Fluoreszenzzystoskopie: Perspektiven in Klinik und Forschung

Zusammenfassung: Viele Studien bestätigen das klinische Interesse an der photodynamischen Diagnostik (PDD) zur Behandlung des nicht muskelinvasiven Harnblasenkarzinoms. Die PDD oder Fluoreszenzzystoskopie ist bei der Detektion okkulter Urothelkarzinome von großem Wert und mag einen positiven Einfluss auf die rezidivfreie Überlebenszeit und die Prognose haben. Dennoch wird ihre Spezifität mit hoher Variabilität, hauptsächlich in Relation mit den verschiedenen Krankheitsprofilen, in den einzelnen Studien angegeben. Neue Bildgebungstechniken zur Verbesserung der visuellen Beurteilung der Harnblasenwand werden daher entwickel

Characterization of depolarizing optical media by means of the entropy factor: application to biological tissues

Polarized light imaging is a potential tool to obtain an adequate description of the properties of depolarizing media such as biological tissues. In many biomedical applications, for instance, dermatology, ophthalmology, or urology, imaging polarimetry provides a noninvasive diagnosis of a wide range of disease states, and, likewise, it could be applied to the study of internal tissues though the use of endoscopes that use optical fibers. We introduce an algebraic method, based on the Mueller-coherence matrix, for a clearer analysis of the polarization characteristics of depolarizing media via the entropy factor. First-order errors introduced by the measurement system are corrected. Entropy defines three kinds of media according to their depolarizing behavior, and several examples corresponding to each region are shown. The calculation of this factor provides clearer information than that provided by the traditional Mueller matrix in the analysis of biological tissue properties by polarization measurement techniques

Angiostasis-induced vascular normalization can improve photodynamic therapy

In a recent issue, Cellular and Molecular Life Sciences published on the combination of photodynamic therapy (PDT) and anti-angiogenesis for the treatment of cancer [1]. In this paper, Bhuvaneswari and colleagues elegantly review this field. The idea behind combining these two therapeutic strategies is based on the observation that PDT can lead to vessel closure, and hence hypoxia, as well as other tissue damage resulting in inflammation. This combination of hypoxia and inflammation can in turn cause the enhanced release of angiogenic growth factors (vascular endothelial growth factor, VEGF) followed by the regrowth of the targeted neoplastic tissue. Thus, it appeared logical to try to block the VEGF pathways after PDT, for instance by applying antibodies against VEGF. This type of combination therapy is not limited to the treatment of cancer. Indeed, for the treatment of certain forms of exudative macular degeneration, recently published results from a phase II clinical study demonstrate great promise for the combination of PDT (Visudyne) together with anti-VEGF-A therapy using humanized antibody fragments (Lucentis). PDT as a monotherapy has clearly been shown to be effective in treating some early stage superficial cancers. However, for more advanced cancers, where PDT monotherapy appears to be less effective, the usefulness of the photodynamic approach followed by anti-VEGF therapy has not yet been extensively demonstrated in the clinic.ISSN:1420-682XISSN:1420-907

Low-Dose Vascular Photodynamic Therapy Decreases Tumor Interstitial Fluid Pressure, which Promotes Liposomal Doxorubicin Distribution in a Murine Sarcoma Metastasis Model.

INTRODUCTION: Solid tumors are known to have an abnormal vasculature that limits the distribution of chemotherapy. We have recently shown that tumor vessel modulation by low-dose photodynamic therapy (L-PDT) could improve the uptake of macromolecular chemotherapeutic agents such as liposomal doxorubicin (Liporubicin) administered subsequently. However, how this occurs is unknown. Convection, the main mechanism for drug transport between the intravascular and extravascular spaces, is mostly related to interstitial fluid pressure (IFP) and tumor blood flow (TBF). Here, we determined the changes of tumor and surrounding lung IFP and TBF before, during, and after vascular L-PDT. We also evaluated the effect of these changes on the distribution of Liporubicin administered intravenously (IV) in a lung sarcoma metastasis model. MATERIALS AND METHODS: A syngeneic methylcholanthrene-induced sarcoma cell line was implanted subpleurally in the lung of Fischer rats. Tumor/surrounding lung IFP and TBF changes induced by L-PDT were determined using the wick-in-needle technique and laser Doppler flowmetry, respectively. The spatial distribution of Liporubicin in tumor and lung tissues following IV drug administration was then assessed in L-PDT-pretreated animals and controls (no L-PDT) by epifluorescence microscopy. RESULTS: L-PDT significantly decreased tumor but not lung IFP compared to controls (no L-PDT) without affecting TBF. These conditions were associated with a significant improvement in Liporubicin distribution in tumor tissues compared to controls (P < .05). DISCUSSION: L-PDT specifically enhanced convection in blood vessels of tumor but not of normal lung tissue, which was associated with a significant improvement of Liporubicin distribution in tumors compared to controls

Studying biological tissue with fluorescence lifetime imaging: microscopy, endoscopy, and complex decay profiles

We have applied fluorescence lifetime imaging (FLIM) to the autofluorescence of different kinds of biological tissue in vitro, including animal tissue sections and knee joints as well as human teeth, obtaining two-dimensional maps with functional contrast. We find that fluorescence decay profiles of biological tissue are well described by the stretched exponential function (StrEF), which can represent the complex nature of tissue. The StrEF yields a continuous distribution of fluorescence lifetimes, which can be extracted with an inverse Laplace transformation, and additional information is provided by the width of the distribution. Our experimental results from FLIM microscopy in combination with the StrEF analysis indicate that this technique is ready for clinical deployment, including portability that is through the use of a compact picosecond diode laser as the excitation source. The results obtained with our FLIM endoscope successfully demonstrated the viability of this modality, though they need further optimization. We expect a custom-designed endoscope with optimized illumination and detection efficiencies to provide significantly improved performance. © 2003 Optical Society of America.Peer Reviewe

Fluoreszenzzystoskopie. Perspektiven in Klinik und Forschung [Fluorescence cystoscopy : Perspective in clinical practice and research = Cystoscopie de fluorescence : Perspective clinique et recherche]

Many studies confirm the clinical interest of photodynamic diagnostics (PDD) in non-muscle invasive bladder cancer management. PDD or fluorescence cystoscopy is not only of great value in occult urothelial cancer detection, but may have a positive impact on disease-free survival and prognosis. Yet, its specificity is found to be highly variable between studies mainly in relation to different disease profiles. New imaging techniques aimed at enhancing visualization to assess the bladder wall are under development

Intra-Arterial Drug and Light Delivery for Photodynamic Therapy Using Visudyne (R): Implication for Atherosclerotic Plaque Treatment

Photodynamic therapy (PDT), which is based on the activation of photosensitizers with light, can be used to reduce plaque burden. We hypothesized that intra-arterial photosensitizer administration and photo-activation will lead to high and rapid accumulation within the plaque with reduced systemic adverse effects. Thus, this intra-arterial PDT would be expected to have less side effects and due to the short time involved would be compatible with percutaneous coronary interventions. Aim: We characterized the dose-dependent uptake and efficacy of intra-arterial PDT using Liposomal Verteporfin (Visudyne (R)), efficient for cancer-PDT but not tested before for PDT of atherosclerosis. Methods and Results: Visudyne (R) (100, 200, and 500 ng/ml) was perfused for 530 min in atherosclerotic aorta isolated from ApoE(-/-) mice. The fluorescence Intensity (FI) after 15 min of Visudyne (R) perfusion increased with doses of 100 (FI-5.5 +/- 1.8), 200 (FI-31.9 +/- 1.9) or 500 ng/ml (FI-42.9 +/- 1.2). Visudyne (R) (500 ng/ml) uptake also increased with the administration time from 5 min (FI-9.8 +/- 2.5) to 10 min (FI-23.3 +/- 3.0) and 15 min (FI-42.9 +/- 3.4) before reaching saturation at 30 min (FI-39.3 +/- 2.4) contact. Intra-arterial PDT (Fluence: 100 and 200 J/cm(2), irradiance-334 mW/cm(2)) was applied immediately after Visudyne (R) perfusion (500 ng/ml for 15 min) using a cylindrical light diffuser coupled to a diode laser (690 nm). PDT led to an increase of ROS (Dihydroethidium; FI-6.9 +/- 1.8, 25.3 +/- 5.5, 43.4 +/- 13.9) and apoptotic cells (TUNEL; 2.5 +/- 1.6, 41.3 +/- 15.3, 58.9 +/- 6%), mainly plaque macrophages (immunostaining; 0.3 +/- 0.2, 37.6 +/- 6.4, 45.3 +/- 5.4%) respectively without laser irradiation, or at 100 and 200 J/cm2. Limited apoptosis was observed in the medial wall (0.5 +/- 0.2, 8.5 +/- 4.7, 15.3 +/- 12.7%). Finally, Visudyne (R)-PDT was found to be associated with reduced vessel functionality (Myogram). Conclusion: We demonstrated that sufficient accumulation of Visudyne (R) within plaque could be achieved in short-time and therefore validated the feasibility of local intravascular administration of photosensitizer. Intra-arterial Visudyne (R)-PDT preferentially affected plaque macrophages and may therefore alter the dynamic progression of plaque development

Perturbative forward solver software for small localized fluorophores in tissue

In this paper a forward solver software for the time domain and the CW domain based on the Born approximation for simulating the effect of small localized fluorophores embedded in a non-fluorescent biological tissue is proposed. The fluorescence emission is treated with a mathematical model that describes the migration of photons from the source to the fluorophore and of emitted fluorescent photons from the fluorophore to the detector for all those geometries for which Green’s functions are available. Subroutines written in FORTRAN that can be used for calculating the fluorescent signal for the infinite medium and for the slab are provided with a linked file. With these subroutines, quantities such as reflectance, transmittance, and fluence rate can be calculated