Preclinical evaluation of benzoporphyrin derivative combined with a light-emitting diode array for photodynamic therapy of brain tumors

In-Vitro Use of Verteporfin for Photodynamic Therapy in Glioblastoma

BACKGROUND

Stummer et al. established fluorescence-guided surgery (FGS) for glioblastoma (GBM) using 5-aminolevulinic acid (5-ALA). Its metabolite, protoporphyrin IX (PPIX), is also a photosensitizer and can be used for photodynamic therapy (PDT) using a laser beam of 635 nm. The porphyrin derivate verteporfin (VP) was discovered to have properties to penetrate the brain, pharmacologically target glioma cells, and is approved for PDT of choroidal neovascularization in wet age-related macular degeneration at 689 nm.

OBJECTIVE

To elucidate whether GBM cell lines are susceptible to PDT with second-generation photosensitizer VP.

METHODS

Human glioma cell lines LN229, HSR-GBM1, and a low-passage patient-derived GBM cell line P1 were treated with variable concentrations of VP for 24 h, followed by PDT at 689 nm using a diode laser light. Cell viability was measured using the MTT assay and VP uptake was measured using a desktop cytometer.

RESULTS

Significantly higher cell death following PDT with VP compared to VP treatment alone or no treatment was detected in all cell models (LN229, HSR-GBM1, P1). Flowcytometric measurements revealed a concentration-dependent cellular uptake of VP after 24 h incubation up to 99% at 10 µM (HSR-GBM1).

CONCLUSION

This study demonstrates that PDT with VP causes cell death in GBM cells at marginal concentrations. Additionally, red spectrum fluorescence was detected at therapeutic concentrations in all cell lines, validating the cellular uptake of VP in GBM cells. VP, therefore, is not only a potential drug for targeting GBM pharmacologically but can be used as an optical imaging dye in surgery and photosensitizer to make GBM susceptible to PDT.

Low-cost photodynamic therapy devices for global health settings: Characterization of battery-powered LED performance and smartphone imaging in 3D tumor models

A lack of access to effective cancer therapeutics in resource-limited settings is implicated in global cancer health disparities between developed and developing countries. Photodynamic therapy (PDT) is a light-based treatment modality that has exhibited safety and efficacy in the clinic using wavelengths and irradiances achievable with light-emitting diodes (LEDs) operated on battery power. Here we assess low-cost enabling technology to extend the clinical benefit of PDT to regions with little or no access to electricity or medical infrastructure. We demonstrate the efficacy of a device based on a 635 nm high-output LED powered by three AA disposable alkaline batteries, to achieve strong cytotoxic response in monolayer and 3D cultures of A431 squamous carcinoma cells following photosensitization by administering aminolevulinic acid (ALA) to induce the accumulation of protoporphyrin IX (PpIX). Here we characterize challenges of battery-operated device performance, including battery drain and voltage stability specifically over relevant PDT dose parameters. Further motivated by the well-established capacity of PDT photosensitizers to serve as tumour-selective fluorescence contrast agents, we demonstrate the capability of a consumer smartphone with low-cost add-ons to measure concentration-dependent PpIX fluorescence. This study lays the groundwork for the on-going development of image-guided ALA-PDT treatment technologies for global health applications.

Compared to purpurinimides, the pyropheophorbide containing an iodobenzyl group showed enhanced PDT efficacy and tumor imaging (124I-PET) ability

Two positional isomers of purpurinimide, 3-[1'-(3-iodobenzyloxyethyl)] purpurin-18-N-hexylimide methyl ester 4, in which the iodobenzyl group is present at the top half of the molecule (position-3), and a 3-(1'-hexyloxyethy)purpurin-18-N-(3-iodo-benzylimide)] methyl ester 5, where the iodobenzyl group is introduced at the bottom half (N-substitued cyclicimide) of the molecule, were derived from chlorophyll-a. The tumor uptake and phototherapeutic abilities of these isomers were compared with the pyropheophorbide analogue 1 (lead compound). These compounds were then converted into the corresponding 124I-labeled PET imaging agents with specific activity >1 Ci/micromol. Among the positional isomers 4 and 5, purpurinimide 5 showed enhanced imaging and therapeutic potential. However, the lead compound 1 derived from pyropheophorbide-a exhibited the best PET imaging and PDT efficacy. For investigating the overall lipophilicity of the molecule, the 3-O-hexyl ether group present at position-3 of purpurinimide 5 was replaced with a methyl ether substituent, and the resulting product 10 showed improved tumor uptake, but due to its significantly higher uptake in the liver, spleen, and other organs, a poor tumor contrast in whole-body tumor imaging was observed.

Synthesis of novel carboranylchlorins with dual application in boron neutron capture therapy (BNCT) and photodynamic therapy (PDT)

Total synthesis of carboranylchlorins 3 and 4, from readily available starting materials, are described and the molecular structures of two key intermediates are presented. Chlorins 3 and 4 show similar spectroscopic behavior but differ considerably in their solubility properties; whereas closo-carboranylchlorin 3 is completely insoluble in water, its nido derivative 4 has good water-solubility. Carboranylchlorin 3 absorbs in the red region of the optical spectrum (at lambda(max)=642 nm) six times more strongly than porphyrin 1, and displays a fluorescence emission band at lambda(max)=651 nm, upon excitation at 642 nm. The water-soluble carboranylchlorin 4 also displays intense absorption and emission bands at lambda(max)=642 and 651 nm, respectively, in ethanol solution. It is concluded that carboranylchlorins 3 and 4 have higher promise for the dual application in PDT and BNCT than do comparable porphyrins.

Applications of liposomes in ophthalmology

This review outlines the applications of liposomal formulations in ophthalmology. In ophthalmology, liposomes have been used to treat disorders of both the anterior and posterior segments. These include dry eyes, keratitis, corneal transplant rejection, uveitis, endophthalmitis, and proliferative vitreoretinopathy. Liposomes also have shown promise as vectors for genetic transfection and monoclonal antibody-directed vehicles. Furthermore, heat-activated liposomes have spurred research in focal laser and heat-induced release of liposomal drugs and dyes for selective drug delivery. These techniques have been useful in selective tumor and neovascular vessel occlusion, angiography, and retinal and choroidal blood-flow studies. Although verteporfin is the only liposomal drug currently approved for use in the eye, the benefits of liposomes will likely be applied widely in all treatment, diagnostic, and research aspects of ophthalmology in the future.

New light on the brain: The role of photosensitizing agents and laser light in the management of invasive intracranial tumors

Invasive intracranial tumors, particularly malignant gliomas, are very difficult to eradicate surgically and carry a dismal prognosis. The vast majority relapse locally indicating that their cure is dependent on radical and complete local excision. However, their ability to invade and hide among normal brain tissue, our inability to visualize and detect them, the low tolerance of brain tissue to ionizing radiation and the presence of the blood brain barrier are the main causes of our failure to eradicate them. Photodynamic detection with 100% specificity and more than 80% sensitivity offers an excellent chance of visualizing camouflaged tumor nests. Also, photodynamic therapy offers a very good chance of targeted destruction of the remaining tumor cells safely following surgical excision and may double the survival of patients harboring these awful tumors. More work needs to be done to refine this promising technology to exploit it to its full potential.

Effect of NASA light-emitting diode irradiation on molecular changes for wound healing in diabetic mice

OBJECTIVE

The purpose of this study was to assess the changes in gene expression of near-infrared light therapy in a model of impaired wound healing.

BACKGROUND DATA

Light-Emitting Diodes (LED), originally developed for NASA plant growth experiments in space, show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper we present the effects of LED treatment on wounds in a genetically diabetic mouse model.

MATERIALS AND METHODS

Polyvinyl acetal (PVA) sponges were subcutaneously implanted in the dorsum of BKS.Cg-m +/+ Lepr(db) mice. LED treatments were given once daily, and at the sacrifice day, the sponges, incision line and skin over the sponges were harvested and used for RNA extraction. The RNA was subsequently analyzed by cDNA array.

RESULTS

Our studies have revealed certain tissue regenerating genes that were significantly upregulated upon LED treatment when compared to the untreated sample. Integrins, laminin, gap junction proteins, and kinesin superfamily motor proteins are some of the genes involved during regeneration process. These are some of the genes that were identified upon gene array experiments with RNA isolated from sponges from the wound site in mouse with LED treatment.

CONCLUSION

We believe that the use of NASA light-emitting diodes (LED) for light therapy will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the Defense Advanced Research Projects Agency (DARPA) and NASA Marshall Space Flight Center-SBIR Program.

Photoreaction generating active oxygens of In(3+)-tetrakis(4-methylpyridyl)-porphine in the presence of albumins

The complex formation of In(3+)-tetrakis(4-N-methylpyridyl)-porphine (In-TMPyP) with albumin was studied by resonance Raman spectroscopy. Albumin coordinated to In(3+) through the -S(-) group(s). The photoreaction was investigated using the visible spectral change and In-TMPyP-thiourea complex was used as a model. It was demonstrated that the complex in a weak basic solution (pH 8.5) is excited by light and the excited complex converts oxygen to superoxide anion, which finally cleavages the porphine ring of In-TMPyP.

Effect of NASA light-emitting diode irradiation on wound healing

OBJECTIVE

The purpose of this study was to assess the effects of hyperbaric oxygen (HBO) and near-infrared light therapy on wound healing.

BACKGROUND DATA

Light-emitting diodes (LED), originally developed for NASA plant growth experiments in space show promise for delivering light deep into tissues of the body to promote wound healing and human tissue growth. In this paper, we review and present our new data of LED treatment on cells grown in culture, on ischemic and diabetic wounds in rat models, and on acute and chronic wounds in humans.

MATERIALS AND METHODS

In vitro and in vivo (animal and human) studies utilized a variety of LED wavelength, power intensity, and energy density parameters to begin to identify conditions for each biological tissue that are optimal for biostimulation.

RESULTS

LED produced in vitro increases of cell growth of 140-200% in mouse-derived fibroblasts, rat-derived osteoblasts, and rat-derived skeletal muscle cells, and increases in growth of 155-171% of normal human epithelial cells. Wound size decreased up to 36% in conjunction with HBO in ischemic rat models. LED produced improvement of greater than 40% in musculoskeletal training injuries in Navy SEAL team members, and decreased wound healing time in crew members aboard a U.S. Naval submarine. LED produced a 47% reduction in pain of children suffering from oral mucositis.

CONCLUSION

We believe that the use of NASA LED for light therapy alone, and in conjunction with hyperbaric oxygen, will greatly enhance the natural wound healing process, and more quickly return the patient to a preinjury/illness level of activity. This work is supported and managed through the NASA Marshall Space Flight Center-SBIR Program.

Optimal light dose for interstitial photodynamic therapy in treatment for malignant brain tumors

BACKGROUND AND OBJECTIVE

The primary goal was to determine the maximal tolerable light dose that can be administered to patients undergoing multifiber interstitial photodynamic therapy (PDT) of malignant brain tumors at a fixed dose of photosensitizer.

STUDY DESIGN/MATERIALS AND METHODS

Eighteen patients (12 glioblastomas, 5 anaplastic astrocytoma, and 1 malignant ependymoma) were included in this study. The total light dose delivered to the tumor was divided into three groups of six patients each: 1,500-3,700 J, 3,700-4,400 J, and 4,400-5,900 J.

RESULTS

Five patients (all glioblastomas) demonstrated postoperative permanent neurologic deficits. None of the patients in 1,500-3,700 J, two patients in 3,700-4,400 J, and three patients in 4,400-5,900 J had neurologic deficits. Glioblastomas recurred more often than anaplastic astrocytomas. Increasing the light dose did not make a difference in local/regional control of glioblastomas. Patients with anaplastic astrocytomas survived (mean, 493 days) longer than patients with glioblastomas (mean, 116.5 days) after PDT. Four patients had prolonged survival (more than a year) after PDT.

CONCLUSIONS

Increasing the total light dose delivered to the tumor increases the odds of having a permanent neurologic deficit but does not increase survival or time to tumor progression. There was no difference in local or marginal recurrence with increasing light dose. Recurrent anaplastic astrocytomas tend to do better than recurrent glioblastomas with PDT.