Real-time imaging of glioblastoma using bioluminescence in a U-87 MG xenograft model mouse

Temozolomide-loaded bacterial magnetosomes improve targeted therapy for brain tumors

Novel active-targeting nano-therapeutic, Temozolomide-loaded magnetosomes conjugate has been developed to address the challenges of high metastatic rates and recurrence of tumors due to tumor circulating cells. Temozolomide-loaded magnetosomes as drug conjugate were characterized through a scanning electron microscope, Zeta-sizer, and UV-visible spectroscopy. The anti-tumor activity was studied in vitro (Cell viability, Cell proliferation, and flow cytometry) and in vivo (Xenograft tumor model). The particle size of temozolomide-coated magnetosomes is larger than that of uncoated magnetosomes. The zeta potential decreased to -11.2 from -21.6 mV for Temozolomide- magnetosomes conjugates. The drug-coated magnetosomes can sustain drug release, reducing the frequency of administration and enhancing their therapeutic effect. The study found that Temozolomide-loaded magnetosomes conjugate showed enhanced tumor cytotoxicity and apoptosis than free Temozolomide or magnetosomes. In vivo, the treatment of mice with Temozolomide-loaded magnetosomes inhibited tumor growth to 405.25 mm3 and reduced tumor weight (0.60 g), with fewer juvenile cells and increased necrotic area. These results suggest Bacterial magnetosomes as an appropriate choice for cancer therapy since they may be superior drug carriers with increased therapeutic efficacy and no undesirable side effects to the brain.

Highly Invasive Fluorescent/Bioluminescent Patient-Derived Orthotopic Model of Glioblastoma in Mice

Development of the novel diagnostic and therapeutic approaches in neuro-oncology requires tumor models that closely reproduce the biological features of patients' tumors. Patient-derived xenografts (PDXs) are recognized as a valuable and the most "close-to-patient" tool for preclinical studies. However, their establishment is complicated by the factors related to both the surgical material and technique of the orthotopic implantation. The aim of this work was to develop a patient-derived glioblastoma multiform (GBM) model that stably co-expresses luciferase and a far-red fluorescent protein for monitoring of tumor progression in the brain and, using this model, to validate new diagnostic methods-macroscopic fluorescence lifetime imaging (macro-FLIM) and cross-polarization optical coherence tomography (CP OCT). The established model was similar to the original patient's GBM in terms of histological and immunohistochemical features and possessed reproducible growth in nude mice, which could be observed by both fluorescence and bioluminescence imaging. Our results demonstrated the high potential of macro-FLIM and CP OCT for intraoperative differentiation of GBM from the white matter. Thus, the dual-labeled PDX model of GBM proved to be an excellent approach for observation of tumor development by optical methods.

The expression of B7-H3 isoforms in newly diagnosed glioblastoma and recurrence and their functional role

Short survival of glioblastoma (GBM) patients is due to systematic tumor recurrence. Our laboratory identified a GBM cell subpopulation able to leave the tumor mass (TM) and invade the subventricular zone (SVZ-GBM cells). SVZ-GBM cells escape treatment and appear to contribute to GBM recurrence. This study aims to identify proteins specifically expressed by SVZ-GBM cells and to define their role(s) in GBM aggressiveness and recurrence. The proteome was compared between GBM cells located in the initial TM and SVZ-GBM cells using mass spectrometry. Among differentially expressed proteins, we confirmed B7-H3 by western blot (WB) and quantitative RT-PCR. B7-H3 expression was compared by immunohistochemistry and WB (including expression of its isoforms) between human GBM (N = 14) and non-cancerous brain tissue (N = 8), as well as newly diagnosed GBM and patient-matched recurrences (N = 11). Finally, the expression of B7-H3 was modulated with short hairpin RNA and/or over-expression vectors to determine its functional role in GBM using in vitro assays and a xenograft mouse model of GBM. B7-H3 was a marker for SVZ-GBM cells. It was also increased in human GBM pericytes, myeloid cells and neoplastic cells. B7-H3 inhibition in GBM cells reduced their tumorigenicity. Out of the two B7-H3 isoforms, only 2IgB7-H3 was detected in non-cancerous brain tissue, whereas 4IgB7-H3 was specific for GBM. 2IgB7-H3 expression was higher in GBM recurrences and increased resistance to temozolomide-mediated apoptosis. To conclude, 4IgB7-H3 is an interesting candidate for GBM targeted therapies, while 2IgB7-H3 could be involved in recurrence through resistance to chemotherapy.

The splicing FK506-binding protein-51 isoform plays a role in glioblastoma resistance through programmed cell death ligand-1 expression regulation

Gliomas aberrantly express programmed cell death ligand-1 (PD-L1), which has a pivotal role in immunoevasion. The splicing isoform of FKBP5, termed FKBP51s, is a PD-L1 foldase, assisting the immune checkpoint molecule in maturation and expression on the plasma membrane. The concept that PD-L1 supports tumor-intrinsic properties is increasingly emerging. The aim of the present work was to confirm the pro-tumoral effect of PD-L1 on human glioma cell survival, stemness capacity and resistance, and to address the issue of whether, by targeting its foldase either chemically or by silencing, the aggressive tumor features could be attenuated. PD-L1-depleted glioma cells have a reduced threshold for apoptosis, while PD-L1 forced expression increases resistance. Similar results were obtained with FKBP51s modulation. The ability of PD-L1 to counteract cell death was hampered by FKBP51s silencing. PD-L1 expression was particularly high in glioma cells with a cancer-stem-cell profile. Moreover, PD-L1 sustained the spheroid formation capability of glioma cells. Targeting of FKBP51s by small-interfering RNA (siRNA) or the specific inhibitor SAFit2, reduced the number of formed spheroids, along with PD-L1 expression. Finally, in an orthotopic mouse model of glioblastoma, daily treatment with SAFit2 significantly reduced tumor PD-L1 expression, and tumor growth. In treated mice, caspase-3 activation and reduced vimentin expression were observed in excised tumors. In conclusion, targeting of FKBP51s hampers PD-L1 and its pro-tumoral properties, thereby affecting the self-renewal and growth capacities of glioblastoma cells in vitro and in vivo.

Dual-selective photodynamic therapy with a mitochondria-targeted photosensitizer and fiber optic cannula for malignant brain tumors

Among brain tumors, glioblastoma multiforme (GBM) is the most common and aggressive form (WHO grade IV) with a median survival of only 14.6 months in adults. Photodynamic therapy (PDT) is a combination of a photosensitizer (PS), light and molecular oxygen, and considered a promising treatment for GBM. Therapeutic outcomes of PDT rely on ROS generation in a tumor microenvironment, which can be controlled with dual selectivity by localization of the photosensitizer and confinement of light to the targeted tumor microenvironment. We previously demonstrated the photodynamic anticancer efficacy of mitochondrial-targeted photosensitizer-loaded albumin nanoparticles (PS@chol-BSA NPs). In this study, the photodynamic therapeutic effect of PS@chol-BSA NPs was further enhanced by confinement of light using a fiber optic cannula in orthotopic GBM-xenografted mice. In vitro cellular uptake and phototoxicity of PS@chol-BSA NPs were evaluated in brain tumor (U87MG) and endothelial (bEnd.3) cells. In vivo biodistribution was determined by an in vivo imaging system (IVIS) and the photodynamic efficacy was evaluated with confined laser irradiation. PS@chol-BSA NPs showed higher cellular uptake and phototoxicity in U87MG cells than in bEnd.3 cells. PS@chol-BSA NPs showed a brain tumor accumulation of 0.2%ID within 2 h and remain in the brain tumor for 22 h. When compared to the control group, there was remarkable suppression in tumor growth by laser irradiation with and without the fiber optic cannula at a dose of 1 mg kg^-1, in which significant tumor suppression up to 40% was observed with confined laser irradiation. Together, dual-selective photodynamic therapy with a mitochondria-targeted photosensitizer and fiber optic cannula provides a promising therapeutic strategy for malignant brain tumors.

Investigation on the effect of nanoparticle size on the blood-brain tumour barrier permeability by in situ perfusion via internal carotid artery in mice

The blood-brain barrier (BBB) is a limiting factor in nanoparticle drug delivery to the brain, and various attempts have been made to overcome it for efficient drug delivery. Nowadays, it was considered as further issue for brain-drug delivery that the nanoparticle delivered to brain through the BBB reach cancer cells in tumour tissue. In this study, we investigated the effect of nanoparticle size on blood-brain tumour barrier (BBTB) permeation of fluorescence-labelled gold nanoparticles (AuNPs) in a mouse model of orthotopic glioblastoma multiforme (GBM), established by intracranial implantation of luciferase-expressing human glioblastoma U87MG cells. AuNPs sized 10, 50, and 100 nm were perfused into the GBM mice via internal carotid artery (ICA) for 5 min. Immediately after perfusion, the brains were fixed and prepared for LSCM observation. The AuNPs distribution in the normal and tumorous brain tissues was analysed qualitatively and quantitatively. Higher distribution of AuNPs was observed in the tumorous tissue than in the normal tissue. Furthermore, the smallest nanoparticle, 10 nm AuNPs, was widely distributed in the brain tumour tissue, whereas the 50 and 100 nm AuNPs were located near the blood vessels. Therefore, nanoparticle size affected the permeation of nanoparticles from the blood into brain tumour tissue.