Nishi, R. A. | bioRxiv Science

bioRxiv2026

Regenerative Neural Stem Cell Therapy Improves Multidomain Neurological Deficits after Traumatic Brain Injury in Nonhuman Primates

Traumatic brain injury (TBI) produces persistent multidomain disability spanning motor, cognitive, emotional and sleep-wake function, with no approved restorative therapy. Here, we tested pd.S6.133.hNSC, a cryopreserved, GMP-like human neural stem cell (hNSC) product derived from Shef-6 and FACS-sorted on CD133+/CD34-, in a randomized dose-ranging study in common marmosets subjected to controlled cortical impact (n = 18). Seven weeks after injury, animals received MRI-guided stereotactic transplantation into perilesional cortex bilaterally under tacrolimus immunosuppression, with either vehicle or pd.S6.133.hNSC at 1 million (1e6) or 5 million (5e6) cell dose. At 3 months post-transplantation, 5e6 dosage improved executive and problem-solving performances (Object Retrieval Task with Barrier Detour), gait dynamics (CatWalk assay), anxiety-like behavior (Human Intruder Test), and actigraphy-derived sleep-wake and circadian rhythm measures relative to vehicle and 1e6 dose. Longitudinal 7T MRI demonstrated a dose-dependent reduction in lesion volume and preservation of corpus callosum white matter volume in the 5e6 group. Transplantation was well tolerated, with no observed adverse events across 1,197 cumulative post-transplant animal-days. Histopathology at 3 months post-transplantation in NHPs showed engraftment without tumor formation or abnormal tissue overgrowth. These findings support the safety and multidomain efficacy of a cryopreserved hNSC product in a nonhuman primate TBI model and inform translational development toward first-in-human testing with clinically aligned endpoints.

neuroscience↗

bioRxiv2026

Microtubule Stabilization and Biomaterial Guidance Synergize to Enhance CST Regeneration and Motor Recovery After Chronic SCI.

Spinal cord injury (SCI) results in loss of sensory and motor function below the level of damage, with chronic injuries presenting unique challenges for regenerative therapies. While multichannel biomaterial interventions have shown promise in promoting axonal regeneration, circuit restoration, and motor recovery in acute SCI, achieving similar outcomes in chronic injury models remains challenging due to a combination of intrinsic and extrinsic factors. These include the reduced capacity of the neuronal cell body to sustain a growth-activated state and the formation of a physical and chemical barrier at the injury site, preventing axonal growth. To address these challenges and promote motor recovery after chronic injury, we investigated the combinatorial effect of two regenerative approaches: 1) the implantation of poly (lactide-co-glycolide) (PLG) biomaterial bridge to guide axonal growth through the injury site, and 2) the delivery of Epothilone B (EpoB), a microtubule stabilizer that strengthens axons to promote regrowth. We used a transgenic mouse model that selectively expresses a red fluorescent protein variant (tdTomato) reporter throughout the corticospinal tract (CST) under control of the Crym promoter (Crym-tdTomato). We demonstrated that the combination of bridge implantation 60 days after surgical hemisection at C5 with EpoB improved locomotor function. At 12 weeks post-bridge implantation, immunohistology revealed axon regeneration in mice receiving implantation, but not EpoB or no-implant controls. The addition of EpoB significantly increased the volume of both total and CST axons regenerating through the biomaterial channels. Diffusion tensor magnetic resonance imaging (DTI) analysis identified enhanced fractional anisotropy (FA), axial diffusivity (AD), and mean diffusivity (MD) in the bridge region in the combination treatment group, consistent with new intact axons. Furthermore, EpoB enhanced the myelination of regenerated axons in the bridge. Finally, we investigated the proteomic profile of corticospinal neurons ipsilateral and contralateral to the SCI lesion and bridge, comparing the effect of EpoB treatment. Mass spectrometry-based analysis of laser-captured cells in this paradigm identified activation of a regeneration program by corticospinal neurons. These findings present a novel approach to enhance regenerative neural repair and locomotor recovery in chronic SCI.

neuroscience↗