Effects of ursodeoxycholic acid on photodynamic therapy in a murine tumor model.

We previously reported that the efficacy of photodynamic therapy (PDT) in cell culture was enhanced by ursodeoxycholic acid (UDCA), a nontoxic bile acid. In this study, we examined the ability of UDCA to promote tumor control by PDT in the mouse, using the radiation-induced fibrosarcoma tumor and the photosensitizing agent tin etiopurpurin (SnET2). These experiments revealed that the addition of UDCA to a PDT protocol promoted inhibition of tumor growth, a phenomenon unrelated to either altered SnET2 biodistribution or the level of vascular shutdown during irradiation.

Vascular damage after photodynamic therapy of solid tumors: a view and comparison of effect in pre-clinical and clinical models at the University of Louisville.

Microvascular damage that results in blood flow stasis is a frequent consequence of photodynamic therapy. The magnitude of this response is dependent on the type of photosensitizer employed for treatment, the amount of drug and light used in therapy and the time period between drug injection and treatment. This review highlights the mechanisms that lead to blood flow stasis in tumor and normal tissues and discusses methods to increase the selectivity of vascular response.

The treatment of malignant endobronchial obstruction with laser ablation.

Background: We compared a new endoscopic treatment for malignant endobronchial obstruction known as photodynamic therapy (PDT) with the more established therapy of neodymium: yttrium-aluminum garnet laser (Nd:YAG) therapy.

Methods: A retrospective review was conducted of the medical records at our institution from 1988 to 1999 of patients treated for bronchial obstruction by thermal laser vaporization (Nd:YAG) or by PDT using the tunable dye laser in combination with a light-sensitive dye (PDT). The Nd:YAG procedure vaporized the obstructing neoplasm, whereas the PDT procedure photoablated the obstruction.

Analysis of pulmonary microvasculature changes after photodynamic therapy delivered to distant sites.

Photodynamic therapy (PDT) can exert local damage by direct tumor cytotoxicity, by disruption of the microvasculature or by a combination of these effects. Although systemic effects after PDT of small tissue areas (< 1% total body surface area) are unlikely, treatment of larger areas may result in an accumulated effect leading to toxicity. Several investigators have described animal death after high dose PDT to tumors on the hind limb of animals and hypothesized that a toxic shock syndrome caused by vasoactive agents released after PDT is responsible.

Analysis of acute vascular damage after photodynamic therapy using benzoporphyrin derivative (BPD).

Benzoporphyrin derivative monoacid ring A (BPD-MA, verteporfin) is currently under investigation as a photosensitizer for photodynamic therapy (PDT). Since BPD exhibits rapid pharmacokinetics in plasma and tissues, we assessed damage to tumour and muscle microvasculature when light treatment for PDT was given at short times after injection of photosensitizer. Groups of rats with chondrosarcoma were given 2 mg kg(-1) of BPD intravenously 5 min to 180 min before light treatment of 150 J cm(-2) 690 nm.