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

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. 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. 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. 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.