Toxicological Assessment of 2-Hydroxychalcone-Mediated Photodynamic Therapy: Comparative In Vitro and In Vivo
Níura Madalena Bila1,2, Carolina Orlando Vaso1, Jenyffie Araújo Belizário1
1Department of Clinical Analysis, School of Pharmaceutical Sciences, Universidade Estadual Paulista (UNESP), Araraquara 14800-903, SP, Brazil.
Background:
Photodynamic therapy (PDT) is a treatment modality that uses light to activate a photosensitizing agent, destroying target cells. The growing awareness of the necessity to reduce or eliminate the use of mammals in research has prompted the search for safer toxicity testing models aligned with the new global guidelines and compliant with the relevant regulations.
Objective:
The objective of this study was to assess the impact of PDT on alternative models to mammals, including in vitro three-dimensional (3D) cultures and in vivo, in invertebrate animals, utilizing a potent photosensitizer, 2-hydroxychalcone.
Methods:
Cytotoxicity was assessed in two cellular models: monolayer (2D) and 3D. For this purpose, spheroids of two cell lines, primary dermal fibroblasts (HDFa) and adult human epidermal cell keratinocytes (HaCat), were developed and characterized following criteria on cell viability, shape, diameter, and number of cells. The survival percentages of Caenorhabditis elegans and Galleria mellonella were evaluated at 1 and 7 days, respectively.
Results:
The findings indicated that all the assessed platforms are appropriate for investigating PDT toxicity. Furthermore, 2-hydroxychalcone demonstrated low toxicity in the absence of light and when mediated by PDT across a range of in vitro (2D and 3D cultures) and in vivo (invertebrate animal models, including G. mellonella and C. elegans) models.
Conclusion:
There was a strong correlation between the in vitro and in vivo tests, with similar toxicity results, particularly in the 3D models and C. elegans, where the concentration for 50% viability was approximately 100 µg/mL.
Insights
Photodynamic therapy (PDT) shows low toxicity in alternative models. This study validates 3D cultures and invertebrate models for PDT toxicity testing, correlating well with in vitro and in vivo results.
Area of Science:
- Biomedical research
- Toxicology
- Photodynamic therapy
Background:
- Photodynamic therapy (PDT) uses light-activated photosensitizers to destroy target cells.
- Increasing demand for non-mammalian toxicity testing models aligns with global regulations.
- This study explores alternative models for PDT toxicity assessment.
Purpose of the Study:
- To evaluate the efficacy of photodynamic therapy (PDT) using 2-hydroxychalcone.
- To assess PDT's impact on alternative toxicity testing models, including 3D cultures and invertebrate animals.
- To validate these alternative models against established methods.
Main Methods:
- Cytotoxicity assays were performed on 2D monolayer and 3D spheroid cultures (fibroblasts and keratinocytes).
- In vivo toxicity was assessed in Caenorhabditis elegans and Galleria mellonella.
- Cell viability, morphology, and survival percentages were measured.
Main Results:
- All tested platforms (2D, 3D, C. elegans, G. mellonella) are suitable for PDT toxicity studies.
- 2-hydroxychalcone exhibited low toxicity in the absence of light and with PDT activation.
- Consistent toxicity profiles were observed across in vitro and in vivo models.
Conclusions:
- A strong correlation exists between in vitro and in vivo PDT toxicity testing results.
- Three-dimensional (3D) cell cultures and C. elegans showed particularly strong correlations.
- The findings support the use of these alternative models for reliable PDT toxicity evaluation.
