Time and depth resolved visualisation of the diffusion of a lipophilic dye into the hair follicle of fresh unfixed human scalp skin.
Visualising the penetration pathway of a lipophilic model dye into the hair follicle of fresh unfixed human skin would facilitate optimisation of drug formulations for local delivery to the pilosebaceous unit. A block of fresh human scalp skin was mechanically fixed in a newly designed combination of cutting device/on-line diffusion cell, manual cross-sectioned perpendicular to the skin surface and sealed to create the donor and acceptor compartment. The donor phase consisted of a saturated solution of Bodipy FL C(5) in a citric acid buffer solution. Images were obtained on-line by confocal laser scanning microscopy (CLSM) every 30 min for 16 h. For each time point and each skin region relative intensity values were calculated. The on-line visualisation showed a fast diffusion of the label into the gap of the hair follicle followed by a fluorescent staining in the gap itself. The data strongly indicate that the fluorescence in the cuticle originates mainly from the dye of the gap and not from the surrounding epidermis. The on-line visualisation provides a new and excellent tool to monitor simultaneous changes in distribution profiles in the various skin layers including the hair follicle. This information can be used to determine penetration pathways in the skin.
Grams
Ylva Y
YY
Leiden/Amsterdam Centre for Drug Research, Department of Pharmaceutical Technology, Leiden University, P.O. Box 9502, Einsteinweg 55, 2300 RA Leiden, The Netherlands.
Whitehead
Lynne
L
Cornwell
Paul
P
Bouwstra
Joke A
JA
D000368:Aged; D000465:Algorithms; D004058:Diffusion; D015194:Diffusion Chambers, Culture; D005260:Female; D006202:Hair Dyes / Q000493:pharmacokinetics*; D018859:Hair Follicle / Q000033:anatomy & histology / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D066298:In Vitro Techniques; D008297:Male; D008856:Microscopy, Fluorescence; D008875:Middle Aged; D012535:Scalp; D012869:Skin Absorption / Q000502:physiology*
D006202:Hair Dyes