Melanin-Based Nanoparticles for Lymph Node Tattooing: Experimental, Histopathological and Ultrastructural Study.

Area of Science:

• Biomaterials Science
• Nanotechnology
• Surgical Oncology

Background:

• Targeted Axillary Dissection (TAD) relies on sentinel lymph node (SLN) identification for breast cancer treatment.
• Current SLN tattooing methods using carbon-based colloids face limitations like inflammatory reactions and particle migration, leading to SLN mismatch.
• Developing stable and accurate SLN visualization agents is crucial for effective TAD.

Purpose of the Study:

• To investigate melanin-loaded polymeric nanoparticles (Mel-NPs) as a novel endogenous pigment for SLN tattooing.
• To evaluate the identification rates, stability, and biological behavior of Mel-NPs in lymph node tissue.
• To overcome the limitations associated with traditional carbon-based SLN staining agents.

Main Methods:

• Synthesis and characterization of melanin-loaded polymeric nanoparticles (Mel-NPs).
• Tattooing of lymph nodes in pig models to assess Mel-NP performance.
• Histological and ultrastructural studies to analyze inflammatory responses and cellular uptake of Mel-NPs.

Main Results:

• Mel-NPs demonstrated high identification rates of tattooed lymph nodes, reaching 83.3% at 16 weeks post-tattooing.
• No significant reduction in identification was observed over time, indicating colloid stability within lymph node tissue.
• Histological analysis revealed foreign-body-like granulomatous inflammation and macrophage uptake with associated cellular damage.

Conclusions:

• Melanin nanoparticles (Mel-NPs) represent a viable and stable alternative for SLN tattooing in the context of TAD.
• While Mel-NPs show promise, their associated inflammatory responses and macrophage interactions require further investigation.
• Further research is warranted to optimize Mel-NP formulations for improved biocompatibility and efficacy in breast cancer surgery.