Photodynamic Effects of ZnPcS4-BSA in Human Retinal Pigment Epithelium Cells

Retinal debris triggers cytotoxic damage in cocultivated primary porcine RPE cells

Introduction

One of the most common causes of vision loss in the elderly population worldwide is age-related macular degeneration (AMD). Subsequently, the number of people affected by AMD is estimated to reach approximately 288 million by the year 2040. The aim of this study was to develop an ex vivo model that simulates various aspects of the complex AMD pathogenesis.

Methods

For this purpose, primary porcine retinal pigment epithelial cells (ppRPE) were isolated and cultured. One group was exposed to medium containing sodium iodate (NaIO3) to induce degeneration. The others were exposed to different supplemented media, such as bovine serum albumin (BSA), homogenized porcine retinas (HPR), or rod outer segments (ROOS) for eight days to promote retinal deposits. Then, these ppRPE cells were cocultured with porcine neuroretina explants for another eight days. To assess the viability of ppRPE cells, live/dead assay was performed at the end of the study. The positive RPE65 and ZO1 area was evaluated by immunocytochemistry and the expression of RLBP1, RPE65, and TJP1 was analyzed by RT-qPCR. Additionally, drusen (APOE), inflammation (ITGAM, IL6, IL8, NLRP3, TNF), oxidative stress (NFE2L2, SOD1, SOD2), and hypoxia (HIF1A) markers were investigated. The concentration of the inflammatory cytokines IL-6 and IL-8 was determined in medium supernatants from day 16 and 24 via ELISA.

Results

Live/dead assay suggests that especially exposure to NaIO3 and HPR induced damage to ppRPE cells, leading in a significant ppRPE cell loss. All supplemented media resulted in decreased RPE-characteristic markers (RPE65; ZO-1) and gene expression like RLBP1 and RPE65 in the cultured ppRPE cells. Besides, some inflammatory, oxidative as well as hypoxic stress markers were altered in ppRPE cells cultivated with NaIO3. The application of HPR induced an enhanced APOE expression. Pre-exposure of the ppRPE cells led to a diminished number of cones in all supplemented media groups compared to controls.

Discussion

Overall, this novel coculture model represents an interesting initial approach to incorporating deposits into coculture to mimic AMD pathogenesis. Nevertheless, the effects of the media used need to be investigated in further studies.

Label-free detection of hydrogen peroxide-induced oxidative stress in human retinal pigment epithelium cells via laser tweezers Raman spectroscopy

Human retinal pigment epithelium cells under hydrogen peroxide-induced oxidative stress and a ligustrazine-based protective effect were investigated using laser tweezers Raman spectroscopy. Protein and lipid were significantly affected by oxidative damage, along with increased reactive oxygen species (ROS) level within cells. The effects of ligustrazine against the reaction of ROS with protein seemed to be able to inhibit such damages but were limited during the desamidization of amides, along with additional effect on nucleic acid base and DNA phosphoric acid skeleton. This work laid the basis for both understanding the molecular mechanisms of oxidative stress-induced injury and highlighting possible biomarkers in retinal diseases.

Intermolecular interaction of nickel (ii) phthalocyanine tetrasulfonic acid tetrasodium salt with bovine serum albumin: A multi-technique study

The interaction of nickel (II) phthalocyanine tetrasulfonic acid tetrasodium salt with bovine serum albumin (BSA) has been investigated by combination of fluorescence, UV-vis absorption, Fourier transform infrared (FT-IR), and circular dichorism (CD) spectroscopies as well as through molecular docking. Fluorescence quenching and absorption spectra were investigated as a mean for estimating the binding parameters. Analysis of fluorescence quenching data at different temperatures was performed in order to specify the thermodynamics parameters for interactions of phthalocyanine complex with BSA. According to experimental data it was suggested that phthalocyanine had a significant binding affinity to BSA and the process was entropy driven. Based on the results of molecular docking it was indicated that the main active binding site for this phthalocyanine complex is site I in subdomain IIA of BSA. The results provide useful information for understanding the binding mechanism of anticancer drug-albumin and gives insight into the biological activity and metabolism of the drug in blood.

Enhancement of the photokilling effect of aluminum phthalocyanine in photodynamic therapy by conjugating with nitrogen-doped TiO2 nanoparticles

As a second-generation photodynamic therapy (PDT) photosensitizer, aluminum phthalocyanine chloride tetrasulfonate (Pc) has gained great attention due to its high absorption at the red light region. Yet, its application in PDT is strongly limited by its low cellular uptake efficiency. In this report, nitrogen-doped TiO2 nanoparticles (N-TiO2) conjugated with Pc are synthesized by a two-step surface modification method. The N-TiO2-Pc products are characterized by Zeta potential, transmission electron microscopy and UV-vis absorption spectroscopy. The cellular uptake, intracellular distribution, cytotoxicity and the photokilling effect of the nanoparticles are studied on different cancer cell lines. Compared with Pc, the absorption spectrum of N-TiO2-Pc expands from red to UV region, resulting in a higher production of reactive oxygen species under visible light irradiation. In addition, the cellular uptake of Pc is largely improved by its carrier N-TiO2. The photokilling efficiency of N-TiO2-Pc is over ten times higher than that of Pc. The results suggest that N-TiO2-Pc is an excellent candidate as a photosensitizer in PDT.

Tetra-sulfonate phthalocyanine zinc-bovine serum albumin conjugate-mediated photodynamic therapy of human glioma

Background

Glioma is the most common brain malignancy with poor prognosis. The current treatments for gliomas are mainly based on surgery, chemotherapy, and radiotherapy, which exhibit limited efficacy. Photodynamic therapy (PDT) using photosensitizers has been applied to glioma therapy. However, different photosensitizers usually lead to different therapeutic effects and adverse reactions.

Objective

This study investigates the anti-tumor effect of photosensitizer ZnPcS4-BSA in xenograft glioma tumors.

Methods

The xenograft glioma tumor model was established by inoculating nude mice with U251 cells. Tumor growth was evaluated by tumor volume, weight, and inhibition rate. Cell apoptosis was evaluated using TUNEL staining. Vascular endothelial growth factor (VEGF) expression and microvessel density were measured by immunohistochemistry.

Results

Significant decreases in tumor volume and weight as well as significant increases in tumor inhibition rate, cell apoptosis, VEGF expression, and microvessel density were observed in mice in the low- and high-dose PDT groups compared to the control, irradiation alone, and photosensitizer alone groups. No significant difference in cytotoxicity was observed between control group and photosensitizer alone group. Photosensitizer ZnPcS4-BSA significantly inhibited xenograft glioma tumor growth through induction of apoptosis.

Conclusion

PDT using ZnPcS4-BSA may be effective for the therapy of gliomas.