Creatine Supplementation Improves Dopaminergic Cell Survival and Protects against MPP+ Toxicity in an Organotypic Tissue Culture System

Modulation of choline and lactate metabolism by basic fibroblast growth factor mitigates neuroinflammation in type 2 diabetes: Insights from 1H-NMR metabolomics analysis

BACKGROUND

Type 2 diabetes (T2D), a chronic metabolic disease, occurs brain dysfunction accompanied with neuroinflammation and metabolic disorders. The neuroprotective effects of the basic fibroblast growth factor (bFGF) have been well studied. However, the mechanism underlying the anti-inflammatory effects of bFGF remains elusive.

METHODS

In this study, db/db mice were employed as an in vivo model, while high glucose (HG)-induced SY5Y cells and LPS-induced BV2 cells were used as in vitro models. Liposomal transfection of MyD88 DNA plasmid was used for MyD88-NF-κB pathway studies. And western blotting, flow cytometry and qPCR were employed. 1H-NMR metabolomics was used to find out metabolic changes.

RESULTS

bFGF mitigated neuroinflammatory and metabolic disorders by inhibiting cortical inflammatory factor secretion and microglia hyperactivation in the cortex of db/db mice. Also, bFGF was observed to inhibit the MyD88-NF-κB pathway in high glucose (HG)-induced SY5Y cells and LPS-induced BV2 cells in in vitro experiments. Moreover, the 1H-NMR metabolomics results showed that discernible disparities between the cortical metabolic profiles of bFGF-treated db/db mice and their untreated counterparts. Notably, excessive lactate and choline deficiency attenuated the anti-inflammatory protective effect of bFGF in SY5Y cells.

CONCLUSION

bFGF ameliorates neuroinflammation in db/db mice by inhibiting the MyD88-NF-kB pathway. This finding expands the potential application of bFGF in the treatment of neuroinflammation-related cognitive dysfunction.

Metabolomics in degenerative brain diseases

Among the most studied diseases that affect the central nervous system are Parkinson's, Alzheimer's, and Huntington's diseases, but the lack of effective biomarkers, accurate diagnosis, and precise treatment for each of them is currently an issue. Due to the contribution of biomarkers in supporting diagnosis, many recent efforts have focused on their identification and validation at the beginning or during the progression of the mental illness. Metabolome reveals the metabolic processes that result from protein activities under the guided gene expression and environmental factors, either in healthy or pathological conditions. In this context, metabolomics has proven to be a valuable approach. Currently, magnetic resonance spectroscopy (NMR) and mass spectrometry (MS) are the most commonly used bioanalytical techniques for metabolomics. MS-assisted profiling is considered the most versatile technique, and the NMR is the most reproductive. However, each one of them has its drawbacks. In this review, we summarized several alterations in metabolites that have been reported for these three classic brain diseases using MS and NMR-based research, which might suggest some possible biomarkers to support the diagnosis and/or new targets for their treatment.

The Evolving Applications of Creatine Supplementation: Could Creatine Improve Vascular Health?

Creatine is a naturally occurring compound, functioning in conjunction with creatine kinase to play a quintessential role in both cellular energy provision and intracellular energy shuttling. An extensive body of literature solidifies the plethora of ergogenic benefits gained following dietary creatine supplementation; however, recent findings have further indicated a potential therapeutic role for creatine in several pathologies such as myopathies, neurodegenerative disorders, metabolic disturbances, chronic kidney disease and inflammatory diseases. Furthermore, creatine has been found to exhibit non-energy-related properties, such as serving as a potential antioxidant and anti-inflammatory. Despite the therapeutic success of creatine supplementation in varying clinical populations, there is scarce information regarding the potential application of creatine for combatting the current leading cause of mortality, cardiovascular disease (CVD). Taking into consideration the broad ergogenic and non-energy-related actions of creatine, we hypothesize that creatine supplementation may be a potential therapeutic strategy for improving vascular health in at-risk populations such as older adults or those with CVD. With an extensive literature search, we have found only four clinical studies that have investigated the direct effect of creatine on vascular health and function. In this review, we aim to give a short background on the pleiotropic applications of creatine, and to then summarize the current literature surrounding creatine and vascular health. Furthermore, we discuss the varying mechanisms by which creatine could benefit vascular health and function, such as the impact of creatine supplementation upon inflammation and oxidative stress.

Creatine is Neuroprotective to Retinal Neurons In Vitro But Not In Vivo

Purpose

To investigate the neuroprotective properties of creatine in the retina using in vitro and in vivo models of injury.

Methods

Two different rat retinal culture systems (one containing retinal ganglion cells [RGC] and one not) were subjected to either metabolic stress, via treatments with the mitochondrial complex IV inhibitor sodium azide, or excitotoxic stress, via treatment with N-methyl-D-aspartate for 24 hours, in the presence or absence of creatine (0.5, 1.0, and 5.0 mM). Neuronal survival was assessed by immunolabeling for cell-specific antigens. Putative mechanisms of creatine action were investigated in vitro. Expression of creatine kinase (CK) isoenzymes in the rat retina was examined using Western blotting and immunohistochemistry. The effect of oral creatine supplementation (2%, wt/wt) on retinal and blood creatine levels was determined as well as RGC survival in rats treated with N-methyl-D-aspartate (NMDA; 10 nmol) or high IOP-induced ischemia reperfusion.

Results

Creatine significantly prevented neuronal death induced by sodium azide and NMDA in both culture systems. Creatine administration did not alter cellular adenosine triphosphate (ATP). Inhibition of CK blocked the protective effect of creatine. Retinal neurons, including RGCs, expressed predominantly mitochondrial CK isoforms, while glial cells expressed exclusively cytoplasmic CKs. In vivo, NMDA and ischemia reperfusion caused substantial loss of RGCs. Creatine supplementation led to elevated blood and retinal levels of this compound but did not significantly augment RGC survival in either model.

Conclusions

Creatine increased neuronal survival in retinal cultures; however, no significant protection of RGCs was evident in vivo, despite elevated levels of this compound being present in the retina after oral supplementation.

Conditioned medium from Endothelial Progenitor Cells promotes number of dopaminergic neurons and exerts neuroprotection in cultured ventral mesencephalic neuronal progenitor cells

Transplantation of stem and progenitor cells offers a promising tool for brain repair in the context of neuropathological disorders including Parkinson's disease. There is growing proof that the capacity of adult stem and progenitor cells for tissue regeneration relies rather on the release of paracrine factors than on their cell replacement properties. In line with this notion, we have previously reported that conditioned medium (CM) collected from cultured Endothelial Progenitor Cells (EPC) stimulated survival of striatal neurons. In the present study we investigated whether EPC-CM promotes survival of cultured midbrain progenitor cells. For that purpose primary cultures from fetal rat embryonic ventral mesencephalon (VM) were prepared and grown for 7 days in vitro (DIV). EPC-CM was administered from DIV5-7. First, we found that EPC-CM treatment resulted in significantly increased cell densities of TH-ir neurons. Interestingly, this effect was no longer seen after proteolytic digestion of the EPC-CM. EPC-CM also significantly increased densities of beta-III-tubulin positive neurons and lba-1-ir microglial cells. The effect on dopaminergic neurons was not due to higher cell proliferation as no incorporation of EdU was observed in TH-ir cells. Importantly, EPC-CM exerted neuroprotection against MPP+ induced toxicity as in vitro model of Parkinson's disease. Taken together, our findings identified EPC-CM as a powerful tool to promote survival of cultured VM neurons and further support the importance of paracrine factors in the actions of stem and progenitor cells for brain repair.

Creatine as a Neuroprotector: an Actor that Can Play Many Parts

Creatine is a nitrogenous organic acid that plays a central role as an energy buffer in high energy demanding systems, including the muscular and the central nervous system. It can be acquired from diet or synthesized endogenously, and its main destination is the system creatine/phosphocreatine that strengthens cellular energetics via a temporal and spatial energy buffer that can restore cellular ATP without a reliance on oxygen. This compound has been proposed to possess secondary roles, such as direct and indirect antioxidant, immunomodulatory agent, and possible neuromodulator. However, these effects may be associated with its bioenergetic role in the mitochondria. Given the fundamental roles that creatine plays in the CNS, several preclinical and clinical studies have tested the potential that creatine has to treat degenerative disorders. However, although in vitro and in vivo animal models are highly encouraging, most clinical trials fail to reproduce positive results suggesting that the prophylactic use for neuroprotection in at-risk populations or patients is the most promising field. Nonetheless, the only clearly positive data of the creatine supplementation in human beings are related to the (rare) creatine deficiency syndromes. It seems critical that future studies must establish the best dosage regime to increase brain creatine in a way that can relate to animal studies, provide new ways for creatine to reach the brain, and seek larger experimental groups with biomarkers for prediction of efficacy.

Endothelial Progenitor Cells Conditioned Medium Supports Number of GABAergic Neurons and Exerts Neuroprotection in Cultured Striatal Neuronal Progenitor Cells

There is growing evidence that stem and progenitor cells exert regenerative actions by means of paracrine factors. In line with these notions, we recently demonstrated that endothelial progenitor cell (EPC)-derived conditioned medium (EPC-CM) substantially increased viability of brain microvascular cells. In the present study, we aimed at investigating whether EPC-CM supports cell survival of cultured striatal progenitor cells. For that purpose, primary cultures from fetal rat embryonic (E14) ganglionic eminence were prepared and grown for 7 days in vitro (DIV). EPC-CM was administered from DIV5–7. Treatment of the striatal cultures with EPC-CM resulted in significantly increased densities of GABA-immunoreactive (-ir) neurons. Inhibition of mitogen-activated protein kinase and phosphatidylinositol-3-kinase, but not of the ROCK pathway, significantly attenuated the EPC-CM induced increase in GABA-ir cell densities. Similar results were observed when EPC-CM was subjected to proteolytic digestion and lipid extraction. Furthermore, inhibition of translation abolished the EPC-CM induced effects. Importantly, EPC-CM displayed neuroprotection against 3-nitropropionic acid induced toxicity. These findings demonstrate that EPC-derived paracrine factors substantially promote survival and/or differentiation of cultured striatal progenitor cells involving both proteinaceous factors and lipidic factors. In sum, EPC-CM constituents might lead to a novel cell-free therapeutic strategy to challenge neuronal degeneration.

Mitochondrial dynamics, a key executioner in neurodegenerative diseases

Neurodegenerative diseases (NDs) are the group of disorder that includes brain, peripheral nerves, spinal cord and results in sensory and motor neuron dysfunction. Several studies have shown that mitochondrial dynamics and their axonal transport play a central role in most common NDs such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD) and Amyotrophic Lateral Sclerosis (ALS) etc. In normal physiological condition, there is a balance between mitochondrial fission and fusion process while any alteration to these processes cause defect in ATP (Adenosine Triphosphate) biogenesis that lead to the onset of several NDs. Also, mitochondria mediated ROS may induce lipid and protein peroxidation, energy deficiency environment in the neurons and results in cell death and defective neurotransmission. Though, mitochondria is a well-studied cell organelle regulating the cellular energy demands but still, its detail role or association in NDs is under observation. In this review, we have summarized an updated mitochondria and their possible role in different NDs with the therapeutic strategy to improve the mitochondrial functions.

Production, characterization and toxicology assay of creatine pegylated nanoliposome with polysorbate 80 for brain delivery

Creatine acts intracellularly as energy buffer and storage, demonstrating protective effects in animal models of neurodegenerative diseases. However, its permeability throught blood-brain barrier (BBB) is reduced. The aim of the present study was developing a carrier to facilitate the delivery of creatine to the central nervous system. Creatine nanoliposomes were produced, characterized and assayed in models of toxicity in vitro and in vivo. Particles showed negative zeta potential (-12,5 mV), polydispersity index 0.237 and medium-size of 105 nm, which was confirmed by transmission electron microscopy (TEM) images. Toxicity assay in vitro was evaluated with blank liposomes (no drug) or creatine nanoliposomes at concentrations of 0.02 and 0.2 mg/mL, that did not influence the viability of Vero cells. The result. of the comet assay that the nanoliposomes are not genotoxic, togeher with cell viability demonstrated that the nanoliposomes are not toxic. Besides, in vivo assays not demonstrate toxicity in hematological and biochemical markers of young rats. Nevertheless, increase content of creatine in the cerebral cortex tissue after subchronic treatment was observed. Altogether, results indicate increase permeability of creatine to the BBB that could be used as assay for in vivo studies to confirm improved effect than free creatine.

Metabolic Dysfunction in Parkinson's Disease: Bioenergetics, Redox Homeostasis and Central Carbon Metabolism

The loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and the accumulation of protein inclusions (Lewy bodies) are the pathological hallmarks of Parkinson's disease (PD). PD is triggered by genetic alterations, environmental/occupational exposures and aging. However, the exact molecular mechanisms linking these PD risk factors to neuronal dysfunction are still unclear. Alterations in redox homeostasis and bioenergetics (energy failure) are thought to be central components of neurodegeneration that contribute to the impairment of important homeostatic processes in dopaminergic cells such as protein quality control mechanisms, neurotransmitter release/metabolism, axonal transport of vesicles and cell survival. Importantly, both bioenergetics and redox homeostasis are coupled to neuro-glial central carbon metabolism. We and others have recently established a link between the alterations in central carbon metabolism induced by PD risk factors, redox homeostasis and bioenergetics and their contribution to the survival/death of dopaminergic cells. In this review, we focus on the link between metabolic dysfunction, energy failure and redox imbalance in PD, making an emphasis in the contribution of central carbon (glucose) metabolism. The evidence summarized here strongly supports the consideration of PD as a disorder of cell metabolism.

Nogo-receptor 1 antagonization in combination with neurotrophin-4/5 is not superior to single factor treatment in promoting survival and morphological complexity of cultured dopaminergic neurons

Cell transplantation using ventral mesencephalic tissue is an experimental approach to treat Parkinson's disease. This approach is limited by poor survival of the transplants and the high number of dopaminergic neurons needed for grafting. Increasing the yield of dopaminergic neurons in donor tissue is of great importance. We have previously shown that antagonization of the Nogo-receptor 1 by NEP1-40 promoted survival of cultured dopaminergic neurons and exposure to neurotrophin-4/5 increased dopaminergic cell densities in organotypic midbrain cultures. We investigated whether a combination of both treatments offers a novel tool to further improve dopaminergic neuron survival. Rat embryonic ventral mesencephalic neurons grown as organotypic free-floating roller tube or primary dissociated cultures were exposed to neurotrophin-4/5 and NEP1-40. The combined and single factor treatment resulted in significantly higher numbers of tyrosine hydroxylase positive neurons compared to controls. Significantly stronger tyrosine hydroxylase signal intensity was detected by Western blotting in the combination-treated cultures compared to controls but not compared to single factor treatments. Neurotrophin-4/5 and the combined treatment showed significantly higher signals for the neuronal marker microtubule-associated protein 2 in Western blots compared to control while no effects were observed for the astroglial marker glial fibrillary acidic protein between groups, suggesting that neurotrophin-4/5 targets mainly neuronal cells. Finally, NEP1-40 and the combined treatment significantly augmented tyrosine hydroxylase positive neurite length. Summarizing, our findings substantiate that antagonization of the Nogo-receptor 1 promotes dopaminergic neurons but does not further increase the yield of dopaminergic neurons and their morphological complexity when combined with neurotrophin-4/5 hinting to the idea that these treatments might exert their effects by activating common downstream pathways.

Creatine supplementation improves neural progenitor cell survival in Huntington's disease

Preclinical and clinical studies suggest that striatal transplantation of neural stem cells (NSCs) and neural progenitor cells (NPCs) may be an appealing and valuable system for treating Huntington's disease. Nevertheless, for a neural replacement to become an effective translational treatment for Huntington's disease, a certain number of difficulties must be addressed, including how to improve the integration of transplanted cell grafts with the host tissue, to elevate the survival rates of transplanted cells, and to ensure their directed differentiation into specific neuronal phenotypes. Research focusing on the translational applications of creatine (Cr) supplementation in NSC and NPC cell replacement therapies continues to offer promising results, pointing to Cr as a factor with the potential to improve cell graft survivability and encourage differentiation toward GABAergic phenotypes in models of striatal transplantation. Here, we evaluate research examining the outcomes of Cr supplementation and how the timing of supplementation regimes may affect their efficacy. The recent studies indicate that Cr's effects vary according to the developmental stage of the cells being treated, noting the dynamic differences in creatine kinase expression over the developmental stages of differentiating NPCs. This research continues to move Cr supplementation closer to the widespread clinical application and suggests such techniques warrant further examination.

Beyond muscles: The untapped potential of creatine

Creatine is widely used by both elite and recreational athletes as an ergogenic aid to enhance anaerobic exercise performance. Older individuals also use creatine to prevent sarcopenia and, accordingly, may have therapeutic benefits for muscle wasting diseases. Although the effect of creatine on the musculoskeletal system has been extensively studied, less attention has been paid to its potential effects on other physiological systems. Because there is a significant pool of creatine in the brain, the utility of creatine supplementation has been examined in vitro as well as in vivo in both animal models of neurological disorders and in humans. While the data are preliminary, there is evidence to suggest that individuals with certain neurological conditions may benefit from exogenous creatine supplementation if treatment protocols can be optimized. A small number of studies that have examined the impact of creatine on the immune system have shown an alteration in soluble mediator production and the expression of molecules involved in recognizing infections, specifically toll-like receptors. Future investigations evaluating the total impact of creatine supplementation are required to better understand the benefits and risks of creatine use, particularly since there is increasing evidence that creatine may have a regulatory impact on the immune system.

The effects of creatine supplementation on striatal neural progenitor cells depend on developmental stage

Transplantation of neural progenitor cells (NPCs) is a promising experimental therapy for Huntington's disease (HD). The variables responsible for the success of this approach, including selection of the optimal developmental stage of the grafted cells, are however largely unknown. Supporting cellular energy metabolism by creatine (Cr) supplementation is a clinically translatable method for improving cell transplantation strategies. The present study aims at investigating differences between early (E14) and late (E18) developmental stages of rat striatal NPCs in vitro. NPCs were isolated from E14 and E18 embryos and cultured for 7 days with or without Cr [5 mM]. Chronic treatment significantly increased the percentage of GABA-immunoreactive neurons as compared to untreated controls, both in the E14 (170.4 ± 4.7 %) and the E18 groups (129.3 ± 9.3 %). This effect was greater in E14 cultures (p < 0.05). Similarly, short-term treatment for 24 h resulted in increased induction (p < 0.05) of the GABA-ergic phenotype in E14 (163.0 ± 10.4 %), compared to E18 cultures (133.3 ± 9.5 %). Total neuronal cell numbers and general viability were not affected by Cr (p > 0.05). Protective effects of Cr against a metabolic insult were equal in E14 and E18 NPCs (p > 0.05). Cr exposure promoted morphological differentiation of GABA-ergic neurons, including neurite length in both groups (p < 0.05), but the number of branching points was increased only in the E18 group (p < 0.05). Our results demonstrate that the role of Cr as a GABA-ergic differentiation factor depends on the developmental stage of striatal NPCs, while Cr-mediated neuroprotection is not significantly influenced. These findings have potential implications for optimizing future cell replacement strategies in HD.

Organotypic Cultures as a Model to Study Adult Neurogenesis in CNS Disorders

Neural regeneration resides in certain specific regions of adult CNS. Adult neurogenesis occurs throughout life, especially from the subgranular zone of hippocampus and the subventricular zone, and can be modulated in physiological and pathological conditions. Numerous techniques and animal models have been developed to demonstrate and observe neural regeneration but, in order to study the molecular and cellular mechanisms and to characterize multiple types of cell populations involved in the activation of neurogenesis and gliogenesis, investigators have to turn to in vitro models. Organotypic cultures best recapitulate the 3D organization of the CNS and can be explored taking advantage of many techniques. Here, we review the use of organotypic cultures as a reliable and well defined method to study the mechanisms of neurogenesis under normal and pathological conditions. As an example, we will focus on the possibilities these cultures offer to study the pathophysiology of diseases like Alzheimer disease, Parkinson's disease, and cerebral ischemia.

Both creatine and its product phosphocreatine reduce oxidative stress and afford neuroprotection in an in vitro Parkinson's model

Creatine is the substrate for creatine kinase in the synthesis of phosphocreatine (PCr). This energetic system is endowed of antioxidant and neuroprotective properties and plays a pivotal role in brain energy homeostasis. The purpose of this study was to investigate the neuroprotective effect of creatine and PCr against 6-hydroxydopamine (6-OHDA)-induced mitochondrial dysfunction and cell death in rat striatal slices, used as an in vitro Parkinson's model. The possible involvement of the signaling pathway mediated by phosphatidylinositol-3 kinase (PI3K), protein kinase B (Akt), and glycogen synthase kinase-3β (GSK3β) was also evaluated. Exposure of striatal slices to 6-OHDA caused a significant disruption of the cellular homeostasis measured as 3-(4,5 dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide reduction, lactate dehydrogenase release, and tyrosine hydroxylase levels. 6-OHDA exposure increased the levels of reactive oxygen species and thiobarbituric acid reactive substances production and decreased mitochondrial membrane potential in rat striatal slices. Furthermore, 6-OHDA decreased the phosphorylation of Akt (Serine(473)) and GSK3β (Serine(9)). Coincubation with 6-OHDA and creatine or PCr reduced the effects of 6-OHDA toxicity. The protective effect afforded by creatine or PCr against 6-OHDA-induced toxicity was reversed by the PI3K inhibitor LY294002. In conclusion, creatine and PCr minimize oxidative stress in striatum to afford neuroprotection of dopaminergic neurons.

The centrality of mitochondria in the pathogenesis and treatment of Parkinson's disease

Parkinson's disease (PD) is an incurable neurodegenerative disorder leading to progressive motor impairment and for which there is no cure. From the first postmortem account describing a lack of mitochondrial complex I in the substantia nigra of PD sufferers, the direct association between mitochondrial dysfunction and death of dopaminergic neurons has ever since been consistently corroborated. In this review, we outline common pathways shared by both sporadic and familial PD that remarkably and consistently converge at the level of mitochondrial integrity. Furthermore, such knowledge has incontrovertibly established mitochondria as a valid therapeutic target in neurodegeneration. We discuss several mitochondria-directed therapies that promote the preservation, rescue, or restoration of dopaminergic neurons and which have been identified in the laboratory and in preclinical studies. Some of these have progressed to clinical trials, albeit the identification of an unequivocal disease-modifying neurotherapeutic is still elusive. The challenge is therefore to improve further, not least by more research on the molecular mechanisms and pathophysiological consequences of mitochondrial dysfunction in PD.

Mitochondrial diseases of the brain

Neurodegenerative disorders are debilitating diseases of the brain, characterized by behavioral, motor and cognitive impairments. Ample evidence underpins mitochondrial dysfunction as a central causal factor in the pathogenesis of neurodegenerative disorders including Parkinson's disease, Huntington's disease, Alzheimer's disease, Amyotrophic lateral sclerosis, Friedreich's ataxia and Charcot-Marie-Tooth disease. In this review, we discuss the role of mitochondrial dysfunction such as bioenergetics defects, mitochondrial DNA mutations, gene mutations, altered mitochondrial dynamics (mitochondrial fusion/fission, morphology, size, transport/trafficking, and movement), impaired transcription and the association of mutated proteins with mitochondria in these diseases. We highlight the therapeutic role of mitochondrial bioenergetic agents in toxin and in cellular and genetic animal models of neurodegenerative disorders. We also discuss clinical trials of bioenergetics agents in neurodegenerative disorders. Lastly, we shed light on PGC-1α, TORC-1, AMP kinase, Nrf2-ARE, and Sirtuins as novel therapeutic targets for neurodegenerative disorders.

Metabolic pathway and distribution of superparamagnetic iron oxide nanoparticles: in vivo study

Background:

Experimental tissue fusion benefits from the selective heating of superparamagnetic iron oxide nanoparticles (SPIONs) under high frequency irradiation. However, the metabolic pathways of SPIONs for tissue fusion remain unknown. Hence, the goal of this in vivo study was to analyze the distribution of SPIONs in different organs by means of magnetic resonance imaging (MRI) and histological analysis after a SPION-containing patch implantation.

Methods:

SPION-containing patches were implanted in rats. Three animal groups were studied histologically over six months. Degradation assessment of the SPION-albumin patch was performed in vivo using MRI for iron content localization and biodistribution.

Results:

No SPION degradation or accumulation into the reticuloendothelial system was detected by MRI, MRI relaxometry, or histology, outside the area of the implantation patch. Concentrations from 0.01 μg/mL to 25 μg/mL were found to be hyperintense in T1-like gradient echo sequences. The best differentiation of concentrations was found in T2 relaxometry, susceptibility-sensitive gradient echo sequences, and in high repetition time T2 images. Qualitative and semiquantitative visualization of small concentrations and accumulation of SPIONs by MRI are feasible. In histological liver samples, Kupffer cells were significantly correlated with postimplantation time, but no differences were observed between sham-treated and induction/no induction groups. Transmission electron microscopy showed local uptake of SPIONs in macrophages and cells of the reticuloendothelial system. Apoptosis staining using caspase showed no increased toxicity compared with sham-treated tissue. Implanted SPION patches were relatively inert with slow, progressive local degradation over the six-month period. No distant structural alterations in the studied tissue could be observed.

Conclusion:

Systemic bioavailability may play a role in specific SPION implant toxicity and therefore the local degradation process is a further aspect to be assessed in future studies.

The creatine kinase system and pleiotropic effects of creatine

The pleiotropic effects of creatine (Cr) are based mostly on the functions of the enzyme creatine kinase (CK) and its high-energy product phosphocreatine (PCr). Multidisciplinary studies have established molecular, cellular, organ and somatic functions of the CK/PCr system, in particular for cells and tissues with high and intermittent energy fluctuations. These studies include tissue-specific expression and subcellular localization of CK isoforms, high-resolution molecular structures and structure–function relationships, transgenic CK abrogation and reverse genetic approaches. Three energy-related physiological principles emerge, namely that the CK/PCr systems functions as (a) an immediately available temporal energy buffer, (b) a spatial energy buffer or intracellular energy transport system (the CK/PCr energy shuttle or circuit) and (c) a metabolic regulator. The CK/PCr energy shuttle connects sites of ATP production (glycolysis and mitochondrial oxidative phosphorylation) with subcellular sites of ATP utilization (ATPases). Thus, diffusion limitations of ADP and ATP are overcome by PCr/Cr shuttling, as most clearly seen in polar cells such as spermatozoa, retina photoreceptor cells and sensory hair bundles of the inner ear. The CK/PCr system relies on the close exchange of substrates and products between CK isoforms and ATP-generating or -consuming processes. Mitochondrial CK in the mitochondrial outer compartment, for example, is tightly coupled to ATP export via adenine nucleotide transporter or carrier (ANT) and thus ATP-synthesis and respiratory chain activity, releasing PCr into the cytosol. This coupling also reduces formation of reactive oxygen species (ROS) and inhibits mitochondrial permeability transition, an early event in apoptosis. Cr itself may also act as a direct and/or indirect anti-oxidant, while PCr can interact with and protect cellular membranes. Collectively, these factors may well explain the beneficial effects of Cr supplementation. The stimulating effects of Cr for muscle and bone growth and maintenance, and especially in neuroprotection, are now recognized and the first clinical studies are underway. Novel socio-economically relevant applications of Cr supplementation are emerging, e.g. for senior people, intensive care units and dialysis patients, who are notoriously Cr-depleted. Also, Cr will likely be beneficial for the healthy development of premature infants, who after separation from the placenta depend on external Cr. Cr supplementation of pregnant and lactating women, as well as of babies and infants are likely to be of benefit for child development. Last but not least, Cr harbours a global ecological potential as an additive for animal feed, replacing meat- and fish meal for animal (poultry and swine) and fish aqua farming. This may help to alleviate human starvation and at the same time prevent over-fishing of oceans.

Mitochondria: a therapeutic target in neurodegeneration

Mitochondrial dysfunction has long been associated with neurodegenerative disease. Therefore, mitochondrial protective agents represent a unique direction for the development of drug candidates that can modify the pathogenesis of neurodegeneration. This review discusses evidence showing that mitochondrial dysfunction has a central role in the pathogenesis of Alzheimer's, Parkinson's and Huntington's diseases and amyotrophic lateral sclerosis. We also debate the potential therapeutic efficacy of metabolic antioxidants, mitochondria-directed antioxidants and Szeto-Schiller (SS) peptides. Since these compounds preferentially target mitochondria, a major source of oxidative damage, they are promising therapeutic candidates for neurodegenerative diseases. Furthermore, we will briefly discuss the novel action of the antihistamine drug Dimebon on mitochondria.

Cell death pathways in Parkinson's disease: role of mitochondria

Parkinson's disease (PD) is a progressive neurodegenerative disease and is characterized pathologically by selective loss of nigrostriatal dopaminergic neurons and the formation of Lewy bodies. Although in the majority of cases the cause of PD is unknown, mitochondrial dysfunction, environmental toxins, oxidative stress, and abnormal protein accumulation may all be involved in disease pathogenesis. The discovery of genes causing rare familial forms of PD (including alpha-synuclein, parkin, DJ-1, PINK1, and LRRK2) has shed light on our understanding of the molecular mechanisms of the development of the disease. Further studies from transgenic or toxin-induced experimental models have also provided insights into the etiology of human disease. Recently, accumulating evidence has suggested that mitochondrial dysfunction is one of the key players in molecular cell death pathways of PD. In this review, we provide an overview of the role of mitochondria in the pathogenesis of both sporadic and familial forms of PD. We also discuss the links between different pathways and highlight novel therapeutic opportunities which target mitochondria.

Mitochondrial approaches for neuroprotection

A large body of evidence from postmortem brain tissue and genetic analysis in humans and biochemical and pathological studies in animal models (transgenic and toxin) of neurodegeneration suggest that mitochondrial dysfunction is a common pathological mechanism. Mitochondrial dysfunction from oxidative stress, mitochondrial DNA deletions, pathological mutations, altered mitochondrial morphology, and interaction of pathogenic proteins with mitochondria leads to neuronal demise. Therefore, therapeutic approaches targeting mitochondrial dysfunction and oxidative damage hold great promise in neurodegenerative diseases. This review discusses the potential therapeutic efficacy of creatine, coenzyme Q10, idebenone, synthetic triterpenoids, and mitochondrial targeted antioxidants (MitoQ) and peptides (SS-31) in in vitro studies and in animal models of Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, and Alzheimer's disease. We have also reviewed the current status of clinical trials of creatine, coenzyme Q10, idebenone, and MitoQ in neurodegenerative disorders. Further, we discuss newly identified therapeutic targets, including peroxisome proliferator-activated receptor-gamma-coactivator and sirtuins, which provide promise for future therapeutic developments in neurodegenerative disorders.

Cell replacement therapy for intracerebral hemorrhage

✓ Intracerebral hemorrhage (ICH), for which no effective treatment strategy is currently available, constitutes one of the most devastating forms of stroke. As a result, developing therapeutic options for ICH is of great interest to the medical community. The 3 potential therapies that have the most promise are cell replacement therapy, enhancing endogenous repair mechanisms, and utilizing various neuroprotective drugs. Replacement of damaged cells and restoration of function can be accomplished by transplantation of cells derived from different sources, such as embryonic or somatic stem cells, umbilical cord blood, and genetically modified cell lines. Early experimental data showing the benefits of cell transplantation on functional recovery after ICH have been promising. Nevertheless, several studies have focused on another therapeutic avenue, investigating novel ways to activate and direct endogenous repair mechanisms in the central nervous system, through exposure to specific neuronal growth factors or by inactivating inhibitory molecules. Lastly, neuroprotective drugs may offer an additional tool for improving neuronal survival in the perihematomal area. However, a number of scientific issues must be addressed before these experimental techniques can be translated into clinical therapy. In this review, the authors outline the recent advances in the basic science of treatment strategies for ICH.

The neuroprotective role of creatine

Significant progress has been made in identifying neuroprotective agents and their translation to patients with neurological disorders. While the direct causative pathways of neurodegeneration remain unclear, they are under great clinical and experimental investigation. There are a number of interrelated pathogenic mechanisms triggering molecular events that lead to neuronal death. One putative mechanism reported to play a prominent role in the pathogenesis of neurological diseases is impaired energy metabolism. If reduced energy stores play a role in neuronal loss, then therapeutic strategies that buffer intracellular energy levels may prevent or impede the neurodegenerative process. Recent studies suggest that impaired energy production promotes neurological disease onset and progression. Sustained ATP levels are critical to cellular homeostasis and may have both direct and indirect influence on pathogenic mechanisms associated with neurological disorders. Creatine is a critical component in maintaining cellular energy homeostasis, and its administration has been reported to be neuroprotective in a wide number of both acute and chronic experimental models of neurological disease. In the context of this chapter, we will review the experimental evidence for creatine supplementation as a neurotherapeutic strategy in patients with neurological disorders, including Huntington's disease, Parkinson's disease, amyotrophic lateral sclerosis, and Alzheimer's disease, as well as in ischemic stroke, brain and spinal cord trauma, and epilepsy.

Creatine decreases convulsions and neurochemical alterations induced by glutaric acid in rats

Glutaric acidemia type I (GA-I) is an inherited metabolic disease characterized by striatal degeneration, seizures, and accumulation of glutaric acid (GA). Considering that GA impairs energy metabolism and induces reactive species generation, we investigated whether the acute administration of creatine, an amino acid with antioxidant and ergogenic properties, protects against the seizures and neurochemical alterations (inhibition of Na(+),K(+)-ATPase and increased protein carbonylation) induced by the intrastriatal injection of GA (4 micromol/striatum). We also investigated whether creatine protected against the GA-induced inhibition of glutamate uptake in vitro. Creatine administration (300 mg/kg, p.o.) decreased seizures (evidenced by electrographic changes), protein carbonylation and Na(+),K(+)-ATPase inhibition induced by GA. However, creatine, at a dose capable of fully preventing GA-induced protein carbonylation (50 and 150 mg/kg, p.o.), did not prevent convulsions and Na(+),K(+)-ATPase inhibition, suggesting that the anticonvulsant activity of creatine in this experimental model is not related to its antioxidant action. Creatine also protected against the GA-induced inhibition of l-[(3)H]glutamate uptake in synaptosomes, suggesting that creatine may reduce the deleterious effects of GA by maintaining glutamate uptake in the synaptic cleft. Therefore, considering that creatine significantly attenuates the deleterious effects of GA assessed by behavioral and neurochemical measures, it is plausible to propose the use of this amino acid as an adjuvant therapy in the management of glutaric acidemia.

Creatine treatment promotes differentiation of GABA-ergic neuronal precursors in cultured fetal rat spinal cord

Creatine is a substrate of cytosolic and mitochondrial creatine kinases. Its supplementation augments cellular levels of creatine and phosphocreatine, the rate of ATP resynthesis, and improves the function of the creatine kinase energy shuttle. High cytoplasmatic total creatine levels have been reported to be neuroprotective by inhibiting apoptosis. In addition, creatine has direct antioxidant effects, which may be of importance in amyotrophic lateral sclerosis. In the present study, we investigated the effects of creatine [5 mM] on survival and differentiation of cultured GABA-immunoreactive (-ir) and choline acetyltransferase (ChAT)-ir rat spinal cord neurons. Furthermore, we addressed the neuroprotective potential of creatine supplementation against 3-nitropropionic acid (3-NP) induced toxicity. General cell survival and total neuronal cell density were not altered by chronic creatine treatment. We found, however, after chronic creatine and short-term creatine exposure a significantly higher density of GABA-ir neurons hinting to a differentiation-inducing mechanism of creatine. This notion is further supported by a significant higher content of GAD after creatine exposure. Creatine supplementation also exerted a partial, but significant neuroprotection for GABA-ir neurons against 3-NP induced toxicity. Interestingly, chronic creatine treatment did not alter cell density of ChAT-ir neurons but promoted their morphologic differentiation. Cell soma size and number of primary neurites per neuron were increased significantly after creatine supplementation. Taken together, creatine supplementation promoted the differentiation or the survival of GABAergic neurons and resulted in partial neuroprotection against 3-NP induced toxicity. The data suggest that creatine may play a critical role during development of spinal cord neurons.

Creatine promotes the GABAergic phenotype in human fetal spinal cord cultures

In the present study, we investigated the expression pattern of cytosolic brain specific-BB-CK and ubiquitous mitochondrial-creatine kinases (uMt-CK) in developing human spinal cord. Consequently, we studied the effects of creatine treatment on cultured fetal human spinal cord tissue. We found that both CK isoforms were expressed in fetal spinal cord at all time points investigated (5 to 11.5 weeks post conception) and correspondingly specific CK activity was detected. Chronic creatine exposure resulted in significantly higher densities of GABA-immunoreactive neurons in the cultures, while total neuronal cell density was not altered, suggesting a differentiation inducing mechanism of creatine supplementation. Taken together, our observations favour the view that the creatine phosphocreatine system plays an important role in the developing CNS.

The creatine kinase/creatine connection to Alzheimer's disease: CK-inactivation, APP-CK complexes and focal creatine deposits

Cytosolic brain-type creatine kinase (BB-CK), which is coexpressed with ubiquitous mitochondrial uMtCK, is significantly inactivated by oxidation, in Alzheimer's disease (AD) patients. Since CK has been shown to play a fundamental role in cellular energetics of the brain, any disturbance of this enzyme may exasperate the AD disease process. Mutations in amyloid precursor protein (APP) are associated with early onset AD and result in abnormal processing of APP, and accumulation of A beta peptide, the main constituent of amyloid plaques in AD brain. Recent data on a direct interaction between APP and the precursor of uMtCK support an emerging relationship between AD, cellular energy levels and mitochondrial function. In addition, recently discovered creatine (Cr) deposits in the brain of transgenic AD mice, as well as in the hippocampus from AD patients, indicate a direct link between perturbed energy state, Cr metabolism and AD. Here, we review the roles of Cr and Cr-related enzymes and consider the potential value of supplementation with Cr, a potent neuroprotective substance. As a hypothesis, we consider whether Cr, if given at an early time point of the disease, may prevent or delay the course of AD-related neurodegeneration.