Herbert Moessler

Cerebrolysin decreases amyloid-β production by regulating amyloid protein precursor maturation in a transgenic model of Alzheimer's disease

Cerebrolysin is a peptide mixture with neurotrophic effects that might reduce the neurodegenerative pathology in Alzheimers disease (AD). We have previously shown in an amyloid protein precursor (APP) transgenic (tg) mouse model of AD‐like neuropathology that Cerebrolysin ameliorates behavioral deficits, is neuroprotective, and decreases amyloid burden; however, the mechanisms involved are not completely clear. Cerebrolysin might reduce amyloid deposition by regulating amyloid‐β (Aβ) degradation or by modulating APP expression, maturation, or processing. To investigate these possibilities, APP tg mice were treated for 6 months with Cerebrolysin and analyzed in the water maze, followed by RNA, immunoblot, and confocal microscopy analysis of full‐length (FL) APP and its fragments, β‐secretase (BACE1), and Aβ‐degrading enzymes [neprilysin (Nep) and insulin‐degrading enzyme (IDE)]. Consistent with previous studies, Cerebrolysin ameliorated the performance deficits in the spatial learning portion of the water maze and reduced the synaptic pathology and amyloid burden in the brains of APP tg mice. These effects were associated with reduced levels of FL APP and APP C‐terminal fragments, but levels of BACE1, Notch1, Nep, and IDE were unchanged. In contrast, levels of active cyclin‐dependent kinase‐5 (CDK5) and glycogen synthase kinase‐3β [GSK‐3β; but not stress‐activated protein kinase‐1 (SAPK1)], kinases that phosphorylate APP, were reduced. Furthermore, Cerebrolysin reduced the levels of phosphorylated APP and the accumulation of APP in the neuritic processes. Taken together, these results suggest that Cerebrolysin might reduce AD‐like pathology in the APP tg mice by regulating APP maturation and transport to sites where Aβ protein is generated. This study clarifies the mechanisms through which Cerebrolysin might reduce Aβ production and deposition in AD and further supports the importance of this compound in the potential treatment of early AD.

The neuroprotective effects of Cerebrolysin in a transgenic model of Alzheimer's disease are associated with improved behavioral performance.

Summary. Cerebrolysin™ is a peptide mixture with neurotrophic effects that might have the ability of both reducing amyloid burden and improving synaptic plasticity in Alzheimer’s disease (AD). In order to determine if Cerebrolysin is capable of ameliorating the neurodegenerative and behavioral alterations associated with amyloid β (Aβ) production; transgenic (tg) mice expressing mutant human amyloid precursor protein (APP) under the Thy1 promoter were treated with Cerebrolysin or saline alone starting at 3 or 6 months of age for a total of three months. Animals were then tested behaviorally (at 6 and 9 months of age respectively) in the water maze and then analyzed neuropathologically for amyloid burden, synaptic density, astrogliosis and apoptosis. Performance analysis in the water maze showed that in the younger tg mice cohort, Cerebrolysin treatment significantly ameliorated the performance deficits. In the older cohort, there was a trend toward improved performance in the learning curve. Neuropathological examination showed that in both age/treatment groups, Cerebrolysin promoted synaptic regeneration, and reduced the proportion of neurons displaying DNA fragmentation by the (TdT)-mediated dUTP-biotin nick-end labeling (TUNEL) method. Moreover, Cerebrolysin treatment reduced Aβ burden by 43% in the young group and by 27% in the older group. Taken together, these results suggest that Cerebrolysin treatment might have beneficial effects in patients with cognitive impairment by reducing Aβ accumulation and promoting the preservation of synaptic terminals.

Cerebrolysin modulates pronerve growth factor/nerve growth factor ratio and ameliorates the cholinergic deficit in a transgenic model of Alzheimer's disease

Alzheimers disease (AD) is characterized by degeneration of neocortex, limbic system, and basal forebrain, accompanied by accumulation of amyloid‐β and tangle formation. Cerebrolysin (CBL), a peptide mixture with neurotrophic‐like effects, is reported to improve cognition and activities of daily living in patients with AD. Likewise, CBL reduces synaptic and behavioral deficits in transgenic (tg) mice overexpressing the human amyloid precursor protein (hAPP). The neuroprotective effects of CBL may involve multiple mechanisms, including signaling regulation, control of APP metabolism, and expression of neurotrophic factors. We investigate the effects of CBL in the hAPP tg model of AD on levels of neurotrophic factors, including pro‐nerve growth factor (NGF), NGF, brain‐derived neurotrophic factor (BDNF), neurotropin (NT)‐3, NT4, and ciliary neurotrophic factor (CNTF). Immunoblot analysis demonstrated that levels of pro‐NGF were increased in saline‐treated hAPP tg mice. In contrast, CBL‐treated hAPP tg mice showed levels of pro‐NGF comparable to control and increased levels of mature NGF. Consistently with these results, immunohistochemical analysis demonstrated increased NGF immunoreactivity in the hippocampus of CBL‐treated hAPP tg mice. Protein levels of other neurotrophic factors, including BDNF, NT3, NT4, and CNTF, were unchanged. mRNA levels of NGF and other neurotrophins were also unchanged. Analysis of neurotrophin receptors showed preservation of the levels of TrKA and p75NTR immunoreactivity per cell in the nucleus basalis. Cholinergic cells in the nucleus basalis were reduced in the saline‐treated hAPP tg mice, and treatment with CBL reduced these cholinergic deficits. These results suggest that the neurotrophic effects of CBL might involve modulation of the pro‐NGF/NGF balance and a concomitant protection of cholinergic neurons.

Amelioration of the cerebrovascular amyloidosis in a transgenic model of Alzheimer's disease with the neurotrophic compound cerebrolysin.

Summary.Increased production and reduced clearance of amyloid β (Aβ) plays a central role in the pathogenesis of Alzheimer’s disease (AD). We have recently shown that the neurotrophic peptide mixture Cerebrolysin™ (Cbl) has the ability of improving synaptic functioning and reducing amyloid deposition in a transgenic (tg) animal model of Alzheimer’s disease (AD). Since in AD, potentially toxic Aβ aggregates accumulate not only around neurons but also in the blood vessels, then it is important to investigate whether bioactive compounds such as Cbl might have the capacity to ameliorate the age-related cerebral amyloid angiopathy (CAA) in tg models. To this end, tg mice expressing mutant human amyloid precursor protein (APP) under the Thy1 promoter were treated with Cbl or saline alone starting at 7 or 12 months of age for a total of three months. Neuropathological analysis with an antibody against Aβ showed that Cbl decreased amyloid deposition around the blood vessels in a time dependant manner. These effects were accompanied by a reduction in perivascular microgliosis and astrogliosis and increased expression of markers of vascular fitness such as CD31 and ZO-1. No lymphocytic infiltration was observed associated with Aβ in the vessels. Consistent with these findings, ultrastructural analysis showed that while in tg mice treated with saline alone there was an abundant accumulation of amyloid fibers in the vascular wall accompanied by thickening of the basal membrane and endothelial cell damage, in Cbl-treated mice there was considerable reduction in the subcellular alterations of endothelial and smooth muscle cells with preservation of basal membranes and intercellular junctions. Taken together, these results suggest that Cbl treatment might have beneficial effects in patients with cognitive impairment due to cerebrovascular amyloidosis by reducing Aβ accumulation and promoting the preservation of the cerebrovasculature.

Cerebrolysin in Vascular Dementia: Improvement of Clinical Outcome in a Randomized, Double-Blind, Placebo-Controlled Multicenter Trial

No drug to treat vascular dementia (VaD) has yet been approved by the American or European authorities, leaving a large population of patients without effective therapy. Cerebrolysin has a long record of safety and might be efficacious in this condition. We conducted a large, multicenter, double-blind, placebo-controlled study in 242 patients meeting the criteria for VaD. The primary endpoint was the combined outcome of cognition (based on Alzheimers Disease Assessment Scale Cognitive Subpart, Extended Version [ADAS-cog+] score) and overall clinical functioning (based on Clinicians Interview-Based Impression of Change plus Caregiver Input [CIBIC+] score) assessed after 24 weeks of treatment. Intravenous Cerebrolysin 20 mL was administered once daily over the course of 2 treatment cycles as add-on therapy to basic treatment with acetylsalicylic acid. The addition of Cerebrolysin was associated with significant improvement in both primary parameters. At week 24, ADAS-cog+ score improved by 10.6 points in the Cerebrolysin group, compared with 4.4 points in the placebo group (least squares mean difference, -6.17; P < .0001 vs placebo). CIBIC+ showed a mean improvement of 2.84 in the treatment arm and 3.68 in the placebo arm, a treatment difference of 0.84 (P < .0001 vs placebo). These findings were confirmed by responder analyses demonstrating higher rates in the Cerebrolysin group (ADAS-cog+ improvement of ≥4 points from baseline, 82.1% vs 52.2%; CIBIC+ score of <4 at week 24, 75.3% vs 37.4%; combined response in ADAS-cog+ and CIBIC+, 67.5% vs 27.0%). For Cerebrolysin, the odds ratio for achieving a favorable CIBIC+ response was 5.08 (P < .05), and that for achieving a favorable combined response was 5.63 (P < .05). Our data indicate that the addition of Cerebrolysin significantly improved clinical outcome, and that the benefits persisted for at least 24 weeks. Cerebrolysin was safe and well tolerated.

A pilot study to evaluate the effects of Cerebrolysin on cognition and qEEG in vascular dementia: cognitive improvement correlates with qEEG acceleration.

The effects of the neurotrophic compound Cerebrolysin (Cere) on cognitive performance, evaluated with the ADAS-cog, and on qEEG activity were investigated in forty one patients with mild to moderate severe probable vascular dementia (VaD) according to NINDS-AIREN criteria, included in a placebo-controlled pilot study. Patients received i.v. infusions of Cere (10 or 30 ml) or placebo (normal saline) 5 days/week for 4 weeks. Mean score of change from baseline in the ADAS-cog and percent change from baseline in slow to fast EEG power ratio (PR) scores were the two primary endpoints. Correlations between cognition and qEEG were also evaluated for both baseline scores and for scores of change from baseline in ADAS-cog and in qEEG parameters, including EEG power ratio (PR) as an index of EEG slowing. Baseline ADAS-cog scores showed significant positive correlations with delta power, theta power and PR scores, and correlated negatively with alpha activity. These correlations indicating that an increased EEG slowing is associated with a worst cognitive performance in VaD patients. Cere treatment improved cognitive performance significantly at the 10 ml dose and reduced EEG slowing with both 10 and 30 ml dosages. A significant positive correlation between PR and ADAS-cog scores of change from baseline was observed in Cere-treated patients. According to results of this pilot study, it is concluded that Cere improves cognitive performance and reduces EEG slowing in patients with VaD, and that there is a positive relationship between changes in cognition and qEEG activity induced by Cere. The conduction of further regular clinical trials is required to confirm the potential utility of Cere in the treatment of VaD suggested by the present results.

Neuroprotection of Cerebrolysin in tissue culture models of brain ischemia: post lesion application indicates a wide therapeutic window

Summary.All attempts to reduce neuronal damage after acute brain ischemia by the use of neuroprotective compounds have failed to prove efficacy in clinical trials so far. One of the main reasons might be the relatively narrow time window for intervention. In this study 2 different tissue culture models of ischemia, excitotoxic lesion by the use of glutamate and oxygen–glucose deprivation (OGD), were used to investigate the effects of delayed application of Cerebrolysin (Cere) on neuronal survival. This drug consists of low molecular weight peptides with neuroprotective and neurotrophic properties similar to naturally occurring growth factors. After both types of lesion, acute as well as delayed treatment with Cere resulted in a dose dependent and significant rescue of neurons. In the model of excitotoxic cell death significant drug effects were found even when the treatment started with a delay of 96 hours after addition of glutamate. In the OGD model pronounced effects were found after 48 hours delay of treatment, and even after 72 hours a small but significant rescue of neurons was detected. The neuroprotective effects of a single addition of Cerebrolysin to the culture medium resulted in significant protection until end of the experiments which was up to 2 weeks after the initial lesion. A shift of the efficacious dosages from low to high concentrations indicates that most likely active compounds are used up, indicating that multiple dosing might even increase the effect size. In conclusion the results indicate that Cere displays a relatively wide therapeutic time window which might be explained by a combination of acute neuroprotective properties and neurotrophic efficacy.

A peptide preparation protects cells in organotypic brain slices against cell death after glutamate intoxication.

Summary.Cerebrolysin has been shown to have neurotrophic and neuroprotective potential similar to NGF or BDNF. In the present study organotypic brain slices were utilized to determine the neuroprotective effects of Cerebrolysin, in a glutamate lesion paradigm mimicking a key event in ischemia. The study focused on the effects of Cerebrolysin on both necrotic and apoptotic cell death. Two specific DNA intercalating dyes were used to distinguish the type of cell death. The drug effect was evaluated both microscopically and quantitatively before, 24 hours after and then again 8 days after the lesion. Cerebrolysin was added either before and after the lesion or after the lesion only. The most pronounced effect was seen with the drug added both prior to and after the glutamate lesioning. A treatment after the lesion only also counteracted necrosis and apoptosis. The results render the drug relevant for treating acute as well as chronic neurodegenerative diseases.

Cerebrolysin and Recovery After Stroke (CARS): A Randomized, Placebo-Controlled, Double-Blind, Multicenter Trial

Background and Purpose— The aim of this trial was to investigate whether stroke patients who receive Cerebrolysin show improved motor function in the upper extremities at day 90 compared with patients who receive a placebo. Methods— This study was a prospective, randomized, double-blind, placebo-controlled, multicenter, parallel-group study. Patients were treated with Cerebrolysin (30 mL/d) or a placebo (saline) once daily for 21 days, beginning at 24 to 72 hours after stroke onset. The patients also participated in a standardized rehabilitation program for 21 days that was initiated within 72 hours after stroke onset. The primary end point was the Action Research Arm Test score on day 90. Results— The nonparametric effect size on the Action Research Arm Test score on day 90 indicated a large superiority of Cerebrolysin compared with the placebo (Mann–Whitney estimator, 0.71; 95% confidence interval, 0.63–0.79; P<0.0001). The multivariate effect size on global status, as assessed using 12 different outcome scales, indicated a small-to-medium superiority of Cerebrolysin (Mann–Whitney estimator, 0.62; 95% confidence interval, 0.58–0.65; P<0.0001). The rate of premature discontinuation was <5% (3.8%). Cerebrolysin was safe and well tolerated. Conclusions— Cerebrolysin had a beneficial effect on function and global outcome in early rehabilitation patients after stroke. Its safety was comparable with that of the placebo, suggesting a favorable benefit/risk ratio. Because this study was exploratory and had a relatively small sample size, the results should be confirmed in a large-scale, randomized clinical trial. Clinical Trial Registration— URL: http://www.clinicaltrialsregister.eu. Unique identifier: 2007-000870-21.

Apathy and APOE4 are associated with reduced BDNF levels in Alzheimer's disease.

Reduced brain-derived neurotrophic factor (BDNF) signaling is considered as a pathogenic event in early Alzheimers disease (AD), but the influence of apathy and apolipoprotein E ε4 allele (APOE4) on serum BDNF values was not previously investigated in AD. We evaluated serum BDNF levels in AD, amnestic mild cognitive impairment (MCI), and control subjects. Baseline BDNF levels were similar in AD, MCI, and controls. AD patients having apathy showed lower BDNF values than patients without apathy (p < 0.05). After correction for the influence of apathy, APOE4 carriers showed lower BDNF levels (p < 0.01) and MMSE scores (p < 0.01) than non-APOE4 carriers in the subgroup of AD females, but not in males. Significant (p < 0.05) positive correlations between BDNF values and MMSE scores were only observed in subgroups of AD males and of AD patients without apathy. These results are showing the association of apathy and APOE4 with reduced serum BDNF levels in AD, and are suggesting that BDNF reductions might contribute to the worse cognitive performance exhibited by AD apathetic patients and female APOE4 carriers.