Suture pullout strength andin vitrofibroblast and RAW 264.7 monocyte biocompatibility of genipin crosslinked nanofibrous chitosan mats for guided tissue regeneration

Chitosan Grafted with Thermoresponsive Poly(di(ethylene glycol) Methyl Ether Methacrylate) for Cell Culture Applications

Chitosan is a polysaccharide extracted from animal sources such as crab and shrimp shells. In this work, chitosan films were modified by grafting them with a thermoresponsive polymer, poly(di(ethylene glycol) methyl ether methacrylate) (PMEO₂MA). The films were modified to introduce functional groups useful as reversible addition-fragmentation chain transfer (RAFT) agents. PMEO₂MA chains were then grown from the films via RAFT polymerization, making the chitosan films thermoresponsive. The degree of substitution of the chitosan-based RAFT agent and the amount of monomer added in the grafting reaction were varied to control the length of the grafted PMEO₂MA chain segments. The chains were cleaved from the film substrates for characterization using ¹H NMR and a gel permeation chromatography analysis. Temperature-dependent contact angle measurements were used to demonstrate that the hydrophilic-hydrophobic nature of the film surface varied with temperature. Due to the enhanced hydrophobic character of PMEO₂MA above its lower critical solution temperature (LCST), the ability of PMEO₂MA-grafted chitosan films to serve as a substrate for cell growth at 37 °C (incubation temperature) was tested. Interactions with cells (fibroblasts, macrophages, and corneal epithelial cells) were assessed. The modified chitosan films supported cell viability and proliferation. As the temperature is lowered to 4 °C (refrigeration temperature, below the LCST), the grafted chitosan films become less hydrophobic, and cell adhesion should decrease, facilitating their removal from the surface. Our results indicated that the cells were detached from the films following a short incubation period at 4 °C, were viable, and retained their ability to proliferate.

Antifracture, Antibacterial, and Anti-inflammatory Hydrogels Consisting of Silver-Embedded Curdlan Nanofibrils

The bacterial exopolysaccharide Curdlan has a unique collagen-like triple helical structure and immune-modulation activities. Although there have been several types of Curdlan gels reported for antibacterial or wound healing purposes, none of them exhibit favorable mechanical properties for clinically applicable wound healing materials. Herein, we present a two-step approach for preparing Ag-embedded Curdlan hydrogels that are highly soft but are very stretchable compared with common polysaccharide-based hydrogels. Ag ions were first reduced in a diluted Curdlan solution to form AgNP-decorated triple helices. Then, the aqueous solution consisting of Curdlan/Ag nanoparticles was mixed with a dimethyl sulfoxide solution consisting of a high concentration of Curdlan. This mixing triggered the conformation transformation of Curdlan random coils into triple helices, and then the helices were further packed into semicrystalline nanofibrils of ∼20 nm in diameter. Due to the presence of semicrystalline fibrils, this novel Curdlan hydrogel exhibits a fracture strain of ∼350% and fracture stress of ∼0.2 MPa at a water content of ∼97%. This nanofibril hydrogel supported the attachment, spreading, and growth of fibroblasts and effectively inhibited the growth of Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Moreover, the hydrogels downregulated NO production and proinflammatory gene expression levels in lipopolysaccharide (LPS)-stimulated macrophages but did not change the anti-inflammatory gene expression levels in IL-4-stimulated macrophages. In an animal study, these hydrogels accelerated wound healing in a bacteria-infected mice skin wound model. These results validate the further development of Curdlan/AgNPs nanofibril hydrogels in clinical wound management.

Recent advances of emerging green chitosan-based biomaterials with potential biomedical applications: A review

Chitosan is the most abundant natural biopolymer, after cellulose. It is mainly derived from the fungi, shrimp's shells, and exoskeleton of crustaceans, through the deacetylation of chitin. The ecological sustainability associated with its exercise and the flexibility of chitosan owing to its active functional hydroxyl and amino groups makes it a promising candidate for a wide range of applications through a variety of modifications. The biodegradability and biocompatibility of chitosan and its derivatives along with their various chemical functionalities make them promising carriers for pharmaceutical, nutritional, medicinal, environmental, agriculture, drug delivery, and biotechnology applications. The present work aims to provide a detailed and organized description of modified chitosan and its derivatives-based nanomaterials for biomedical applications. We addressed the biological and physicochemical benefits of nanocomposite materials made up of chitosan and its derivatives in various formulations, including improved physicochemical stability and cells/tissue interaction, controlled drug release, and increased bioavailability and efficacy in clinical practice. Moreover, several modification techniques and their effective utilization are also reviewed and collected in this review.

Multilayer fibroin/chitosan oligosaccharide lactate and pullulan immunomodulatory patch for treatment of hernia and prevention of intraperitoneal adhesion

This study aims to develop a novel intraperitoneal two- or three-layered patch with immunomodulatory property for treatment of hernia, regeneration of abdominal wall and prevention of intraperitoneal adhesions. Polypropylene (PP) mesh, middle layer, was intended to provide mechanical support whereas pullulan (PUL) hydrogel coating layer was designed to prevent intraperitoneal adhesions. Fibroin/chitosan oligosaccharide lactate (F/COS) layer electrospun on one side of pullulan was chosen for immunomodulation and abdominal wall regeneration. Physical and mechanical properties and regenerative capacity of intraperitoneal patches were determined. Immunomodulatory property of electrospun layer and whole patch was studied by determining nitric oxide amount produced by RAW 264.7 macrophages. 25 % (w/v) PUL hydrogel and F/COS with 90:10 (w/w) ratio yielded optimal results. Here, we report that fabricated intraperitoneal patches successfully prevented cell adhesion on one side and increased cell viability and proliferation on other side, along with immunomodulation, in vitro.

A Study of Combining Elastin in the Chitosan Electrospinning to Increase the Mechanical Strength and Bioactivity

While electrospun chitosan membranes modified to retain nanofibrous morphology have shown promise for use in guided bone regeneration applications in in vitro and in vivo studies, their mechanical tear strengths are lower than commercial collagen membranes. Elastin, a natural component of the extracellular matrix, is a protein with extensive elastic property. This work examined the incorporation of elastin into electrospun chitosan membranes to improve their mechanical tear strengths and to further mimic the native extracellular composition for guided bone regeneration (GBR) applications. In this work, hydrolyzed elastin (ES12, Elastin Products Company, USA) was added to a chitosan spinning solution from 0 to 4 wt% of chitosan. The chitosan-elastin (CE) membranes were examined for fiber morphology using SEM, hydrophobicity using water contact angle measurements, the mechanical tear strength under simulated surgical tacking, and compositions using Fourier-transform infrared spectroscopy (FTIR) and post-spinning protein extraction. In vitro experiments were conducted to evaluate the degradation in a lysozyme solution based on the mass loss and growth of fibroblastic cells. Chitosan membranes with elastin showed significantly thicker fiber diameters, lower water contact angles, up to 33% faster degradation rates, and up to seven times higher mechanical strengths than the chitosan membrane. The FTIR spectra showed stronger amide peaks at 1535 cm^-1 and 1655 cm^-1 in membranes with higher concentrated elastin, indicating the incorporation of elastin into electrospun fibers. The bicinchoninic acid (BCA) assay demonstrated an increase in protein concentration in proportion to the amount of elastin added to the CE membranes. In addition, all the CE membranes showed in vitro biocompatibility with the fibroblasts.

Gardenia jasminoides Ellis: Ethnopharmacology, phytochemistry, and pharmacological and industrial applications of an important traditional Chinese medicine

ETHNOPHARMACOLOGICAL RELEVANCE

Gardenia jasminoides Ellis is a popular shrub in the Rubiaceae family. The desiccative ripe fruits of this plant (called Zhizi in China) are well known and frequently used not only as an excellent natural colourant, but also as an important traditional medicine for the treatment of different diseases, such as reducing fire except vexed, clearing away heat evil, and cooling blood and eliminating stasis to activate blood circulation. It has also been declared as the first batch of dual-purpose plants used for food and medical functions in China.

AIM OF THE STUDY

This review aims to provide a critical and systematic summary of the traditional uses, ethnopharmacology, phytochemistry, pharmacology, toxicity and industrial applications of Gardenia jasminoides Ellis and briefly proposes several suggestions for future application prospects.

MATERIALS AND METHODS

The related information on Gardenia jasminoides Ellis was obtained from internationally recognized scientific databases through the Internet (PubMed, CNKI, Google Scholar, Baidu Scholar, Web of Science, Medline Plus, ACS, Elsevier and Flora of China) and libraries.

RESULTS

Approximately 162 chemical compounds have been isolated and identified from this herb. Among them, iridoid glycosides and yellow pigment are generally considered the main bioactive and characteristic ingredients. Various pharmacological properties, such as a beneficial effect on the nervous, cardiovascular and digestive systems, hepatoprotective activity, antidepressant activity, and anti-inflammatory activity, were also validated in vitro and in vivo. Moreover, geniposide and genipin are the most important iridoid compounds isolated from Gardenia jasminoides Ellis, and genipin is the aglycone of geniposide. As the predominant active ingredient with a distinct pharmacological activity, genipin is also an outstanding biological crosslinking agent. Gardenia yellow pigment has also been widely used as an excellent natural dye-stuff. Hence, Gardenia jasminoides Ellis has been applied to many other fields, including the food industry, textile industry and chemical industry, in addition to its predominant medicinal uses.

CONCLUSIONS

According to this review, Gardenia jasminoides Ellis is outstanding traditional medical plant used in medicine and food. Pharmacological investigations support the traditional use of this herb and may validate the folk medicinal use of Gardenia jasminoides Ellis to treat different diseases. Iridoid glycosides are potential medicines. Gardenia yellow pigment has been the most important source of a natural colourant for food, cloth and paint for thousands of years. This herb has made great contributions to human survival and development. Moreover, it has also achieved outstanding progress in human life and even in art. Although Gardenia jasminoides Ellis has extremely high and comprehensive utilization values, it is still far from being completely explored. Therefore, the comprehensive development of Gardenia jasminoides Ellis deserves further analysis.

Comparison of Attachment and Proliferation of Human Gingival Fibroblasts on Different Collagen Membranes

Background and Aim

Human gingival fibroblasts cultured on collagen membrane as an alternative treatment method used in tissue regeneration can lead to improved results in root coverage. The aim of this study was to evaluate the human gingival fibroblast proliferation and adhesion cultured on three types of collagen membranes.

Materials and Methods

In this in vitro study, first-line human gingival fibroblast cells (HGF1-RT1) prepared and cultured on three membranes, including porcine pericardium (PP) (Jason, Botiss dental), human pericardium (HP) (Regen, Faravardeh Baft Iranian), and glutaraldehyde cross-linked (GC) (BioMend Extend, Zimmer Dental). Cell survival was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) after 24, 48, and 72 h and 7 days. Furthermore, morphology and adhesion of cells on the membrane were evaluated after 1 and 7 days by electron microscopy (scanning electron microscopy [SEM]). Statistical analysis was performed using two-way ANOVA with a significance level of 0.05.

Results

Based on the results of MTT, cell survival on HP and PP membranes after 7 days significantly increased (P < 0.001), but for the GC membrane, it was reduced after 7 days (P = 0.031). Cell survival on HP and PP membranes did not differ (P = 1) and was more than GC (P < 0.001). SEM images showed that the adhesion of cells was better on HP and PP membranes than GC.

Conclusion

The results of this study showed that natural collagen membranes (HP and PP) similarly support proliferation and adhesion of gingival fibroblasts. Survival and adhesion of gingival fibroblasts on cross-linked collagen membrane was less than two other membranes.

Al-Doped chitosan nonwoven in a novel adsorption reactor with a cylindrical sleeve for dye removal: performance and mechanism of action

To overcome the inconvenience of solid/liquid separation of powdered adsorbents, a novel adsorption reactor with a cylinder sleeve was designed to match the textile-pattern of chitosan nonwoven for the sake of easy separation and simple operation.

Genipin-Crosslinked Chitosan Gels and Scaffolds for Tissue Engineering and Regeneration of Cartilage and Bone

The present review article intends to direct attention to the technological advances made since 2009 in the area of genipin-crosslinked chitosan (GEN-chitosan) hydrogels. After a concise introduction on the well recognized characteristics of medical grade chitosan and food grade genipin, the properties of GEN-chitosan obtained with a safe, spontaneous and irreversible chemical reaction, and the quality assessment of the gels are reviewed. The antibacterial activity of GEN-chitosan has been well assessed in the treatment of gastric infections supported by Helicobacter pylori. Therapies based on chitosan alginate crosslinked with genipin include stem cell transplantation, and development of contraction free biomaterials suitable for cartilage engineering. Collagen, gelatin and other proteins have been associated to said hydrogels in view of the regeneration of the cartilage. Viability and proliferation of fibroblasts were impressively enhanced upon addition of poly-l-lysine. The modulation of the osteocytes has been achieved in various ways by applying advanced technologies such as 3D-plotting and electrospinning of biomimetic scaffolds, with optional addition of nano hydroxyapatite to the formulations. A wealth of biotechnological advances and know-how has permitted reaching outstanding results in crucial areas such as cranio-facial surgery, orthopedics and dentistry. It is mandatory to use scaffolds fully characterized in terms of porosity, pore size, swelling, wettability, compressive strength, and degree of acetylation, if the osteogenic differentiation of human mesenchymal stem cells is sought: in fact, the novel characteristics imparted by GEN-chitosan must be simultaneously of physico-chemical and cytological nature. Owing to their high standard, the scientific publications dated 2010-2015 have met the expectations of an interdisciplinary audience.

Dimensionally stable and bioactive membrane for guided bone regeneration: An in vitro study

Composite fibrous electrospun membranes based on poly(dl-lactide) (PLA) and poly(ε-caprolactone) (PCL) were engineered to include borate bioactive glass (BBG) for the potential purposes of guided bone regeneration (GBR). The fibers were characterized using scanning and transmission electron microscopies, which respectively confirmed the submicron fibrous arrangement of the membranes and the successful incorporation of BBG particles. Selected mechanical properties of the membranes were evaluated using the suture pullout test. The addition of BBG at 10 wt % led to similar stiffness, but more importantly, it led to a significantly stronger (2.37 ± 0.51 N mm) membrane when compared with the commercially available Epiguide® (1.06 ± 0.24 N mm) under hydrated conditions. Stability (shrinkage) was determined after incubation in a phosphate buffer solution from 24 h up to 9 days. The dimensional stability of the PLA:PCL-based membranes with or without BBG incorporation (10.07-16.08%) was similar to that of Epiguide (14.28%). Cell proliferation assays demonstrated a higher rate of preosteoblasts proliferation on BBG-containing membranes (6.4-fold) over BBG-free membranes (4- to 5.8-fold) and EpiGuide (4.5-fold), following 7 days of in vitro culture. Collectively, our results demonstrated the ability to synthesize, via electrospinning, stable, polymer-based submicron fibrous BBG-containing membranes capable of sustaining osteoblastic attachment and proliferation-a promising attribute in GBR.

Weft-knitted silk-poly(lactide-co-glycolide) mesh scaffold combined with collagen matrix and seeded with mesenchymal stem cells for rabbit Achilles tendon repair

Natural silk fibroin fiber scaffolds have excellent mechanical properties, but degrade slowly. In this study, we used poly(lactide-co-glycolide) (PLGA, 10:90) fibers to adjust the overall degradation rate of the scaffolds and filled them with collagen to reserve space for cell growth. Silk fibroin-PLGA (36:64) mesh scaffolds were prepared using weft-knitting, filled with type I collagen, and incubated with rabbit autologous bone marrow-derived mesenchymal stem cells (MSCs). These scaffold-cells composites were implanted into rabbit Achilles tendon defects. At 16 weeks after implantation, morphological and histological observations showed formation of tendon-like tissues that expressed type I collagen mRNA and a uniformly dense distribution of collagen fibers. The maximum load of the regenerated Achilles tendon was 58.32% of normal Achilles tendon, which was significantly higher than control group without MSCs. These findings suggest that it is feasible to construct tissue engineered tendon using weft-knitted silk fibroin-PLGA fiber mesh/collagen matrix seeded with MSCs for rabbit Achilles tendon defect repair.

Composite mesoporous silica nanoparticle/chitosan nanofibers for bone tissue engineering

A novel MSN/CTS composite nanofibrous scaffold shows improved mechanical properties and enhances the attachment, proliferation and biomineralization of osteoblasts.

Emerging biomedical applications of nano-chitins and nano-chitosans obtained via advanced eco-friendly technologies from marine resources

The present review article is intended to direct attention to the technological advances made in the 2010-2014 quinquennium for the isolation and manufacture of nanofibrillar chitin and chitosan. Otherwise called nanocrystals or whiskers, n-chitin and n-chitosan are obtained either by mechanical chitin disassembly and fibrillation optionally assisted by sonication, or by e-spinning of solutions of polysaccharides often accompanied by poly(ethylene oxide) or poly(caprolactone). The biomedical areas where n-chitin may find applications include hemostasis and wound healing, regeneration of tissues such as joints and bones, cell culture, antimicrobial agents, and dermal protection. The biomedical applications of n-chitosan include epithelial tissue regeneration, bone and dental tissue regeneration, as well as protection against bacteria, fungi and viruses. It has been found that the nano size enhances the performances of chitins and chitosans in all cases considered, with no exceptions. Biotechnological approaches will boost the applications of the said safe, eco-friendly and benign nanomaterials not only in these fields, but also for biosensors and in targeted drug delivery areas.

Evaluation of biocompatibility and degradation of chitosan nanofiber membrane crosslinked with genipin

Chitosan, a natural polysaccharide, has demonstrated potential as a degradable biocompatible guided bone regeneration membrane. This study aimed to evaluate the in vivo biocompatibility and degradation of chitosan nanofiber membranes, with and without genipin crosslinking as compared with a commercial collagen membrane in rat model. Chitosan nanofiber membranes, with and without genipin crosslinking, and collagen membrane (control) were implanted subcutaneously in the backs of 30 rats. The membranes were analyzed histologically at 2, 4, 8, 12, 16, and 20 weeks. Sections were viewed and graded by a blinded pathologist using a 4-point scoring system (0 = absent, 1 = mild, 2 = moderate, and 3 = severe) to determine the tissue reaction to the membranes and to observe membrane degradation. There was no statistically significant difference in histological scores among chitosan and collagen membranes at different time points. Absence or minimal inflammation was observed in 57-74% of the membranes across all groups. Most chitosan membranes persisted for 16-20 weeks, whereas most collagen membranes disappeared by resorption at 12-16 weeks. The general tissue response to chitosan nanofiber membranes with and without genipin crosslinking, was similar to that of control commercial collagen membrane. However, the chitosan membranes exhibited slower degradation rates than collagen membranes.

Electrospun hydroxyapatite-containing chitosan nanofibers crosslinked with genipin for bone tissue engineering

Reconstruction of large bone defects remains problematic in orthopedic and craniofacial clinical practice. Autografts are limited in supply and are associated with donor site morbidity while other materials show poor integration with the host's own bone. This lack of integration is often due to the absence of periosteum, the outer layer of bone that contains osteoprogenitor cells and is critical for the growth and remodeling of bone tissue. In this study we developed a one-step platform to electrospin nanofibrous scaffolds from chitosan, which also contain hydroxyapatite nanoparticles and are crosslinked with genipin. We hypothesized that the resulting composite scaffolds represent a microenvironment that emulates the physical, mineralized structure and mechanical properties of non-weight bearing bone extracellular matrix while promoting osteoblast differentiation and maturation similar to the periosteum. The ultrastructure and physicochemical properties of the scaffolds were studied using scanning electron microscopy and spectroscopic techniques. The average fiber diameters of the electrospun scaffolds were 227 ± 154 nm as spun, and increased to 335 ± 119 nm after crosslinking with genipin. Analysis by X-ray diffraction, Fourier transformed infrared spectroscopy and energy dispersive spectroscopy confirmed the presence of characteristic features of hydroxyapatite in the composite chitosan fibers. The Young's modulus of the composite fibrous scaffolds was 142 ± 13 MPa, which is similar to that of the natural periosteum. Both pure chitosan scaffolds and composite hydroxyapatite-containing chitosan scaffolds supported adhesion, proliferation and osteogenic differentiation of mouse 7F2 osteoblast-like cells. Expression and enzymatic activity of alkaline phosphatase, an early osteogenic marker, were higher in cells cultured on the composite scaffolds as compared to pure chitosan scaffolds, reaching a significant, 2.4 fold, difference by day 14 (p < 0.05). Similarly, cells cultured on hydroxyapatite-containing scaffolds had the highest rate of osteonectin mRNA expression over 2 weeks, indicating enhanced osteoinductivity of the composite scaffolds. Our results suggest that crosslinking electrospun hydroxyapatite-containing chitosan with genipin yields bio-composite scaffolds, which combine non-weight-bearing bone mechanical properties with a periosteum-like environment. Such scaffolds will facilitate the proliferation, differentiation and maturation of osteoblast-like cells. We propose that these scaffolds might be useful for the repair and regeneration of maxillofacial defects and injuries.