The clinical effects and skin histological changes induced by a novel insulated radiofrequency microneedle: a pilot study.

Radiofrequency microneedle (RFMN) could mechanically penetrates the epidermis and emits radiofrequency energy to the target skin layer. This innovative system offers the capability to deliver precisely controlled radiofrequency energy at varying depths within the skin in a single insertion. We hypothesized that the new RFMN could improve both pore size and skin laxity simultaneously by single insertion and multiple discharges, thus reducing the number of treatment passes and improving the treatment efficiency. Therefore, we carried out this pilot study to confirm the clinical effects and corresponding histological changes. In clinical part, 3 subjects received a single RFMN treatment. Subjects' faces were randomly divided into superficial base-energy and deep high-energy side or superficial high-energy and deep base-energy side. Facial characteristics were documented using standardized photographic techniques at various points in the study. In animal experiment, the abdomen of Bama miniature pig was divided into 4 treatment zones: the blank control group; superficial base-energy and deep high-energy group; superficial high-energy and deep base-energy group; no energy control group. Skin samples were collected immediately and 1 month post-treatment for histological analysis to observe the corresponding histological changes. Immediately after treatment, we found that the severity of erythema and petechiae may be related to the parameter settings. 1 month after treatment, improvement in skin laxity and facial pore size on both sides of the face was observed. The treatment resulted in a more significant improvement in relaxation on the superficial base-energy and deep high-energy side, but the pore improvement appeared to be more pronounced on the superficial high-energy and deep base-energy side. A trend of decreasing intensity in vascular dilatation was observed across the treatment groups, with the superficial high-energy and deep base-energy group exhibiting the most pronounced dilation. Histological observations immediately after treatment revealed that 2 seperated injury zones, which was caused by the same needle discharged electric twice, and one charge in the deep and one in the shallow. Immediate post-treatment dilation of blood vessels in all treatment groups was observed. A trend of decreasing intensity in vascular dilatation was observed across the treatment groups, with the superficial high-energy and deep base-energy group exhibiting the most pronounced dilation. 1 month post-treatment, histological analysis revealed an increase in dermal thickness, elastin, collagen fiber thickness and density, perivascular inflammatory cell infiltration across all treatment groups. Overall, our study demonstrated that variations in energy delivered at different depths by a new RFMN could induce distinct histological changes and corresponding clinical efficacy. This finding holds promise for optimizing the clinical application of RFMN. By tailoring the depth and energy settings in one insertion, specific concerns such as enlarged pores or facial laxity can be addressed more efficiently.