Grafts of Olfactory Stem Cells Restore Breathing and Motor Functions after Rat Spinal Cord Injury

Contrasting Experimental Rodent Aftercare With Human Clinical Treatment for Cervical Spinal Cord Injury: Bridging the Translational "Valley of Death"

More than half of all spinal cord injuries (SCIs) occur at the cervical level and often lead to life-threatening breathing motor dysfunction. The C2 hemisection (C2Hx) and high cervical contusion mouse and rat models of SCI are widely utilized both to understand the pathological effects of SCI and to develop potential therapies. Despite rigorous research effort, pre-clinical therapeutics studied in those animal models of SCI sometimes fail when evaluated in the clinical setting. Differences between standard-of-care treatment for acute SCI administered to clinical populations and experimental animal models of SCI could influence the heterogeneity of outcome between pre-clinical and clinical studies. In this review, we have summarized both the standard clinical interventions used to treat patients with cervical SCI and the various veterinary aftercare protocols used to care for rats and mice after experimentally induced C2Hx and high cervical contusion models of SCI. Through this analysis, we have identified areas of marked dissimilarity between clinical and veterinary protocols and suggest the modification of pre-clinical animal care particularly with respect to analgesia, anticoagulative measures, and stress ulcer prophylaxis. In our discussion, we intend to inspire consideration of potential changes to aftercare for animal subjects of experimental SCI that may help to bridge the translational "Valley of Death" and ultimately contribute more effectively to finding treatments capable of restoring independent breathing function to persons with cervical SCI.

The Proteome Profile of Olfactory Ecto-Mesenchymal Stem Cells-Derived from Patients with Familial Alzheimer's Disease Reveals New Insights for AD Study

Alzheimer's disease (AD), the most common neurodegenerative disease and the first cause of dementia worldwide, has no effective treatment, and its pathological mechanisms are not yet fully understood. We conducted this study to explore the proteomic differences associated with Familial Alzheimer's Disease (FAD) in olfactory ecto-mesenchymal stem cells (MSCs) derived from PSEN1 (A431E) mutation carriers compared with healthy donors paired by age and gender through two label-free liquid chromatography-mass spectrometry approaches. The first analysis compared carrier 1 (patient with symptoms, P1) and its control (healthy donor, C1), and the second compared carrier 2 (patient with pre-symptoms, P2) with its respective control cells (C2) to evaluate whether the protein alterations presented in the symptomatic carrier were also present in the pre-symptom stages. Finally, we analyzed the differentially expressed proteins (DEPs) for biological and functional enrichment. These proteins showed impaired expression in a stage-dependent manner and are involved in energy metabolism, vesicle transport, actin cytoskeleton, cell proliferation, and proteostasis pathways, in line with previous AD reports. Our study is the first to conduct a proteomic analysis of MSCs from the Jalisco FAD patients in two stages of the disease (symptomatic and presymptomatic), showing these cells as a new and excellent in vitro model for future AD studies.

Therapeutic Strategies Targeting Respiratory Recovery after Spinal Cord Injury: From Preclinical Development to Clinical Translation

High spinal cord injuries (SCIs) lead to permanent functional deficits, including respiratory dysfunction. Patients living with such conditions often rely on ventilatory assistance to survive, and even those that can be weaned continue to suffer life-threatening impairments. There is currently no treatment for SCI that is capable of providing complete recovery of diaphragm activity and respiratory function. The diaphragm is the main inspiratory muscle, and its activity is controlled by phrenic motoneurons (phMNs) located in the cervical (C3-C5) spinal cord. Preserving and/or restoring phMN activity following a high SCI is essential for achieving voluntary control of breathing. In this review, we will highlight (1) the current knowledge of inflammatory and spontaneous pro-regenerative processes occurring after SCI, (2) key therapeutics developed to date, and (3) how these can be harnessed to drive respiratory recovery following SCIs. These therapeutic approaches are typically first developed and tested in relevant preclinical models, with some of them having been translated into clinical studies. A better understanding of inflammatory and pro-regenerative processes, as well as how they can be therapeutically manipulated, will be the key to achieving optimal functional recovery following SCIs.

Human nasal olfactory stem cells, purified as advanced therapy medicinal products, improve neuronal differentiation

BACKGROUND

Olfactory ecto-mesenchymal stem cells (OE-MSC) are mesenchymal stem cells derived from the lamina propria of the nasal mucosa. They display neurogenic and immunomodulatory properties and were shown to induce recovery in animal models of spinal cord trauma, hearing loss, Parkinsons's disease, amnesia, and peripheral nerve injury. As a step toward clinical practice, we sought to (i) devise a culture protocol that meets the requirements set by human health agencies and (ii) assess the efficacy of stem cells on neuron differentiation.

METHODS

Nasal olfactory mucosa biopsies from three donors were used to design and validate the good manufacturing process for purifying stem cells. All processes and procedures were performed by expert staff from the cell therapy laboratory of the public hospital of Marseille (AP-HM), according to aseptic handling manipulations. Premises, materials and air were kept clean at all times to avoid cross-contamination, accidents, or even fatalities. Purified stem cells were cultivated for 24 or 48 h and conditioned media were collected before being added to the culture medium of the neuroblastoma cell line Neuro2a.

RESULTS

Compared to the explant culture-based protocol, enzymatic digestion provides higher cell numbers more rapidly and is less prone to contamination. The use of platelet lysate in place of fetal calf serum is effective in promoting higher cell proliferation (the percentage of CFU-F progenitors is 15.5%), with the optimal percentage of platelet lysate being 10%. Cultured OE-MSCs do not show chromosomal rearrangement and, as expected, express the usual phenotypic markers of mesenchymal stem cells. When incorporated in standard culture medium, the conditioned medium of purified OE-MSCs promotes cell differentiation of Neuro2a neuroblastoma cells.

CONCLUSION

We developed a safer and more efficient manufacturing process for clinical grade olfactory stem cells. With this protocol, human OE-MSCs will soon be used in a Phase I clinical based on their autologous transplantation in digital nerves with a neglected injury. However, further studies are required to unveil the underlying mechanisms of action.

Respiratory plasticity following spinal cord injury: perspectives from mouse to man

The study of respiratory plasticity in animal models spans decades. At the bench, researchers use an array of techniques aimed at harnessing the power of plasticity within the central nervous system to restore respiration following spinal cord injury. This field of research is highly clinically relevant. People living with cervical spinal cord injury at or above the level of the phrenic motoneuron pool at spinal levels C3-C5 typically have significant impairments in breathing which may require assisted ventilation. Those who are ventilator dependent are at an increased risk of ventilator-associated co-morbidities and have a drastically reduced life expectancy. Pre-clinical research examining respiratory plasticity in animal models has laid the groundwork for clinical trials. Despite how widely researched this injury is in animal models, relatively few treatments have broken through the preclinical barrier. The three goals of this present review are to define plasticity as it pertains to respiratory function post-spinal cord injury, discuss plasticity models of spinal cord injury used in research, and explore the shift from preclinical to clinical research. By investigating current targets of respiratory plasticity research, we hope to illuminate preclinical work that can influence future clinical investigations and the advancement of treatments for spinal cord injury.

Promoting motor functions in a spinal cord injury model of rats using transplantation of differentiated human olfactory stem cells: A step towards future therapy

Human olfactory ecto-mesenchymal stem cells (hOE-MSCs) derived from the human olfactory mucosa (OM) can be easily isolated and expanded in cultures while their immense plasticity is maintained. To mitigate ethical concerns, the hOE-MSCs can be also transplanted across allogeneic barriers, making them desirable cells for clinical applications. The main purpose of this study was to evaluate the effects of administering the hOE-MSCs on a spinal cord injury (SCI) model of rats. These cells were accordingly isolated and cultured, and then treated in the neurobasal medium containing serum-free Dulbecco's Modified Essential Medium (DMEM) and Ham's F-12 Medium (DMEM/F12) with 2% B27 for two days. Afterwards, the pre-induced cells were incubated in N2B27 with basic fibroblast growth factor (bFGF), fibroblast growth factor 8b (FGF8b), sonic hedgehog (SHH), and ascorbic acid (vitamin C) for six days. The efficacy of the induced cells was additionally evaluated using immunocytochemistry (ICC) and real-time polymerase chain reaction (RT-PCR). The differentiated cells were similarly transplanted into the SC contusions. Functional recovery was further conducted on a weekly basis for eight consecutive weeks. Moreover, cell integration was assessed via conventional histology and ICC, whose results revealed the expression of choline acetyltransferase (ChAT) marker at the induction stage. According to the RT-PCR findings, the highest expression level of insulin gene-enhancer protein (islet-1), oligodendrocyte transcription factor (Olig2), and homeobox protein HB9 was observed at the induction stage. The number of engraftment cells also rose (approximately by 2.5 % ± 0.1) in the motor neuron-like cells derived from the hOE-MSCs-grafted group compared with the OE-MSCs-grafted one. The functional analysis correspondingly revealed that locomotor and sensory scores considerably improved in the rats in the treatment group. These findings suggested that motor neuron-like cells derived from the hOE-MSCs could be utilized as an alternative cell-based therapeutic strategy for SCI.

Immunomodulatory Layered Double Hydroxide Nanoparticles Enable Neurogenesis by Targeting Transforming Growth Factor-β Receptor 2

Immune microenvironment amelioration and reconstruction by functional biomaterials has become a promising strategy for spinal cord injury (SCI) recovery. In this study, we evaluated the neural regeneration and immunoregulation functions of Mg/Al layered double hydroxide (Mg/Al-LDH) nanoparticles in completely transected and excised mice and revealed the immune-related mechanisms. LDH achieved significant performance in accelerating neural stem cells (NSCs) migration, neural differentiation, L-Ca²⁺ channel activation, and inducible action potential generation. In vivo, the behavioral and electrophysiological performance of SCI mice was significantly improved by LDH implantation, with BrdU⁺ endogenous NSCs and neurons clearly observed in the lesion sites. According to RNA-seq and ingenuity pathway analysis, transforming growth factor-β receptor 2 (TGFBR2) is the key gene through which LDH inhibits inflammatory responses and accelerates neural regeneration. Significant colocalization of TGFBR2 and LDH was found on the cell membranes of NSCs both in vitro and in vivo, and LDH increased the expression of TGF-β2 in NSCs and activated the proliferation of precursor neural cells. LDH decreased the expression of M1 markers and increased the expression of M2 markers in both microglia and bone marrow-derived macrophages, and these effects were reversed by a TGFBR2 inhibitor. In addition, as a carrier, LDH loaded with NT3 exhibited better recovery effects with regard to the basso mouse scale score, motor evoked potential performance, and regenerated neural cell numbers than LDH itself. Thus, we have developed Mg/Al-LDH that can be used to construct a suitable immune microenvironment for SCI recovery and have revealed the targeted receptor.

A pilot study of clinical cell therapy for patients with vascular dementia

Background:

Vascular dementia (VD) is a series of clinical and neurophysiological manifestations caused by cerebrovascular disease. As the human lifespan increases, the number of people affected by age-related dementia is growing at an alarming pace, but no proved therapeutic methods can stop it from getting worse.

Objective:

To investigate the neurorestorative effects of injecting olfactory ensheathing cells (OECs), Schwann cells (SCs), and olfactory receptor neurons (ORNs) into olfactory sub-mucosa in VD patients.

Methods:

A pilot study of double-blind randomized controlled cell therapies was conducted in VD patients (n = 5). Cells were injected into the patients’ olfactory sub-mucosa. Two patients received OEC treatment, one received SC treatment, one ORN treatment, and one OEC combined with ORN. Mental state and cognitive function were observed before treatment and 1, 3, 6, and 12 months after treatment. magnetic resonance imaging (MRI) or computed tomography (CT) was performed before treatment and 12 months after treatment.

Results:

The directional function score on the Mini-Mental Status Examination (MMSE) in the patient who received SC treatment had increased slightly 1 and 3 months after treatment. The scores for orientation, attention, delayed verbal recall, and repetition increased in the ORN group patient 1 month after treatment. The orientation and repetition scores of the ORN group patient continued to increase 3 months after treatment. The scores for attention, delayed verbal recall, and phase 3 command decreased in the OEC and the OEC + ORN group patients after treatment assessment Scores on the Montreal Cognitive Assessment (MoCA) and Clinical Dementia Rating (CDR) scale also improved in the ORN group patient. Clinical and MRI or CT examinations did not find any side effects from the cell therapy or transplanting procedure.

Conclusion:

All of the cell transplantations were found to be safe. ORN was shown to be a promising therapy for VD patients. Phase II clinical trials of ORN, SC, and OEC therapy are required to verify their effects on VD symptoms, especially ORNs.

Expansion of murine and human olfactory epithelium/mucosa colonies and generation of mature olfactory sensory neurons under chemically defined conditions

Olfactory dysfunctions, including hyposmia and anosmia, affect ~100 million people around the world and the underlying causes are not fully understood. Degeneration of olfactory sensory neurons and incapacity of globose basal cells to generate olfactory sensory neurons are found in elder people and patients with smell disorders. Thus, olfactory stem cell may function as a promising tool to replace inactivated globose basal cells and to generate sensory neurons. Methods: We established clonal expansion of cells from the murine olfactory epithelium as well as colony growth from human olfactory mucosa using Matrigel-based three-dimensional system. These colonies were characterized by immunostaining against olfactory epithelium cellular markers and by calcium imaging of responses to odors. Chemical addition was optimized to promote Lgr5 expression, colony growth and sensory neuron generation, tested by quantitative PCR and immunostaining against progenitor and neuronal markers. The differential transcriptomes in multiple signaling pathways between colonies under different base media and chemical cocktails were determined by RNA-Seq. Results: In defined culture media, we found that VPA and CHIR99021 induced the highest Lgr5 expression level, while LY411575 resulted in the most abundant yield of OMP⁺ mature sensory neurons in murine colonies. Different base culture media with drug cocktails led to apparent morphological alteration from filled to cystic appearance, accompanied with massive transcriptional changes in multiple signaling pathways. Generation of sensory neurons in human colonies was affected through TGF-β signaling, while Lgr5 expression and cell proliferation was regulated by VPA. Conclusion: Our findings suggest that targeting expansion of olfactory epithelium/mucosa colonies in vitro potentially results in discovery of new source to cell replacement-based therapy against smell loss.

Why is olfactory neuroepithelium?

Currently, most cellular therapeutic effects for nervous diseases cannot be proven in a multicenter, randomized, double-blind placebo-control clinical trials, except for a few kinds of cells such as olfactory ensheathing cells. These cells show significant improvements in functional recovery and quality of life for patients with chronic ischemic stroke. Also, olfactory neuron transplantation has promising neurorestorative effects on patients with vascular dementia. Human olfactory neuroepithelium can spontaneously and sustainably regenerate or produce new olfactory neurons and glial cell types for decades or a lifetime. The neurorestorative mechanisms of olfactory ensheathing cells are well known; however, little is known about the neurorestorative mechanisms of olfactory neurons. Therefore, I hypothesize that the neurorestorative mechanisms of olfactory neurons after transplantation: (1) can well migrate where they are needed and become local functional neurons, as they need to compensate or replace; (2) must be regulated by some special molecular factors to elongate their axons, modulate or direct synapses to correctly recognize and connect the target cells, and integrate functions. Based on olfactory neuroepithelium cells displaying the special characterization, neurorestorative mechanisms, clinical therapeutic achievements, and hypotheses of effective mechanisms, they (olfactory ensheathing cells and olfactory neurons) may be the most efficient instruments of neurorestoration.

A pilot study of clinical cell therapies in Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disease dominated by progressive cognitive dysfunction causing significant social, economic, and medical crises. Cell therapy has demonstrated favorable effects for AD. This pilot study examined the safety and neurorestorative effects of the olfactory ensheathing cell (OEC), olfactory neuron (ON), and Schwann cell (SC) on patients with AD. Seven patients with AD were enrolled in this two-center, randomized, double-blind, and placebo- controlled cell therapy study with a subsequent 12-month follow-up. We randomly assigned one or two participants in OEC, ON, and SC therapy or OEC combined with ON and placebo control. All enrolled patients were injected cells or medium into the olfactory sub-mucosa. They got an assessment of Mini-Mental State Examination, Montreal Cognitive Assessment, and Clinical Dementia Rating before treatment and 1, 3, 6, 12 months after treatment. We performed MRI or CT scans before treatment and 12 months after treatment. After integrating the results from the three evaluation methods, all cell types showed better results than a placebo control. ON and SC seem to exhibit more vital potential neurorestorative ability to enhance or convert the neurological functions of patients with AD, and OEC may help AD patients keep neurological functions stable. In this pilot study, there was no adverse or side-effect event. The results of this study strongly suggest conducting a phase II clinical trial of ON, SC, and OEC therapy to prove their neurorestorative effect on patients with AD.

Hypoxic conditioned promotes the proliferation of human olfactory mucosa mesenchymal stem cells and relevant lncRNA and mRNA analysis

AIMS

LncRNAs are involved in many biological processes, and hypoxia contributed to the alterations of lncRNAs. Hypoxic preconditioned olfactory mucosa mesenchymal stem cells (OM-MSCs) exerted stronger anti-apoptotic ability in models of disease, but the molecules that controlled different biological characteristics of human OM-MSCs between hypoxic and normoxic conditions were unclear. The present study was aimed to explore the molecules that controlled different biological characteristics of human OM-MSCs between hypoxic and normoxic conditions.

MAIN METHODS

LncRNAs and mRNAs expression profiles of human OM-MSCs between hypoxic (3%) and normoxic conditions were analyzed by Next-Generation Sequencing (NGS) analysis, bioinformatics analysis on these data were further performed. Moreover, loss-of function assay was conducted to investigate the impact of hypoxic condition on the proliferation and apoptosis of OM-MSCs.

KEY FINDINGS

Through the comparative analysis and bioinformatics analysis, a total of 1741 lncRNAs and 1603 mRNAs were significant differentially expressed in the hypoxia group compared with normoxia group. Enrichment analysis revealed that differentially expressed genes of human OM-MSCs mainly participated in cell cycle regulation, secretin of cytokines and so on. Meanwhile, hypoxic condition significantly promoted proliferation and inhibited apoptosis of human OM-MSCs, following loss-of-function assays confirmed that lncRNA DARS-AS1 were involved in this regulatory process by hypoxic condition. Further prediction of targeted genes and the construction of lncRNA-miRNA-mRNA interaction network enriched the significance regarding the mechanism of DARS-AS1.

SIGNIFICANCE

Altogether, these findings provided a new perspective for understanding the molecules expression patterns in hypoxia that contributed to corresponding phenotype alterations of OM-MSCs.

Bilateral striatal transplantation of human olfactory stem cells ameliorates motor function, prevents necroptosis-induced cell death and improves striatal volume in the rat model of Huntington's disease

Cellular transplant therapy is one of the most common therapeutic strategies used to mitigate symptoms of neurodegenerative diseases such as Huntington's disease (HD). Briefly, the main goal of the present study was to investigate HD's motor deficits through the olfactory ecto-mesenchymals stem cells (OE-MSC) secretome. OE-MSCs were characterized immunophenotypically by the positive expression of CD73, CD90 and CD105. Also, three specific markers of OE-MSCs were obtained from the nasal cavity of human volunteers. The main features of OE-MSCs are their high proliferation, ease of harvesting and growth factor secretion. All animals were randomly assigned to three groups: control, 3-NP + vehicle treated and 3-NP + Cell groups. In both experimental groups, the subjects received intraperitoneal 3-NP (30 mg/kg) injections once a day for five consecutive days, followed by the bilateral intra-striatal implantation of OE-MSCs in the 3-NP + Cell group. Muscular function was assessed by electromyography and rotarod test, and the locomotor function was evaluated using the open field test. According to our findings, striatal transplants of OE-MSCs reduced microglial inflammatory factor, the tumor necrosis factor (TNFα) in the 3-NP + Cell group, with a significant reduction in RIP3, the markers of necroptosis in striatum. In addition to the remarkable recovery of the striatal volume after engraftment, the motor activities were enhanced in the 3-NP + cell group compared to the 3-NP + vehicle group. Taken together, our results demonstrated the in vivo advantages of OE-MSCs treatment in an HD rat model with numerous positive paracrine effects including behavioral and anatomical recovery.

Neuroectodermal Stem Cells Grafted into the Injured Spinal Cord Induce Both Axonal Regeneration and Morphological Restoration via Multiple Mechanisms

Spinal cord contusion injury leads to severe loss of gray and white matter and subsequent deficit of motor and sensory functions below the lesion. In this study, we investigated whether application of murine clonal embryonic neuroectodermal stem cells can prevent the spinal cord secondary damage and induce functional recovery. Stem cells (NE-GFP-4C cell line) were grafted intraspinally or intravenously immediately or one week after thoracic spinal cord contusion injury. Control animals received cell culture medium or fibrin intraspinally one week after injury. Functional tests (Basso, Beattie, Bresnahan, CatWalk^®) and detailed morphological analysis were performed to evaluate the effects of grafted cells. Stem cells applied either locally or intravenously induced significantly improved functional recovery compared with their controls. Morphologically, stem cell grafting prevented the formation of secondary injury and promoted sparing of the gray and white matters. The transplanted cells integrated into the host tissue and differentiated into neurons, astrocytes, and oligodendrocytes. In intraspinally grafted animals, the corticospinal tract axons regenerated along the ventral border of the cavity and have grown several millimeters, even beyond the caudal end of the lesion. The extent of regeneration and functional improvement was inversely related to the amounts of chondroitin sulphate and ephrin-B2 molecules around the cavity and to the microglial and astrocytic reactions in the injured segment early after injury. The grafts produced glial cell derived neurotrophic factor, macrophage inflammatory protein-1a, interleukin (IL)-6 and IL-10 in a paracrine fashion for at least one week. Treating the grafted cords with neutralizing antibodies against these four factors through the use of osmotic pumps nearly completely abolished the effect of the graft. The non-significant functional improvement after function blocking is likely because the stem cell derivatives settled in the injured cord. These data suggest that grafted neuroectodermal stem cells are able to prevent the secondary spinal cord damage and induce significant regeneration via multiple mechanisms.