Survival rate improvement in a rat ischemia model by long circulating liposomes containing cytidine-5I-diphosphate choline

OX26-cojugated gangliosilated liposomes to improve the post-ischemic therapeutic effect of CDP-choline

Cerebrovascular impairment represents one of the main causes of death worldwide with a mortality rate of 5.5 million per year. The disability of 50% of surviving patients has high social impacts and costs in long period treatment for national healthcare systems. For these reasons, the efficacious clinical treatment of patients, with brain ischemic stroke, remains a medical need. To this aim, a liposome nanomedicine, with monosialic ganglioside type 1 (GM1), OX26 (an anti-transferrin receptor antibody), and CDP-choline (a neurotrophic drug) (CDP-choline/OX26Lip) was prepared. CDP-choline/OX26Lip were prepared by a freeze and thaw method and then extruded through polycarbonate filters, to have narrow size distributed liposomes of ~80 nm. CDP-choline/OX26Lip were stable in human serum, they had suitable pharmacokinetic properties, and 30.0 ± 4.2% of the injected drug was still present in the blood stream 12 h after its systemic injection. The post-ischemic therapeutic effect of CDP-choline/OX26Lip is higher than CDP-choline/Lip, thus showing a significantly high survival rate of the re-perfused post-ischemic rats, i.e. 96% and 78% after 8 days. The treatment with CDP-choline/OX26Lip significantly decreased the peroxidation rate of ~5-times compared to CDP-choline/Lip; and the resulting conjugated dienes, that was 13.9 ± 1.1 mmol/mg proteins for CDP-choline/Lip and 3.1 ± 0.8 for CDP-choline/OX26Lip. OX26 increased the accumulation of GM1-liposomes in the brain tissues and thus the efficacious of CDP-choline. Therefore, this nanomedicine may represent a strategy for the reassessment of CDP-choline to treat post-ischemic events caused by brain stroke, and respond to a significant clinical need.

Neuroprotection by Cerebrolysin and Citicoline Through the Upregulation of Brain-Derived Neurotrophic Factor (BDNF) Expression in the Affected Neural Cells: A Preliminary Clue Obtained Through an In Vitro Study

OBJECTIVES

Citicoline and cerebrolysin are two unique yet contentious medications because of inconsistencies in efficacy as well as the mystery surrounding their mode of action. The current study aimed to re-validate the neuroprotective benefits of these medications and investigate the possible molecular mechanism.

METHODS

Neuro-2A cells were exposed to tert-butyl hydroperoxide, a consistent in vitro model of neuronal damage caused by oxidative stress. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, acridine orange/ethidium bromide (AO-EtBr) staining, and phase-view examinations were utilized to evaluate cell survival and cytotoxicity. Real-time reverse transcription-polymerase chain reaction (RT-PCR)-based gene expression studies were conducted.

KEY FINDING

Observations revealed that these two medications had modest but considerable neuroprotective effects. While the majority of the genes' expressions remained unchanged, cerebrolysin upregulated Neuregulin 1, and both upregulated brain-derived neurotrophic factor (BDNF) expression.

CONCLUSION

The findings of the current study may be the first to suggest that citicoline and cerebrolysin may increase host cells' defense mechanisms (secretion neurotrophic factors) rather than carrying nutrients for cell survival. Because of its simplicity, the current study can readily be repeated to learn more about these two disputed medications for treating ischemic stroke.

Getting into the brain: liposome-based strategies for effective drug delivery across the blood-brain barrier

This review summarizes articles that have been reported in literature on liposome-based strategies for effective drug delivery across the blood–brain barrier. Due to their unique physicochemical characteristics, liposomes have been widely investigated for their application in drug delivery and in vivo bioimaging for the treatment and/or diagnosis of neurological diseases, such as Alzheimer’s, Parkinson’s, stroke, and glioma. Several strategies have been used to deliver drug and/or imaging agents to the brain. Covalent ligation of such macromolecules as peptides, antibodies, and RNA aptamers is an effective method for receptor-targeting liposomes, which allows their blood–brain barrier penetration and/or the delivery of their therapeutic molecule specifically to the disease site. Additionally, methods have been employed for the development of liposomes that can respond to external stimuli. It can be concluded that the development of liposomes for brain delivery is still in its infancy, although these systems have the potential to revolutionize the ways in which medicine is administered.

Mitochondrial function in hypoxic ischemic injury and influence of aging

Mitochondria are a major target in hypoxic/ischemic injury. Mitochondrial impairment increases with age leading to dysregulation of molecular pathways linked to mitochondria. The perturbation of mitochondrial homeostasis and cellular energetics worsens outcome following hypoxic-ischemic insults in elderly individuals. In response to acute injury conditions, cellular machinery relies on rapid adaptations by modulating posttranslational modifications. Therefore, post-translational regulation of molecular mediators such as hypoxia-inducible factor 1α (HIF-1α), peroxisome proliferator-activated receptor γ coactivator α (PGC-1α), c-MYC, SIRT1 and AMPK play a critical role in the control of the glycolytic-mitochondrial energy axis in response to hypoxic-ischemic conditions. The deficiency of oxygen and nutrients leads to decreased energetic reliance on mitochondria, promoting glycolysis. The combination of pseudohypoxia, declining autophagy, and dysregulation of stress responses with aging adds to impaired host response to hypoxic-ischemic injury. Furthermore, intermitochondrial signal propagation and tissue wide oscillations in mitochondrial metabolism in response to oxidative stress are emerging as vital to cellular energetics. Recently reported intercellular transport of mitochondria through tunneling nanotubes also play a role in the response to and treatments for ischemic injury. In this review we attempt to provide an overview of some of the molecular mechanisms and potential therapies involved in the alteration of cellular energetics with aging and injury with a neurobiological perspective.

Localized delivery of low-density lipoprotein docosahexaenoic acid nanoparticles to the rat brain using focused ultrasound

Focused ultrasound exposures in the presence of microbubbles can achieve transient, non-invasive, and localized blood-brain barrier (BBB) opening, offering a method for targeted delivery of therapeutic agents into the brain. Low-density lipoprotein (LDL) nanoparticles reconstituted with docosahexaenoic acid (DHA) could have significant therapeutic value in the brain, since DHA is known to be neuroprotective. BBB opening was achieved using pulsed ultrasound exposures in a localized brain region in normal rats, after which LDL nanoparticles containing the fluorescent probe DiR (1,1'-Dioctadecyl-3,3,3',3'-Tetramethylindotricarbocyanine Iodide) or DHA were administered intravenously. Fluorescent imaging of brain tissue from rats administered LDL-DiR demonstrated strong localization of fluorescence signal in the exposed hemisphere. LDL-DHA administration produced 2 × more DHA in the exposed region of the brain, with a corresponding increase in Resolvin D1 levels, indicating DHA was incorporated into cells and metabolized. Histological evaluation did not indicate any evidence of increased tissue damage in exposed brain regions compared to normal brain. This work demonstrates that localized delivery of DHA to the brain is possible using systemically-administered LDL nanoparticles combined with pulsed focused ultrasound exposures in the brain. This technology could be used in regions of acute brain injury or as a means to target infiltrating tumor cells in the brain.

Neuroprotective properties of citicoline: facts, doubts and unresolved issues

Citicoline is the generic name of the pharmaceutical substance that chemically is cytidine-5'-diphosphocholine (CDP-choline), which is identical to the natural intracellular precursor of phospholipid phosphatidylcholine. Following injection or ingestion, citicoline is believed to undergo quick hydrolysis and dephosphorylation to yield cytidine and choline, which then enter the brain separately and are used to resynthesize CDP-choline inside brain cells. Neuroprotective activity of citicoline has been repeatedly shown in preclinical models of brain ischaemia and trauma, but two recent, large, pivotal clinical trials have revealed no benefits in ischaemic stroke and traumatic brain injury. However, the substance seems to be beneficial in some slowly advancing neurodegenerative disorders such as glaucoma and mild vascular cognitive impairment. This paper critically discusses issues related to the clinical pharmacology of citicoline, including its pharmacokinetics/biotransformation and pharmacodynamics/mode of action. It is concluded that at present, there is no adequate description of the mechanism(s) of the pharmacological actions of this substance. The possibility should be considered and tested that, in spite of apparently fast catabolism, the intact citicoline molecule or the phosphorylated intermediate products of its hydrolysis, cytidine monophosphate and phosphocholine, are pharmacologically active.

Liposomes and nanotechnology in drug development: focus on neurological targets

Neurological diseases represent a medical, social, and economic problem of paramount importance in developed countries. Although their etiology is generally known, developing therapeutic interventions for the central nervous system is challenging due to the impermeability of the blood-brain barrier. Thus, the fight against neurological diseases usually struggles "at the gates" of the brain. Flooding the bloodstream with drugs, where only a minor fraction reaches its target therapeutic site, is an inefficient, expensive, and dangerous procedure, because of the risk of side effects at nontargeted sites. Currently, advances in the field of nanotechnology have enabled development of a generation of multifunctional molecular platforms that are capable of transporting drugs across the blood-brain barrier, targeting specific cell types or functional states within the brain, releasing drugs in a controlled manner, and enabling visualization of processes in vivo using conventional imaging systems. The marriage between drug delivery and molecular imaging disciplines has resulted in a relatively new discipline, known as theranostics, which represents the basis of the concept of personalized medicine. In this study, we review the concepts of the blood-brain barrier and the strategies used to traverse/bypass it, the role of nanotechnology in theranostics, the wide range of nanoparticles (with emphasis on liposomes) that can be used as stealth drug carriers, imaging probes and targeting devices for the treatment of neurological diseases, and the targets and targeting strategies envisaged in the treatment of different types of brain pathology.

Vesicular antioxidants: role in age-related cerebral oxidative injury

Oxidative stress, due to the generation of reactive oxygen species, is a major factor in cerebral ischemic damage and changes the activities of antioxidant enzymes and substantially influences the aging process. Free chemical antioxidant is almost ineffective to treat brain ischemia as blood-brain barrier exists in between blood and brain interstitial fluid, limiting component to pass from the circulation into cerebral region. Different compounds have been tested in vivo in different vesiculated forms to prevent cerebral ischemia. Nanoparticle-encapsulated drug treatment resulted in a significant protection of the antioxidant enzymes in both young and old rats. Nanocapsulated drug treatment causes a substantial protection against cerebral ischemia-reperfusion-induced oxidative damage to all parts of brain specifically hippocampal regions of all age groups of rat brain.

Intraperitoneal administration of CDP-choline or a combination of cytidine plus choline improves nerve regeneration and functional recovery in a rat model of sciatic nerve injury

OBJECTIVE

Topical cytidine-5'-diphosphocholine (CDP-choline) improves functional recovery and promotes nerve regeneration in sciatic nerve injury in rats. The aims of this study were to test whether systemic treatment with CDP-choline was effective in improving the recovery of injured sciatic nerve, and to determine whether the cytidine and/or choline moieties of CDP-choline contribute to its beneficial actions.

METHODS

Seventy Sprague-Dawley rats underwent a surgical procedure that involved transectioning and immediate surgical repairing of the right sciatic nerve. Rats were assigned to one of five groups and administered intraperitoneally 1 ml/kg of saline (control) or saline containing 600 μmol/kg of each of CDP-choline, cytidine, choline, or cytidine+choline.

RESULTS

Recovery in sciatic function index score was greater in rats treated with CDP-choline, choline, or cytidine+choline at 8 and 12 weeks after the interventions. Peripheral nerve regeneration evaluated by electromyography at 12 weeks was also greater in rats receiving CDP-choline (228% of control), choline (168% of control), or cytidine+choline (221% of control). Axon counts and axon density increased significantly following CDP-choline, choline, or cytidine+choline, respectively. Treatment with equivalent dose of cytidine failed to affect sciatic function index, electromyography, and axon counts. Treatment with CDP-choline, but not its metabolites improved nerve adherence and separability score.

CONCLUSION

These data show that intraperitoneal CDP-choline, as well as the combination of its metabolites, cytidine+choline, improves functional recovery and promotes regeneration of injured sciatic nerves in rats. CDP-choline also improves nerve adherence and separability.

Mannosylated liposomal cytidine 5' diphosphocholine prevent age related global moderate cerebral ischemia reperfusion induced mitochondrial cytochrome c release in aged rat brain

Mitochondrial dysfunctions generating from cerebral ischemia-reperfusion exert a potential threat on neuronal cell survival and hence, accelerate the aging process and age dependent neuropathology. Thirty min moderate cerebral ischemia induced by bilateral common carotid artery occlusion (BCCAO) followed by 30 min reperfusion caused an increased diene production, depleted glutathione (GSH) content, reduced superoxide dismutase (SOD) and catalase activities and pyramidal neuronal loss in young (2 months old) and aged (20 months old) rat brain compared to sham operated controls. Cytidine 5' diphosphocholine (CDP-Choline) is a known neuroprotective drug. CDP-Choline after metabolism in the liver suffers hydrolysis and splits into cytidine and choline before entering systemic circulation and hardly circumvents blood brain barrier (BBB) as such. Previous reports show CDP-Choline liposomes significantly increased in vivo uptake compared to "free drug" administration in cerebral ischemia. To enhance the therapeutic concentration build up in brain we sought to formulate mannosylated liposomal CDP-Choline (MLCDP) utilizing the mannose receptors. We tested the therapeutic supremacy of MLCDP over liposomal CDP-Choline (LCDP) in global moderate cerebral ischemia reperfusion induced neuronal damage. CDP-Choline in MLCDP delivery system was found potent to exert substantial protection against global moderate cerebral ischemia reperfusion induced mitochondrial damage in aged rat brain. Membrane lipid peroxidation, GSSG/GSH ratio and reactive oxygen species (ROS) generation in cerebral tissue were found to be higher in aged, compared to young rat. Further decline of those parameters was observed in aged rat brain by the induction of global moderate cerebral ischemia and reperfusion. MLCDP treatment when compared to free or LCDP treatment prevented global moderate cerebral ischemia-reperfusion induced mitochondrial damage as evident ultra structurally and release of cytochrome c (cyt c) from mitochondria into cytosol and protected mitochondria to restore its normal structure and functions.

Citicoline improves functional recovery, promotes nerve regeneration, and reduces postoperative scarring after peripheral nerve surgery in rats

BACKGROUND

Citicoline has been shown to have beneficial effects in a variety of CNS injury models. The aim of this study was to test the effects of citicoline on nerve regeneration and scarring in a rat model of peripheral nerve surgery.

METHODS

Seventy adult Sprague-Dawley rats underwent a surgical procedure involving right sciatic nerve section and epineural suturing. Rats were assigned to the control or experiment groups to receive a topical application of 0.4 mL of saline or 0.4 mL (100 micromol/L) of citicoline, respectively. Macroscopic, histological, functional, and electromyographic assessments of nerves were performed 4 to 12 weeks after surgery.

RESULTS

In the control versus citicoline-treated rats, SFI was -90 +/- 1 versus -84 +/- 1 (P < .001), -76 +/- 4 versus -61 +/- 3 (P < .001), and -66 +/- 2 versus -46 +/- 3 (P < .001) at 4, 8, and 12 weeks after surgery, respectively. At 12 weeks after surgery, axon count and diameter were 16400 +/- 600 number/mm(2) and 5.47 +/- 0.25 microm versus 22250 +/- 660 number/mm(2) (P < .001) and 6.65 +/- 0.28 microm (P < .01) in the control and citicoline-treated groups, respectively. In citicoline-treated rats, histomorphological axonal organization score at the repair site was (3.4 +/- 0.1) significantly better than that in controls (2.6 +/- 0.3) (P < .001). Peripheral nerve regeneration evaluated by EMG at 12 weeks after surgery showed significantly better results in the citicoline group (P < .05). Nerves treated with citicoline demonstrated reduced scarring at the repair site (P < .001).

CONCLUSION

Our results demonstrate that citicoline promotes regeneration of peripheral nerves subjected to immediate section suturing type surgery and reduces postoperative scarring.

Citicoline and lithium rescue retinal ganglion cells following partial optic nerve crush in the rat

Citicoline and lithium (Li(-)) have been shown to support retinal ganglion cell (RGC) survival and axon regeneration in vitro. Optic nerve crush (ONC) is a model of both brain axonal injury and certain aspects of the glaucomatous degeneration of RGC. We have used this model to quantify protection offered to RGC by these drugs and to determine whether their effects are mediated by enhanced expression of the antiapoptotic protein Bcl-2. Adult rats (6-12 per group) were subjected to ONC accompanied by a contralateral sham operation. Animals were treated intraperitoneally with either vehicle, citicoline sodium (1g/kg daily for up to 7 days and 300 mg/kg daily afterwards), lithium chloride (30 mg/kg daily), or both drugs combined. Fluorogold was injected bilaterally into superior colliculi 1, 5 or 19 days after ONC. Labeled cells were counted under a fluorescence microscope 2 days after tracer injection. In a separate set of experiments the effects of treatments on expression of Bcl-2 in retinas were evaluated by immunohistochemistry. In vehicle-treated animals there was a progressive decrease of RGC density after crush. This decrease was attenuated in citicoline-treated animals 1 week and 3 weeks after the crush. In the lithium-treated group protection was even more pronounced. In animals treated with both drugs RGC protection was similar to that achieved by lithium alone. Bcl-2 immunoreactivity was seen predominantly in retinal ganglion cells. Its increase was recorded in the lithium and citicoline group as well as in animals treated with the combination of both drugs. Both citicoline and lithium protect RGC and their axons in vivo against delayed degeneration triggered by the ONC. Retinoprotective action of both drugs may involve an increase in Bcl-2 expression.

Radioprotective effect of transferrin targeted citicoline liposomes

The high level of expression of transferrin receptors (Tf-R) on the surface of endothelial cells of the blood-brain-barrier (BBB) had been widely utilized to deliver drugs to the brain. The primary aim of this study was to use transferrin receptor mediated endocytosis as a pathway for the rational development of holo-transferrin coupled liposomes for drug targeting to the brain. Citicoline is a neuroprotective agent used clinically to treat for instance Parkinson disease, stroke, Alzheimer's disease and brain ischemia. Citicoline does not readily cross the BBB because of its strong polar nature. Hence, citicoline was used as a model drug. (Citicoline liposomes have been prepared using dipalmitoylphosphatidylcholine (DPPC) or distearoylphosphatidylcholine (DSPC) by dry lipid film hydration-extrusion method). The effect of the use of liposomes composed of DPPC or DSPC on their citicoline encapsulation efficiency and their stability in vitro were studied. Transferrin was coupled to liposomes by a technique which involves the prevention of scavenging diferric iron atoms of transferrin. The coupling efficiency of transferrin to the liposomes was studied. In vitro evaluation of transferrin-coupled liposomes was performed for their radioprotective effect in radiation treated cell cultures. In this study, OVCAR-3 cells were used as a model cell type over-expressing the Tf-R and human umbilical vein endothelial cells (HUVEC) as BBB endothelial cell model. The average diameter of DPPC and DSPC liposomes were 138 +/- 6.3 and 79.0 +/- 3.2 nm, respectively. The citicoline encapsulation capacity of DPPC and DSPC liposomes was 81.8 +/- 12.8 and 54.9 +/- 0.04 microg/micromol of phospholipid, respectively. Liposomes prepared from DSPC showed relatively better stability than DPPC liposomes at 37 degrees C and in the presence of serum. Hence, DSPC liposomes were used for transferrin coupling and an average of 46-55 molecules of transferrin were present per liposome. Free citicoline has shown radioprotective effect at higher doses tested. Interestingly, encapsulation of citicoline in pegylated liposomes significantly improved the radioprotective effect by 4-fold compared to free citicoline in OVCAR-3 but not in HUVEC. Further, citicoline encapsulation in transferrin-coupled liposomes has significantly improved the radioprotective effect by approximately 8-fold in OVCAR-3 and 2-fold in HUVEC cells with respect to the free drug. This is likely due to the entry of citicoline into cells via transferrin receptor mediated endocytosis. In conclusion, our results suggest that low concentrations of citicoline encapsulated in transferrin-coupled liposomes could offer therapeutic benefit in treating stroke compared to free citicoline.

Mannosylated liposomal flavonoid in combating age-related ischemia–reperfusion induced oxidative damage in rat brain

Active oxygen species alter the activities of the enzymes involved in the defence against free radicals and substantially influence the aging process and age-dependent neuropathology. Unilamellar liposomes were used to deliver flavonoidal antioxidant quercetin (QC) to rat brain. Antioxidant potential of QC loaded in mannosylated (QC 7.2 micromol/kg b.wt.) liposomes (50 nm) was investigated by an in vivo model of cerebral ischemia and reperfusion on Sprague Dawley young (2 months old, b.wt. 160-180 g) and aged (20 months old, b.wt. 415-440 g) rats. Animals were made ischemic for 30 min by bilateral clamping of the common carotid artery followed by a 30 min cerebral reperfusion by withdrawing the clamping. Diene level and (GSSG/GSH) ratio were found to be higher in normal aged, compared to normal young rat brain. Superoxide dismutase, catalase, glucose-6-phosphate dehydrogenase, glutathione reductase and glutathione S-transferase activities were lower in normal aged rat brain. Further reduction of these antioxidant enzymes was observed in aged rat brain by the induction of cerebral ischemia and reperfusion. Mannosylated liposomally encapsulated QC treatment resulted in a significant preservation of the activities of antioxidant enzymes and a marked inhibition of cellular edema formation in neuronal cells of young and old rats.

Tolerability and improved protective action of idebenone-loaded pegylated liposomes on ethanol-induced injury in primary cortical astrocytes

The potential therapeutic advantages of the encapsulation of idebenone within pegylated liposomes were investigated in vitro on primary cortical astrocytes of rats. In particular, both the concentration-dependent effects and the therapeutic effectiveness toward excitotoxic injury, elicited by chronic treatment with ethanol (100 microM) for 12 days, were evaluated. The following parameters were taken into consideration to assay free or liposomally entrapped idebenone: lactic dehydrogenase release, respiratory capacity measured by tetrazolium salt conversion, glutamine synthetase, and the levels of constitutive and inducible 70-kDa heat shock proteins. To evaluate the effects on astrocytes, three different drug concentrations were used (0.5 microM, 5 microM, and 50 microM). At the highest concentration used (50 microM), a toxic effect of the free and liposomally entrapped drug was observed. Toxic effects seem to be due to a cellular membrane perturbation, as demonstrated by (45)Ca(2+) permeation. The therapeutic effect of free or liposomally entrapped idebenone on ethanol-induced injury of primary cortical astrocytes was evaluated as a function of the drug concentration. The drug liposome formulation was much more effective than the free drug in counteracting the ethanol-induced damage in astrocytes, i.e., 10-times-lower doses of liposomally entrapped idebenone are able to provide a greater protective action than the free drug. The improved action of idebenone-loaded liposomes is probably due to the greater drug bioavailability at the cellular level.

PLA(2) dependence of diaphragm mitochondrial formation of reactive oxygen species

Contraction-induced respiratory muscle fatigue and sepsis-related reductions in respiratory muscle force-generating capacity are mediated, at least in part, by reactive oxygen species (ROS). The subcellular sources and mechanisms of generation of ROS in these conditions are incompletely understood. We postulated that the physiological changes associated with muscle contraction (i.e., increases in calcium and ADP concentration) stimulate mitochondrial generation of ROS by a phospholipase A(2) (PLA(2))-modulated process and that sepsis enhances muscle generation of ROS by upregulating PLA(2) activity. To test these hypotheses, we examined H(2)O(2) generation by diaphragm mitochondria isolated from saline-treated control and endotoxin-treated septic animals in the presence and absence of calcium and ADP; we also assessed the effect of PLA(2) inhibitors on H(2)O(2) formation. We found that 1) calcium and ADP stimulated H(2)O(2) formation by diaphragm mitochondria from both control and septic animals; 2) mitochondria from septic animals demonstrated substantially higher H(2)O(2) formation than mitochondria from control animals under basal, calcium-stimulated, and ADP-stimulated conditions; and 3) inhibitors of 14-kDa PLA(2) blocked the enhanced H(2)O(2) generation in all conditions. We also found that administration of arachidonic acid (the principal metabolic product of PLA(2) activation) increased mitochondrial H(2)O(2) formation by interacting with complex I of the electron transport chain. These data suggest that diaphragm mitochondrial ROS formation during contraction and sepsis may be critically dependent on PLA(2) activation.

Evaluating the efficacy of citicoline in embolic ischemic stroke in rats: neuroprotective effects when used alone or in combination with urokinase

The combination of thrombolysis with neuroprotection, because of different mechanisms, would be expected to show better results when used after onset of focal ischemia. In this study we report our experience with the neuronal protective effects of citicoline alone and in combination with urokinase in a model of focal ischemia. Both medications were injected 2 h after onset of a focal occlusion of the middle cerebral artery (MCA) in rats. Focal ischemia was produced with embolization of a clot into the origin of the MCA. This produces a large infarction involving the cortex and the basal ganglia. Animals were observed for neuronal deficts at 2 and 24 h after surgery and were sacrificed 72 h after onset of ischemia. Saline-treated animals showed a large infarction involving the cerebral cortex and basal ganglion in most animals (volume 33.1 +/- 9.7%). Animals treated with citicoline alone were divided in two groups. The first group of animals were treated with a single injection (300 mg/kg, ip) of the medication 2 h after the arterial occlusion. The second group was treated with the active medication intermittently (3 x 300 mg/kg, ip) over a 72-h period. There was a significant decrease in the neuronal damage in the cortex in the animals treated with citicoline (single dose, 20.9 +/- 9.7%, P = 0.01; intermittent injection, 18.9 +/- 11.4%, P < 0.008). The last experiment evaluated the usefulness of the combination of citicoline with intraarterial urokinase. The combination showed significantly more protection than with urokinase or citicoline alone (volume 13.6 +/- 9.1%, P < 0.001). We conclude from our experiments that citicoline may offer significant neuronal protection that may be further enhanced with the addition of a thrombolytic agent.

Reduction of maturation phenomenon in cerebral ischemia with CDP-choline-loaded liposomes

PURPOSE

Cerebral ischemia represents a serious therapeutic challenge. We investigated the therapeutic efficacy of CDP-choline-loaded liposomes against cerebral ischemia. The determination of post-ischemic brain recovery by EEG analysis was carried out to evaluate the effect of CDP-choline-loaded liposomes with respect to the free drug on the maturation of ischemic injury.

METHODS

Long-circulating unilamellar liposomes were prepared by a freeze and thaw procedure followed by an extrusion through polycarbonate membranes. Wistar rats were ischemized by bilateral clamping of the common carotid arteries. Free or liposomally entrapped drug was administered (20 mg/kg) just after ischemia and thereafter once a day for six days. Post-ischemic survival, neuronal membrane peroxidation and brain recovery (EEG analysis) were evaluated.

RESULTS

The post-ischemic reperfused rats treated with CDP-choline-loaded liposomes showed a higher survival rate than animals treated with the free drug. The delayed cerebral neurodegenerative injury due to an ischemic event, referred to as maturation phenomenon, was substantially reduced with the administration of the liposomal formulation. The liposomal carrier showed a marked protection against lipoperoxidative damage.

CONCLUSIONS

Liposomes ensured a rapid recovery of the damaged membranous structure of the neuronal cells, allowing a significant improvement of brain functionality. The reduction of the maturation phenomenon may probably be of particular importance in humans, where a fundamental problem is the quality of life after an ischemic event.