Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) as an injectable implant system for prevention of post-surgical tissue adhesion

An injectable implant system that immediately forms a film around the injection site of an animal was successfully developed by dissolving microbial polyester poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) in not harmful organic solvents including N-methyl pyrrolidone (NMP), dimethylacetamide (DMAC), 1,4-dioxane (DIOX), dimethyl sulfoxide (DMSO) and 1,4-butanolide (BL), respectively. The formation of the PHBHHx film was the result of contact between aqueous body fluids and the amphiphilic PHBHHx solvents, leading to the controllable precipitation (film formation) of PHBHHx around the contact site. The resultant PHBHHx film assumed the shapes of its surrounding cavities. The resulting porous PHBHHx film was not favorable for attachment of Human Embryo Lung Fibroblast (HELF) cells. As a consequence, the fibroblasts cultured on the PHBHHx film exhibited a spheroid-like morphology. It was found that hydrophilicity of the PHBHHx film prepared using the above technique was significantly reduced compared with the poly(lactic acid) (PLA) film prepared for the same purpose and a PHBHHx film prepared from chloroform casting. This reduced hydrophilicity explains the poor attachment of fibroblast cells to the injectable PHBHHx film, suggesting that the PHBHHx injectable implant system can be developed as a tissue adhesion prevention film for surgical operations.