Comparison of the effects of fractional microneedle radiofrequency and microneedling on modulating the senescent fibroblast milieu in aged skin

Skin ageing is a complex and multifaceted biological process that involves the accumulation of senescent dermal fibroblasts. While fractional microneedle radiofrequency (MNRF) is widely used for skin rejuvenation, the underlying molecular mechanisms are unknown. This study aimed to investigate the efficacy of fractional MNRF in altering the cellular milieu of aged skin and to evaluate clinical skin improvements. Thirty female volunteers aged ≥ 60 years with visible periorbital wrinkles received four consecutive treatments of either microneedling or MNRF on randomly assigned facial sides. Based on biophysical measurements, MNRF treatment improved wrinkles, elasticity, hydration, and transepidermal water loss compared to baseline. Histological analysis revealed that the MNRF-treated sides exhibited increased proliferation of non-senescent fibroblasts, a reduced number of senescent fibroblasts, and elevated collagen and elastin levels, compared to the MN-treated sides. In additional analyses, differences in collagen density and hydration between the two sides of the face were statistically significant only in subjects with a marked reduction in senescent fibroblasts in MNRF-treated sides. Our data suggest that, compared to MN, MNRF induces greater clinical and histological improvements in aged skin, likely by altering the dermal fibroblast milieu through the dual effect of eliminating senescent fibroblasts and increasing the number of non-senescent fibroblasts.