Oligodendrocytes engineered with migratory proteins as effective graft source for cell transplantation in multiple sclerosis

New insights into the roles of oligodendrocytes regulation in ischemic stroke recovery

Oligodendrocytes (OLs), the myelin-forming cells of the central nervous system, are integral to axonal integrity and function. Hypoxia-ischemia episodes can cause severe damage to these vulnerable cells through excitotoxicity, oxidative stress, inflammation, and mitochondrial dysfunction, leading to axonal dystrophy, neuronal dysfunction, and neurological impairments. OLs damage can result in demyelination and myelination disorders, severely impacting axonal function, structure, metabolism, and survival. Adult-onset stroke, periventricular leukomalacia, and post-stroke cognitive impairment primarily target OLs, making them a critical therapeutic target. Therapeutic strategies targeting OLs, myelin, and their receptors should be given more emphasis to attenuate ischemia injury and establish functional recovery after stroke. This review summarizes recent advances on the function of OLs in ischemic injury, as well as the present and emerging principles that serve as the foundation for protective strategies against OL deaths.

Stem Cells Attenuate the Inflammation Crosstalk Between Ischemic Stroke and Multiple Sclerosis: A Review

The immense neuroinflammation induced by multiple sclerosis (MS) promotes a favorable environment for ischemic stroke (IS) development, making IS a deadly complication of MS. The overlapping inflammation in MS and IS is a prelude to the vascular pathology, and an inherent cell death mechanism that exacerbates neurovascular unit (NVU) impairment in the disease progression. Despite this consequence, no therapies focus on reducing IS incidence in patients with MS. To this end, the preclinical and clinical evidence we review here argues for cell-based regenerative medicine that will augment the NVU dysfunction and inflammation to ameliorate IS risk.

An update on intracerebral stem cell grafts

INTRODUCTION

Primary neurological disorders are notoriously debilitating and deadly, and over the past four decades stem cell therapy has emerged as a promising treatment. Translation of stem cell therapies from the bench to the clinic requires a better understanding of delivery protocols, safety profile, and efficacy in each disease. Areas covered: In this review, benefits and risks of intracerebral stem cell transplantation are presented for consideration. Milestone discoveries in stem cell applications are reviewed to examine the efficacy and safety of intracerebral stem cell transplant therapy for disorders of the central nervous system and inform design of translatable protocols for clinically feasible stem cell-based treatments. Expert commentary: Intracerebral administration, compared to peripheral delivery, is more invasive and carries the risk of open brain surgery. However, direct cell implantation bypasses the blood-brain barrier and reduces the first-pass effect, effectively increasing the therapeutic cell deposition at its intended site of action. These benefits must be weighed with the risk of graft-versus-host immune response. Rigorous clinical trials are underway to assess the safety and efficacy of intracerebral transplants, and if successful will lead to widely available stem cell therapies for neurologic diseases in the coming years.

Molecular Mechanisms of Oligodendrocyte Regeneration in White Matter-Related Diseases

Even in adult brains, restorative mechanisms are still retained to maintain the microenvironment. Under the pathological conditions of central nervous system (CNS) diseases, several immature cells in the brain would be activated as a compensative response. As the concept of the neurovascular unit emphasizes, cell-cell interactions play important roles in this restorative process. White matter damage and oligodendrocyte loss are representative characteristics for many neurodegenerative diseases. In response to oligodendrocyte damage, residual oligodendrocyte precursor cells (OPCs) initiate their proliferation and differentiation for the purpose of remyelination. Although mechanisms of oligodendrogenesis and remyelination in CNS diseases are still mostly unknown and understudied, accumulated evidence now suggests that support from neighboring cells is necessary for OPC proliferation and differentiation. In this review, we first overview basic mechanisms of interaction between oligodendrocyte lineage cells and neighboring cells, and then introduce how oligodendrogenesis occurs under the conditions of neurodegenerative diseases, focusing on vascular cognitive impairment syndrome, Alzheimer’s disease, and multiple sclerosis.

Directed Differentiation of Oligodendrocyte Progenitor Cells From Mouse Induced Pluripotent Stem Cells

Several neurological disorders, such as multiple sclerosis, the leukodystrophies, and traumatic injury, result in loss of myelin in the central nervous system (CNS). These disorders may benefit from cell-based therapies that prevent further demyelination or are able to restore lost myelin. One potential therapeutic strategy for these disorders is the manufacture of oligodendrocyte progenitor cells (OPCs) by the directed differentiation of pluripotent stem cells, including induced pluripotent stem cells (iPSCs). It has been proposed that OPCs could be transplanted into demyelinated or dysmyelinated regions of the CNS, where they would migrate to the area of injury before terminally differentiating into myelinating oligodendrocytes. OPCs derived from mouse iPSCs are particularly useful for modeling this therapeutic approach and for studying the biology of oligodendrocyte progenitors because of the availability of mouse models of neurological disorders associated with myelin deficiency. Moreover, the utility of miPSC-derived OPCs would be significantly enhanced by the adoption of a consistent, reproducible differentiation protocol that allows OPCs derived from different cell lines to be robustly characterized and compared. Here we describe a standardized, defined protocol that reliably directs the differentiation of miPSCs to generate high yields of OPCs that are capable of maturing into oligodendrocytes.

Developments in intracerebral stem cell grafts

The field of stem cell therapy has emerged as a promising research area for brain repair. Optimizing the safety and efficacy of the therapy for clinical trials will require revisiting transplantation protocols. The cell delivery route stands as a key translational item that warrants careful consideration in facilitating the success of stem cell therapy in the clinic. Intracerebral administration, compared to peripheral route, requires an invasive procedure to directly implant stem cells into injured brain. Although invasive, intracerebral transplantation circumvents the prohibitive blood brain barrier in allowing grafted cells when delivered peripherally to penetrate the brain and reach the discreet damaged brain tissues. This review will highlight milestone discoveries in cell therapy for neurological disorders, with emphasis on intracerebral transplantation in relevant animal models and provide insights necessary to optimize the safety and efficacy of cell therapy for the treatment of Parkinson's disease, Huntington's disease, stroke and traumatic brain injury.

Redox regulation of cytoskeletal dynamics during differentiation and de-differentiation

BACKGROUND

The cytoskeleton, unlike the bony vertebrate skeleton or the exoskeleton of invertebrates, is a highly dynamic meshwork of protein filaments that spans through the cytosol of eukaryotic cells. Especially actin filaments and microtubuli do not only provide structure and points of attachments, but they also shape cells, they are the basis for intracellular transport and distribution, all types of cell movement, and--through specific junctions and points of adhesion--join cells together to form tissues, organs, and organisms.

SCOPE OF REVIEW

The fine tuned regulation of cytoskeletal dynamics is thus indispensible for cell differentiation and all developmental processes. Here, we discussed redox signalling mechanisms that control this dynamic remodeling. Foremost, we emphasised recent discoveries that demonstrated reversible thiol and methionyl switches in the regulation of actin dynamics.

MAJOR CONCLUSIONS

Thiol and methionyl switches play an essential role in the regulation of cytoskeletal dynamics.

GENERAL SIGNIFICANCE

The dynamic remodeling of the cytoskeleton is controlled by various redox switches. These mechanisms are indispensible during development and organogenesis and might contribute to numerous pathological conditions. This article is part of a Special Issue entitled Redox regulation of differentiation and de-differentiation.