In vivo imaging of encapsulated stem cells in mouse models of tumor resection

描述（由申请人提供）：多形性恶性胶质母细胞瘤（GBM）的标准治疗包括最大手术切除肿瘤，然后放射治疗和辅助化疗。然而，GBM的复发率和相关的患者死亡率接近100%。尽管肿瘤切除在临床GBM治疗中起着关键作用，但大多数临床前研究都集中在治疗实体完整的颅内GBM肿瘤上，而没有模拟手术切除的临床场景。因此，在重现临床疾病特征的小鼠模型中实施肿瘤切除对于开发可用于GBM的临床可翻译疗法至关重要。在拟议的研究中，我们将首先使用基于3种不同表型（侵袭性、半侵袭性和结节性）的患者源性CD133+ GBM创建并表征不同的GBM切除模型。虽然原发肿瘤切除已显示出临床益处，但系统输送化疗药物或直接注射病毒和

DESCRIPTION (provided by applicant): The standard treatment for malignant glioblastoma multiforme (GBM) includes maximal surgical tumor resection followed by radiation therapy and adjuvant chemotherapy. However, recurrence rates of GBM and the associated patient mortality are nearly 100%. Despite the key role of tumor resection in clinical GBM therapy, most of the pre-clinical studies focus on treating solid intact intracranial GBM tumors without mimicking the clinical scenario of surgical resection. Therefore, implementation of tumor resection in mouse models that recapitulate the clinical disease features are critical in developing clinically translatable therapies for GBM. In the proposed studies, we will first create and characterize different GBM resection models using patient derived CD133+ GBMs based on 3 different phenotypes (invasive, semi-invasive and nodular). While resection of primary tumor has shown clinical benefit, systemically delivered chemotherapeutic agents or direct injection of viruses and placement of carmustine (BCNU) wafers in tumor resection cavities has provided very limited additional benefit. Based on our recent findings that encapsulation of mesenchymal stem cells (MSC) is necessary to prevent rapid "wash- out" of stem cells post-transplantation in the tumor resection cavity, we will encapsulate human MSC engineered to express in vitro and in vivo imaging markers into synthetic extracellular matrices (sECMs) and evaluate them for their retention, survival and tumor homing in mouse resection models of GBM with different phenotypes. Based on our preliminary studies which indicate that a novel anti-tumor agent consisting of a secretable version of epidermal growth factor receptor targeted nanobody fused to tumor necrosis factor apoptosis inducing ligand (Enb-TRAIL), induces GBM cell killing in both TRAIL resistant and sensitive GBMs, encapsulated MSC-Enb- TRAIL will be tested in different GBM models of resection. To ensure the safety of our approach, we will ultimately engineer human MSC-Enb-TRAIL to express HSV-thymidine kinase (TK), an activatable cellular suicide gene that will allow us to selectively eradicate MSC post-GBM treatment. The incorporation of genetically engineered fluorescent and bioluminescent imaging (BLI) markers into MSC and GBMs will allow us to follow GBM cell invasion, fate of MSC and pharmacokinetics of therapeutic proteins and their efficacy by in vivo BLI, intravital microscopy (IVM), magnetic resonance imaging (MRI) and positron emission tomography (PET) and thus to fine tune the proposed approaches. Once validated, we will initiate a clinical study in which at the time of brain tumor surgery, the main tumor mass will be removed and sECMs encapsulated MSC will be introduced to target a broad spectrum of remaining tumor cells and micro-invasive tumor deposits in the brain. This will have a major impact in saving the lives of many brain cancer patients.