Photodynamic therapy for cutaneous proliferative vascular tumors in a mouse model

Effects of arginine-glycine-aspartic acid peptide-conjugated quantum dots-induced photodynamic therapy on pancreatic carcinoma in vivo

Quantum dots (QDs) conjugated with integrin antagonist arginine-glycine-aspartic acid (RGD) peptides (QDs-RGD) are novel nanomaterials with a unique optical property: a high molar extinction coefficient. Previously, we have shown that QDs-RGD demonstrate a photodynamic therapy (PDT) effect as new photosensitizers for the pancreatic cancer cell line SW1990 in vitro. Here, we investigate the application of QDs-RGD in mice bearing pancreatic tumors using PDT. To ensure that more photosensitizers accumulated in tumors, QDs-RGD were injected intratumorally. After selection of an adequate dosage for injection from analyses of biodistribution images captured by an IVIS system, PDT was initiated. Three groups were created according to different PDT procedures. In group 1, mice were injected with QDs-RGD intratumorally, and an optical fiber connected to a laser light was inserted directly into the tumor. Irradiation was sustained for 20 min with a laser light (630 nm) at 100 mW/cm2. In group 2, the laser optical fiber was placed around, and not inserted into, tumors. In group 3, PDT was conducted as in group 1 but without injection of QDs-RGD. After 28 days of observation, tumors on the back of mice in group 1 grew slowly (V/V0 =3.24±0.70) compared with the control groups, whose tumors grew quickly, and the mean V/V0 reached 6.08±0.50 (group 2) and 7.25±0.82 (group 3). Histology of tumor tissues showed more necrotic tissues, more inflammatory cells, and less vascular tissue in the PDT group than those in the control groups. These results suggest that QDs-RGD-mediated PDT, with illumination using an optical fiber inserted directly into the tumor, can inhibit the growth of SW1990 tumors with high efficiency in nude mice.

Photodynamic therapy suppresses tumor growth in an in vivo model of human hemangioma

The authors investigated the efficacy of photodynamic therapy against infantile hemangioma using a hemangioma animal model. Eighty-three hemangioma specimens from five children were implanted into nude mice. The gross and volume changes of the implants were evaluated for up to 13 weeks. The histological change of the implant was evaluated at 5 weeks after transplantation. Photodynamic therapy was performed between 6 and 10 weeks after transplantation. The photosensitizer uptake of the implant was evaluated at 24 h after photosensitizer administration. The implant response was evaluated at 0, 12, and 24 h after light delivery. The change in ATF3 levels, a transcription factor induced under severe hypoxic conditions, was investigated immediately after treatment. The implant volume increased slowly during the first 4 weeks and then involuted. At 5 weeks after transplantation, plump endothelial cells formed tightly packed sinusoidal channels, and the endothelial cells were positive for CD31 and GLUT1 expression. At 24 h after photosensitizer administration, confocal analysis showed that the photosensitizer was present within CD31-positive cells. The implant volume was significantly decreased in the treated implants compared with the untreated implants (p < 0.0001). At 24 h after light delivery, most cells had collapsed. ATF3 expression increased gradually and then reached a maximum level at 4 h after treatment. Photodynamic therapy was effective in the treatment of infantile hemangioma. Apoptosis, a major mechanism of hemangioma destruction in the early phase, might be caused by ischemic injury as well as direct effects of photodynamic therapy.

Gender variations in the optical properties of skin in murine animal models

Gender is identified as a significant source of variation in optical reflectance measurements on mouse skin, with variation in the thickness of the dermal layer being the key explanatory variable. For three different mouse strains, the thickness values of the epidermis, dermis, and hypodermis layers, as measured by histology, are correlated to optical reflectance measurements collected with elastic scattering spectroscopy (ESS). In all three strains, males are found to have up to a 50% increase in dermal thickness, resulting in increases of up to 80% in reflectance values and higher observed scattering coefficients, as compared to females. Collagen in the dermis is identified as the primary source of these differences due to its strong scattering nature; increased dermal thickness leads to a greater photon path length through the collagen, as compared to other layers, resulting in a larger scattering signal. A related increase in the observed absorption coefficient in females is also observed. These results emphasize the importance of considering gender during experimental design in studies that involve photon interaction with mouse skin. The results also elucidate the significant impact that relatively small thickness changes can have on observed optical measurements in layered tissue.

Drug and light dose responses to focal photodynamic therapy of single blood vessels in vivo

As part of an ongoing program to develop two-photon (2-gamma) photodynamic therapy (PDT) for treatment of wet-form age-related macular degeneration (AMD) and other vascular pathologies, we have evaluated the reciprocity of drug-light doses in focal-PDT. We targeted individual arteries in a murine window chamber model, using primarily the clinical photosensitizer Visudyne/liposomal-verteporfin. Shortly after administration of the photosensitizer, a small region including an arteriole was selected and irradiated with varying light doses. Targeted and nearby vessels were observed for a maximum of 17 to 25 h to assess vascular shutdown, tapering, and dye leakage/occlusion. For a given end-point metric, there was reciprocity between the drug and light doses, i.e., the response correlated with the drug-light product (DLP). These results provide the first quantification of photosensitizer and light dose relationships for localized irradiation of a single blood vessel and are compared to the DLP required for vessel closure between 1-gamma and 2-gamma activation, between focal and broad-beam irradiation, and between verteporfin and a porphyrin dimer with high 2-gamma cross section. Demonstration of reciprocity over a wide range of DLP is important for further development of focal PDT treatments, such as the targeting of feeder vessels in 2-gamma PDT of AMD.

Photodynamic therapy for palpebral and conjunctival proliferative vascular tumors: clinical case report

Photodynamic therapy (PDT) has been widely used in ophthalmology for the treatment of diverse pathologies, but no experience has been reported in the handling of patients with palpebral vascular and conjunctive malformations with PDT, we describe the case of one patient with a palpebral proliferative vascular tumor, treated successfully using the PDT as a new treatment alternative.

Photodynamic Therapy: Porphyrins and Phthalocyanines as Photosensitizers

The present work is focussed on the principles of photodynamic therapy (PDT), emphasizing the photochemical mechanisms of reactive oxygen species formation and the consequent biochemical processes generated by the action of reactive oxygen species on various biological macromolecules and organelles. This paper also presents some of the most used photosensitizers, including Photofrin, and the new prototypes of photosensitizers, analysing their physicochemical and spectroscopic properties. At this point, the review discusses the therapeutic window of absorption of specific wavelengths involving first- and second-generation photosensitizers, as well as the principal light sources used in PDT. Additionally, the aggregation process, which consists in a phenomenon common to several photosensitizers, is studied. J-aggregates and H-aggregates are discussed, along with their spectroscopic effects. Most photosensitizers have a significant hydrophobic character; thus, the study of the types of aggregation in aqueous solvent is very relevant. Important aspects of the coordination chemistry of metalloporphyrins and metallophthalocyanines used as photosensitizers are also discussed. The state-of-the-art in PDT is evaluated, discussing recent articles in this area. Furthermore, macrocyclic photosensitizers, such as porphyrins and phthalocyanines, are specifically described. The present review is an important contribution, because PDT is one of the most auspicious advances in the therapy against cancer and other non-malignant diseases.

Anti-tumor effect of PDT using Photofrin in a mouse angiosarcoma model

Angiosarcoma, a malignant tumor of vascular endothelial cell origin, is a lethal disease for which complete cure is rarely seen. The objective of this study was to determine the efficiency of photodynamic therapy (PDT) as a new treatment for angiosarcoma. PDT (630 nm, 25 J/cm2) using Photofrin for a mouse angiosarcoma cell line of human origin (ISOS-1) showed that the rate of cell death increased with increase in the concentration of a photosensitizer (LD50: approximately 2 microg/ml). Furthermore, PDT (630 nm, 100 J/cm2) with Photofrin (5 mg/kg, i.v.) in mice transplanted with ISOS-1 cells resulted in complete disappearance of the tumor in 40% of mice and marked inhibition of tumor growth in the remaining 60%. Significant increases in TUNEL-positive cells and Ki-67-positive cells ware seen 4 h after PDT, indicating that PDT led to not only cell death but also inhibition of the proliferation of angiosarcoma cells. The results show that PDT is effective for treatment of angiosarcoma.

Photodynamic therapy of cerebral glioma – A review Part II – Clinical studies

Photodynamic therapy (PDT) is a binary treatment modality that has been used to treat malignant brain tumours for 25 years. The treatment involves the selective uptake of a photosensitizer (PS) by the tumour cells followed by irradiation of the tumour with light of the appropriate wavelength to excite and activate the PS resulting in selective tumour destruction and is a potentially valuable adjunct to surgical excision and other conventional therapies. PDT has undergone extensive laboratory studies and clinical trials with a variety of PS and tumour models. These are discussed with reference mainly to clinical studies involving the PDT of brain tumours.

Terapia fotodinámica en dermatología

Photodynamic therapy (PDT) is a therapeutic modality based on the photooxidation of biological materials induced by a photosensitizer, which selectively locates itself in certain tumorous cells or tissues, so that when illuminated by a light of the right length and at a sufficient dose, these cells are destroyed. In dermatology, PDT with topical 5-aminolevulinic acid or 5-methyl aminolevulinate is very effective in the treatment of actinic keratoses, basal cell carcinomas and Bowen's disease. In addition, very promising results have been obtained in inflammatory pathologies like morphea or sarcoidosis, infections like warts, and cosmetic processes such as photoaging, among others. This article reviews the most significant aspects of PDT in dermatology. First of all, we will review the basic fundamentals of photodynamic treatment. Next, we will outline its clinical applications in dermatology, both in oncological applications and all those dermatological processes in which PDT may play a role in their management. We will also discuss its promising cosmetic application in the treatment of photoaging. We will complete the review with photodiagnosis and the different non-invasive ways to monitor the effectiveness of PDT.

Photodynamic Therapy

ALA-PDT is a safe, well-tolerated, and effective treatment for many dermatologic conditions. Current data most strongly support its use in the treatment of actinic damage, but further investigation into alternative uses continues. Current efficacy is limited primarily by the depth of penetration of the photosensitizing agent and the activating light source. Even with this limitation, the potential applications of PDT are numerous. As new technology is developed to overcome current restraints, the future of PDT is wide open.

Update on hemangiomas and vascular malformations

PURPOSE OF REVIEW

Our knowledge base in the area of vascular anomalies is growing rapidly. With greater understanding of classification and diagnosis, as well as with the numerous areas of research bringing further awareness on the complexity of these lesions, we are improving our ability to treat them. We will attempt in this article to summarize the developments in the field of vascular anomalies over the last year.

RECENT FINDINGS

Emphasis on correct classification is still a high priority in the literature and yet there remains a great deal of misinformation. Many new developments in the basic science of these lesions are allowing better understanding of why these lesions occur while improving our management in these patients. Advances in laser surgery as well as sclerotherapy techniques have improved our ability to treat extensive lesions and also improve patients' quality of life.

SUMMARY

Many new and exciting areas of discovery occur almost daily in the field of vascular anomalies. Due to the breadth of this topic, it is certain that not all articles can be reviewed however the author has tried to present the most recent and clinically relevant breakthroughs in the field.

Treatment of port wine stains with photodynamic therapy, using pulsed dye laser as a Light Source, Compared With Pulsed dye laser alone: A pilot study

BACKGROUND AND OBJECTIVES

Laser-induced photo thermal damage has been combined with photodynamic therapy (PDT) using a systemic photosensitiser to treat vascular lesions. The efficacy of PDT using systemic 5-aminolaevulinic acid (5-ALA) as the photosensitiser and pulsed dye laser (PDL) as the light source in port wine stains (PWS) is unknown.

STUDY DESIGNS/MATERIALS AND METHODS

We conducted an internally controlled pilot study comparing the efficacy of PDT using PDL as a light source, to PDL alone in the treatment of PWS.

RESULTS

The PWS improved slightly in all patients but no significant difference was found between the three treatment arms in terms of lesional lightening or incidence and severity of side effects.

CONCLUSIONS

There was no evidence of increased efficacy of PDT using PDL as a light source compared to PDL alone. There was also no significant difference in adverse events. Further studies using different treatment regimens over longer periods of time may be warranted.

Combined photodynamic and photothermal induced injury enhances damage to in vivo model blood vessels

BACKGROUND AND OBJECTIVES

The degree of port wine stain (PWS) blanching following pulsed dye laser (PDL) therapy remains variable and unpredictable. Because of the limitations of current PDL therapy, alternative treatment approaches should be explored. The objective was to evaluate a novel methodology for selective vascular damage, combined photodynamic (PDT) and photothermal (PDL) treatment, using the in vivo chick chorioallantoic membrane (CAM) model.

STUDY DESIGN/MATERIALS AND METHODS

Thirty microliters of benzoporphyrin derivative monoacid ring A (BPD) solution was administered intraperitoneally into chick embryos at day 12 of development. Study groups were: (1) control (no BPD, no light); (2) BPD alone; (3) continuous wave irradiation (CW) alone (576 nm, 60 mW/cm2, 125 seconds); (4) CW + PDL; (5) BPD+PDL; (6) PDT (BPD+CW); (7) PDL alone (585 nm, 4 J/cm(2)); and (8) PDT+PDL (BPD + CW followed immediately by PDL). Vessels were videotaped prior to, and at 1 hour post-intervention and then assessed for damage based on the following scale: 0, no damage; 1, coagulation; 1.5, vasoconstriction; 2.0, coagulation+vasoconstriction; 2.5, angiostasis; 3.0, hemorrhage. Damage scores were weighted by vessel "order."

RESULTS

PDT + PDL resulted in significantly (P < 0.01) more severe vascular damage than was observed in any other study group: 127% more than PDT, 47% more than PDL alone.

CONCLUSIONS

PDT + PDL is a novel and promising approach for selective vascular damage and may offer a more effective method for treatment of PWS and other vascular skin lesions.