No abstract

The lack of experimentally tractable models that recapitulate brain structure and function represents a major impediment in the development of novel treatment options for brain cancer. In vitro assays, though fast and high throughput, produce artificial results which do not fully encompass the clinically relevant outcome. Low passage patient derived cell lines offer an advantage over immortalized cell lines in terms of relation to the clinical presentation. Low passage patient derived cell lines, however, show slower growth and decreased tumorgenicity. We have previously shown that the use of organotypic brain slice culture (OBSCs) can recapitulate growth patterns and migration which is seen in vivo. We have further expanded the OBSCs to study their use as a model for patient derived cell lines. Some cell lines such as MS21, a human glioblastoma, or IFF109-DMG, a human pediatric diffuse midline glioma, are simply supported over a four-day time period, whereas other lines such as IFF105-DIPG, a pediatric human diffuse intrinsic pontine glioma, can grow over 3-fold in a 4-day time period. Additionally, we can assess treatment response to a variety of clinically relevant chemotherapeutics. The decreased variability with the OBSCs allows for the assessment of minute differences in treatment response. Overall, these results suggest the OBSC with patient derived cell lines have the potential to be effective models to accelerate preclinical evaluation of therapeutics and guide drug development towards more effective treatment strategies.

Brain cancers remain one of the greatest medical challenges. The lack of experimentally tractable models that recapitulate brain structure/function represents a major impediment. Platforms that enable functional testing in high-fidelity models are urgently needed to accelerate the identification and translation of therapies to improve outcomes for patients suffering from brain cancer. In vitro assays are often too simple and artificial while in vivo studies can be time-intensive and complicated. Our live, organotypic brain slice platform can be used to seed and grow brain cancer cell lines, allowing us to bridge the existing gap in models. These tumors can rapidly establish within the brain slice microenvironment, and morphologic features of the tumor can be seen within a short period of time. The growth, migration, and treatment dynamics of tumors seen on the slices recapitulate what is observed in vivo yet is missed by in vitro models. Additionally, the brain slice platform allows for the dual seeding of different cell lines to simulate characteristics of heterogeneous tumors. Furthermore, live brain slices with embedded tumor can be generated from tumor-bearing mice. This method allows us to quantify tumor burden more effectively and allows for treatment and retreatment of the slices to understand treatment response and resistance that may occur in vivo. This brain slice platform lays the groundwork for a new clinically relevant preclinical model which provides physiologically relevant answers in a short amount of time leading to an acceleration of therapeutic translation.

High-grade pediatric brain tumors (PBTs) such as diffuse intrinsic pontine glioma (DIPG) and diffuse midline glioma (DMG) are devastating diseases with a median survival of just 11 months. Little progress has been made in identifying effective treatments due to the lack of effective pre-clinical models to accurately assess drug sensitivity. Historically, models of DIPG and DMG have been limited due to the low availability of surgical biopsies and small patient populations. Existing in vitro models are often unable to recapitulate growth and migration patterns seen in patients, while in vivo work is costly, time intensive, and many biopsies fail to establish in mice. We have developed an ex vivo organotypic brain slice culture (OBSC) platform to model DIPG and DMG. Through our partnership with the Ian’s Friends Foundation and Children’s Healthcare of Atlanta Biobank, we have seeded, grown, and treated several low-passage patient-derived PBT lines such as DIPG and DMG. Additionally, we can assess treatment response to a variety of agents used in clinical patient care. Viability assays revealed differences in the sensitivity of cell lines to individual agents, indicating that OBSCs have the potential to capture minute differences in efficacy between cell lines and drugs. When we assessed combination treatments, we found low doses of radiation with low doses of temozolomide were synergistic, but using higher doses of radiation was antagonistic, suggesting the OBSC platform has the potential to guide dosing strategies to maximize therapeutic synergy. Overall, these results suggest that OBSC PBT models have the potential to effectively model PBTs, including DIPG and DMG, to accelerate preclinical evaluation of therapeutics and guide drug development towards more effective treatment strategies.