Efficacy of Lifting Threads Composed of Poly(L-Lactide-Co-ε-Caprolactone) Copolymers Coated With Hyaluronic Acid: A Long-Term Study on Biorevitalizing Properties in Skin Remodeling

Background

Facial thread lifting, which is popular in aesthetic medicine because of its minimal invasiveness, has led to advancements in the use of biodegradable polymers such as poly(L-lactide-co-ε-caprolactone) (P(LA/CL)) and its hyaluronic acid-coated variant (P(LA/CL)-HA). These developments enhance biocompatibility and efficacy, offering prolonged benefits through better biostimulation and tissue integration.

Methods

A controlled experiment involving five 4-month-old female pigs compared the effectiveness of P(LA/CL) and P(LA/CL)-HA threads over six months. After being implanted into the subcutaneous layer parallel to the skin of each pig, the threads were evaluated through histological analysis at intervals (7, 21, 30, 90, and 180 days) to assess changes in dermal and hypodermal structures, collagen types, elastin levels, and tissue integration via stains such as hematoxylin and eosin (H&E), Weigert-Van Gieson, and Sirius Red.

Results

P(LA/CL) and P(LA/CL)-HA threads significantly led to dermal and hypodermal remodeling. By day 180, a comparative analysis via the Wilcoxon test revealed that P(LA/CL)-HA significantly outperformed P(LA/CL) in most histological indicators because of the biostimulatory effects of hyaluronic acid.

Conclusions

Our study investigated the effects of two types of bioabsorbable threads, P(LA/CL) and P(LA/CL)-HA, on skin remodeling over 180 days in a porcine model. These results highlight the significant role of thread composition in tissue remodeling and suggest that incorporating HA could optimize therapeutic and aesthetic outcomes. Further clinical research is necessary to confirm these findings in human subjects.