Murine neural crest stem cells and embryonic stem cell-derived neuron precursors survive and differentiate after transplantation in a model of dorsal root avulsion

Dorsal Root Injury-A Model for Exploring Pathophysiology and Therapeutic Strategies in Spinal Cord Injury

Unraveling the cellular and molecular mechanisms of spinal cord injury is fundamental for our possibility to develop successful therapeutic approaches. These approaches need to address the issues of the emergence of a non-permissive environment for axonal growth in the spinal cord, in combination with a failure of injured neurons to mount an effective regeneration program. Experimental in vivo models are of critical importance for exploring the potential clinical relevance of mechanistic findings and therapeutic innovations. However, the highly complex organization of the spinal cord, comprising multiple types of neurons, which form local neural networks, as well as short and long-ranging ascending or descending pathways, complicates detailed dissection of mechanistic processes, as well as identification/verification of therapeutic targets. Inducing different types of dorsal root injury at specific proximo-distal locations provide opportunities to distinguish key components underlying spinal cord regeneration failure. Crushing or cutting the dorsal root allows detailed analysis of the regeneration program of the sensory neurons, as well as of the glial response at the dorsal root-spinal cord interface without direct trauma to the spinal cord. At the same time, a lesion at this interface creates a localized injury of the spinal cord itself, but with an initial neuronal injury affecting only the axons of dorsal root ganglion neurons, and still a glial cell response closely resembling the one seen after direct spinal cord injury. In this review, we provide examples of previous research on dorsal root injury models and how these models can help future exploration of mechanisms and potential therapies for spinal cord injury repair.

Optimizing Olfactory Ensheathing Cell Transplantation for Spinal Cord Injury Repair

Cell transplantation constitutes an important avenue for development of new treatments for spinal cord injury (SCI). These therapies are aimed at supporting neural repair and/or replacing lost cells at the injury site. To date, various cell types have been trialed, with most studies focusing on different types of stem cells or glial cells. Here, we review commonly used cell transplantation approaches for spinal cord injury (SCI) repair, with focus on transplantation of olfactory ensheathing cells (OECs), the glial cells of the primary olfactory nervous system. OECs are promising candidates for promotion of neural repair given that they support continuous regeneration of the olfactory nerve that occurs throughout life. Further, OECs can be accessed from the nasal mucosa (olfactory neuroepithelium) at the roof of the nasal cavity and can be autologously transplanted. OEC transplantation has been trialed in many animal models of SCI, as well as in human clinical trials. While several studies have been promising, outcomes are variable and the method needs improvement to enhance aspects such as cell survival, integration, and migration. As a case study, we include the approaches used by our team (the Clem Jones Centre for Neurobiology and Stem Cell Research, Griffith University, Nathan, QLD, Australia) to address the current problems with OEC transplantation and discuss how the therapeutic potential of OEC transplantation can be improved. Our approach includes discovery research to improve our knowledge of OEC biology, identifying natural and synthetic compounds to stimulate the neural repair properties of OECs, and designing three-dimensional cell constructs to create stable and transplantable cell structures.

Boosting Magnetoelectric Effect in Polymer-Based Nanocomposites

Polymer-based magnetoelectric composite materials have attracted a lot of attention due to their high potential in various types of applications as magnetic field sensors, energy harvesting, and biomedical devices. Current researches are focused on the increase in the efficiency of magnetoelectric transformation. In this work, a new strategy of arrangement of clusters of magnetic nanoparticles by an external magnetic field in PVDF and PFVD-TrFE matrixes is proposed to increase the voltage coefficient (αME) of the magnetoelectric effect. Another strategy is the use of 3-component composites through the inclusion of piezoelectric BaTiO3 particles. Developed strategies allow us to increase the αME value from ~5 mV/cm·Oe for the composite of randomly distributed CoFe2O4 nanoparticles in PVDF matrix to ~18.5 mV/cm·Oe for a composite of magnetic particles in PVDF-TrFE matrix with 5%wt of piezoelectric particles. The applicability of such materials as bioactive surface is demonstrated on neural crest stem cell cultures.

Therapeutic effects of peripherally administrated neural crest stem cells on pain and spinal cord changes after sciatic nerve transection

BACKGROUND

Severe peripheral nerve injury significantly affects patients' quality of life and induces neuropathic pain. Neural crest stem cells (NCSCs) exhibit several attractive characteristics for cell-based therapies following peripheral nerve injury. Here, we investigate the therapeutic effect of NCSC therapy and associated changes in the spinal cord in a sciatic nerve transection (SNT) model.

METHODS

Complex sciatic nerve gap injuries in rats were repaired with cell-free and cell-laden nerve scaffolds for 12 weeks (scaffold and NCSC groups, respectively). Catwalk gait analysis was used to assess the motor function recovery. The mechanical withdrawal threshold and thermal withdrawal latency were used to assess the development of neuropathic pain. Activation of glial cells was examined by immunofluorescence analyses. Spinal levels of extracellular signal-regulated kinase (ERK), NF-κB P65, brain-derived neurotrophic factor (BDNF), growth-associated protein (GAP)-43, calcitonin gene-related peptide (CGRP), and inflammation factors were calculated by western blot analysis.

RESULTS

Catwalk gait analysis showed that animals in the NCSC group exhibited a higher stand index and Max intensity At (%) relative to those that received the cell-free scaffold (scaffold group) (p < 0.05). The mechanical and thermal allodynia in the medial-plantar surface of the ipsilateral hind paw were significantly relieved in the NCSC group. Sunitinib (SNT)-induced upregulation of glial fibrillary acidic protein (GFAP) (astrocyte) and ionized calcium-binding adaptor molecule 1 (Iba-1) (microglia) in the ipsilateral L4-5 dorsal and ventral horn relative to the contralateral side. Immunofluorescence analyses revealed decreased astrocyte and microglia activation. Activation of ERK and NF-κB signals and expression of transient receptor potential vanilloid 1 (TRPV1) expression were downregulated.

CONCLUSION

NCSC-laden nerve scaffolds mitigated SNT-induced neuropathic pain and improved motor function recovery after sciatic nerve repair. NCSCs also protected the spinal cord from SNT-induced glial activation and central sensitization.

Neural crest-like stem cells for tissue regeneration

Neural crest stem cells (NCSCs) are a transient population of cells that arise during early vertebrate development and harbor stem cell properties, such as self‐renewal and multipotency. These cells form at the interface of non‐neuronal ectoderm and neural tube and undergo extensive migration whereupon they contribute to a diverse array of cell and tissue derivatives, ranging from craniofacial tissues to cells of the peripheral nervous system. Neural crest‐like stem cells (NCLSCs) can be derived from pluripotent stem cells, placental tissues, adult tissues, and somatic cell reprogramming. NCLSCs have a differentiation capability similar to NCSCs, and possess great potential for regenerative medicine applications. In this review, we present recent developments on the various approaches to derive NCLSCs and the therapeutic application of these cells for tissue regeneration.

Ozone influences migration and proliferation of neural stem cells in vitro

Ozone (O₃) is a short-lived molecule which can be produced in a controlled reaction when oxygen is exposed to electric discharge. In the last few decades, many publications dealing both with animals and humans reported beneficial effects of ozone administration linked to its immunomodulatory and protective role against cellular damage. This is the first work which brings insight into how ozone influences cells of neural lineage in vitro and hypothesizes the potential molecular and novel electromagnetic mechanisms behind its action. By using neural stem cells, we show that ozone, especially in concentrations of around 11 μg/mL, significantly increases the speed of neural cell migration. With much lower effects, it also increases cell proliferation and cytokine production. Results of this study, at least partly, explain the observed beneficial effects of ozone in diseases of the nervous system tested on animal models and in human clinical trials. Therefore, here described effects of ozone on cellular level represent a firm basis for further investigation of possible applications of ozone in regeneration of the nervous system.

Non-thermal plasma-enhanced low-temperature catalytic desulfurization of electrolytic aluminum flue gas by CuO-ZrSnO4: experimental and numerical analysis

Catalytic desulfurization is favored for its ability to desulfurize low concentrations of SO₂ by generating sulfur without the need for flue gas conditioning or additives. Maintaining reaction efficiency at a low temperature would justify the industrial scale use of this method. To that end, in this study, we modified a previously reported highly efficient CuO-ZrSnO₄ catalyst and investigated its desulfurization performance. The non-thermal plasma (NTP) method was used to enhance the low-temperature efficiency of the catalyst. The desulfurization rate was significantly improved without generating excess heat or by-products in the low-output mode of post-plasma-catalysis-type (PPC-type) dielectric barrier discharge (DBD). In addition, we studied the physicochemical properties of the catalyst (pore structure, physical structure, morphology, electronic properties, and chemical state) under plasma enhancement conditions. The catalyst loaded with 20 wt% Cu and aged at 40 °C exhibited optimum desulfurization performance. This study provides a theoretical foundation for the analysis of plasma-enhanced catalytic desulfurization under low-temperature conditions. Graphical abstract.

Extracellular Vesicles as Innovative Tool for Diagnosis, Regeneration and Protection against Neurological Damage

Extracellular vesicles (EVs) have recently attracted a great deal of interest as they may represent a new biosignaling paradigm. According to the mode of biogenesis, size and composition, two broad categories of EVs have been described, exosomes and microvesicles. EVs have been shown to carry cargoes of signaling proteins, RNA species, DNA and lipids. Once released, their content is selectively taken up by near or distant target cells, influencing their behavior. Exosomes are involved in cell–cell communication in a wide range of embryonic developmental processes and in fetal–maternal communication. In the present review, an outline of the role of EVs in neural development, regeneration and diseases is presented. EVs can act as regulators of normal homeostasis, but they can also promote either neuroinflammation/degeneration or tissue repair in pathological conditions, depending on their content. Since EV molecular cargo constitutes a representation of the origin cell status, EVs can be exploited in the diagnosis of several diseases. Due to their capability to cross the blood–brain barrier (BBB), EVs not only have been suggested for the diagnosis of central nervous system disorders by means of minimally invasive procedures, i.e., “liquid biopsies”, but they are also considered attractive tools for targeted drug delivery across the BBB. From the therapeutic perspective, mesenchymal stem cells (MSCs) represent one of the most promising sources of EVs. In particular, the neuroprotective properties of MSCs derived from the dental pulp are here discussed.

How to face the aging world - lessons from dementia research

A continuous rise in life expectancy has led to an increase in the number of senior citizens, now amounting to a fifth of the global population, and to a dramatic increase in the prevalence of diseases of the elderly. This review discusses the threat of dementia, a disease that imposes enormous financial burden on health systems and warrants efficient therapeutic solutions. What we learned from numerous failed clinical trials is that we have to immediately take into account two major elements: early detection of dementia, much before the onset of symptoms, and personalized (precision) medicine treatment approach. We also discuss some of the most promising therapeutic directions, including stem cells, exosomes, electromagnetic fields, and ozone.

Recent Applications of Three Dimensional Printing in Cardiovascular Medicine

Three dimensional (3D) printing, which consists in the conversion of digital images into a 3D physical model, is a promising and versatile field that, over the last decade, has experienced a rapid development in medicine. Cardiovascular medicine, in particular, is one of the fastest growing area for medical 3D printing. In this review, we firstly describe the major steps and the most common technologies used in the 3D printing process, then we present current applications of 3D printing with relevance to the cardiovascular field. The technology is more frequently used for the creation of anatomical 3D models useful for teaching, training, and procedural planning of complex surgical cases, as well as for facilitating communication with patients and their families. However, the most attractive and novel application of 3D printing in the last years is bioprinting, which holds the great potential to solve the ever-increasing crisis of organ shortage. In this review, we then present some of the 3D bioprinting strategies used for fabricating fully functional cardiovascular tissues, including myocardium, heart tissue patches, and heart valves. The implications of 3D bioprinting in drug discovery, development, and delivery systems are also briefly discussed, in terms of in vitro cardiovascular drug toxicity. Finally, we describe some applications of 3D printing in the development and testing of cardiovascular medical devices, and the current regulatory frameworks that apply to manufacturing and commercialization of 3D printed products.

Overexpression of TG2 enhances the differentiation of ectomesenchymal stem cells into neuron‑like cells and promotes functional recovery in adult rats following spinal cord injury

Ectomesenchymal stem cells (EMSCs) represent a type of adult stem cells derived from the cranial neural crest. These cells are capable of self-renewal and have the potential for multidirectional differentiation. Tissue transglutaminase type 2 (TG2) is a ubiquitously expressed member of the transglutaminase family of Ca²⁺-dependent crosslinking enzymes. However, the effect of TG2 on neural differentiation and proliferation of EMSCs remains unknown. To determine whether TG2 improves EMSC proliferation and neurogenesis, a stable TG2-overexpressing EMSC cell line (TG2-EMSCs) was established by using an adenovirus system. Immunofluorescence staining and western blot analyses demonstrated that TG2 overexpression had beneficial effects on the rate of EMSC neurogenesis, and that the proliferative capacity of TG2-EMSCs was higher than that of controls. Furthermore, the results of western blotting revealed that extracellular matrix (ECM) and neurotrophic factors were upregulated during the differentiation of TG2-EMSCs. Notably, TG2-EMSC transplantation in an animal model of spinal cord injury (SCI), TG2-EMSCs differentiated into neuron-like cells and enhanced the repair of SCI. Taken together, these results demonstrated that TG2 gene transfection may offer a novel strategy to enhance EMSC proliferation and neurogenesis in vivo and in vitro, which may ultimately facilitate EMSC-based transplantation therapy in patients with SCI.

Neural crest stem cells protect spinal cord neurons from excitotoxic damage and inhibit glial activation by secretion of brain-derived neurotrophic factor

The acute phase of spinal cord injury is characterized by excitotoxic and inflammatory events that mediate extensive neuronal loss in the gray matter. Neural crest stem cells (NCSCs) can exert neuroprotective and anti-inflammatory effects that may be mediated by soluble factors. We therefore hypothesize that transplantation of NCSCs to acutely injured spinal cord slice cultures (SCSCs) can prevent neuronal loss after excitotoxic injury. NCSCs were applied onto SCSCs previously subjected to N-methyl-d-aspartate (NMDA)-induced injury. Immunohistochemistry and TUNEL staining were used to quantitatively study cell populations and apoptosis. Concentrations of neurotrophic factors were measured by ELISA. Migration and differentiation properties of NCSCs on SCSCs, laminin, or hyaluronic acid hydrogel were separately studied. NCSCs counteracted the loss of NeuN-positive neurons that was otherwise observed after NMDA-induced excitotoxicity, partly by inhibiting neuronal apoptosis. They also reduced activation of both microglial cells and astrocytes. The concentration of brain-derived neurotrophic factor (BDNF) was increased in supernatants from SCSCs cultured with NCSCs compared to SCSCs alone and BDNF alone mimicked the effects of NCSC application on SCSCs. NCSCs migrated superficially across the surface of SCSCs and showed no signs of neuronal or glial differentiation but preserved their expression of SOX2 and Krox20. In conclusion, NCSCs exert neuroprotective, anti-apoptotic and glia-inhibitory effects on excitotoxically injured spinal cord tissue, some of these effects mediated by secretion of BDNF. However, the investigated NCSCs seem not to undergo neuronal or glial differentiation in the short term since markers indicative of an undifferentiated state were expressed during the entire observation period.

Embryonic Stem Cells in Development and Regenerative Medicine

After progressive improvement in embryonic stem (ES) cell field, several studies have been conducted to explore the usage of ES cells in regenerative medicine. Unlimited self renewal and pluripoteny properties, combined with encouraging preclinical trials, remark that ES cell technology might be promising for clinical practice. ES cells, which can form three germ layers in vitro, are potential candidates to study development at the cellular and molecular level. Understanding the cell fate decision and differentiation processes during development might enable generating functional progenitor cells for tissue restoration. Progression in gene modifications and tissue engineering technology has facilitated the derivation of desired cells for therapy. Success in differentiation protocols and identification the regulatory pathways simplify the research for clinical applications. Although there are established protocols for cell differentiation in vitro and promising preclinical studies in vivo, many challenges need to be adressed before clinical translation. In this review, ES cells are discussed as a model of development in vitro and as a potential candidate for regenerative medicine. This review also dissusses current challenges for ES cell based therapy.

Boundary cap neural crest stem cell transplants contribute Mts1/S100A4-expressing cells in the glial scar

AIM

During development, boundary cap neural crest stem cells (bNCSCs) assist sensory axon growth into the spinal cord. Here we repositioned them to test if they assist regeneration of sensory axons in adult mice after dorsal root avulsion injury.

MATERIALS & METHODS

Avulsed mice received bNCSC or human neural progenitor (hNP) cell transplants and their contributions to glial scar formation and sensory axon regeneration were analyzed with immunohistochemistry and transganglionic tracing.

RESULTS

hNPs and bNCSCs form similar gaps in the glial scar, but unlike hNPs, bNCSCs contribute Mts1/S100A4 (calcium-binding protein) expression to the scar and do not assist sensory axon regeneration.

CONCLUSION

bNCSC transplants contribute nonpermissive Mts1/S100A4-expressing cells to the glial scar after dorsal root avulsion.

Efficient generation of functional Schwann cells from adipose-derived stem cells in defined conditions

Schwann cells (SCs) are hitherto regarded as the most promising candidates for viable cell-based therapy to peripheral nervous system (PNS) injuries or degenerative diseases. However, the extreme drawbacks of transplanting autologous SCs for clinical applications still represent a significant bottleneck in neural regenerative medicine, mainly owing to the need of sacrificing a functional nerve to generate autologous SCs and the nature of slow expansion of the SCs. Thus, it is of great importance to establish an alternative cell system for the generation of sufficient SCs. Here, we demonstrated that adipose-derived stem cells (ADSCs) of rat robustly give rise to morphological, phenotypic and functional SCs using an optimized protocol. After undergoing a 3-week in vitro differentiation, almost all of treated ADSCs exhibited spindle shaped morphology similar to genuine SCs and expressed SC markers GFAP and S100. Most importantly, apart from acquisition of SC antigenic and biochemical features, the ADSC-derived SCs were functionally identical to native SCs as they possess a potential ability to form myelin, and secret nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF) and glia-derived neurotrophic factor (GDNF). The current study may provide an ideal strategy for harvesting sufficient SCs for cell-based treatment of various peripheral nerve injuries or disorders.

Human Embryonic Stem Cell-Derived Progenitors Assist Functional Sensory Axon Regeneration after Dorsal Root Avulsion Injury

Dorsal root avulsion results in permanent impairment of sensory functions due to disconnection between the peripheral and central nervous system. Improved strategies are therefore needed to reconnect injured sensory neurons with their spinal cord targets in order to achieve functional repair after brachial and lumbosacral plexus avulsion injuries. Here, we show that sensory functions can be restored in the adult mouse if avulsed sensory fibers are bridged with the spinal cord by human neural progenitor (hNP) transplants. Responses to peripheral mechanical sensory stimulation were significantly improved in transplanted animals. Transganglionic tracing showed host sensory axons only in the spinal cord dorsal horn of treated animals. Immunohistochemical analysis confirmed that sensory fibers had grown through the bridge and showed robust survival and differentiation of the transplants. Section of the repaired dorsal roots distal to the transplant completely abolished the behavioral improvement. This demonstrates that hNP transplants promote recovery of sensorimotor functions after dorsal root avulsion, and that these effects are mediated by spinal ingrowth of host sensory axons. These results provide a rationale for the development of novel stem cell-based strategies for functionally useful bridging of the peripheral and central nervous system.

Neural crest cell evolution: how and when did a neural crest cell become a neural crest cell

As vertebrates evolved from protochordates, they shifted to a more predatory lifestyle, and radiated and adapted to most niches of the planet. This process was largely facilitated by the generation of novel vertebrate head structures, which were derived from neural crest cells (NCC). The neural crest is a unique vertebrate cell population that is frequently termed the "fourth germ layer" because it forms in conjunction with the other germ layers and contributes to a diverse array of cell types and tissues including the craniofacial skeleton, the peripheral nervous system, and pigment cells among many other tissues and cell types. NCC are defined by their origin at the neural plate border, via an epithelial-to-mesenchymal transition (EMT), together with multipotency and polarized patterns of migration. These defining characteristics, which evolved independently in the germ layers of invertebrates, were subsequently co-opted through their gene regulatory networks to form NCC in vertebrates. Moreover, recent data suggest that the ability to undergo an EMT was one of the latter features co-opted by NCC. In this review, we discuss the potential origins of NCC and how they evolved to contribute to nearly all tissues and organs throughout the body, based on paleontological evidence together with an evaluation of the evolution of molecules involved in NCC development and their migratory cell paths.