Vascular effects of photodynamic and pulsed dye laser therapy protocols

Photodynamic therapy mediated by methylene blue-loaded PEG accelerates skin mouse wound healing: an immune response

PURPOSE

Conventional approaches for enhancing wound healing may not always yield satisfactory results. Instead, we test the effectiveness of a newly developed photodynamic therapy (PDT) that uses methylene blue (MB) loaded with polyethylene glycol (PEG) (MB-PEG) hydrogel to accelerate wound healing process in mice.

METHODS

A dorsal skin incision with 6 mm punch which topically subjected to MB-PEG hydrogel and a low-level laser light of red light to assess the regeneration process of wounded skin. A total of 63 adult male CD1 mice divided into normal group (no treatment) and other wound groups received different treatments of laser (650 ± 5 nm and power intensity of 180 mW/cm2), MB-PEG, or PDT (MB-PEG followed by laser). The wound healing parameters were investigated by histological examination of the skin and measuring of proinflammatory cytokines at the early stage (48 h) and a late one on day 21.

RESULTS

at 48 h, the score of tissue granulation, inflammation, and angiogenesis process were markedly improved in wounded groups that received MB + PEG combined with laser compared to the group treated with laser alone. On day 21, a significant improvement of the inflammation was detected in the group treated with MB + PEG plus laser compared to the other groups. At 48 h, the upregulated serum levels of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in the wound group were significantly (P < 0.001) reduced in the group treated with MB + PEG combined with laser.

CONCLUSION

MB-PEG based hydrogel improves and accelerates wound closure in the context of laser compared to either single treatment.

Dose-response relationship of photobiomodulation therapy and oxidative stress markers in healing dynamics of diabetic neuropathic ulcers in Wistar rats

Purpose

Diabetic foot ulcers are reported to be the most expensive complications of diabetes, with high morbidity and mortality rates. If the necessary care is not provided for the wound to heal, the individual may end up amputating the affected feet. Photobiomodulation therapy is a promising non-pharmacological treatment option for wound healing. The objective of the present study is to establish a dose-response relationship between photobiomodulation therapy and oxidative stress markers in the healing dynamics of diabetic neuropathic ulcers in Wistar rats.

Methodology

Diabetic neuropathy was induced in 126 Albino Wistar rats. An excisional wound of an area of 2cm2 was made on the neuropathy-induced leg. Photobiomodulation therapy of dosages 4, 6, 8, 10, 12, and 15 J/cm2 of wavelengths 655 and 808 nm was irradiated. The control group animals were kept un-irradiated. The outcome measures were assessed during wound healing's inflammatory, proliferative and remodelling phases.

Results

In the experimental group, animals treated with photobiomodulation therapy at doses of 4, 6, and 8 J/cm2 showed better wound healing dynamics. Photobiomodulation therapy modulated the reactive oxygen species and antioxidant levels, thereby improving the oxidative status of the wound.

Conclusion

Photobiomodulation therapy of dosages 4, 6, and 8 J/cm2 is effective and is a promising adjuvant modality in treating diabetic neuropathic ulcers. There was a strong dose-response relationship in the experimental groups treated with 4, 6 and 8 J/ cm2.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-022-01157-2.

Optimal Fluence and Duration of Low-Level Laser Therapy for Efficient Wound Healing in Mice

Background

Low-level laser (light) therapy is a promising technology that stimulates healing, relieves pain and inflammation, and restores function in injured body parts. However, few studies have compared the effects of light-emitting diodes of different fluence levels or different treatment durations.

Objective

Here, we investigated the effects of various fluence levels and treatment durations on wound closure in mice.

Methods

Full-thickness wounds were created on the dorsal skin using an 8-mm diameter punch, and the wounds were irradiated at 1, 4, or 40 J/cm² for 5 consecutive days starting on day 1. To determine the optimal irradiation duration, wounds were irradiated at the most potent fluence of previous study for 5, 10, or 15 days. Photographic documentation, skin biopsies, and wound measurements were performed to compare the effects of different treatment parameters.

Results

The most effective fluence level was 40 J/cm² at day 5, as determined by monitoring wound closure. There were no statistically significant differences in wound healing with different durations.

Conclusion

We have shown that repeated exposure to low levels of light significantly stimulates wound healing in mice and demonstrated more efficient wound closure with certain fluences of 830 nm irradiation.

Effect of 632 nm He-Ne Laser on Gram-Positive Bacteria in Deep Partial Thickness Pediatric Burn: A Prospective Double-Blind Randomized Controlled Trial

Background. Burns are one of the most common injuries in pediatric population, gram-positive bacteria is the main pathogens responsible for wound infection that is the leading cause of morbidity and sometimes mortality in growing children with burn. Low level laser is a new treatment option that is increasingly used in the field of wound healing. Aim. To investigate the effect of He-Ne laser on gram-positive bacteria and healing time of deep second-degree pediatric burn. Methods. Thirty children of both genders aged from 2 to 9 years old with 2nd degree upper limb burn infected with gram-positive bacteria participated in this study. They were randomly assigned into two equal groups; either the control group (group A) received systematic antibiotic and 10 minutes’ placebo laser light, or the laser group (group B) received 632 nm laser light, 6 J/cm2 scanning technique for 10 minutes. All patients received regular wound care (dressing). The study protocol was once a day, 3 times / week for one month. Pre and post-treatment evaluation of wound culture and the healing time was recorded for both groups. Results. Wound culture of all children in both groups were negative after two weeks of the study and wound healing time was significantly shorter in the laser group (14.6±5.7 days) than the control group (27±7.3 days). Conclusion. He-Ne laser is an effective option of treatment for 2nd-degree pediatric burn as it has a bactericidal effect on gram-positive bacteria and accelerates wound healing process significantly.

Real-time photoacoustic sensing for photo-mediated ultrasound therapy

Photo-mediated ultrasound therapy (PUT) is a novel, noninvasive antimicrovascular approach that can treat neovascularization with high precision. We developed a photoacoustic (PA) sensing (PAS) system for PUT and achieved real-time PAS-guided PUT. Experiments performed on a chicken yolk sac membrane model demonstrated that PAS could monitor the treatment effect in a microvessel during PUT. Vessel shrinkage induced a decrease in the PA signal amplitude, while vessel rupture induced an abrupt increase in the PA signal amplitude. The integrated PUT and PAS system can significantly improve the safety and effectiveness of PUT, and may assist with clinical translation of this novel antimicrovascular technique.

Measurement of pO2 by luminescence lifetime spectroscopy: A comparative study of the phototoxicity and sensitivity of [Ru(Phen)3 ]2+ and PdTCPP in vivo

Dysfunctions in tissue metabolism can be detected at early stages by oxygen partial pressure (pO₂ ) measurement. The measurement of emission lifetimes offers very promising and non-invasive approach to estimate pO₂ in vivo. This study compares two extensively used oxygen sensors and assesses their in vivo oxygen sensitivity and phototoxic effect. Luminescence lifetime of Ru-polypyridyl complex and of Pd-porphyrin is measured in the Chick's Chorioallantoic Membrane (CAM) model with a dedicated optical fiber-based, time-resolved spectrometer. The Pd-porphyrin luminescence lifetimes measured in the CAM model exposed to different pO₂ levels are longer and have a broader dynamic range (10-100 μs) than those of Ru-polypyridyl complex (0.6-1 μs). The combined statistical analysis based on an estimate of the kurtosis and skewness, bootstrapping method and routine normality tests is performed. The indicators of the averages and signal to noise ratio stability are also calculated. The combination of several data processing allows selection of the better sensor for a given application. In particular, it is found that the advantage of Ru-polypyridyl complex over Pd-porphyrin is two-fold: i) Ru-polypyridyl complex datasets have consistently better statistical characteristics, ii) Ru-polypyridyl exhibits lower cytotoxicity.

High-precision, non-invasive anti-microvascular approach via concurrent ultrasound and laser irradiation

Antivascular therapy represents a proven strategy to treat angiogenesis. By applying synchronized ultrasound bursts and nanosecond laser irradiation, we developed a novel, selective, non-invasive, localized antivascular method, termed photo-mediated ultrasound therapy (PUT). PUT takes advantage of the high native optical contrast among biological tissues and can treat microvessels without causing collateral damage to the surrounding tissue. In a chicken yolk sac membrane model, under the same ultrasound parameters (1 MHz at 0.45 MPa and 10 Hz with 10% duty cycle), PUT with 4 mJ/cm² and 6 mJ/cm² laser fluence induced 51% (p = 0.001) and 37% (p = 0.018) vessel diameter reductions respectively. With 8 mJ/cm² laser fluence, PUT would yield vessel disruption (90%, p < 0.01). Selectivity of PUT was demonstrated by utilizing laser wavelengths at 578 nm or 650 nm, where PUT selectively shrank veins or occluded arteries. In a rabbit ear model, PUT induced a 68.5% reduction in blood perfusion after 7 days (p < 0.001) without damaging the surrounding cells. In vitro experiments in human blood suggested that cavitation may play a role in PUT. In conclusion, PUT holds significant promise as a novel non-invasive antivascular method with the capability to precisely target blood vessels.

Hemoporfin-mediated photodynamic therapy on normal vasculature: implications for phototherapy of port-wine stain birthmarks

Background

Port-wine stain (PWS) birthmarks currently are treated using a pulsed dye laser (PDL) combined with transient cooling of the epidermis. PDL treatment protocols utilize short pulses of light (585 or 595 nm wavelength) to heat selectively the microvasculature due to absorption by intravascular hemoglobin. Although most patients respond to PDL therapy, few experience complete removal of the PWS. An alternate treatment option to PDL therapy of PWS is photodynamic therapy (PDT). Research groups have reported on various photosensitizers for PDT of PWS, including Hemoporfin, Benzoporphyrin Derivative monoacid ring A, and talaporfin sodium.

Aim

Our aim was to evaluate, with an established preclinical in-vivo model, the efficacy of photodynamic therapy (PDT) with Hemoporfin to achieve persistent vascular shutdown.

Methods

To monitor the microvasculature, a dorsal window chamber was surgically installed on 24 adult mice. The PDT excitation source emitted 150mW of 532nm light, with an irradiance of 100mW/cm². A retroorbital injection of Hemoporfin (2 mg/kg) was performed to deliver the drug into the bloodstream. Laser irradiation was initiated immediately after injection. To monitor blood-flow dynamics in response to PDT, we used laser speckle imaging. We employed a dose-response experimental design to study the efficacy of Hemoporfin-mediated PDT to achieve persistent vascular shutdown observed on Day 7 after PDT.

Results

We observed four general hemodynamic responses to PDT: (1) At low radiant exposures, we did not observe any persistent vascular shutdown; (2) at intermediate radiant exposures, we observed delayed vascular shutdown effect with significant change to the vascular structure; (3) at intermediate radiant exposures, we observed an acute vascular shutdown effect with gradual restoration of blood flow and no significant changes to the vascular structure; and (4) at high radiant exposures, we observed acute vascular shutdown that persisted during the entire 7-day monitoring period, with no change in vascular structure. With light dose-response analysis, we estimated a characteristic radiant exposure of 359 J/cm² that was required to achieve persistent vascular shutdown observed on Day 7 after PDT.

Conclusions

The experimental data collectively suggest that Hemoporfin-mediated PDT can achieve persistent vascular shutdown of normal microvasculature. However, compared with our previous data using Talaporfin Sodium as photosensitizer, Hemoporfin-mediated PDT is less efficient and requires a considerably longer (~four times) irradiation time.

Relevance for patients

Patients with PWS lesions may benefit from the advantages that PDT potentially offers over conventional PDL therapy. PDT potentially is safer for patients of all skin types and more effective at treatment of recalcitrant lesions. Although clinical data suggest that Hemoporfin-mediated PDT is a promising alternative to PDL therapy, our results suggest that additional study of other photosensitizers is warranted.

The Role of Laser Speckle Imaging in Port-Wine Stain Research: Recent Advances and Opportunities

Here, we review our current knowledge on the etiology and treatment of port-wine stain (PWS) birthmarks. Current treatment options have significant limitations in terms of efficacy. With the combination of 1) a suitable preclinical microvascular model, 2) laser speckle imaging (LSI) to evaluate blood-flow dynamics, and 3) a longitudinal experimental design, rapid preclinical assessment of new phototherapies can be translated from the lab to the clinic. The combination of photodynamic therapy (PDT) and pulsed-dye laser (PDL) irradiation achieves a synergistic effect that reduces the required radiant exposures of the individual phototherapies to achieve persistent vascular shutdown. PDL combined with anti-angiogenic agents is a promising strategy to achieve persistent vascular shutdown by preventing reformation and reperfusion of photocoagulated blood vessels. Integration of LSI into the clinical workflow may lead to surgical image guidance that maximizes acute photocoagulation, is expected to improve PWS therapeutic outcome. Continued integration of noninvasive optical imaging technologies and biochemical analysis collectively are expected to lead to more robust treatment strategies.

Comparison of the fractional CO2 laser and the combined use of a pulsed dye laser with fractional CO2 laser in striae alba treatment

BACKGROUND

No ideal treatment has been established for Striae distensae (SD), particularly in the late phase (Striae Alba (SA)). Various types of lasers have been recently proposed as treatment options for SD. This study aims to compare the clinical efficacy of a fractional CO2 laser as well as a combination of fractional CO2 laser and Pulsed dye Laser (PDL) in the treatment of SA.

MATERIALS AND METHODS

Eighty-eight SA lesions in three female patients were included. Lesions on each half of the body were randomly enrolled in each group. Group 1 (n = 44) were treated by Fractional CO2 laser resurfacing and group 2 (n = 44) by a combination of PDL and Fractional CO2 laser, alternately. Digital Photographs were taken and the surface area of each lesion was measured digitally (using the PictZar Digital Planimetry Software) at the baseline and four weeks after treatment. The clinical improvement was assessed by comparison of the pre- and post-treatment photos and the participants' views about their degree of improvement, using a 10-point verbal analog scale (VAS).

RESULTS

The mean surface area decreased significantly in both groups after treatment. The mean difference between the pre- and post-treatment surface area was 0.62 ± 053 for group 2 and 0.41 ± 0.43 for group 1 (P-value = 0.03). Mean VAS and dermatologist assessed improvement scale in group 2 (6.68 ± 0.77 and 2.2 ± 0.76 respectively) were significantly higher than those in group 1 (5.45 ± 0.90 and 1.8±0.72 respectively, P-value <0.001 and 0.04 respectively).

CONCLUSION

The combination of PDL and fractional CO2 laser was more effective than fractional CO2 laser alone and could be suggested as a clinical option in the treatment of SA.

Effects of low-level laser therapy on wound healing

OBJECTIVE: To gather and clarify the actual effects of low-level laser therapy on wound healing and its most effective ways of application in human and veterinary medicine.METHODS: We searched original articles published in journals between the years 2000 and 2011, in Spanish, English, French and Portuguese languages, belonging to the following databases: Lilacs, Medline, PubMed and Bireme; Tey should contain the methodological description of the experimental design and parameters used.RESULTS: doses ranging from 3 to 6 J/cm2 appear to be more effective and doses 10 above J/cm2 are associated with deleterious effects. The wavelengths ranging from 632.8 to 1000 nm remain as those that provide more satisfactory results in the wound healing process.CONCLUSION: Low-level laser can be safely applied to accelerate the resolution of cutaneous wounds, although this fact is closely related to the election of parameters such as dose, time of exposure and wavelength.

Preclinical in vivo evaluation of NPe6-mediated photodynamic therapy on normal vasculature

BACKGROUND AND OBJECTIVE

Current treatments of port-wine stain birthmarks typically involve use of a pulsed dye laser (PDL) combined with cooling of the skin. Currently, PDL therapy protocols result in varied success, as some patients experience complete blanching, while others do not. Over the past decade, we have studied the use of photodynamic therapy (PDT) as either a replacement or adjuvant treatment option to photocoagulate both small and large vasculature. The objective of the current study was to evaluate a PDT protocol that involves use of an alternate intravascular photosensitizer mono-L-aspartylchlorin-e6 (NPe6) activated by an array of low-cost light emitting diodes.

STUDY DESIGN/MATERIALS AND METHODS

To monitor the microvasculature, a dorsal window chamber model was installed on 22 adult male mice. The light source consisted of a custom-built LED array that emitted 10 W at a center wavelength of 664 nm (FWHM = 20 nm). The light source was positioned at a fixed distance from the window chamber to achieve a fixed irradiance of 127 mW/cm(2). A retroorbital injection of NPe6 (5 mg/kg) was performed to deliver the drug into the bloodstream. Laser irradiation was initiated immediately after injection. To monitor blood-flow dynamics in response to PDT, we used laser speckle imaging. We employed a dose-response experimental design to evaluate the efficacy of NPe6-mediated PDT.

RESULTS

We observed three general hemodynamic responses to PDT: (1) At low radiant exposures, we did not observe any persistent vascular shutdown; (2) at intermediate radiant exposures, we observed an acute decrease in blood flow followed by gradual restoration of blood flow over the 7-day monitoring period; and (3) at high radiant exposures, we observed acute vascular shutdown that persisted during the entire 7-day monitoring period. Dose-response analysis enabled identification of 85 J/cm(2) as a characteristic radiant exposure required to achieve persistent vascular shutdown at Day 7 following PDT.

CONCLUSION

The experimental data suggest that NPe6-mediated PDT can achieve persistent vascular shutdown of normal microvasculature.

Surface layer-preserving photodynamic therapy (SPPDT) in a subcutaneous mouse model of lung cancer

BACKGROUND AND OBJECTIVES

Photodynamic therapy (PDT) may be a less invasive treatment for lung cancer. Our newly developed surface layer-preserving PDT (SPPDT) technique enables us to irradiate deep tumor while preserving the overlying tissue. The aim of this basic study was to verify that the SPPDT technique might be applied to lung cancer.

STUDY DESIGN/MATERIALS AND METHODS

PDT with talaporfin sodium was performed using a pulsed laser with different pulse dose rates (PDRs, 2.5-20.0 mJ/cm(2) /pulse) in a mouse model of subcutaneous tumor. To mimic the tracheal wall structure and a thoracic tumor in the tracheobronchus, we also made a mouse model in which a piece of swine cartilage was placed between the dermis and the tumor, and PDT was carried out 2 weeks after implantation. In both experiments, the tissue samples were collected 48 hours after PDT and evaluated microscopically.

RESULTS

SPPDT using a high-PDR laser damaged the underlying tissue but left the superficial tissue intact in the mouse subcutaneous tumor model. In SPPDT, a higher PDR produced a thicker layer of intact superficial tissue than a lower PDR, while a lower PDR produced a deeper layer of damaged tissue than a higher PDR. SPPDT was also able to preserve the superficial tissue and to damage the tumor tissue beneath the cartilage implant.

CONCLUSION

SPPDT was able to damage tumor beneath the superficial normal tissue layer, which included tracheal cartilage in the mouse model. The thickness control of SPPDT was provided by controlling laser pulse intensity. SPPDT is a new technology, whose future potential is unknown. The initial clinical application of this technology could be endoscopic treatment (e.g., palliative therapy of thoracic malignancies via bronchoscopy).

Photocoagulation of dermal blood vessels with multiple laser pulses in an in vivo microvascular model

BACKGROUND/OBJECTIVES

Current laser therapy of port wine stain (PWS) birthmarks with a single laser pulse (SLP) does not produce complete lesion removal in the majority of patients. To improve PWS therapeutic efficacy, we evaluated the performance of an approach based on multiple laser pulses (MLP) to enhance blood vessel photocoagulation.

STUDY DESIGN

The hamster dorsal window chamber model was used. Radiant exposure (RE), pulse repetition rate (f(r)), total number of pulses (n(p)), and length of vessel irradiated were varied. Blood vessels in the window were irradiated with either SLP with RE of 4-7 J/cm(2) or MLP with RE per pulse of 1.4-5.0 J/cm(2), f(r) of 0.5-26.0 Hz, and n(p) of 2-5. The laser wavelength was 532 nm and pulse duration was 1 ms. Either a 2 mm vessel segment or entire vessel branch was irradiated. Digital photographs and laser speckle images of the window were recorded before and at specific time points after laser irradiation to monitor laser-induced blood vessel structural and functional changes, respectively.

RESULTS

We found that: (1) for a SLP approach, the RE required to induce blood vessel photocoagulation was 7 J/cm(2) as compared to only 2 J/cm(2) per pulse for the MLP approach; (2) for MLP, two pulses at a repetition rate of 5 Hz and a RE of 3 J/cm(2) can induce photocoagulation of more than 80% of irradiated blood vessel; and (3) irradiation of a longer segment of blood vessel resulted in lower reperfusion rate.

CONCLUSIONS

The MLP approach can induce blood vessel photocoagulation at much lower RE per pulse as compared to SLP. The 5 Hz f(r) and the need for two pulses are achievable with modern laser technology, which makes the MLP approach practical in the clinical management of PWS birthmarks.

Increasing the efficiency of photodynamic therapy by improved light delivery and oxygen supply using an anticoagulant in a solid tumor model

BACKGROUND AND OBJECTIVE

The main factors in photodynamic therapy (PDT) are: photosensitizer retention, photon absorption, and oxygen supply. Each factor has its unique set of problems that poses limitation to the treatment. Both light delivery and oxygen supply are significant bottlenecks in PDT. Vascular closure during PDT reduces oxygen supply to the targeted tissue. On the other hand, with the changes in blood perfusion, the tissue optical properties change, and result in variation in irradiation light transmission. For these reasons, it becomes very important to avoid blood coagulation and vascular closure during PDT.

STUDY DESIGN/MATERIALS AND METHODS

The efficiency of PDT combined with the anticoagulant heparin was studied in a BALB/c mouse model with subcutaneous EMT6 mammary carcinomas. Mice were randomized into three groups: control, PDT-only, and PDT with heparin. The photosensitizer Photofrin was used in our experiments. Light transmission, blood perfusion, and local production of reactive oxygen species (ROS) were monitored during the treatment. The corresponding histological examinations were performed to determine the thrombosis immediately after irradiation and to evaluate tumor necrosis 48 hours after the treatment.

RESULTS

The results clearly demonstrated that PDT combined with pre-administered heparin can significantly reduce thrombosis during light irradiation. The blood perfusion, oxygen supply, and light delivery are all improved. Improved tumor responses in the combined therapy, as shown with the histological examination and tumor growth assay, are clearly demonstrated and related to an increased local ROS production.

CONCLUSION

Transitory anticoagulation treatment significantly enhances the antitumor effect of PDT. It is mainly due to the improvement of the light delivery and oxygen supply in tumor, and ultimately the amount of ROS produced during PDT.

Longitudinal, multimodal functional imaging of microvascular response to photothermal therapy

Although studies have shown that photothermal therapy can coagulate selectively abnormal vasculature, the ability of this method to achieve consistent, complete removal of the vasculature is questionable. We present the use of multimodal, wide-field functional imaging to study, in greater detail, the biological response to selective laser injury. Specifically, a single-platform instrument capable of coregistered fluorescence imaging and laser speckle imaging was utilized to monitor vascular endothelial growth factor gene expression and blood flow, respectively, in a transgenic rodent model. Collectively, the longitudinal, in vivo data collected with our instrument suggest that the biological response to selective laser injury involves early-stage redistribution of blood flow, followed by increased vascular endothelial growth factor promoter activity to stimulate pro-angiogenic events.

Long-term blood vessel removal with combined laser and topical rapamycin antiangiogenic therapy: implications for effective port wine stain treatment

BACKGROUND AND OBJECTIVES

Complete blanching of port wine stain (PWS) birthmarks after laser therapy is rarely achieved for most patients. We postulate that the low therapeutic efficacy or treatment failure is caused by regeneration and revascularization of photocoagulated blood vessels due to angiogenesis associated with the skin's normal wound healing response. Rapamycin (RPM), an antiangiogenic agent, has been demonstrated to inhibit growth of pathological blood vessels. Our objectives were to (1) investigate whether topical RPM can inhibit reperfusion of photocoagulated blood vessels in an animal model and (2) determine the effective RPM concentration required to achieve this objective.

STUDY DESIGN/MATERIALS AND METHODS

For both laser-only and combined laser and RPM treated animals, blood vessels in the dorsal window chambers implanted on golden Syrian hamsters were photocoagulated with laser pulses. Structural and flow dynamics of blood vessels were documented with color digital photography and laser speckle imaging to evaluate photocoagulation and reperfusion. For the combined treatment group, topical RPM was applied to the epidermal side of the window daily for 14 days after laser exposure.

RESULTS

In the laser-only group, 23 out of 24 photocoagulated blood vessels reperfused within 5-14 days. In the combined treatment group with different RPM formulae and concentrations, the overall reperfusion rate of 36% was much lower as compared to the laser-only group. We also found that the reperfusion rate was not linearly proportional to the RPM concentration.

CONCLUSIONS

With topical RPM application, the frequency of vessel reperfusion was considerably reduced, which implies that combined light and topical antiangiogenic therapy might be a promising approach to improve the treatment efficacy of PWS birthmarks.

An update on lasers in children

PURPOSE OF REVIEW

A variety of new indications for laser treatment have been raised in the dermatology field recently. They offer significant opportunities to manage a large spectrum of conditions in the pediatric population. Therefore, it is necessary to know the current trends and limitations of their use for the treatment of pigmented and vascular lesions.

RECENT FINDINGS

The pulsed dye laser for port wine stain treatment remains the gold standard. However, pulsed dye laser-resistant port wine stain constitutes a difficult management problem. New therapeutic modalities such as photodynamic therapy and the application of different topical angiogenesis inhibitors promise better results in avoiding port wine stain redarkening. The potential systemic effects also require further study. Traditionally, the Q-switched pigmented laser has been used for pigmented lesions. However, the 1550 nm wavelength erbium-doped fiber laser could be a new modality of treatment for Becker's nevus.

SUMMARY

Since the development of the first laser in 1960, dermatology and dermatologic surgery have rapidly evolved over the last two decades, thanks to the numerous technological and scientific acquisitions focused on improvement in the treatment of skin conditions. A large spectrum of vascular and pigmented lesions and other conditions such as chronic inflammatory skin diseases, such as psoriasis and eczema, keloids and hypertrichosis, are now managed safely with laser treatment.