Immunomodulatory Effects by Photodynamic Treatment of Glioblastoma Cells In Vitro

Abstract

Multimodal treatment adding immunotherapy and photodynamic treatment (PDT) to standard therapy might improve the devastating therapeutic outcome of glioblastoma multiforme patients. As a first step, we provide investigations to optimize dendritic cell (DC) vaccination by using PDT and ionizing radiation (IR) to achieve maximal synergistic effects. In vitro experiments were conducted on murine glioblastoma GL261 cells, primary DCs differentiated from bone marrow and T cells, isolated from the spleen. Induction of cell death, reactive oxygen species, and inhibition of proliferation by tetrahydroporphyrin-tetratosylat (THPTS)-PDT and IR were confirmed by WST-1, LDH, ROS, and BrdU assay. Tumor cargo (lysate or cells) for DC load was treated with different combinations of THPTS-PDT, freeze/thaw cycles, and IR and immunogenicity analyzed by induction of T-cell activation. Cellular markers (CD11c, 83, 86, 40, 44, 69, 3, 4, 8, PD-L1) were quantified by flow cytometry. Cytotoxic T-cell response was evaluated by calcein AM assay. Immunogenicity of THPTS-PDT-treated GL261 cells lysate was superior to IR-treated lysate, or treated whole cells proven by increased DC phagocytosis, T-cell adhesion, proliferation, cytolytic activity, and cytokine release. These data strongly support the application of PDT together with IR for optimal immunogenic cell death induction in tumor cell lysate used to pulse DC vaccines.

Two Molecular Weights Holothurian Glycosaminoglycan and Hematoporphyrin Derivative-Photodynamic Therapy Inhibit Proliferation and Promote Apoptosis of Human Lung Adenocarcinoma Cells

“…The antitumor mechanisms of PDT include inducing tumor cell necrosis, apoptosis and autophagy, regulating immune response, and destroying tumor nutrient vessels. [34][35][36][37][38][39] Because of the capability of normal tissues to clear or eliminate the photosensitizers, the photochemical reaction almost occurs in pathological tissues, and there are almost no phototoxic effects in surrounding normal tissues. 37 Compared with conventional treatments, PDT has the advantages of less trauma, less toxicity, repeatability, and high selectivity.…”

Molecular Insights into Photodynamic Therapy of Glioma

“…The presence of PD-1 may adversely affect the efficacy of dendritic cells, which dysfunctionally limit antigen-specific T-cell responses in glioma [217,218]. Several works have shown that PDT of glioma with different PS can improve DC functionality [219][220][221][222]. Since anti-PD-1 treatment during DC maturation resulted in increased DC survival, the approach of combining PDT and a method that blocks the PD-1/PD-L1 axis could therefore be an attractive improvement on the hitherto suboptimal results of glioma dendritic cell therapy [217,223].…”

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

“…Additionally, the 5-ALA compound is a precursor to the potent photosensitizer, protoporphyrin IX ( PpIX ). When PpIX is excited by 635 nm light, it generates triplet oxygen species triggering cytotoxicity as a photosensitizer [ 11 , 12 , 13 , 14 , 15 , 16 ]. Therefore, if we use both the fluorophore and photosensitizer (PS) capabilities of protoporphyrin IX ( PpIX ) at the same time, we will be able to visually identify neoplastic tissue and, at the same time, we can selectively destroy that tissue, thus improving the GB treatment success.…”