Photothermolysis of blood vessels using indocyanine green and pulsed diode laser irradiation in the dorsal skinfold chamber model

Evaluating the efficacy of photodynamic therapy with indocyanine green in the treatment of keloid

BACKGROUND

This study aimed to evaluate the efficacy of photodynamic therapy (PDT) with topical indocyanine green (ICG) in the treatment of keloid lesions.

METHODS

In this pilot study, fifteen keloids (6 lesions on the sternal area, 3 on the shoulders, 2 on the abdomen, 2 on the legs, and 2 on the forearms) were selected. To enhance drug penetration, pretreatment with CO2 laser was performed. Then Lesions were covered with 0.2% transfersomal ICG gel with 1mm thickness and occluded with light-proof plastic nylon for 2 hours. Afterward, it was wiped off and underwent photodynamic therapy with source LumaCare with 730 nm probe and fluence of 23 J/cm2 every week for 6 sessions. Patients were also assessed 6 and 12 weeks after the treatment for any recurrences. The Patient and Observer Scar Assessment Scale (POSAS) was used to evaluate the scars.

RESULTS

The mean POSAS score significantly reduced by 23.69% from 46.86 at baseline to 35.76 at the 6^th treatment session (P< 0.001). The mean scores of patient and observer overall opinion significantly decreased by 16.35% (P< 0.001) and 12.31 % (P= 0.001) respectively. No side effects were observed during treatment and after 3 months of follow-ups. After discontinuation of therapy, the mean score of POSAS significantly increased by 13.77% to 40.80. (P= 0.001) CONCLUSION: : According to our study, ICG-PDT is an effective and safe treatment for keloid. However, due to the recurrence following discontinuation of treatment, further studies are needed.

Potential of Cyanine Derived Dyes in Photodynamic Therapy

Photodynamic therapy (PDT) is a method of cancer treatment that leads to the disintegration of cancer cells and has developed significantly in recent years. The clinically used photosensitizers are primarily porphyrin, which absorbs light in the red spectrum and their absorbance maxima are relatively short. This review presents group of compounds and their derivatives that are considered to be potential photosensitizers in PDT. Cyanine dyes are compounds that typically absorb light in the visible to near-infrared-I (NIR-I) spectrum range (750-900 nm). This meta-analysis comprises the current studies on cyanine dye derivatives, such as indocyanine green (so far used solely as a diagnostic agent), heptamethine and pentamethine dyes, squaraine dyes, merocyanines and phthalocyanines. The wide array of the cyanine derivatives arises from their structural modifications (e.g., halogenation, incorporation of metal atoms or organic structures, or synthesis of lactosomes, emulsions or conjugation). All the following modifications aim to increase solubility in aqueous media, enhance phototoxicity, and decrease photobleaching. In addition, the changes introduce new features like pH-sensitivity. The cyanine dyes involved in photodynamic reactions could be incorporated into sets of PDT agents.

Irradiance, Photofrin® Dose and Initial Tumor Volume are Key Predictors of Response to Interstitial Photodynamic Therapy of Locally Advanced Cancers in Translational Models

The objective of the present study was to develop a predictive model for Photofrin® -mediated interstitial photodynamic therapy (I-PDT) of locally advanced tumors. Our finite element method was used to simulate 630-nm intratumoral irradiance and fluence for C3H mice and New Zealand White rabbits bearing large squamous cell carcinomas. Animals were treated with light only or I-PDT using the same light settings. I-PDT was administered with Photofrin® at 5.0 or 6.6 mg kg-1 , 24 h drug-light interval. The simulated threshold fluence was fixed at 45 J cm-2 while the simulated threshold irradiance varied, intratumorally. No cures were obtained in the mice treated with a threshold irradiance of 5.4 mW cm-2 . However, 20-90% of the mice were cured when the threshold irradiances were ≥8.6 mW cm-2 . In the rabbits treated with I-PDT, 13 of the 14 VX2 tumors showed either local control or were cured when threshold irradiances were ≥15.3 mW cm-2 and fluence was 45 J cm-2 . No tumor growth delay was observed in VX2 treated with light only (n = 3). In the mouse studies, there was a high probability (92.7%) of predicting cure when the initial tumor volume was below the median (493.9 mm3 ) and I-PDT was administered with a threshold intratumoral irradiance ≥8.6 mW cm-2 .

A new finite element approach for near real-time simulation of light propagation in locally advanced head and neck tumors

Background and Objectives

Several clinical studies suggest that interstitial photodynamic therapy (I‐PDT) may benefit patients with locally advanced head and neck cancer (LAHNC). For I‐PDT, the therapeutic light is delivered through optical fibers inserted into the target tumor. The complex anatomy of the head and neck requires careful planning of fiber insertions. Often the fibers' location and tumor optical properties may vary from the original plan therefore pretreatment planning needs near real‐time updating to account for any changes. The purpose of this work was to develop a finite element analysis (FEA) approach for near real‐time simulation of light propagation in LAHNC.

Methods

Our previously developed FEA for modeling light propagation in skin tissue was modified to simulate light propagation from interstitial optical fibers. The modified model was validated by comparing the calculations with measurements in a phantom mimicking tumor optical properties. We investigated the impact of mesh element size and growth rate on the computation time, and defined optimal settings for the FEA. We demonstrated how the optimized FEA can be used for simulating light propagation in two cases of LAHNC amenable to I‐PDT, as proof‐of‐concept.

Results

The modified FEA was in agreement with the measurements (P = 0.0271). The optimal maximum mesh size and growth rate were 0.005–0.02 m and 2–2.5 m/m, respectively. Using these settings the computation time for simulating light propagation in LAHNC was reduced from 25.9 to 3.7 minutes in one case, and 10.1 to 4 minutes in another case. There were minor differences (1.62%, 1.13%) between the radiant exposures calculated with either mesh in both cases.

Conclusions

Our FEA approach can be used to model light propagation from diffused optical fibers in complex heterogeneous geometries representing LAHNC. There is a range of maximum element size (MES) and maximum element growth rate (MEGR) that can be used to minimize the computation time of the FEA to 4 minutes. Lasers Surg. Med. 47:60–67, 2015. © 2015 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Hyperthermia-enhanced indocyanine green delivery for laser-induced thermal ablation of carcinomas

PURPOSE

Intravenous administration of indocyanine green (ICG) dye can effectively convert near-infrared (NIR) laser light into heat and enhance thermal injury of blood vessels; however, there is no selective uptake of ICG by the tumour compared to the other tissues, which impacts the therapeutic ratio of this strategy unless uptake can be selectively increased in tumour tissue. Here we investigated the use of local hyperthermia prior to intravenous ICG administration to enhance ICG uptake in tumour tissue, thereby enhancing laser thermal ablation of solid tumours.

METHODS

Murine SCK breast or SCCVII head and neck tumours were treated with a 755-nm laser light either alone or with prior intravenous administration of 4 mg/kg ICG and/or local tumour hyperthermia at 42.5 °C for 60 min. Retention of ICG was quantified using a NIR animal imaging system. Treatment effects were assessed by growth delay and histology.

RESULTS

ICG accumulation in the heated tumours was 1.23-fold greater on average compared to non-heated tumours, in both models. In SCK tumours, animals receiving either laser irradiation alone or in conjunction with ICG had a 1.86- or 3.91-fold increase in tumour growth delay, respectively. The addition of local hyperthermia before ICG injection resulted in complete regression of SCK tumours. Uptake of ICG increased in SCCVII tumours; however, little change in tumour growth delay was observed.

CONCLUSION

Using local hyperthermia may improve the delivery of ICG to the tumour and thereby increase the extent of laser thermal ablation of smaller superficial malignancies that can be effectively exposed to laser therapy.

Therapeutic effect of the treatment for colorectal cancer with adenoviral vectors mediated estrogen receptor β gene therapy combined with thermotherapy

INTRODUCTION

Our preliminary study on repressing colorectal tumors by recombinant adenoviruses (Ads) delivering the human ERβ gene (Ad-ERβ) has achieved positive result.

METHODS

In this study, hydrophobic fluorescent dyes ICG-Der-01 was entrapped into the N-succinyl-N'-octyl chitosan (SOC) micelles to form the near infrared absorbing dyes SOC-ICG-Der-01 and SOC-ICG-Der-01 mediated near infrared laser (SOC-ICG-Der-01/NIR) thermotherapy was combined with Ad-ERβ gene therapy to regress colon cancer in vivo.

RESULTS

Firstly, the antitumor efficacies of SOC-ICG-Der-01/NIR thermotherapy were investigated on S180 ascites tumor-bearing mice. Results indicated that, the average tumor volume of SOC-ICG-Der-01/NIR group was the smallest among the three treatment groups. Then, thermotherapy with SOC-ICG-Der-01/NIR combined with Ad-ERβ gene therapy to treat HCT-116 colon cancer xenograft model was investigated. Further results demonstrated that, SOC-ICG-Der-01/NIR thermotherapy showed the significantly inhibitory efficiency compared with control group and Ad-ERβ enhanced the therapeutic effect of SOC-ICG-Der-01/NIR.

CONCLUSION

These findings demonstrated that combined administration of Ad-ERβ with SOC-ICG-Der-01/NIR thermotherapy represents a promising colon cancer therapeutic strategy.

Pulsed dye laser-resistant port-wine stains: mechanisms of resistance and implications for treatment

Port-wine stains (PWS) are among the most common congenital vascular malformations. Unlike capillary haemangiomas, these lesions do not involute spontaneously but rather become progressively more disfiguring as the patient ages. While benign in nature, the cosmetic deformity and attendant psychological and emotional distress prompt the majority of those afflicted to seek treatment. The pulsed dye laser (PDL) has long been considered the treatment of choice for these vascular lesions; however, very few patients achieve total clearance with PDL therapy and a significant number of lesions fail to respond at all. In order to address these recalcitrant cases, the mechanisms that contribute to treatment resistance must be understood and novel laser and light therapies must be employed. This review will address what is currently known about lesion-specific characteristics of PDL-resistant PWS as well as discuss current and future treatment options.

Indocyanine green-augmented diode laser treatment of port-wine stains: clinical and histological evidence for a new treatment option from a randomized controlled trial

BACKGROUND

Complete clearance of port-wine stains (PWS) is difficult to achieve, mainly because of the resistance of small blood vessels to laser irradiation. Indocyanine green (ICG)-augmented diode laser treatment (ICG+DL) may overcome this problem.

OBJECTIVES

To evaluate the feasibility of ICG+DL therapy of PWS and to compare the safety and efficacy of ICG+DL with the standard treatment, flashlamp-pumped pulsed dye laser (FPDL).

METHODS

In a prospective randomized controlled clinical study, 31 patients with PWS were treated with FPDL (λ(em)=585 nm, 6 J cm(-2) , 0.45 ms pulse duration) and ICG+DL (λ(em)=810 nm, 20-50 J cm(-2) , 10-25 ms pulse duration, ICG-concentration: 2 mg kg(-1) body weight) in a split-face modus in one single treatment setting that included histological examination (haematoxylin and eosin, CD34). Two blinded investigators and the patients assessed clearance rate, cosmetic appearance and side-effects up to 3 months after treatment.

RESULTS

ICG+DL therapy induced photocoagulation of medium and large blood vessels (>20 μm diameter) but not of small blood vessels. According to the investigators' assessment, clearance rates and cosmetic appearance were better after ICG+DL therapy than after FPDL treatment (P=0.114, P=0.291, respectively), although not up to a statistically significant level, whereas patients considered these parameters superior (P=0.003, P=0.006, respectively). On a 10-point scale indicating pain during treatment, patients rated ICG+DL to be more painful (5.81 ± 2.12) than FPDL treatment (1.61 ± 1.84).

CONCLUSION

ICG+DL represents a new and promising treatment modality for PWS, but laser parameters and ICG concentration need to be further optimized.

[New developments in laser therapy]

Based on the theory of stimulated emission of radiation that was proposed by Albert Einstein in 1916, the first lasers were developed in the 1960s. The first clinical use of laser technology in a German university took place in 1978 in the Department of Dermatology of the Ludwig-Maximilian-University in Munich under the guidance of the former director, Prof. Dr. med. Dr. h.c. mult. Otto Braun-Falco. In the following years, laser technology developed rapidly. Today laser technology is a widely used interdisciplinary therapeutic procedure that has deep clinical and scientific roots in dermatology. There are many conditions in both classic and aesthetic dermatology that are routinely - and sometimes exclusively - treated with lasers. Here we review recent developments in laser medicine. There seems to be a trend to combination procedures. To enhance efficacy, different laser systems are together or lasers are combined with specific topical medications.

Indocyanine green enhanced near-infrared laser treatment of murine mammary carcinoma

It is well accepted that near-infrared (NIR) lasers are appropriate to ablate benign lesions and induce irreversible thermal injury in deeply seated blood vessels. At this wavelength, the laser light penetrates deep (3-5 mm) into the skin. However, many researchers have reported noticeable pain, extending from mild to severe, during and immediately after NIR laser treatment. Intravenous administration of an exogenous chromophore [indocyanine green (ICG), dye] can effectively convert NIR laser light into heat. In this approach, the presence of ICG has shown to enhance thermal injury of blood vessels in the treatment of healthy tissues. However, the effectiveness of thermal injury on the regression of cutaneous carcinomas during ICG/NIR laser therapy has not been assessed. The purpose of our study was to evaluate the potential benefit of using ICG/NIR laser therapy to regress superficial carcinoma with thermal injury. Two groups of A/J mice with subcutaneous mammary adenocarcinoma tumors (7-9 mm) were irradiated with a 808-nm NIR laser preceded by tail vein injection of ICG dye or sterile saline. Histological evaluation of the subcutaneous tissue revealed minor thermal damage and necrosis in the laser/saline group and substantial damage (up to 100% necrosis) in the laser/ICG group. The laser/ICG-treated group showed a steady reduction in tumor volume compared to the laser/saline group: 48% by day 5 (p = 0.045) and 69-70% by days 8, 9 and 10 (p values 0.0005 or less). The vascular-targeted ICG-NIR laser therapy appears to have potential for treating superficial tumors.

Effect of polyethylene glycol coatings on uptake of indocyanine green loaded nanocapsules by human spleen macrophages in vitro

Near-infrared (NIR) optically active nanoparticles are promising exogenous chromophores for applications in medical imaging and phototherapy. Since nanoparticles can be rapidly eliminated from the body by cells of the reticuloendothelial system, a thriving strategy to increase their blood circulation time is through surface modification with polyethylene glycol (PEG). We constructed polymeric nanocapsules loaded with indocyanine green (ICG), an FDA-approved NIR dye, and coated with aldehyde-terminated PEG. Using optical absorbance spectroscopy and flow cytometry, we investigated the effect of PEG coating and molecular weight (MW) of PEG [5000 and 30,000 Daltons (Da)] on the phagocytic content of human spleen macrophages incubated with ICG-containing nanocapsules (ICG-NCs) between 15 to 360 min. Our results indicate that surface coating with PEG is an effective method to reduce the phagocytic content of ICG-NCs within macrophages for at least up to 360 min of incubation time. Coating the surface of ICG-NCs with the low MW PEG results in lower phagocytic content of ICG-NCs within macrophages for at least up to 60 min of incubation time as compared to ICG-NCs coated with the high MW PEG. Surface coating of ICG-NCs with PEG is a promising approach to prolong vasculature circulation time of ICG for NIR imaging and phototherapeutic applications.

Biodistribution of encapsulated indocyanine green in healthy mice

Indocyanine green (ICG) is a fluorescent probe used in various optically mediated diagnostic and therapeutic applications. However, utility of ICG remains limited by its unstable optical properties and nonspecific localization. We have encapsulated ICG within electrostatically assembled mesocapsules (MCs) to explore its potential for targeted optical imaging and therapy. In this study, we investigate how the surface coating and size of the MCs influences ICG's biodistribution in vivo. ICG was administered intravenously to Swiss Webster mice as a free solution or encapsulated within either 100 nm diameter MCs coated with dextran; 500 nm diameter MCs coated with dextran; or 100 nm diameter MCs coated with 10 nm ferromagnetic iron oxide nanoparticles, themselves coated with polyethylene glycol. ICG was extracted from harvested blood and organs at various times and its amount quantified with fluorescence measurements. MCs containing ICG accumulated in organs of the reticuloendothelial system, namely, the liver and spleen, as well as the lungs. The circulation kinetics of ICG appeared unaffected by encapsulation; however, the deposition within organs other than the liver suggests a different biodistribution mechanism. Results suggest that the capsules' coating influences their biodistribution to a greater extent than their size. The MC encapsulation system allows for delivery of ICG to organs other than the liver, enabling the potential development of new optical imaging and therapeutic strategies.

Intravital microscopy of tumor angiogenesis and regression in the dorsal skin fold chamber: mechanistic insights and preclinical testing of therapeutic strategies

Tumor angiogenesis is a major step in tumor progression to clinically symptomatic cancer and thus a potential target for cancer therapy. It is essential to understand the fundamental mechanisms of the angiogenic processes to provide a rational for testing inhibitory strategies for cancer treatment. The dorsal skin fold chamber provides a suitable (chronic) model for intravital microscopy to monitor the same tumor in time-lapse imaging series and in real-time functional analysis e.g., of blood flow. Adaptation of this model to several rodent species and tumor types has led to numerous physical and drug based therapy options. With modification of implantation techniques, motility and invasion of individual cells can be visualized, in addition to angiogenesis and microcirculation. Modern fluorescent techniques such as ex vivo labelling of specific cell populations and the introduction of stably fluorescent protein expressing cell lines further enhance the suitability of this technique. In addition, laser scanning and multiphoton microscopy in combination with genetically altered mouse strains and cell lines are making the DCSF even more attractive for mechanistic and interventional studies in cancer research. Here we review the preparation as well as the applications of the DCSF in tumor angiogenesis.

Laser-induced (endo)vascular photothermal effects studied by combined brightfield and fluorescence microscopy in hamster dorsal skin fold venules

The putative features of the (endo)vascular photothermal response, characterized by laser-induced thermal denaturation of blood and vessel wall constituents, have been elucidated individually, but not simultaneously in dynamic, isolated in vivo systems. A hamster dorsal skin fold model in combination with brightfield/fluorescence intravital microscopy was used to examine the effect of laser pulse duration and blood flow velocity on the size of the thermal coagulum, its attachment behavior, and laser-mediated vasomotion. The size of the coagulum and the extent of vasoconstriction and latent vasodilation were proportional to the laser pulse duration, but pulse duration had no effect on coagulum attachment/dislodgement. Blood flow velocity exhibited no significant effect on the studied parameters. The (endo)vascular photothermal response is governed predominantly by laser energy deposition and to a marginal extent by blood flow velocity.