Influence of nanocrystal size on the in vivo absorption kinetics of caffeine after topical application

The absorption of topically applied substances is challenging due to the effective skin barrier. Encapsulation of substances into nanoparticles was expected to be promising to increase the bioavailability of topically applied products. Since nanoparticles cannot traverse the intact skin barrier, but penetrate into the hair follicles, they could be used to deliver substances via hair follicles, where the active is released and can translocate independently transfollicularly into the viable epidermis. In the present in vivo study, this effect was investigated for caffeine. Caffeine nanocrystals of two sizes, 206 nm and 694 nm, with equal amounts of caffeine were used to study caffeine serum concentration kinetics after topical application on 5 human volunteers. The study demonstrated that at early time points, the smaller nanocrystals were more effective in increasing the bioavailability of caffeine, whereas after 20 min, the serum concentration of caffeine was higher when caffeine was applied by larger nanocrystals. Caffeine was still detectable after 5 days. The area under the curve could be increased by 82% when the 694 nm nanocrystals were applied. Especially larger sized nanocrystals seem to be a promising type of nanoparticulate preparation to increase the bioavailability of topically applied drugs via the transfollicular penetration pathway.

A Dual Fluorescence-Spin Label Probe for Visualization and Quantification of Target Molecules in Tissue by Multiplexed FLIM-EPR Spectroscopy

Simultaneous visualization and concentration quantification of molecules in biological tissue is an important though challenging goal. The advantages of fluorescence lifetime imaging microscopy (FLIM) for visualization, and electron paramagnetic resonance (EPR) spectroscopy for quantification are complementary. Their combination in a multiplexed approach promises a successful but ambitious strategy because of spin label-mediated fluorescence quenching. Here, we solved this problem and present the molecular design of a dual label (DL) compound comprising a highly fluorescent dye together with an EPR spin probe, which also renders the fluorescence lifetime to be concentration sensitive. The DL can easily be coupled to the biomolecule of choice, enabling in vivo and in vitro applications. This novel approach paves the way for elegant studies ranging from fundamental biological investigations to preclinical drug research, as shown in proof-of-principle penetration experiments in human skin ex vivo.

Formulation of drug-loaded oligodepsipeptide particles with submicron size

The size of particulate carriers is key to their transport and distribution in biological systems, and needs to be tailored in the higher submicron range to enable follicular uptake for dermal treatment. Oligodepsipeptides are promising nanoparticulate carrier systems as they can be designed to exhibit enhanced interaction with drug molecules. Here, a fabrication scheme for drug-loaded submicron particles from oligo[3-(S)-sec-butylmorpholine-2,5-dione]diol (OBMD) is presented based on an emulsion solvent evaporation method with cosolvent, surfactant, and polymer concentration as variable process parameters. The particle size (300-950 nm) increased with lower surfactant concentration and higher oligomer concentration. The addition of acetone increased the particle size at low surfactant concentration. Particle size remained stable upon the encapsulation of models compounds dexamethasone (DXM) and Nile red (NR), having different physicochemical properties. DXM was released faster compared to NR due to its higher water solubility. Overall, the results indicated that both drug-loading and size control of OBMD submicron particles can be achieved. When applied on porcine ear skin samples, the NR-loaded particles have been shown to allow NR penetration into the hair follicle and the depth reached with the 300 nm particles was comparable to the one reached with the cream formulation. A potential benefit of the particles compared to a cream is their sustained release profile.

Analysis of the morphometric parameters of pig ear hair follicles

BACKGROUND

Porcine ear skin is used in studies of percutaneous penetration as a substitute for human skin. The objective of the present study was to determine the structure of the hair follicles on the dorsal area of porcine ear skin and make a morphometric comparison with the hair follicles of human skin.

MATERIALS AND METHODS

Sections of frozen biopsies were cut vertically to the skin surface in longitudinal sections using a cryotome and were investigated using microscopy. For each hair follicle, various parameters were determined.

RESULTS

The follicular density in porcine ear skin varies according to the area studied, and the length of most of the follicles was approximately 1458 ± 286 μm. The size of the follicular orifice was also determined in a total of 305 follicles. It showed a diameter of roughly 113 ± 43 μm.

CONCLUSION

The results showed a very good similarity between human and pig hair follicles. Therefore, porcine ear skin can be considered as a very suitable model of human skin in dermal and especially follicular penetration studies.

Release of the model drug SR101 from polyurethane nanocapsules in porcine hair follicles triggered by LED-derived low dose UVA light

Hair follicles (HFs) are important drug delivery targets for the therapy of miscellaneous skin diseases and for skin antisepsis. Furthermore, HFs significantly contribute to drug delivery of topically applied substances. Nanoparticulate systems are excellently suited for follicular drug delivery as they entail the opportunity of directed drug transport into HFs. Moreover, they involve the possibility of an intrafollicular drug release initiated by extrinsic or intrinsic trigger mechanisms. In this study, we present a novel preclinical model for an anatomically and temporally targeted intrafollicular drug release. In vitro release kinetics of the model drug sulforhodamine 101 (SR101) from newly synthesized ultraviolet A (UVA)-responsive polyurethane nanocapsules (NCs) were investigated by fluorescence spectroscopy. Low power density UVA radiation provided by a UVA light emitting diode (LED) induced a drug release of over 50% after 2 min. We further utilized confocal laser scanning microscopy (CLSM) to investigate follicular penetration as well as intrafollicular drug release on an ex vivo porcine ear skin model. UVA-responsive degradation of the NCs at a mean follicular penetration depth of 509 ± 104 µm ensured liberation of SR101 in the right place and at the right time. Thus, for the first time a UVA-triggered drug release from NCs within HFs was demonstrated in the present study. Cytotoxicity tests revealed that NCs synthesized with isophorone diisocyanate show sufficient biocompatibility after UVA-induced cleavage. A considerable and controllable release of various water-soluble therapeutics could be reached by means of the presented system without risking any radiation-related tissue damage. Therefore, the implementation of the presented system into clinical routine, e.g. for preoperative antisepsis of HFs, appears very promising.

The impact of skin massage frequency on the intrafollicular transport of silica nanoparticles: Validation of the ratchet effect on an ex vivo porcine skin model

The human hair follicle (HF) represents a promising drug delivery target as an anatomical entity by itself, but also as a gateway enabling dermal or systemic bioavailability of active cosmetic and pharmaceutical ingredients. Due to its morphological characteristics, the HF provides a mechanically driven transport process of nanoparticles (NPs) when external forces are applied. This mechanism was presented as the so-called ratchet effect within the framework of an in silico study published recently. To investigate the influence of massage frequency on the penetration depth of NPs, and, by this, to validate the results obtained in silico, we implemented a corresponding application protocol on an ex vivo porcine skin model. In this connection, we compared three different skin massage frequencies (4.2 Hz, 50 Hz, 100 Hz) for the topical application of cyanine 5-labeled silica NPs (Cy5-SNPs). To elucidate the interplay of frequency and particle size, we furthermore applied Cy5-SNPs of three different diameters (300 nm, 676 nm, 1000 nm). Confocal laser scanning microscopy was utilized to investigate the follicular penetration depth of Cy5-SNPs on cryohistological slices. By this, we could demonstrate that the massage frequency and the follicular penetration depth exhibit an inverse relation pattern. Thus, the highest follicular penetration depth was observed within the 4.2 Hz group, while the lowest follicular penetration depth was found within the 100 Hz group for each Cy5-SNP size category. Additionally, we found that 676 nm Cy5-SNPs penetrated significantly deeper into HFs than 300 nm Cy5-SNPs and 1000 nm Cy5-SNPs, respectively. Summarizing, our results show that a low massage frequency including a dominant radial direction component leads to deeper follicular penetration depths of NPs than automated 3D-oscillation massage at 50 Hz or 100 Hz. Thus, our findings are in line with recent in silico results. Regarding translational purposes, our results are of high interest, since a massage executed at 250BPM (4.2 Hz) is within a realizable range for manual application, e.g. for the implementation into clinical routines or the domestic use of drugs or cosmetics. Furthermore, the application of different massage frequencies offers the opportunity of patho-specific targeting as different anatomical parts of the HF can be reached.

Investigation of transfollicular caffeine penetration using microdialysis on ex vivo porcine ear skin

The aim of this study was to develop an ex vivo method that allows to quantify the transfollicular penetration of topically applied substances by combining microdialysis and selective follicular closure with varnish. An experimental setup with three skin areas on ex vivo intact porcine ear skin was designed (varnish on hair follicle, varnish next to hair follicle, no varnish). On each area, 10 µl/cm² caffeine-hydroxyethyl-cellulose-gel was applied. Samples were collected for 22 h by microdialysis. After sampling, the skin layers were separated, homogenized and caffeine was quantified by high pressure liquid chromatography (HPLC) in all samples. Potential impact of the varnish placed next to the follicle by tension on the follicle during the drying process was monitored by a microscopic setup and could be excluded. The microdialysis and homogenization study showed a significantly reduced penetration of caffeine when the hair follicles were closed. In areas with open hair follicles caffeine was detected already in the first ten minutes after application. The reported novel combination of two methods is suitable to investigate ex vivo transfollicular penetration. Possible impact of the closure material in the control area can be ruled out by adjusting the design of the control area in future studies.

Application of parelectric spectroscopy to detect skin cancer-A pilot study

BACKGROUND

The early detection of skin cancer is still challenging and calls for objective, fast diagnostic, and ideally non-invasive methods in order to leave the potentially malignant tumor cells unaltered. In this paper, the parelectric spectroscopy was applied to evaluate the potential of a non-invasive detection of basal cell carcinoma (BCC) and malignant melanoma.

MATERIALS AND METHODS

A prototype of parelectric spectroscopy was used to investigate non-invasively dipole density and mobility of suspicious skin lesions. The differences in investigated tissue were analyzed compared to pathohistological findings in a clinical study on 51 patients with suspected BCC and malignant melanoma.

RESULTS

The non-invasive parelectric spectroscopy could differentiate between normal skin, BCC, and melanoma but failed to distinguish between different types of skin cancer. The data were normalized to unsuspected nearby skin because the different skin locations influence dipole density and mobility.

CONCLUSION

The results of the pilot study indicate that the parelectric spectroscopy might be an additional, useful non-invasive diagnostic procedure to distinguish between normal skin and skin cancer.

Solvent-Containing Closure Material Can Be Used to Prevent Follicular Penetration of Caffeine and Fluorescein Sodium Salt on Porcine Ear Skin

AIM

The skin represents a drug delivery portal. The establishment of a skin model capable of distinguishing between the follicular and intercellular penetration pathways remains a challenge. The study described herein was aimed at showing the influence of two nail varnishes as closure material and four application techniques to spread the active pharmaceutical ingredient (API) on a successful follicular closure without inducing penetration-enhancing effects.

MATERIALS AND METHODS

For all experiments, ex vivo porcine ear skin was used. In study design A, a standard and a solvent-free nail varnish were compared. It was tested whether the different application techniques (spreading with pipette, careful finger massage, 5-Hz finger massage, 5-Hz automatic massage) potentially destroy an intact follicular closure. Laser scanning microscopy imaging was used to measure if the model drug (fluorescein sodium salt) penetrated into the hair follicles. Study design B investigated how the penetration is affected when applying standard nail varnish containing solvents to skin. It was tested if the varnish blocks the API (caffeine) on completely covered areas and if adjacent areas show increased penetration. Furthermore, lateral diffusion of the API was investigated. After 20 h, the skin layers were separated by tape stripping and heat separation. The tissue samples were homogenized. Caffeine was quantified by chromatography.

RESULTS

In study design A, the standard nail varnish showed a secure follicular closure, while the solvent-free nail varnish was not able to prevent follicular penetration. Moreover, rapid application techniques were found to destroy an intact follicular closure. Only the two most gentle application techniques kept the follicular closing intact. In study design B, no caffeine was detected in both skin areas that were completely covered. Since no significant difference in caffeine penetration between the two uncovered groups was found, any influence of the applied closure material on adjacent areas was excluded.

CONCLUSION

This study clearly demonstrates that a standard nail varnish in combination with a gentle application technique of the API provides a secure follicular closure. The presented study only investigated the closure for the substances caffeine and fluorescein sodium salt. The results might not be transferable to all kinds of APIs.

Laser scanning microscopy for control of skin decontamination efficacy from airborne particulates using highly absorbent textile nanofiber material in combination with PEG-12 dimethicone

BACKGROUND

The decontamination of the skin is indispensable if airborne particulate contaminants deposit on the skin surface. Skin washing can have adverse effects as by skin rubbing the particles can be transferred deeply into the hair follicles, where they can be entrapped for a period of more than 10 days. Thus, alternative skin decontamination strategies are necessary.

MATERIALS AND METHODS

For imaging the contaminants in the skin, sodium fluorescein-labeled soot particles of submicron size (≈600 nm) were visualized using laser scanning microscopy.

RESULTS

In the present ex vivo pilot study on porcine ear skin, it was shown that sodium fluorescein-labeled soot particles of submicron size (≈600 nm) could be efficiently removed from the skin with highly absorbent textile nanofiber material, whose efficacy could be further increased by spraying the contaminated skin area with the viscous fluid PEG-12 dimethicone before textile application.

CONCLUSION

In case of skin contamination with particulates, the contact washing should be avoided due to rubbing particles deeply into the hair follicles, where they can accumulate for a long time and induce negative consequences. Efficient skin decontamination could include pretreatment of skin surface with the viscous fluid PEG-12 dimethicone and subsequent application of highly absorbent textile nanofiber material.

Recent advances in follicular drug delivery of nanoparticles

Introduction: The improvement of percutaneous absorption represents a clear dermatopharmaceutical aim. Recently, the hair follicle was recognized to be an important penetration pathway. Especially nanoparticles show an enhanced intrafollicular penetration and can be utilized to target specific cell populations within the hair follicle.Areas covered: The present review briefly summarizes the recent advances in follicular drug delivery of nanoparticles. Moreover, the particularities of the hair follicle as a penetration pathway are summarized which include its structure and specific barrier properties. Recently, the mechanism of the follicular penetration process has been clarified.In the meantime, different strategies have been developed to successfully improve follicular drug delivery of nanoparticles. One approach is to equip the nanocarriers with a triggered release system enabling them to release their drug load at the right time and place.Expert opinion: Follicular drug delivery with smart nanocarrier-based drug delivery systems represents a promising approach to increase the percutaneous absorption of topically applied substances. Although technical achievements and efficacy proofs concerning an increased penetration of substances are already available, the practical implementation into clinical application still represents an additional challenge and should be in the focus of interest in future research.

Barrier-disrupted skin: Quantitative analysis of tape and cyanoacrylate stripping efficiency by multiphoton tomography

Numerous studies have employed tape stripping (TS) or cyanoacrylate stripping (CS) to induce skin barrier disruption of the stratum corneum (SC) in human and porcine skin. However, the thickness of the remaining SC and the respective changes of the skin permeability have been rarely quantified. By using high-resolution multiphoton tomography, about 5 µm thick SC was found remaining on human skin after the performance of 30 times TS or 2 times CS. 50 tape strips or 4 times CS removed the entire human SC, but on porcine skin 2-3 µm thick SC was still left. TS can only reach the transition zone between the SC and the stratum granulosum because of the limited adhesion, whereas CS was able to remove viable skin layers. Permeation investigations on porcine skin revealed that the apparent permeability coefficient of the hydrophilic nitroxide spin 2,5,5-Tetramethyl-1-pyrrolidinyloxy-3-carboxylic acid increased 15-, 18-, and 21-fold when the SC amount remaining in the skin was 30%, 16%, and 8%, respectively. It is recommended to use at most 30 times TS or 3 times CS to obtain ex vivo barrier-disrupted skin that mimics diseased skin. The study provides quantitative information for the utility of TS and CS in skin penetration research.

Increasing the percutaneous absorption and follicular penetration of retinal by topical application of proretinal nanoparticles

Topical retinoids are frequently applied for therapeutic and cosmeceutical reasons although their bioavailability is low due to their chemical and photochemical instability. Moreover, skin irritation is a common side effect. Therefore, proretinal nanoparticles (PRN) as a novel formulation of topical retinoids, which are based on chitosan grafted with retinal through reversible linkage, were developed and their skin penetration behavior was studied. As nanoparticles preferably penetrate into the hair follicles, the follicular penetration depths of PRN at different time points were investigated. Moreover, the release capacity of the nanoparticulate system was studied using fluorescein as a model drug. Additionally, the concentration of retinal in the stratum corneum and in the hair follicles was quantified after application in particulate and non-particulate form. The results showed that the nanocarriers reached the infundibular area of the hair follicles, irrespective of the incubation time. The nanoparticles were able to release their model drug within the hair follicle. The retinal concentration delivered to the stratum corneum and the hair follicles was significantly higher when retinal was applied in the particulate form. In conclusion, the presented proretinal nanoparticle system may help to overcome the main problems of topical retinoid therapy, which are skin irritation, chemical and photochemical instability and low bioavailability, thus improving the topical retinoid therapy.

Influence of Storage and Preservation Techniques on Egg-Derived Carotenoids: A Substantial Source for Cutaneous Antioxidants

Antioxidants like carotenoids play a major role in the prevention of the destructive influence of free radicals in our skin. Carotenoids, as well as all other antioxidants, are substantial substances which must be supplied by nutrition. Resonance Raman spectroscopy (RRS) allows measurement of the carotenoid content of eggs, representing a rich carotenoid source in our nutrition. A previous study showed that eggs from organic production contain higher carotenoid levels in contrast to eggs from conventionally housed chicken. The uptake of these organically produced eggs led to an increased antioxidant concentration in the skin. In this study, the effects of different storage modalities, conservation techniques, and the effects of food processing on the carotenoid levels in eggs were investigated with RRS. Common storage modalities and preservation techniques showed only a limited influence on egg-derived carotenoid concentrations. However, a colder environment (at least for shell eggs) and high-pressure preservation had the best preservative influence on the carotenoid content. Surprisingly, food processing such as boiling increased the carotenoid concentration in eggs, whilst broiling destroyed the carotenoids almost completely. In conclusion, RRS is suitable for monitoring egg-derived carotenoid levels, and carotenoid levels in eggs are generally stable under common storage and preservation modalities. Boiling in contrast to broiling of eggs might be superior in terms of carotenoid preservation within food processing.

Temperature-Enhanced Follicular Penetration of Thermoresponsive Nanogels

Hair follicles can serve as an effective reservoir for dermal drug delivery upon the topical application of particulate substances. Here, the follicular penetration of an indodicarbocyanine-labelled thermoresponsive nanogel (189 nm) having a cloud point temperature of 34°C and linked via an acid-labile linker to the model drug indocarbocyanine was investigated. In total, 227 hair follicles of porcine ear skin were examined after topical application of the thermoresponsive nanogels at room temperature (21°C), physiological skin surface temperature (32°C) and core body temperature (37°C) for the follicular penetration depths of indodicarbocyanine and indocarbocyanine using confocal laser scanning microscopy. The results showed a significantly increased mean follicular penetration of the carrier to a depth of 298.8±85.8 μm after incubation at 37°C compared to samples incubated at 21°C and 32°C with mean follicular penetration depths of 202.7±81.7 μm and 219.4±52.9 μm, respectively (p<0.001). Possibly structural changes in the thermoresponsive nanogel induced by the increased incubation temperature led to an enhancement of follicular penetration. Therefore, thermoresponsive nanogels may be suitable for the temperature-enhanced penetration into the hair follicles under physiological conditions.

Hautkrebsprävention und Sonnenschutzcreme: ein Update

In den letzten Jahren sind die Hautkrebsraten weltweit gestiegen. Die Anwendung von Sonnenschutzmitteln ist eine weit verbreitete Strategie in der Prävention gegen Hautkrebs, Sonnenbrand und Photoalterung. Es sollten kombinierte Breitbandfiltersysteme mit hoher Wirkung gegen UV-B- und UV-A-Strahlung eingesetzt werden. Weitere Studien sind notwendig, um die Entwicklung von Sonnenschutzmitteln gegen die ebenfalls schädlichen IRA-Strahlen voranzutreiben. Obwohl die regelmäßige Anwendung von Sonnenschutzmitteln ein wesentlicher Bestandteil in der Hautkrebsprävention ist, sollten insbesondere bei Kindern kombinierte Schutzmaßnahmen angewendet werden: Sonnenkarenz bei starker Sonneneinstrahlung, textiler Sonnenschutz, Aufenthalt im Schatten und die Anwendung von Sonnenschutzmitteln.

Prevention of palmoplantar erythrodysesthesia in patients treated with pegylated liposomal doxorubicin (Caelyx®)

PURPOSE

Palmoplantar erythrodysesthesia (PPE) is one of the most frequent side effects during systemic treatment with pegylated liposomal doxorubicin (PLD, Caelyx®). PPE lesions show a range of symptoms, from numbness to painful erosions, and can have a major impact on the quality of life in affected patients. Previously, a possible pathomechanism of PPE was found in doxorubicin-treated patients based on radical formation in the skin. Here, a preventive strategy using a topically applied ointment with a high radical protection factor was investigated.

METHODS

In this randomized placebo-controlled double-blind study the antioxidant-containing ointment was compared with a placebo ointment regarding PPE grade III occurrence, overall PPE grade I-III occurrence and PPE severity in PLD patients. The verum or placebo cream was topically applied for a period of 16 weeks, starting 3 days prior to the first cycle of chemotherapy. Clinical evaluations were carried out by a dermatologist prior to the first cycle of chemotherapy and every 4 weeks for the duration of 16 weeks.

RESULTS

Thirty-two patients were enrolled in total, of which 17 (66%) completed the study. No PPE grade III was found in the verum group, while five out of seven patients (71%) had to be unblinded in the placebo arm due to PPE grade III (p = 0.003). General PPE occurrence of all grades was 60% under verum and 86% under placebo treatment.

CONCLUSIONS

The preventive application of an antioxidant-containing ointment was shown to be significantly more effective in the prevention of PPE grade III compared to placebo treatment.

Investigation of the cutaneous penetration behavior of dexamethasone loaded to nano-sized lipid particles by EPR spectroscopy, and confocal Raman and laser scanning microscopy

An improvement of the penetration efficiency combined with the controlled release of actives in the skin can facilitate the medical treatment of skin diseases immensely. Dexamethasone (Dx), a synthetic glucocorticoid, is frequently used for the treatment of inflammatory skin diseases. To investigate the penetration of nano-sized lipid particles (NLP) loaded with Dx in comparison to a commercially available base cream, different techniques were applied. Electron paramagnetic resonance (EPR) spectroscopy was used to monitor the penetration of Dx, which was covalently labeled with the spin probe 3-(Carboxy)-2,2,5,5-tetramethyl-1-pyrrolidinyloxy (PCA). The penetration into hair follicles was studied using confocal laser scanning microscopy (CLSM) with curcumin-loaded NLP. The penetration of the vehicle was followed by confocal Raman microscopy (CRM). Penetration studies using excised porcine skin revealed a more than twofold higher penetration efficiency for DxPCA into the stratum corneum (SC) after 24h incubation compared to 4h incubation when loaded to the NLP, whereas when applied in the base cream, almost no further penetration was observed beyond 4h. The distribution of DxPCA within the SC was investigated by consecutive tape stripping. The release of DxPCA from the base cream after 24h in deeper SC layers and the viable epidermis was shown by EPR. For NLP, no release from the carrier was observed, although DxPCA was detectable in the skin after the complete SC was removed. This phenomenon can be explained by the penetration of the NLP into the hair follicles. However, penetration profiles measured by CRM indicate that NLP did not penetrate as deeply into the SC as the base cream formulation. In conclusion, NLP can improve the accumulation of Dx in the skin and provide a reservoir within the SC and in the follicular infundibula.

Influence of Chemotherapy on the Antioxidant Status of Human Skin

BACKGROUND

Palmoplantar erythrodysesthesia is a frequent dermal side-effect during chemotherapy. Previous investigations showed radical formation subsequent to doxorubicin infusion and preventative and therapeutic effects of an antioxidant-containing ointment.

PATIENTS AND METHODS

Using a non-invasive vivomeasuring system (Biozoom®; Biozoom Services GmbH, Kassel, Germany) changes in the antioxidant status (as measured by relative carotenoid concentration) of the skin prior to and after intravenous administration of paclitaxel, docetaxel and 5-fluorouracil were investigated in 42 patients with cancer.

RESULTS

A significant decrease of antioxidant concentration subsequent to intravenous administration was found for all investigated chemotherapeutic agents. The mean concentration of carotenoids decreased from 3.59±1.26 arbitrary units (a.u.) to 3.41±1.28 a.u. (p<0.001) after paclitaxel administration, from 6.33±2.43 to 5.63±2.29 a.u. after docetaxel (p=0.027) and from 4.26±1.81 to 3.98±1.53 a.u. (p=0.042) after 5-fluorouracil infusion.

CONCLUSION

Oxidative stress might play a significant role in the pathomechanism of palmoplantar erythrodysesthesia associated with paclitaxel, docetaxel and 5-fluorouracil. Therefore, an antioxidant-containing ointment might serve as preventative and therapeutic option.

Penetration of topically applied nanocarriers into the hair follicles of dog and rat dorsal skin and porcine ear skin

BACKGROUND

In humans, topically applied nanocarriers penetrate effectively into the hair follicles where they can be exploited for the localized and targeted treatment of skin disorders.

OBJECTIVE

The objective of the present study was to examine the applicability of particle-based systems for follicular drug delivery in companion animals and livestock, which have a large follicular reservoir.

ANIMALS

Skin samples from 10 beagle dogs, 14 Wistar rats and four ears from freshly slaughtered cross-bred pigs were used.

METHODS

Fluoresceinamine labelled poly (L-lactide-co-glycolide) nanocarriers (256 or 430 nm) were applied on the different skin samples. After penetration, skin biopsies were removed and cryohistological cross sections prepared and investigated with regard to the follicular penetration depths (in μm ± standard deviation) of the nanocarriers using confocal laser scanning microscopy.

RESULTS

In canine, rat and porcine hair follicles, the smaller nanoparticles were detected at mean follicular penetration depths of 630.16 ± 135.75 μm, 253.55 ± 47.36 μm and 653.40 ± 94.71 μm, respectively. The larger particles were observed at average follicular depths of 604.79 ± 132.42 μm; 262.87 ± 55.25 μm and 786.81 ± 121.73 μm, respectively, in canine, rat and porcine hair follicles. Statistically significant differences (P < 0.05) in the mean follicular penetration depths of the differently sized nanocarriers could be determined for the canine and porcine skin samples.

CONCLUSION

The mean follicular penetration depths of the differently sized nanocarriers were mostly significantly different between the different species, which might be due to different species-specific follicular dimensions. This issue needs to be addressed specifically in further studies.

Detection of capecitabine (Xeloda®) on the skin surface after oral administration

Palmoplantar erythrodysesthesia (PPE), or hand-foot syndrome, is a cutaneous toxicity under various chemotherapeutics contributing to the most frequent side effects in patients treated with capecitabine (Xeloda®). The pathomechanism of PPE has been unclear. Here, the topical detection of capecitabine in the skin after oral application was shown in 10 patients receiving 2500  mg/m 2 /day 2500  mg/m2/day capecitabine. Sweat samples were taken prior to and one week after oral administration of capecitabine. Using high-resolution continuum source absorption spectrometry, the changes in concentrations of fluorine, which is an ingredient of capecitabine, were quantified and statistically analyzed. Here, we show an increase in fluorine concentrations from 40±10  ppb 40±10  ppb (2±0.5  pM 2±0.5  pM ) before capecitabine administration to 27.7±11.8  ppm 27.7±11.8  ppm (14.6±6.5  nM 14.6±6.5  nM ) after application, p<0.001 p<0.001 . The results show the secretion of capecitabine on the skin surface after oral administration, indicating a local toxic effect as a possible pathomechanism of PPE.

Prevention of Cutaneous Penetration and CD1c+ Uptake of Pollen Allergens by a Barrier-Enhancing Formulation

Recent studies have shown that pollen proteins can penetrate the impaired skin barrier of atopic patients and exacerbate their disease. In the presented study the effect of a topically applied barrier-enhancing formulation was investigated for its preventive effect on the uptake of pollen allergens into CD1c+ epidermal cells. The pollen proteins were fluorescence labelled and applied on barrier-disrupted excised human skin. CD1c+ cells were selected after magnetic cell sorting and analysed using laser scanning microscopy. In untreated disrupted skin, 81% of the CD1c+ cells contained the fluorescence-labelled pollen allergens. In formulation-pretreated skin only 12% of the CD1c+ cells showed an uptake of pollen allergens. These results encourage the treatment of atopic patients with barrier-enhancing formulations to reduce the impact of pollen on air-exposed skin areas and hence the exacerbation of cutaneous symptoms.

Significance of the follicular pathway for dermal substance penetration quantified by laser Doppler flowmetry

The understanding of transdermal substance penetration pathways remains an important field for the development of future topical drugs and cosmetics. Laser Doppler flowmetry is a well-established method for evaluating cutaneous perfusion. In a study on 6 healthy male volunteers, we topically applied the vasoactive substance benzyl nicotinate on two test areas with open and obturated hair follicles and measured changes in the blood flow by Doppler flowmetry. Contrary to occluded follicles, the application onto the test area with open follicles led to a statistically significant perfusion increase within the first 5 minutes, emphasizing the importance of the follicular pathway for epidermal penetration.

Relationship between Histological and Clinical Course of Psoriasis: A Pilot Investigation by Reflectance Confocal Microscopy during Goeckerman Treatment

Alterations of the skin microvasculature are known to play an important role in the development and maintenance of psoriatic skin lesions. In this study, we investigated lesional skin in 11 psoriatic patients during a modified Goeckerman treatment using reflectance confocal microscopy (RCM) to study the relationship between clinical clearance and histological normalization of psoriatic skin and the significance of histological abnormalities on the course of disease. The treatment regimen resulted in a significant reduction of the Psoriasis Area and Severity Index (PASI) as well as capillary and papillary diameters (p < 0.0001). The capillary and papillary diameters were still enlarged when compared to those in normal skin (p < 0.001). Capillary and papillary diameters correlated with each other prior to and after treatment (correlation coefficient = 0.63 and 0.64, p = 0.01 and 0.002, respectively) but not with the PASI. Capillary and papillary diameters after treatment and percentage reduction of the PASI during treatment seemed to be better predictors for the clinical course of relapse than the PASI after treatment. These findings make the subclinical changes of psoriatic skin vessels and dermal papillae a legitimate target for treatment. Further investigations of a large group of patients are needed to evaluate the potential of RCM findings as successor of the PASI in the monitoring of psoriasis.

Influence of Topical, Systemic and Combined Application of Antioxidants on the Barrier Properties of the Human Skin

BACKGROUND

The formation of free radicals in human skin by solar ultraviolet radiation is considered to be the main reason for extrinsic skin aging. The antioxidants in human tissue represent an efficient protection system against the destructive action of these reactive free radicals. In this study, the parameters of the skin, epidermal thickness, stratum corneum moisture, elasticity and wrinkle volume, were determined before and after the treatment with antioxidant- or placebo-containing tablets and creams.

METHODS

The study included 5 groups of 15 volunteers each, who were treated for 2 months with antioxidant-containing or placebo tablets, creams or a combination of antioxidant-containing tablets and cream. The skin parameters were measured at time point 0 and at week 8 utilizing ultrasound for the determination of epidermal thickness, a corneometer for stratum corneum moisture measurements, skin profilometry for quantifying the wrinkle volume and a cutometer for determining the elasticity.

RESULTS

The verum cream had a positive influence on epidermal thickness, elasticity and skin moisture, but the verum tablets improved the epidermal thickness only. The combined application of verum tablets and creams led to a significant improvement of all investigated skin parameters, whereas the application of placebo tablets or cream did not influence any parameters.

CONCLUSION

The topical and oral supplementation of antioxidants can be an instrument to improve several skin parameters and potentially counteract or decelerate the process of extrinsic skin aging.

Triggered release of model drug from AuNP-doped BSA nanocarriers in hair follicles using IRA radiation

Recent advances in the field of dermatotherapy have resulted in research efforts focusing on the use of particle-based drug delivery systems for the stimuli-responsive release of drugs in the skin and skin appendages, i.e. hair follicles and sebaceous glands. However, effective and innocuous trigger mechanisms which result in the release of the drugs from the nanocarriers upon reaching the target structures are still lacking. For the first time, the present study demonstrated the photo-activated release of the model drug fluorescein isothiocyanate (FITC) from topically applied gold nanoparticle-doped bovine serum albumin (AuNPs-doped BSA) particles (approx. 545nm) using water-filtered infrared A (IRA) radiation in the hair follicles of an ex vivo porcine skin model. The IRA radiation-induced plasmonic heating of the AuNPs results in the partial decomposition or opening of the albumin particles and release the model drug, while control particles without AuNPs show insignificant release. The results demonstrate the feasibility of using IRA radiation to induce release of encapsulated drugs from plasmonic nanocarriers for the targeting of follicular structures. However, the risk of radiation-induced skin damage subsequent to repeated applications of high infrared dosages may be significant. Future studies should aim at determining the suitability of lower infrared A dosages, such as for medical treatment regimens which may necessitate repeated exposure to therapeutics.

STATEMENT OF SIGNIFICANCE

Follicular targeting using nanocarriers is of increasing importance in the prophylaxis and treatment of dermatological or other diseases. For the first time, the present study demonstrated the photo-activated release of the model drug fluorescein isothiocyanate (FITC) from topically applied gold nanoparticle-doped bovine serum albumin (AuNPs-doped BSA) particles using water-filtered infrared A (IRA) radiation in the hair follicles of an ex vivo porcine skin model. The results demonstrate the feasibility of using wIRA radiation to induce release of encapsulated drugs for the targeting of follicular structures, and provide a new vision on the development of optically addressable delivery systems for controlled release of drugs in the skin and skin appendages, i.e. hair follicles and sebaceous glands.

Clinical use of cold atmospheric pressure argon plasma in chronic leg ulcers: A pilot study

OBJECTIVE

In the age of multiresistant microbes and the increasing lack of efficient antibiotics, conventional antiseptics play a critical role in the prevention and therapy of wound infections. Recent studies have demonstrated the antiseptic effects of cold atmospheric pressure plasma (APP). In this pilot, study we investigate the overall suitability of one of the first APP sources for wound treatment focusing on its potential antimicrobial effects.

METHOD

The wound closure rate and the bacterial colonisation of the wounds were investigated. Patients suffering from chronic leg ulcers were treated in a clinical controlled monocentric trial with either APP or octenidine (OCT). In patients who presented with more than one ulceration in different locations, one was treated with APP and the other one with OCT. Each group was treated three times a week over a period of two weeks. The antimicrobial efficacy was evaluated immediately after and following two weeks of treatment.

RESULTS

Wounds treated with OCT showed a significantly higher microbial reduction (64%) compared to wounds treated with APP (47%) immediately after the treatment. Over two weeks of antiseptic treatment the bacterial density was reduced within the OCT group (-35%) compared to a slight increase in bacterial density in the APP-treated group (+12%). Clinically, there were no signs of delayed wound healing observed in either group and both treatments were well tolerated.

CONCLUSION

The immediate antimicrobial effects of the APP prototype source were almost comparable to OCT without any signs of cytotoxicity. This pilot study is limited by current configurations of the plasma source, where the narrow plasma beam made it difficult to cover larger wound surface areas and in order to avoid untreated areas of the wound bed, smaller wounds were assigned to the APP-treatment group. This limits the significance of AAP-related effects on the wound healing dynamics, as smaller wounds tend to heal faster than larger wounds. However, clinical wound healing studies on a larger scale now seem justifiable. A more advanced plasma source prototype allowing the treatment of larger wounds will address APP's influence on healing dynamics, synergetic treatment with current antiseptics and effects on multiresistant bacteria.

In vivo study for the discrimination of cancerous and normal skin using fibre probe-based Raman spectroscopy

Raman spectroscopy has proved its capability as an objective, non-invasive tool for the detection of various melanoma and non-melanoma skin cancers (NMSC) in a number of studies. Most publications are based on a Raman microspectroscopic ex vivo approach. In this in vivo clinical evaluation, we apply Raman spectroscopy using a fibre-coupled probe that allows access to a multitude of affected body sites. The probe design is optimized for epithelial sensitivity, whereby a large part of the detected signal originates from within the epidermal layer's depth down to the basal membrane where early stages of skin cancer develop. Data analysis was performed on measurements of 104 subjects scheduled for excision of lesions suspected of being malignant melanoma (MM) (n = 36), basal cell carcinoma (BCC) (n = 39) and squamous cell carcinoma (SCC) (n = 29). NMSC were discriminated from normal skin with a balanced accuracy of 73% (BCC) and 85% (SCC) using partial least squares discriminant analysis (PLS-DA). Discriminating MM and pigmented nevi (PN) resulted in a balanced accuracy of 91%. These results lie within the range of comparable in vivo studies and the accuracies achieved by trained dermatologists using dermoscopy. Discrimination proved to be unsuccessful between cancerous lesions and suspicious lesions that had been histopathologically verified as benign by dermoscopy.

Combined antibacterial effects of tissue-tolerable plasma and a modern conventional liquid antiseptic on chronic wound treatment

Potential antimicrobial effects of sequential applications of tissue-tolerable plasma (TTP) and the conventional liquid antiseptic octenidine dihydrochloride (ODC) were investigated. 34 patients with chronic leg ulcers were treated with TTP, ODC or a combination of both. The bacterial colonization was measured semi-quantitatively before and immediately after treatment and changes in the microbial strains' compositions before and after antiseptic treatments were analyzed. All antiseptic procedures reduced the bacterial counts significantly. The sequential application of TTP and ODC displayed the highest antimicrobial efficacy. Me combined use of TTP and conventional antiseptics might represent the most efficient strategy for antiseptic treatment of chronic wounds.

Influence of mechanical stress on palmoplantar erythrodysesthesia--a case report

BACKGROUND

Cutaneous adverse events can have an important negative influence on quality of life and compliance in affected patients. Palmoplantar erythrodysesthesia (PPE; hand-foot syndrome) is a cutaneous toxicity associated with chemotherapeutic treatment, which necessitates treatment interruption or dose reduction in severe cases. This case report of pegylated liposomal doxorubicin-induced PPE shows the influence of mechanical stress on the development of skin lesions in various locations and the importance of patient education and compliance.

CASE REPORT

We present the case of a 43-year-old female patient diagnosed with ovarian cancer and having undergone surgical and chemotherapeutic treatment. The development of extensive grade 3 PPE affecting numerous areas of the body particularly exposed to mechanical pressure necessitated dermatological treatment. The combination of local application of an antioxidant-containing ointment and the patient's compliance made it possible to continue chemotherapy without interruption or dose reduction.

CONCLUSION

The development of PPE often limits the use of chemotherapeutic agents, and this case report can provide a possible therapeutic and preventive strategy for affected patients.

New strategies for preoperative skin antisepsis

During the past decades, encouraging progress has been made in the prevention of surgical site infections (SSI). However, as SSI still occur today, strategic prevention measures such as standardized skin antisepsis must be implemented and rigorously promoted. Recent discoveries in skin physiology necessitate the development of novel antiseptic agents and procedures in order to ameliorate their efficacy. In particular, alternate target structures in the skin need to be taken into consideration for the development of the next generation of antiseptics. Recent investigations have shown that a high number of microorganisms are located within and in the close vicinity of the hair follicles. This suggests that these structures are an important reservoir of bacterial growth and activity in human skin. To date, it has not been fully elucidated to what extent conventional liquid antiseptics sufficiently target the hair follicle-related microbial population. Modern technologies such as tissue-tolerable plasma (TTP) have been tested for their potential antiseptic efficiency by reducing the bacterial load in the skin and in the hair follicles. First experiments using liposomes to deliver antiseptics into the hair follicles have been evaluated for their potential clinical application. The present review evaluates these two innovative methods for their efficacy and applicability in preoperative skin antiseptics.

Palmoplantar erythrodysesthesia-like skin symptoms in patients under various chemotherapeutics: preventive and therapeutic options

BACKGROUND/AIMS

The palmoplantar erythrodysaesthesia (PPE) is an inflammatory cutaneous side effect in patients under chemotherapy with pegylated liposomal doxorubicin (PLD), with indications that also other chemotherapeutics induce similar side effects. Recently, it has been demonstrated that PLD escapes with the sweat onto the skin inducing radical-forming processes that damage the skin. The topical application of antioxidants with a high radical protection factor has proven to be a very efficient prevention strategy for PLD-treated patients.

METHODS

68 patients, who had been treated with 12 different chemotherapeutics and experienced side effects similar to PPE, were treated with a meanwhile commercially available ointment.

RESULTS

At the beginning of the therapy, 46 patients suffered from a PPE of severity grade III, while in 22 patients a PPE of severity grade II was diagnosed. The application of the ointment resulted in a significant improvement of the clinical symptoms and the skin status in all these patients; their chemotherapies could be continued.

CONCLUSION

The obtained results suggest that radical-forming processes play an essential role in a great number of chemotherapeutics which induce dermal side effects. The topical application of the antioxidant-containing ointment proved to be a good therapeutic option which needs further evaluation.

Comparative study of hair follicle morphology in eight mammalian species and humans

BACKGROUND

The objective of the present study was the investigation of hair follicle morphology in eight mammalian species in order to evaluate the species-specific contribution of hair follicles to skin penetration particularly with regard to the utilization of the different animal species as skin models for human skin.

METHODS

Cyanoacrylate skin surface biopsy method (CSSB), light microscopy and also digital photography were used for the measurements of hair follicle morphology.

RESULTS

The results revealed species-specific differences regarding the pattern of hair follicle distribution and also differences with regard to hair follicle parameters and characteristics. The results also showed that hair follicles generally possess enormous reservoir capacities, regarding the follicular volume. In all examined species, hair follicles reached at least one-fifth of stratum corneum storage capacity. The results were compared with human data obtained in a previous study.

CONCLUSION

With regard to hair follicle morphology and skin structure, the porcine skin seems to be the most appropriate skin model for human skin analog to previous investigations, whereas the skin of dog, cat, and rabbit showed the most significant differences.