Confocal laser scanning microscopy of urinary bladder after intravesical instillation of a fluorescent dye

Gel-Based Nanocarrier for Intravesical Chemotherapy Delivery: In Vitro and In Vivo Study

Intravesical administration of chemotherapeutic agents can enhance drug accumulation in tumors and reduce systemic side effects. Nanocarriers were developed for intravesical administration and exploit the permeation enhancement effect. In vitro permeation evaluation, the drug transdermal amount and accumulation amounts in the tissue of gemcitabine-loaded nanocarriers through biological membrane significantly increased about 14.8~33.0-fold and 1.5~14.1-fold respectively, when compared to a control group of 1% gemcitabine saline solution. In in vivo intravesical administration, the drug accumulation amount in bladder tissue of nanocarrier of 75.2 ± 5.4 μg was revealed as being comparably higher than that of the control group of 44.8 ± 6.4 μg. In confocal laser scanning microscopy imagery, the penetration depth of fluorescent dyes-rhodamine was increased from 80 μm up to 120 μm when a nanocarrier was used. This result implies that the nanocarrier is a promising drug delivery agent for intravesical administration.

Simultaneous viewing of individual cells and ambient microvasculature using optical absorption and fluorescence contrasts

Viewing individual cells and ambient microvasculature simultaneously is crucial for understanding tumor angiogenesis and microenvironments. We developed a confocal fluorescence microscopy (CFM) and photoacoustic microscopy (PAM) dual-modality imaging system that can assess fluorescent contrast and optical absorption contrast in biologic samples simultaneously. After staining tissues with fluorescent dye at an appropriate concentration, each laser pulse can generate not only sufficient fluorescent signals from cells for CFM but also sufficient photoacoustic signals from microvessels for PAM. To explore the potential of this system for diagnosis of bladder cancer, experiments were conducted on a rat bladder model. The CFM image depicts the morphology of individual cells, showing not only large polygonal umbrella cells but also intracellular components. The PAM image acquired at the same time provides complementary information on the microvascular distribution in the bladder wall, ranging from large vessels to capillaries. This device provides an opportunity to realize both histologic assay and microvascular characterization simultaneously. The combination of the information of individual cells and local microvasculature in the bladder offers the capability of envisioning the viability and activeness of these cells and holds promise for more comprehensive study of bladder cancer in vivo.

Dye-enhanced multimodal confocal imaging as a novel approach to intraoperative diagnosis of brain tumors

Intraoperative diagnosis plays an important role in accurate sampling of brain tumors, limiting the number of biopsies required and improving the distinction between brain and tumor. The goal of this study was to evaluate dye-enhanced multimodal confocal imaging for discriminating gliomas from nonglial brain tumors and from normal brain tissue for diagnostic use. We investigated a total of 37 samples including glioma (13), meningioma (7), metastatic tumors (9) and normal brain removed for nontumoral indications (8). Tissue was stained in 0.05 mg/mL aqueous solution of methylene blue (MB) for 2-5 minutes and multimodal confocal images were acquired using a custom-built microscope. After imaging, tissue was formalin fixed and paraffin embedded for standard neuropathologic evaluation. Thirteen pathologists provided diagnoses based on the multimodal confocal images. The investigated tumor types exhibited distinctive and complimentary characteristics in both the reflectance and fluorescence responses. Images showed distinct morphological features similar to standard histology. Pathologists were able to distinguish gliomas from normal brain tissue and nonglial brain tumors, and to render diagnoses from the images in a manner comparable to haematoxylin and eosin (H&E) slides. These results confirm the feasibility of multimodal confocal imaging for intravital intraoperative diagnosis.

Non-linear fluorescence lifetime imaging of biological tissues

In recent years fluorescence microscopy has become a widely used tool for tissue imaging and spectroscopy. Optical techniques, based on both linear and non-linear excitation, have been broadly applied to imaging and characterization of biological tissues. Among fluorescence techniques used in tissue imaging applications, in recent years two and three-photon excited fluorescence have gained increased importance because of their high-resolution deep tissue imaging capability inside optically turbid samples. The main limitation of steady-state fluorescence imaging techniques consists in providing only morphological information; functional information is not detectable without technical improvements. A spectroscopic approach, based on lifetime measurement of tissue fluorescence, can provide functional information about tissue conditions, including its environment, red-ox state, and pH, and hence physiological characterization of the tissue under investigation. Measurement of the fluorescence lifetime is a very important issue for characterizing a biological tissue. Deviation of this property from a control value can be taken as an indicator of disorder and/or malignancy in diseased tissues. Even if much work on this topic has still to be done, including the interpretation of fluorescence lifetime data, we believe that this methodology will gain increasing importance in the field of biophotonics. In this paper, we review methodologies, potentials and results obtained by using fluorescence lifetime imaging microscopy for the investigation of biological tissues.

Time- and Spectral-resolved two-photon imaging of healthy bladder mucosa and carcinoma in situ

Combined non-linear imaging techniques were used to deeply image human ex-vivo fresh biopsies of bladder as well as to discriminate between healthy bladder mucosa and carcinoma in situ. Morphological examination by two-photon excited fluorescence and second-harmonic generation has shown a good agreement with corresponding common routine histology performed on the same samples. Tumor cells appeared slightly different in shape and with a smaller cellular-to-nuclear dimension ratio with respect to corresponding normal cells. Further differences between the two tissue types were found in both spectral emission and fluorescence lifetime distribution by performing temporal- and spectral- resolved analysis of fluorescence. This method may represent a promising tool to be used in a multi-photon endoscope, in a confocal endoscope or in a spectroscopic probe for in-vivo optical diagnosis of bladder cancer.

Anwendung der optischen Kohärenztomographie (OCT) bei der Darstellung von Urothelerkrankungen der Harnblase

PURPOSE

The technique of optical coherence tomography (OCT) has significantly improved over the last few years. This new diagnostic procedure allows imaging of tissue structure of the bladder wall during cystoscopy with high resolution.

MATERIALS AND METHODS

The penetration depth of OCT is limited to 2.5 mm. The resolution is approximately 15 microm. Fifty patients with different clinical conditions of the bladder were examined. Altogether 488 OCT images were generated.

RESULTS

OCT of normal bladder mucosa clearly shows a differentiation between urothelium, lamina propria, and smooth muscle. Cystitis and metaplasia are characterized by blurring of the laminated structure and thickening of the epithelial layer. In malignant areas there is complete loss of the regular layered tissue structure.

CONCLUSION

OCT improves the diagnosis of flat lesions of the urothelium. It has the potential for facilitating intraoperative staging of malignant areas in the bladder.

Endoscopic confocal fluorescence microscopy of normal and tumor bearing rat bladder

PURPOSE

We evaluated the possibility of performing endoscopic fiber-optic confocal microscopy in a rat bladder model and we distinguished different cell types.

MATERIAL AND METHODS

Rhodamine 123 (Molecular Probes, Eugene, Oregon) (100 microM) was instilled for 30 minutes in 5 tumor bearing rat bladders (AY27). Five normal rats served as controls. A Cell-viziotrade mark confocal microscopy fiber was placed transurethrally in contact with normal or transformed bladder wall. Frozen sections were obtained from the same spots and subjected to conventional fluorescence microscopy and anatomical-pathological analysis.

RESULTS

The different cells types present in rat epithelium (umbrella, intermediate and basal cells) could easily be identified with the Cell-viziotrade mark device due to their differences in morphology and fluorescence intensity. Individual AY-27 cells could not be demarcated due to the strong fluorescence signal but the entire tumor appeared as a brightly homogenous fluorescent blot surrounded by small inflammatory cells.

CONCLUSIONS

We report the feasibility of endoscopic, in vivo, fiber-optic confocal microscopy in the rat bladder. We distinguished tumors from normal epithelium and visualized the different epithelial cell types in nontransformed rat bladder epithelium.