Modeling Epidermal Growth Factor Inhibitor-mediated Enhancement of Photodynamic Therapy Efficacy Using 3D Mesothelioma Cell Culture

Establishment of an experimental model of canine malignant mesothelioma organoid culture using a three-dimensional culture method

Canine malignant mesothelioma (cMM) is a rare and drug-resistant malignant tumor. Due to few patients and experimental models, there have not been enough studies to demonstrate the pathogenesis of the disease and novel effective treatment for cMM. Since cMM resembles human MM (hMM) in histopathological characteristics, it is also considered a promising research model of hMM. Compared with conventional 2-dimensional (2D) culture methods, 3-dimensional (3D) organoid culture can recapitulate the properties of original tumor tissues. However, cMM organoids have never been developed. In the present study, we for the first time generated cMM organoids using the pleural effusion samples. Organoids from individual MM dogs were successfully generated. They exhibited the characteristics of MM and expressed mesothelial cell markers, such as WT-1 and mesothelin. The sensitivity to anti-cancer drugs was different in each strain of cMM organoids. RNA sequencing analysis showed cell adhesion molecule pathways were specifically upregulated in cMM organoids compared with their corresponding 2D cultured cells. Among these genes, the expression level of E-cadherin was drastically higher in the organoids than that in the 2D cells. In conclusion, our established cMM organoids might become a new experimental tool to provide new insights into canine and human MM therapy.

Tissue Engineering and Photodynamic Therapy: A New Frontier of Science for Clinical Application -An Up-To-Date Review

Tissue engineering (TE) connects principles of life sciences and engineering to develop biomaterials as alternatives to biological systems and substitutes that can improve and restore tissue function. The principle of TE is the incorporation of cells through a 3D matrix support (scaffold) or using scaffold-free organoid cultures to reproduce the 3D structure. In addition, 3D models developed can be used for different purposes, from studies mimicking healthy tissues and organs as well as to simulate and study different pathologies. Photodynamic therapy (PDT) is a non-invasive therapeutic modality when compared to conventional therapies. Therefore, PDT has great acceptance among patients and proves to be quite efficient due to its selectivity, versatility and therapeutic simplicity. The PDT mechanism consists of the use of three components: a molecule with higher molar extinction coefficient at UV-visible spectra denominated photosensitizer (PS), a monochromatic light source (LASER or LED) and molecular oxygen present in the microenvironment. The association of these components leads to a series of photoreactions and production of ultra-reactive singlet oxygen and reactive oxygen species (ROS). These species in contact with the pathogenic cell, leads to its target death based on necrotic and apoptosis ways. The initial objective of PDT is the production of high concentrations of ROS in order to provoke cellular damage by necrosis or apoptosis. However, recent studies have shown that by decreasing the energy density and consequently reducing the production of ROS, it enabled a specific cell response to photostimulation, tissues and/or organs. Thus, in the present review we highlight the main 3D models involved in TE and PS most used in PDT, as well as the applications, future perspectives and limitations that accompany the techniques aimed at clinical use.

In vivo Tissue Evaluation Reveals Improvements in Explicit PDT Dosimetry

Progress is needed before explicit photodynamic therapy (PDT) dosimetry can treat peritoneal carcinomatosis and yet spare all healthy tissue. A report by Cengel et al. in this issue of Photochemistry & Photobiology on tissue evaluation in a canine model may bring that goal a step closer and may even be dogma-changing.

In Vitro Characterization of Cisplatin and Pemetrexed Effects in Malignant Pleural Mesothelioma 3D Culture Phenotypes

Malignant pleural mesothelioma (MPM) is an aggressive cancer with poor prognosis. The main treatment for MPM is doublet chemotherapy with Cisplatin and Pemetrexed, while ongoing trials test the efficacy of pemetrexed monotherapy. However, there is lack of evidence regarding the effects of Cisplatin and Pemetrexed on MPM cell phenotypes, especially in three-dimensional (3D) cell cultures. In this study, we evaluated the effects Cisplatin and Pemetrexed on cell viability using homologous cell derived extracellular matrix (hECM) as substratum and subsequently in the following 3D cell culture phenotypes: tumor spheroid formation, tumor spheroid invasion, and collagen gel contraction. We used benign mesothelial MeT-5A cells as controls and the MPM cell lines M14K (epithelioid), MSTO (biphasic), and ZL34 (sarcomatoid). Cell viability of all cell lines was significantly decreased with all treatments. Mean tumor spheroid perimeter was reduced after treatment with Pemetrexed or the doublet therapy in all cell lines, while Cisplatin reduced the mean spheroid perimeter of MeT-5A and MSTO cells. Doublet treatment reduced the invasive capacity of spheroids of cell lines into collagenous matrices, while Cisplatin lowered the invasion of the MSTO and ZL34 cell lines, and Pemetrexed lowered the invasion of MeT-5A and ZL34 cell lines. Treatment with Pemetrexed or the combination significantly reduced the collagen gel contraction of all cell lines, while Cisplatin treatment affected only the MeT-5A and M14K cells. The results of the current study can be used as an in vitro 3D platform for testing novel drugs against MPM for ameliorating the effects of first line chemotherapeutics.

Chitosan-Based Drug Delivery Systems for Optimization of Photodynamic Therapy: a Review

Drug delivery systems (DDS) can be designed to enrich the pharmacological and therapeutic properties of several drugs. Many of the initial obstacles that impeded the clinical applications of conventional DDS have been overcome with nanotechnology-based DDS, especially those formed by chitosan (CS). CS is a linear polysaccharide obtained by the deacetylation of chitin, which has potential properties such as biocompatibility, hydrophilicity, biodegradability, non-toxicity, high bioavailability, simplicity of modification, aqueous solubility, and excellent chemical resistance. Furthermore, CS can prepare several DDS as films, gels, nanoparticles, and microparticles to improve delivery of drugs, such as photosensitizers (PS). Thus, CS-based DDS are broadly investigated for photodynamic therapy (PDT) of cancer and fungal and bacterial diseases. In PDT, a PS is activated by light of a specific wavelength, which provokes selective damage to the target tissue and its surrounding vasculature, but most PS have low water solubility and cutaneous photosensitivity impairing the clinical use of PDT. Based on this, the application of nanotechnology using chitosan-based DDS in PDT may offer great possibilities in the treatment of diseases. Therefore, this review presents numerous applications of chitosan-based DDS in order to improve the PDT for cancer and fungal and bacterial diseases.