Light propagation in two-layered turbid media having an infinitely thick second layer is investigated in the steady-state, frequency, and time domains. A solution of the diffusion approximation to the transport equation is derived by employing the extrapolated boundary condition. We compare the reflectance calculated from this solution with that computed with Monte Carlo simulations and show good agreement. To investigate if it is possible to determine the optical coefficients of the two layers and the thickness of the first layer, the solution of the diffusion equation is fitted to reflectance data obtained from both the diffusion equation and the Monte Carlo simulations. Although it is found that it is, in principle, possible to derive the optical coefficients of the two layers and the thickness of the first layer, we concentrate on the determination of the optical coefficients, knowing the thickness of the first layer. In the frequency domain, for example, it is shown that it is sufficient to make relative measurements of the phase and the steady-state reflectance at three distances from the illumination point to obtain useful estimates of the optical coefficients. Measurements of the absolute steady-state spatially resolved reflectance performed on two-layered solid phantoms confirm the theoretical results.

To understand the effects of substitution patterns on photosensitizing the ability of boron dipyrromethene (BODIPY), two structural variations that either investigate the effectiveness of various iodinated derivatives to maximize the "heavy atom effect" or focus on the effect of extended conjugation at the 4-pyrrolic position to red-shift their activation wavelengths were investigated. Compounds with conjugation at the 4-pyrrolic position were less photocytotoxic than the parent unconjugated compound, while those with an iodinated BODIPY core presented better photocytotoxicity than compounds with iodoaryl groups at the meso-positions. The potency of the derivatives generally correlated well with their singlet oxygen generation level. Further studies of compound 5 on HSC-2 cells showed almost exclusive localization to mitochondria, induction of G(2)/M-phase cell cycle block, and onset of apoptosis. Compound 5 also extensively occluded the vasculature of the chick chorioallantoic membrane. Iodinated BODIPY structures such as compound 5 may have potential as new photodynamic therapy agents for cancer.

The antimetastatic ruthenium(II) compounds [Ru(η(6)-p-cymene)Cl(2)(PTA)] (PTA = 1,3,5-triaza-7-phosphaadamantane) (RAPTA-C) and [Ru(η(6)-toluene)Cl(2)(PTA)] (RAPTA-T), as well as their analogues [Ru(η(6)-p-cymene)Cl(2)(DAPTA)] (DAPTA = (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane)) (DAPTA-C) and [Ru(η(6)-toluene)Cl(2)(DAPTA)] (DAPTA-T), respectively, were tested in in vitro bioassays for endothelial cell function. All compounds showed low toxicity profiles and similar dose-dependent antiproliferative effects in endothelial cells at ≥100 μg/mL (∼200 μM). EC migration, measured 6 h after drug exposure, was also efficiently inhibited (ED(50) of ∼300 μg/mL, ∼500 μM, for all compounds). Since no cytostatic effect was noted, the inhibition of proliferation was considered mainly to consist of antiangiogenic activity. RAPTA-T and DAPTA-C were also tested in vivo in the chicken chorioallantoic membrane (CAM) assay and found to inhibit CAM development. Importantly, effective prevention of revascularization of the CAM after vaso-occlusive photodynamic therapy was observed. The reported ruthenium complexes show promising antimetastatic activity involving inhibition of angiogenesis and therefore are attractive agents for development of anticancer therapies based on combination of chemo- and angiostatic treatments.

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HAL fluorescence cystoscopy is a new, sensitive, promising diagnostic procedure that showed improved detection of bladder tumors, in particular CIS. The procedure is well tolerated and can easily be implemented in current clinical practice.

The purpose of this review is to compile preclinical and clinical results on phthalocyanines (Pcs) as photosensitizers (PS) for Photodynamic Therapy (PDT) and contrast agents for fluorescence imaging. Indeed, Pcs are excellent candidates in these fields due to their strong absorbance in the NIR region and high chemical and photo-stability. In particular, this is mostly relevant for their in vivo activation in deeper tissular regions. However, most Pcs present two major limitations, i.e., a strong tendency to aggregate and a low water-solubility. In order to overcome these issues, both chemical tuning and pharmaceutical formulation combined with tumor targeting strategies were applied. These aspects will be developed in this review for the most extensively studied Pcs during the last 25 years, i.e., aluminium-, zinc- and silicon-based Pcs.

Fluorescence photodetection (PD) and photodynamic therapy (PDT) are techniques currently under clinical assessment for both visualization and local destruction of malignant tumours and premalignant lesions. One drawback of these methods found with some photosensitizers is a more or less long-term cutaneous photosensitivity (Wagnières et al, 1998;Dougherty et al, 1990). A more recent strategy for administering photosensitizers involves the application of 5-aminolaevulinic acid (ALA) in order to stimulate the formation of protoporphyrin IX (PpIX) in situ. The exogenous ALA bypasses the negative feedback control from haem to ALA synthase that catalyses the condensation of glycine and succinyl-coenzyme A (CoA). Given in excess, exogenous ALA thus can result in a temporary accumulation of PpIX, in particular, in cells with higher metabolic turnover. Since PPIX has fairly good photosensitizing properties (Cox et al, 1982;Kennedy et al, 1990) proposed ALA as a possible photodynamic agent. Following this pioneering work, this treatment modality has been widely studied for various cancers (Kennedy et al, 1992;Peng et al, 1992;Svanberg et al, 1994).As well as for the PDT of malignant or premalignant lesions, ALA-induced PpIX is now being used for the detection of such lesions. This technique has been shown to work, among other applications, in urology, where easy instillation in the bladder, combined with the fact that this organ is readily accessible endoscopically, makes it an ideal object. Alongside classical techniques such as cytology or white light examination, fluorescence PD by ALA-induced PpIX provides some advantages (Leveckis et al, 1994;Kriegmair et al, 1996;Jichlinski et al, 1997). This inspection modality allows an exact mapping which pinpoints, with a high level of sensitivity and specificity, the locations of carcinoma in situ (CIS) as well as early stages of cancer-like dysplasias, which are normally difficult to recognize under white light examination.However, when using topically instilled ALA for the PDT of CIS and precancerous lesions, this modality appears to be limited by the amount of ALA that enter the target cells or by the tissue penetration and the distribution of the resulting PpIX in the targeted tissue. Almost all of these possible disadvantages accompanying the use of ALA can be ascribed to the physical-chemical properties of the molecule itself. Applied under physiological conditions, ALA is a zwitterion (Novo et al, 1996). Because the lipid bilayer of biological membranes is relatively impermeable to charged molecules, the cellular uptake of ALA is shallow. Consequently, in order to increase the transport across cellular membranes, fairly high drug doses and increased administration times have to be used. This deficiency results in a low penetration depth (Warloe et al, 1992;Loh et al, 1993;Peng et al, 1995) and an ALA-induced PpIX distribution, which is not optimized for the PDT of the deep layers of nodular lesions in the urothelium (Iinuma et al, 1995;Chang et al, 1996) after topical A...

Drug combinations can improve angiostatic cancer treatment efficacy and enable the reduction of side effects and drug resistance. Combining drugs is non-trivial due to the high number of possibilities. We applied a feedback system control (FSC) technique with a population-based stochastic search algorithm to navigate through the large parametric space of nine angiostatic drugs at four concentrations to identify optimal low-dose drug combinations. This implied an iterative approach of in vitro testing of endothelial cell viability and algorithm-based analysis. The optimal synergistic drug combination, containing erlotinib, BEZ-235 and RAPTA-C, was reached in a small number of iterations. Final drug combinations showed enhanced endothelial cell specificity and synergistically inhibited proliferation (p < 0.001), but not migration of endothelial cells, and forced enhanced numbers of endothelial cells to undergo apoptosis (p < 0.01). Successful translation of this drug combination was achieved in two preclinical in vivo tumor models. Tumor growth was inhibited synergistically and significantly (p < 0.05 and p < 0.01, respectively) using reduced drug doses as compared to optimal single-drug concentrations. At the applied conditions, single-drug monotherapies had no or negligible activity in these models. We suggest that FSC can be used for rapid identification of effective, reduced dose, multi-drug combinations for the treatment of cancer and other diseases.Electronic supplementary materialThe online version of this article (doi:10.1007/s10456-015-9462-9) contains supplementary material, which is available to authorized users.