HISTOLOGICAL EXAMINATION OF THE IMPLANTATION AREA OF LIFTING THREADS BASED ON POLY-L-LACTIC ACID (PLA) COATED WITH HYALURONIC ACID (HA) IN A LONG-TERM EXPERIMENT (1 YEAR)

Abstract

Background. In cosmetology clinics, combinations of techniques are used, so quite often thread lifting is combined with hyaluronic acid injections. In this regard, in order to increase the efficiency and simplify the thread lifting procedure, Aptos developed yarns from a copolymer of L-lactide with ε-caprolactone (poly-L-lactic acid) coated with hyaluronic acid. The purpose of the study: comparison in a long experiment of the effectiveness of the use of filaments based on PLA and PLA HA. Materials and methods. An experimental study was conducted on a pig 4 months., weight 40 kg. 5 threads were implanted on each side of the animal. The operation went without complications. After installation of the threads, skin with subcutaneous fatty tissue was taken for histological examination at the following implantation periods: 14 days, 30 days, 60 days, 90 days, 1 year. Tissue fragments were fixed in neutral 10% formalin; standard histological processing was performed. Sections were stained with: hematoxylin – eosin; according to the Weigert- Van Gieson method; Sirius Red coloring. Micrographs included: an assessment of the inflammatory response, an assessment of the cellular composition, an assessment of collagen and elastic fibers, the identification of the percentage of collagen types, the thickness of the implanted threads. Results. When comparing PLA and PLA HA materials, we can conclude that the latter has a more favorable effect on the skin and subcutaneous fat. The PLA HA material stimulated the formation of elastic fibers largely, especially intensively: in the subcutaneous fatty tissue during the first 2 months; in the skin starting from half of the first month to 3 months. In addition, PLA HA material had a higher percentage of type I and type III collagen at all withdrawal periods. When using this material, collagen fibers were produced at an earlier date and in larger quantities. Conclusions. Based on histological examination, the effectiveness of the use of lifting threads coated with hyaluronic acid has been proved. Moreover, hyaluronic acid did not have any effect on the filament from PLA. The dynamics of the thickness of the thread without HA and with HA was completely repeated.

Keywords

• skin aging
• thread lifting
• poly-l-lactic acid
• hyaluronic acid
• neocollagenesis