NSI-189 phosphate, a novel neurogenic compound, selectively benefits moderately depressed patients: A post-hoc analysis of a phase 2 study of major depressive disorder.

BACKGROUND: NSI-189 phosphate (NSI-189) is a novel neurogenic molecule with pleiotropic properties, including antidepressant, procognitive, synaptoplastic, and neurotrophic activities demonstrated in preclinical studies. Its antidepressant activity is monoamine-independent. NSI-189 was previously tested in patients with recurrent major depressive disorder in an inpatient setting. METHODS: This study involved 220 patients randomized to an NSI-189 40-mg dose, NSI-189 80-mg dose, or placebo daily for 12 weeks. The study utilized the sequential parallel comparison design, in which the drug effect was tested in 2 separate stages of 6 weeks each. Herein, post-hoc analyses of the data are presented. RESULTS: NSI-189's antidepressant effect increased when the participants' initial baseline depression severity was dichotomized along a Montgomery-Åsberg Depression Rating Scale (MADRS) score of 30. The NSI-189 80-mg dose showed significant benefit over placebo when utilizing the MADRS-6 (P = .046) in the subgroup of patients who were moderately depressed (MADRS < 30) but was not significant in patients who were severely depressed (MADRS ≥30). More pronounced procognitive effects were also observed in the moderate subgroup relative to the severe subgroup or the whole study group, in which 11/36 (31%), 5/36 (14%), or 7/36 (19%) of CogScreen variables significantly improved, respectively. CONCLUSIONS: These results suggest that NSI-189 is effective as a safe adjunctive therapy, with most compelling antidepressant and procognitive benefits noted in patients with moderate depression.

NSI-189, a small molecule with neurogenic properties, exerts behavioral, and neurostructural benefits in stroke rats.

Enhancing neurogenesis may be a powerful stroke therapy. Here, we tested in a rat model of ischemic stroke the beneficial effects of NSI-189, an orally active, new molecular entity (mol. wt. 366) with enhanced neurogenic activity, and indicated as an anti-depressant drug in a clinical trial (Fava et al., , Molecular Psychiatry, DOI: 10.1038/mp.2015.178) and being tested in a Phase 2 efficacy trial (ClinicalTrials.gov, , ClinicalTrials.gov Identifier: NCT02695472) for treatment of major depression. Oral administration of NSI-189 in adult Sprague-Dawley rats starting at 6 hr after middle cerebral artery occlusion, and daily thereafter over the next 12 weeks resulted in significant amelioration of stroke-induced motor and neurological deficits, which was maintained up to 24 weeks post-stroke. Histopathological assessment of stroke brains from NSI-189-treated animals revealed significant increments in neurite outgrowth as evidenced by MAP2 immunoreactivity that was prominently detected in the hippocampus and partially in the cortex. These results suggest NSI-189 actively stimulated remodeling of the stroke brain. Parallel in vitro studies further probed this remodeling process and demonstrated that oxygen glucose deprivation and reperfusion (OGD/R) initiated typical cell death processes, which were reversed by NSI-189 treatment characterized by significant attenuation of OGD/R-mediated hippocampal cell death and increased Ki67 and MAP2 expression, coupled with upregulation of neurogenic factors such as BDNF and SCF. These findings support the use of oral NSI-189 as a therapeutic agent well beyond the initial 6-hr time window to accelerate and enhance the overall functional improvement in the initial 6 months post stroke.

Autocrine production of IGF-I increases stem cell-mediated neuroprotection.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder resulting in motor neuron (MN) loss. There are currently no effective therapies; however, cellular therapies using neural progenitor cells protect MNs and attenuate disease progression in G93A-SOD1 ALS rats. Recently, we completed a phase I clinical trial examining intraspinal human spinal stem cell (HSSC) transplantation in ALS patients which demonstrated our approach was safe and feasible, supporting the phase II trial currently in progress. In parallel, efforts focused on understanding the mechanisms underlying the preclinical benefit of HSSCs in vitro and in animal models of ALS led us to investigate how insulin-like growth factor-I (IGF-I) production contributes to cellular therapy neuroprotection. IGF-I is a potent growth factor with proven efficacy in preclinical ALS studies, and we contend that autocrine IGF-I production may enhance the salutary effects of HSSCs. By comparing the biological properties of HSSCs to HSSCs expressing sixfold higher levels of IGF-I, we demonstrate that IGF-I production augments the production of glial-derived neurotrophic factor and accelerates neurite outgrowth without adversely affecting HSSC proliferation or terminal differentiation. Furthermore, we demonstrate that increased IGF-I induces more potent MN protection from excitotoxicity via both indirect and direct mechanisms, as demonstrated using hanging inserts with primary MNs or by culturing with organotypic spinal cord slices, respectively. These findings support our theory that combining autocrine growth factor production with HSSC transplantation may offer a novel means to achieve additive neuroprotection in ALS.

Feasibility of Three-Dimensional Placement of Human Therapeutic Stem Cells Using the Intracerebral Microinjection Instrument.

OBJECTIVES: The ability to safely place viable intracerebral grafts of human-derived therapeutic stem cells in three-dimensional (3D) space was assessed in a porcine model of human stereotactic surgery using the Intracerebral Microinjection Instrument (IMI) compared to a conventional straight cannula. MATERIALS AND METHODS: Two groups of healthy minipigs received injections of the human stem cell line, NSI-566, into the right hemisphere and cell suspension carrier media into the left hemisphere. Group A received all injections using a straight, 21-gauge stainless steel cannula. Group B received all injections using the IMI, whereby radial distribution of injections was achieved via angular extension of a 196-micron diameter cannula from a single overlying penetration of the guide cannula. Each animal received six 20 µL intracerebral-injections within each hemisphere: three in a radial distribution, covering a 180° arc with each injection separated by a 60° arc distance, within both frontal cortex and basal ganglia. H&E and immunocytochemistry (HuNu and GFAP) were used to identify implanted cells and to assess tissue response. RESULTS: The presence of surviving cells in appropriate brain regions demonstrated that the IMI is capable of accurately delivering viable human-derived stem cells safely in a 3D array at predetermined sites within the pig brain. In addition, qualitative evaluation of the target tissue suggests efficient delivery with decreased surgical trauma. CONCLUSIONS: In contrast to traditional straight cannulas, the IMI enables the delivery of multiple precise cellular injection volumes in accurate 3D arrays. In this porcine large animal model of human neurosurgery, the IMI reduced surgical time and appeared to reduce neural trauma associated with multiple penetrations that would otherwise be required using a conventional straight delivery cannula.

Intraspinal neural stem cell transplantation in amyotrophic lateral sclerosis: phase 1 trial outcomes.

OBJECTIVE: The US Food and Drug Administration-approved trial, "A Phase 1, Open-Label, First-in-Human, Feasibility and Safety Study of Human Spinal Cord-Derived Neural Stem Cell Transplantation for the Treatment of Amyotrophic Lateral Sclerosis, Protocol Number: NS2008-1," is complete. Our overall objective was to assess the safety and feasibility of stem cell transplantation into lumbar and/or cervical spinal cord regions in amyotrophic lateral sclerosis (ALS) subjects. METHODS: Preliminary results have been reported on the initial trial cohort of 12 ALS subjects. Here, we describe the safety and functional outcome monitoring results for the final trial cohort, consisting of 6 ALS subjects receiving 5 unilateral cervical intraspinal neural stem cell injections. Three of these subjects previously received 10 total bilateral lumbar injections as part of the earlier trial cohort. All injections utilized a novel spinal-mounted stabilization and injection device to deliver 100,000 neural stem cells per injection, for a dosing range up to 1.5 million cells. Subject assessments included detailed pre- and postsurgical neurological outcome measures. RESULTS: The cervical injection procedure was well tolerated and disease progression did not accelerate in any subject, verifying the safety and feasibility of cervical and dual-targeting approaches. Analyses on outcome data revealed preliminary insight into potential windows of stem cell biological activity and identified clinical assessment measures that closely correlate with ALS Functional Rating Scale-Revised scores, a standard assessment for ALS clinical trials. INTERPRETATION: This is the first report of cervical and dual-targeted intraspinal transplantation of neural stem cells in ALS subjects. This approach is feasible and well-tolerated, supporting future trial phases examining therapeutic dosing and efficacy.

Lumbar intraspinal injection of neural stem cells in patients with amyotrophic lateral sclerosis: results of a phase I trial in 12 patients.

Advances in stem cell biology have generated intense interest in the prospect of transplanting stem cells into the nervous system for the treatment of neurodegenerative diseases. Here, we report the results of an ongoing phase I trial of intraspinal injections of fetal-derived neural stems cells in patients with amyotrophic lateral sclerosis (ALS). This is a first-in-human clinical trial with the goal of assessing the safety and tolerability of the surgical procedure, the introduction of stem cells into the spinal cord, and the use of immunosuppressant drugs in this patient population. Twelve patients received either five unilateral or five bilateral (10 total) injections into the lumbar spinal cord at a dose of 100,000 cells per injection. All patients tolerated the treatment without any long-term complications related to either the surgical procedure or the implantation of stem cells. Clinical assessments ranging from 6 to 18 months after transplantation demonstrated no evidence of acceleration of disease progression due to the intervention. One patient has shown improvement in his clinical status, although these data must be interpreted with caution since this trial was neither designed nor powered to measure treatment efficacy. These results allow us to report success in achieving the phase I goal of demonstrating safety of this therapeutic approach. Based on these positive results, we can now advance this trial by testing intraspinal injections into the cervical spinal cord, with the goal of protecting motor neuron pools affecting respiratory function, which may prolong life for patients with ALS.

An immune deficient mouse model for mucopolysaccharidosis IIIA (Sanfilippo syndrome).

Mucopolysaccharidosis III (MPSIII, Sanfilippo syndrome) is a devastating lysosomal storage disease that primarily affects the central nervous system. MPSIIIA is caused by loss-of-function mutations in the gene coding for sulfamidase (N-sulfoglucosamine sulfohydrolase/SGSH) resulting in SGSH enzyme deficiency, a buildup of heparin sulfate and subsequent neurodegeneration. There is currently no cure or disease modifying treatment for MPSIIIA. A mouse model for MPSIIIA was characterized in 1999 and later backcrossed onto the C57BL/6 background. In the present study, a novel immune deficient MPSIIIA mouse model (MPSIIIA-TKO) was created by backcrossing the immune competent, C57BL/6 MPSIIIA mouse to an immune deficient mouse model lacking Rag2, CD47 and Il2rg genes. The resulting mouse model has undetectable SGSH activity, exhibits histological changes consistent with MPSIIIA and lacks T cells, B cells and NK cells. This new mouse model has the potential to be extremely useful in testing human cellular therapies in an animal model as it retains the MPSIIIA disease phenotype while tolerating xenotransplantation.

First Human Trial of Stem Cell Transplantation in Complex Arrays for Stroke Patients Using the Intracerebral Microinjection Instrument.

BACKGROUND: In preclinical studies, the Intracerebral Microinjection Instrument (IMI) has demonstrated the ability to deliver therapeutics within the brain in 3-dimensional arrays from a single overlying penetration while incurring minimal localized trauma. OBJECTIVE: To evaluate the safety and performance of the IMI in its first use in humans to deliver stem cells in complex configurations within brain regions affected by ischemic injury. METHODS: As part of a phase 1 study, 3 chronically hemiparetic motor stroke patients received intracerebral grafts of the therapeutic stem cell line, NSI-566, using the IMI and its supporting surgical planning software. The patients were 37 to 54 yr old, had ischemic strokes more than 1 yr prior to transplantation, and received Fugl-Meyer motor scale scores of 17-48 at screening. During a single surgical procedure, patients received several neural grafts (42 ± 3) within the peri-infarct region targeted strategically to facilitate neural repair. RESULTS: The IMI enabled multiple cellular deposits to be safely placed peripheral to stroke lesions. The procedure was well tolerated, recovery was uneventful, and there occurred no subsequent complications. The IMI performed reliably throughout the procedures without evident targeting errors. One year after transplantation, all 3 subjects displayed significant clinical improvement, and imaging analysis demonstrated occupation of infarct cavities with new tissue without tumor formation. CONCLUSION: IMI technology permits unprecedented numbers of injections to be tactically placed in 3-dimensional arrays safely and reliably in human subjects.This advanced methodology can optimize the benefits of novel therapeutics by enabling versatile 3-dimensional intracerebral targeting.

Spinal parenchymal occupation by neural stem cells after subpial delivery in adult immunodeficient rats.

Neural precursor cells (NSCs) hold great potential to treat a variety of neurodegenerative diseases and injuries to the spinal cord. However, current delivery techniques require an invasive approach in which an injection needle is advanced into the spinal parenchyma to deliver cells of interest. As such, this approach is associated with an inherent risk of spinal injury, as well as a limited delivery of cells into multiple spinal segments. Here, we characterize the use of a novel cell delivery technique that employs single bolus cell injections into the spinal subpial space. In immunodeficient rats, two subpial injections of human NSCs were performed in the cervical and lumbar spinal cord, respectively. The survival, distribution, and phenotype of transplanted cells were assessed 6-8 months after injection. Immunofluorescence staining and mRNA sequencing analysis demonstrated a near-complete occupation of the spinal cord by injected cells, in which transplanted human NSCs (hNSCs) preferentially acquired glial phenotypes, expressing oligodendrocyte (Olig2, APC) or astrocyte (GFAP) markers. In the outermost layer of the spinal cord, injected hNSCs differentiated into glia limitans-forming astrocytes and expressed human-specific superoxide dismutase and laminin. All animals showed normal neurological function for the duration of the analysis. These data show that the subpial cell delivery technique is highly effective in populating the entire spinal cord with injected NSCs, and has a potential for clinical use in cell replacement therapies for the treatment of ALS, multiple sclerosis, or spinal cord injury.

Enhancement of synaptic plasticity and reversal of impairments in motor and cognitive functions in a mouse model of Angelman Syndrome by a small neurogenic molecule, NSI-189.

NSI-189 Phosphate, (4-benzylpiperazin-1-yl)-[2-(3-methyl-butylamino)pyridin-3-yl] methanone is a new chemical entity under development for the treatment of MDD, based upon preclinical data demonstrating stimulation of neurogenesis of human hippocampus-derived neural stem cells in vitro and in mouse hippocampus in vivo. Previous studies have examined the tolerability and efficacy of NSI-189 for treating major depressive disorder (MDD). NSI-189 has shown significant potential as a treatment for MDD, with concurrent improvement of a cognition scale in a small double-blind, placebo-controlled study. The current study evaluated its possible application for the treatment of Angelman Syndrome. Incubation of acute hippocampal slices from wild-type mice with NSI-189 resulted in a time- and dose-dependent increase in the magnitude of long-term potentiation (LTP) elicited by theta burst stimulation (TBS). The same protocol enhanced TBS-induced LTP in acute hippocampal slices from AS mice. A short treatment with daily injections of NSI-189 in AS mice reversed impairments in cognitive and motor functions, while it slightly enhanced performance of WT mice. The effects of NSI-189 on synaptic plasticity and cognitive functions were associated with activation of the TrkB and Akt pathways. These results suggest that NSI-189 could represent a potential treatment for AS patients.

Amelioration of Both Central and Peripheral Neuropathy in Mouse Models of Type 1 and Type 2 Diabetes by the Neurogenic Molecule NSI-189.

While peripheral neuropathy is the most common complication of long-term diabetes, cognitive deficits associated with encephalopathy and myelopathy also occur. Diabetes is a risk factor for Alzheimer disease (AD) and increases the risk of progression from mild cognitive impairment to AD. The only current recommendation for preventing or slowing the progression of peripheral neuropathy is to maintain close glycemic control, while there is no recommendation for central nervous system disorders. NSI-189 is a new chemical entity that when orally administered promotes neurogenesis in the adult hippocampus, increases hippocampal volume, enhances synaptic plasticity, and reduces cognitive dysfunction. To establish the potential for impact on peripheral neuropathy, we first showed that NSI-189 enhances neurite outgrowth and mitochondrial functions in cultured adult rat primary sensory neurons. Oral delivery of NSI-189 to murine models of type 1 (female) and type 2 (male) diabetes prevented multiple functional and structural indices of small and large fiber peripheral neuropathy, increased hippocampal neurogenesis, synaptic markers and volume, and protected long-term memory. NSI-189 also halted progression of established peripheral and central neuropathy. NSI-189, which is currently in clinical trials for treatment of major depressive disorder, offers the opportunity for the development of a single therapeutic agent against multiple indices of central and peripheral neuropathy.

Feasibility of Human Neural Stem Cell Transplantation for the Treatment of Acute Subdural Hematoma in a Rat Model: A Pilot Study.

Human neural stem cells (hNSCs) transplantation in several brain injury models has established their therapeutic potential. However, the feasibility of hNSCs transplantation is still not clear for acute subdural hematoma (ASDH) brain injury that needs external decompression. Thus, the aim of this pilot study was to test feasibility using a rat ASDH decompression model with two clinically relevant transplantation methods. Two different methods, in situ stereotactic injection and hNSC-embedded matrix seating on the brain surface, were attempted. Athymic rats were randomized to uninjured or ASDH groups (F344/NJcl-rnu/rnu, n = 7-10/group). Animals in injury group were subjected to ASDH, and received decompressive craniectomy and 1-week after decompression surgery were transplanted with green fluorescent protein (GFP)-transduced hNSCs using one of two approaches. Histopathological examinations at 4 and 8 weeks showed that the GFP-positive hNSCs survived in injured brain tissue, extended neurite-like projections resembling neural dendrites. The in situ transplantation group had greater engraftment of hNSCs than matrix embedding approach. Immunohistochemistry with doublecortin, NeuN, and GFAP at 8 weeks after transplantation showed that transplanted hNSCs remained as immature neurons and did not differentiate toward to glial cell lines. Motor function was assessed with rotarod, compared to control group (n = 10). The latency to fall from the rotarod in hNSC in situ transplanted rats was significantly higher than in control rats (median, 113 s in hNSC vs. 69 s in control, P = 0.02). This study first demonstrates the robust engraftment of in situ transplanted hNSCs in a clinically-relevant ASDH decompression rat model. Further preclinical studies with longer study duration are warranted to verify the effectiveness of hNSC transplantation in amelioration of TBI induced deficits.

Targeted intraspinal injections to assess therapies in rodent models of neurological disorders.

Despite decades of research, pharmacological therapies for spinal cord motor pathologies are limited. Alternatives using macromolecular, viral, or cell-based therapies show early promise. However, introducing these substances into the spinal cord, past the blood-brain barrier, without causing injury is challenging. We describe a technique for intraspinal injection targeting the lumbar ventral horn in rodents. This technique preserves motor performance and has a proven track record of translation into phase 1 and 2 clinical trials in amyotrophic lateral sclerosis (ALS) patients. The procedure, in brief, involves exposure of the thoracolumbar spine and dissection of paraspinous muscles over the target vertebrae. Following laminectomy, the spine is affixed to a stereotactic frame, permitting precise and reproducible injection throughout the lumbar spine. We have used this protocol to inject various stem cell types, primarily human spinal stem cells (HSSCs); however, the injection is adaptable to any candidate therapeutic cell, virus, or macromolecule product. In addition to a detailed procedure, we provide stereotactic coordinates that assist in targeting of the lumbar spine and instructional videos. The protocol takes ~2 h per animal.

Stable Intracerebral Transplantation of Neural Stem Cells for the Treatment of Paralysis Due to Ischemic Stroke.

NSI-566 is a stable, primary adherent neural stem cell line derived from a single human fetal spinal cord and expanded epigenetically with no genetic modification. This cell line is being tested in clinical trials in the U.S. for treatment of amyotrophic lateral sclerosis and spinal cord injury. In a single-site, phase I study, we evaluated the feasibility and safety of NSI-566 transplantation for the treatment of hemiparesis due to chronic motor stroke and determined the maximum tolerated dose for future trials. Three cohorts (n = 3 per cohort) were transplanted with one-time intracerebral injections of 1.2 × 107 , 2.4 × 107 , or 7.2 × 107 cells. Immunosuppression therapy with tacrolimus was maintained for 28 days. All subjects had sustained chronic motor strokes, verified by magnetic resonance imaging (MRI), initiated between 5 and 24 months prior to surgery with modified Rankin Scores [MRSs] of 2, 3, or 4 and Fugl-Meyer Motor Scores of 55 or less. At the 12-month visit, the mean Fugl-Meyer Motor Score (FMMS, total score of 100) for the nine participants showed 16 points of improvement (p = .0078), the mean MRS showed 0.8 points of improvement (p = .031), and the mean National Institutes of Health Stroke Scale showed 3.1 points of improvement (p = .020). For six participants who were followed up for 24 months, these mean changes remained stable. The treatment was well tolerated at all doses. Longitudinal MRI studies showed evidence indicating cavity-filling by new neural tissue formation in all nine patients. Although this was a small, one-arm study of feasibility, the results are encouraging to warrant further studies. Stem Cells Translational Medicine 2019;8:999-1007.

ATM-mediated response to DNA double strand breaks in human neurons derived from stem cells.

Ataxia-telangiectasia (A-T) is a multi-system genomic instability syndrome that is caused by loss or inactivation of the ATM protein kinase. ATM is largely nuclear in proliferating cells, and activates an extensive network of pathways in response to double strand breaks (DSBs) in the DNA by phosphorylating key proteins in these pathways. The prominent symptom of A-T is neuronal degeneration, making the elucidation of ATM's functions in neurons essential to understanding the disease. It has been suggested that ATM is cytoplasmic in neurons and functions in processes that are not associated with the DNA damage response. Recently we showed that in human neuron-like cells obtained by in vitro differentiation of neuroblastomas, ATM was largely nuclear and mediated the DSB response as in proliferating cells. We have now extended these studies to two additional model systems: neurons derived from human embryonic stem cells, and cortical neurons derived from neural stem cells. The results substantiate the notion that ATM is nuclear in human neurons and mediates the DSB response, the same as it does in proliferating cells. We present here unique and powerful model systems to further study the ATM-mediated network in neurons.

Effects of Sertoli cell-conditioned medium on ventral midbrain neural stem cells: a preliminary report.

The 796RMB cell line is a multipotent stem cell line isolated from human fetal midbrain tissues, a region from which dopamine neurons of the substantia nigra develop. It would be useful to increase the dopaminergic characteristics of this cell line to enhance its usefulness as a cell therapy for Parkinson's disease utilizing transplantation protocols. Sertoli cells and its conditioned media isolated from the testis have been previously shown to enhance tyrosine hydroxylase expression in ventral mesencephalon neurons both in vitro and in vivo. Therefore, the present preliminary study investigated the ability of Sertoli cell pre-conditioned medium to enhance differentiation of the 796MB cell line toward the domaminergic phenotype. Results showed that secretory products derived from Sertoli cell conditioned medium increased cell proliferation and enhanced dopaminergic neuronal differentiation of the 796RMB cell line. These findings may lead to alternative therapeutic cell transplantation protocols for the treatment of Parkinson's disease.

Human neural stem cell transplantation improves cognition in a murine model of Alzheimer's disease.

Stem cell transplantation offers a potentially transformative approach to treating neurodegenerative disorders. The safety of cellular therapies is established in multiple clinical trials, including our own in amyotrophic lateral sclerosis. To initiate similar trials in Alzheimer's disease, efficacious cell lines must be identified. Here, we completed a preclinical proof-of-concept study in the APP/PS1 murine model of Alzheimer's disease. Human neural stem cell transplantation targeted to the fimbria fornix significantly improved cognition in two hippocampal-dependent memory tasks at 4 and 16 weeks post-transplantation. While levels of synapse-related proteins and cholinergic neurons were unaffected, amyloid plaque load was significantly reduced in stem cell transplanted mice and associated with increased recruitment of activated microglia. In vitro, these same neural stem cells induced microglial activation and amyloid phagocytosis, suggesting an immunomodulatory capacity. Although long-term transplantation resulted in significant functional and pathological improvements in APP/PS1 mice, stem cells were not identified by immunohistochemistry or PCR at the study endpoint. These data suggest integration into native tissue or the idea that transient engraftment may be adequate for therapeutic efficacy, reducing the need for continued immunosuppression. Overall, our results support further preclinical development of human neural stem cells as a safe and effective therapy for Alzheimer's disease.

Remediation of Radiation-Induced Cognitive Dysfunction through Oral Administration of the Neuroprotective Compound NSI-189.

Clinical management of primary and secondary central nervous system (CNS) malignancies frequently includes radiotherapy to forestall tumor growth and recurrence after surgical resection. While cranial radiotherapy remains beneficial, adult and pediatric brain tumor survivors suffer from a wide range of debilitating and progressive cognitive deficits. Although this has been recognized as a significant problem for decades, there remains no clinical recourse for the unintended neurocognitive sequelae associated with these types of cancer treatments. In previous work, multiple mechanisms have been identified that contribute to radiation-induced cognitive dysfunction, including the inhibition of neurogenesis caused by the depletion of radiosensitive populations of stem and progenitor cells in the hippocampus. To explore the potential neuroprotective properties of a pro-neurogenic compound NSI-189, Long-Evans rats were subjected to a clinically relevant fractionated irradiation protocol followed by four weeks of NSI-189 administered daily by oral gavage. Animals were then subjected to five different behavioral tasks followed by an analysis of neurogenesis, hippocampal volume and neuroinflammation. Irradiated cohorts manifested significant behavioral decrements on all four spontaneous exploration tasks. Importantly, NSI-189 treatment resulted in significantly improved performance in four of these tasks: novel place recognition, novel object recognition, object in place and temporal order. In addition, there was a trend of improved performance in the contextual phase of the fear conditioning task. Importantly, enhanced cognition in the NSI-189-treated cohort was found to persist one month after the cessation of drug treatment. These neurocognitive benefits of NSI-189 coincided with a significant increase in neurogenesis and a significant decrease in the numbers of activated microglia compared to the irradiated cohort that was given vehicle alone. The foregoing changes were not accompanied by major changes in hippocampal volume. These data demonstrate that oral administration of a pro-neurogenic compound exhibiting anti-inflammatory indications could impart long-term neurocognitive benefits in the irradiated brain.

Long-term Phase 1/2 intraspinal stem cell transplantation outcomes in ALS.

OBJECTIVE: Intraspinal human spinal cord-derived neural stem cell (HSSC) transplantation is a potential therapy for amyotrophic lateral sclerosis (ALS); however, previous trials lack controls. This post hoc analysis compared ambulatory limb-onset ALS participants in Phase 1 and 2 (Ph1/2) open-label intraspinal HSSC transplantation studies up to 3 years after transplant to matched participants in Pooled Resource Open-Access ALS Clinical Trials (PRO-ACT) and ceftriaxone datasets to provide required analyses to inform future clinical trial designs. METHODS: Survival, ALSFRS-R, and a composite statistic (ALS/SURV) combining survival and ALS Functional Rating Scale revised (ALSFRS-R) functional status were assessed for matched participant subsets: PRO-ACT n = 1108, Ph1/2 n = 21 and ceftriaxone n = 177, Ph1/2 n = 20. RESULTS: Survival did not differ significantly between cohorts: Ph1/2 median survival 4.7 years, 95% CI (1.2, ∞) versus PRO-ACT 2.3 years (1.9, 2.5), P = 1.0; Ph1/2 3.0 years (1.2, 5.6) versus ceftriaxone 2.3 years (1.8, 2.8), P = 0.88. Mean ALSFRS-R at 24 months significantly differed between Ph1/2 and both comparison cohorts (Ph1/2 30.1 ± 8.6 vs. PRO-ACT 24.0 ± 10.2, P = 0.048; Ph1/2 30.7 ± 8.8 vs. ceftriaxone 19.2 ± 9.5, P = 0.0023). Using ALS/SURV, median PRO-ACT and ceftriaxone participants died by 24 months, whereas median Ph1/2 participant ALSFRS-Rs were 23 (P = 0.0038) and 19 (P = 0.14) in PRO-ACT and ceftriaxone comparisons at 24 months, respectively, supporting improved functional outcomes in the Ph1/2 study. INTERPRETATION: Comparison of Ph1/2 studies to historical datasets revealed significantly improved survival and function using ALS/SURV versus PRO-ACT controls. While results are encouraging, comparison against historical populations demonstrate limitations in noncontrolled studies. These findings support continued evaluation of HSSC transplantation in ALS, support the benefit of control populations, and enable necessary power calculations to design a randomized, sham surgery-controlled efficacy study.

Extensive neuronal differentiation of human neural stem cell grafts in adult rat spinal cord.

BACKGROUND: Effective treatments for degenerative and traumatic diseases of the nervous system are not currently available. The support or replacement of injured neurons with neural grafts, already an established approach in experimental therapeutics, has been recently invigorated with the addition of neural and embryonic stem-derived precursors as inexhaustible, self-propagating alternatives to fetal tissues. The adult spinal cord, i.e., the site of common devastating injuries and motor neuron disease, has been an especially challenging target for stem cell therapies. In most cases, neural stem cell (NSC) transplants have shown either poor differentiation or a preferential choice of glial lineages. METHODS AND FINDINGS: In the present investigation, we grafted NSCs from human fetal spinal cord grown in monolayer into the lumbar cord of normal or injured adult nude rats and observed large-scale differentiation of these cells into neurons that formed axons and synapses and established extensive contacts with host motor neurons. Spinal cord microenvironment appeared to influence fate choice, with centrally located cells taking on a predominant neuronal path, and cells located under the pia membrane persisting as NSCs or presenting with astrocytic phenotypes. Slightly fewer than one-tenth of grafted neurons differentiated into oligodendrocytes. The presence of lesions increased the frequency of astrocytic phenotypes in the white matter. CONCLUSIONS: NSC grafts can show substantial neuronal differentiation in the normal and injured adult spinal cord with good potential of integration into host neural circuits. In view of recent similar findings from other laboratories, the extent of neuronal differentiation observed here disputes the notion of a spinal cord that is constitutively unfavorable to neuronal repair. Restoration of spinal cord circuitry in traumatic and degenerative diseases may be more realistic than previously thought, although major challenges remain, especially with respect to the establishment of neuromuscular connections.