Biomedical Applications – WOUND HEALING
The beneficial roles of chitin and its derivative, chitosan, in potentiating healing in mammals and humans have been surmised since antiquity and firmly established in the last 25 years. The ancient Koreans used octopus pen chitin for abrasion treatment. Mexicans have traditionally employed preparations from mushrooms, with their chitin/chitosan cell walls, to aid healing of deep cuts.
The scientific basis for the utility of the monomer sugar N-acetylglucosamine (NAG) in the promotion of wound healing was officially documented in 1960 (1). By the 1970s, highly enhanced rates of wound healing observed with polymeric forms of chitin were reported widely by Balassa, Prudden and co-workers (2, 3) and the subject of US Patents (4, 5, 6).
Easier to use, chitosan was also studied and shown effective in wound healing stimulation by Balassa and Prudden (3). Allan, et al. (7) reported effective burn treatments in rats using chitosan acetate. Tough, protective chitosan acetate films had the healing advantages of good oxygen permeability, high water absorptivity and slow enzymatic (lysozyme) degradation, thus avoiding the need for repeated removal. Malette, et al. (8, 22) showed that treating various dog tissues with chitosan solution resulted in the inhibition of fibroplasia and enhanced tissue regeneration. Muzzarelli, et al. (9) used chitosan and chitosan ascorbate to replace dura mater in cats and reported complete polymer disappearance and normal tissue regeneration in 60 days. Borah, et al. (14) have reported accelerated wound epithelialization in rabbits with N,O-carboxymethyl chitosan.
With advances in chitin polymer technology (10, 11), Unitika, Ltd. (Japan) has developed, gained approval and marketed in Japan a non-woven fabric dressing, Beschitin W, for treatment of human traumatic skin wounds and burns, including deep dermal burns. It has been shown to have superior performance in relief of pain, speed of healing, wound adherence, exudate absorbtion and scar minimization (12, 13). Unitika also has reported clinical results showing good biocompatibility and efficacy for a porous chitin sponge used as a temporary deep wound dressing (15). Other Japanese firms have developed spun chitosan fiber materials as prototype wound dressings.
Significant progress in veterinary wound healing has been reported recently. Minami, et al. (16) noted accelerated regeneration of tissue with no visible scarring in treating various types of infected livestock wounds with chitin/polyester non-woven dressings, chitin-cotton and chitosan-cotton wound filling materials. Similar results were observed with domestic pets utilizing the same materials (17). Supported by these findings, Sunfive, Inc. (Japan) has developed and marketed a chitosan-cotton, Chitopak™ C, and a chitosan suspension, Chitofine™ S, whose efficacy 'is corroborated by post-market reports (18, 19).
INTERNATIONAL COMMISSION ON NATURAL HEALTH PRODUCTS