Optical clearing agent increases effectiveness of photodynamic therapy in a mouse model of cutaneous melanoma: an analysis by Raman microspectroscopy

Advances and perspectives in use of semisolid formulations for photodynamic methods

Although nearly 30 years have passed since the introduction of the first clinically approved photosensitizer for photodynamic therapy, progress in developing new pharmaceutical formulations remains unsatisfactory. This review highlights that despite years of research, many recurring challenges and issues remain unresolved. The paper includes an analysis of selected essential studies involving aminolevulinic acid and its derivatives, as well as other photosensitizers with potential for development as medical products. Among various possible vehicles, special attention is given to gelatin, alginates, poly(ethylene oxide), polyacrylic acid, and chitosan. The focus is particularly on infectious and cancerous diseases. Key aspects of developing new semi-solid drug forms should prioritize the creation of easily manufacturable and biocompatible preparations for clinical use. At the same time, new formulations should preserve the primary function of photosensitizers, which is the generation of reactive oxygen species capable of destroying pathogenic cells or tumors. Additionally, the use of adjuvant properties of carriers, which can enhance the effectiveness of macrocycles, is emphasized, especially in chitosan-based antibacterial formulations. Current research indicates that many promising dyes and macrocyclic compounds with high potential as photosensitizers in photodynamic therapy remain unexplored in formulation and development work. This review outlines potential new and previously explored pathways for advancing photosensitizers as active pharmaceutical ingredients (APIs).

Optical tissue clearing associated with 3D imaging: application in preclinical and clinical studies

Understanding the inner morphology of intact tissues is one of the most competitive challenges in modern biology. Since the beginning of the twentieth century, optical tissue clearing (OTC) has provided solutions for volumetric imaging, allowing the microscopic visualization of thick sections of tissue, organoids, up to whole organs and organisms (for example, mouse or rat). Recently, tissue clearing has also been introduced in clinical settings to achieve a more accurate diagnosis with the support of 3D imaging. This review aims to give an overview of the most recent developments in OTC and 3D imaging and to illustrate their role in the field of medical diagnosis, with a specific focus on clinical applications.

Optical clearing of tissues: Issues of antimicrobial phototherapy and drug delivery

This review presents principles and novelties in the field of tissue optical clearing (TOC) technology, as well as application for optical monitoring of drug delivery and effective antimicrobial phototherapy. TOC is based on altering the optical properties of tissue through the introduction of immersion optical cleaning agents (OCA), which impregnate the tissue of interest. We also analyze various methods and kinetics of delivery of photodynamic agents, nanoantibiotics and their mixtures with OCAs into the tissue depth in the context of antimicrobial and antifungal phototherapy. In vitro and in vivo studies of antimicrobial phototherapies, such as photodynamic, photothermal plasmonic and photocatalytic, are summarized, and the prospects of a new TOC technology for effective killing of pathogens are discussed.

3D models of the dynamics of cancer cells under external pressure

Skin cancer is one of the most frequent cancers worldwide. Recently, it has been shown that the tumor proliferation rate in skin and its dynamics can be changed by an osmotic pressure. However, these findings are rather unstructured. A weak pressure can slow down the tumor growth, while a very high pressure can, on the contrary, lead to accelerated growth and metastases. The magnitude and spatial distribution of osmotic pressures in tumors at present cannot be measured experimentally. Therefore, it is of particular interest to find appropriate models that would simulate the effects of additional osmotic pressures in skin and assess the features of its implementation. In this paper, we suggest an improved model based on the principles of the conventional hydrodynamic model for macrophase separations, which allows one to include not only the properties of healthy and cancer cells but also the microenvironment. We study and analyze the proliferation of cancer cells in 3D models of the epidermal layer of skin under an osmotic pressure. There are two suggested 3D models that are based on the same principles: (1) cellular cubic lattice and (2) cell spheroid. This allows expanding the application of the model depending on a given task. Here, we are focused on the study of melanoma at an early stage when there are not many cancer cells. Additional compressive and expansive pressures are added to the central part of the system. Both systems demonstrate similar results in slowing down the rate of tumor growth with a small pressure.

Photodynamic therapy reduces metastasis of breast cancer by minimizing circulating tumor cells

Cancer metastasis after traditional surgery introduces a high barrier to therapy efficacy. Photodynamic therapy (PDT) for cancer is based on a photochemical process of photosensitizers that concentrate in tumors and release oxidant species under light excitation to destroy cells. Compared with traditional surgery, PDT provides minimal invasion and targeted therapy. In this in vivo study, we monitor the real-time and long-term dynamics of circulating tumor cells (CTCs) after a single round of PDT and after surgical resection in a breast cancer animal model. The CTC level is low after PDT treatment, and the recurrence of the primary tumor is postponed in the PDT group compared with the resection group. We find that metastasis is correlated with the CTC level, and the PDT-treated mice show no metastasis in the lung or liver. Our results suggest PDT can effectively reduce metastasis by minimizing CTCs after treatment and is a great technology for breast cancer therapy.