Dual-Agent Photodynamic Therapy with Optical Clearing Eradicates Pigmented Melanoma in Preclinical Tumor Models

Melatonin/Sericin Wound Healing Patches: Implications for Melanoma Therapy

Melatonin and sericin exhibit antioxidant properties and may be useful in topical wound healing patches by maintaining redox balance, cell integrity, and regulating the inflammatory response. In human skin, melatonin suppresses damage caused by ultraviolet radiation (UVR) which involves numerous mechanisms associated with reactive oxygen species/reactive nitrogen species (ROS/RNS) generation and enhancing apoptosis. Sericin is a protein mainly composed of glycine, serine, aspartic acid, and threonine amino acids removed from the silkworm cocoon (particularly Bombyx mori and other species). It is of interest because of its biodegradability, anti-oxidative, and anti-bacterial properties. Sericin inhibits tyrosinase activity and promotes cell proliferation that can be supportive and useful in melanoma treatment. In recent years, wound healing patches containing sericin and melatonin individually have attracted significant attention by the scientific community. In this review, we summarize the state of innovation of such patches during 2021-2023. To date, melatonin/sericin-polymer patches for application in post-operational wound healing treatment has been only sparingly investigated and it is an imperative to consider these materials as a promising approach targeting for skin tissue engineering or regenerative dermatology.

Femtosecond pulsed laser photodynamic therapy activates melanin and eradicates malignant melanoma

Photodynamic therapy (PDT) relies on a series of photophysical and photochemical reactions leading to cell death. While effective for various cancers, PDT has been less successful in treating pigmented melanoma due to high light absorption by melanin. Here, this limitation is addressed by 2-photon excitation of the photosensitizer (2p-PDT) using ~100 fs pulses of near-infrared laser light. A critical role of melanin in enabling rather than hindering 2p-PDT is elucidated using pigmented and non-pigmented murine melanoma clonal cell lines in vitro. The photocytotoxicities were compared between a clinical photosensitizer (Visudyne) and a porphyrin dimer (Oxdime) with ~600-fold higher σ2p value. Unexpectedly, while the 1p-PDT responses are similar in both cell lines, 2p activation is much more effective in killing pigmented than non-pigmented cells, suggesting a dominant role of melanin 2p-PDT. The potential for clinical translational is demonstrated in a conjunctival melanoma model in vivo, where complete eradication of small tumors was achieved. This work elucidates the melanin contribution in multi-photon PDT enabling significant advancement of light-based treatments that have previously been considered unsuitable in pigmented tumors.

Conditions of acceleration and deceleration of the cancer cell growth under osmotic pressure

In this paper, we study a pattern formation in the epidermal layer of skin during tumor development and appearance of a binary surface consisting of healthy and cancer cells forming Turing patterns under external osmotic pressure. The basic methodology of introducing the external influences, for example, time-targeted drug therapy or radiation exposure, influence of electromagnetic fields, laser radiation or other tumor-targeting physical influences act differently in different phases of the cell cycle. In some cases, this can lead to a slowdown in the growth of cancer cells, and sometimes vice versa. Therefore, it is of particular interest to choose the right parameters such as starting time of external pressure, its magnitude and duration depending on the cell cycle of developing cancer cells. We propose a biologically inspired model that allows us to simulate the growth of cancer cells under conditions of osmotic pressure. We divide this growth into two phases. The first is characterized by active cell division, and the second by their growth. In this article, we introduce two types of pressure: short-term and long-term, and looked at what this leads to in different phases. We have found an interesting result, that there are some resonant points in time both in the first and second phases, when the introduction of additional pressure leads to the most significant slowdown in the growth of cancer cells.

Photoacoustic imaging for cutaneous melanoma assessment: a comprehensive review

Significance

Cutaneous melanoma (CM) has a high morbidity and mortality rate, but it can be cured if the primary lesion is detected and treated at an early stage. Imaging techniques such as photoacoustic (PA) imaging (PAI) have been studied and implemented to aid in the detection and diagnosis of CM.

Aim

Provide an overview of different PAI systems and applications for the study of CM, including the determination of tumor depth/thickness, cancer-related angiogenesis, metastases to lymph nodes, circulating tumor cells (CTCs), virtual histology, and studies using exogenous contrast agents.

Approach

A systematic review and classification of different PAI configurations was conducted based on their specific applications for melanoma detection. This review encompasses animal and preclinical studies, offering insights into the future potential of PAI in melanoma diagnosis in the clinic.

Results

PAI holds great clinical potential as a noninvasive technique for melanoma detection and disease management. PA microscopy has predominantly been used to image and study angiogenesis surrounding tumors and provide information on tumor characteristics. Additionally, PA tomography, with its increased penetration depth, has demonstrated its ability to assess melanoma thickness. Both modalities have shown promise in detecting metastases to lymph nodes and CTCs, and an all-optical implementation has been developed to perform virtual histology analyses. Animal and human studies have successfully shown the capability of PAI to detect, visualize, classify, and stage CM.

Conclusions

PAI is a promising technique for assessing the status of the skin without a surgical procedure. The capability of the modality to image microvasculature, visualize tumor boundaries, detect metastases in lymph nodes, perform fast and label-free histology, and identify CTCs could aid in the early diagnosis and classification of CM, including determination of metastatic status. In addition, it could be useful for monitoring treatment efficacy noninvasively.

Combination of Two Photosensitisers in Anticancer, Antimicrobial and Upconversion Photodynamic Therapy

Photodynamic therapy (PDT) is a special form of phototherapy in which oxygen is needed, in addition to light and a drug called a photosensitiser (PS), to create cytotoxic species that can destroy cancer cells and various pathogens. PDT is often used in combination with other antitumor and antimicrobial therapies to sensitise cells to other agents, minimise the risk of resistance and improve overall outcomes. Furthermore, the aim of combining two photosensitising agents in PDT is to overcome the shortcomings of the monotherapeutic approach and the limitations of individual agents, as well as to achieve synergistic or additive effects, which allows the administration of PSs in lower concentrations, consequently reducing dark toxicity and preventing skin photosensitivity. The most common strategies in anticancer PDT use two PSs to combine the targeting of different organelles and cell-death mechanisms and, in addition to cancer cells, simultaneously target tumour vasculature and induce immune responses. The use of PDT with upconversion nanoparticles is a promising approach to the treatment of deep tissues and the goal of using two PSs is to improve drug loading and singlet oxygen production. In antimicrobial PDT, two PSs are often combined to generate various reactive oxygen species through both Type I and Type II processes.

Skin optical clearing enabled by dissolving hyaluronic acid microneedle patches

Optical imaging and phototherapy are of great significance in the detection, diagnosis, and therapy of diseases. Depth of light in the skin tissues in optical imaging and phototherapy can be significantly improved with the assistance of optical clearing technology by weakening the scattering from the refractive indexes inhomogeneity among skin constituents. However, the barrier of the stratum corneum restricts the penetration of optical clearing agents into deep tissues and limits the optical clearing effects. Herein, we develop an optical clearing strategy by using dissolving microneedle (MN) patches made of hyaluronic acid (HA), which can effortlessly and painlessly penetrate the stratum corneum to reach the epidermis and dermis. By using the HA MN patches, the transmittance of skin tissues is improved by about 12.13 %. We show that the HA MN patches enhance the clarity of blood vessels to realize naked-eyes observation. Moreover, a simulated subcutaneous tumor cells experiment also verifies that the optical clearing effects of the HA MN patch efficiently boost the efficiency of the photodynamic killing of tumor cells by 26.8 %. As a courageous attempt, this study provides a promising avenue to improve the optical clearing effects for further clinical application of optical imaging and phototherapy.

Binary dose level classification of tumour microvascular response to radiotherapy using artificial intelligence analysis of optical coherence tomography images

The dominant consequence of irradiating biological systems is cellular damage, yet microvascular damage begins to assume an increasingly important role as the radiation dose levels increase. This is currently becoming more relevant in radiation medicine with its pivot towards higher-dose-per-fraction/fewer fractions treatment paradigm (e.g., stereotactic body radiotherapy (SBRT)). We have thus developed a 3D preclinical imaging platform based on speckle-variance optical coherence tomography (svOCT) for longitudinal monitoring of tumour microvascular radiation responses in vivo. Here we present an artificial intelligence (AI) approach to analyze the resultant microvascular data. In this initial study, we show that AI can successfully classify SBRT-relevant clinical radiation dose levels at multiple timepoints (t = 2–4 weeks) following irradiation (10 Gy and 30 Gy cohorts) based on induced changes in the detected microvascular networks. Practicality of the obtained results, challenges associated with modest number of animals, their successful mitigation via augmented data approaches, and advantages of using 3D deep learning methodologies, are discussed. Extension of this encouraging initial study to longitudinal AI-based time-series analysis for treatment outcome predictions at finer dose level gradations is envisioned.

Targeting Microenvironment of Melanoma and Head and Neck Cancers in Photodynamic Therapy

Background:

Photodynamic therapy (PDT), in comparison to other skin cancers, is still far less effective for melanoma, due to the strong absorbance and the role of melanin in cytoprotection. The tumour microenvironment (TME) has a significant role in tumour progression, and the hypoxic TME is one of the main reasons for melanoma progression to metastasis and its resistance to PDT. Hypoxia is also a feature of solid tumours in the head and neck region that indicates negative prognosis.

Objective:

The aim of this study was to individuate and describe systematically the main strategies in targeting the TME, especially hypoxia, in PDT against melanoma and head and neck cancers (HNC), and assess the current success in their application.

Methods:

PubMed was used for searching, in MEDLINE and other databases, for the most recent publications on PDT against melanoma and HNC in combination with the TME targeting and hypoxia.

Results:

In PDT for melanoma and HNC, it is very important to control hypoxia levels, and amongst the different approaches, oxygen self-supply systems are often applied. Vascular targeting is promising, but to improve it, optimal drug-light interval, and formulation to increase the accumulation of the photosensitiser in the tumour vasculature, have to be established. On the other side, the use of angiogenesis inhibitors, such as those interfering with VEGF signalling, is somewhat less successful than expected and needs to be further investigated.

Conclusion:

The combination of PDT with immunotherapy by using multifunctional nanoparticles continues to develop and seems to be the most promising for achieving a complete and lasting antitumour effect.

Spatial and temporal patterns in dynamic-contrast enhanced intraoperative fluorescence imaging enable classification of bone perfusion in patients undergoing leg amputation

Dynamic contrast-enhanced fluorescence imaging (DCE-FI) classification of tissue viability in twelve adult patients undergoing below knee leg amputation is presented. During amputation and with the distal bone exposed, indocyanine green contrast-enhanced images were acquired sequentially during baseline, following transverse osteotomy and following periosteal stripping, offering a uniquely well-controlled fluorescence dataset. An unsupervised classification machine leveraging 21 different spatiotemporal features was trained and evaluated by cross-validation in 3.5 million regions-of-interest obtained from 9 patients, demonstrating accurate stratification into normal, suspicious, and compromised regions. The machine learning (ML) approach also outperformed the standard method of using fluorescence intensity only to evaluate tissue perfusion by a two-fold increase in accuracy. The generalizability of the machine was evaluated in image series acquired in an additional three patients, confirming the stability of the model and ability to sort future patient image-sets into viability categories.

Photothermal and Photodynamic Therapy of Tumors with Plasmonic Nanoparticles: Challenges and Prospects

Cancer remains one of the leading causes of death in the world. For a number of neoplasms, the efficiency of conventional chemo- and radiation therapies is insufficient because of drug resistance and marked toxicity. Plasmonic photothermal therapy (PPT) using local hyperthermia induced by gold nanoparticles (AuNPs) has recently been extensively explored in tumor treatment. However, despite attractive promises, the current PPT status is limited by laboratory experiments, academic papers, and only a few preclinical studies. Unfortunately, most nanoformulations still share a similar fate: great laboratory promises and fair preclinical trials. This review discusses the current challenges and prospects of plasmonic nanomedicine based on PPT and photodynamic therapy (PDT). We start with consideration of the fundamental principles underlying plasmonic properties of AuNPs to tune their plasmon resonance for the desired NIR-I, NIR-2, and SWIR optical windows. The basic principles for simulation of optical cross-sections and plasmonic heating under CW and pulsed irradiation are discussed. Then, we consider the state-of-the-art methods for wet chemical synthesis of the most popular PPPT AuNPs such as silica/gold nanoshells, Au nanostars, nanorods, and nanocages. The photothermal efficiencies of these nanoparticles are compared, and their applications to current nanomedicine are shortly discussed. In a separate section, we discuss the fabrication of gold and other nanoparticles by the pulsed laser ablation in liquid method. The second part of the review is devoted to our recent experimental results on laser-activated interaction of AuNPs with tumor and healthy tissues and current achievements of other research groups in this application area. The unresolved issues of PPT are the significant accumulation of AuNPs in the organs of the mononuclear phagocyte system, causing potential toxic effects of nanoparticles, and the possibility of tumor recurrence due to the presence of survived tumor cells. The prospective ways of solving these problems are discussed, including developing combined antitumor therapy based on combined PPT and PDT. In the conclusion section, we summarize the most urgent needs of current PPT-based nanomedicine.

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.

Assessment of tissue-specific changes in structure and function induced by in vivo skin/skull optical clearing techniques

BACKGROUND OBJECTIVES

Newly developed in vivo skin and skull optical clearing techniques can greatly improve the optical imaging performance, showing great advantages and clinical prospects. However, there is a poor understanding of in vivo optical clearing-induced changes in the skin and skull.

MATERIALS AND METHODS

Here, we employed in vivo skin/skull optical clearing techniques to improve the optical coherence tomography (OCT) imaging quality. And we also used polarization-sensitive OCT to monitor the dynamic changes in the polarization characteristics of the skin and skull during in vivo optical clearing processes. Two-photon imaging was used to evaluate changes in tissue barrier function and structure. Additionally, Raman spectra were employed for assessing the changes of each component in the skin and skull before and after optical clearing treatment.

RESULTS

The results indicated that the polarization states of the skin and skull were altered with the usages of optical clearing agents. And the barrier permeability and collagen fiber distribution of them became disordered. Furthermore, the Raman spectra of tissue demonstrated that the applications of in vivo tissue optical clearing methods could lead to the reduction of proteins, lipids, and inorganic salts in these two organs. Interestingly, after recovery treatment, the structure and function of the skin and skull could almost recover to the initial states.

CONCLUSION

In vivo tissue optical clearing can lead to changes in the structure and function of tissue, which was reversible to some extent. This study plays an important role in revealing the underlying mechanisms of tissue optical clearing techniques; moreover, it is conducive to the development and optimization of a novel in vivo tissue optical clearing approaches in future.

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.

Volumetric tumor delineation and assessment of its early response to radiotherapy with optical coherence tomography

Texture analyses of optical coherence tomography (OCT) images have shown initial promise for differentiation of normal and tumor tissues. This work develops a fully automatic volumetric tumor delineation technique employing quantitative OCT image speckle analysis based on Gamma distribution fits. We test its performance in-vivo using immunodeficient mice with dorsal skin window chambers and subcutaneously grown tumor models. Tumor boundaries detection is confirmed using epi-fluorescence microscopy, combined photoacoustic-ultrasound imaging, and histology. Pilot animal study of tumor response to radiotherapy demonstrates high accuracy, objective nature, novelty of the proposed method in the volumetric separation of tumor and normal tissues, and the sensitivity of the fitting parameters to radiation-induced tissue changes. Overall, the developed methodology enables hitherto impossible longitudinal studies for detecting subtle tissue alterations stemming from therapeutic insult.

Photoimmunotherapy Using Cationic and Anionic Photosensitizer-Antibody Conjugates against HIV Env-Expressing Cells

Different therapeutic strategies have been investigated to target and eliminate HIV-1-infected cells by using armed antibodies specific to viral proteins, with varying degrees of success. Herein, we propose a new strategy by combining photodynamic therapy (PDT) with HIV Env-targeted immunotherapy, and refer to it as HIV photoimmunotherapy (PIT). A human anti-gp41 antibody (7B2) was conjugated to two photosensitizers (PSs) with different charges through different linking strategies; "Click" conjugation by using an azide-bearing porphyrin attached via a disulfide bridge linker with a drug-to-antibody ratio (DAR) of exactly 4, and "Lysine" conjugation by using phthalocyanine IRDye 700DX dye with average DARs of 2.1, 3.0 and 4.4. These photo-immunoconjugates (PICs) were compared via biochemical and immunological characterizations regarding the dosimetry, solubility, and cell targeting. Photo-induced cytotoxicity of the PICs were compared using assays for apoptosis, reactive oxygen species (ROS), photo-cytotoxicity, and confocal microscopy. Targeted phototoxicity seems to be primarily dependent on the binding of PS-antibody to the HIV antigen on the cell membrane, whilst being independent of the PS type. This is the first report of the application of PIT for HIV immunotherapy by killing HIV Env-expressing cells.

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

Melanoma is the most aggressive type of skin cancer and a relevant health problem due to its poor treatment response with high morbidity and mortality rates. This study, aimed to investigate the tissue changes of an improved photodynamic therapy (PDT) response when combined with optical clearing agent (OCA) in the treatment of cutaneous melanoma in mice. Photodithazine (PDZ) was administered intraperitoneally and a solution of OCA was topically applied before PDT irradiation. Due to a resultant refractive index matching, OCA-treated tumors are more optically homogenous, improving the PDT response. Raman analysis revealed, when combined with OCA, the PDT response was more homogenous down to 725 µm-depth in thickness.