Cytotoxicity and immunogenicity of SACCHACHITIN and its mechanism of action on skin wound healing

SACCHACHITIN membrane, a weavable skin substitute made from the residual fr uiting body of Ganoderma tsugae, has been demonstrated to promote skin woun d healing. Prior to its clinical application, it is critical to learn more about any possible cytotoxicity, immunogenicity, or allergy response, and a t least some of its mechanism(s) of action(s). In the present studies, it h as been found that SACCHACHITIN suspension at less than 0.05% shows no cyto toxicity to the primary culture of rat fibroblasts. However, at higher conc entrations (greater than or equal to0.1%), it does reduce the growth of fib roblasts, based on MTT assays. This might be caused by positive charges on chitin molecules that are too strong, and may be harmful to the cell membra ne. SACCHACHITIN showed no immunogenicity after it was inoculated into rats three times; however, the unmodified, purified rabbit type I and type II c ollagens did. Subcutaneous injection of SACCHACHITIN suspension into rats s howed no gross allergic responses on skin. Nevertheless, it did cause local acute inflammation, as observed by histological investigation. This is sim ilar to what occurred in the wound site covered with SACCHACHITIN membrane. The chemotactic effect of SACCHACHITIN was exhibited in both intact and wo unded skin tissues. This may be one of the initial beneficial effects of SA CCHACHITIN membrane to wound healing. The rapid acute inflammatory process was followed by the appearance of angiogenesis and granulation tissue forma tion, which occurred earlier than it normally would. Coverage of the wound area with SACCHACHITIN membrane also induced an earlier formation of scar t issue to replace the granulation tissue. A 1.5 x 1.5 cm(2) wound area cover ed by SACCHACHITIN completely healed by 21 days, while that covered with co tton gauze did not. Therefore, SACCHACHITIN is a safe biomaterial for use a s a wound dressing for skin healing. Its promoting action for wound healing might be due to its chemotactic effect for inflammatory cells. This, in tu rn, may facilitate subsequent angiogenesis, granulation tissue formation, a nd faster new tissue formation, leading to faster wound healing. (C) 2001 J ohn Wiley & Sons, Inc.