An In Vitro Approach to Photodynamic Therapy

The use of photodynamic therapy in medical practice

Cancer therapy, especially for tumors near sensitive areas, demands precise treatment. This review explores photodynamic therapy (PDT), a method leveraging photosensitizers (PS), specific wavelength light, and oxygen to target cancer effectively. Recent advancements affirm PDT's efficacy, utilizing ROS generation to induce cancer cell death. With a history spanning over decades, PDT's dynamic evolution has expanded its application across dermatology, oncology, and dentistry. This review aims to dissect PDT's principles, from its inception to contemporary medical applications, highlighting its role in modern cancer treatment strategies.

Blue light aminolevulinic acid photodynamic therapy downregulates cell division and proliferation pathways in cutaneous squamous cell carcinoma

5-Aminolevulinic acid (5-ALA) photodynamic therapy (PDT) is a treatment for actinic keratosis (AK) and has been studied as a treatment for noninvasive cutaneous squamous cell carcinoma (cSCC). PDT induces apoptosis and necrosis in AKs and cSCC. 5-ALA blue light PDT may modulate gene expression and pathways in surviving cells. In this study, differential gene expression and pathway analysis of cSCC and human dermal fibroblasts were compared before and after 5-ALA blue light PDT using RNA sequencing. No genes were differentially expressed after correcting for multiple testing (false discovery rate < 0.05). As a result, transcription factor, gene enrichment, and pathway analysis were performed with genes identified before multiple testing (p < 0.05). Pathways associated with proliferation and carcinogenesis were downregulated. These findings using 5-ALA blue light PDT are similar to previously published studies using methyl-aminolevulinic and red light protocols, indicating that surviving residual cells may undergo changes consistent with a less aggressive cancerous phenotype.

CD271 activation prevents low to high-risk progression of cutaneous squamous cell carcinoma and improves therapy outcomes

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) is the second most prevalent form of skin cancer, showing a rapid increasing incidence worldwide. Although most cSCC can be cured by surgery, a sizeable number of cases are diagnosed at advanced stages, with local invasion and distant metastatic lesions. In the skin, neurotrophins (NTs) and their receptors (CD271 and Trk) form a complex network regulating epidermal homeostasis. Recently, several works suggested a significant implication of NT receptors in cancer. However, CD271 functions in epithelial tumors are controversial and its precise role in cSCC is still to be defined.

METHODS

Spheroids from cSCC patients with low-risk (In situ or Well-Differentiated cSCC) or high-risk tumors (Moderately/Poorly Differentiated cSCC), were established to explore histological features, proliferation, invasion abilities, and molecular pathways modulated in response to CD271 overexpression or activation in vitro. The effect of CD271 activities on the response to therapeutics was also investigated. The impact on the metastatic process and inflammation was explored in vivo and in vitro, by using zebrafish xenograft and 2D/3D models.

RESULTS

Our data proved that CD271 is upregulated in Well-Differentiated tumors as compared to the more aggressive Moderately/Poorly Differentiated cSCC, both in vivo and in vitro. We demonstrated that CD271 activities reduce proliferation and malignancy marker expression in patient-derived cSCC spheroids at each tumor grade, by increasing neoplastic cell differentiation. CD271 overexpression significantly increases cSCC spheroid mass density, while it reduces their weight and diameter, and promotes a major fold-enrichment in differentiation and keratinization genes. Moreover, both CD271 overexpression and activation decrease cSCC cell invasiveness in vitro. A significant inhibition of the metastatic process by CD271 was observed in a newly established zebrafish cSCC model. We found that the recruitment of leucocytes by CD271-overexpressing cells directly correlates with tumor killing and this finding was further highlighted by monocyte infiltration in a THP-1-SCC13 3D model. Finally, CD271 activity synergizes with Trk receptor inhibition, by reducing spheroid viability, and significantly improves the outcome of photodynamic therapy (PTD) or chemotherapy in spheroids and zebrafish.

CONCLUSION

Our study provides evidence that CD271 could prevent the switch between low to high-risk cSCC tumors. Because CD271 contributes to maintaining active differentiative paths and favors the response to therapies, it might be a promising target for future pharmaceutical development.

A Warp-Knitted Light-Emitting Fabric-Based Device for In Vitro Photodynamic Therapy: Description, Characterization, and Application on Human Cancer Cell Lines

Simple Summary

While photodynamic therapy appears to be a promising approach to treating cancers, the complexity of its parameters prevents wide acceptance. Accurate light dose measurement is one of the keys to photodynamic effect assessment, but it remains challenging when comparing different technologies. This work provides a complete demonstration of the technical performance of a homemade optical device, based on knitted light-emitting fabrics, called CELL-LEF. Thermal and optical distributions and related safeties are investigated. The results are discussed in relation to the requirements of photodynamic therapy. The usability of CELL-LEF is investigated on human cancer cell lines as a proof of concept. This study highlights that new light-emitting fabric-based technologies can be relevant light sources for in vitro photodynamic therapy studies of tomorrow.

Abstract

Photodynamic therapy (PDT) appears to be a promising strategy in biomedical applications. However, the complexity of its parameters prevents wide acceptance. This work presents and characterizes a novel optical device based on knitted light-emitting fabrics and dedicated to in vitro PDT involving low irradiance over a long illumination period. Technical characterization of this device, called CELL-LEF, is performed. A cytotoxic study of 5-ALA-mediated PDT on human cancer cell lines is provided as a proof of concept. The target of delivering an irradiance of 1 mW/cm² over 750 cm² is achieved (mean: 0.99 mW/cm²; standard deviation: 0.13 mW/cm²). The device can maintain a stable temperature with the mean thermal distribution of 35.1 °C (min: 30.7 °C; max: 38.4 °C). In vitro outcomes show that 5-ALA PDT using CELL-LEF consistently and effectively induced a decrease in tumor cell viability: Almost all the HepG2 cells died after 80 min of illumination, while less than 60% of U87 cell viability remained. CELL-LEF is suitable for in vitro PDT involving low irradiance over a long illumination period.

Investigation of the therapeutic effect of 5-aminolevulinic acid based photodynamic therapy on hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a heterogeneous type of cancer and current treatment options limit successful therapy outcomes. Photodynamic therapy (PDT) has attracted attention as an alternative approach in the treatment of different types of cancer. However, there is no study in the literature regarding the effect of PDT on HCC, in vitro. Therefore, the aim of this study was to determine the cytotoxic and apoptotic effects of 5-aminolevulinic acid (5-ALA)/PDT on two different HCC cell lines in terms of hepatitis B virus (HBV) infection. The therapeutic effects of 5-ALA-based PDT on HCC cell lines (Huh-7 and SNU-449) were evaluated by PpIX-fluorescence accumulation, WST-1 analysis, Annexin V analysis, and acridine orange/ethidium bromide staining after irradiation with different light doses through diode laser. The results showed that 1 mM 5-ALA displayed higher PpIX fluorescence in the SNU-449 cell line than the Huh-7 cell line after 4 h of incubation. After irradiation with different light doses (3, 6, 9, and 12 J/cm²), 5-ALA significantly reduced the proliferation of HCC cells and induced apoptotic cell death (p < 0.01). Furthermore, SNU-449 cells were more responsive to 5-ALA-based PDT than Huh-7 cells due to possibly its molecular features as well as viral HBV status. Our preliminary data obtained from this study may contribute to the development of 5-ALA/PDT-based treatment strategies in the treatment of HCC. However, this study could be improved by the elucidation of the molecular mechanisms of cell death induced by 5-ALA/PDT in HCC cells, the use of different photosensitizer, light sources, and in vivo experiments.

Evaluation of the effect of 5-aminolevulinic acid hexyl ester (H-ALA) PDT on EBV LMP1 protein expression in human nasopharyngeal cells

Nasopharyngeal carcinoma (NPC) is of high prevalence in Hong Kong and southern China. The pathogenesis of NPC is closely associated with Epstein-Barr virus (EBV) infection via regulation of viral oncoprotein latent membrane protein 1 (LMP1). The conventional treatment for NPC is chemo-radiotherapy, but the prognosis remains poor for advanced stage, recurrent and metastatic NPC. Photodynamic therapy (PDT) is a therapeutic approach to combat tumors. PDT effectiveness depends on the interaction of photosensitizers, light and molecular oxygen. 5- aminolevulinic acid hexyl derivative (H-ALA) is one of the photosensitizers derived from 5-ALA. H-ALA with improved lipophilic properties by adding a long lipophilic chain (hexyl group) to 5-ALA, resulted in better penetration into cell cytoplasm. In this study, the effect of H-ALA-PDT on NPC cells (EBV positive C666-1 and EBV negative CNE2) was investigated. The H-ALA mediated cellular uptake and cytotoxicity was revealed via flow cytometry analysis and MTT assay respectively. H-ALA PDT mediated protein modulation was analysed by western blot analysis. Our finding reported that the cellular uptake of H-ALA in C666-1 and CNE2 cells was in a time dependent manner. H-ALA PDT was effective to C666-1 and CNE2 cells. EBV LMP1 proteins was expressed in C666-1 cells only and its expression was responsive to H-ALA PDT in a dose dependent manner. This work revealed the potential of H-ALA PDT as a treatment regiment for EBV positive NPC cells. Understanding the mechanism of H-ALA mediated PDT could develop improved strategies for the treatment of NPC.

Photodynamic Therapy Using a New Folate Receptor-Targeted Photosensitizer on Peritoneal Ovarian Cancer Cells Induces the Release of Extracellular Vesicles with Immunoactivating Properties

Often discovered at an advanced stage, ovarian cancer progresses to peritoneal carcinoma, which corresponds to the invasion of the serosa by multiple tumor implants. The current treatment is based on the combination of chemotherapy and tumor cytoreduction surgery. Despite the progress and standardization of surgical techniques combined with effective chemotherapy, post-treatment recurrences affect more than 60% of women in remission. Photodynamic therapy (PDT) has been particularly indicated for the treatment of superficial lesions on large surfaces and appears to be a relevant candidate for the treatment of microscopic intraperitoneal lesions and non-visible lesions. However, the impact of this therapy on immune cells remains unclear. Hence, the objective of this study is to validate the efficacy of a new photosensitizer [pyropheophorbide a-polyethylene glycol-folic acid (PS)] on human ovarian cancer cells and to assess the impact of the secretome of PDT-treated cells on human peripheral blood mononuclear cells (PBMC). We show that PS, upon illumination, can induce cell death of different ovarian tumor cells. Furthermore, PDT using this new PS seems to favor activation of the immune response by inducing the secretion of effective cytokines and inhibiting the pro-inflammatory and immunosuppressive ones, as well as releasing extracellular vesicles (EVs) prone to activating immune cells. Finally, we show that PDT can activate CD4+ and CD8+ T cells, resulting in a potential immunostimulating process. The results of this pilot study therefore indicate that PS-PDT treatment may not only be effective in rapidly and directly destroying target tumor cells but also promote the activation of an effective immune response; notably, by EVs. These data thus open up good prospects for the treatment of micrometastases of intraperitoneal ovarian carcinosis which are currently inoperable.