Glioblastoma (GBM) is the most common primary malignant brain tumor affecting adults, with a median survival time of 12-15 months. The standard of care for treating GBMs is maximum tumor resection followed by concomitant radiation and temozolomide therapy. However, tumor cells remain in the brain after resection, posing the threat of disease recurrence. Systemically administered treatments like radiation and chemotherapies are not targeted to the microscopic tumor lesions present in the brain post-surgery and are thus ineffective at preventing recurrence for 90% of GBM patients. Our group and others have demonstrated the promise of therapeutic neural stem cells (tNSCs) as a drug delivery platform for treating post-operative GBM due to an innate property known as tumor tropism. tNSCs interact with cytokines secreted by GBM cells, initiating a signaling cascade which results in tNSC migration in the direction of the tumor. This directional migration can be leveraged as a targeting mechanism for the delivery of drugs secreted by genetically engineered tNSCs. However, the platform's durability is limited by rapid clearance of tNSCs implanted directly into the GBM resection cavity. Encapsulation of tNSCs in biomaterials when delivered into the cavity could prevent this rapid clearance and lengthen the duration of therapeutic efficacy. Our group has demonstrated that biocompatible materials such as commercially available hemostats are able to support long-term in vivo tNSC viability. However, these matrices can pose a barrier to tNSC migration, resulting in insignificant tumor killing compared to tNSCs injected in PBS alone. Thus, we discovered that a balance between enhanced tNSC viability and unimpaired cell migration must be reached to optimize tNSCs for long-term GBM therapy. To do so, we will develop a novel adaptation of the 3D printing technology, continuous liquid interface production (CLIP), in which tNSCs are 3D printed into hydrogels in a process known as bioprinting. This results in cell-embedded 3D hydrogels which could be implanted into the GBM resection cavity without any intermediate cell seeding steps. We have shown that bioprinted cell-laden hydrogels exhibit higher seeding consistency than cells seeded externally onto hydrogel surfaces. However, cell behavior and function has not been characterized or optimized inside bioprinted hydrogels. Moreover, the most biocompatible hydrogels which support the longest cell viability exhibit the lowest printing resolution. Thus, we propose to optimize this novel bioprinting strategy by developing a biocompatible and printable resin that can support cell viability for at least one month. Furthermore, we will characterize cell health and functionality pre- and post-bioprinting to ensure that toxic resin monomers and UV light have not compromised the efficacy or safety of the embedded cells. Finally, we will characterize the efficacy of cell-laden bioprinted hydrogels in a post-resection GBM mouse ...