Porphyrin distribution after topical aminolevulinic acid in a novel porcine model of sebaceous skin

Effect of various types of photodynamic therapy on inflammatory and non-inflammatory lesions in patients with acne: A network meta-analysis of randomized controlled trials

BACKGROUND

Recent studies have demonstrated that photodynamic therapy (PDT) is safe and effective in treating acne vulgaris. The present study aimed to evaluate various PDTs on inflammatory and non-inflammatory lesions in patients with acne by a network meta-analysis (NMA) of randomized controlled trials (RCTs).

METHODS

The researchers of this paper searched PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases from inception to March 2022 to identify suitable RCTs. The included studies were evaluated for methodological quality using the Cochrane bias risk assessment tool. Twenty-one RCTs were included, with a total sample size of 898 participants.

RESULTS

Network meta-analysis (NMA) revealed that indocyanine green (ICG) + near-infrared (NIR) diode laser, ICG+830 nm light-emitting diode (LED), indole-3-acetic acid (IAA) + 520 nm LED, and 5-aminolevulinic acid (ALA) + sunlight demonstrated obvious curative effects in patients with acne vulgaris. Importantly, ICG+NIR diode laser provided the greatest improvement in both inflammatory and non-inflammatory acne lesions (surface under the cumulative ranking curve [SUCRA]: 84.4% and 93.5%, respectively).

CONCLUSIONS

Based on the NWM and SUCRA ranking, ICG + NIR diode laser can be considered more effective in treating acne than the other PDTs of the RCTs. However, this conclusion should be interpreted with caution due to the limitations of the present study.

A split-face clinical trial of conventional red-light photodynamic therapy versus daylight photodynamic therapy for acne vulgaris

BACKGROUND

Photodynamic therapy (PDT) is considered an effective treatment for acne vulgaris. A significant drawback is pain during illumination. Daylight PDT (DL-PDT) is more tolerable.

OBJECTIVE

To assess and compare the efficacy and tolerability of DL-PDT and C-PDT for acne vulgaris through a prospective split-face trial.

METHODS AND MATERIALS

Fifteen patients underwent 4 treatment sessions at 3-week intervals. First, 5-aminolevulinic acid (ALA) was applied to the entire face, after which the face was divided into 2 symmetrical areas: The right side was exposed to sunlight, and the left half was illuminated with red light. Photographs were obtained and evaluated by two dermatologists blinded to the study protocol. The patients reported side effects and downtime.

RESULTS

There was a statistically significant decrease in the number and percent change of inflammatory and non-inflammatory lesions on both sides. Adverse effects were markedly decreased on the DL-PDT side compared to the C-PDT side (p < .01). The average downtime duration was longer for the C-PDT side (p < .001).

CONCLUSION

DL-PDT was at least as effective as C-PDT with fewer adverse effects and a shorter downtime duration.

Topical 5-aminolevulinic photodynamic therapy with red light vs intense pulsed light for the treatment of acne vulgaris: A spilit face, randomized, prospective study

5-Aminolevulinic acid photodynamic therapy (ALA-PDT) has been an effective method for treating acne vulgaris. Red light is the most widely used light source while Intense pulsed lights (IPL) is reported effective and well-tolerated. The purpose of this study was to evaluate the efficacy and adverse reactions of ALA-PDT with red light on acne compared with ALA-PDT with IPL.12 patients were recruited in the randomized, prospective and split-face study. 5% ALA cream were applied on the whole face with 2 hours' incubation before narrow band LED(633 ± 10 nm, 36 ∼ 108J/cm²) on one side of face and IPL(590∼1200 nm, 15∼17J/cm²) on the other side. Three treatment sessions were administered with 2-week interval each time and 8 weeks' follow up. The number of the total acne lesions and inflammatory lesions of the side treated by red light-PDT showed a relatively higher reduction rate that that by IPL-PDT (P < 0.05). Significant PpIX fluorescence decrease was observed only for the group of red light (P < 0.05). Lower pain intensity numeric rating scale values and Investigator's Global Severity Assessment (IGA) grading for erythema of the IPL side were observed (P<0.05).The results suggested that both red light and IPL are effective for ALA-PDT on acne vulgaris. ALA-PDT with red light may achieve better efficacy by more effective photobleaching of protoporphyrin IX (PpIX), whereas IPL may accomplish less adverse reactions and better tolerance.

Colonization of epidermal tissue by Staphylococcus aureus produces localized hypoxia and stimulates secretion of antioxidant and caspase-14 proteins

A partial-thickness epidermal explant model was colonized with green fluorescent protein (GFP)-expressing Staphylococcus aureus, and the pattern of S. aureus biofilm growth was characterized using electron and confocal laser scanning microscopy. The oxygen concentration in explants was quantified using microelectrodes. The relative effective diffusivity and porosity of the epidermis were determined using magnetic resonance imaging, while hydrogen peroxide (H2O2) concentration in explant media was measured by using microelectrodes. Secreted proteins were identified and quantified using elevated-energy mass spectrometry (MS(E)). S. aureus biofilm grows predominantly in lipid-rich areas around hair follicles and associated skin folds. Dissolved oxygen was selectively depleted (2- to 3-fold) in these locations, but the relative effective diffusivity and porosity did not change between colonized and control epidermis. Histological analysis revealed keratinocyte damage across all the layers of colonized epidermis after 4 days of culture. The colonized explants released significantly (P < 0.01) more antioxidant proteins of both epidermal and S. aureus origin, consistent with elevated H2O2 concentrations found in the media from the colonized explants (P< 0.001). Caspase-14 was also elevated significantly in the media from the colonized explants. While H2O2 induces primary keratinocyte differentiation, caspase-14 is required for terminal keratinocyte differentiation and desquamation. These results are consistent with a localized biological impact from S. aureus in response to colonization of the skin surface.

Acne Treatment Based on Selective Photothermolysis of Sebaceous Follicles with Topically Delivered Light-Absorbing Gold Microparticles

The pathophysiology of acne vulgaris depends on active sebaceous glands, implying that selective destruction of sebaceous glands could be an effective treatment. We hypothesized that light-absorbing microparticles could be delivered into sebaceous glands, enabling local injury by optical pulses. A suspension of topically applied gold-coated silica microparticles exhibiting plasmon resonance with strong absorption at 800 nm was delivered into human pre-auricular and swine sebaceous glands in vivo, using mechanical vibration. After exposure to 10-50 J cm(-2), 30 milliseconds, 800 nm diode laser pulses, microscopy revealed preferential thermal injury to sebaceous follicles and glands, consistent with predictions from a computational model. Inflammation was mild; gold particles were not retained in swine skin 1 month after treatment, and uptake in other organs was negligible. Two independent prospective randomized controlled clinical trials were performed for treatment of moderate-to-severe facial acne, using unblinded and blinded assessments of disease severity. Each trial showed clinically and statistically significant improvement of inflammatory acne following three treatments given 1-2 weeks apart. In Trial 2, inflammatory lesions were significantly reduced at 12 weeks (P=0.015) and 16 weeks (P=0.04) compared with sham treatments. Optical microparticles enable selective photothermolysis of sebaceous glands. This appears to be a well-tolerated, effective treatment for acne vulgaris.

Photodynamic therapy using a new formulation of 5-aminolevulinic acid for wrinkles in Asian skin: A randomized controlled split face study

BACKGROUND

Photodynamic therapy (PDT) with intense pulsed light (IPL) was proven effective for photorejuvenation. Recently, a new formulation of 0.5% 5-aminolevulinic acid (ALA) liposomal spray has been available. We designed a randomized split face study to evaluate usefulness and safety of IPL-PDT using a liposomal spray for periorbital wrinkles in Asians.

METHODS

Patients received three treatments every 3 weeks. The half of the face was treated with IPL-PDT and the other half with long pulsed Nd:YAG laser (LPNY). Skin fluorescence was measured using a spectrophotometer for the guidance of PDT treatment. Wrinkle score was marked by two-blinded independent dermatologists.

RESULTS

One patient dropped out due to 3-d lasting erythema on PDT side. The difference of mean reduction in lower and lateral periorbital wrinkle score on PDT side between the first and the last visit was statistically significant (p = 0.008 and p = 0.001, respectively). Lateral periorbital wrinkles treated with PDT showed better results than LPNY-treated sides. Twenty-five percent of patients reported good to excellent outcomes.

CONCLUSION

This study demonstrated that PDT with a liposomal spray provided modest wrinkle reduction without serious adverse effect and it might be a promising treatment modality for wrinkle treatment in Asians.

Fractional Skin Harvesting: Autologous Skin Grafting without Donor-site Morbidity

Background:

Conventional autologous skin grafts are associated with significant donor-site morbidity. This study was conducted to determine feasibility, safety, and efficacy of a new strategy for skin grafting based on harvesting small columns of full-thickness skin with minimal donor-site morbidity.

Methods:

The swine model was used for this study. Hundreds of full-thickness columns of skin tissue (~700 µm diameter) were harvested using a custom-made harvesting device, and then applied directly to excisional skin wounds. Healing in donor and graft sites was evaluated over 3 months by digital photographic measurement of wound size and blinded, computer-aided evaluation of histological features and compared with control wounds that healed by secondary intention or with conventional split-thickness skin grafts (STSG).

Results:

After harvesting hundreds of skin columns, the donor sites healed rapidly without scarring. These sites reepithelialized within days and were grossly and histologically indistinguishable from normal skin within 7 weeks. By contrast, STSG donor sites required 2 weeks for reepithelialization and retained scar-like characteristics in epidermal and dermal architecture throughout the experiment. Wounds grafted with skin columns resulted in accelerated reepithelialization compared with ungrafted wounds while avoiding the “fish-net” patterning caused by STSG.

Conclusion:

Full-thickness columns of skin can be harvested in large quantities with negligible long-term donor-site morbidity, and these columns can be applied directly to skin wounds to enhance wound healing.

Photodynamic therapy based on 5-aminolevulinic acid and its use as an antimicrobial agent

Exogenous 5-aminolevulinic acid (ALA) is taken up directly by bacteria, yeasts, fungi, and some parasites, which then induces the accumulation of protoporphyrin IX (PPIX). Subsequent light irradiation of PPIX leads to the inactivation of these organisms via photodamage to their cellular structures. ALA uptake and light irradiation of PPIX produced by host cells leads to the inactivation of other parasites, along with some viruses, via the induction of an immune response. ALA-mediated PPIX production by host cells and light irradiation result in the inactivation of other viruses via either the induction of a host cell response or direct photodynamic attack on viral particles. This ALA-mediated production of light-activated PPIX has been extensively used as a form of photodynamic therapy (PDT) and has shown varying levels of efficacy in treating conditions that are associated with microbial infection, ranging from acne and verrucae to leishmaniasis and onychomycosis. However, for the treatment of some of these conditions by ALA-based PDT, the role of an antimicrobial effect has been disputed and in general, the mechanisms by which the technique inactivates microbes are not well understood. In this study, we review current understanding of the antimicrobial mechanisms used by ALA-based PDT and its role in the treatment of microbial infections along with its potential medical and nonmedical applications.

Oil components modulate the skin delivery of 5-aminolevulinic acid and its ester prodrug from oil-in-water and water-in-oil nanoemulsions

The study evaluated the potential of nanoemulsions for the topical delivery of 5-aminolevulinic acid (ALA) and methyl ALA (mALA). The drugs were incorporated in oil-in-water (O/W) and water-in-oil (W/O) formulations obtained by using soybean oil or squalene as the oil phase. The droplet size, zeta potential, and environmental polarity of the nanocarriers were assessed as physicochemical properties. The O/W and W/O emulsions showed diameters of 216-256 and 18-125 nm, which, respectively, were within the range of submicron- and nano-sized dispersions. In vitro diffusion experiments using Franz-type cells and porcine skin were performed. Nude mice were used, and skin fluorescence derived from protoporphyrin IX was documented by confocal laser scanning microscopy (CLSM). The loading of ALA or mALA into the emulsions resulted in slower release across cellulose membranes. The release rate and skin flux of topical drug application were adjusted by changing the type of nanocarrier, the soybean oil O/W systems showing the highest skin permeation. This formulation increased ALA flux via porcine skin to 180 nmol/cm(2)/h, which was 2.6-fold that of the aqueous control. The CLSM results showed that soybean oil systems promoted mALA permeation to deeper layers of the skin from ∼100 μm to ∼140 μm, which would be beneficial for treating subepidermal and subcutaneous lesions. Drug permeation from W/O systems did not surpass that from the aqueous solution. An in vivo dermal irritation test indicated that the emulsions were safe for topical administration of ALA and mALA.

Photodynamic therapy for acne vulgaris: a critical review from basics to clinical practice: part II. Understanding parameters for acne treatment with photodynamic therapy

Photodynamic therapy requires a photosensitizer, oxygen, and activating light. For acne, pilosebaceous units are "target" structures. Porphyrins are synthesized in vivo from 5-aminolevulinic acid (ALA), particularly in pilosebaceous units. Different photosensitizers and drug delivery methods have been reported for acne treatment. There are a variety of porphyrin precursors with different pharmacokinetic properties. Among them, ALA and methyl-ester of ALA (MAL) are available for possible off-label treatment of acne vulgaris. In addition, various light sources, light dosimetry, drug incubation time, and pre- and posttreatment care also change efficacy and side effects. None of these variables has been optimized for acne treatment, but a number of clinical trials provide helpful guidance. In this paper, we critically analyze clinical trials, case reports, and series of cases published through 2009.

LEARNING OBJECTIVES

After completing this learning activity, participants should be able to analyze photodynamic therapy using 5-aminolevulinic acid and its derivates for acne treatment, predict the effectiveness and outcomes of photodynamic therapy using different parameters and/or different porphyrin-related photosensitizers, and assess and manage the side effects of porphyrin-based photodynamic therapy for acne.