Multimodal Imaging of Photosensitizers in 3D tumor cell models

Introduction

Photodynamic therapy offers an innovative and alternative cancer treatment. A photosensitive compound (photosensitizer, PS) is administered and the tumor is subsequently irradiated. The activation of the PS leads to a formation of reactive oxygen species and subsequently to cell apoptosis. The compound 5,10,15,20-tetrakis(3- hydroxy-phenyl)-porphyrin (mTHPP), and its palladium-tagged analogue mTHPP-Pd were studied in this work (Figure 1). One main challenge in the development of PS is the hydrophobic character of the compounds that hinders the tissue penetration. Additionally, the orally administered compound needs to pass through the mucus layer in the gastro-intestinal tract. Thus, the determination of the penetration depth of those compounds is of great interest. The use of 3D tumor spheroids enables in vitro drug screening, while simulating the tumor environment better than 2D cell cultures. Here, the combination of elemental and molecular imaging by means of laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) and matrix-assisted laser desorption/ionization-mass spectrometry imaging (MALDI-MSI) was used to investigate the spatial distribution and concentration of mTHPP and mTHPP-Pd in 3D tumor spheroids.

October 27, 2020 GMT