Enhancement of Fat Septa: Polycaprolactone (PCL) Microspheres Boost Collagen Production in Subcutaneous Adipose Tissue

The reduction in collagen content within the subcutaneous fat layer due to aging results in thinning and weakening of the fibrous septum, leading to an unstable fat pad. Studies on the mechanism of action of polycaprolactone (PCL) collagen stimulators in the adipose layer are lacking. This research aimed to explore the effectiveness of PCL-based filler in enhancing the fibrous septum within adipose tissue, thereby facilitating collagen and elastin synthesis in the adipose layer, while also comparing the disparities in the process between juvenile and aged individuals. A rat model was utilized to study subcutaneous fat implantation effects of PCL-based filler. Over 4 months, the impact on fibrous septum formation was evaluated with Masson's trichrome staining and immunostainings for Types I and III collagen, and a structural evaluation through scanning electron microscopy analysis. PCL-induced collagenization mechanisms were explored by quantitative polymerase chain reaction (qPCR). Elastin regeneration was examined with Elastica van Gieson (EVG) staining. Histological analysis demonstrated that PCL-based filler effectively stimulated collagen fiber formation in subcutaneous adipose tissue in both juvenile and aged rats. Immunostainings indicated significant promotion of Types I and III collagen regeneration, primarily within the interstitial spaces among adipocytes, as well as its confirmation at the genetic level through qPCR analysis. EVG staining further unveiled the role of PCL in promoting elastin production while mitigating age-related decline. PCL-based filler enhanced fat septum regeneration and deposition, demonstrating a robust, age-independent response. These findings suggest PCL-based fillers as promising therapeutic agents for rejuvenating subcutaneous adipose tissue and enhancing skin volume and elasticity in cosmetic and reconstructive contexts.