Talaporfin Sodium Concentration Research Articles

Intraoperative Photodiagnosis for Malignant Glioma Using Photosensitizer Talaporfin Sodium.

Objective: The aim of this study was to demonstrate the clinical feasibility of intraoperative photodiagnosis (PD) of malignant brain tumor using talaporfin sodium (TPS), which is an agent used in photodynamic therapy (PDT) for cancers.Methods: Forty-seven patients diagnosed with malignant gliomas by preoperative imaging (42 patients with gliomas and 5 patients with other brain tumors) received an intravenous injection of TPS at 40 mg/m2 24 h before resection. During surgery, these patients were irradiated with diode laser light at 664 nm, and tumor fluorescence was observed. The fluorescence intensity was visually rated on a 3-point rating scale [strong fluorescence, weak fluorescence and no fluorescence]. TPS concentrations in 124 samples from 47 cases were measured by HPLC (High performance liquid chromatography).Results: The fluorescence intensity was confirmed to be weak in all patients with Grade II gliomas and strong in almost all patients with Grade III or IV gliomas, reflecting the histological grade of malignancy. In patients with non-glioma brain tumors except for 1 patient with a metastatic brain tumor, the fluorescence intensity was strong. The mean TPS concentration in tissues was 1.62 μg/g for strong fluorescence areas, 0.67 μg/g for weak fluorescence areas and 0.19 μg/g for no fluorescence areas.Conclusions: Establishment of an appropriate fluorescence observation system enabled fluorescence-guided resection of malignant brain tumors using TPS, and the fluorescence intensity of tumors correlated with the TPS concentrations in tissues. These results suggest that TPS is a useful photosensitizer for both intraoperative fluorescence diagnosis and photodynamic therapy.

Low-density lipoprotein receptor expression is involved in the beneficial effect of photodynamic therapy using talaporfin sodium on gastric cancer cells.

Photodynamic therapy (PDT) is a therapeutic method used to destroy tumor tissue via reactive oxygen. Notably, reactive oxygen is induced by a combination of photosensitizers, including talaporfin sodium (TS) and laser light. Gastric cancer cell lines, MKN45 and MKN74, were used to evaluate the effect of TS-PDT in vitro. The antitumor effect of TS-PDT, which was evaluated via cellular viability assay, on MKN74 was weaker than that on MKN45 cells, suggesting that MKN74 cell could be resistant to TS-PDT. However, using a higher TS concentration or setting a longer treatment time (24 h) resulted in effective TS-PDT treatment on MKN74 cells. In addition, when irradiation power of LED was raised up to 5.06 J/cm2, TS-PDT was able to induce an antitumor effect on MKN74 cells. This suggested that the difference in TS-PDT efficacy between MKN45 and MKN74 cells is based on the difference in cellular uptake of TS. As expected, uptake of TS by MKN74 cells was lower than that by MKN45 cells. The expression levels of low-density lipoprotein (LDL) receptor in MKN74 cells were lower than those in MKN45 cells. With GW3965 treatment, an agonist/activator of Liver X Receptor, LDL receptor expression was reduced, weakening the TS-PDT effect. Furthermore, as a hydroxymethylglutaryl-Coenzyme A reductase inhibitor, treatment using simvastatin increased LDL receptor expression, leading to enhancement of the TS-PDT effect on MKN74 cells. In conclusion, the difference in LDL receptor expression between the two gastric cell lines could influence TS-PDT efficacy; simvastatin may enhance the antitumor effect of TS-PDT through upregulating the LDL receptor even on PDT-resistant gastric cancer cells.

A Three-Compartment Pharmacokinetic Model to Predict the Interstitial Concentration of Talaporfin Sodium in the Myocardium for Photodynamic Therapy: A Method Combining Measured Fluorescence and Analysis of the Compartmental Origin of the Fluorescence.

To evaluate the effectiveness of photodynamic therapy occurring in the interstitial space of the myocardium, we estimated the interstitial concentration of talaporfin sodium in the canine myocardium by constructing a three-compartment pharmacokinetic model based on measured changes in talaporfin sodium plasma concentration and myocardial fluorescence. Differential rate equations of talaporfin sodium concentration in the plasma, interstitial space, and cell compartment were developed with individual compartment volume, concentration, and rate constants. Using measured volume ratios based on histological examinations, we defined that the myocardial fluorescence consisted of the linear addition of fluorescence generated from these three compartments. The rate constants were obtained by fitting to minimize the sum of the squared errors between the measured talaporfin sodium concentrations and the calculated concentrations divided by the number of data points using the conjugate gradient method in MATLAB. We confirmed that this fitting operation may be appropriate, because a coefficient of determination between the measured talaporfin sodium changes and the calculated concentrations using our equations was 0.99. Consequently, to estimate the interstitial concentration in the canine myocardium, we propose a three-compartment pharmacokinetic model construction methodology using measured changes in talaporfin sodium plasma concentration and changes in myocardial fluorescence.

3-compartment pharmacokinetic model for estimation of talaporfin sodium concentration in interstitial space

3-compartment pharmacokinetic model for estimation of talaporfin sodium concentration in interstitial space

Temperature Influence on Myocardial Cell Cytotoxicity of the Extracellular Photosensitization Reaction with Talaporfin Sodium and Serum Proteins at 17°-37°C.

We investigated the binding of talaporfin sodium with albumin and its photocytotoxicity during temperature changes by measuring absorbance spectra. The targeted tissue temperature differs according to the procedure. The photocytotoxicity efficiency should be investigated quantitatively because efficiency changes arising from temperature changes are expected. The temperature dependence of talaporfin sodium binding with human serum albumin (0-20 mg/mL), high-density lipoprotein (0-0.04 mg/mL), and low-density lipoprotein (0-0.14 mg/mL) was investigated at 17°C, 27°C, and 37°C by measurement of absorbance spectra. Cell lethality was measured using a water-soluble tetrazolium-8 assay at 2 h after the photosensitization reaction at 17°C and 37°C. The binding ratios of talaporfin sodium with high-density lipoprotein decreased by 6.3% and those with low-density lipoprotein decreased by 12.8% when the temperature increased from 17°C to 37°C. Cell lethality increased significantly with a temperature rise from 17°C to 37°C at irradiation exposure of 20 and 40 J/cm2 and talaporfin sodium concentration of 20 μg/mL. From our in vitro data, we can predict that the change in photocytotoxicity efficiency would be negligible with a temperature decrease of <5°C from the body temperature in the case of photodynamic ablation with a short drug-light interval.

Irradiance dependence of the conduction block of an in vitro cardiomyocyte wire

BackgroundTo obtain therapeutic condition precisely by in vitro experiment, we studied the irradiance dependence of the electrical conduction blockage caused by a photodynamic reaction using a high extracellular concentration of talaporfin sodium on a novel in vitro cardiomyocyte electrical conduction wire. MethodsThe cardiomyocyte wires were constructed on patterned cultivation cover glass, which had cultivation areas 60μm in width, and a maximum length of 10mm. The talaporfin sodium concentration was set to 20μg/mL. The photodynamic reaction with a high extracellular photosensitizer concentration was performed with a short time interval (approximately 15min) between photosensitizer exposure and irradiation. A 663-nm laser was applied to the cardiomyocyte wire, and the irradiance was varied between 3 and 120mW/cm2. The cardiomyocyte electrical conduction was evaluated using the cross-correlation function of intracellular Ca2+ probe fluorescence brightness from an upper and lower section outside the laser irradiation area of a wire every 10s, which lasted up to 600s. ResultsThe onset of electrical conduction blockage was defined by an 85% decrease in the cross-correlation function, compared with its initial value. The time for the electrical conduction blockage decreased from 600 to 300s as the irradiance was increased. Also, the probability of electrical conduction blockage was found to increase with increasing irradiance. ConclusionsWe found a strong dependence on the irradiance for the time and probability of electrical conduction blockage.

Phototoxicity of Vascular Endothelial Cells Caused by Contact with Talaporfin Sodium for 15–120 Min: In Vitro and In Vivo Studies

To reveal the mechanism of vascular patency in the myocardium after photosensitization immediately after talaporfin sodium (TS) injection in a canine model, we investigated acute injury to vascular endothelial cells (VECs) in vitro and in vivo. There are many reports of vascular shutdown within the target region in photodynamic therapy with TS. Vascular patency within healthy canine myocardium in which a photosensitization reaction starts immediately after injection of TS has been reported. TS fluorescence in human umbilical vein endothelial cells and cell lethality were measured with drug contact time (DCT) up to 120 min at 20 μg/mL. Dependence of radiant exposure on cell lethality with 60 min DCT was investigated using two albumin concentrations that corresponded to those in plasma and interstices. Irradiation (21 mW/cm) outside the adventitia of canine cervical veins for 167 or 667 sec was emitted through a diffuser probe 30 min after intravenous injection of TS (2.5 mg/kg). Veins were extracted ∼30 min after the reaction and stained with von Willebrand factor. Intracellular fluorescence increased, but not cell lethality, with increasing DCT. Cell lethality increased gradually and reached 100% over 20 J/cm2 in the albumin concentration in the interstices. Normal VECs were found at the acute phase over 20 J/cm2 with a TS concentration in plasma of ∼14 μg/mL in vivo. VEC injury after a photosensitization reaction to healthy tissue shortly after TS injection might be low enough for the blood vessels to be patent.

3-compartment pharmacokinetic model for estimation of talaporfin sodium concentration in interstitial space

3-compartment pharmacokinetic model for estimation of talaporfin sodium concentration in interstitial space

Comparison of myocardial cell survival 2 h and 24 h after extracellular talaporfin sodium-induced photodynamic reaction

We have proposed an application of photodynamic reaction for less-heated myocardial ablation which employs talaporfin sodium. Intracellular photodynamic reactions with ongoing uptake have the ability to induce apoptosis over time, raising the possibility of extending the lesion depth. The objective of this study was to understand how, in myocardial cells, the late cell survival levels change by incubation time with talaporfin sodium, and what dependence talaporfin sodium uptake has on the duration of incubation with talaporfin sodium in vitro. Rat myocardial cells were incubated with talaporfin sodium for 5-360 min and intracellular concentrations measured using a fluorescence micro-plate reader after wash. Cell survival was measured using a water-soluble tetrazolium assay at 2 and 24 h after a photodynamic reaction using a red diode laser of 660 nm, following 15-180 min of incubation with talaporfin sodium. Cells were stained with Hoechst 33342 to observe nuclear changes. Intracellular talaporfin sodium concentration increased with incubation time, with a marked increase between 0 and 60 min. Cell survival at 24 h decreased by 20% when the duration of incubation with talaporfin sodium was extended from 15 to 30 min. Following incubation time of 30-180 min with talaporfin sodium, cell survival was decreased by approximately 30% between measurements at 2 and 24 h. The intracellular talaporfin sodium concentration that induced higher levels of late cell death with cell nuclei fragmentation in these cells was approximately 0.2 μg/mL. We obtained the characteristics of late cell death occurrence and talaporfin sodium uptake to myocardial cell with various incubation times with talaporfin sodium.

Effects of albumin binding on photocytotoxicity of extracellular photosensitization reaction using talaporfin sodium to rat myocardial cells

We previously proposed a new treatment for tachyarrhythmia using an extracellular photosensitization reaction occurring in the interstitial space of myocardia shortly after the injection of talaporfin sodium. Using myocardial cells, we studied the photocytotoxicity of this extracellular photosensitization reaction between talaporfin sodium and albumin. The albumin concentrations tested spanned the physiological range found in the interstitial space (0-15 mg/ml) while the talaporfin sodium concentration were varied from 0 to 40 μg/ml. The reactions were conducted in 96-well plates. To obtain the binding ratio and the amount of energy deposited into the photosensitizer, we measured the change in the absorbance spectra of talaporfin sodium solutions containing different concentrations of albumin. Photocytotoxicity to myocardial cell due to the reaction decreased when physiological concentrations of albumin were added to the reaction mix, and decreased sharply when the molar concentration ratio of albumin to talaporfin sodium was between 0.3 and 1.2. A monotonic binding ratio was obtained, ranging from 10 to 80%, at albumin concentrations of 0.1-1.0 mg/ml. We found that the lethality of the extracellular photosensitization reaction towards myocardial cells had a threshold albumin concentration, even though the energy deposited into the talaporfin sodium solution was calculated to be almost constant (4.23 ± 0.19 J/well) in the presence of 0-15 mg/ml albumin. Based on the likely concentration of albumin in the interstitial space, we conclude that the photodynamic efficacy of talaporfin, under conditions used here, will markedly decrease if the albumin level exceeds 0.65 mg/ml.

Fluorescence sensing system by Soret-band LED light excitation for estimating relative talaporfin sodium concentration in skin

The purpose of this study is to establish a sensing system to estimate relative talaporfin sodium concentration in skin to evaluate the risk of skin photosensitivity after photodynamic therapy (PDT) using percutaneous fluorescence spectroscopy. A prototype fluorescence sensing probe was made using a pair of 5-cm-long diffuse tips of plastic optical fibers for excitation light irradiation and fluorescence collection. Talaporfin sodium (2.5mg/kg) was intravenously administrated to three pigs, and the talaporfin sodium concentration in plasma was measured. The fluorescence sensing probe was attached to the skin and excited by a LED light with a peak wavelength of 409 ± 16 nm to obtain the mean area of the talaporfin sodium fluorescence spectral peak (Sfluo). The time history of the talaporfin sodium concentration in tissue was estimated using a two-compartment pharmacokinetic model. The time history of Sfluo was described as a composite function of the time history of the measured talaporfin sodium concentration in plasma and that of the estimated concentration in tissue as a double exponential decay function. The relative talaporfin sodium concentration in tissue and the relative contributions of fluorescence from tissue and plasma to Sfluo were estimated by the fluorescence system with the numerical pharmacokinetic model. Results also show that tissue compression equivalent to venous pressure might be effective to suppress the contribution of talaporfin sodium fluorescence in plasma.

Immediate response and cytotoxicity effect on myocardial cells by extracellular photosensitization reaction varying irradiance.

We investigated the extracellular photosensitization effect on myocardial cells using talaporfin sodium at various irradiance measuring cell lethality dependence on talaporfin sodium concentration and immediate response of intracellular Ca(2+) as a fundamental study of the application for tachyarrhythmia treatment. The myocardial cell lethality was measured 2 h after the photosensitization reaction by WST assay varying the irradiance from 0.12 to 0.66 W/cm(2). The intracellular Ca(2+) of myocardial cell was observed during and until 10 min after the extracellular photosensitization reaction using fluo-4 AM and a confocal microscope varying the irradiance. The linear increasing behavior of the myocardial cell lethality with talaporfin sodium concentration was similarly obtained in the case of 0.12 and 0.29 W/cm(2) in irradiance. The photocytotoxicity was not obtained in the case of 0.46 and 0.66 W/cm(2) in irradiance. The time response of necrosis occurrence after the beginning of the extracellular photosensitization reaction was decreased with the irradiance increasing. We prospect that it may be caused by oxygen depletion in our in vitro system using 96 well plate since the irradiance and talaporfin sodium concentration were higher comparing the in vitro conditions of the general PDT for cancer.