Developments in intracerebral stem cell grafts

Neuroprotective effect of tanshinone IIA-modified mesenchymal stem cells in a lipopolysaccharide-induced neuroinflammation model

In this study, the neuroprotective potential of tanshinone IIA (TIIA)-modified mesenchymal stem cells (MSC) were investigated using a murine model of lipopolysaccharide (LPS)-induced neuroinflammation. The cognitive performance of the mice was assessed using the Y-maze and Morris water maze tests, while immunofluorescence and Western blot analyses were employed to evaluate the hippocampal expression of pertinent markers and inflammatory factors, respectively. The results from the behavioral experiments demonstrated discernible differences in learning and memory abilities between the model group and the control group (P < 0.05), confirming the successful induction of neuroinflammation. Both the MSC and TIIA-MSC groups exhibited enhancements in the cognitive abilities of neuroinflammatory mice, with the TIIA-MSC group demonstrating a more pronounced improvement (P < 0.01). Immunofluorescence analysis revealed significant activation of microglia in the model group, while the MSC and TIIA-MSC groups exhibited a reduction in hippocampal microglial activation, with the TIIA-MSC group displaying a more substantial decrease. A statistically significant difference in the expression levels of IL-1, IL-6, and TNF-α was observed between the model and control groups (P < 0.05), indicating that IL-1, IL-6, and TNF-α were downregulated in both the MSC and TIIA-MSC groups. Notably, the downregulatory effect was more prominent in the TIIA-MSC group (P < 0.01). Compared to MSC treatment alone, the administration of TIIA-modified MSC demonstrated a superior protective effect against lipopolysaccharide-induced neuroinflammation. These findings underscore the potential therapeutic efficacy of TIIA-modified MSC in mitigating neuroinflammatory responses.

Functional Mechanism of Bone Marrow-Derived Mesenchymal Stem Cells in the Treatment of Animal Models with Alzheimer's Disease: Inhibition of Neuroinflammation

The transplantation of bone marrow-derived mesenchymal stem cells (BMMSCs) alleviates neuropathology and improves cognitive deficits in animal models with Alzheimer’s disease. However, the underlying mechanisms remain to be determined. Available data demonstrate transplanted BMMSCs can inhibit neuroinflammation, which may be related to microglial M1/M2 polarization and is regulated by the secretion of autocrine and paracrine cytokines. BMMSCs also mitigate Aβ plaques and Tau tangles in the brain, which may be associated with the recruitment of peripheral blood monocytes and the subsequent comprehensive effects. The therapeutic effects of stem cells involve potential mechanisms such as immunomodulation, apoptosis, and proliferation. BMMSC-mediated functional reconstruction through dynamic remodeling develops a novel balance. Herein, present review recapitulates the molecular basis of BMMSC-assisted biological processes and summarizes the possible mechanisms related to the interaction between BMMSCs and microglia. The transplanted BMMSCs can suppress neuroinflammation that plays a key role in the pathogenesis of Alzheimer’s disease.

Intranasal Transplantation of Human Neural Stem Cells Ameliorates Alzheimer's Disease-Like Pathology in a Mouse Model

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by memory impairments, which has no effective therapy. Stem cell transplantation shows great potential in the therapy of various disease. However, the application of stem cell therapy in neurological disorders, especially the ones with a long-term disease course such as AD, is limited by the delivery approach due to the presence of the brain blood barrier. So far, the most commonly used delivery approach in the therapy of neurological disorders with stem cells in preclinical and clinical studies are intracranial injection and intrathecal injection, both of which are invasive. In the present study, we use repetitive intranasal delivery of human neural stem cells (hNSCs) to the brains of APP/PS1 transgenic mice to investigate the effect of hNSCs on the pathology of AD. The results indicate that the intranasally transplanted hNSCs survive and exhibit extensive migration and higher neuronal differentiation, with a relatively limited glial differentiation. A proportion of intranasally transplanted hNSCs differentiate to cholinergic neurons, which rescue cholinergic dysfunction in APP/PS1 mice. In addition, intranasal transplantation of hNSCs attenuates β-amyloid accumulation by upregulating the expression of β-amyloid degrading enzymes, insulin-degrading enzymes, and neprilysin. Moreover, intranasal transplantation of hNSCs ameliorates other AD-like pathology including neuroinflammation, cholinergic dysfunction, and pericytic and synaptic loss, while enhancing adult hippocampal neurogenesis, eventually rescuing the cognitive deficits of APP/PS1 transgenic mice. Thus, our findings highlight that intranasal transplantation of hNSCs benefits cognition through multiple mechanisms, and exhibit the great potential of intranasal administration of stem cells as a non-invasive therapeutic strategy for AD.

Transplantation of bone marrow mesenchymal stem cells improves cognitive deficits and alleviates neuropathology in animal models of Alzheimer's disease: a meta-analytic review on potential mechanisms

BACKGROUND

Alzheimer's disease is a neurodegenerative disorder. Therapeutically, a transplantation of bone marrow mesenchymal stem cells (BMMSCs) can play a beneficial role in animal models of Alzheimer's disease. However, the relevant mechanism remains to be fully elucidated.

MAIN BODY

Subsequent to the transplantation of BMMSCs, memory loss and cognitive impairment were significantly improved in animal models with Alzheimer's disease (AD). Potential mechanisms involved neurogenesis, apoptosis, angiogenesis, inflammation, immunomodulation, etc. The above mechanisms might play different roles at certain stages. It was revealed that the transplantation of BMMSCs could alter some gene levels. Moreover, the differential expression of representative genes was responsible for neuropathological phenotypes in Alzheimer's disease, which could be used to construct gene-specific patterns.

CONCLUSIONS

Multiple signal pathways involve therapeutic mechanisms by which the transplantation of BMMSCs improves cognitive and behavioral deficits in AD models. Gene expression profile can be utilized to establish statistical regression model for the evaluation of therapeutic effect. The transplantation of autologous BMMSCs maybe a prospective therapy for patients with Alzheimer's disease.

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.

Treating childhood traumatic brain injury with autologous stem cell therapy

INTRODUCTION

Neonatal traumatic brain injury (TBI) is a significant cause of developmental disorders. Autologous stem cell therapy may enhance neonatal brain plasticity towards repair of the injured neonatal brain.

AREAS COVERED

The endogenous neonatal anti-inflammatory response can be enhanced through the delivery of anti-inflammatory agents. Stem cell therapy stands as a robust approach for sequestering the inflammation-induced cell death in the injured brain. Here, we discuss the use of umbilical cord blood cells and bone marrow stromal cells for acute and chronic treatment of experimental neonatal TBI. Autologous stem cell transplantation may dampen neuroinflammation. Clinical translation of this stem cell therapy will require identifying the therapeutic window post-injury and harvesting ample supply of transplantable autologous stem cells. Stem cell banking of cryopreserved cells may allow readily available transplantable cells and circumvent the unpredictable nature of neonatal TBI. Harnessing the anti-inflammatory properties of stem cells is key in combating the progressive neurodegeneration after the initial injury.

EXPERT OPINION

Combination treatments, such as with hypothermia, may enhance the therapeutic effects of stem cells. Stem cell therapy has immense potential as a stand-alone or adjunctive therapy for treating neuroinflammation associated with neonatal TBI acutely and for preventing further progression of the injury.

Translational considerations in injectable cell-based therapeutics for neurological applications: concepts, progress and challenges

Significant progress has been made during the past decade towards the clinical adoption of cell-based therapeutics. However, existing cell-delivery approaches have shown limited success, with numerous studies showing fewer than 5% of injected cells persisting at the site of injection within days of transplantation. Although consideration is being increasingly given to clinical trial design, little emphasis has been given to tools and protocols used to administer cells. The different behaviours of various cell types, dosing accuracy, precise delivery, and cell retention and viability post-injection are some of the obstacles facing clinical translation. For efficient injectable cell transplantation, accurate characterisation of cellular health post-injection and the development of standardised administration protocols are required. This review provides an overview of the challenges facing effective delivery of cell therapies, examines key studies that have been carried out to investigate injectable cell delivery, and outlines opportunities for translating these findings into more effective cell-therapy interventions.

Self-assembled amphiphilic core-shell nanocarriers in line with the modern strategies for brain delivery

Disorders of the central nervous system (CNS) represent increasing social and economic problems all over the world which makes the effective transport of drugs to the brain a crucial need. In the last decade, many strategies were introduced to deliver drugs to the brain trying to overcome the challenge of the blood brain barrier (BBB) using both invasive and non-invasive methods. Non-invasive strategy represented in the application of nanocarriers became very common. One of the most hopeful nanoscopic carriers for brain delivery is core-shell nanocarriers or polymeric micelles (PMs). They are more advantageous than other nanocarriers. They offer small size, ease of preparation, ease of sterilization and the possibility of surface modification with various ligands. Hence, the aim of this review is to discuss modern strategies for brain delivery, micelles as a successful delivery system for the brain and how micelles could be modified to act as "magic bullets" for brain delivery.

Cell therapies administered in the chronic phase after stroke: a meta-analysis examining safety and efficacy

Aim: To assess the safety and efficacy of cell therapies for chronic stroke. Methodology: Five databases were searched for treatments administered >90 days post-stroke. Reporting quality, adherence to research guidelines, treatment safety (risk ratios/pooled incidence rates) and neurological/functional efficacy (Hedge’s g) were all evaluated. Results: Twenty-three studies examined 17 treatments. Reporting quality scores were medium to high, but adherence to recommended guidelines was lower. Three treatments resulted in serious adverse events; four improved outcomes more than standard care. However, many studies were under-powered and individual patients varied in their response to some treatments. Conclusion: Preliminary findings suggest that some cell therapies may be relatively safe and effective, but larger double-blinded placebo-controlled studies are needed to establish the long-term risks and benefits.

Administrations of human adult ischemia-tolerant mesenchymal stem cells and factors reduce amyloid beta pathology in a mouse model of Alzheimer's disease

The impact of human adult ischemia-tolerant mesenchymal stem cells (hMSCs) and factors (stem cell factors) on cerebral amyloid beta (Aβ) pathology was investigated in a mouse model of Alzheimer's disease (AD). To this end, hMSCs were administered intravenously to APPPS1 transgenic mice that normally develop cerebral Aβ. Quantitative reverse transcriptase polymerase chain reaction biodistribution revealed that intravenously delivered hMSCs were readily detected in APPPS1 brains 1 hour following administration, and dropped to negligible levels after 1 week. Notably, intravenously injected hMSCs that migrated to the brain region were localized in the cerebrovasculature, but they also could be observed in the brain parenchyma particularly in the hippocampus, as revealed by immunohistochemistry. A single hMSC injection markedly reduced soluble cerebral Aβ levels in APPPS1 mice after 1 week, although increasing several Aβ-degrading enzymes and modulating a panel of cerebral cytokines, suggesting an amyloid-degrading and anti-inflammatory impact of hMSCs. Furthermore, 10 weeks of hMSC treatment significantly reduced cerebral Aβ plaques and neuroinflammation in APPPS1 mice, without increasing cerebral amyloid angiopathy or microhemorrhages. Notably, a repeated intranasal delivery of soluble factors secreted by hMSCs in culture, in the absence of intravenous hMSC injection, was also sufficient to diminish cerebral amyloidosis in the mice. In conclusion, this preclinical study strongly underlines that cerebral amyloidosis is amenable to therapeutic intervention based on peripheral applications of hMSC or hMSC factors, paving the way for a novel therapy for Aβ amyloidosis and associated pathologies observed in AD.

Growth factor therapy sequesters inflammation in affording neuroprotection in cerebrovascular diseases

INTRODUCTION

In recent years, accumulating evidence has demonstrated the key role of inflammation in the progression of cerebrovascular diseases. Inflammation can persist over prolonged period of time after the initial insult providing a wider therapeutic window. Despite the acute endogenous upregulation of many growth factors after the injury, it is not sufficient to protect against inflammation and to regenerate the brain. Therapeutic approaches targeting both dampening inflammation and enhancing growth factors are likely to provide beneficial outcomes in cerebrovascular disease.

AREAS COVERED

In this mini review, we discuss major growth factors and their beneficial properties to combat the inflammation in cerebrovascular diseases. Emerging biotechnologies which facilitate the therapeutic effects of growth factors are also presented in an effort to provide insights into the future combination therapies incorporating both central and peripheral abrogation of inflammation. Expert commentary: Many studies discussed in this review have demonstrated the therapeutic effects of growth factors in treating cerebrovascular diseases. It is unlikely that one growth factor can be used to treat these complex diseases. Combination of growth factors and anti-inflammatory modulators may clinically improve outcomes for patients. In particular, transplantation of stem cells may be able to achieve both goals of modulating inflammation and upregulating growth factors. Large preclinical studies and multiple laboratory collaborations are needed to advance these findings from bench to bedside.

Neural and mesenchymal stem cells in animal models of Huntington's disease: past experiences and future challenges

Huntington's disease (HD) is an inherited disease that causes progressive nerve cell degeneration. It is triggered by a mutation in the HTT gene that strongly influences functional abilities and usually results in movement, cognitive and psychiatric disorders. HD is incurable, although treatments are available to help manage symptoms and to delay the physical, mental and behavioral declines associated with the condition. Stem cells are the essential building blocks of life, and play a crucial role in the genesis and development of all higher organisms. Ablative surgical procedures and fetal tissue cell transplantation, which are still experimental, demonstrate low rates of recovery in HD patients. Due to neuronal cell death caused by accumulation of the mutated huntingtin (mHTT) protein, it is unlikely that such brain damage can be treated solely by drug-based therapies. Stem cell-based therapies are important in order to reconstruct damaged brain areas in HD patients. These therapies have a dual role: stem cell paracrine action, stimulating local cell survival, and brain tissue regeneration through the production of new neurons from the intrinsic and likely from donor stem cells. This review summarizes current knowledge on neural stem/progenitor cell and mesenchymal stem cell transplantation, which has been carried out in several animal models of HD, discussing cell distribution, survival and differentiation after transplantation, as well as functional recovery and anatomic improvements associated with these approaches. We also discuss the usefulness of this information for future preclinical and clinical studies in HD.

Post-stroke transplantation of adult subventricular zone derived neural progenitor cells--A comprehensive analysis of cell delivery routes and their underlying mechanisms

With neuroprotective approaches having failed until recently, current focus on experimental stroke research has switched towards manipulation of post-ischemic neuroregeneration. Transplantation of subventricular zone (SVZ) derived neural progenitor cells (NPCs) is a promising strategy for promotion of neurological recovery. Yet, fundamental questions including the optimal cell delivery route still have to be addressed. Consequently, male C57BL6 mice were exposed to transient focal cerebral ischemia and allowed to survive for as long as 84 days post-stroke. At 6h post-stroke, NPCs were grafted using six different cell delivery routes, i.e., intravenous, intraarterial, ipsilateral intrastriatal, contralateral intrastriatal, ipsilateral intraventricular and ipsilateral intracortical injection. Control mice received PBS only using the aforementioned delivery routes. Intralesional numbers of GFP(+) NPCs were high only after ipsilateral intrastriatal transplantation, whereas other injection paradigms only yielded comparatively small numbers of grafted cells. However, acute neuroprotection and improved functional outcome were observed after both systemic (i.e., intraarterial and intravenous) and ipsilateral intrastriatal transplantation only. Whereas systemic cell delivery induced acute and long-term neuroprotection, reduction of brain injury after ipsilateral intrastriatal cell grafting was only temporary, in line with the loss of transplanted NPCs in the brain. Both systemic and ipsilateral intrastriatal NPC delivery reduced microglial activation and leukocyte invasion, thus reducing free radical formation within the ischemic brain. On the contrary, only systemic NPC administration stabilized the blood-brain-barrier and reduced leukocytosis in the blood. Although intraarterial NPC transplantation was as effective as intravenous cell grafting, mortality of stroke mice was high using the intraarterial delivery route. Consequently, intravenous delivery of native NPCs in our experimental model is an attractive and effective strategy for stroke therapy that deserves further proof-of-concept studies.