Tissue response to the implantation of biodegradable polyhydroxyalkanoate sutures

Polyhydroxyalkanoate (PHA) sutures were implanted to test animals intramuscularly, and tissue reaction was investigated and compared with the reaction to silk and catgut. Tested monofilament sutures made of PHAs of two types – polyhydroxybutyrate (PHB) and a copolymer of hydroxybutyrate and hydroxyvalerate (PHV) – featured the strength necessary for the healing of muscle-fascial wounds. The reaction of tissues to polymeric implants was similar to their reaction to silk and was less pronounced than the reaction to catgut; it was expressed in a transient post-traumatic inflammation (up to four weeks) and the formation of a fibrous capsule less than 200 μm thick, which became as thin as 40–60 μm after 16 weeks, in the course of reverse development. Macrophages and foreign-body giant cells with a high activity of acid phosphatase were actively involved in this process. PHB and PHB/PHV sutures implanted intramuscularly for an extended period (up to one year) did not cause any acute vascular reaction at the site of implantation or any adverse events, such as suppurative inflammation, necrosis, calcification of the fibrous capsule or malignant tumor formation. No statistically significant differences were revealed in the tissue response to polymer sutures of the two types. Capsules around silk and catgut sutures did not become significantly thinner.