wound Healing on a Porcine Model

BACKGROUND

Nanofiber wound dressings remain the domain of in vitro studies. The purpose of our study was to verify the benefits of chitosan (CTS) and polylactide (PLA)-based nanofiber wound dressings on a porcine model of a naturally contaminated standardized wound and compare them with the conventional dressings, i.e., gauze and Inadine.

MATERIAL AND METHODS

The study group included 32 pigs randomized into four homogeneous groups according to the wound dressing type. Standardized wounds were created on their backs, and wound dressings were regularly changed. We evaluated difficulty of handling individual dressing materials and macroscopic appearance of the wounds. Wound swabs were taken for bacteriological examination. Blood samples were obtained to determine blood count values and serum levels of acute phase proteins (serum amyloid A, C-reactive protein, and haptoglobin). The crucial point of the study was histological analysis. Microscopic evaluation was focused on the defect depth and tissue reactions, including formation of the fibrin exudate with neutrophil granulocytes, the layer of granulation and cellular connective tissue, and the reepithelialization. Statistical analysis was performed by using SPSS software. The analysis was based on the Kruskal-Wallis H test and Mann-Whitney U test followed by Bonferroni correction. Significance was set at P < .05.

RESULTS

Macroscopic examination did not show any difference in wound healing among the groups. However, evaluation of histological findings demonstrated that PLA-based nanofiber dressing accelerated the proliferative (P = .025) and reepithelialization (P < .001) healing phases, while chitosan-based nanofiber dressing potentiated and accelerated the inflammatory phase (P = .006). No statistically significant changes were observed in the blood count or acute inflammatory phase proteins during the trial. Different dynamics were noted in serum amyloid A values in the group treated with PLA-based nanofiber dressing (P = .006).

CONCLUSION

Based on the microscopic examination, we have documented a positive effect of nanofiber wound dressings on acceleration of individual phases of the healing process. Nanofiber wound dressings have a potential to become in future part of the common wound care practice.

The performance of gelling fibre wound dressings under clinically relevant robotic laboratory tests

The effectiveness of wound dressing performance in exudate management is commonly gauged in simple, non‐realistic laboratory setups, typically, where dressing specimens are submersed in vessels containing aqueous solutions, rather than by means of clinically relevant test configurations. Specifically, two key fluid–structure interaction concepts: sorptivity—the ability of wound dressings to transfer exudate, including viscous fluids, away from the wound bed by capillary action and durability—the capacity of dressings to maintain their structural integrity over time and particularly, at removal events, have not been properly addressed in existing test protocols. The present article reviews our recent published research concerning the development of clinically relevant testing methods for wound dressings, focussing on the clinical relevance of the tests as well as on the standardisation and automation of laboratory measurements of dressing performance. A second objective of this work was to compile the experimental results characterising the performance of gelling fibre dressings, which were acquired using advanced testing methods, to demonstrate differences across products that apparently belong to the same “gelling fibre” family but differ remarkably in materials, structure and composition and, thereby, in performance.

Angiogenic potential and wound healing efficacy of chitosan derived hydrogels at varied concentrations of APTES in chick and mouse models

Chitosan (Cs) based biomaterials seem to be indispensable for neovasculogenesis and angiogenesis that ensure accelerated wound healing. Cs/poly (vinyl alcohol) (PVA) bio-constructs were cross-linked and investigated with varying concentrations of aminopropyltriethoxysilane (APTES). This study comprised of three phases: fabrication of hydrogels, characterization, assessment of angiogenic potential along with toxico-pathological effects, wound healing efficacy in chick and mice, respectively. The hydrogels were characterized by FTIR, SEM and TGA and the swelling response was examined in different solvents. The hydrogels swelling ratio was decreased with increasing amount of APTES, showed the highest swelling at acidic and basic pH while low swelling at neutral pH. Chorioallantoic membranes (CAM) assay was performed to study in-vivo angiogenesis, toxicological, morphological, biochemical and histological analyses in developing chicks. The results showed remarkably improved angiogenesis with little deviations in morphological, histological features and liver enzymes of chick embryos at higher concentrations of APTES. Besides, full thickness wounds were excised on mice dorsolateral skin to assess the wound healing. The rate of wound size reduction was significantly higher after topical application of hydrogels with elevated levels of crosslinker. Hence, the hydrogels showed enhanced angiogenesis, accelerated wound healing with little or no observable in-vivo toxicity.

Prospection of chitosan and its derivatives in wound healing: Proof of patent analysis (2010-2020)

Disruption in the normal anatomy and physiology of the skin often leads to wound formation. Its healing is a pretty complex and dynamic biological process with different phases. While there are many biopolymers (and their derivatives) for wound healing purposes. One of the most popular, promising, progressive and attention-grabbing biopolymers is 'chitosan'. It is a polysaccharide biopolymer that has tremendous potential in augmenting the process of wound healing. Most importantly, the derivatives of chitosan have heavily attracted the scientific community's attention to employing them in various formulations for wound healing applications. The prime focus of the present review is to provide scientific and technological prospection about chitosan and its derivatives for wound healing activity, starting from 2010 to 2020. Besides, the review also focuses about toxicity, different formulations and products of chitosan that are currently under clinical trials for wound healing purposes are described. Through this review, we present evidence that abundantly confirms that there is a growing interest in the domain of wound healing using novel, inventive, useful and patent protected chitosan derivatives. We speculate the possibility of more patent protected chitosan derivatives in the future for wound healing applications.

Tissue Adhesives: From Research to Clinical Translation

Sutures, staples, clips and skin closure strips are used as the gold standard to close wounds after an injury. In spite of being the present standard of care, the utilization of these conventional methods is precarious amid complicated and sensitive surgeries such as vascular anastomosis, ocular surgeries, nerve repair, or due to the high-risk components included. Tissue adhesives function as an interface to connect the surfaces of wound edges and prevent them from separation. They are fluid or semi-fluid mixtures that can be easily used to seal any wound of any morphology - uniform or irregular. As such, they provide alternatives to new and novel platforms for wound closure methods. In this review, we offer a background on the improvement of distinctive tissue adhesives focusing on the chemistry of some of these products that have been a commercial success from the clinical application perspective. This review is aimed to provide a guide toward innovation of tissue bioadhesive materials and their associated biomedical applications.

Wound healing Activities of the bioactive compounds from Micrococcus sp. OUS9 isolated from marine water

Marine species are increasingly important as a source of specific biological active metabolites. Marine species comprise almost half of global biodiversity. Oceans and sea are thus the biggest source of positive natural compounds that could be utilized in the pharmaceutical industry as functional constituents. In the present study was to find out the wound healing property of the bioactive compounds from Micrococcus sp. OUS9 isolated from marine source. The in vivo wound healing activity was studied using excision wound model. The KLUF 10 and KLUF13 ointment was prepared and used to determine wound healing activity in albino rats. Topical application of the ointment enhanced the contraction of wound in contrast with rat control group. KLUF13 had shown strong healing ability in wounds and had a positive influence on the various phases of wound repair.

Bioshell Calcium Oxide (BiSCaO) Ointment for the Disinfection and Healing of Pseudomonas aeruginosa-Infected Wounds in Hairless Rats

Bioshell calcium oxide (BiSCaO) possesses deodorizing properties and broad microbicidal activity. This study aimed to investigate the application of BiSCaO ointment for the prevention and treatment of infection in chronic wounds in healing-impaired patients, without delaying wound healing. The bactericidal activities of 0.04, 0.2, 1, and 5 wt% BiSCaO ointment, 3 wt% povidone iodine ointment, and control (ointment only) were compared to evaluate the in vivo disinfection and healing of Pseudomonas aeruginosa-infected wounds in hairless rats. Treatment of the infected wounds with 0.2 wt% BiSCaO ointment daily for 3 days significantly enhanced wound healing and reduced the in vivo bacterial counts compared with povidone iodine ointment and control (no wound cleaning). Although 5 wt% BiSCaO ointment provided the lowest bacterial counts during 3 days' treatment, it delayed wound healing. Histological examinations showed significantly advanced granulation tissue and capillary formation in wounds treated with 0.2 wt% BiSCaO ointment for 3 days compared to wounds treated with the other ointments. This study suggested that using 0.2 wt% BiSCaO ointment as a disinfectant for infected wounds and limiting disinfection to 3 days may be sufficient to avoid the negative effects of BiSCaO on wound repair.

Chitosan based hydrogels and their use in medicine

Chitosan is a natural biopolymer, polysaccharide, a product of chitin deacetylation. Chitosan is a non-toxic, biocompatible and biodegradable polymer with high biological activity and stability in the environment. In addition, chitosan is obtained from natural renewable resources and is an inexpensive substance. Due to all these properties, chitosan is widely used in practical medicine, for example, in the form of hydrogel dosage forms in combination with natural and synthetic polymers. This review is focused on polymer hydrogel materials based on chitosan. Special attention is paid to the preparation and use of wound dressings for the treatment of wounds of various etiologies. The use of hydrogel wound dressings based on this polysaccharide allows to create a protective shell on the surface of various wounds, to prolong delivery of antibacterial agents, peptides and other active substances, which significantly increases the effectiveness of therapy. Bactericidal and sorption properties of chitosan-based hydrogels established in experimental and clinical studies are discussed.

Oral Administration of Chitosan Attenuates Bleomycin-induced Pulmonary Fibrosis in Rats

BACKGROUND/AIM

Idiopathic pulmonary fibrosis (PF) is a fatal disorder of unknown aetiology with limited treatment options. Chitosan has antibacterial, antifungal, antioxidant, antitumour, and anti-inflammatory effects. This study aimed to investigate the effects of chitosan administration on bleomycin (BLM)-induced PF in rats.

MATERIALS AND METHODS

A PF rat model was established by endotracheal instillation of 5 mg/kg BLM; then, chitosan was administered in drinking water for 3 weeks. Histology, cell counts, and cytokine responses in the bronchoalveolar lavage fluid (BALF) and weight measurements (body and lung) were analyzed to assess its therapeutic effects.

RESULTS

Chitosan administration tended to reduce transforming growth factor (TGF)-β1 and interferon (IFN)-γ levels in BALF, and histopathological examination confirmed that chitosan attenuated the degree of inflammation and fibrosis in the lung.

CONCLUSION

This study revealed that oral chitosan exhibits potential antifibrotic effects, as measured by decreased proinflammatory cytokine levels and histological evaluation, in a BLM-induced PF rat model.

Preparation and in vivo evaluation of a topical hydrogel system incorporating highly skin-permeable growth factors, quercetin, and oxygen carriers for enhanced diabetic wound-healing therapy

PURPOSE

We created and evaluated an enhanced topical delivery system featuring a combination of highly skin-permeable growth factors (GFs), quercetin (QCN), and oxygen; these synergistically accelerated re-epithelialization and granulation tissue formation of/in diabetic wounds by increasing the levels of GFs and antioxidants, and the oxygen partial pressure, at the wound site.

METHODS

To enhance the therapeutic effects of exogenous administration of GFs for the treatment of diabetic wounds, we prepared highly skin-permeable GF complexes comprised of epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I), platelet-derived growth factor-A (PDGF-A), and basic fibroblast growth factor (bFGF), genetically attached, via the N-termini, to a low-molecular-weight protamine (LMWP) to form LMWP-EGF, LMWP-IGF-I, LMWP-PDGF-A, and LMWP-bFGF, respectively. Furthermore, quercetin (QCN)- and oxygen-carrying 1-bromoperfluorooctane (PFOB)-loaded nanoemulsions (QCN-NE and OXY-PFOB-NE) were developed to improve the topical delivery of QCN and oxygen, respectively. After confirming the enhanced penetration of LMWP-GFs, QCN-NE, and oxygen delivered from OXY-PFOB-NE across human epidermis, we evaluated the effects of combining LMWP-GFs, QCN-NE, and OXY-PFOB-NE on proliferation of keratinocytes and fibroblasts, and the chronic wound closure rate of a diabetic mouse model.

RESULTS

The optimal ratios of LMWP-EGF, LMWP-IGF-I, LMWP-PDGF-A, LMWP-bFGF, QCN-NE, and OXY-PFOB-NE were 1, 1, 0.02, 0.02, 0.2, and 60, respectively. Moreover, a Carbopol hydrogel containing LMWP-GFs, QCN-NE, and OXY-PFOB-NE (LMWP-GFs/QCN-NE/OXY-PFOB-NE-GEL) significantly improved scratch-wound recovery of keratinocytes and fibroblasts in vitro compared to that afforded by hydrogels containing each component alone. LMWP-GFs/QCN-NE/OXY-PFOB-NE-GEL significantly accelerated wound-healing in a diabetic mouse model, decreasing wound size by 54 and 35% compared to the vehicle and LMWP-GFs, respectively.

CONCLUSION

LMWP-GFs/QCN-NE/OXY-PFOB-NE-GEL synergistically accelerated the healing of chronic wounds, exerting both rapid and prolonged effects.

Polyelectrolyte Complexes of Natural Polymers and Their Biomedical Applications

Polyelectrolyte complexes (PECs), composed of natural and biodegradable polymers, (such as positively charged chitosan or protamine and negatively charged glycosaminoglycans (GAGs)) have attracted attention as hydrogels, films, hydrocolloids, and nano-/micro-particles (N/MPs) for biomedical applications. This is due to their biocompatibility and biological activities. These PECs have been used as drug and cell delivery carriers, hemostats, wound dressings, tissue adhesives, and scaffolds for tissue engineering. In addition to their comprehensive review, this review describes our original studies and provides an overview of the characteristics of chitosan-based hydrogel, including photo-cross-linkable chitosan hydrogel and hydrocolloidal PECs, as well as molecular-weight heparin (LH)/positively charged protamine (P) N/MPs. These are generated by electrostatic interactions between negatively charged LH and positively charged P together with their potential biomedical applications.

Biocompatibility of synthetic ultraviolet radiation cross-linked polymers - Subcutaneous implantation study

Photo-cross-linked polymers have attracted a lot of attention in the biomedical field. The main benefits of these materials are related to the fact that they are most of the time viscous liquids or pastes that adapt a custom and fixed shape on demand of the user. Present study deals specifically with the biological response upon subcutaneous implantation of four different materials in rabbits. In the study 20 rabbits were divided into four groups (each five rabbits): Groups 1-3 were implanted with tested new obtained by us macromonomers (P1838-DMA; P1838-UR; PDEGA-UR - respectively), while group 4 (control) was implanted with the mesh (PLA) routinely used for surgical treatment of a hernia. The new compounds were polarized earlier using ultraviolet radiation to obtain cross-linked networks. The polymers in the form of discs were then implanted subcutaneously in dorsal region of rabbits. After 28 days polymers were explanted and examined. Microscopic observation evaluated: thickness of the connective tissue capsule around the discs, cells of inflammatory response, disc surface erosion, spectroscopic analysis. The examined materials cause no chronic inflammation, abscesses or tissue necrosis, and the biological response is similar to observed in control group. Therefore, new synthetic materials could be considered as biocompatible and safe. Materials undergo slow degradation of ester bonds and surface erosion and degradation products could be eliminated probably by phagocytosis. On the basis on the afore mentioned knowledge, we formulated hypothesis, that the new polymers are well tolerated by the adjacent tissues. The aim of the following study was to examine reaction of the tissue on new types of prepolymerized material implanted subcutaneously. The obtained results suggest, that the new UV cross-linked polymers do not affect negatively on the connective tissue that is in the contact with the implants. Furthermore, the used materials are in the liquid form, thus they could be easily performed in in minimally invasive laparoscopic treatment of abdominal hernias. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1889-1897, 2019.

Study on the morphological and biocompatible properties of chitosan grafted silk fibre reinforced PVA films for tissue engineering applications

The current study delineates the preparation of novel chitosan grafted silk fibre reinforced Poly (vinyl alcohol) (PVA) composite films with desirable properties. Although silk fibroin has been extensively used for various biomedical applications, its properties could be further re-tailored for its suitability in the field of regenerative medicine. Chitosan was successfully grafted over silk, via acylation with succinic anhydride and thereby the fibres were incised and used for the preparation of the films. The grafted silk fibre reinforced PVA films were subjected to FTIR studies, microscopic analysis by atomic force microscopy (AFM) and optical microscopy techniques, X-ray diffraction (XRD) analysis and further evaluated for in vitro biocompatibility studies. The composite films demonstrated improved surface roughness with increasing concentration of the fibre and its dispersion in the polymer matrix was observed. Furthermore, in vitro biocompatibility and cellular behaviour such as adhesion and proliferation of mouse fibroblasts as well as astrocyte cells was studied and the results showed improved proliferative activity, when compared to the pristine PVA films. These results were further supported by the results confirmed by MTT assay demonstrating the films to be non-toxic. The efficiency and feasibility of the films to be used for tissue engineering, was further evaluated by haemocompatibility studies using human erythrocytes, thus making them a potential material to be used for biomedical applications.

Topical simvastatin gel as a novel therapeutic modality for palatal donor site wound healing following free gingival graft procedure

OBJECTIVE

Autogenous soft-tissue grafting is a commonly used procedure nowadays in dentistry. However, the prolonged healing time needed for the donor site leads to increase the patient's pain and discomfort. Statin has been observed to be beneficial in reducing bacterial burden, improving epithelization and wound healing. The aim of this study was to evaluate intra-oral topical application of simvastatin/chitosan gel (10 mg/mL) over the palatal donor site following free gingival graft (FGG) procedure.

MATERIAL AND METHODS

Subjects indicated for FGG procedure were divided into four groups. Group I: Simvastatin suspension (S), group II: simvastatin/chitosan gel (SC), group III: chitosan gel (C), group IV: petroleum gel (P). Treatment was applied three times/day for the following 7 days. Wound healing was evaluated at day 3, 7 and 14 post-surgery. A visual analogue scale (VAS) was used to measure the experienced discomfort at 1, 3, 5, 7 and 14 days.

RESULTS

Statistical significant reduction in wound-healing scores was observed after 3 and 7 days for group II compared to other groups (p  = .015). A significant reduction was also observed in VAS score for group II compared to other groups at day 1, 3, 5 and 7.

CONCLUSION

Topical application of S/C gel could be used as a novel therapeutic modality that improved healing and reduced pain in the palatal donor site following FGG procedure.

Preparation and in vivo evaluation of a novel gel-based wound dressing using arginine–alginate surface-modified chitosan nanofibers

The development of an effective wound dressing with the ability to induce skin wound healing is a great challenge in medicine. Nanofibers are highly attractive for wound dressing preparation due to their properties such as hemostasis induction, good absorption of wound exudates, and facilitation of cell growth. Chitosan nanofibers have attracted great attention for application in wound dressings due to their accelerating effects on wound healing. In this study, arginine surface-modified chitosan nanofibers were successfully prepared by attachment of arginine molecules on the surface of chitosan nanofibers using sodium alginate through electrostatic interaction. The effect of pH on the amount of attached arginine was evaluated at three different pH values; 5, 6, and 7. Fourier-transform infrared spectroscopy and zeta potential of chitosan nanofibers before and after surface modification suggested the occurrence of the attachment of arginine to chitosan nanofibers. Scanning electron microscope images showed the nanofibrous structure of arginine surface-modified chitosan nanofibers with an average diameter ranging from 100 nm to 150 nm. The release of arginine from arginine surface-modified chitosan nanofibers gel showed a sustained release manner. The suitable viscosity and spreadability of arginine surface-modified chitosan nanofibers gel verified its easy application at the wound site. Arginine surface-modified chitosan nanofibers gel significantly improved the wound healing process including wound closure when tested in vivo using rat model. Additionally, histological examination and immunohistochemical studies showed the significant enhancement of the re-epithelialization, collagen deposition, and angiogenesis in the skin of the animal group treated with arginine surface-modified chitosan nanofibers gel compared with the other control groups. These results suggested that arginine surface-modified chitosan nanofibers gel could be introduced as an effective wound dressing.

Chitin and chitosan: biopolymers for wound management

Chitin and chitosan are biopolymers with excellent bioactive properties, such as biodegradability, non-toxicity, biocompatibility, haemostatic activity and antimicrobial activity. A wide variety of biomedical applications for chitin and chitin derivatives have been reported, including wound-healing applications. They are reported to promote rapid dermal regeneration and accelerate wound healing. A number of dressing materials based on chitin and chitosan have been developed for the treatment of wounds. Chitin and chitosan with beneficial intrinsic properties and high potential for wound healing are attractive biopolymers for wound management. This review presents an overview of properties, biomedical applications and the role of these biopolymers in wound care.

Optimization and Evaluation of Gastroretentive Ranitidine HCl Microspheres by Using Factorial Design with Improved Bioavailability and Mucosal Integrity in Ulcer Model

The purpose of our investigation was to develop and optimize the drug entrapment efficiency and bioadhesion properties of mucoadhesive chitosan microspheres containing ranitidine HCl prepared by an ionotropic gelation method as a gastroretentive delivery system; thus, we improved their protective and therapeutic gastric effects in an ulcer model. A 3 × 2² full factorial design was adopted to study the effect of three different factors, i.e., the type of polymer at three levels (chitosan, chitosan/hydroxypropylmethylcellulose, and chitosan/methylcellulose), the type of solvent at two levels (acetic acid and lactic acid), and the type of chitosan at two levels (low molecular weight (LMW) and high molecular weight (HMW)). The studied responses were particle size, swelling index, drug entrapment efficiency, bioadhesion (as determined by wash-off and rinsing tests), and T _80% of drug release. Studies of the in vivo mucoadhesion and in vivo protective and healing effects of the optimized formula against gastric ulcers were carried out using albino rats (with induced gastric ulceration) and were compared to the effects of free ranitidine powder. A pharmacokinetic study in rabbits showed a significant, 2.1-fold increase in theAUC_0-24of the ranitidine microspheres compared to free ranitidine after oral administration. The optimized formula showed higher drug entrapment efficiency and mucoadhesion properties and had more protective and healing effects on induced gastric ulcers in rats than ranitidine powder. In conclusion, the prolonged gastrointestinal residence time and the stability of the mucoadhesive microspheres of ranitidine as well as the synergistic healing effect of chitosan could contribute to increasing the potential of its anti-gastric ulcer activity.

A novel in situ silver/hyaluronan bio-nanocomposite fabrics for wound and chronic ulcer dressing: In vitro and in vivo evaluations

In-situ formed hyaluronan/silver (HA/Ag) nanoparticles (NPs) were used to prepare composite fibers/fabrics for the first time. Different concentrations of silver nitrate (1, 2mg/100ml) were added at ambient temperature to sodium hyaluronate solution (40mg/ml), then the pH was increased to 8 by adding sodium hydroxide. The in-situ formed HA/Ag-NPs were used to prepare fibers/nonwoven fabrics by wet-dry-spinning technique (WDST). UV/vis spectroscopy, SEM, TEM, DLS, XPS, XRD and TGA were employed to characterize the structure and composition of the nanocomposite, surface morphology of fiber/fabrics, particle size of Ag-NPs, chemical interactions of Ag⁰ and HA functional groups, crystallinity and thermal stability of the wound dressing, respectively. The resultant HA/Ag-NPs1 and HA/Ag-NPs2 composite showed uniformly dispersed throughout HA fiber/fabrics (SEM), an excellent distribution of Ag-NPs with 25±2, nm size (TEM, DLS) and acceptable mechanical properties. The XRD analysis showed that the in-situ preparation of Ag-NPs increased the crystallinity of the resultant fabrics as well as the thermal stability. The antibacterial performance of medical HA/Ag-NPs fabrics was evaluated against gram negative bacteria E. coli K12, exhibiting significant bactericidal activity. The fibers did not show any cytotoxicity against human keratinocyte cell line (HaCaT). In-vivo animal tests indicated that the prepared wound dressing has strong healing efficacy (non-diabetics/diabetics rat model) compared to the plain HA fabrics and greatly accelerated the healing process. Based on our results, the new HA/Ag-NPs-2mg nonwoven wound dressing fabrics can be used in treating wounds and chronic ulcers as well as cell carrier in different biological research and tissue engineering.

Chitosan as a starting material for wound healing applications

Chitosan and its derivatives have attracted great attention due to their properties beneficial for application to wound healing. The main focus of the present review is to summarize studies involving chitosan and its derivatives, especially N,N,N-trimethyl-chitosan (TMC), N,O-carboxymethyl-chitosan (CMC) and O-carboxymethyl-N,N,N-trimethyl-chitosan (CMTMC), used to accelerate wound healing. Moreover, formulation strategies for chitosan and its derivatives, as well as their in vitro, in vivo and clinical applications in wound healing are described.

Chitosan Hydrogels for the Regeneration of Infarcted Myocardium: Preparation, Physicochemical Characterization, and Biological Evaluation

The formation of chitosan hydrogels without any external cross-linking agent was successfully achieved by inducing the gelation of a viscous chitosan solution with aqueous NaOH or gaseous NH3. The hydrogels produced from high molecular weight (Mw ≈ 640 000 g mol(-1)) and extensively deacetylated chitosan (DA ≈ 2.8%) at polymer concentrations above ∼2.0% exhibited improved mechanical properties due to the increase of the chain entanglements and intermolecular junctions. The results also show that the physicochemical and mechanical properties of chitosan hydrogels can be controlled by varying their polymer concentration and by controlling the gelation conditions, that is, by using different gelation routes. The biological evaluation of such hydrogels for regeneration of infarcted myocardium revealed that chitosan hydrogels prepared from 1.5% polymer solutions were perfectly incorporated onto the epicardial surface of the heart and presented partial degradation accompanied by mononuclear cell infiltration.

Chitosan hydrogels significantly limit left ventricular infarction and remodeling and preserve myocardial contractility

BACKGROUND

Left ventricular myocardial infarctions (MIs) consist of a central area of myocardial necrosis that is surrounded by areas of myocardial injury and ischemia. We hypothesized that chitosan hydrogels, when injected around the perimeter of MIs in rats, could decrease left ventricle (LV) wall stress by the Law of LaPlace, and therefore myocardial oxygen requirements, and prevent the ischemic and injured myocardium from becoming necrotic. In this manner, chitosan gels could limit LV infraction size and LV remodeling. Chitosan hydrogels are liquid at 25°C but gel at 37°C.

METHODS

Seventy Sprague-Dawley rats with ligation of the left coronary artery were treated with either Dulbecco's Modified Eagle Medium (DMEM) or chitosan hydrogel in DMEM, which was injected around the infarct perimeter. Echocardiograms were obtained before MI and at 2, 4, 8, 12, and 16 wk after MI. Hearts from randomly selected rats were harvested at baseline and at the time of echocardiography for determinations of LV infarct size, remodeling, and histopathology.

RESULTS

Infarct sizes as a percentage of the total ventricular myocardium in the DMEM group averaged 17% versus 14% in the chitosan group at 4 wk (P < 0.05), 18% versus 14% at 8 wk (P < 0.01), 19% versus 14% at 12 wk (P < 0.001), and 20% versus 14% at 16 wk (P < 0.001). Injection of chitosan into the infarctions produced LV wall thicknesses in the MI border zones that averaged 0.66 cm at 4 wk, which were greater than the LV wall thicknesses in the border zones of rats treated with DMEM, which averaged 0.33 cm (P < 0.01). Arteriole densities in the MI border zones were 160/mm(2) in the chitosan group but only 92/mm(2) in the DMEM rats (P < 0.01). The left ventricular end-diastolic diameters (LVEDs) in the rats averaged 0.73 cm before MI. After MI, LVED increased in the DMEM rats to 0.84 cm at 2 wk, then 0.89 cm at 4 wk, 0.89 cm at 8 wk, 0.89 m at 12 wk, and 0.87 cm at 16 wk. In contrast, LVED in the chitosan rats were on average 19% smaller in comparison with the DMEM rats (P < 0.05) and did not significantly change in comparison with their baseline LVEDs. Left ventricular ejection fraction (LVEF) in the rats averaged 83% before infarctions. In the infarction + DMEM group, the LVEFs significantly decreased after MI and averaged 59.7% at 2 wk, 52.5% at 4 wk, 46.1% at 8 wk, 52.4% at 12 wk, and 53.6% at 16 wk (P < 0.05). In the infarction + chitosan-treated rats, the LVEFs were greater and averaged 67.8% at 2 wk (P < 0.02), 68.9% (P < 0.02) at 4 wk, 69% (P < 0.003) at 8 wk, 65.2% at 12 wk (P < 0.05), and 67% at 16 wk (P < 0.05).

CONCLUSIONS

Chitosan gel can increase LV myocardial wall thickness, decrease infarct size and LV remodeling, and preserve LV contractility.

Effects of different forms of chitosan on intercellular junctions of mouse fibroblasts in vitro

Chitosan is a linear polysaccharide that has many biomedical applications. We compared the effects of chitosan, in both solution and membranous form, on intercellular adhesion of Swiss 3T3 mouse fibroblasts. Cells were grown as spheroidal cell cultures. Some control cell spheroids were cultured without chitosan and two experimental groups were cultured with chitosan. Chitosan in solution was used for one experimental group and chitosan in membranous form was used for the other. For each group, intercellular adhesion was investigated on days 5 and 10 of culture. Transmission electron microscopy revealed well-defined cellular projections that were more prominent in cells exposed to either membranous or solution forms of chitosan than to the chitosan-free control. Immunocytochemical staining of ICAM-1 and e-cadherin was used to determine the development of intercellular junctions. Compared to the weakly stained control, strong reactions were observed in both chitosan exposed groups at both 5 and 10 days. Cells were treated with 5-bromo-2-deoxyuridine (BrdU) and incubated with anti-BrdU primary antibody to assess proliferation. Both the solution and membranous forms of chitosan increased proliferation at both 5 and 10 days. Cellular viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT). The MTT assay indicated high cell viability; maximum viability was obtained with the solution form of chitosan at day 5. Chitosan exposure increased the number of intercellular junctions and showed a significant proliferative effect on 3T3 mouse fibroblasts.

Chitosan aerosol inhalation alleviates lipopolysaccharide- induced pulmonary fibrosis in rats

PURPOSE

Pulmonary fibrosis (PF) is an insidiously progressive scarring disorder of the alveoli and is associated with high mortality. Currently, therapies available are associated with restricted efficacy and side effects. This study aimed to investigate the effect of chitosan aerosol inhalation on lipopolysaccharide (LPS)-induced pulmonary remodeling and fibrosis in rats.

METHODS

A rat model of PF was established by intratracheal injection of LPS (5 mg/kg). Chitosan was nebulized to rats from day 4 to 28 after LPS injection. We analyzed the effect of chitosan on LPS-induced pulmonary remodeling and fibrosis by hematoxylin-eosin staining (HE), Masson staining, and the determination of the hydroxyproline content. The expression intensities of matrix metalloproteinase-3 (MMP-3) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were analyzed by western blots.

RESULTS

Histological assessments showed that chitosan aerosol inhalation attenuated the fibrotic changes in LPS-induced PF in rats. Compared with the LPS group, the fibrosis parameters were significantly improved in the LPS + chitosan group (LCh group), although not as good as those of the control group. The expressions of MMP-3 and TIMP-1 in the LCh group were markedly less than that of the LPS group on the 28th day.

CONCLUSIONS

Our findings show that chitosan aerosol inhalation inhibits the expression of MMP-3 and TIMP-1, and ameliorates LPS-induced pulmonary remodeling and fibrosis in rats.

Chitin, chitosan, and its derivatives for wound healing: old and new materials

Chitin (β-(1-4)-poly-N-acetyl-d-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. It is often converted to its more deacetylated derivative, chitosan. Previously, many reports have indicated the accelerating effects of chitin, chitosan, and its derivatives on wound healing. More recently, chemically modified or nano-fibrous chitin and chitosan have been developed, and their effects on wound healing have been evaluated. In this review, the studies on the wound-healing effects of chitin, chitosan, and its derivatives are summarized. Moreover, the development of adhesive-based chitin and chitosan are also described. The evidence indicates that chitin, chitosan, and its derivatives are beneficial for the wound healing process. More recently, it is also indicate that some nano-based materials from chitin and chitosan are beneficial than chitin and chitosan for wound healing. Clinical applications of nano-based chitin and chitosan are also expected.

Differences between Solution and Membrane Forms of Chitosan on the In Vitro Activity of Fibroblasts

BACKGROUND

Chitosan, a linear polysaccharide, has been recently used in biomedical applications. In vitro studies have demonstrated its effect on cellular growth and its stimulatory action on cellular layer formation.

AIMS

The present study aims to compare the proliferative effects of chitosan in two forms, membranous and solution forms, on Swiss 3T3 mouse embryonic fibroblasts.

STUDY DESIGN

In vitro study.

METHODS

Three experimental groups were formed: cells were cultured in a normal medium without chitosan (Control Group); cells were cultured either in a medium containing 2.0% chitosan in membranous form (Membrane Group) or chitosan solution at a concentration of 2.0% (Solution Group). Two different methods were used in the experiments: cells cultured on the medium containing chitosan in solution or membranous forms (method 1); and chitosan solution or membranous forms were added into the medium containing previously cultured cells (method 2).

RESULTS

Scanning electron microscopic investigations of the experimental groups revealed cells with well-defined cellular projections, intact cellular membranes and tight intercellular junctions. They were especially prominent in the membrane group of method 1 and in the membrane and solution groups of method 2. Mouse monoclonal anti-collagen 1 primary antibody was used to indicate collagen synthesis. Prominent collagen synthesis was detected in the membrane groups on the 10(th) day of culture for both methods. Bromodeoxyuridine (BrdU) and MTT assays were performed in order to assess cellular proliferation and viability, respectively. BrdU labelling tests indicated a higher proliferation index in the membrane group of method 1 on the 5(th) and 10(th) days. For the second method, the membranous form on the 10(th) day and solution form on the 5(th) day were the most effective groups in terms of cellular proliferation. MTT results reflected a high cellular viability in method 1 on the 5(th) day of treatment with the membranous form, whereas cellular viability was highest in the solution form of method 2 on the 5(th) day.

CONCLUSION

The membranous form of chitosan induced a significant proliferative effect and increased the ratio of cell-to-cell junctions of Swiss 3T3 mouse embryonic fibroblasts. Conveniently, the solution form also resulted in enhanced cell proliferation and viability compared to the control group. As the solution form is easy to prepare and apply to cells compared to the membrane form, the application of Chitosan directly to media appears to be a convenient alternative for tissue engineering approaches.

Wound healing efficacy of a chitosan-based film-forming gel containing tyrothricin in various rat wound models

The objective of this study was to evaluate the healing effects of a chitosan-based, film-forming gel containing tyrothricin (TYR) in various rat wound models, including burn, abrasion, incision, and excision models. After solidification, the chitosan film layer successfully covered and protected a variety of wounds. Wound size was measured at predetermined timepoints after wound induction, and the effects of the film-forming gel were compared with negative (no treatment) and positive control groups (commercially available sodium fusidate ointment and TYR gel). In burn, abrasion and excision wound models, the film-forming gel enabled significantly better healing from 1 to 6 days after wound induction, compared with the negative control. Importantly, the film-forming gel also enabled significantly better healing compared with the positive control treatments. In the incision wound model, the breaking strength of wound strips from the group treated with the film-forming gel was significantly increased compared with both the negative and positive control groups. Histological studies revealed advanced granulation tissue formation and epithelialization in wounds treated with the film-forming gel. We hypothesize that the superior healing effects of the film-forming gel are due to wound occlusion, conferred by the chitosan film. Our data suggest that this film-forming gel may be useful in treating various wounds, including burn, abrasion, incision and excision wounds.

In vitro degradation and in vivo biocompatibility of chitosan–poly(butylene succinate) fiber mesh scaffolds

In tissue engineering, the evaluation of the host response to the biomaterial implantation must be assessed to determine the extent of the inflammatory reaction. We studied the degradation of poly(butylene succinate) and chitosan in vitro using lipase and lysozyme enzymes, respectively. The subcutaneous implantation of the scaffolds was performed to assess tissue response. The type of inflammatory cells present in the surrounding tissue, as well as within the scaffold, was determined histologically and by immunohistochemistry. In the presence of lipase or lysozyme, the water uptake of the scaffolds increased. Based on the weight loss data and scanning electron microscopy analysis, the lysozyme combined with lipase had a notable effect on the in vitro degradation of the scaffolds. The in vivo implantation showed a normal inflammatory response, with presence of neutrophils, in a first stage, and macrophages, lymphocytes, and giant cells in a later stage. Vascularization in the surrounding tissue and within the implant increased with time. Moreover, the collagen deposition increased with time inside the implant. In vivo, the scaffolds maintained the structural integrity. The degradation in vitro was faster and greater compared to that observed in vivo within the same time periods.