Biodistribution and photodynamic effects of polyvinylpyrrolidone-hypericin using multicellular spheroids composed of normal human urothelial and T24 transitional cell carcinoma cells

Abstract

Polyvinylpyrrolidone (PVP)-hypericin is a potent photosensitizer that is used in the urological clinic to photodiagnose with high-sensitivity nonmuscle invasive bladder cancer (NMIBC). We examined the differential accumulation and therapeutic effects of PVP-hypericin using spheroids composed of a human urothelial cell carcinoma cell line (T24) and normal human urothelial (NHU) cells. The in vitro biodistribution was assessed using fluorescence image analysis of 5-μm cryostat sections of spheroids that were incubated with PVP-hypericin. The results show that PVP-hypericin accumulated to a much higher extent in T24 spheroids as compared to NHU spheroids, thereby reproducing the clinical situation. Subsequently, spheroids were exposed to different PDT regimes with a light dose ranging from 0.3 to 18J/cm 2 . When using low fluence rates, only minor differences in cell survival were seen between normal and malignant spheroids. High light fluence rates induced a substantial difference in cell survival between the two spheroid types, killing ∼80% of the cells present in the T24 spheroids. It was concluded that further in vivo experiments are required to fully evaluate the potential of PVP-hypericin as a phototherapeutic for NMIBC, focusing on the combination of the compound with methods that enhance the oxygenation of the urothelium. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

Bladder Organoids and Spheroids: Potential Tools for Normal and Diseased Tissue Modelling

“…These findings are consistent with results obtained in another study where spheroids of 400-600 μm in diameter had central necrotic regions (56). A semi-solid technique was used to establish spheroids from normal human urothelium cells (15)(16)(17)(18)(19). Roelants et al showed that cells in normal human urothelial spheroids do not express CK20; thus, urothelial cells in these spheroids do not correspond to fully differentiated superficial umbrella cells (17).…”

“…A majority of studies of normal bladder cells utilized normal human urothelium cells (12)(13)(14)(15)(16)(17)(18)(19)(20)(21). Because the urothelium is the predominant site for bladder cancer, using normal human urothelial cells in experimental models is particularly important for cancer development and tumor targeting studies.…”

“…Further analysis with electron microscopy confirmed the presence of the key features of the native urothelium in the organoids, including microplicae on the surface of apical cells. Urine was a key factor for formation of these organoids as culture of the cells in chambers with the medium in lower and upper compartments did not lead to stratification of the urothelial cell monolayer (18). Smith et al developed a culture system in which a suspension of malignant urothelial cells was mixed with 2-3 mm 3 decellularized fragments of small intestine submucosa in a slowly rotating vessel (37).…”

“…Vandepitte et al used a polyvinyl-L-pyrrolidone complex that de-aggregates hypericin and makes it water soluble and showed its higher accumulation in T24 spheroids compared to unmodified hypericin (18). Roelants et al explored the differential uptake of hypericin in the presence and absence of human serum albumin (16), including a fluorescein isothiocyanate-labelled variety, which allowed for deeper penetration of hypericin into multicellular cancer spheroids (17,19).…”

New Frontier in Hypericin-Mediated Diagnosis of Cancer with Current Optical Technologies

“…These include organic solvents, such as ethanol, tetrahydrofuran, and acetone, and also serum proteins which are reported to dissolve most hydrophobic compounds 34,74,76,100. Therefore, the focus of recent studies by research groups involved in fluorescence diagnosis of cancer is directed toward new formulations to be used with HY, like using Solketal as absorption enhancer,42 polyvinylpyrrolidone (PVP)93 and cyclodextrins as solubilizers,78 and NMP as penetration enhancer 76. For example, our lab investigated HY formulated with different concentrations of NMP and found effective solubilizing and delivery of HY to the target site, bladder urothelium in this study 77.…”