Tissue-engineered products capable of enhancing wound healing

In a general wound healing process, foreign bodies and tissue detritus are broken down and then a new tissue is produced. However, the new tissue formation sometimes fails to proceed under the impaired conditions. The endogenous levels of growth factors are reduced in some chronic wounds. To improve these wound conditions, several types of tissue-engineered products composed of cell, growth factor, and/or biomaterial have been developed. This review includes the practical design of tissue-engineered products capable of enhancing wound healing. The first product is a cultured dermal substitute composed of cell and biomaterial. The cultured dermal substitute is prepared by seeding allogeneic fibroblasts into a hyaluronic acid and collagen spongy sheet. Although allogeneic fibroblasts are rejected gradually in immune system, they are able to release some types of growth factors, and thereby regenerate a damaged tissue. The second products are a wound dressing and a skin care product composed of growth factor and biomaterial. These products are prepared by freeze-drying an aqueous solution of hyaluronic acid and collagen containing epidermal growth factor. Epidermal growth factor is beneficial for wound healing because of its effects on proliferation of keratinocytes and fibroblasts, thus capable of facilitating granulation tissue formation and re-epithelialization. In addition, epidermal growth factor can stimulate fibroblasts to synthesize an increased amount of vascular endothelial growth factor and hepatocyte growth factor that are essential for angiogenesis. The third product is an anti-adhesive product composed of growth factor and biomaterial. This product is prepared by freeze-drying an aqueous solution of hyaluronic acid and collagen containing epidermal growth factor. Wound dressings are applied to external wounds, while anti-adhesive products are applied to internal wounds. However, both products should be designed to have a common function that facilitates wound healing.