Translational medicine in the field of ablative fractional laser (AFXL)-assisted drug delivery: A critical review from basics to current clinical status

Enhancement of skin permeability with thermal ablation techniques: concept to commercial products

Traditionally, the skin is considered as a protective barrier which acts as a highly impermeable region of the human body. But in recent times, it is recognized as a specialized organ that aids in the delivery of a wide range of drug molecules into the skin (intradermal drug delivery) and across the skin into systemic circulation (transdermal drug delivery, TDD). The bioavailability of a drug administered transdermally can be improved by several penetration enhancement techniques, which are broadly classified into chemical and physical techniques. Application of mentioned techniques together with efforts of various scientific and innovative companies had made TDD a multibillion dollar market and an average of 2.6 new transdermal drugs are being approved each year. Out of various techniques, the thermal ablation techniques involving chemicals, heating elements, lasers, and radiofrequency (RF) are proved to be more effective in terms of delivering the drug across the skin by disrupting the stratum corneum (SC). The reason behind it is that the thermal ablation technique resulted in improved bioavailability, quick treatment and fast recovery of the SC, and more importantly it does not cause any damage to underlying dermis layer. This review article mainly discussed about various thermal ablation techniques with commercial products and patents in each classes, and their safety aspects. This review also briefly presented anatomy of the skin, penetration pathways across the skin, and different generations of TDD.

Efficacy of Er,Cr:YSGG laser-assisted delivery of topical anesthesia in the oral mucosa

OBJECTIVE

Lasers which can reduce epithelium thickness will enhance the penetration of topical drugs. To date, no study has assessed the efficacy of this technique in the oral mucosa. The aim of this study was the evaluation of efficacy of this technique in increasing the effect of topical anesthesia in the oral mucosa.

MATERIALS AND METHODS

On 20 volunteers, half of the lower lip mucosa was irradiated with Er,Cr:YSGG laser with 2780 nm wavelength and 1.3 J/cm² energy for 1 min; then, topical lidocaine was applied on the entire lower lip mucosa. After 5 min, a 27-gauge needle was inserted to each half of the lip mucosa, and the length of the needle inserted into the mucosa without feeling pain was considered the depth of insertion. This measurement was repeated every 15 min for 1 h.

RESULTS

The mean depth of anesthesia at the control side was 6.95 ± 2.43, 8.45 ± 4.05, 6.5 ± 3.00, and 3.85 ± 2.08 mm at 5, 20, 35, and 60 min, respectively. These values at the test side were 12.25 ± 5.42, 13.25 ± 5.02, 11.4 ± 5.03, and 9.10 ± 5.84 mm, respectively. According to repeated-measures ANOVA, the effect of the type of the treatment on the depth of insertion was significant (P < 0.001).

CONCLUSIONS

The results showed that irradiation of Er,Cr:YSGG laser before the topical application of the anesthetic agents on the oral mucosa increases their efficacy.

CLINICAL RELEVANCE

Topical anesthesia is used to enhance dental procedures painlessly, but there is controversy in their efficacy. Laser-assisted drug delivery to the oral mucosa can enhance their efficacy.

Fractional CO2 laser-assisted Botulinum toxin type A delivery for the treatment of primary palmar hyperhidrosis

Intradermal injections of botulinum toxin type A (BTX-A) have been used successfully to treat patients with primary palmoplantar hyperhidrosis (PPH). However, problems with local injections of BTX-A for palmar hyperhidrosis include injection pain and reduced palmar muscle strength. This case series describes three patients with PPH. Patients were followed up for 3 months and assessed using the minor iodine starch test and the visual analog scale (VAS). Over two sessions within a 2-week interval, all patients received treatment on one palm, while the other palm served as the untreated control. Treated palms received fractional CO₂ laser therapy and immediate post-operative topical application of BTX-A solution for a total of 50 units. Sweat production was assessed based on the size of the sweat-producing area (measured by the minor iodine starch test) and subjective assessment of sweat production using the visual analog scale (VAS) at baseline, 2 weeks after the first treatment, and 1, 2, and 3 months after the second treatment. In the BTX-A-treated palm, the decrease in the mean sweat production was 51.6% at 2 weeks after the first treatment, and 88.5%, 67.8%, and 52.9%, at 1, 2, and 3 months after the final treatment when compared to the baseline. In the untreated palms, the decrease in the mean sweat production was 2% on all follow-ups when compared to the baseline. No adverse effect was observed in any patient. Fractional CO₂ laser is a safe technique for BTX-A delivery on the palm area and is demonstrated to be safe and effective in decreasing sweat secretion of hyperhidrosis palm.

Electronic Pneumatic Injection-Assisted Dermal Drug Delivery Visualized by Ex Vivo Confocal Microscopy

Background and Objectives

Electronic pneumatic injection (EPI) is a technique for dermal drug delivery, which is increasingly being used in clinical practice. However, only few studies have been reported on cutaneous drug distribution and related clinical endpoints. We aimed to visualize the immediate cutaneous drug distribution, changes in skin architecture, and related clinical endpoint of EPI.

Study Design/Materials and Methods

Acridine orange (AO) solution was administered to ex vivo porcine skin by EPI at pressure levels from 4 to 6 bar with a fixed injection volume of 50 µl and nozzle size of 200 µm. Immediate cutaneous distribution was visualized using ex vivo confocal microscopy (EVCM). Changes in skin architecture were visualized using both EVCM and hematoxylin and eosin‐stained cryosections.

Results

The defined immediate endpoint was a clinically visible papule formation on the skin. The pressure threshold to consistently induce a papule was 4 bar, achieving delivery of AO to the deep dermis (2319 µm axial and 5944 µm lateral distribution). Increasing the pressure level to 6 bar did not lead to significant differences in axial and lateral dispersion (P = 0.842, P = 0.905; respectively). A distinctively hemispherical distribution pattern was identified. Disruption of skin architecture occurred independently of pressure level, and consisted of subepidermal clefts, dermal vacuoles, and fragmented collagen.

Conclusions

This is the first study to relate a reproducible clinical endpoint to EPI‐assisted immediate drug delivery using EVCM. An EPI‐induced skin papule indicates dermal drug delivery throughout all layers of the dermis, independent of pressure level settings. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals LLC

Comparative Study of Traditional Ablative CO2 Laser-Assisted Topical Antifungal with only Topical Antifungal for Treating Onychomycosis: A Multicenter Study

BACKGROUND

The predominance of onychomycosis has been increasing recently. New medications and treatment modalities are being researched for better saturation of the antifungal agents through the nail plate topically because of the low resilience of some patients for the oral antifungal agents. Treatment of onychomycosis, mainly moderate to severe, can be very challenging, expensive, and time consuming.

OBJECTIVE

The objective of this clinical trial is to compare the efficacy and safety of a manually operated ablative CO₂ laser combined with a topical antifungal agent in patients with onychomycosis.

STUDY DESIGN

We conducted an open-label controlled prospective study of 160 eligible patients randomized into control and treatment groups with a 1:1 allocation in the department of dermatology in five different hospitals in Shanghai. It was a 6-month study where both groups were treated with a topical antifungal agent, with the treatment group also receiving ablation by the traditional CO₂ laser once a month for the first 3 months.

RESULTS

The clinical efficacy and mycological cure rate were significantly higher (p < 0.001) for the treatment group. Three (3.75%) patients from the control group and 18 (25%) patients from the treatment group achieved complete nail clearance along with negative potassium hydroxide and negative culture (primary endpoint) results at 24 weeks. Mycological clearance with at least moderate nail clearance (secondary endpoint) for the treatment group was also significantly higher (p < 0.001) for the laser treatment group. The laser treatment was mildly painful but tolerable by the patients. No drug interactions for both groups were encountered.

CONCLUSIONS

The ablative CO₂ laser is a primitive yet effective modality to be considered for the delivery of topical antifungal agents for the management of mild-to-severe onychomycosis. The laser has good tolerance in patients and is a common equipment found in most dermatology units even those without the latest medical technology.

S2k Guidelines for Cutaneous Basal Cell Carcinoma - Part 2: Treatment, Prevention and Follow-up

Basal cell carcinoma (BCC) is the most common malignant tumor among fair-skinned individuals, and its incidence had been steadily rising in the past decades. In order to maintain the highest quality of patient care possible, the German S2k guidelines were updated following a systematic literature search and with the participation of all professional societies and associations involved in the management of the disease. Part 2 addresses issues such as proper risk stratification, the various therapeutic approaches, and prevention as well as follow-up of patients with basal cell carcinoma.

Stimulation of collagen and elastin production in-vivo using 1,540 nm Er:Glass laser: assessment of safety and efficacy

Introduction: Induction of collagen and elastin remodeling in the human skin can be achieved by non-ablative fractional laser (NAFXL) and ablative fractional laser (AFXL). Our objective was to compare the safety, efficacy, tolerability, and ability to induce collagen and elastin remodeling of NAFXL versus AFXL in a series of treatments over time.Materials and Methods: In this prospective, proof of principle, single-case study, the safety, tolerability and efficacy of the laser systems were assessed via histopathology and clinical evaluations including photographs. Optical biopsies by means of multiphoton tomography (MPT) were used to evaluate the induction of collagen and elastin remodeling.Results: Treatments by both NAFXL and AFXL were well tolerated. The NAFXL system was found to be less painful and resulted in a shorter down- and healing times. MPT findings showed the superior capability of the AFXL procedure to induce collagen; on the other hand, elastin induction was more pronounced after NAFXL treatments.Conclusions: While NAFXL is as effective and safe as the traditional AFXL, it is better tolerated and has a shorter downtime. Serial optical biopsies over time over time can be a useful tool to assess the induction of collagen and elastin remodeling in the human skin.

Enhanced topical cutaneous delivery of indocyanine green after various pretreatment regimens: comparison of fractional CO2 laser, fractional Er:YAG laser, microneedling, and radiofrequency

Different devices have been used to enhance topical drug delivery. Aim of this study was to compare the efficacy of different skin pretreatment regimens in topical drug delivery. In six ex vivo human abdominal skin samples, test regions were pretreated with fractional CO₂ and Er:YAG laser (both 70 and 300 μm ablation depth, density of 5%), microneedling (500 μm needle length), fractional radiofrequency (ablation depth of ± 80–90 μm), and no pretreatment. The fluorescent agent indocyanine green (ICG) was applied. After 3 h, fluorescence intensity was measured at several depths using fluorescence photography. Significantly higher surface fluorescence intensities were found for pretreatment with fractional Er:YAG and CO₂ laser and for microneedling vs. no pretreatment (p < 0.05), but not for radiofrequency vs. no pretreatment (p = 0.173). Fluorescence intensity was highest for the Er:YAG laser with 300 μm ablation depth (mean 38.89 arbitrary units; AU), followed by microneedling (33.02 AU) and CO₂ laser with 300 μm ablation depth (26.25 AU). Pretreatment with both lasers with 300 μm ablation depth gave higher fluorescence intensity than with 70 μm ablation depth (Er:YAG laser, 21.65; CO₂ laser, 18.50 AU). Mean fluorescence intensity for radiofrequency was 15.27 AU. Results were comparable at 200 and 400 μm depth in the skin. Pretreatment of the skin with fractional CO₂ laser, fractional Er:YAG laser, and microneedling is effective for topical ICG delivery, while fractional radiofrequency is not. Deeper laser ablation results in improved ICG delivery. These findings may be relevant for the delivery of other drugs with comparable molecular properties.

Ablative fractional laser-assisted treatments for keratinocyte carcinomas and its precursors-Clinical review and future perspectives

Keratinocyte carcinomas (KC) are the most common malignant human neoplasms. Although surgery and destructive approaches are first-line treatments, topical therapies are commonly used. Due to limited uptake of topical agents across the skin barrier, clearance rates are often sub-optimal. In pre-clinical investigations, ablative fractional laser (AFL)-assisted drug delivery has demonstrated improved uptake of topical drugs commonly used to treat KC. In 22 clinical trials, the effect of AFL-assisted treatments has been investigated for actinic keratosis (AK; n = 14), Bowen's disease (BD; n = 5), squamous cell carcinoma (n = 1), and basal cell carcinoma (n = 7). The most substantial evidence currently exists for AFL-assisted photodynamic therapy for the treatment of AK and BD. AFL improved 12-months follow-up clearance rates of photodynamic therapy from 45.0-51.0% to 78.5-84.8% for AK and from 50.0-55.3% to 87.0-87.5% for BD. AFL-assisted pharmacological therapy is a promising tool for optimizing topical treatments of KC and its precursor lesions. Future developments include AFL-assisted immune activation, changing drug administration route of systemic therapies, and utilizing drug chemo-combinations.

Fundamentals of fractional laser-assisted drug delivery: An in-depth guide to experimental methodology and data interpretation

In the decade since their advent, ablative fractional lasers have emerged as powerful tools to enhance drug delivery to and through the skin. Effective and highly customizable, laser-assisted drug delivery (LADD) has led to improved therapeutic outcomes for several medical indications. However, for LADD to reach maturity as a standard treatment technique, a greater appreciation of its underlying science is needed. This work aims to provide an in-depth guide to the technology's fundamental principles, experimental methodology and unique aspects of LADD data interpretation. We show that drug's physicochemical properties including solubility, molecular weight and tissue binding behavior, are crucial determinants of how laser channel morphology influences topical delivery. Furthermore, we identify strengths and limitations of experimental models and drug detection techniques, interrogating the usefulness of in vitro data in predicting LADD in vivo. By compiling insights from over 75 studies, we ultimately devise an approach for intelligent application of LADD, supporting its implementation in the clinical setting.

Fractional laser-assisted topical delivery of bleomycin quantified by LC-MS and visualized by MALDI mass spectrometry imaging

Bleomycin exhibits antiproliferative effects desirable for use in dermato-oncology but topical use is limited by its 1415 Da molar mass. Ablative fractional laser (AFL)-assisted drug delivery has been shown to enhance drug uptake in skin. The aim of this study was with AFL to deliver bleomycin into skin, quantify uptake, and visualize biodistribution with mass spectrometry. In a Franz diffusion cell study, pig skin samples (n = 66) were treated with AFL (λ = 10,600 nm), 5% density, and 0, 5, 20, or 80 mJ/microbeam (mb) pulse energies before exposure to bleomycin for 0.5, 4, or 24 h. Bleomycin was quantified in biopsy cryosections at depths of 100, 500, and 1500 µm using high-performance liquid chromatography-mass spectrometry (LC-MS), and drug biodistribution was visualized for 80 mJ/mb samples by matrix assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). The pulse energies 5, 20, and 80 mJ/mb resulted in microscopic ablation zones (MAZs) reaching superficial, mid, and deep dermis respectively. Bleomycin was successfully delivered into the skin and deeper MAZs and longer exposure time resulted in higher skin concentrations. After 24 h, AFL exposure resulted in significant amounts of bleomycin throughout all skin layers (≥510 µg/cm3, p ≤ .002). In comparison, concentrations in intact skin exposed to bleomycin remained below limit of quantification. MALDI-MSI supported the quantitative LC-MS results by visualizing bleomycin biodistribution and revealing high uptake around MAZs with delivery into surrounding skin tissue. In conclusion, topical drug delivery of the large and hydrophilic molecule bleomycin is feasible, promising, and should be explored in an in vivo setting.

Drug penetration enhancement techniques in ablative fractional laser assisted cutaneous delivery of indocyanine green

Background and Objectives

Topical drug delivery can be increased by pretreatment of the skin with ablative fractional laser (AFXL). Several physical penetration enhancement techniques have been investigated to further improve AFXL‐assisted drug delivery. This study investigated the influence of three of these techniques, namely massage, acoustic pressure wave treatment, and pressure vacuum alterations (PVP) on the distribution of the fluorescent drug indocyanine green (ICG) at different depths in the skin after topical application on AFXL pretreated skin.

Materials and Methods

In ex vivo human skin, test regions were pretreated with AFXL (10,600 nm, channel depth 300 μm, channel width 120 μm, density 15%). Subsequently, ICG was applied, followed by massage, acoustic pressure wave treatment or PVP. ICG fluorescence intensity (FI) was assessed after 1, 3, and 24 hours at several depths using fluorescence photography.

Results

FI was higher when using enhancement techniques compared to control (AFXL‐only) up to 3 hours application time (P < 0.05). After 3 hours, mean surface FI was highest after acoustic pressure wave treatment (61.5 arbitrary units; AU), followed by massage (57.5AU) and PVP (46.9AU), respectively (for comparison: AFXL‐only 31.6AU, no pretreatment 14.9AU). Comparable or higher FI was achieved already after 1 hour with enhancement techniques compared to 3–24 hours application time without. After 24 hours, no significant differences between enhancement techniques and AFXL‐only were observed (P = 0.31).

Conclusion

Penetration enhancement techniques, especially acoustic pressure wave treatment and massage, result in improved drug accumulation in AFXL‐pretreated skin and reduce the application time needed. Lasers Surg. Med. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Laser-assisted delivery enhances topical uptake of the anticancer agent cisplatin

Systemic chemotherapy with the anticancer agent cisplatin is approved for advanced non-melanoma skin cancer (NMSC), but topical treatment is limited by insufficient cutaneous penetration. We studied the impact of ablative fractional laser (AFL) exposure on topical cisplatin’s pharmacokinetics and biodistribution in skin, using microscopic ablation zones reaching the mid- (MAZ-MD; 620 μm depth) and deep dermis (MAZ-DD; 912 μm depth) (λ = 10,600 nm, 196 MAZ/cm²). Assessed in an in vitro Franz cell model after 0.5-, 4-, 24 h topical exposure (n = 8), cisplatin delivery was greatly accelerated by AFL, shown by quantitative- and imaging-based inductively coupled plasma-mass spectrometry (ICP-MS). After 30 minutes, cisplatin concentrations were 91.5, 90.8 and 37.8 μg/cm³ in specific 100-, 500, and 1500 μm skin layers respectively, contrasting to 8.08, 3.12, 0.64 μg/cm³ in non-laser-exposed control skin (p < .001; control vs MAZ-MD). Supported by element bioimaging, the greatest relative increases occurred in the deep skin compartment and at later time points. After 24 h, cisplatin concentrations thus rose to 1829, 1732 and 773 μg/cm³, representing a 25-, 103- and 447-fold enhancement in the 100, 500, and 1500 μm deep skin layers versus corresponding controls (p < .001; MAZ-MD). A significant difference in cutaneous uptake using MAZ-MD and MAZ-DD was not shown at any time point, though deeper laser channels resulted in increased transdermal cisplatin permeation (p ≤ .015). In conclusion, AFL is a rapid, practical and existing skin treatment that may provide greatly enhanced uptake of topical cisplatin for treatment of superficial and deep skin cancer.

Advances in the treatment of traumatic scars with laser, intense pulsed light, radiofrequency, and ultrasound

Traumatic scarring is one of the most common complications after soft tissue injury caused by burns and trauma, which affects tens of millions of people worldwide every year. Traumatic scars diminish the quality of life due to disfigurement, symptoms of pain and itch, and restricted motion. The pathogenesis and pathophysiology of traumatic scar remain elusive. The management for traumatic scars is comprised of surgical and non-surgical interventions such as pressure therapy, silicone, corticosteroid, and radiotherapy, which are chosen by clinicians based on the physical examinations of scars. Recently, great progress in treating traumatic scars has been achieved by the development of novel technologies including laser, intense pulsed light (IPL), radiofrequency, and ultrasound. The aim of this review article was to summarize the advances of these technologies for traumatic scars intervention.

The Effect of the Fractional Carbon Dioxide Laser on Improving Minoxidil Delivery for the Treatment of Androgenetic Alopecia

Introduction: Recently, laser treatment for hair loss has become very popular. Laser-assisted drug delivery (LAD) is an evolving technology with potentially broad clinical applications. This work aims at inspecting the effect of the fractional carbon dioxide laser (CO₂ ) on improving the delivery of minoxidil in patients with androgenetic alopecia and detecting the role of the fractional CO₂ laser in its treatment. Methods: We enrolled 45 Egyptians with male androgenetic alopecia (MAGA); clinical grading was assessed based on Norwood-Hamilton classification. The patients were divided into 3 groups: the first group (combined group) received the fractional CO₂ laser session followed by topical application of minoxidil and also in between sessions; the second group received fractional CO₂ laser sessions only and 6 sessions with 2-week intervals were performed; the third group applied topical minoxidil only for 3 months. Global photographs and dermoscopic assessments were performed before treatment and 3 months after the treatment. Results: Several dermoscopic findings were detected, including peripilar sign, hair diversity, yellow spot, white dots, and arborizing red lines. The number of double hair units significantly increased after the treatment in the combined group. The mean number of hair after the treatment in the 3 groups significantly increased, mostly in the combined group. The hair thickness (thin & thick) significantly increased after the treatment in the combined group and the fractional group; however, in the minoxidil group, only thin hair thickness increased. In all the 3 groups, there was a significant improvement in hair count and thickness. Conclusion: The ablative fractional CO₂ laser alone or combined with minoxidil may serve as an additional treatment for MAGA.

Topical delivery of vismodegib using ablative fractional laser and micro-emulsion formulation in vitro

BACKGROUND AND OBJECTIVE

Hedgehog inhibitors such as vismodegib are targeted drugs widely used for the treatment of basal cell carcinomas; however, their use is significantly limited by frequent systemic side effects due to oral administration route. We aim to use ablative fractional laser (AFL) to enable the topical delivery of vismodegib to relevant dermal depths.

MATERIALS AND METHODS

Pig skin was treated in vitro with a fractional 10,600 nm CO₂ laser at 0 or 80 mJ/microbeam and exposed to vismodegib (6.4 mmol/L) in Franz-diffusion cells for 0.5, 4, and 24 hours (n = 54 samples), either formulated in a micro-emulsion composed of soybean oil and Tween 80 or dissolved in ethanol as vehicle control. Vismodegib biodistribution was studied at specific skin depths from 0 to 1,800 µm (incremental steps of 300 µm) by mass spectrometry.

RESULTS

Combination of AFL and vismodegib emulsion substantially enhanced the delivery of drug into the skin. Emulsion formulation alone yielded higher vismodegib skin concentrations compared to vehicle control in superficial and mid-dermis (0-900 µm, P = 0.002-0.015). The over-all highest concentration found (554.5 µmol/L) was reached at 24 hours in superficial (0-300 µm) AFL exposed skin, 7.6-fold higher than vehicle control (P = 0.002) and 9.7-101.6 fold higher than previously reported steady-state plasma concentrations in patients treated with oral vismodegib (5.5-56.9 µmol/L). Compared to intact skin, AFL exposure significantly increased skin concentrations of vismodegib even in deep skin layers (24 h, 900-1,800 µm, emulsion: 8.7-74.3 µmol/L vs. 0.0-0.0 µmol/L, P = 0.004-0.048; vehicle control: 23.7-50.6 µmol/L vs. 0.0-1.6 µmol/L, P = 0.002). The total delivery of vismodegib-emulsion into mid-deep dermal skin layers from 600 to 1,800 µm was for AFL exposed skin 8.2 fold higher than intact skin. Also, delivery of emulsion vismodegib by AFL was time-dependent as seen by the continuous increase in concentrations found over time, with highest uptake detected after 24 hours (4-24 hours, 0-900 µm, P = 0.002-0.004).

CONCLUSION

AFL enhances topical delivery of micro-emulsion formulated vismodegib, reaching concentrations similar to or above plasma concentrations previously reported in patients receiving oral vismodegib. Lasers Surg. Med. 51:79-87, 2019. © 2018 Wiley Periodicals, Inc.

Needle-free cutaneous delivery of living human cells by Er:YAG fractional laser ablation

BACKGROUND

Dermatological diseases, including most skin cancers and rare genetic conditions frequently originate in the epidermis. Targeted, topical cell-based therapy is a promising therapeutic strategy. Here, we present the first report demonstrating that fractional laser ablation enables local 'needle-free' intraepidermal delivery of living human cells.

METHODS

The cells penetrated porcine ear skin via microchannels created by Er:YAG fractional laser ablation; cell delivery was quantified using a haemocytometer. Cutaneous distribution was confirmed visually by laser scanning confocal microscopy and histological analysis.

RESULTS

Total cell delivery (sum of amounts permeated and deposited) after 24 h increased from 5.7 ± 0.1 x10⁵ to 9.6 ± 1.6 x10⁵ cells/cm² when increasing pore density from 300 to 600 pores/cm², - corresponding to 19- and 32-fold increases over the control. At 600 pores/cm², cell deposition was 136-fold greater than cell permeation - the latter most likely due to transport from micropores into appendageal pathways. Production of GFP post-delivery confirmed cell remained viability.

CONCLUSION

The results demonstrate the feasibility of using controlled laser microporation to achieve local 'needle-free' cutaneous delivery of living human cells to the epidermis and dermis. This raises the possibility of using this technique for targeted new approaches for dermatological therapy in these regions.

Device-assisted transdermal drug delivery

Transdermal drug delivery is a prospective drug delivery strategy to complement the limitations of conventional drug delivery systems including oral and injectable methods. This delivery route allows both convenient and painless drug delivery and a sustained release profile with reduced side effects. However, physiological barriers in the skin undermine the delivery efficiency of conventional patches, limiting drug candidates to small-molecules and lipophilic drugs. Recently, transdermal drug delivery technology has advanced from unsophisticated methods simply relying on natural diffusion to drug releasing systems that dynamically respond to external stimuli. Furthermore, physical barriers in the skin have been overcome using microneedles, and controlled delivery by wearable biosensors has been enabled ultimately. In this review, we classify the evolution of advanced drug delivery strategies based on generations and provide a comprehensive overview. Finally, the recent progress in advanced diagnosis and therapy through customized drug delivery systems based on real-time analysis of physiological cues is highlighted.

Treatment Strategies for Hypopigmentation in the Context of Burn Hypertrophic Scars

Dyspigmentation in burn scars can contribute to the development of psychosocial complications after injury and can be detrimental to social reintegration and quality of life for burn survivors. Although treatments for skin lightening to treat hyperpigmentation have been well reviewed in the literature, skin-darkening strategies to treat hypopigmentation have not. The following potential treatment options in the context of burn hypertrophic scar will be discussed: use of the melanocyte-keratinocyte transplantation procedure, use of ectopic synthetic analogues of alpha-melanocyte stimulating hormone to initiate melanogenesis, and use of FK506 to induce melanogenesis. A proposed future direction of research in laser-assisted drug delivery of inducers of local melanin production, with the hope of developing a targeted, effective approach to dyspigmentation in hypertrophic scar is also discussed.

Experimental Study of 5-fluorouracil Encapsulated Ethosomes Combined with CO2 Fractional Laser to Treat Hypertrophic Scar

OBJECTIVE

This study is designed to explore permeability of ethosomes encapsulated with 5-florouracil (5-FU) mediated by CO₂ fractional laser on hypertrophic scar tissues. Moreover, therapeutic and duration effect of CO₂ fractional laser combined with 5-FU encapsulated ethosomes in rabbit ear hypertrophic scar model will be evaluated.

METHODS

The permeated amount of 5-FU and retention contents of 5-FU were both determined by high-performance liquid chromatography (HPLC). Fluorescence intensities of ethosomes encapsulated with 5-FU (5E) labeled with Rodanmin 6GO (Rho) were measured by confocal laser scanning microscopy (CLSM). The permeability promotion of 5E labeled with Rho in rabbit ear hypertrophic scar mediated by CO₂ fractional laser was evaluated at 0 h, 6 h, 12 h, 24 h, 3 days and 7 days after the irradiation. The opening rates of the micro-channels were calculated according to CLSM. The therapeutic effect of 5EL was evaluated on rabbit ear hypertrophic scar in vivo. Relative thickness of rabbit ear hypertrophic scar before and after the treatment was measured by caliper method. Scar elevation index (SEI) of rabbit ear hypertrophic scar was measured using H&E staining.

RESULTS

The data showed that the penetration amount of 5EL group was higher than 5E group (4.15 ± 2.22 vs. 0.73 ± 0.33; p < 0.05) after 1-h treatment. Additionally, the penetration amount of 5EL was higher than that of the 5E group (107.61 ± 13.27 vs. 20.73 ± 3.77; p < 0.05) after 24-h treatment. The retention contents of the 5EL group also showed higher level than 5E group (24.42 ± 4.37 vs.12.25 ± 1.64; p < 0.05). The fluorescence intensity of Rho in hypertrophic scar tissues of the 5EL group was higher than that of the 5E group at different time points (1, 6, and 24 h). The opening rates of the micro-channels were decreased gradually within 24 h, and micro-channels were closed completely 3 days after the irradiation by CO₂ fractional laser. The relative thickness and SEI of rabbit ear hypertrophic scar after 7 days of treatment in the 5EL group were significantly lower than the 5E group.

CONCLUSION

CO₂ fractional laser combined with topical 5E can be effective in the treatment of hypertrophic scar in vivo and supply a novel therapy method for human hypertrophic scar.

[Laser treatment of basal cell carcinoma]

With a clear increase in the incidence and a continuously earlier onset, the main risk factors for the development of basal cell carcinoma are still exposure to sunlight, fair skin, immunosuppression, carcinogens such as arsenic, chronic irritations and certain genodermatoses. Treatment options for localized resectionable basal cell carcinoma include micrographically controlled surgery, simple excision, curettage, laser ablation, cryosurgery, imiquimod, 5‑fluorouracil, photodynamic treatment and radiotherapy. Non-surgical treatment options are more suited for cases in which surgical procedures lead to disfigurement or functional impairments or for patients with a high surgical risk. Laser treatment, ablative and non-ablative as monotherapy or in combination can represent a meaningful treatment option in selected cases. In recent years there has been an increase in knowledge about the indications and effects of laser treatment of basal cell carcinoma; nevertheless, further studies with a high level of evidence are necessary.

Update of Ablative Fractionated Lasers to Enhance Cutaneous Topical Drug Delivery

Ablative fractional lasers (AFXL) enhance uptake of therapeutics and this newly emerging field is called laser-assisted drug delivery (LAD). This new science has emerged over the past decade and is finding its way into clinical practice. LAD is poised to change how medicine delivers drugs. Topical and systemic application of pharmaceutical agents for therapeutic effect is an integral part of medicine. With topical therapy, the stratum corneum barrier of the skin impairs the ability of drugs to enter the body. The purpose of LAD is to alter the stratum corneum, epidermis, and dermis to facilitate increased penetration of a drug, device, or cell to its respected target. AFXL represents an innovative, non-invasive strategy to overcome the epidermal barrier. LAD employs three steps: (1) breakdown of the skin barrier with a laser, (2) optional use a laser for a therapeutic effect, (3) delivery of the medicine through laser channels to further enhance the therapeutic effect. The advantages of using lasers for drug delivery include the ease of accessibility, the non-invasive aspect, and its effectiveness. By changing the laser settings, one may use LAD to have a drug remain locally within the skin or to have systemic delivery. Many drugs are not intended for use in the dermis and so it has yet to be determined which drugs are appropriate for this technique. It appears this developing technology has the ability to be a new delivery system for both localized and systemic delivery of drugs, cells, and other molecules. With responsible development AFXL-assisted drug delivery may become a new important part of medicine.

Laser-Assisted Delivery to Treat Facial Scars

Treatment of facial scars is a multispecialty endeavor for optimal patient recovery. One new innovation helping in facial scar treatments are lasers. Fractional laser predictably (tunable) disrupts the barrier of the skin creating deep channels that allow the delivery of drug and cellular materials; this is called laser-assisted drug delivery (LAD). Without exception thus far, LAD has been found to enhance the local uptake of any drug or substance applied to the skin. These zones may be used postoperatively to deliver drugs and other substances to create an enhanced scar therapeutic response to drug or substance applied to the skin.