Skin penetration of ultradeformable liposomes for topical drug delivery: CLSM as a tool of analysis

M. NATALIA CALIENNI; SILVIA ALONSO; JORGE MONTANARI

La Plata

Workshop; Imaging Techniques for Biotechnology and Biomedical Applications ? Workshop; 2016

Ultradeformable liposomes (UL) of soy phosphatidylcholine and sodium cholate are a type of drug delivery nanosystem (Montanari et al. 2007). UL are capable to penetrate the stratum corneum of the skin impelled by the dehydration pressure caused by the transdermal humidity gradient (Cevc and Blume, 1992). The incorporation of drugs in UL improves specific-site delivery and aims to reduce collateral effects (Betancourt, et al., 2009). Therefore, it is crucial to determine if the novel formulations continue to penetrate the stratum corneum and release their content into the viable epidermis.UL loaded with the antitumoral drug 5-Fluorouracil (5FU) and two fluorescent dyes: Fluorescein Isothiocyanate (aqueous core of UL) and 1,2 Dipalmitoyl-sn-glycero-3- phosphoethanolamine-N-(Lissamine? rhodamine B sulfonyl) (membrane of UL), were non-occlusively applied on human skin in a Saarbrücken Penetration Model device 1 hour at 37ºC. Human skin explants were obtained from abdominal surgery discards from caucasian 39 years old woman. After incubation, the full skin thickness was optically scanned at 6 μm increments through the z-axis by confocal laser scanning microscopy (CLSM) until 60 µm profundity. Also, histological slides of incubated skin obtained by cryosectioning were studied by CLSM (Montanari, et al. 2010). Fluorescence intensity of each image was obtained by Image-J software. The same histological slides were also subjected to hematoxylin and eosin staining in order to detect the possible presence of histological alterations in the analyzed tissues, using light microscopy. 5FU-loaded conventional liposomes (without the border activator sodium cholate) were used as control of non-penetrant formulation. 5FU delivery was indirectly observed both in the stratum corneum and in the viable epidermis. The dyes have penetrated together along the skin explant as it was evidenced with the CLSM analysis. However, in the histological slides, the lipophilic dye intensity was higher in the stratum corneum whereas the hydrophilic dye intensity was higher in the viable epidermis. Therefore, the formulation conserves its key feature of skin penetration at body temperature after encapsulation of 5FU.ReferencesBetancourt, T., et al., Controlled release and nanotechnology, in Nanotechnology in Drug Delivery, 2009, Springer. p. 283-312.Cevc, G. and G. Blume, Lipid vesicles penetrate into intact skin owing to the transdermal osmotic gradients and hydration force. Biochim Biophys Acta, 1992. 1104(1): p. 226-32.Montanari, J., et al., Photodynamic ultradeformable liposomes: Design and characterization. Int J Pharm, 2007. 330(1-2): p. 183-94.Montanari, J., et al., Sunlight triggered photodynamic ultradeformable liposomes against Leishmania braziliensis are also leishmanicidal in the dark. J Control Release, 2010. 147(3): p. 368-76.