Chitin (β-(1-4)-poly-N-acetyl-d-glucosamine) is widely distributed in nature and is the second most abundant polysaccharide after cellulose. It is often converted to its more deacetylated derivative, chitosan. Previously, many reports have indicated the accelerating effects of chitin, chitosan, and its derivatives on wound healing. More recently, chemically modified or nano-fibrous chitin and chitosan have been developed, and their effects on wound healing have been evaluated. In this review, the studies on the wound-healing effects of chitin, chitosan, and its derivatives are summarized. Moreover, the development of adhesive-based chitin and chitosan are also described. The evidence indicates that chitin, chitosan, and its derivatives are beneficial for the wound healing process. More recently, it is also indicate that some nano-based materials from chitin and chitosan are beneficial than chitin and chitosan for wound healing. Clinical applications of nano-based chitin and chitosan are also expected.

Previous reports indicate that N-acetyl-d-glucosamine oligomers (chitin oligosaccharide; NACOS) and d-glucosamine oligomers (chitosan oligosaccharide; COS) have various biological activities, especially against cancer and inflammation. In this review, we have summarized the findings of previous investigations that have focused on anticancer or anti-inflammatory properties of NACOS and COS. Moreover, we have introduced recent evaluation of NACOS and COS as functional foods against cancer and inflammatory disease.

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A histochemical and immunohistochemical study of five cases of extra-ocular sebaceous carcinoma was performed using formalin-fixed and paraffin-embedded tissue specimens. Histochemically, the clear cells of sebaceous carcinomas were negative with periodic acid-Schiff and alcian blue staining. Immunohistochemically, the tumour cells of sebaceous carcinomas showed positive reactions for epithelial membrane antigen, human milk fat globules subclass 1, human milk fat globules subclass 2 and Leu M1, but did not express carcinoembryonic antigen, breast carcinoma associated antigen, S-100 protein, gross cystic disease fluid protein-15 or Dako M1. These histochemical and immunohistochemical findings were compared with those of other skin cancers which must be distinguished histopathologically from sebaceous carcinoma. We conclude that sebaceous carcinoma can be distinguished from eccrine porocarcinoma, malignant clear cell hidradenoma, extramammary Paget's disease, malignant trichilemmoma, squamous cell carcinoma and basal cell carcinoma by histochemical and immunohistochemical techniques using formalin-fixed and paraffin-embedded tissue specimens.

Whole human scalp hair follicles were cultured. The follicles were dissected from skin pieces of normal scalp and put into 1.5 ml of incubation medium in a closed 5 ml glass tube under an atmosphere of 95% O2 and 5% CO2. The tube was rolled at 15 rpm at 36 degrees C. Remarkable hair growth was noticed for 7 to 8 days. Hair root sheaths also grew with the hair shafts. The structure of the hair bulbs was well maintained for at least 6 days, and then the hair matrix cells started to degenerate. Fetal calf serum was not essential for hair growth in vitro, but increased the growth rate slowly. Testosterone and oestrogen inhibited hair growth in vitro to a similar extent. The minimum effective doses of both hormones to suppress hair growth were around 5 ng/ml, which corresponds well to the normal plasma level of testosterone in adult males in vivo, suggesting that scalp hair growth may be critically controlled by testosterone in adult males.

We evaluated the anti-tumor activities of the oral administration of fucoidan extracted from Cladosiphon okamuranus using a tumor (colon 26)-bearing mouse model. The materials used included low-molecular-weight fucoidan (LMWF: 6.5–40 kDa), intermediate-molecular-weight fucoidan (IMWF: 110–138 kDa) and high-molecular-weight fucoidan (HMWF: 300–330 kDa). The IMWF group showed significantly suppressed tumor growth. The LMWF and HMWF groups showed significantly increased survival times compared with that observed in the control group (mice fed a fucoidan-free diet). The median survival times in the control, LMWF, IMWF and HMWF groups were 23, 46, 40 and 43 days, respectively. It was also found that oral administration of fucoidan increased the population of natural killer cells in the spleen. Furthermore, from the results of the experiment using Myd-88 knockout mice, it was found that these effects are related to gut immunity. These results suggest that fucoidan is a candidate anti-tumor functional food.

Previous reports indicate that the beneficial effect of chitin nanofibrils (CNFs), and chitosan nanofibrils (CSNFs) for wound healing. In this study, the wound healing effects of superficially deacetylated chitin nanofibrils (SDACNFs) were evaluated using an experimental model. In the experiments using circular excision wound model, SDACNFs induced re-epithelium and proliferation of the fibroblasts and collagen tissue. In the chitin, CNFs, and CSNFs, on the other hand, the e-epithelium and proliferation of the fibroblasts and collagen tissue were not induced perfectly compared with the SDACNFs group. In particular, re-epithelization was observed on day 4 in the only SDACNF group. Moreover, SDACNFs did not induce severe systemic inflammation in the linear incision wound model. The data indicated that SDACNFs effectively induced the proliferation and re-modeling phases compared with chitin, CNFs, and CSNFs in the wound. These data indicate that SDACNFs can be beneficial as a new biomaterial for wound healing.