In Vitro Permeation of Nickel Salts Through Human Stratum Corneum

Abstract

Allergic contact dermatitis due to nickel salts is common. It isexperiments, thus making comparisons across studies diYcult therefore important to measure the permeation of these salts(1). through the stratum corneum (SC ), the primary rate-limitingAs a well-known irritant and allergen, nickel causes both domain in skin. An advanced diVusion system and analytical immediate and delayed, speci c and non-speci c type allergy techniques now enable better measurement of the ux than was reactions following dermal exposure (2-4). The dermatotoxicpossible in earlier experiments. Human SC was prepared by ology of nickel compounds presents a major scienti c challenge trypsinization of dermatomed cadaver leg skin. The diVusion owing to the apparent paradoxes observed in its behavior in system included diVusion cells with a spiral line. Aqueous contact with the epidermis, so several signi cant issues await solutions of nickel salts (Ni(NO 3 ) 2 , NiSO 4 , NiCl 2 and resolution reconciled through appropriate experimentation. To Ni(Õ OOCCH3 ) 2 at 1% Ni2+ concentration) were used as the date, the most comprehensive study of skin permeation by donor solution (400 lL / cell ). The receptor uid, pure water, inorganic nickel salts was performed in vitro on full-thickness was collected up to 96 h after application of the donor solutions.skin (5). The present study focuses only on the permeation of Nickel concentrations in the donor and receptor uid, as well as nickel from various salts across the uppermost layer of the in the SC, were analysed using inductively coupled plasma mass epidermis, the stratum corneum (SC ). With the aid of sophistspectrometry (ICP-MS) with a con dence limit of 0.5 ppb.icated analytical methods such as inductively coupled plasma Based on the total recovery of nickel from the experiments, mass spectroscopy (ICP-MS ) (6, 7), it is now possible to about 98% of the dose remained in the donor solution, whereas accurately detect ultra-trace amounts of the metal in biological 1% or less was retained in SC and less than 1% was found in substrates, such as SC tissue or the donor and receptor phases the receptor uid. Following an early surge, nickel permeates from in vitro studies, yielding a suYciently accurate picture of slowly across SC. The steady-state permeability coeYcients of metal adsorption and absorption. nickel were calculated from the ux data (approximately This investigation was designed to clarify the eVect the 5.2-8.5´10Õ 7 cm / h) with no signi cant diVerence among the counter ions sulfate, chloride, nitrate and acetate may have salts. The results concur in principle with earlier studies conon in vitro diVusion of aqueous nickel solutions applied at a ducted using the full-thickness human skin in vitro, and suggest 1% nickel concentration level. We measured respective steadythat in vivo nickel ions may permeate simultaneously by routes state ux values under the most conclusive experimental of diVusion such as the shunt pathway, apart from slow transcelconditions possible. Using human SC separated b...

Nickel Susceptibility and Skin Barrier Function to Water after Treatment with a Urea-Containing Moisturizer

“…Thus, for substances that penetrate the bulk stratum corneum very slowly, these shunt pathways can be signifi cant [57] . Experimentally it has also been shown that the highest rate of nickel penetration from different salt solution occurs primarily in the fi rst 24 h [54] and the low and variable penetration of nickel across isolated skin supports the view of the importance of transfollicular diffusion, although the intercellular avenue should not be neglected [58] . Patchy skin reactions after testing of nickel allergy are also compatible with high concentrations of nickel in the appendages, especially in the concentration range between defi nite positive and negative reactions [44,59,60] .…”

“…The bricksand-mortar array is considered an extremely effective barrier for nickel, making the role of the skin appendages a more likely route for absorption [54] . The skin is pierced by a variety of appendages that can allow an easier diffusion pathway in parallel to the normal route through the stratum corneum per se.…”

Flux of a Nickel(II) Salt versus a Nickel(II) Soap across Human Skin in vitro

“…While in earlier experiments conducted with SC less than 1% of the applied dose permeated the SC or was retained in that tissue [7], in the present experiment 35.7 B 0.2% of the chloride dose and 6.4 B 2.7% of the soap reached the receptor phase (n = 3). On the other hand, retention of the NiDO in the tissue was significantly higher than the amount of nickel dosed as the chloride, with 0.6% (3,550 B 310 ppb) versus 0.02% (90 B 30 ppm) of the dose, respectively (table 4).…”

“…It is also remarkable and indicative for the nature of the split-thickness barrier material used in this experiment that steady-state conditions were attained in the earliest stages of diffusion, whereas in the earlier experiment using SC steady state was observed only after 24 h, permeation continuing then for more than 96 h at a low flux [7]. Especially in the nickel chloride experiment, no lag time was observed preceding diffusion, while through SC the lag times measured with various nickel salts would reach up to 90 h preceding the appearance of the permeant in the receptor phase [14,15].…”

“…The few in vitro diffusion experiments conducted so far with Ni(II) salts on human skin in fact show low K p values in the order of 10 -7 to 10 -5 [7]. Such values do little to explain the apparent prompt penetration of the stratum corneum (SC) by nickel in vivo and the subsequent reaction with epidermal cells, specifically with lymphocytes or Langerhans cells, which results in immune recognition and subsequent skin reactions.…”