PEDOT coated microneedles towards electrochemically assisted skin sampling

Skin sampling is a diagnostic procedure based on the analysis of extracted skin tissues and/or the observation of biomarkers in bodily fluids. Sampling using microneedles (MNs) that minimize invasiveness is gaining attention over conventional biopsy/blood lancet. In this study, new MNs for electrochemically assisted skin sampling are reported, specifically tailored for combined skin tissue biopsy and interstitial fluid (ISF) extraction. To overcome risks associated with using metal MNs, a highly electroactive, mechanically flexible, and biocompatible organic conducting polymer (CP) coated onto plastic is chosen as an alternative. Two different variants of doped poly(3,4-ethylenedioxythiophene) are coated on polymethyl methacrylate and used in combination as a MN pair with subsequent testing via a variety of electrochemical techniques to (i) give real-time information of the MN penetration depth into the skin, and (ii) yield new information on various salts present in the ISF. The MN skin sampler shows the ability to extract ions from the hydrated excised skin as a step towards in vivo ISF extraction. The presence of ions was analyzed using X-ray photoelectron spectroscopy. This added chemical information in conjunction with the existing biomarker analysis increases opportunity for disease/condition detection. For example, in the case of psoriasis, information about salt in the skin is invaluable in combination with pathogenic gene expression for diagnosis.

Assessment of a Diagnostic Classification System for Management of Lesions to Exclude Melanoma

Importance

The proposed MOLEM (Management of Lesion to Exclude Melanoma) schema is more clinically relevant than Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MATH-Dx) for the management classification of melanocytic and nonmelanocytic lesions excised to exclude melanoma. A more standardized way of establishing diagnostic criteria will be crucial in the training of artificial intelligence (AI) algorithms.

Objective

To examine pathologists' variability, reliability, and confidence in reporting melanocytic and nonmelanocytic lesions excised to exclude melanoma using the MOLEM schema in a population of higher-risk patients.

Design, Setting, and Participants

This cohort study enrolled higher-risk patients referred to a primary care skin clinic in New South Wales, Australia, between April 2019 and December 2019. Baseline demographic characteristics including age, sex, and related clinical details (eg, history of melanoma) were collected. Patients with lesions suspicious for melanoma assessed by a primary care physician underwent clinical evaluation, dermoscopy imaging, and subsequent excision biopsy of the suspected lesion(s). A total of 217 lesions removed and prepared by conventional histologic method and stained with hematoxylin-eosin were reviewed by up to 9 independent pathologists for diagnosis using the MOLEM reporting schema. Pathologists evaluating for MOLEM schema were masked to the original histopathologic diagnosis.

Main Outcomes and Measures

Characteristics of the lesions were described and the concordance of cases per MOLEM class was assessed. Interrater agreement and the agreement between pathologists' ratings and the majority MOLEM diagnosis were calculated by Gwet AC1 with quadratic weighting applied. The diagnostic confidence of pathologists was then assessed.

Results

A total of 197 patients were included in the study (102 [51.8%] male; 95 [48.2%] female); mean (SD) age was 64.2 (15.8) years (range, 24-93 years). Overall, 217 index lesions were assessed with a total of 1516 histological diagnoses. Of 1516 diagnoses, 677 (44.7%) were classified as MOLEM class I; 120 (7.9%) as MOLEM class II; 564 (37.2%) as MOLEM class III; 114 (7.5%) as MOLEM class IV; and 55 (3.6%) as MOLEM class V. Concordance rates per MOLEM class were 88.6% (class I), 50.8% (class II), 76.2% (class III), 77.2% (class IV), and 74.2% (class V). The quadratic weighted interrater agreement was 91.3%, with a Gwet AC1 coefficient of 0.76 (95% CI, 0.72-0.81). The quadratic weighted agreement between pathologists' ratings and majority MOLEM was 94.7%, with a Gwet AC1 coefficient of 0.86 (95% CI, 0.84-0.88). The confidence in diagnosis data showed a relatively high level of confidence (between 1.0 and 1.5) when diagnosing classes I (mean [SD], 1.3 [0.3]), IV (1.3 [0.3]) and V (1.1 [0.1]); while classes II (1.8 [0.2]) and III (1.5 [0.4]) were diagnosed with a lower level of pathologist confidence (≥1.5). The quadratic weighted interrater confidence rating agreement was 95.2%, with a Gwet AC1 coefficient of 0.92 (95% CI, 0.90-0.94) for the 1314 confidence ratings collected. The confidence agreement for each MOLEM class was 95.0% (class I), 93.5% (class II), 95.3% (class III), 96.5% (class IV), and 97.5% (class V).

Conclusions and Relevance

The proposed MOLEM schema better reflects clinical practice than the MPATH-Dx schema in lesions excised to exclude melanoma by combining diagnoses with similar prognostic outcomes for melanocytic and nonmelanocytic lesions into standardized classification categories. Pathologists' level of confidence appeared to follow the MOLEM schema diagnostic concordance trend, ie, atypical naevi and melanoma in situ diagnoses were the least agreed upon and the most challenging for pathologists to confidently diagnose.

Elongated microparticles tuned for targeting hyaluronic acid delivery to specific skin strata

OBJECTIVE

Microneedle or fractional laser applications are the most common topical delivery enhancement platforms. However, these methods of drug delivery are not skin strata specific. Drug delivery approaches which could target specific stratum of the skin remains a challenge. Elongated microparticles (EMPs) have been used in enhancing drug delivery into the skin. The aim of this study was to evaluate, for the first time, elongated silica microparticles with two different length profiles to enhance delivery of hyaluronic acid into different strata of human skin.

METHODS

Two types of EMPs - long (milled EMPs) or short (etched EMPs) length ranges were characterized. A prototypical liquid formulation (Fluorescent hyaluronic acid) with and without EMP enhancement were evaluated for hyaluronic acid delivery in ex-vivo human skin. High Performance Liquid Chromatography (HPLC), Typhoon fluorescence scanning system, Laser Scanning Confocal Microscopy (LSCM) and Reflectance Confocal Microscopy (RCM) were used to validate F-HA stability, visualize fluorescein in the skin, image the depth of F-HA delivery in the skin and define EMP penetration in skin strata, respectively. Statistical analysis was conducted using GraphPad Prism 6 software (GraphPad Software Inc, USA).

RESULTS

Fluorescein-hyaluronic acid was stable and EMP enhanced skin penetration. Reflectance confocal microscopy revealed that "etched EMP" penetrated the skin to the stratum spinosum level. The vast majority (97.8%; p < 0.001) of the etched EMP did not penetrate completely through the viable epidermis and no obvious penetration into the dermis. In contrast, milled EMP showed 41-fold increase in penetration compared to the etched EMP but penetrated beyond the dermoepidermal junction.

CONCLUSION

EMPs can enhance delivery of hyaluronic acid. Using EMPs with defined length distributions, which can be tuned for a specific stratum of the skin, can achieve targeted hyaluronic acid delivery.

A first-in-human study of BLZ-100 (tozuleristide) demonstrates tolerability and safety in skin cancer patients

BLZ-100 (tozuleristide) is an intraoperative fluorescent imaging agent that selectively detects malignant tissue and can be used in real time to guide tumor resection. The purpose of this study was to assess the safety, tolerability, and pharmacokinetics of BLZ-100 and to explore the pharmacodynamics of fluorescence imaging of skin tumors. In this first-in-human study, BLZ-100 was administered intravenously to 21 adult patients 2 days before excising known or suspected skin cancers. Doses were 1, 3, 6, 12, and 18 mg, with 3-6 patients/cohort. Fluorescence imaging was conducted before and up to 48 h after dosing. BLZ-100 was well tolerated. There were no serious adverse events, deaths, or discontinuations due to adverse events, and no maximum tolerated dose (MTD) was identified. Headache (n = 2) and nausea (n = 2) were the only BLZ-100 treatment-related adverse events reported for >1 patient. Median time to maximal serum concentration was <0.5 h. Exposure based on maximal serum concentrations increased in a greater than dose-proportional manner. For intermediate dose-levels (3-12 mg), 4 of 5 basal cell carcinomas and 4 of 4 melanomas were considered positive for BLZ-100 fluorescence. BLZ-100 was well tolerated at all dose levels tested and these results support further clinical testing of this imaging agent in surgical oncology settings. Clinicaltrials.gov: NCT02097875.

Towards data-driven quantification of skin ageing using reflectance confocal microscopy

INTRODUCTION

Evaluation of skin ageing is a non-standardized, subjective process, with typical measures relying coarse, qualitatively defined features. Reflectance confocal microscopy depth stacks contain indicators of both chrono-ageing and photo-ageing. We hypothesize that an ageing scale could be constructed using machine learning and image analysis, creating a data-driven quantification of skin ageing without human assessment.

METHODS

En-face sections of reflectance confocal microscopy depth stacks from the dorsal and volar forearm of 74 participants (36/18/20 training/testing/validation) were represented using a histogram of visual features learned using unsupervised clustering of small image patches. A logistic regression classifier was trained on these histograms to differentiate between stacks from 20- to 30-year-old and 50- to 70-year-old volunteers. The probabilistic output of the logistic regression was used as the fine-grained ageing score for that stack in the testing set ranging from 0 to 1. Evaluation was performed in two ways: on the test set, the AUC was collected for the binary classification problem as well as by statistical comparison of the scores for age and body site groups. Final validation was performed by assessing the accuracy of the ageing score measurement on 20 depth stacks not used for training or evaluating the classifier.

RESULTS

The classifier effectively differentiated stacks from age groups with a test set AUC of 0.908. Mean scores were significantly different when comparing age groups (mean 0.70 vs. 0.44; t = -6.62, p = 0.0000) and also when comparing stacks from dorsal and volar body sites (mean 0.64 vs. 0.53; t = 3.12, p = 0.0062). On the final validation set, 17 out of 20 depth stacks were correctly labelled.

DISCUSSION

Despite being limited to only coarse training information in the form of example stacks from two age groups, the trained classifier was still able to effectively discriminate between younger skin and older skin. Curiously, despite being only trained with chronological age, there was still evidence for measurable differences in age scores due to sun exposure-with marked differences in scores on sun-exposed dorsal sites of some volunteers compared with less sun-exposed volar sites. These results suggest that fine-grained data-driven quantification of skin ageing is achievable.

Motion Capture Quantification of User Variation in Topical Microparticle Application

Motion capture has the potential to shed light on topical drug delivery application. This approach holds promise both as a training tool, and for the development of skin technology, but first, this approach requires validation. Elongated microparticles (EMP) are a physical delivery enhancement technology that relies on a user working in the microparticles using a textured applicator. We used this approach to test the hypothesis that motion capture data can be used to characterize the topical application process. Motion capture was used to record participants while applying a mixture of EMP and sodium fluorescein to ex-vivo porcine skin samples. Treated skin was assessed using reflectance confocal and fluorescence microscopy. Image analysis was used to quantify the microparticle density and the presence of a fluorescent drug surrogate, sodium fluorescein. A strong correlation was present between applicator motion and microparticle and drug delivery profiles. There were quantitative and qualitative differences in the intra- and inter- user application methods that went beyond the level of training. Frequency and velocity of the applicator motion were key factors that correlated with EMP density. Our quantitative analysis of an experimental dermatological device supports the hypothesis that self-application may benefit from some form of digital monitoring or training with feedback. Our conclusion is that the integration of motion capture into experimental dermatological research offers an improved and quantifiable perspective that could be broadly useful with respect to topical applications, and with respect to the instruction provided to patients and clinicians.

A minimally invasive clinical model to test sunscreen toxicity based on oxidative stress levels using microbiopsy and confocal microscopy - a proof of concept study

OBJECTIVE

This proof-of-concept study demonstrated that using minimally invasive skin microsampling could enable significantly higher throughput of cosmetic testing in volunteers than conventional biopsy. Nanoparticle sunscreen was used as a model to test toxicity based on oxidative stress using microbiopsy and confocal imaging.

METHODS

Six volunteers were recruited for this study (3 males and 3 females). Zinc oxide nanoparticle containing topical formulation was prepared at 10% w/v. Each volunteer had 3 areas of 4 cm² each mapped on each inner forearm for a total of 6 treatment areas (intact/ tape-stripped and with/without treatment). The topical zinc-nanoparticle formulation was applied directly to volunteer skin (2mg/cm² ) for 2 hrs. Microbiopsied tissue from each treatment group was stained for reactive oxygen and nitrogen species in addition to mitochondrial superoxide. The stained samples were then imaged using confocal microscopy prior to image analysis.

RESULTS

Skin exposed to zinc oxide nanoparticles did not show any significant increases in oxidative stress. Zinc oxide nanoparticle tape-stripped skin resulted in signal significantly lower (P < 0.001) oxidative stress levels than t-butylated hydroxytoluene treated tape-stripped skin for oxidative stress markers. Topically applied zinc oxide nanoparticles had no detectable effect on the oxidative status in volunteer skin. No adverse reactions or effects were observed after all treatments including microbiopsy.

CONCLUSION

The data support the hypothesis that microbiopsy is a viable approach to study cosmeceutical- skin interactions in volunteers with capacity for molecular assays and high throughput with very low risk to the volunteer.

Physical drug delivery enhancement for aged skin, UV damaged skin and skin cancer: Translation and commercialization

This review analyses physical drug delivery enhancement technologies with a focus on improving UV damaged skin, actinic keratoses and non-melanoma skin cancer treatment. In recent years, physical drug delivery enhancement has been shown to enhance cosmeceutical and skin cancer treatment efficacy, but there are pros and cons to each approach which we discuss in detail. Mechanisms of action, clinical efficacy, experimental design, outcomes in academic publications, clinical trial reports and patents are explored to evaluate each technology with a critical, translation focused lens. We conclude that the commercial success of cosmeceutical applications, e.g. microneedles, will drive further innovation in this arena that will impact how actinic keratoses and non-melanoma skin cancers are clinically managed.

Advances and controversies in studying sunscreen delivery and toxicity

This review critically evaluates the sunscreen delivery and toxicity field. We chose to focus on approved sunscreens in this review. Optimal sunscreen use prevents skin cancer and photoageing but there is an important knowledge gap in sunscreen/skin interactions. Sunscreen delivery is a key for efficacy, but studying sunscreen delivery is not straightforward. We review the strengths and weaknesses of in vitro, excised skin and clinical approaches. Understanding positive and negative sunscreen effects on skin homeostasis is also challenging. The results in this field, especially in vitro testing, are controversial and experimental design varies widely which further supports disparities between some findings. We hypothesize that bias towards showing sunscreen toxicity to increase impact could be problematic. We explore that perception through a detailed review of experimental design, especially in cell culture models. Our conclusion is that emerging, non- and minimally invasive technologies are enabling new approaches to volunteer studies that could significantly improve knowledge of sunscreen delivery and interactions.

A review of microsampling techniques and their social impact

Conventional skin and blood sampling techniques for disease diagnosis, though effective, are often highly invasive and some even suffer from variations in analysis. With the improvements in molecular detection, the amount of starting sample quantity needed has significantly reduced in some diagnostic procedures, and this has led to an increased interest in microsampling techniques for disease biomarker detection. The miniaturization of sampling platforms driven by microsampling has the potential to shift disease diagnosis and monitoring closer to the point of care. The faster turnaround time for actionable results has improved patient care. The variations in sample quantification and analysis remain a challenge in the microsampling field. The future of microsampling looks promising. Emerging techniques are being clinically tested and monitored by regulatory bodies. This process is leading to safer and more reliable diagnostic platforms. This review discusses the advantages and disadvantages of current skin and blood microsampling techniques.

Absorbent Microbiopsy Sampling and RNA Extraction for Minimally Invasive, Simultaneous Blood and Skin Analysis

Conventional skin biopsy limits the clinical research that involves cosmetically sensitive areas or pediatric applications due to its invasiveness. Here, we describe the protocol for using an absorbent microneedle-based device, absorbent microbiopsy, for minimally invasive sampling of skin and blood mixture. Our goal is to help facilitate rapid progress in clinical research, the establishment of biomarkers for skin disease and reducing the risk for clinical research participants. In contrast to conventional skin biopsy techniques, the absorbent microbiopsy can be performed within seconds and does not require intensive training due to its simple design. In this report, we describe the use of absorbent microbiopsy, including loading and application, on a volunteer. Then, we show how to isolate RNA from the absorbed sample. Finally, we demonstrate the use of quantitative reverse transcription PCR (RT-qPCR) to quantify mRNA expression levels of both blood (CD3E and CD19) and skin (KRT14 and TYR). The methods that we describe utilize off the shelf kits and reagents. This protocol offers a minimally invasive approach for simultaneous sampling of skin and blood within the same absorbent microbiopsy matrix. We have found human ethics committees, clinicians and volunteers to be supportive of this approach to dermatological research.

Using elongated microparticles to enhance tailorable nanoemulsion delivery in excised human skin and volunteers

This study demonstrates, for the first time, clinical testing of elongated silica microparticles (EMP) combined with tailorable nanoemulsions (TNE) to enhance topical delivery of hydrophobic drug surrogates. Likewise, this is the first report of 6-carboxyfluorescein (a model molecule for topically delivered hydrophobic drugs) AM1 & DAMP4 (novel short peptide surfactants) used in volunteers. The EMP penetrates through the epidermis and stop at the dermal-epidermal junction (DEJ). TNE are unusually stable and useful because the oil core allows high drug loading levels and the surface properties can be easily controlled. At first, we chose alginate as a crosslinking agent between EMP and TNE. We initially incorporated a fluorescent lipophilic dye, DiI, as a hydrophobic drug surrogate into TNE for visualization with microscopy. We compared four different coating approaches to combine EMP and TNE and tested these formulations in freshly excised human skin. The delivery profile characterisation was imaged by dye- free coherent anti-Stoke Raman scattering (CARS) microscopy to detect the core droplet of TNE that was packed with pharmaceutical grade lipid (glycerol) instead of DiI. These data show the EMP penetrating to the DEJ followed by controlled release of the TNE. Freeze-dried formulations with crosslinking resulted in a sustained release profile, whereas a freeze-dried formulation without crosslinking showed an immediate burst-type release profile. Finally, we tested the crosslinked TNE coated EMP formulation in volunteers using multiphoton microscopy (MPM) and fluorescence-lifetime imaging microscopy (FLIM) to document the penetration depth characteristics. These forms of microscopy have limitations in terms of image acquisition speed and imaging area coverage but can detect fluorescent drug delivery through the superficial skin in volunteers. 6-Carboxyfluorescein was selected as the fluorescent drug surrogate for the volunteer study based on the similarity of size, charge and hydrophobicity characteristics to small therapeutic drugs that are difficult to deliver through skin. The imaging data showed a 6-carboxyfluorescein signal deep in volunteer skin supporting the hypothesis that EMP can indeed enhance the delivery of TNE in human skin. There were no adverse events recorded at the time of the study or after the study, supporting the use of 6-carboxyfluorescein as a safe and detectable drug surrogate for topical drug research. In conclusion, dry formulations, with controllable release profiles can be obtained with TNE coated EMP that can effectively enhance hydrophobic payload delivery deep into the human epidermis.

RNA-seq reveals more consistent reference genes for gene expression studies in human non-melanoma skin cancers

Identification of appropriate reference genes (RGs) is critical to accurate data interpretation in quantitative real-time PCR (qPCR) experiments. In this study, we have utilised next generation RNA sequencing (RNA-seq) to analyse the transcriptome of a panel of non-melanoma skin cancer lesions, identifying genes that are consistently expressed across all samples. Genes encoding ribosomal proteins were amongst the most stable in this dataset. Validation of this RNA-seq data was examined using qPCR to confirm the suitability of a set of highly stable genes for use as qPCR RGs. These genes will provide a valuable resource for the normalisation of qPCR data for the analysis of non-melanoma skin cancer.

Minimally invasive microbiopsies: a novel sampling method for identifying asymptomatic, potentially infectious carriers of Leishmania donovani

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Microbiopsy devices were designed to assess the infectiousness of asymptomatic Leishmania donovani carriers.

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The microbiopsy devices sample both skin tissues and blood, as do pool-feeding phlebotomine sand flies.

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Devices were tested on human volunteers in Ethiopia and proven effective, surpassing the sensitivity of finger-pricks.

Visceral leishmaniasis (VL) is a potentially lethal, sand fly-borne disease caused by protozoan parasites belonging to the Leishmania donovani species complex. There are several adequate methods for diagnosing VL, but the majority of infected individuals remain asymptomatic, comprising potential parasite reservoirs for transmission of the disease. The gold standard for assessing host infectiousness to biting vector insects is xenodiagnosis (i.e. scoring infection rates among insectary-reared insects that had fed on humans suspected of being infected). However, when it comes to sand flies and leishmaniasis, xenodiagnosis is an intricate operation burdened by logistical hurdles and ethical concerns that prevent its effective application for mass screening of widely dispersed communities, particularly in rural regions of underdeveloped countries. Minimally invasive microbiopsy (MB) devices were designed to penetrate the skin to a depth of ∼200 µm and absorb blood as well as skin cell lysates, mimicking the mode by which phlebotomine sand flies acquire blood meals, as well as their composition. MBs taken from 137 of 262 volunteers, living in endemic VL foci in Ethiopia, detected Leishmania parasites that could potentially be imbibed by feeding sand flies. Although the volume of MBs was 10-fold smaller than finger-prick blood samples, Leishmania DNA detection rates from MBs were significantly higher, implying that skin, more often than blood, was the source of parasites. Volunteers with histories of VL were almost as likely as healthy volunteers to test positive by MBs (southern Ethiopian focus: 95% CI: 0.35–2.59, P = 1.0. northern Ethiopian focus 0.87: 95% CI: 0.22–3.76, P = 1), suggesting the importance of asymptomatic patients as reservoirs of L. donovani. Minimally invasive, painless MBs should be considered for reliably and efficiently evaluating both L. donovani infection rates among large numbers of asymptomatic carriers and their infectiousness to blood-feeding sand flies.

Concurrent Reflectance Confocal Microscopy and Laser Doppler Flowmetry to Improve Skin Cancer Imaging: A Monte Carlo Model and Experimental Validation

Optical interrogation of suspicious skin lesions is standard care in the management of skin cancer worldwide. Morphological and functional markers of malignancy are often combined to improve expert human diagnostic power. We propose the evaluation of the combination of two independent optical biomarkers of skin tumours concurrently. The morphological modality of reflectance confocal microscopy (RCM) is combined with the functional modality of laser Doppler flowmetry, which is capable of quantifying tissue perfusion. To realize the idea, we propose laser feedback interferometry as an implementation of RCM, which is able to detect the Doppler signal in addition to the confocal reflectance signal. Based on the proposed technique, we study numerical models of skin tissue incorporating two optical biomarkers of malignancy: (i) abnormal red blood cell velocities and concentrations and (ii) anomalous optical properties manifested through tissue confocal reflectance, using Monte Carlo simulation. We also conduct a laboratory experiment on a microfluidic channel containing a dynamic turbid medium, to validate the efficacy of the technique. We quantify the performance of the technique by examining a signal to background ratio (SBR) in both the numerical and experimental models, and it is shown that both simulated and experimental SBRs improve consistently using this technique. This work indicates the feasibility of an optical instrument, which may have a role in enhanced imaging of skin malignancies.

Automated Segmentation of Skin Strata in Reflectance Confocal Microscopy Depth Stacks

Reflectance confocal microscopy (RCM) is a powerful tool for in-vivo examination of a variety of skin diseases. However, current use of RCM depends on qualitative examination by a human expert to look for specific features in the different strata of the skin. Developing approaches to quantify features in RCM imagery requires an automated understanding of what anatomical strata is present in a given en-face section. This work presents an automated approach using a bag of features approach to represent en-face sections and a logistic regression classifier to classify sections into one of four classes (stratum corneum, viable epidermis, dermal-epidermal junction and papillary dermis). This approach was developed and tested using a dataset of 308 depth stacks from 54 volunteers in two age groups (20–30 and 50–70 years of age). The classification accuracy on the test set was 85.6%. The mean absolute error in determining the interface depth for each of the stratum corneum/viable epidermis, viable epidermis/dermal-epidermal junction and dermal-epidermal junction/papillary dermis interfaces were 3.1 μm, 6.0 μm and 5.5 μm respectively. The probabilities predicted by the classifier in the test set showed that the classifier learned an effective model of the anatomy of human skin.

Recent advances in physical delivery enhancement of topical drugs

The skin has evolved to resist the penetration of foreign substances and particles. Effective topical drug delivery into and/or through the skin is hindered by these epidermal barriers. A range of physical enhancement methods has been developed to selectively overcome this barrier. This review discusses recent advances in physical drug delivery by broadly separating the techniques into two main areas; indirect and direct approaches. Indirect approaches consist of electrical, vibrational or laser instrumentation that creates pores in the skin followed by application of the drug. Direct approaches consist of mechanical disruption of the epidermis using techniques such as microdermabrasion, biolistic injectors and microneedles. Although, in general, physical techniques are yet to be established in a clinical setting, the potential gains of enhancing delivery of compounds through the skin is of great significance and will no doubt continue to receive much attention.

Enhanced delivery of nano- and submicron particles using elongated microparticles

Nanodermatology is a rapidly emerging field of study receiving significant interest because of its potential application in the prevention and treatment of skin diseases. However, nanoparticulate penetration into and through the skin is not feasible through topical application alone. Many physical and chemical approaches have been developed to enhance particulate penetration into skin. The most successful have been physical penetration enhancers. We have found that elongated microparticles can significantly improve topical nano- and microsphere delivery in an in vivo porcine model. The delivery efficiency was inversely related to the diameter of the payload. These data support a role for elongated microparticle enhanced delivery of nano- and submicron particulate cosmeceutical or therapeutic applications.

Effective cutaneous vaccination using an inactivated chikungunya virus vaccine delivered by Foroderm

Foroderm is a new cutaneous delivery technology that uses high-aspect ratio, cylindrical silica microparticles, that are massaged into the skin using a 3D-printed microtextured applicator, in order to deliver payloads across the epidermis. Herein we show that this technology is effective for delivery of a non-adjuvanted, inactivated, whole-virus chikungunya virus vaccine in mice, with minimal post-vaccination skin reactions. A single topical Foroderm-based vaccination induced T cell, Th1 cytokine and antibody responses, which provided complete protection against viraemia and disease after challenge with chikungunya virus. Foroderm vaccination was shown to deliver fluorescent, virus-sized beads across the epidermis, with beads subsequently detected in draining lymph nodes. Foroderm vaccination also stimulated the egress of MHC II(+) antigen presenting cells from the skin. Foroderm thus has potential as a simple, cheap, effective, generic, needle-free technology for topical delivery of vaccines.

Grading keratinocyte atypia in actinic keratosis: a correlation of reflectance confocal microscopy and histopathology

BACKGROUND

Actinic Keratosis (AK) is the clinical manifestation of cutaneous dysplasia of epidermal keratinocytes, with progressive trend towards squamous cell carcinoma.

OBJECTIVE

To evaluate the strength of the correlation between keratinocyte atypia, as detected by Reflectance Confocal Microscopy (RCM) and histopathology, and to develop a more objective atypia grading scale for RCM quantification, through a discrete ranking.

METHODS

A total of 48 AKs and two control areas (photodamaged and non-photodamaged skin) were selected for this study. All these areas were documented by RCM and biopsied for histopathology. One representative image of the epidermis was selected for RCM and for histopathology and used for side-by-side comparison with purpose written software. The assessor chose which of two images displayed more keratinocyte atypia, and an ordered list from the image showing the least to the most keratinocyte atypia was generated. Three evaluations were obtained for RCM and two for histopathology.

RESULTS

Good interobserver correlation was obtained for RCM and histopathology grading, with high concordance between RCM and histopathology grading.

CONCLUSIONS

Expert rater scan consistently distinguish different grades of cytological atypia. Non-invasive RCM data from in vivo imaging can be graded for keratinocyte atypia, comparable to histopathological grading.

BRAF wild-type melanoma in situ arising in a BRAF V600E mutant dysplastic nevus

IMPORTANCE

The BRAF V600E mutation accounts for the majority of BRAF mutations found in cutaneous melanoma and is also commonly found in nevi. We used dermoscopy-targeted sampling and a microbiopsy device coupled with DNA sequence analysis to highlight BRAF V600E heterogeneity within a multicomponent melanocytic proliferation. This sampling technique demonstrates the prospect of in vivo application in a clinical setting.

OBSERVATIONS

A man in his 50s with Fitzpatrick skin type II presented with an irregularly pigmented melanocytic lesion on his back that met melanoma-specific dermoscopic criteria, and diagnostic shave excision of the lesion was performed. Histopathologic analysis revealed a melanoma in situ arising in a dysplastic nevus. Dermoscopy-targeted microbiopsy specimens were taken across the lesion, and genotyping was carried out on extracted DNA samples for BRAF and NRAS mutations. The melanoma in situ showed only BRAF wild-type results, while the dysplastic nevus showed both BRAF wild-type and BRAF V600E mutations. Sequencing in all DNA samples revealed NRAS wild-type genotype.

CONCLUSIONS AND RELEVANCE

Dermoscopy-targeted sampling and genotyping of a melanoma in situ arising in a dysplastic nevus revealed a phenotype-genotype paradox that confounds the exclusive significance of BRAF and NRAS mutations in melanoma pathogenesis. Further studies are required to investigate the importance of other candidate genes linked to melanomagenesis.

BRAFV600E mutation status of involuting and stable nevi in dabrafenib therapy with or without trametinib

IMPORTANCE

Recent advances in targeting BRAFV600E mutations, which occur in roughly 50% of melanomas and 70% of benign nevi, have improved response rates and survival in patients with melanoma. With increased survival, the importance of other comorbidities increases and requires consideration in long-term management. This case report discusses dynamic dermoscopic nevus changes that occur during dabrafenib therapy and offers some conclusions regarding BRAF mutations and the changes.

OBSERVATIONS

A man in his 30s had been monitored with whole-body dermoscopy at roughly 7-month intervals as part of a nevus surveillance study. Fourteen months after his initial visit, metastases were found, and the patient entered a clinical trial of dabrafenib with or without trametinib therapy. Continued dermoscopic monitoring for the next 12 months revealed that approximately 50% of the existing acquired melanocytic nevi involuted, while the remaining nevi did not change. Biopsy findings from 1 unchanged and 1 involuted nevus showed BRAF wild type in the unchanged nevus, BRAFV600E mutation in the involuting nevus, and no malignant histopathologic characteristics in either one.

CONCLUSIONS AND RELEVANCE

Our observations indicate that a previously suggested hypothesis regarding involuting nevi in BRAF inhibitor therapy is correct: Nevi that involute while a patient is undergoing BRAF V600E inhibitor therapy possess the BRAF V600E mutation, while others that grow or remain unchanged are wild type. However larger-scale trials are required to gather conclusive data and create a more complete clinical picture.

Automated detection of actinic keratoses in clinical photographs

BACKGROUND

Clinical diagnosis of actinic keratosis is known to have intra- and inter-observer variability, and there is currently no non-invasive and objective measure to diagnose these lesions.

OBJECTIVE

The aim of this pilot study was to determine if automatically detecting and circumscribing actinic keratoses in clinical photographs is feasible.

METHODS

Photographs of the face and dorsal forearms were acquired in 20 volunteers from two groups: the first with at least on actinic keratosis present on the face and each arm, the second with no actinic keratoses. The photographs were automatically analysed using colour space transforms and morphological features to detect erythema. The automated output was compared with a senior consultant dermatologist's assessment of the photographs, including the intra-observer variability. Performance was assessed by the correlation between total lesions detected by automated method and dermatologist, and whether the individual lesions detected were in the same location as the dermatologist identified lesions. Additionally, the ability to limit false positives was assessed by automatic assessment of the photographs from the no actinic keratosis group in comparison to the high actinic keratosis group.

RESULTS

The correlation between the automatic and dermatologist counts was 0.62 on the face and 0.51 on the arms, compared to the dermatologist's intra-observer variation of 0.83 and 0.93 for the same. Sensitivity of automatic detection was 39.5% on the face, 53.1% on the arms. Positive predictive values were 13.9% on the face and 39.8% on the arms. Significantly more lesions (p<0.0001) were detected in the high actinic keratosis group compared to the no actinic keratosis group.

CONCLUSIONS

The proposed method was inferior to assessment by the dermatologist in terms of sensitivity and positive predictive value. However, this pilot study used only a single simple feature and was still able to achieve sensitivity of detection of 53.1% on the arms.This suggests that image analysis is a feasible avenue of investigation for overcoming variability in clinical assessment. Future studies should focus on more sophisticated features to improve sensitivity for actinic keratoses without erythema and limit false positives associated with the anatomical structures on the face.

The future of keratinocyte skin cancer surveillance: automated image analysis to identify and monitor keratinocyte dysplasia

Clinical assessment of actinic keratosis is known to be a variable process; however, there are currently no non-invasive alternatives for objectively assessing the condition besides excision and histopathology. While a number of technologies for examining potential actinic keratoses are under development, each of these still requires subjective human assessment. The existing approaches focus on assessing colour and texture features in clinical-scale images, such as those from dermoscopy and digital photography, and on structural or cellular characteristics in cellular-scale images, such as those from multiphoton microscopy and reflectance confocal microscopy. The future of actinic keratosis management is likely to be a combination of analysing regional photography to determine potential lesion locations and analysis of the structural and cellular features by reflectance confocal microscopy for an in vivo pathology diagnosis.

Reflectance confocal microscopy: hallmarks of keratinocyte cancer and its precursors

Actinic keratosis is a common result of severe sun damage and is usually present on sun-exposed skin. Reflectance confocal microscopy is a non-invasive clinical imaging modality that results in quasi-histological, en face skin images. In this chapter, we review the available literature and distill the common features of actinic keratosis, as seen by reflectance confocal microscopy. Finally, several examples are discussed in the context of matching clinical, histopathological and reflectance confocal microscopy images. Of all of the morphological features of actinic keratoses, the epidermal honeycomb pattern is the most telling when viewing the lesions using reflectance confocal microscopy. In the near future, we expect the definition of consensus criteria for diagnosing actinic keratoses and differentiating this precursor lesion.

Therapeutic gold, silver, and platinum nanoparticles

There are an abundance of nanoparticle technologies being developed for use as part of therapeutic strategies. This review focuses on a narrow class of metal nanoparticles that have therapeutic potential that is a consequence of elemental composition and size. The most widely known of these are gold nanoshells that have been developed over the last two decades for photothermal ablation in superficial cancers. The therapeutic effect is the outcome of the thickness and diameter of the gold shell that enables fine tuning of the plasmon resonance. When these metal nanoparticles are exposed to the relevant wavelength of light, their temperature rapidly increases. This in turn induces a localized photothermal ablation that kills the surrounding tumor tissue. Similarly, gold nanoparticles have been developed to enhance radiotherapy. The high-Z nature of gold dramatically increases the photoelectric cross-section. Thus, the photoelectric effects are significantly increased. The outcome of these interactions is enhanced tumor killing with lower doses of radiation, all while sparing tissue without gold nanoparticles. Silver nanoparticles have been used for their wound healing properties in addition to enhancing the tumor-killing effects of anticancer drugs. Finally, platinum nanoparticles are thought to serve as a reservoir for platinum ions that can induce DNA damage in cancer cells. The future is bright with the path to clinical trials is largely cleared for some of the less complex therapeutic metal nanoparticle systems.

High-contrast coherent terahertz imaging of porcine tissue via swept-frequency feedback interferometry

There is considerable interest in the interrogation of biological tissue at terahertz (THz) frequencies, largely due to the contrast in the optical properties of different biological tissues which occur in this electro-magnetic radiation band. Of particular interest are THz biomedical images, which have the potential to highlight different information than those acquired in other frequency bands, thereby providing an augmented picture of biological structures. In this work, we demonstrate the feasibility of an interferometric biological imaging technique using a THz quantum cascade laser (QCL) operating at 2.59 THz to perform coherent imaging of porcine tissue samples. We show the potential of this new THz biomedical imaging technique for in vivo studies, by virtue of its reflection geometry and useful tissue penetration depth enabled by the large THz powers emitted by the quantum cascade laser used in this work. The observed clustering of interferometric tissue signatures opens a pathway towards automatic techniques for the discrimination of healthy tissue types for the study of normal physiology and possible therapeutic approaches.

Microneedle enhanced delivery of cosmeceutically relevant peptides in human skin

Peptides and proteins play an important role in skin health and well-being. They are also found to contribute to skin aging and melanogenesis. Microneedles have been shown to substantially enhance skin penetration and may offer an effective means of peptide delivery enhancement. The aim of this investigation was to assess the influence of microneedles on the skin penetration of peptides using fluorescence imaging to determine skin distribution. In particular the effect of peptide chain length (3, 4, 5 amino acid chain length) on passive and MN facilitated skin penetration was investigated. Confocal laser scanning microscopy was used to image fluorescence intensity and the area of penetration of fluorescently tagged peptides. Penetration studies were conducted on excised full thickness human skin in Franz type diffusion cells for 1 and 24 hours. A 2 to 22 fold signal improvement in microneedle enhanced delivery of melanostatin, rigin and pal-KTTKS was observed. To our knowledge this is the first description of microneedle enhanced skin permeation studies on these peptides.

High aspect ratio elongated microparticles for enhanced topical drug delivery in human volunteers

Delivery of therapeutics into skin is hindered by the epidermal barriers. To overcome these barriers for the treatment of skin diseases, a cutaneous delivery method capable of field treatment using silica-elongated microparticles is developed. The microparticles are massaged into the skin using a 3D-printed microtextured applicator resulting in significant field-directed drug delivery enhancement.

Nanocomposite-strengthened dissolving microneedles for improved transdermal delivery to human skin

Delivery of drugs and biomolecules into skin has significant advantages. To achieve this, herein, a nanomaterial-strengthened dissolving microneedle patch for transdermal delivery is reported. The patch comprises thousands of microneedles, which are composed of dissolving polymers, nanomaterials, and drug/biomolecules in their interior. With the addition of nanomaterials, the mechanical property of generally weak dissolving polymers can be dramatically improved without sacrificing dissolution rate within skin. In this experiments, layered double hydroxides (LDH) nanoparticles are incorporated into sodium carboxymethylcellulose (CMC) to form a nanocomposite. The results show that, by adding 5 wt% of LDH nanoparticles into CMC, the mechanical strength significantly increased. Small and densely packed CMC-LDH microneedles penetrate human and pig skin more reliably than pure CMC ones and attractively the nanocomposite-strengthened microneedles dissolve in skin and release payload within only 1 min. Finally, the application of using the nanocomposite-strengthened microneedle arrays is tested for in vivo vaccine delivery and the results show that significantly stronger antibody response could be induced when compared with subcutaneous injection. These data suggest that nanomaterials could be useful for fabricating densely packed and small polymer microneedles that have robust mechanical properties and rapid dissolution rates and therefore potential use in clinical applications.

Zinc oxide nanoparticle removal from wounded human skin

Aim: Nanoparticle removal from skin is relevant given the concern over topical nanoparticle toxicity. Zinc oxide nanoparticles (ZnO-NPs) are commonly used in sunscreens and their use is currently debated. This study explores the penetration and removal of ZnO-NPs from injured skin. Materials & methods:Ex vivo/in vivo human skin was tape-stripped and/or microneedled followed by ZnO-NP application. After 2 h, treated skin was washed three-times using soapy water. Multiphoton tomography assessed the ZnO-NP signal before and after washing. Results: Washing once removed over 85 and 83% of ZnO-NP signal from ex vivo intact and tape-stripped skin, respectively (p < 0.05) but only 28% (p = 0.5) was removed from puncture sites. A similar trend was found in vivo with removal of 85 and 93% of ZnO-NP signal from intact and tape-stripped skin, respectively (p < 0.05). Conclusion: Washing is effective for the removal of ZnO-NPs from superficial layers of intact and tape-stripped skin, but not from puncture wounds.

Original submitted 5 July 2012; Revised submitted 3 October 2012; Published online 7 March 2013

Elongate microparticles for enhanced drug delivery to ex vivo and in vivo pig skin

The delivery of therapeutics and cosmaceuticals into and/or through the skin is hindered by epidermal barriers. To overcome the skin's barriers we have developed a novel cutaneous delivery method using high aspect ratio elongate microparticles (EMPs). Using ex vivo and in vivo pig skin we assess the penetration and delivery characteristics of the elongate microparticles. With reflectance confocal microscopy we observed that the elongate microparticles successfully penetrated the epidermis and upper dermis. Delivery was then assessed using two different length populations of EMPs, comparing their delivery profile to topical alone using sodium fluorescein and confocal microscopy. We observed a relatively uniform and continuous delivery profile in the EMP treated area within the upper layers of the skin--up to seven times greater than topical alone. Finally, we delivered two therapeutically relevant compounds (Vitamins A and B3), showing enhanced delivery using the EMPs. To our knowledge this is the first report using high aspect ratio elongate microparticles in this manner for enhanced topical delivery to the skin.

Feasibility of multiphoton microscopy-based quantification of antibiotic uptake into neutrophil granulocytes

Antibiotic levels in livestock are usually evaluated through destructive analysis. Taking advantage of the fluorescent properties of marbofloxacin (MBX) and trovafloxacin (TVX), multiphoton microscopy (MPM) was evaluated as a minimally invasive and nondestructive method to determine the penetration of TVX and MBX into sheep neutrophils. Standard curves were measured with drug-only solutions and suggested that MBX was more suited for this type of analysis. The intracellular concentration of both TVX and MBX was higher than the extracellular concentration after incubating neutrophils for 30 min at concentrations ranging from 0.1 to 100  μg/ml for both the drugs. The intracellular concentration of TVX increased with the extracellular concentration but was always greater than the extracellular concentration, suggesting active internalization. On the other hand, intracellular/extracellular ratio (I/E) peaked at 1.6-fold I/E for 1  μg/ml and then gradually decreased with increased concentration to 1.2-fold I/E at 100  μg/ml. For the first time, this study showed the use of MPM to quantify antibiotic uptake by sheep neutrophils and observed that both antibiotics were taken up by sheep neutrophils beyond extracellular levels.

Background free imaging of upconversion nanoparticle distribution in human skin

Widespread applications of nanotechnology materials have raised safety concerns due to their possible penetration through skin and concomitant uptake in the organism. This calls for systematic study of nanoparticle transport kinetics in skin, where high-resolution optical imaging approaches are often preferred. We report on application of emerging luminescence nanomaterial, called upconversion nanoparticles (UCNPs), to optical imaging in skin that results in complete suppression of background due to the excitation light back-scattering and biological tissue autofluorescence. Freshly excised intact and microneedle-treated human skin samples were topically coated with oil formulation of UCNPs and optically imaged. In the first case, 8- and 32-nm UCNPs stayed at the topmost layer of the intact skin, stratum corneum. In the second case, 8-nm nanoparticles were found localized at indentations made by the microneedle spreading in dermis very slowly (estimated diffusion coefficient, D(np) = 3-7 × 10(-12) cm(2) · s(-1)). The maximum possible UCNP-imaging contrast was attained by suppressing the background level to that of the electronic noise, which was estimated to be superior in comparison with the existing optical labels.

Microbiopsy engineered for minimally invasive and suture-free sub-millimetre skin sampling

We describe the development of a sub-millimetre skin punch biopsy device for minimally invasive and suture-free skin sampling for molecular diagnosis and research. Conventional skin punch biopsies range from 2-4 mm in diameter. Local anaesthesia is required and sutures are usually used to close the wound. Our microbiopsy is 0.50 mm wide and 0.20 mm thick. The microbiopsy device is fabricated from three stacked medical grade stainless steel plates tapered to a point and contains a chamber within the centre plate to collect the skin sample. We observed that the application of this device resulted in a 0.21 ± 0.04 mm wide puncture site in volunteer skin using reflectance confocal microscopy. Histological sections from microbiopsied skin revealed 0.22 ± 0.12 mm wide and 0.26 ± 0.09 mm deep puncture sites. Longitudinal observation in microbiopsied volunteers showed that the wound closed within 1 day and was not visible after 7 days. Reflectance confocal microscope images from these same sites showed the formation of a tiny crust that resolved by 3 weeks and was completely undetectable by the naked eye. The design parameters of the device were optimised for molecular analysis using sampled DNA mass as the primary end point in volunteer studies. Finally, total RNA was characterized. The optimised device extracted 5.9 ± 3.4 ng DNA and 9.0 ± 10.1 ng RNA. We foresee that minimally invasive molecular sampling will play an increasingly significant role in diagnostic dermatology and skin research.

Nanoscale biosensor for detection of reactive oxygen species

Noninvasive detection of biological responses to reactive oxygen species (ROS) in vivo could shed light on mechanisms at work in diverse areas like developmental dynamics, therapeutic effectiveness, drug discovery, pathogenic processes, and disease prevention. Research on ROS is usually dependent on in vitro models without translational relevance. Nanoscale (<100 nm) particulates are attractive carriers and platforms for biosensor technology due to their small size, flexible assembly, and favorable toxicity profiles. Intracellular signalling pathways activated in response to ROS have been well documented and mechanisms elaborated. Likewise, there is a wealth of genetic reporter systems that utilize fluorescent proteins capable of being monitored noninvasively. We combined these elements into a platform technology that utilizes nanoparticle-tethered synthetic genetic elements that respond to cellular response elements to report endogenous responses to oxidative insult through fluorescent gene expression. We envision the future of this technology to play a research role quantifying oxidative stress in vivo and a future clinical role as an automated theragnostic for ROS-related diseases. The production of this nanobiosensor technology utilizes off-the-shelf components and can be carried out in a molecular biology laboratory. Assessment of fluorescent protein expression can be done with noninvasive imaging and quantitative protein expression analysis. This is a flexible nanoparticle-based reporter system for monitoring in vivo responses to ROS.