Chitosan is a biopolymer obtained from chitin, one of the most abundant and renewable materials on Earth Chitin is a primary component of cell walls in fungi, the exoskeletons of arthropods such as crustaceans, eg, crabs, lobsters and shrimps, and insects, the radulae of molluscs, cephalopod beaks, and the scales of fish and lissamphibians The discovery of chitin in 1811 is attributed to Henri Braconnot while the history of chitosan dates back to 1859 with the work of Charles Rouget The name of chitosan was, however, introduced in 1894 by Felix Hoppe-Seyler Chitosan has attracted major scientific and industrial interests from the late 1970s due to its particular macromolecular structure, biocompatibility, biodegradability and other intrinsic functional properties Chitosan and derivatives have practical applications in the food industry, agriculture, pharmacy, medicine, cosmetology, textile and paper industries, and in chemistry In recent years, chitosan has also received much attention in dentistry, ophthalmology, biomedicine and bioimaging, hygiene and personal care, veterinary medicine, packaging industry, agrochemistry, aquaculture, functional textiles and cosmetotextiles, catalysis, chromatography, beverage industry, photography, wastewater treatment and sludge dewatering, and biotechnology Nutraceuticals and cosmeceuticals are actually growing markets, and therapeutic and biomedical products should be the next markets in the development of chitosan Chitosan is also the object of numerous fundamental studies In this review, we highlight a selection of works on chitosan applications published over the past two decades

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Applications of chitosan in food, pharmaceuticals, medicine, cosmetics, agriculture, textiles, pulp and paper, biotechnology, and environmental chemistry

Chitosan, with a chemical structure similar to hyaluronic acid, has been implicated as a wound healing agent The purpose of this research was to evaluate the effect of chitosan on osteoblast differentiation and bone formation in vitro Mesenchymal stem cells were harvested from fetal Swiss Webster mice calvariae prior to osteoblast differentiation and calcification (12 to 13 days in utero) Stem cells were seeded into 6-well culture plates at a density of 350,000 cells per well Using this model, it was possible to quantify the influence of chitosan on osteoprogenitor differentiation and osteogenesis Experimental wells were pretreated with 200 microliters chitosan (2 mg/ml in 02% acetic acid vehicle) Control wells were pretreated with 200 microliters vehicle (02% acetic acid) or remained untreated Cells were allowed to grow under optimal conditions for 14 days Cell cultures were fixed with glutaraldehyde and stained with Von Kossa stain to identify bone forming colonies Positive staining colonies were identified and counted under light microscopy Histologic cross-sections of representative positively stained colonies identified osteoblasts and confirmed bone formation Examination of control wells revealed 36 +/- 06 colonies per well while experimental wells revealed a significantly greater average of 62 +/- 12 colonies per well (P < or = 001) Computer-assisted image analysis of the average area of bone formed by control colonies was 034 +/- 009 (relative units) while that of experimental colonies was 039 +/- 006 (relative units) per average bone forming colony The difference in mean size (control versus chitosan bone forming colony) was not statistically significant (P = 04691) The results of this in vitro experiment suggest that chitosan potentiates the differentiation of osteoprogenitor cells and may facilitate the formation of bone

Osteogenesis enhanced by chitosan (poly-N-acetyl glucosaminoglycan) in vitro

Chitin and chitosan are versatile polymers, where the interest in chitosan is due to the large variety of useful forms that are commercially available or can be made available. Chitin basically is obtained from prawn/crab shells; chemical treatment of chitin produces chitosan. This article surveys applications of chitin and chitosan in various industrial and biomedical fields.

Chitin and chitosan for versatile applications

Objective: To evaluate the periodontal tissue regenerative effects of a chitosan/collagen sponge applied to preclinical one-wall intrabony defects surgically created in beagle dogs.

Material and Methods:  4×4 mm one-wall intrabony defects were surgically created in the bilateral maxillary first and third, and the mandibular second and fourth premolars. The surgical control group received a flap operation only, while the buffer control group was treated afterwards with a phosphate-buffered saline/collagen sponge (CS) and the chitosan group was treated with a chitosan/cs. The subjects were killed 8 weeks after the operation, and a comparative histological examination was performed.

Results:  The amount of junctional epithelium migration was 2.30±1.24 mm in the surgical control group, 1.49±1.25 mm in the buffer control group, and 0.26±0.59 mm in the chitosan group. A significant difference was exhibited only between the surgical control and the chitosan group (p<0.05). The amount of connective tissue adhesion was 0.68±0.60, 1.07±0.91, and 0.41±0.42 mm in the surgical control, buffer control, and the chitosan group, respectively. The amount of cementum regeneration was 1.42±0.49, 1.60±0.41, and 3.46±0.78 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was seen between the chitosan group and the rest (p<0.01). The amount of alveolar bone regeneration was 1.00±0.77, 1.52±0.37, and 2.43±0.44 mm in the surgical control, buffer control, and the chitosan group, respectively. A significant difference was observed between the chitosan group and the rest (p<0.05).

Conclusion:  The results demonstrate the beneficial effect of the chitosan/cs on the one-wall intrabony defects of beagle dogs. The inhibited apical migration of epithelium and the increase in the amount of new bone and new cementum suggest the potency of chitosan in inducing periodontal tissue regeneration.

Eight-week histological analysis on the effect of chitosan on surgically created one-wall intrabony defects in beagle dogs

Introduction Thrombin is commonly used for activating the platelets and releasing the growth factors on the application of platelet-rich plasma (PRP). We have previously reported that chitosan can enhance rabbit platelet aggregation. In this study, the effects of chitosan on the subsequent growth factors release after human platelets activation were examined to evaluate the possibility of chitosan being used as a substitute for thrombin during PRP preparation. Material and methods Human platelet activation was determined by aggregation, adhesion and alpha-granule membrane glycoprotein expression. Platelet aggregation was measured by the turbidimetric method, the adhesion was directly examined on chitosan-coated glass plates under light microscope and scanning electron microscope (SEM), and the alpha-granule membrane glycoprotein was detected by fluorescent isothiocyanate (FITC)-conjugated anti-CD61 antibody through flow cytometry. The subsequent epidermal growth factor (EGF), platelet-derived growth factor (PDGF)-AB and transforming growth factor (TGF)-beta1 release from platelets were assayed by ELISA after mixing with chitosan. Results The enhancing effects on the platelet adhesion and the aggregation from chitosan were observed. Under both microscopes, the adhesive platelets on the chitosan-coated plates were not only greater in number but also earlier in activation than those on the control plates. With flow cytometry, increased glycoprotein IIIa expression in platelets was detected after chitosan treatment. Greater concentrations of growth factors were measured from PRP after chitosan treatment than after the solvent treatment. Conclusion Because of the observations of growth factors releasing from activated human platelets after chitosan stimulation, we suggest that chitosan may be an appropriate substitute for thrombin in PRP preparation.

Releasing growth factors from activated human platelets after chitosan stimulation: a possible bio-material for platelet-rich plasma preparation.

While the proposed uses of chitosan in medicine are numerous (1 – 7), no applications in dentistry have been reported so far. This might be due to the characteristics of the oral cavity, where various bacteria are constantly present and where lysozyme, a chitin degrading enzyme, occurs in the salivary secretion.

Chitosan in Dentistry

Glucosamine is one monomer of chitin and chitosan polymers, which have found applications in several fields of medicine and technology. This paper reports a study on the modifications induced by glucosamine molecules in the thermodynamical and structural properties of model membranes made of DPPC liposomes. Such effects were detected for molar ratios of monomer to lipid greater than 1:10, by using x-ray diffraction and calorimetric techniques. Suggestions are made on location of the molecules and on phase separation inside the bilayer, in analogy with the behaviour induced by small lipophilic molecules and cholesterol.

M. Emanuelli

Papers

Chitosan in Dentistry

Effects of Glucosamine on Model Membranes