Efficacy study of the new polycaprolactone thread compared with other commercialized threads in a murine model

BACKGROUND: Polydioxanone (PDO) threads, poly‐L‐lactic acid (PLLA) threads, and polycaprolactone (PCL) threads have been used for lifting and antiaging purposes. The new PCL threads that have less residual monomer compared to the previous PCL are developed. AIMS: The efficacy of threads regarding collagen synthesis and wrinkle improvement was evaluated in vivo model. METHODS: In this study, threads were inserted into 30 six‐week‐old male SKH‐1 hairless mice. One of four threads was implanted at either side of the spine of each mouse. Biopsy specimens obtained at 1, 4, and 8 weeks were examined using hematoxylin and eosin (H&E) and Herovici's stain. Additionally, immunoblot analysis was performed using primary antibody for collagen type III and transforming growth factor‐β (TGF‐β) and visualized by chemiluminescence and densitometric quantification. Finally, skin replicas were used to calculate total wrinkle area (mm(2)). RESULTS: Neocollagenesis was significantly increased by 50% in the new PCL and pre‐existing PCL groups at 8 weeks (p value < 0.001). Additionally, new‐PCL‐implanted mice showed a significant increase in collagen type III and TGF‐β expressions at 8 weeks (p value < 0.001). The number of inflammatory cells was also increased in the skin of PCL‐implanted mice at 8 weeks. Finally, wrinkles were reduced about 20% in the new PCL group at 8 weeks. CONCLUSIONS: The new PCL thread exhibited a superior skin rejuvenation effect. This suggests that the material processing technology can be applied not only to the thread but also to various products such as dermal filler and cosmetics.