Results of biomedical investigations of PHB and PHB/PHV fibers

The paper presents the results of biomedical investigations of sutures made of polyhydroxyalkanoates (PHAs) of two types (poly-3-hydroxybutyrate (PHB) and poly-3-hydroxybutyrate-co-poly-3-hydroxyvalerate (PHB/PHV)), synthesized by the bacteria Ralstonia eutropha B 5786 in the experiment on test animals in vivo, in comparison with silk and catgut sutures. PHB and PHB/PHV (PHBV) implants produced no adverse effect on physiological, biochemical and functional parameters of the animals during the post-surgery period. The tested PHA sutures featured the necessary strength throughout the healing period of the muscle-fascial cuts. The reaction of tissues to the implantation of PHB and PHB/PHV fibers fitted into the usual scheme characteristic of the wound process and of the reaction to a foreign-body invasion. This reaction and the reaction of tissues to silk had the similar nature and period of inflammation, but it was much less pronounced than the reaction to catgut. The tissue response to the implantation of PHAs consisted in a short-duration (up to 2 weeks) post-traumatic inflammation and the formation of a fibrous capsule less than 200 μm thick during weeks 4–8, which in 4–6 months was reduced to 40–60 μm in the course of reverse development. There were no adverse changes, such as suppurative inflammation, necrosis, calcification, and malignization of the cicatrice, at the site of implantation of PHA filaments, unlike in the cases with silk and catgut. In the case of PHA implantation there was a typical prolonged (throughout the post-surgery monitoring period) pronounced macrophagal stage with a large number of macrophages present. The macrophages were of the phagocytic type and multinucleate giant foreign cells, with a high activity of acid phosphomonoesterase that correlated with the activity of the enzyme in blood. Throughout the period of monitoring no differences in the tissue response to the implantation of the polymer filaments of two PHA types were recorded.