Preclinical Studies with Glioblastoma Brain Organoid Co-Cultures Show Efficient 5-ALA Photodynamic Therapy

[Background] The high recurrence of glioblastoma (GB) that occurs adjacent to the resection cavity within two years of diagnosis urges an improvement of therapies oriented to GB local control. Photodynamic therapy (PDT) has been proposed to cleanse infiltrating tumor cells from parenchyma to ameliorate short long-term progression-free survival. We examined 5-aminolevulinic acid (5-ALA)-mediated PDT effects as therapeutical treatment and determined optimal conditions for PDT efficacy without causing phototoxic injury to the normal brain tissue.

[Methods] We used a platform of Glioma Initiation Cells (GICs) infiltrating cerebral organoids with two different glioblastoma cells, GIC7 and PG88. We measured GICs-5-ALA uptake and PDT/5-ALA activity in dose-response curves and the efficacy of the treatment by measuring proliferative activity and apoptosis.

[Results] 5-ALA (50 and 100 µg/mL) was applied, and the release of protoporphyrin IX (PpIX) fluorescence measures demonstrated that the emission of PpIX increases progressively until its stabilization at 24 h. Moreover, decreased proliferation and increased apoptosis corroborated the effect of 5-ALA/PDT on cancer cells without altering normal cells.

[Conclusions] We provide evidence about the effectiveness of PDT to treat high proliferative GB cells in a complex in vitro system, which combines normal and cancer cells and is a useful tool to standardize new strategic therapies.

This research was funded Laboratorios Gebro Pharma S.A. The authors also received support from the Spanish Ministry of Health and Consumer Affairs, the ISCIII-Subdirección General de Evaluación, AECC (Spanish Association Against Cancer. Project GCTRA16015SEDA) and the Fondo Europeo de Desarrollo Regional (FEDER) FIS-PI18/00916. A.S. was supported by the grant PGC 2018-098626-B-100 funded by MCIN/AEI/10.13039/501100011033 and by the ERDF A way of making Europe, the grant PDC 2022-133826-100 funded by MCIN/AEI/10.13039/501100011033 and by the European Union Next GenerationEU/PRTR and the Merck Salud Foundation grant RL001213. A.S. is a recipient of a Ramón y Cajal contract supported by the Grant (RYC-2016-19962) funded by MCIN/AEI/10.13039/501100011033 and by the “ESF investing in your future”. C.B. is a recipient of Grant CEX2018-000794-S funded by MCIN/AEI/10.13039/501100011033.

With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2018-000794-S)

Peer reviewed