Fluorospectral study of the rat brain and glioma in vivo

Diagnostic potential of autofluorescence for an assisted intraoperative delineation of glioblastoma resection margins

The intrinsic autofluorescence properties of biological tissues can be affected by the occurrence of histological and biochemical alterations induced by pathological processes. In this study the potential of autofluorescence to distinguish tumor from normal tissues was investigated with the view of a real-time diagnostic application in neurosurgery to delineate glioblastoma resection margins. The autofluorescence properties of nonneoplastic and neoplastic tissues were analyzed on tissue sections and homogenates by means of a microspectrofluorometer, and directly on patients affected by glioblastoma multiforme, during surgery, with a fiber-optic probe. Scan-microspectrofluorometric analysis on tissue sections evidenced a reduction of emission intensity and a broadening of the main emission band, along with a redshift of the peak position, from peritumoral nonneoplastic to neoplastic tissues. Differences in both spectral shape and signal amplitude were found in patients when the glioblastoma lesion autofluorescence was compared with those of cortex and white matter taken as healthy tissues. Both biochemical composition and histological organization contribute to modify the autofluorescence emission of neoplastic, with respect to nonneoplastic, brain tissues. The differences found in the in vivo analysis confirm the prospects for improving the efficacy of tumor resection margin delineation in neurosurgery.

Comparative study on the ALA photodynamic effects of human glioma and meningioma cells

BACKGROUND AND OBJECTIVE

The purpose of this study was to compare the differential susceptibility to photodynamic therapy (PDT) mediated damage in human U-105MG glioma cells and CH-157MN meningioma cells in vitro using 5-amino-levulinic acid (ALA) as photosensitizer, and to determine if growth factors would enhance PDT-mediated damage of these cells.

STUDY DESIGN/MATERIALS AND METHODS

U-105MG or CH-157MN cells were irradiated with polychromatic light in the presence of ALA. A Xenon lamp (150 W) was used as the light source. For the study on the effect of growth factor on ALA-PDT, cells were cultured in serum free medium for 24 hours. Epidermal growth factor (EGF), basic fibroblast growth factor (bFGF), or platelet derived growth factor BB (PDGF-BB) was added to achieve a final concentration of 50 ng/ml. 30 minutes later, cells were incubated with ALA (100 microg/ml) for 24 hours, washed, and irradiated with light (11 J/cm2). MTT tetrazolium assays were performed 24 hours after light irradiation.

RESULTS

The inhibition of metabolic cellular function in U-105MG cells by ALA depended on both light energy density and ALA concentration. The susceptibility to ALA-PDT was profoundly lower for CH-157MN meningioma cells than U-105MG glioma cells. When incubated with ALA (100 microg/ml), U-105MG cells exhibited an LD50 around 8 J/cm2 of light irradiation, whereas that of CH-157MN cells was more than 25 J/cm2. EGF, bFGF, or PDGF-BB did not have any effects on the susceptibility of these two cell lines to ALA-PDT.

CONCLUSION

ALA-PDT was more effective in killing U-105MG glioma cells than CH-157MN meningioma cells. The differential susceptibility was likely due to differential accumulation of PpIX in these cells. EGF, bFGF, or PDGF-BB did not have stimulatory or inhibitory effect on the efficiency of ALA-PDT.

Brain tissue autofluorescence: an aid for intraoperative delineation of tumor resection margins

The intrinsic autofluorescence properties of biological tissues can change depending on alterations induced by pathological processes. Evidence has been reported concerning the application of autofluorescence as a parameter for in situ cancer detection in several organs. In this paper, autofluorescence properties of normal and tumor tissue in the brain are described, suitable for a real-time diagnostic application. Data were obtained both on ex vivo resected samples, by microspectrofluorometric techniques, and in vivo, during surgical operation, by means of fiberoptic probe. Significant differences were found in autofluorescence emission properties between normal and tumor tissues, in terms of both spectral shape and signal amplitude, that confirm the potential of autofluorescence as a parameter to distinguish neoplastic from normal condition. The noninvasiveness of the technique opens up interesting prospects for improving the efficacy of neurosurgical operations, by allowing an intraoperative delineation of tumor resection margins.

Physiological and pathological factors of human breast disease that can influence optical diagnosis

The 'normal' human female breast is a very complex organ that changes considerably during development, pregnancy and menopause. In addition, it is an excretory organ that, during lactation, discharges various metabolites and certain drugs that can be optically active. Optical diagnosis of breast cancers requires detection of differential concentrations of 1) various absorbers and scatterers or 2) native or exogenous fluorophores to distinguish cancers from surrounding 'normal' and benign breast tissues. The differential concentrations are due to the biology of the cancer cells and the host responses to the cancer growth. For most patients, the cancer will be intermixed with a complex 3-dimensional array of 'normal' breast tissue and benign breast lesions. This complexity will challenge the optical biopsy investigator but, with the recent advances in our understanding of light transport, optical diagnostic techniques and devices can be developed to complement and supplement current breast cancer screening techniques.