Rapamycin and HPPH Co-Loaded Nanodrug Delivered via Dissolvable Microneedles to Treat Port-Wine Stains

Objective Port-wine stains are a kind of dermatological disease of congenital capillary malformation. Based on the biological characteristics of port-wine stains and the advantages of microneedle transdermal administration, we intend to construct a nanodrug co-loaded with rapamycin (RPM), an anti-angiogenesis drug, and photochlor (HPPH), a photosensitizer, and integrate the nanodrug with dissolvable microneedles (MN) to achieve anti-angiogenesis and photodynamic combination therapy for port-wine stains.

Methods  First, RPM and HPPH co-loaded nanoparticles (RPM-HPPH NP) were prepared by the emulsification solvent-volatilization method, and its ability to generate reactive oxygen species (ROS) was investigated under 660 nm laser irradiation. Mouse hemangioendothelioma endothelial cells (EOMA) were used as the subjects of the study. The cellular uptake behaviors were examined by fluorescence microscopy and flow cytometry. The cytotoxicity effects of RPM-HPPH NP with or without 660 nm laser irradiation on EOMA cells were examined by MTT assays (with free RPM serving as the control). Then, hyaluronic acid (HA) dissolvable microneedles loaded with RPM-HPPH NP (RPM-HPPH NP@HA MN) were obtained by compounding the nanodrug with HA dissolvable microneedle system through the molding method. The morphological characteristics and mechanical properties of RPM-HPPH NP@HA MN were investigated by scanning electron microscope and electronic universal testing machine. The penetration ability of RPM-HPPH NP@HA MN on the skin of nude mice was evaluated by trypan blue staining and H&E staining experiment.

Results The RPM-HPPH NP prepared in the study had a particle size of 150 nm and generated large amounts of ROS under laser irradiation. At the cellular level, RPM-HPPH NP was taken up by EOMA cells in a time-dependent manner. The cytotoxicity of RPM-HPPH NP was higher than that of free RPM with or without laser irradiation. Under laser irradiation, RPM-HPPH NP exhibited stronger cytotoxic effects and the difference was statistically significant (P<0.05). The height of the needle tip of RPM-HPPH NP@HA MN was 600 µm and the mechanical property of a single needle was 0.75048 N. Trypan blue staining and HE staining showed that pressing on the microneedles could produce pores on the skin surface and penetration of the stratum corneum.

Conclusion RPM-HPPH NP@HA MN can deliver RPM-HPPH NP percutaneously to the lesion tissue and realize the synergistic treatment of port-wine stains with anti-angiogenic therapy and photodynamic therapy, providing a new strategy for the construction of nanodrug-loaded microneedle delivery system and the clinical treatment of port-wine stains.