Differential effects of photodynamic therapy on morphologically distinct tumor cells derived from a single precursor cell

Digital holographic microscopy in label-free analysis of cultured cells' response to photodynamic treatment

A methodology providing noninvasive monitoring and evaluation of the effect of photodynamic treatment on live cells in vitro is presented. Variations in morphological characteristics of cells in the course and after treatment are recorded by means of digital holographic microscopy. High-precision measurements of phase shift gained by probe radiation in HeLa and human endometrial mesenchymal stem cell cultures demonstrate for the first time changes of their volume occurred in response to treatment.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

We obtained the characteristics of late cell death occurrence and talaporfin sodium uptake to myocardial cell with various incubation times with talaporfin sodium.

Fluorescence in neurosurgery: Its diagnostic and therapeutic use. Review of the literature

Fluorescent agents, e.g. 5-aminolevulinic acid (5-ALA), fluorescein and indocyanine green (ICG) are in common use in neurosurgery for tumor resection and neurovascular surgery. Protoporphyrine IX (PPIX) as major metabolite of 5-ALA is a strong fluorescent substance accumulated within malignant glioma tissue and a very sensitive and specific tool for visualizing high grade glioma tissue during surgery. Furthermore, 5-ALA or rather PPIX also offers an intratumoral therapeutic option stimulated by laser light in specific wavelength. Fluorescein was demonstrated to show similar fluorescent reactions in neurosurgery, but is controversial in its use, especially in high grade tumor surgery. Intraoperative angiography during resection of arterio-venous malformations, extracranial-intracranial-bypass or aneurysm surgery is supported by ICG fluorescence. Generally ICG will provide beneficial information for both, exposure of the pathology and illustration of healthy structures. This manuscript shows an overview of the literature focussing fluorescence in neurosurgery.

ASYMMETRIC CELL DIVISION: IMPLICATIONS FOR GLIOMA DEVELOPMENT AND TREATMENT

Glioma is a heterogeneous disease process with differential histology and treatment response. It was previously thought that the histological features of glial tumors indicated their cell of origin. However, the discovery of continuous neuro-gliogenesis in the normal adult brain and the identification of brain tumor stem cells within glioma have led to the hypothesis that these brain tumors originate from multipotent neural stem or progenitor cells, which primarily divide asymmetrically during the postnatal period. Asymmetric cell division allows these cell types to concurrently self-renew whilst also producing cells for the differentiation pathway. It has recently been shown that increased symmetrical cell division, favoring the self-renewal pathway, leads to oligodendroglioma formation from oligodendrocyte progenitor cells. In contrast, there is some evidence that asymmetric cell division maintenance in tumor stem-like cells within astrocytoma may lead to acquisition of treatment resistance. Therefore cell division mode in normal brain stem and progenitor cells may play a role in setting tumorigenic potential and the type of tumor formed. Moreover, heterogeneous tumor cell populations and their respective cell division mode may confer differential sensitivity to therapy. This review aims to shed light on the controllers of cell division mode which may be therapeutically targeted to prevent glioma formation and improve treatment response.

In vitro investigation of efficient photodynamic therapy using a nonviral vector; hemagglutinating virus of Japan envelope

Photodynamic therapy (PDT) is a photochemical modality approved for cancer treatment. PDT has demonstrated efficacy in early stage lung cancer and esophageal cancer. The accumulation of photosensitizers in cancer cells is necessary to enhance the therapeutic benefits of PDT; however, photosensitizers have low uptake efficiency. To overcome this limitation, a drug delivery system, such as the hemagglutinating virus of Japan envelope (HVJ-E) vector, is required. In this study, the combination of PDT and HVJ-E was investigated for enhancing the efficacy of PDT. The photosensitizers that were evaluated included 5-aminolaevulinic acid (5-ALA), protoporphyrin IX (PPIX), and HVJ-PPIX. The uptake of the photosensitizers as increased twenty-fold with the addition of HVJ-E. The cytotoxicity of conventional 5-ALA was enhanced by the addition of HVJ-E vector. In conclusion, HVJ-E vector improved the uptake of photosensitizers and the PDT effect.

In vitro investigation of efficient photodynamic therapy using a nonviral vector; hemagglutinating virus of Japan envelope

Photodynamic therapy (PDT) is a photochemical modality approved for cancer treatment. PDT has demonstrated efficacy in early stage lung cancer and esophageal cancer. The accumulation of photosensitizers in cancer cells is necessary to enhance the therapeutic benefits of PDT; however, photosensitizers have low uptake efficiency. To overcome this limitation, a drug delivery system, such as the hemagglutinating virus of Japan envelope (HVJ-E) vector, is required. In this study, the combination of PDT and HVJ-E was investigated for enhancing the efficacy of PDT. The photosensitizers that were evaluated included 5-aminolaevulinic acid (5-ALA), protoporphyrin IX (PPIX), and HVJ-PPIX. The uptake of the photosensitizers as increased twenty-fold with the addition of HVJ-E. The cytotoxicity of conventional 5-ALA was enhanced by the addition of HVJ-E vector. In conclusion, HVJ-E vector improved the uptake of photosensitizers and the PDT effect.

Photodynamic therapy of Pheophorbide a inhibits the proliferation of human breast tumour via both caspase-dependent and -independent apoptotic pathways in in vitro and in vivo models

Breast cancer is conventionally treated by surgery and radiotherapy, with adjuvant chemotherapy and hormonotherapy as supplementary treatments. However, such treatments are associated with adverse side effects and drug resistance. In this study, Pheophorbide a (Pa), a photosensitizer isolated from Scutelleria barbata, was analysed for its antiproliferative effect on human breast tumour cells. The IC (inhibitory concentration)(50) of the combined treatment of Pa and photodynamic therapy (Pa-PDT) on human breast tumour MCF-7 cells was 0.5 µm. Mechanistic studies in MCF-7 cells demonstrated that Pa was localized in the mitochondria, and reactive oxygen species were found to be released after Pa-PDT. Apoptosis was the major mechanism responsible for the tumour cell death, and mitochondrial membrane depolarization and cytochrome c release highlighted the role of mitochondria in the apoptotic mechanism. Up-regulation of tumour suppressor protein p53, cleavage of caspase-9 and poly (ADP-ribose) polymerase suggested that the caspase-dependent pathway was induced, while the release of apoptosis-inducing factors demonstrated that the apoptosis was also mediated by the caspase-independent mechanism. In vivo study using the mouse xenograft model showed a significant inhibition of MCF-7 tumour growth by Pa-PDT. Together, the results of this study provide a basis for understanding and developing Pa-PDT as a cure for breast cancer.

Solvatochromic and fluorescence behavior of sulfisoxazole

The Fluorescence spectroscopic and solvatochromic behavior of Sulfisoxazole, a sulfa drug with antimicrobial activities, in various pure solvents of different polarity and hydrogen bonding capability is reported. The fluorescence emission spectrum of sulfisoxazole was found to be solvent polarity dependent, where a notable red shift in emission maximum was observed with increasing solvent polarity as well as hydrogen bonding capability. The effects of the latter two solvent parameters were quantitatively investigated using the methods of Lippert-Mataga and solvatochromic comparison method (SCM) that is based on the Kamlet-Taft equation. Particularly, the Lippert-Mataga method was applied to estimate the dipole moment of the excited state (μ(e)) upon plotting Stokes shift versus solvent polarizability (Δf), where a value of 11.54 Debye was obtained. On the other hand, applying the multiple regression analysis to the SCM method revealed that solvent polarizability (π*) and hydrogen-bond donor capability (α) approximately equally stabilize sulfisoxazole in the excited state with minor destabilization contribution by the hydrogen-bond acceptor capability (β). These findings revealed that the excited state of sulfisoxazole is stabilized by polar solvents, indicating that this drug molecules exhibit larger dipole moment in the excited state than in the ground state, which in turn implies that a potential intramolecular charge transfer (ICT) occurs after excitation.

Evaluation of oxygen consumption of culture medium and in vitro photodynamic effect of talaporfin sodium in lung tumor cells

OBJECTIVE

Successful photodynamic therapy (PDT) requires high production of radical ions and singlet oxygen to kill target cells. However, PDT also induces angiogenesis through production of vascular endothelial growth factor (VEGF), which promotes cell regrowth and vascularization. In this study, we evaluated the importance of oxygen in PDT by measuring oxygen consumption, photosensitizer bleaching, and reactive oxygen species (ROS) production in the culture medium, and VEGF secretion either during or after PDT treatment using mouse Lewis lung carcinoma (LLC) cells.

BACKGROUND DATA

Local hypoxia is induced under a low oxygen environment. Oxygen is consumed when ROS and singlet oxygen are produced during PDT. The effect of oxygen consumption on cytotoxicity and VEGF secretion has not been clarified.

MATERIALS AND METHODS

Mouse Lewis lung carcinoma (LLC) cells treated with the photosensitizer talaporfin sodium were irradiated by a continuous wave semiconductor laser (wavelength, 664 +/- 1 nm). We used oxygen microelectrode for oxygen measurement, a fluorescent probe to detect ROS, MTT assay to evaluate the PDT efficacy, and enzyme-linked immunosorbent assay to measure VEGF concentration.

RESULTS

During PDT, oxygen consumption was higher with high doses of talaporfin sodium solution compared with low doses. In addition, the fluorescence of 2-[6-(4'-amino)phenoxy-3H-xanthen-3-on-9-yl]benzoic acid, a probe for highly reactive oxygen species such as hydroxyl radicals (*OH), dramatically increased when the dose of talaporfin sodium solution was high. Moreover, VEGF concentration increased after PDT due to hypoxia in a manner dependent on photosensitizer concentration.

CONCLUSION

These results indicate that the efficiency of PDT might be improved by sustaining a replete oxygen environment during PDT, not only for ROS and singlet oxygen production, but also for inhibiting neoangiogenesis.

Photodynamic therapy induces microRNA-210 and -296 expression in HeLa cells

Apoptosis-related microRNAs (miRNAs), the expression levels of which were observed to increase after photodynamic therapy (PDT), were identified as markers of PDT efficacy. miRNAs form a class of small endogenous RNAs that play important regulatory roles by targeting mRNA for cleavage or translational repression. miRNAs contribute to diverse biological processes, including development, cell growth, apoptosis, and hematopoiesis, which suggests a role in cancer development. However, no previous reports have described a relationship between apoptosis and miRNA expression after PDT. In this study, apoptosis-related miRNA levels were characterized by real-time PCR after PDT in HeLa cells. miR-210 and miR-296 expression levels increased 1 hour after PDT, although the other apoptosis-related miRNA (miR-7, miR-148a, miR-204, and miR-216) expression levels were unchanged. Since miR-210 is the most prominent miRNA consistently stimulated under hypoxic conditions and VEGF is capable of increasing miR-296 expression levels, these data suggest that hypoxia induced by PDT induces miR-210 expression, followed by an increase of VEGF expression and miR-296 expression. These results constitute the first report of an analysis of miRNA expression after PDT using talaporfin sodium as a photosensitizer, demonstrating that miR-210 and miR-296 expression levels are markers of PDT efficacy in HeLa cells.

Chondrogenic mRNA expression in prechondrogenic cells after blue laser irradiation

Low-level laser therapy (LLLT) has been used as a method for biostimulation. Cartilage develops through the differentiation of mesenchymal cells into chondrocytes, and differentiated chondrocytes in articular cartilage maintain cartilage homeostasis by synthesizing cartilage-specific extracellular matrix. The aim of this study is to evaluate the enhancement of chondrocyte differentiation and the expression levels of chondrogenic mRNA in prechondrogenic ATDC5 cells after laser irradiation. For chondrogenic induction, ATDC5 cells were irradiated with a blue laser (405 nm, continuous wave) at 100 mW/cm(2) for 180 s following incubation in chondrogenic differentiation medium. Differentiation after laser irradiation was quantitatively evaluated by the measurement of total collagen contents and chondrogenesis-related mRNAs. The total amount of collagen and mRNA levels of aggrecan, collagen type II, SOX-9, and DEC-1 were increased relative to those of a non-laser irradiated group after 14 days of laser irradiation. On the other hand, Ap-2alpha mRNA, a negative transcription factor of chondrogenesis, was dramatically decreased after laser irradiation. In addition, intracellular reactive oxygen species (ROS) were generated after laser irradiation. These results, for the first time, provide functional evidence that mRNA expression relating to chondrogenesis is increased, and Ap-2alpha is decreased immediately after laser irradiation. As this technique could readily be applied in situ to control the differentiation of cells at an implanted site within the body, this approach may have therapeutic potential for the restoration of damaged or diseased tissue.