Polymeric Nanoparticles' Accumulation in Atopic Dermatitis: Clinical Comparison between Healthy, Non-Lesional, and Lesional Skin.

A major limitation in the current topical treatment strategies for inflammatory skin disorders is the inability to selectively target the inflamed site with minimal exposure of healthy skin. Atopic dermatitis is one of the most prevalent types of dermatitis. The use of polymeric nanoparticles for targeting inflamed skin has been recently proposed, and therefore the aim of this proof-of-concept clinical study was to investigate the skin penetration and deposition of polymeric biodegradable nanoparticles in the atopic dermatitis lesions and compare the data obtained to the deposition of the particles into the healthy skin or lesion-free skin of the atopic dermatitis patients. For that, fluorescent PLGA nanoparticles in sizes of approximately 100 nm were prepared and applied to the skin of healthy volunteers and the lesional and non-lesional skin of atopic dermatitis patients. Skin biopsies were examined using confocal laser scanning microscopy to track the skin deposition and depth of penetration of the particles. Immunohistochemistry was performed to investigate the alteration in tight-junction protein distribution in the different types of skin. Results have shown that nanoparticles were found to have higher deposition into the atopic dermatitis lesions with minimal accumulation in healthy or non-lesional skin. This has been primarily correlated with the impaired barrier properties of atopic dermatitis lesions with the reduced production of Claudin-1. It was concluded that polymeric nanoparticles offer a potential tool for selective drug delivery to inflamed skin with minimal exposure risk to healthy skin.

Size dependent skin penetration of nanoparticles in murine and porcine dermatitis models.

A major limitation in the current topical treatment of inflammatory skin diseases is the inability to selectively deliver the drug to the inflammation site. Recently, smart drug delivery systems such as nanocarriers are being investigated to enhance the selective deposition of anti-inflammatory drugs in inflamed areas of the skin to achieve higher therapeutic efficacy with minimal side effects. Of such systems, polymeric nanoparticles are considered very efficient carriers for the topical drug delivery. In the current work, poly(l-lactide-co-glycolide) nanoparticles of nominal sizes of 70nm (NP70) and 300nm (NP300) were studied for their intra-epidermal distribution in murine and pig atopic dermatitis models over time against the respective healthy controls. Confocal laser scanning microscopical examination of skin biopsies was utilized for the qualitative and semi-quantitative analyses of nanoparticles skin deposition and penetration depth. While no skin penetration was found for any of the particles in healthy skin, the accumulation of NP70 was significantly higher than NP300 in inflamed skin (15-fold in mice, 5-fold in pigs). Penetration depth of NP70 decreased over time in mice from 55±3µm to 20±2µm and similar tendencies were observed for the other formulations. In inflamed pig skin, a similar trend was found for the penetration depth (NP70: 46±12µm versus NP300: 23±3µm); however, the NP amount remained constant for the whole analyzed period. Their ability to penetrate specifically into inflamed skin combined with minimal effects on healthy skin underlines small polymeric nanoparticles' potential as selective drug carriers in future treatment of chronic inflammatory skin diseases such as atopic dermatitis.

Nanomedicine strategies for targeting skin inflammation.

Topical treatment of skin diseases is an attractive strategy as it receives high acceptance from patients, resulting in higher compliance and therapeutic outcomes. Recently, the use of variable nanocarriers for dermal application has been widely explored, as they offer several advantages compared with conventional topical preparations, including higher skin penetration, controlled and targeted drug delivery and the achievement of higher therapeutic effects. This article will focus on skin inflammation or dermatitis as it is one of the most common skin problems, describing the different types and causes of dermatitis, as well as the typical treatment regimens. The potential use of nanocarriers for targeting skin inflammation and the achievement of higher therapeutic effects using nanotechnology will be explored.