The effect of light fractionation with a 2-h dark interval on the efficacy of topical hexyl-aminolevulinate photodynamic therapy in normal mouse skin

Middelburg, Tom A.; Bruijn, Henriëtte S. de; Heuvel, A. van der Ploeg-van den; Neumann, H. A. M.; Robinson, Dominic J.

doi:10.1016/j.pdpdt.2013.09.002

Cited by 8 publications

(9 citation statements)

References 31 publications

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“…Although twofold MAL-PDT has not yet been studied in humans, previous studies using mouse models did not show a favourable response to fractionation in MAL-PDT. 33,34 In conclusion, our findings suggest a trend towards better efficacy for twofold ALA-PDT compared with conventional MAL-PDT for the treatment of sBCC, although the difference is not statistically significant. However, the twofold ALA-PDT regimen entails a higher risk of pain and side-effects.…”

Section: Discussionmentioning

confidence: 53%

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Treatment of superficial basal cell carcinoma by topical photodynamic therapy with fractionated 5-aminolaevulinic acid 20% vs. two-stage topical methyl aminolaevulinate: results of a randomized controlled trial

et al. 2018

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Section: Discussionmentioning

confidence: 53%

“…For future studies, it would be interesting to compare the twofold fractionated ALA‐PDT regimen with a comparable fractionated MAL‐PDT regimen. Although twofold MAL‐PDT has not yet been studied in humans, previous studies using mouse models did not show a favourable response to fractionation in MAL‐PDT …”

Section: Discussionmentioning

confidence: 99%

Treatment of superficial basal cell carcinoma by topical photodynamic therapy with fractionated 5-aminolaevulinic acid 20% vs. two-stage topical methyl aminolaevulinate: results of a randomized controlled trial

et al. 2018

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“…It improves the preclinical and clinical response of ALA-PDT, but not of MAL-PDT in mouse skin (16,18). Recent data suggest that light fractionation is also beneficial for HAL-PDT (19). We postulate that these differences in response to light fractionation are related to differences in vascular sensitization between the three porphyrin precursors.…”

Section: Introductionmentioning

confidence: 90%

Topical Photodynamic Therapy Using Different Porphyrin Precursors Leads to Differences in Vascular Photosensitization and Vascular Damage in Normal Mouse Skin

Middelburg

Vijlder

Bruijn

et al. 2014

Photochem & Photobiology

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Different distributions of hexyl aminolevulinate (HAL), aminolevulinic acid (ALA) and methyl aminolevulinate (MAL) in the superficial vasculature are not well studied but they are hypothesized to play an important role in topical photodynamic therapy (PDT). The colocalization of fluorescent CD31 and protoporphyrin IX (PpIX) was calculated using confocal microscopy of mouse skin sections to investigate the vascular distribution after topical application. Vascular damage leads to disruption of the normal endothelial adherens junction complex, of which CD144 is an integral component. Therefore, normal CD31 combined with loss of normal fluorescent CD144 staining was visually scored to assess vascular damage. Both the vascular PpIX concentration and the vascular damage were highest for HAL, then ALA and then MAL. Vascular damage in MAL was not different from normal contralateral control skin. This pattern is consistent with literature data on vasoconstriction after PDT, and with the hypothesis that the vasculature plays a role in light fractionation that increases efficacy for HAL and ALA-PDT but not for MAL. These findings indicate that endothelial cells of superficial blood vessels synthesize biologically relevant PpIX concentrations, leading to vascular damage. Such vascular effects are expected to influence the oxygenation of tissue after PDT which can be important for treatment efficacy.

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“…Their results indicate that intermittent and repeated a-PDT allowed improved inactivation of the bacilli compared to continuous light exposure [12]. In dermatology, light fractionation was also shown to lower the rate of photobleaching of the photosensitizer upon light irradiation and was therefore recommended to increase the efficacy of aminolevulinic acid (ALA) photodynamic therapy [13].…”

Section: Introductionmentioning

confidence: 99%

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

Marinic

Manoil

Filieri

et al. 2015

Photodiagnosis and Photodynamic Therapy

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Background: In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating Enterococcus faecalis biofilms, in vitro. Methods: E. faecalis biofilms formed on hydroxyapatite disks were incubated with eosin Y (10-80 M), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40 min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light/photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bacterial Viability kit and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (˛= 0.05). * Corresponding author. Results:The viability of E. faecalis biofilms exposed to 10 M eosin Y, was significantly reduced compared to controls (light only-eosin Y only). After a second exposure to blue light-activated eosin Y, viability significantly decreased from 58% to 12% whereas 6.5% of the bacterial biofilm remained live after a third exposure (p < 0.05). Only 3.5% of the bacterial population survived after the fourth exposure. Conclusions:The results of this study indicate that blue light-activated eosin Y can photoinactivate E. faecalis biofilms grown on hydroxyapatite disks. Also, repeated exposures to blue light-activated eosin Y were shown to significantly improve efficacy. Further studies seem warranted to optimize the antibacterial activity of blue light-activated eosin Y on major oral pathogens.

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The effect of light fractionation with a 2-h dark interval on the efficacy of topical hexyl-aminolevulinate photodynamic therapy in normal mouse skin

Cited by 8 publications

References 31 publications

Treatment of superficial basal cell carcinoma by topical photodynamic therapy with fractionated 5-aminolaevulinic acid 20% vs. two-stage topical methyl aminolaevulinate: results of a randomized controlled trial

Treatment of superficial basal cell carcinoma by topical photodynamic therapy with fractionated 5-aminolaevulinic acid 20% vs. two-stage topical methyl aminolaevulinate: results of a randomized controlled trial

Topical Photodynamic Therapy Using Different Porphyrin Precursors Leads to Differences in Vascular Photosensitization and Vascular Damage in Normal Mouse Skin

Repeated exposures to blue light-activated eosin Y enhance inactivation of E. faecalis biofilms, in vitro

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