Chitosan-hyaluronan/nano chondroitin sulfate ternary composite sponges for medical use

Controlled local drug delivery strategies from chitosan hydrogels for wound healing

INTRODUCTION

The main target of tissue engineering is the preparation and application of adequate materials for the design and production of scaffolds, that possess properties promoting cell adhesion, proliferation and differentiation. The use of natural polysaccharides, such as chitosan, to prepare hydrogels for wound healing and controlled drug delivery is a research topic of wide and increasing interest. Areas covered: This review presents the latest results and challenges in the preparation of chitosan and chitosan-based scaffold/hydrogel for wound healing applications. A detailed overview of their behavior in terms of controlled drug delivery, divided by drug categories, and efficacy was provided and critically discussed. Expert opinion: The need to establish and exploit the advantages of natural biomaterials in combination with active compounds is playing a pivotal role in the regenerative medicine fields. The challenges posed by the many variables affecting tissue repair and regeneration need to be standardized and adhere to recognized guidelines to improve the quality of evidence in the wound healing process. Currently, different methodologies are followed to prepare innovative scaffold formulations and structures. Innovative technologies such as 3D printing or bio-electrospray are promising to create chitosan-based scaffolds with finely controlled structures with customizable shape porosity and thickness. Chitosan scaffolds could be designed in combination with a variety of polysaccharides or active compounds with selected and reproducible spacial distribution, providing active wound dressing with highly tunable controlled drug delivery.

Layered chitosan-collagen hydrogel/aligned PLLA nanofiber construct for flexor tendon regeneration

The aim of our study was to develop a tendon construct of electrospun aligned poly (l-lactic acid) (PLLA) nanofibers, to mimic the aligned collagen fiber bundles and layering PLLA fibers with chitosan-collagen hydrogel, to mimic the glycosaminoglycans of sheath ECM for tendon regeneration. The hydrogel coated electrospun membrane was rolled and an outer coating of alginate gel was given to prevent peritendinous adhesion. The developed constructs were characterized by SEM, FT-IR and tensile testing. Protein adsorption studies showed lower protein adsorption on coated scaffolds compared to uncoated scaffolds. The samples were proven to be non-toxic to tenocytes. The chitosan-collagen/PLLA uncoated scaffolds and alginate gel coated chitosan-collagen/PLLA scaffolds showed good cell proliferation. The tenocytes showed good attachment and spreading on the scaffolds. This study indicated that the developed chitosan-collagen/PLLA/alginate scaffold would be suitable for flexor tendon regeneration.

Heterogeneity of Scaffold Biomaterials in Tissue Engineering

Tissue engineering (TE) offers a potential solution for the shortage of transplantable organs and the need for novel methods of tissue repair. Methods of TE have advanced significantly in recent years, but there are challenges to using engineered tissues and organs including but not limited to: biocompatibility, immunogenicity, biodegradation, and toxicity. Analysis of biomaterials used as scaffolds may, however, elucidate how TE can be enhanced. Ideally, biomaterials should closely mimic the characteristics of desired organ, their function and their in vivo environments. A review of biomaterials used in TE highlighted natural polymers, synthetic polymers, and decellularized organs as sources of scaffolding. Studies of discarded organs supported that decellularization offers a remedy to reducing waste of donor organs, but does not yet provide an effective solution to organ demand because it has shown varied success in vivo depending on organ complexity and physiological requirements. Review of polymer-based scaffolds revealed that a composite scaffold formed by copolymerization is more effective than single polymer scaffolds because it allows copolymers to offset disadvantages a single polymer may possess. Selection of biomaterials for use in TE is essential for transplant success. There is not, however, a singular biomaterial that is universally optimal.

Evaluation of polypropylene mesh coated with biological hydrogels for temporary closure of open abdomen

Polypropylene mesh, as a temporary abdominal closure device, may cause mechanical intestine injury and inflammatory response. Chitosan/gelatin hydrogel has excellent biocompatibility, soft and elastic properties. This work is to assess the effects of the chitosan/gelatin hydrogel coated polypropylene mesh on open abdomen wounds. Histological analysis and detection of healing-related factors were conducted to evaluate the inflammation and wound healing process. After 1-day implantation in a murine model of open abdomen, the coated polypropylene mesh, compared with simple polypropylene mesh, demonstrated well protection of the intestine serosa. After 14-day implantation, it reduced the inflammation response by down-regulating the cytokines interleukin-6 and tumor necrosis factor-α, and up-regulating the anti-inflammatory factor interleukin-10. Meanwhile, the composite stimulated granulation tissue growth, and promoted matrix deposition and angiogenesis after 7 and 14 days. In conclusion, the modified temporary abdominal closure composite could significantly protect the intestines from mechanical damage and accelerate wound healing.

New antimicrobial chitosan derivatives for wound dressing applications

Chitosan is a non-toxic, biocompatible, biodegradable natural cationic polymer known for its low imunogenicity, antimicrobial, antioxidant effects and wound-healing activity. To improve its therapeutic potential, new chitosan-sulfonamide derivatives have been designed to develop new wound dressing biomaterials. The structural, morphological and physico-chemical properties of synthesized chitosan derivatives were analyzed by FT-IR, (1)H NMR spectroscopy, scanning electron microscopy, swelling ability and porosity. Antimicrobial, in vivo testing and biodegradation behavior have been also performed. The chitosan derivative membranes showed improved swelling and biodegradation rate, which are important characteristics required for the wound healing process. The antimicrobial assay evidenced that chitosan-based sulfadiazine, sulfadimethoxine and sulfamethoxazole derivatives were the most active. The MTT assay showed that some of chitosan derivatives are nontoxic. Furthermore, the in vivo study on burn wound model induced in Wistar rats demonstrated an improved healing effect and enhanced epithelialization of chitosan-sulfonamide derivatives compared to neat chitosan. The obtained results strongly recommend the use of some of the newly developed chitosan derivatives as antimicrobial wound dressing biomaterials.

Norfloxacin-loaded collagen/chitosan scaffolds for skin reconstruction: Preparation, evaluation and in-vivo wound healing assessment

Biomaterial scaffolds are versatile tools as drug carrier for treatment of wounds. A series of norfloxacin-loaded scaffolds were synthesized for treatment of wounds by combining collagen with two different types of chitosan using freeze-drying technique. Subsequently, scaffolds were screened in terms of morphology, water absorption and retention capacity, biodegradation, ex-vivo bioadhesive strength, in-vitro drug release biological compatibility, X-ray diffractometry, differential scanning calorimetry as well as in-vivo evaluation. The results indicate that the scaffold mechanical strength is dependent on the type of used chitosan. The prepared scaffolds contained interconnected porous architecture. The scaffolds had high water uptake and retention capacity with extended biodegradation rate. Scaffolds prepared with chitosan HCl showed superior bioadhesive strength compared to those prepared with low molecular weight chitosan. All scaffolds showed almost 100% drug release within 24h. As identified by the terahertz pulsed imaging measurements, there is single scaffold area with the same concentration. After 28 days of wound dressing with selected norfoloxacin-loaded or unloaded collagen/chitosan scaffolds in Albino rats, it was found that the tissue regeneration time was fast compared to non-treated wounds. Furthermore, the drug-loaded scaffolds showed normal structure of an intact epidermal layer as well as the underlying dermis as revealed by histopathological studies. The obtained results suggest that the investigated norfloxacin-loaded collagen/chitosan scaffold is a potential candidate for skin regeneration application.

Advanced Therapeutic Dressings for Effective Wound Healing--A Review

Advanced therapeutic dressings that take active part in wound healing to achieve rapid and complete healing of chronic wounds is of current research interest. There is a desire for novel strategies to achieve expeditious wound healing because of the enormous financial burden worldwide. This paper reviews the current state of wound healing and wound management products, with emphasis on the demand for more advanced forms of wound therapy and some of the current challenges and driving forces behind this demand. The paper reviews information mainly from peer-reviewed literature and other publicly available sources such as the US FDA. A major focus is the treatment of chronic wounds including amputations, diabetic and leg ulcers, pressure sores, and surgical and traumatic wounds (e.g., accidents and burns) where patient immunity is low and the risk of infections and complications are high. The main dressings include medicated moist dressings, tissue-engineered substitutes, biomaterials-based biological dressings, biological and naturally derived dressings, medicated sutures, and various combinations of the above classes. Finally, the review briefly discusses possible prospects of advanced wound healing including some of the emerging physical approaches such as hyperbaric oxygen, negative pressure wound therapy and laser wound healing, in routine clinical care.

Composite hydrogel of chitosan-poly(hydroxybutyrate-co-valerate) with chondroitin sulfate nanoparticles for nucleus pulposus tissue engineering

Intervertebral disc degeneration, occurring mainly in nucleus pulposus (NP), is a leading cause of low back pain. In seeking to mitigate this condition, investigators in the field of NP tissue engineering have increasingly studied the use of hydrogels. However, these hydrogels should possess appropriate mechanical strength and swelling pressure, and concurrently support the proliferation of chondrocyte-like cells. The objective of this study was to develop and validate a composite hydrogel for NP tissue engineering, made of chitosan-poly(hydroxybutyrate-co-valerate) (CP) with chondroitin sulfate (CS) nanoparticles, without using a cross linker. The water uptake ability, as well as the viscoelastic properties of this composite hydrogel, was similar to native tissue, as reflected in the complex shear modulus and stress relaxation values. The hydrogel could withstand varying stress corresponding to daily activities like lying down (0.01 MPa), sitting (0.5 MPa) and standing (1.0 MPa) under dynamic conditions. The hydrogels were stable in PBS for 2 weeks and its stiffness, elastic and viscous modulus did not alter significantly during this period. Both CP and CP-CS hydrogels could assist the viability and adhesion of adipose derived rat mesenchymal stem cells (ADMSCs). The viability and chondrogenic differentiation of MSCs was significantly enhanced in presence of CS nanoparticles. Thus, CS nanoparticles-incorporated chitosan-PHBV hydrogels offer great potential for NP tissue engineering.

Comparison of two proanthocyanidin cross-linked recombinant human collagen-peptide (RHC) - chitosan scaffolds

Cross-linking plays an important role in tissue engineering, which involves the alternative of cross-linker and the way of components interaction. We compared two proanthocyanidin (PA) cross-linked recombinant human collagen-peptide - chitosan scaffolds: immerse cross-linking (I-CLS) and premix cross-linking (P-CLS). Both of the scaffolds presented homogeneous pore structure with mean pore size of 110-115 μm. The swelling ratio was decreased to 29.6 in I-CLS, but increased to 37.1 in P-CLS while porosity of the two scaffolds was reduced about 8% comparing to 94.3% before cross-linking. The cross-linked scaffolds exhibited enhanced resistance to enzyme degradation and improved compressive modulus (I-CLS > P-CLS). The scaffolds transformed from elastic region to plastic region until the strain reached 60%, and the stress was 40.5, 133.2 and 84.1 kPa of uncross-linking scaffold, I-CLS and P-CLS individually. Thermal stability indicated molecular bonding between PA and the scaffold components, simultaneously, Fourier transform infrared spectroscopy mainly presented hydrogen bonding between the protein amide carbonyl and the phenolic hydroxyl with a particular transform due to pyrrolidine rings of proline in P-CLS. Both of the I-CLS and P-CLS could promote human umbilical vein endothelial cells attachment and proliferation. The characterization suggested in situ biodegradable application of P-CLS, while a potential long-term utilization of I-CLS in tissue engineering.

Preparation and characterization of silver nanoparticle loaded amorphous hydrogel of carboxymethylcellulose for infected wounds

There is a growing demand for an appropriate and safe antimicrobial dressing to treat infected deep wounds. An amorphous gel formulation (SNP-CMC), containing silver nanoparticles (SNPs) and carboxymethylcellulose (CMC), was prepared in one step by the reduction of silver nitrate in situ. Spectrophotometric and microscopic analysis revealed that the SNPs were 7-21 nm in diameter. In simulated wound experiments, SNP-CMC gel was found to absorb 80.48 ± 4.69% w/w of saline and donate 17.43 ± 0.76% w/w of moisture within 24h indicating its dual fluid affinity. Cytocompatibility of the gel was assessed by proliferation studies with primary human skin cells. The antimicrobial activity studies showed that SNP-CMC containing 50 ppm of SNPs was effective against the growth of both Gram negative and Gram positive strains including methicillin-resistant Staphylococcus aureus (MRSA). These results indicate that SNP-CMC could be ideal for the treatment of deep infected wounds.

Polysaccharide-coated PCL nanofibers for wound dressing applications

Polysaccharide-based nanofibers with a multilayered structure are prepared by combining electrospinning (ESP) and layer-by-layer (LBL) deposition techniques. Charged nanofibers are firstly prepared by electrospinning poly(ε-caprolactone) (PCL) with a block-copolymer bearing carboxylic acid functions. After deprotonation of the acid groups, the layer-by-layer deposition of polyelectrolyte polysaccharides, notably chitosan and hyaluronic acid, is used to coat the electrospun fibers. A multilayered structure is achieved by alternating the deposition of the positively charged chitosan with the deposition of a negatively charged polyelectrolyte. The construction of this multilayered structure is followed by Zeta potential measurements, and confirmed by observation of hollow nanofibers resulting from the dissolution of the PCL core in a selective solvent. These novel polysaccharide-coated PCL fiber mats remarkably combine the mechanical resistance typical of the core material (PCL)-particularly in the hydrated state-with the surface properties of chitosan. The control of the nanofiber structure offered by the electrospinning technology, makes the developed process very promising to precisely design biomaterials for tissue engineering. Preliminary cell culture tests corroborate the potential use of such system in wound healing applications.

Paclitaxel loaded hyaluronic acid nanoparticles for targeted cancer therapy: in vitro and in vivo analysis

The main aim of this work was to evaluate a nanoconjugate system of paclitaxel loaded self-assembling, biodegradable micelles for targeting CD44 overexpression in cancer cells. The shape and size, zeta potential, encapsulation efficiency and cell uptake of these drug-loaded micelles were evaluated. To understand their bio distribution profile, the hyaluronate (HA) micelles were labeled with Flamma™-774 NIR dye and injected into SCC7 tumor induced mice. Cell viability in response to drug loaded and unloaded micelles was studied in SCC7 cancer cells using the MTS assay. An in vivo tumor inhibition study was conducted by intravenous injection of paclitaxel-loaded HA micelle nanoparticles as well as control nanoparticles without paclitaxel. The shape of the nanomicelles was evaluated by loading them with hydrophobic superparamagnetic iron oxide nanoparticle and then visualizing them by TEM. In conclusion, paclitaxel-loaded HA nanoparticulate micelles might be found to be a specific and efficient chemotherapeutic treatment for CD44 overexpressing cancer cells.

Transdentinal cytotoxicity of carbodiimide (EDC) and glutaraldehyde on odontoblast-like cells

OBJECTIVE

To evaluate the transdentinal cytotoxicity of three different concentrations of carbodiimide (EDC) or 5% glutaraldehyde (GA) on MDPC-23 cells.

METHODS

Seventy 0.4-mm-thick dentin disks obtained from human molars were adapted to artificial pulp chambers. MDPC-23 cells were seeded on the pulpal surface of the disks. After 48 hours, the occlusal dentin was acid-etched and treated for 60 seconds with one of the following solutions (n=10): no treatment (negative control); 0.1 M, 0.3 M, or 0.5 M EDC; 5% GA; Sorensen buffer; or 29% hydrogen peroxide (positive control). Cell viability and morphology were assessed by methyltetrazolium assay and scanning electron microscopy (SEM), respectively. The eluates were collected after the treatments and applied on MDPC-23 seeded in a 24-well plate to analyze cell death, total protein (TP), and collagen production. The last two tests were performed 24 hours and seven days after the challenge. Data were analyzed by Kruskal-Wallis and Mann-Whitney tests (p<0.05).

RESULTS

EDC at all test concentrations did not reduce cell viability, while 5% GA did increase cell metabolism. Cell death by necrosis was not elicited by EDC or 5% GA. At the 24-hour period, 0.3 M and 0.5 M EDC reduced TP production by 18% and 36.8%, respectively. At seven days, increased TP production was observed in all groups. Collagen production at the 24-hour period was reduced when 0.5 M EDC was used. After seven days, no difference was observed among the groups. SEM showed no alteration in cell morphology or number, except in the hydrogen peroxide group.

CONCLUSIONS

Treatment of acid-etched dentin with EDC or GA did not cause transdentinal cytotoxic effects on odontoblast-like cells.

Fabrication and Characterization of Macroporous Chitosan/PVA Composite Sponges for Wound Dressing

The present investigation involves the synthesis of chitosan based composite sponges in view of their applications in wound dressing, antibacterial and haemostatic. A facile CO2 bubbles template freeze-drying method was developed for the fabrication of macroporous chitosan- poly(vinyl alcohol) (PVA) composite sponges with a typical porosity of 50% and pore size of 100-300 µm. The composite sponges show a high water absorption rate up to 60 times of its weight and a water vapor transmission rate of 30 ∼ 70g/m2 • h. Effects of the content of cross-linking agent and PVA on mechanical properties and moisture permeability were examined. Improved strength and flexibility of the chitosan sponges were observed with the presence of PVA. Further, the antibacterial and haemostatic activities have been demonstrated. The Chitosan/PVA sponges of high liquid absorption, appropriate moisture permeability, excellent antimicrobial and haemostatic activities have a great potential for wound dressing applications.

The improvement of hemostatic and wound healing property of chitosan by halloysite nanotubes

The addition of halloysite nanotubes into chitosan sponges can simultaneously improve the mechanical, hemostatic and wound healing property of chitosan.

Chitosan-hyaluronic acid/nano silver composite sponges for drug resistant bacteria infected diabetic wounds

The aim of this work was to develop an antimicrobial sponge composed of chitosan, hyaluronic acid (HA) and nano silver (nAg) as a wound dressing for diabetic foot ulcers (DFU) infected with drug resistant bacteria. nAg (5-20 nm) was prepared and characterized. The nanocomposite sponges were prepared by homogenous mixing of chitosan, HA and nAg followed by freeze drying to obtain a flexible and porous structure. The prepared sponges were characterized using SEM and FT-IR. The porosity, swelling, biodegradation and haemostatic potential of the sponges were also studied. Antibacterial activity of the prepared sponges was analysed using Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa and Klebsiella pneumonia. Chitosan-HA/nAg composite sponges showed potent antimicrobial property against the tested organisms. Sponges containing higher nAg (0.005%, 0.01% and 0.02%) concentrations showed antibacterial activity against MRSA. Cytotoxicity and cell attachment studies were done using human dermal fibroblast cells. The nanocomposite sponges showed a nAg concentration dependent toxicity towards fibroblast cells. Our results suggest that this nanocomposite sponges could be used as a potential material for wound dressing for DFU infected with antibiotic resistant bacteria if the optimal concentration of nAg exhibiting antibacterial action with least toxicity towards mammalian cells is identified.