Hyaluronic Acid-Based Nanohydrogel as Effective Carrier for Transdermal Delivery of CBD for Melanoma Cancer Therapy

<p dir="ltr">Significance of this research: Cutaneous melanoma, located at the junction of the epidermis and dermis, is a prevalent form of skin cancer. Transcutaneous drug delivery offers a promising approach to directly target melanoma cells without the need for undergoing gastrointestinal or liver metabolism. Cannabidiol (CBD) has shown potential as an anti-tumour or anti-cancer agent, either alone or in combination therapy for melanoma. However, improvements are needed in CBD’s bioavailability, stability, efficacy, and sustained delivery. A comprehensive literature review identified a significant research gap in the nano-encapsulation of CBD and its transdermal delivery for melanoma treatment. </p><p dir="ltr">Methodology: The methodology involved the chemical modification of hyaluronic acid (HA) through grafting a fatty amine (FA) onto its structure. The resulting HA conjugates (MH) with varying degrees of substitution were utilised to nano-encapsulate CBD using the high-energy nano-emulsification method. The properties of the optimised formulation, i.e. size, polydispersity, short- and long-term stability, loading efficiency, and release behaviour, were characterised. The limited in vitro toxicity of the empty nano-formulation and the anti-proliferative, apoptotic-inducing, and migration inhibition abilities of the CBD-loaded nano-formulation were assessed using malignant melanoma cell lines and normal human cell lines. Cellular and subcellular trafficking of the labelled nano-formulation were tracked and quantified by confocal microscopy and flow cytometry techniques. Furthermore, an ex vivo permeation protocol using pig ear skin was utilised to evaluate CBD release and penetration through the skin. </p><p dir="ltr">Results: The results demonstrated successful conjugation of FA in the HA structure, leading to the development of a carrier that preserved CBD in the oil core and exhibited excellent long-term stability at ambient temperature. The nano-formulation displayed controlled release profiles at physiological and acidic pH, with a stable droplet size (~75 nm) and low polydispersity. The empty nano-formulation exhibited high biocompatibility with both malignant melanoma and normal cell lines. In contrast, the nano-encapsulated CBD demonstrated selective cytotoxicity and apoptotic induction in cancerous cell lines compared to normal cells in 2D and 3D cultures. Moreover, the nano-formulation, with or without CBD, showed penetration beyond the stratum corneum into the deeper layers of the viable epidermis where melanocytes originate. </p><p dir="ltr">Conclusion: The current project successfully developed a facile and mild method for encapsulating CBD, resulting in nano-carriers with demonstrated efficiency in inhibiting the proliferation of primary and secondary melanoma cancer cell lines. The optimised nano-carriers exhibited a sustained release pattern over a 72-hour period under in vitro conditions. Additionally, these nano-carriers demonstrated pH sensitivity, allowing CBD to detach from the nano-carrier at the target tissue and potentially maintain therapeutic release within the desired range. The outcomes of this research hold promise for introducing a new transdermal nano-carrier that can enhance the efficiency of CBD in treating melanoma cancer, increase skin permeability, and improve CBD’s stability. </p><p dir="ltr">Key unique aspects: Here are a few key unique aspects: </p><p dir="ltr">• Technical advantages of optimised formulation include excellent long-term stability at ambient temperature, controlled release profiles at physiological and acidic pH, selective cytotoxicity, a stable droplet size with low polydispersity, and enhanced delivery to deeper layers of the skin. These properties could potentially enhance the therapeutic efficacy of CBD. </p><p dir="ltr">• Selective Cytotoxicity: The nano-encapsulated CBD demonstrated selective cytotoxicity and apoptotic induction in cancerous cell lines compared to normal cells in 2D and 3D cultures. This selective cytotoxicity is crucial to cancer therapy, as it can potentially minimise damage to healthy cells. </p><p dir="ltr">• Transdermal Delivery: The nano-formulation, with or without CBD, showed penetration beyond the stratum corneum into the deeper layers of the viable epidermis where melanocytes originate. This suggests that our optimised nano-formulation could potentially be used for transdermal delivery of CBD or similar therapeutic molecules, which could be a less invasive and more convenient method of administration for patients.</p>