Autologous mesenchymal bone marrow stem cells: practical considerations

Human olfactory mesenchymal stromal cell transplantation ameliorates experimental autoimmune encephalomyelitis revealing an inhibitory role for IL16 on myelination

One of the therapeutic approaches for the treatment of the autoimmune demyelinating disease, multiple sclerosis (MS) is bone marrow mesenchymal stromal cell (hBM-MSCs) transplantation. However, given their capacity to enhance myelination in vitro, we hypothesised that human olfactory mucosa-derived MSCs (hOM-MSCs) may possess additional properties suitable for CNS repair. Herein, we have examined the efficacy of hOM-MSCs versus hBM-MSCs using the experimental autoimmune encephalomyelitis (EAE) model. Both MSC types ameliorated disease, if delivered during the initial onset of symptomatic disease. Yet, only hOM-MSCs improved disease outcome if administered during established disease when animals had severe neurological deficits. Histological analysis of spinal cord lesions revealed hOM-MSC transplantation reduced blood–brain barrier disruption and inflammatory cell recruitment and enhanced axonal survival. At early time points post-hOM-MSC treatment, animals had reduced levels of circulating IL-16, which was reflected in both the ability of immune cells to secrete IL-16 and the level of IL-16 in spinal cord inflammatory lesions. Further in vitro investigation revealed an inhibitory role for IL-16 on oligodendrocyte differentiation and myelination. Moreover, the availability of bioactive IL-16 after demyelination was reduced in the presence of hOM-MSCs. Combined, our data suggests that human hOM-MSCs may have therapeutic benefit in the treatment of MS via an IL-16-mediated pathway, especially if administered during active demyelination and inflammation.

Cell Therapy for Multiple Sclerosis

Cell therapy is considered a promising potential treatment for multiple sclerosis, perhaps particularly for the progressive form of the disease for which there are currently no useful treatments. Over the past two decades or more, much progress has been made in understanding the biology of MS and in the experimental development of cell therapy for this disease. Three quite distinct forms of cell therapy are currently being pursued. The first seeks to use stem cells to replace damaged myelin-forming oligodendrocytes within the CNS; the second aims, in effect, to replace the individual's misfunctioning immune system, making use of haematopoietic stem cells; and the third seeks to utilise endogenous stem cell populations by mobilisation with or without in vitro expansion, exploiting their various reparative and neuroprotective properties. In this article we review progress in these three separate areas, summarising the experimental background and clinical progress thus far made.

Bone marrow mesenchymal stem cells for treatment of pancreatic diseases: Research status and prospects

The incidence of pancreatic diseases is increasing year by year. Current treatments for pancreatic diseases are mainly symptomatic, and the research on the repair and restoration of function of the pancreatic cells progresses slowly. Stem cells have been widely used in the treatment of diseases in recent years because of their ability of multi-directional differentiation and repair of cell damage caused by disease and injury. Numerous studies confirm that pancreatic stem cells after transplantation can differentiate into pancreatic cells and play an important role in the recovery of external secretory function and repair of the damaged pancreatic cells. Particularly, both in vivo and in vitro studies show that bone marrow mesenchymal stem cells have achieved remarkable results in the treatment of pancreatic diseases, laying a theoretical and practical basis for clinical treatment of pancreatic diseases with stem cells. This article outlines the progress in treatment of acute pancreatitis, chronic pancreatitis and pancreatic cancer with bone marrow mesenchymal stem cells, demonstrating that stem cells are expected to become one of new methods for the treatment of pancreatic diseases.

Restrained Th17 response and myeloid cell infiltration into the central nervous system by human decidua-derived mesenchymal stem cells during experimental autoimmune encephalomyelitis

BACKGROUND

Multiple sclerosis is a widespread inflammatory demyelinating disease. Several immunomodulatory therapies are available, including interferon-β, glatiramer acetate, natalizumab, fingolimod, and mitoxantrone. Although useful to delay disease progression, they do not provide a definitive cure and are associated with some undesirable side-effects. Accordingly, the search for new therapeutic methods constitutes an active investigation field. The use of mesenchymal stem cells (MSCs) to modify the disease course is currently the subject of intense interest. Decidua-derived MSCs (DMSCs) are a cell population obtained from human placental extraembryonic membranes able to differentiate into the three germ layers. This study explores the therapeutic potential of DMSCs.

METHODS

We used the experimental autoimmune encephalomyelitis (EAE) animal model to evaluate the effect of DMSCs on clinical signs of the disease and on the presence of inflammatory infiltrates in the central nervous system. We also compared the inflammatory profile of spleen T cells from DMSC-treated mice with that of EAE control animals, and the influence of DMSCs on the in vitro definition of the Th17 phenotype. Furthermore, we analyzed the effects on the presence of some critical cell types in central nervous system infiltrates.

RESULTS

Preventive intraperitoneal injection of DMSCs resulted in a significant delay of external signs of EAE. In addition, treatment of animals already presenting with moderate symptoms resulted in mild EAE with reduced disease scores. Besides decreased inflammatory infiltration, diminished percentages of CD4(+)IL17(+), CD11b(+)Ly6G(+) and CD11b(+)Ly6C(+) cells were found in infiltrates of treated animals. Early immune response was mitigated, with spleen cells of DMSC-treated mice displaying low proliferative response to antigen, decreased production of interleukin (IL)-17, and increased production of the anti-inflammatory cytokines IL-4 and IL-10. Moreover, lower RORγT and higher GATA-3 expression levels were detected in DMSC-treated mice. DMSCs also showed a detrimental influence on the in vitro definition of the Th17 phenotype.

CONCLUSIONS

DMSCs modulated the clinical course of EAE, modified the frequency and cell composition of the central nervous system infiltrates during the disease, and mediated an impairment of Th17 phenotype establishment in favor of the Th2 subtype. These results suggest that DMSCs might provide a new cell-based therapy for the control of multiple sclerosis.

Autografting of bone marrow mesenchymal stem cells alleviates streptozotocin‑induced diabetes in miniature pigs: real-time tracing with MRI in vivo

Cellular replacement therapy for diabetes mellitus (DM) has received much attention. In this study, we investigated the effect of transplantation of autologous bone marrow-derived mesenchymal stem cells (ABMSCs) in streptozotocin (STZ)-induced diabetic miniature pigs. Miniature pig BMSCs were cultured, labeled with superparamagnetic iron oxide (SPIO) and transplanted into the pancreas of diabetic miniature pigs through targeted intervention. Blood glucose levels, intravenous and oral glucose tolerance test (OGTT), serum insulin, C-peptide and islets histology were analyzed. These transplanted cells were then identified by magnetic resonance imaging (MRI). The results showed that transplantation of ABMSCs reversed STZ-induced diabetes in miniature pigs. Blood glucose levels, intravenous, OGTT, serum insulin and C-peptide were significantly recovered in the diabetic minipigs with the autologous BMSC (DMAB) transplantation group. In addition, the number of islets was significantly increased in this group compared to the diabetic minipig control (DMC) group with conventional therapy. These data suggested the implantation of autologous BMSCs for type 1 diabetes treatment can partially restore the function of islet β cells and maintain blood glucose homeostasis. Transplanted autologous BMSCs may improve islet repairing by differentiating for new islets and change pancreatic microcirculation and be identified in a real-time manner using MRI in vivo.

Mesenchymal stem cell transplantation in multiple sclerosis

Mesenchymal stem cells (MSCs) are pluripotent non-hematopoietic precursor cells that can be isolated from bone marrow and numerous other tissues, culture-expanded to purity, and induced to differentiate in vitro and in vivo into mesodermal derivatives. MSCs exhibit many phenotypic and functional similarities to pericytes. The immunomodulatory, tissue protective, and repair-promoting properties of MSCs demonstrated both in vitro and in animal models make them an attractive potential therapy for MS and other conditions characterized by inflammation and/or tissue injury. Other potential advantages of MSCs as a therapeutic include the relative ease of culture expansion, relative immunoprivilege allowing allogeneic transplantation, and their ability to traffic from blood to areas of tissue allowing intravascular administration. The overall published experience with MSC transplantation in MS is modest, but several small case series and preliminary studies yielded promising results. Several groups, including us, recently initiated formal studies of autologous, culture-expanded, bone marrow-derived MSC transplantation in MS. Although there are several potential safety concerns, to date, the procedure has been well tolerated. Future studies that more definitively assess efficacy also will need to address several technical issues.

Translational research and therapeutic applications of stem cell transplantation in periodontal regenerative medicine

Stem cells have received a great deal of interest from the research community as potential therapeutic "tools" for a variety of chronic debilitating diseases that lack clinically effective therapies. Stem cells are also of interest for the regeneration of tooth-supporting tissues that have been lost to periodontal disease. Indeed, substantial data have demonstrated that the exogenous administration of stem cells or their derivatives in preclinical animal models of periodontal defects can restore damaged tissues to their original form and function. As we discuss here, however, considerable hurdles must be overcome before these findings can be responsibly translated to novel clinical therapies. Generally, the application of stem cells for periodontal therapy in clinics will not be realized until the best cell(s) to use, the optimal dose, and an effective mode of administration are identified. In particular, we need to better understand the mechanisms of action of stem cells after transplantation in the periodontium and to learn how to preciously control stem cell fates in the pathological environment around a tooth. From a translational perspective, we outline the challenges that may vary across preclinical models for the evaluation of stem cell therapy in situations that require periodontal reconstruction and the safety issues that are related to clinical applications of human stem cells. Although clinical trials that use autologous periodontal ligament stem cells have been approved and have already been initiated, proper consideration of the technical, safety, and regulatory concerns may facilitate, rather than inhibit, the clinical translation of new therapies.

The potential of mesenchymal stromal cells as a novel cellular therapy for multiple sclerosis

Multiple sclerosis (MS) is an inflammatory neurodegenerative disease of the CNS for which only partially effective therapies exist. Intense research defining the underlying immune pathophysiology is advancing both the understanding of MS as well as revealing potential targets for disease intervention. Mesenchymal stromal cell (MSC) therapy has the potential to modulate aberrant immune responses causing demyelination and axonal injury associated with MS, as well as to repair and restore damaged CNS tissue and cells. This article reviews the pathophysiology underlying MS, as well as providing a cutting-edge perspective into the field of MSC therapy based upon the experience of authors intrinsically involved in MS and MSC basic and translational science research.

Endothelial progenitor cell cotransplantation enhances islet engraftment by rapid revascularization

Impaired revascularization of transplanted islets is a critical problem that leads to progressive islet loss. Since endothelial progenitor cells (EPCs) are known to aid neovascularization, we aimed to enhance islet engraftment by cotransplanting EPCs with islets. Porcine islets, with (islet-EPC group) or without (islet-only group) human cord blood-derived EPCs, were transplanted into diabetic nude mice. The islet-EPC group reached euglycemia by ∼11 days posttransplantation, whereas the islet-only group did not. Also, the islet-EPC group had a higher serum porcine insulin level than the islet-only group. Islets from the islet-EPC group were more rapidly revascularized at the early period of transplantation without increment of final capillary density at the fully revascularized graft. Enhanced revascularization rate in the islet-EPC group was mainly attributed to stimulating vascular endothelial growth factor-A production from the graft. The rapid revascularization by EPC cotransplantation led to better graft perfusion and recovery from hypoxia. EPC cotransplantation was also associated with greater β-cell proliferation, probably by more basement membrane production and hepatocyte growth factor secretion. In conclusion, cotransplantation of EPCs and islets induces better islet engraftment by enhancing the rate of graft revascularization. These findings might provide a directly applicable tool to enhance the efficacy of islet transplantation in clinical practice.

Fusion between human mesenchymal stem cells and rodent cerebellar Purkinje cells

AIMS

we explored whether cellular fusion and heterokaryon formation between human and rodent cells in the cerebellum of mice occurs after intravenous injection of human bone marrow-derived mesenchymal stem cells (MSCs). The influence of central nervous system inflammation on this process was also assessed. In addition, we examined whether tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma, factors associated with inflammation, increase cellular fusion between human MSCs and rodent cerebellar neurons in vitro.

METHODS AND RESULTS

human MSCs were intravenously injected into mice with experimental autoimmune encephalomyelitis (EAE) and control mice. After 22 days, mouse Purkinje cells expressing human Golgi Zone were found within the Purkinje cell layer of the cerebellum, indicating that fusion and heterokaryon formation had occurred. The numbers of heterokaryons in the cerebellum were markedly increased in mice with EAE compared with control mice. Rodent cerebellar neuronal cells labelled with enhanced green fluorescent proteinin vitro were co-cultured with human bone marrow-derived MSCs in the presence of TNF-alpha and/or IFN-gamma to determine their influence on fusion events. We found that fusion between MSCs and cerebellar neurons did occur in vitro and that the frequency of cellular fusion increased in the presence of TNF-alpha and/or IFN-gamma.

CONCLUSIONS

we believe that this is the first paper to define fusion and heterokaryon formation between human MSCs and rodent cerebellar neurons in vivo. We have also demonstrated that fusion between these cell populations occurs in vitro. These findings indicate that MSCs may be potential therapeutic agents for cerebellar diseases, and other neuroinflammatory and neurodegenerative disorders.

Intravenous administration of auto serum-expanded autologous mesenchymal stem cells in stroke

Transplantation of human mesenchymal stem cells has been shown to reduce infarct size and improve functional outcome in animal models of stroke. Here, we report a study designed to assess feasibility and safety of transplantation of autologous human mesenchymal stem cells expanded in autologous human serum in stroke patients. We report an unblinded study on 12 patients with ischaemic grey matter, white matter and mixed lesions, in contrast to a prior study on autologous mesenchymal stem cells expanded in foetal calf serum that focused on grey matter lesions. Cells cultured in human serum expanded more rapidly than in foetal calf serum, reducing cell preparation time and risk of transmissible disorders such as bovine spongiform encephalomyelitis. Autologous mesenchymal stem cells were delivered intravenously 36-133 days post-stroke. All patients had magnetic resonance angiography to identify vascular lesions, and magnetic resonance imaging prior to cell infusion and at intervals up to 1 year after. Magnetic resonance perfusion-imaging and 3D-tractography were carried out in some patients. Neurological status was scored using the National Institutes of Health Stroke Scale and modified Rankin scores. We did not observe any central nervous system tumours, abnormal cell growths or neurological deterioration, and there was no evidence for venous thromboembolism, systemic malignancy or systemic infection in any of the patients following stem cell infusion. The median daily rate of National Institutes of Health Stroke Scale change was 0.36 during the first week post-infusion, compared with a median daily rate of change of 0.04 from the first day of testing to immediately before infusion. Daily rates of change in National Institutes of Health Stroke Scale scores during longer post-infusion intervals that more closely matched the interval between initial scoring and cell infusion also showed an increase following cell infusion. Mean lesion volume as assessed by magnetic resonance imaging was reduced by >20% at 1 week post-cell infusion. While we would emphasize that the current study was unblinded, did not assess overall function or relative functional importance of different types of deficits, and does not exclude placebo effects or a contribution of recovery as a result of the natural history of stroke, our observations provide evidence supporting the feasibility and safety of delivery of a relatively large dose of autologous mesenchymal human stem cells, cultured in autologous human serum, into human subjects with stroke and support the need for additional blinded, placebo-controlled studies on autologous mesenchymal human stem cell infusion in stroke.

Mechanisms of oxidative damage in multiple sclerosis and a cell therapy approach to treatment

Although significant advances have recently been made in the understanding and treatment of multiple sclerosis, reduction of long-term disability remains a key goal. Evidence suggests that inflammation and oxidative stress within the central nervous system are major causes of ongoing tissue damage in the disease. Invading inflammatory cells, as well as resident central nervous system cells, release a number of reactive oxygen and nitrogen species which cause demyelination and axonal destruction, the pathological hallmarks of multiple sclerosis. Reduction in oxidative damage is an important therapeutic strategy to slow or halt disease processes. Many drugs in clinical practice or currently in trial target this mechanism. Cell-based therapies offer an alternative source of antioxidant capability. Classically thought of as being important for myelin or cell replacement in multiple sclerosis, stem cells may, however, have a more important role as providers of supporting factors or direct attenuators of the disease. In this paper we focus on the antioxidant properties of mesenchymal stem cells and discuss their potential importance as a cell-based therapy for multiple sclerosis.

Bone marrow mesenchymal stem cell transplantation in patients with multiple sclerosis: a pilot study

We explore the safety, and therapeutic benefit of intrathecal injection of ex-vivo expanded autologous bone marrow derived mesenchymal stem cells (BM-MSCs) in 10 patients with advanced multiple sclerosis (MS). Patients were assessed at 3, 6 and 12 months. Assessment at 3-6 months revealed Expanded Disability Scale Score (EDSS) improvement in 5/7, stabilization in 1/7, and worsening in 1/7 patients. MRI at 3 months revealed new or enlarging lesions in 5/7 and Gadolinium (Gd+) enhancing lesions in 3/7 patients. Vision and low contrast sensitivity testing at 3 months showed improvement in 5/6 and worsening in 1/6 patients. Early results show hints of clinical but not radiological efficacy and evidence of safety with no serious adverse events.

Stem cells in genetic myelin disorders

The genetic myelin disorders are a range of diseases that manifest with severe neurological problems, often from infancy. It has been postulated for some time that stem cells might be an effective treatment for these disorders, primarily as agents to restore dysfunctional or lost myelin. Stem cells, however, may offer a wider range of therapeutic potential, for instance as vehicles to replace abnormal enzymes or genes, or to provide trophic support for residual CNS tissue. This article will review several of the more common genetic myelin disorders and currently available therapies, including bone marrow transplantation for adrenoleukodystrophy. Specific stem cell subtypes and their relevance to potential therapeutic use will be discussed and stem cell transplantation in animal model studies will also be reviewed.

The therapeutic potential of mesenchymal stem cell transplantation as a treatment for multiple sclerosis: consensus report of the International MSCT Study Group

Current therapies for multiple sclerosis effectively reduce inflammation, but do little in terms of repair to the damaged central nervous system. Cell-based therapies may provide a new strategy for bolstering regeneration and repair through neuro-axonal protection or remyelination. Mesenchymal stem cells modulate pathological responses in experimental autoimmune encephalitis, alleviating disease, but also stimulate repair of the central nervous system through the release of soluble factors. Autologous and allogeneic mesenchymal stem cells have been safely administered to individuals with hemato-oncological diseases and in a limited number of patients with multiple sclerosis. It is therefore reasonable to move mesenchymal stem cells transplantation into properly controlled human studies to explore their potential as a treatment for multiple sclerosis. Since it is likely that the first such studies will probably involve only small numbers of patients in a few centers, we formed an international panel comprising multiple sclerosis neurology and stem cell experts, as well as immunologists. The aims were to derive a consensus on the utilization of mesenchymal stem cells for the treatment of multiple sclerosis, along with protocols for the culture of the cells and the treatment of patients. This article reviews the consensus derived from our group on the rationale for mesenchymal stem cell transplantation, the methodology for generating mesenchymal stem cells and the first treatment protocol for multiple sclerosis patients.

Protective effects of neurotrophic factor-secreting cells in a 6-OHDA rat model of Parkinson disease

Stem cell-based therapy is a promising treatment for neurodegenerative diseases. In our laboratory, a novel protocol has been developed to induce bone marrow-derived mesenchymal stem cells (MSC) into neurotrophic factors- secreting cells (NTF-SC), thus combining stem cell-based therapy with the NTF-based neuroprotection. These cells produce and secrete factors such as brain-derived neurotrophic factor (BDNF) and glial cell-derived neurotrophic factor. Conditioned medium of the NTF-SC that was applied to a neuroblastoma cell line (SH-SY5Y) 1 h before exposure to the neurotoxin 6-hydroxydopamine (6-OHDA) demonstrated marked protection. An efficacy study was conducted on the 6-OHDA-induced lesion, a rat model of Parkinson's disease. The cells, either MSC or NTF-SC, were transplanted on the day of 6-OHDA administration and amphetamine-induced rotations were measured as a primary behavior index. We demonstrated that when transplanted posterior to the 6-OHDA lesion, the NTF-SC ameliorated amphetamine-induced rotations by 45%. HPLC analysis demonstrated that 6-OHDA induced dopamine depletion to a level of 21% compared to the untreated striatum. NTF-SC inhibited dopamine depletion to a level of 72% of the contralateral striatum. Moreover, an MRI study conducted with iron-labeled cells, followed by histological verification, revealed that the engrafted cells migrated toward the lesion. In a histological assessment, we found that the cells induced regeneration in the damaged striatal dopaminergic nerve terminal network. We therefore conclude that the induced MSC have a therapeutic potential for neurodegenerative processes and diseases, both by the NTFs secretion and by the migratory trait toward the diseased tissue.

Embryonic stem cell-derived cardiomyocytes as a model to study fetal arrhythmia related to maternal disease

Embryonic stem cell-derived cardiomyocytes (ESC-CM) have many of the phenotypic properties of authentic cardiomyocytes, and great interest has been shown in their possibilities for modelling human disease. Obstetric cholestasis affects 1 in 200 pregnant women in the United Kingdom. It is characterized by raised serum bile acids and complicated by premature delivery and unexplained fetal death at late gestation. It has been suggested that the fetal death is caused by the enhanced arrhythmogenic effect of bile acids in the fetal heart, and shown that neonatal susceptibility to bile acid-induced arrhythmia is lost in the adult rat cardiomyocyte. However, the mechanisms of the observed bile acid effects are not fully understood and their in vivo study in human beings is difficult. Here we use ESC-CM from both human and mouse ESCs to test our proposal that immature cardiomyocytes are more susceptible to the effect of raised bile acids than mature ones. We show that early ESC-CM exhibit bile acid-induced disruption of rhythm, depression of contraction and desynchronization of cell coupling. In both species the ESC-CM become resistant to these arrhythmias as the cells mature, and this develops in line with the respective gestational periods of mouse and human. This represents the first demonstration of the use of ESC-CM as a model system for human cardiac pathology, and opens the way for both investigation of mechanisms and a high throughput screen for drug discovery.

Adult stem cells for the treatment of neurological disease

The characteristic CNS responses to injury including increased cell production and attempts at regenerative repair - implicitly predicted where not directly demonstrated by Cajal, but only now more fully confirmed - have important implications for regenerative therapies. Spontaneous CNS cell replacement compares poorly with the regenerative functional repair seen elsewhere, but harnessing, stimulating or supplementing this process represents a new and attractive therapeutic concept.Stem cells, traditionally defined as clone-forming, self-renewing, pluripotent progenitor cells, have already proved themselves to be an invaluable source of transplantation material in several clinical settings, most notably haematological malignancy, and attention is now turning to a wider variety of diseases in which there may be potential for therapeutic intervention with stem cell transplantation. Neurological diseases, with their reputation for relentless progression and incurability are particularly tantalising targets. The optimal source of stem cells remains to be determined but bone marrow stem cells may themselves be included amongst the contenders.Any development of therapies using stem cells must depend on an underlying knowledge of their basic biology. The haemopoietic system has long been known to maintain circulating populations of cells with short life spans, and this system has greatly informed our knowledge of stem cell biology. In particular, it has helped yield the traditional stem cell model - a hierarchical paradigm of progressive lineage restriction. As cells differentiate, their fate choices become progressively more limited, and their capacity for proliferation reduced, until fully differentiated, mitotically quiescent cells are generated. Even this, however, is now under challenge.

Protecting axons in multiple sclerosis

Typically patients with multiple sclerosis (MS) experience acute episodes of neurological dysfunction, which recover followed, at a later stage, by slow and insidious accumulation of disability (disease progression). Disease progression reflects axon damage and loss within the central nervous system. However, the precise mechanism of axon injury in MS is not clear. Inflammation occurring during acute relapses undoubtedly causes some degree of acute axon damage, but epidemiological data and treatment studies have suggested that inflammation alone is not the sole cause of axonopathy. Indeed, there appears to be dissociation between inflammation and disease progression once a certain level of clinical disability has been reached because immune suppression in patients who have established disease progression does not halt the slow decrease of function. The slow and insidious loss of neurological function that occurs during the progressive phase of the disease implies a degenerative process. Whether axon drop-out occurs at these later stages because of previous inflammatory damage to axons; because of low grade inflammation causing damage to already vulnerable demyelinated axons; because of loss of trophic environment for axons to survive; or as part of a completely independent neurodegenerative process is not clear. Understanding disease mechanisms involved in the axonopathy of MS allows for the development of rational therapies for disease progression.

Glial precursor cell transplantation therapy for neurotrauma and multiple sclerosis

Traumatic injury to the brain or spinal cord and multiple sclerosis (MS) share a common pathophysiology with regard to axonal demyelination. Despite advances in central nervous system (CNS) repair in experimental animal models, adequate functional recovery has yet to be achieved in patients in response to any of the current strategies. Functional recovery is dependent, in large part, upon remyelination of spared or regenerating axons. The mammalian CNS maintains an endogenous reservoir of glial precursor cells (GPCs), capable of generating new oligodendrocytes and astrocytes. These GPCs are upregulated following traumatic or demyelinating lesions, followed by their differentiation into oligodendrocytes. However, this innate response does not adequately promote remyelination. As a result, researchers have been focusing their efforts on harvesting, culturing, characterizing, and transplanting GPCs into injured regions of the adult mammalian CNS in a variety of animal models of CNS trauma or demyelinating disease. The technical and logistic considerations for transplanting GPCs are extensive and crucial for optimizing and maintaining cell survival before and after transplantation, promoting myelination, and tracking the fate of transplanted cells. This is especially true in trials of GPC transplantation in combination with other strategies such as neutralization of inhibitors to axonal regeneration or remyelination. Overall, such studies improve our understanding and approach to developing clinically relevant therapies for axonal remyelination following traumatic brain injury (TBI) or spinal cord injury (SCI) and demyelinating diseases such as MS.