Ablative Fractional Lasers Versus Needle-Based Devices for Poly- l -Lactic Acid Delivery: An Optical Coherence Tomography and Histology Study.

Abstract

Background: Poly- l -lactic acid (PLLA) is widely used in dermatology, traditionally through subcutaneous injections. Alternative delivery methods such as ablative fractional lasers (AFLs) and needle-based devices have gained interest, but limited data exist on their efficacy.

Objective: To assess the effectiveness of AFLs and needle-based devices for PLLA delivery and the impact of channel morphology on PLLA uptake.

Methods: Full-thickness human abdominal skin samples were treated with fractional CO 2 laser, fractional difference frequency generation (DFG) laser, fractional microneedle radiofrequency (MNRF), and microneedle (MN). After applying PLLA topically, real-time particle movement into the channels was detected through optical coherence tomography (OCT). Histology assessed the vertical distribution of PLLA.

Results: Optical coherence tomography captured PLLA particles descending into channels from AFLs, but not MNRF or MN. Histology confirmed PLLA uptake in up to 80.3% of CO 2 channels and 61.9% of DFG channels, compared with minimal uptake with MNRF (1.4%) and MN (0.7%). The CO 2 laser enabled deeper penetration (120-240 μm), whereas the DFG laser delivered more superficially (0-120 μm).

Conclusion: Ablative fractional lasers effectively delivered PLLA through the skin, while needle-based devices showed minimal uptake. Among AFLs, channel geometry influenced vertical particle distribution. In vivo and clinical studies are needed to assess PLLA retention and its impact on remodeling.