Traumatic brain injury (TBI) affects more than 10 million individuals worldwide each year and results in long- term motor, cognitive, and affective deficits. Pharmacologic strategies are often used to treat TBI but to date no therapy has successfully translated to the clinic, which advocates for other rehabilitative strategies to restore neuronal networks and recover behavioral deficits thereby increasing the probability of bench-to-bedside success. Neural stem cell (NSC) therapies may be a feasible alternative to pharmacotherapies for improving function after TBI. NSC-based therapies can exploit their inherent ability to migrate to stimulate regeneration and repair damaged brain tissue. In our pilot studies, well-characterized allogeneic human NSCs, LM-NSC008, genetically modified to express the human L-Myc gene were intranasally (IN) administered to adult male and female rats after cortical impact injury. LM-NSC008 cells migrated toward and distributed throughout damaged brain tissue and into distant regions mediating behavioral changes. LM-NSC008 cells significantly improved two distinct cognitive domains - spatial learning (reference learning) and executive function vs. vehicle (VEH). Because clinical translation has been unsuccessful with single therapies, the NIH’s TBI and combination therapy workshop recommended the evaluation of combination treatments. We have reported synergistic benefits when environmental enrichment (EE) is combined with pharmacotherapies and predict augmented benefits with LM-NSC008 cells as well. Our hypotheses are that IN LM-NSC008 cells in male and female rats will 1) migrate and accumulate in sufficient quantities at proximal and distal TBI sites and contribute to behavioral recovery, 2) provide benefit with a clinically relevant delayed administration approach, and 3) improve recovery more robustly when combined with EE than when administered alone. To test our hypotheses, optimize IN delivery doses of LM-NSC008 cells, and to determine LM-NSC008 cell fate and mechanisms, alone and in combination with EE, the following Aims are proposed. Aim 1a: Determine the optimal dose and delivery protocol of IN LM-NSC008 cells for maximal distribution to areas of damage at early, delayed, and chronic time points after TBI. A single high dose of LM-NSC008 cells [6x106] or VEH will be given IN on day-7 (acute period), day-21 (delayed), or day-90 (chronic) after moderate TBI or sham injury, while six lower doses [1x106] will be given once on post-surgery days 7,9,11,13,15,17 (acute), 21,23,25,27,29,31 (delayed), or 90,92,94,96,98,100 (chronic) to determine the protocol that provides maximal distribution of cells at the trauma sites at 3 timepoints after TBI and significantly improves recovery. Aim 1b: Evaluate motor, cognitive, and affective behavioral improvements with IN LM-NSC008 cell therapy in TBI and sham rats. Aim 2: Determine the effect of combining IN LM-NSC008 cell therapy with EE on motor, cognitive, and affective behavior. Aim 3: Determine the fate, mechanisms, and regenerative capacity of IN administered LM-NSC008 cells alone or with EE after TBI.

Project Narrative The current lack of translatability with current pharmacologic strategies for traumatic brain injury (TBI) dictates that other therapeutic strategies be evaluated thereby increasing the probability of bench-to-bedside success. Neural stem cell therapies may be a feasible alternative to pharmacotherapies for improving function after TBI as they can exploit their inherent ability to migrate and stimulate endogenous repair mechanisms, and thus the proposed studies will use an established rat model of TBI to test LM-NSC008 cell migration, distribution, and therapeutic efficacy in both sexes. A rehabilitative approach is also included and consists of using environmental enrichment, a well validated preclinical model of neurorehabilitation combined with LM-NSC008 cells to accelerate clinical translation to patients with TBI.