• Modeling human pediatric and adult gliomas in immunocompetent mice through costimulatory blockade

      Lan, X.; Chu, C.; Jablonska, A.; Liang, Y.; Janowski, M.; Walczak, P. (Taylor and Francis Inc., 2020)
      Currently, human glioma tumors are mostly modeled in immunodeficient recipients; however, lack of interactions with adaptive immune system is a serious flaw, particularly in the era when immunotherapies dominate treatment strategies. Our group was the first to successfully establish the orthotopic transplantation of human glioblastoma (GBM) in immunocompetent mice by inducing immunological tolerance using a short-term, systemic costimulation blockade strategy (CTLA-4-Ig and MR1). In this study, we further validated the feasibility of this method by modeling pediatric diffuse intrinsic pontine glioma (DIPG) and two types of adult GBM (GBM1, GBM551), in mice with intact immune systems and immunodeficient mice. We found that all three glioma models were successfully established, with distinct difference in tumor growth patterns and morphologies, after orthotopic xenotransplantation in tolerance-induced immunocompetent mice. Long-lasting tolerance that is maintained for up to nearly 200 d in GBM551 confirmed the robustness of this model. Moreover, we found that tumors in immunocompetent mice displayed features more similar to the clinical pathophysiology found in glioma patients, characterized by inflammatory infiltration and strong neovascularization, as compared with tumors in immunodeficient mice. In summary, we have validated the robustness of the costimulatory blockade strategy for tumor modeling and successfully established three human glioma models including the pediatric DIPG whose preclinical study is particularly thwarted by the lack of proper animal models. Copyright 2020 the Author(s).
    • Optimization of osmotic blood-brain barrier opening to enable intravital microscopy studies on drug delivery in mouse cortex

      Jablonska, A.; Lan, X.; Janowski, M.; Walczak, P. (Elsevier B.V., 2020)
      Intra-arterial (IA) infusion of mannitol induces osmotic blood-brain barrier opening (OBBBO) and that method has been used for decades to improve drug delivery to the brain. However, high variability of outcomes prevented vast clinical adoption. Studies on dynamic multi-scale imaging of OBBBO as well as extravasation of IA injected therapeutic agents are essential to develop strategies assuring precision and reproducibility of drug delivery. Intravital microscopy is increasingly used to capture the dynamics of biological processes at the molecular level in convenient mouse models. However, until now OBBBO has been achieved safely in subcortical structures, which prevented direct insight into the process of extravasation through the skull window. Here, we used our previously developed real-time MRI to adjust the procedure to achieve robust cortical OBBBO. We found that catheter-mediated delivery to the cortex from the ipsilateral carotid artery can be improved by temporarily occluding the contralateral carotid artery. The reproducibility and safety of the method were validated by MRI and histology. This experimental platform was further exploited for studying with intravital microscopy the extravasation of 0.58 kDa rhodamine and 153 kDa anti-VEGF monoclonal antibody (bevacizumab) upon IA injection. Dynamic imaging during IA infusion captured the spatiotemporal dynamic of infiltration for each molecule into the brain parenchyma upon OBBBO. Small-sized rhodamine exhibited faster and higher penetration than the antibody. Histological analysis showed some uptake of the monoclonal antibody after IA delivery, and OBBBO significantly amplified the extent of its uptake. For quantitative assessment of cortical uptake, bevacizumab was radiolabeled with zirconium-89 and infused intraarterially. As expected, OBBBO potentiated brain accumulation, providing 33.90 ± 9.06% of injected dose per gram of brain tissue (%ID/g) in the cortex and 17.09 ± 7.22%ID/g in subcortical structures. In contrast IA infusion with an intact BBB resulted in 3.56 ± 1.06%ID/g and 3.57 ± 0.59%ID/g in the same brain regions, respectively. This study established reproducible cortical OBBBO in mice, which enabled multi-photon microscopy studies on OBBBO and drug targeting. This approach helped demonstrate in a dynamic fashion extravasation of fluorescently-tagged antibodies and their effective delivery into the brain across an osmotically opened BBB.