Enhancing dermal collagen density towards youthfulness: A comparative study of PCL, PLLA, and PDO thread implantation in aging rats model.

Objectives: Both intrinsic and extrinsic factors cause skin aging. Intrinsic aging is characterized by decreased collagen density, particularly collagen types I (COL1A1) and III (COL3A1), and an increase in the COL1/COL3 ratio. Extrinsic aging, primarily due to ultraviolet light exposure, leads to photoaging, which causes collagen fragmentation and reduced production, leading to skin sagging. Thread lifts, a nonsurgical method, aim to tighten the skin and stimulate collagen production using biodegradable monofilament threads such as polydioxanone (PDO), poly-lactic acid (PLLA), and polycaprolactone (PCL). This study compared the effectiveness of PDO, PLLA, and PCL threads in reversing aging by enhancing dermal collagen, reducing the COL1/COL3 ratio, and increasing COL3A1 gene expression in UVB-exposed aging model rats.

Materials and methods: Thirty female Wistar (Rattus norvegicus) rats were divided into six groups, and their back hair was shaved and exposed to 840 mJ/m² UVB for 4 weeks. Skin biopsy specimens were assessed using Sirius Red staining to determine dermal collagen density and the COL1/COL3 ratio. Furthermore, qRT-PCR was used to examine COL3A1 gene expression.

Results: PDO, PLLA, and PCL threads enhanced skin quality, similar to the young negative control group, based on parameters such as dermal collagen density, COL1/COL3 ratio, and COL3A1 gene expression. PCL thread was more active than PDO and PLLA.

Conclusion: Thread implantation may result in a more youthful collagen profile than negative control and may be used to support skin anti-aging. The most effective thread was PCL compared to PDO and PLLA.