Photoinduced prevention of tissue adhesion.

Postoperative tissue adhesion causes retarded wound healing and the need for reoperation; it can even be life threatening. In this report, the authors present prototype materials and performance of newly developed tissue adhesion prevention technology based on photocurable polysaccharides. Polysaccharides used were hyaluronic acid and chondroitin sulfate, both of which were partially derived with photoreactive groups such as cinnamoyl, coumarin, and thymine. Photoreactive hyaluronic acids with low degrees of derivatization were soluble in water. Films of cinnamated hyaluronic acid or an aqueous solution of cinnamated chondroitin sulfate were photocured by ultraviolet irradiation, resulting in water adsorbable films or water swollen gels, respectively. Gelation was due to intermolecular dimerization between cinnamoyl groups. The authors provide two potentially applicable examples: 1) a photocured, water swollen hydrogel film, and 2) a photocurable chondroitin sulfate buffer solution. The authors used hydrogel films to cover the peritoneum after mechanically injuring its surface. Histologic examination showed neither tissue nor cell adhesion, and only a minimal inflammatory response. When tissues were coated with a photocurable chondroitin sulfate solution, the viscous solution was converted to a hydrogel upon ultraviolet irradiation, resulting in in situ tissue covering. Although an optimal molecular design has not yet been found, unique features of mucopolysaccharides (e.g., high water uptake; biodegradability and bioresorbability; and nontoxicity of photodimerizable groups) may result in the development of photoinduced tissue adhesion prevention technology.