The detection of phthalocyanine fluorescence in normal rat bladder wall using sensitive digital imaging microscopy

Abstract

Summary The ability to detect photosensitisers in tissue at a microscopical level is important when studying photodynamic therapy (PDT) in both normal and malignant tissue. We have studied the fluorescence distribution of aluminium sulphonated phthalocyanine (AlSPc) in the normal rat bladder using a cooled CCD (charge coupled device) imaging system with computerised image processing. This system makes it possible to carry out a quantitative assessment of photosensitiser fluorescence in the various layers of the bladder wall. The highest fluorescence intensities were obtained within I h of intravenous administration but there was little selectivity of uptake between layers. AlSPc was eliminated from the deeper muscle layers more quickly than from the superficial layers of the bladder wall so that by 24 h a 4:1 ratio of fluorescence intensity was apparent which persisted at least until 72 h, although the absolute amount of photosensitiser declined. Following irradiation by red light (675 nm), photobleaching of the sensitiser in the deeper layers further increased this ratio. Direct absorption of AlSPc by the bladder wall following intravesical administration proved unreliable.

The influence of iron chelators on the accumulation of protoporphyrin IX in 5-aminolaevulinic acid-treated cells

“…Since most porphyrins exhibit a characteristic red fluorescence, their tumour-localising properties can be used for tumour detection (Lipson et al, 1967;Pope et al, 1991). The photosensitising properties of porphyrins, together with their tumour-localising properties, were first exploited for therapeutic purposes by Auler and Banzer (1943).…”

The effect of aminolaevulinic acid-induced, protoporphyrin IX-mediated photodynamic therapy on the cremaster muscle microcirculation in vivo

“…Sensitive fluorescence microscopy of frozen sections taken after sensitisation with phthalocyanine has demonstrated localisation of fluorescence to well-vascularised areas of stroma in the rat colon (Barr et al. 1988), rat bladder (Pope et al, 1991a), and hamster pancreas (Chatlani et al, 1992). Using a radioactive microsphere technique, blood flow to transplantable bladder tumours has been shown to be markedly reduced after treatment with chloroaluminium tetrasulphophthalocyanine and light (Selman et al, 1986), indicating that HPD and phthalocyanines have similar effects on the microvasculature.…”

Increasing the effect of photodynamic therapy on the RIF-1 murine sarcoma, using the bioreductive drugs RSU1069 and RB6145

“…Recent experimental studies with the second generation photosensitiser, disulphonated aluminium phthalocyanine, AlS2Pc, using fluorescence microscopy, have shown that this photosensitiser is highly concentrated in the vasculature of normal rat colon and bladder 1 h after administration Pope et al, 1991). This has also been shown for DMH-induced colon tumours in rats (P.T.…”

“…They were snap frozen in liquid nitrogen, and two serial cryostat sections were taken (10 tm slices) from each tumour, one section for staining with haematoxylin and eosin and the other for fluorescence microscopy analysis using a cooled charge-coupled device (CCD) (Barr et al, 1988;Pope et al, 1991). A slightly modified technique was used as described by Chatlani et al (1991).…”