Morphological changes in the skin after subdermal implantation of monofilament polydioxanone threads

Background. In this study, we evaluated morphological changes in tissues of experimental animals in response to subdermal implantation of monofilament polydioxanone threads. This technique has become popular relatively recently; it is aimed at the prevention and correction of age-related skin changes. Objective: to analyze morphological changes in the skin after subdermal implantation of monofilament polydioxanone threads. Material and methods. Thread implantation is performed by injecting the conductor needle and a monofilament polydioxanone thread, half of which is placed inside the needle, whereas the other half is outside and fixed by the holder. The conductor needle is injected under the skin parallel to its surface. Results. We found that dermal implantation of monofilament polydioxanone threads did not cause pronounced exudative inflammation, allergic reactions (complete absence of eosinophils in the infiltrate), or pronounced fibrosis of the stroma with the growth of rough cicatricial connective tissue (only thin layers of collagen around the threads). The inflammatory infiltrate around the threads contained foci of mild productive inflammation; the area of inflammatory infiltration decreased with time. Immunohistochemical staining of tissues for CD31 demonstrated that thread implantation stimulated growth of the fibrous component in the surrounding connective tissue, including the areas around the filaments, border areas, and overlying dermis of the skin. Conclusion. 1. Subdermal implantation of monofilament polydioxanone threads is safe, because it doesn’t lead to necrosis, dystrophic changes of surrounding tissues, paretic changes, vascular thrombosis, dystrophic changes of nerve fibers, and destructive changes of skin appendages. 2. Subdermal implantation of monofilament polydioxanone threads effectively stimulates growth of the fibrous component in the surrounding connective tissue. 3. Subdermal implantation of monofilament polydioxanone threads stimulates neovascularization in the surrounding subcutaneous tissue and overlying dermis of the skin.