Reham M. Abdel-Kader

Mitochondrial Dysfunction—A Pharmacological Target in Alzheimer's Disease

Increasing evidences suggest that mitochondrial dysfunction plays an important role in the pathogenesis of neurodegenerative diseases including Alzheimers disease (AD). Alterations of mitochondrial efficiency and function are mainly related to alterations in mitochondrial content, amount of respiratory enzymes, or changes in enzyme activities leading to oxidative stress, mitochondrial permeability transition pore opening, and enhanced apoptosis. More recently, structural changes of the network are related to bioenergetic function, and its consequences are a matter of intensive research. Several mitochondria-targeting compounds with potential efficacy in AD including dimebon, methylene blue, piracetam, simvastatin, Ginkgo biloba, curcumin, and omega-3 polyunsaturated fatty acids have been identified. The majority of preclinical data indicate beneficial effects, whereas most controlled clinical trials did not meet the expectations. Since mitochondrial dysfunction represents an early event in disease progression, one reason for the disappointing clinical results could be that pharmacological interventions might came too late. Thus, more studies are needed that focus on therapeutic strategies starting before severe disease progress.

Bcl-2 upregulation and neuroprotection in guinea pig brain following chronic simvastatin treatment.

The present study determined if chronic simvastatin administration in vivo would provide neuroprotection in brain cells isolated from guinea pigs after challenge with the Bcl-2 inhibitor HA 14-1 or the NO donor sodium nitroprusside (SNP). Bcl-2 levels were significantly increased in brains of simvastatin-treated guinea pigs while levels of the pro-apoptotic protein Bax were significantly reduced. The ratio of Bax/Bcl-2, being a critical factor of the apoptotic state of cells, was significantly reduced in simvastatin-treated animals. Cholesterol levels in the brain remained unchanged in the simvastatin group. Brain cells isolated from simvastatin-treated guinea pigs were significantly less vulnerable to mitochondrial dysfunction and caspase-activation. These results provide new insight into potential mechanisms for the protective actions of statins within the CNS where programmed cell death has been implicated.

Curcumin prevents mitochondrial dysfunction in the brain of the senescence-accelerated mouse-prone 8.

The aging brain suffers mitochondrial dysfunction and a reduced availability of energy in the form of ATP, which in turn may cause or promote the decline in cognitive, sensory, and motor function observed with advancing age. There is a need for animal models that display some of the pathological features of human brain aging in order to study their prevention by e.g. dietary factors. We thus investigated the suitability of the fast-aging senescence-accelerated mouse-prone 8 (SAMP8) strain and its normally aging control senescence-accelerated mouse-resistant 1 (SAMR1) as a model for the age-dependent changes in mitochondrial function in the brain. To this end, 2-months old male SAMR1 (n=10) and SAMP8 mice (n=7) were fed a Western type diet (control groups) for 5months and one group of SAMP8 mice (n=6) was fed an identical diet fortified with 500mg curcumin per kg. Dissociated brain cells and brain tissue homogenates were analyzed for malondialdehyde, heme oxygenase-1 mRNA, mitochondrial membrane potential (MMP), ATP concentrations, protein levels of mitochondrial marker proteins for mitochondrial membranes (TIMM, TOMM), the mitochondrial permeability transition pore (ANT1, VDAC1, TSPO), respiration complexes, and fission and fusion (Fis, Opa1, Mfn1, Drp1). Dissociated brain cells isolated from SAMP8 mice showed significantly reduced MMP and ATP levels, probably due to significantly diminished complex V protein expression, and increased expression of TSPO. Fission and fusion marker proteins indicate enhanced mitochondrial fission in brains of SAMP8 mice. Treatment of SAMP8 mice with curcumin improved MMP and ATP and restored mitochondrial fusion, probably by up-regulating nuclear factor PGC1α protein expression. In conclusion, SAMP8 compared to SAMR1 mice are a suitable model to study age-dependent changes in mitochondrial function and curcumin emerges as a promising nutraceutical for the prevention of neurodegenerative diseases that are accompanied or caused by mitochondrial dysfunction.

Methylene Blue Improves Brain Mitochondrial ABAD Functions and Decreases Aβ in a Neuroinflammatory Alzheimer's Disease Mouse Model.

Methylene blue (MB) phase II clinical trials reported improvements in cognitive functions of Alzheimer’s disease (AD) patients. Regarding MB mechanism of action, its antioxidant and mitochondrial protective effects have been previously described. In relation to AD, it has been recently reported that MB reduced amyloid beta (Aβ) levels in AD models. The mitochondrial enzyme amyloid-binding alcohol dehydrogenase (ABAD) has been shown to bind Aβ inducing mitochondrial dysfunction, providing a direct relation between Aβ toxicity and mitochondrial dysfunction occurring in AD. Since it has been reported that inhibiting ABAD protects mitochondrial functions and prevents Aβ-induced toxicity, the aim of the current study was to investigate if the protective effects of MB could be associated with an effect on ABAD levels and functions. The current study shows that MB is able to enhance cell viability, reduce both reactive oxygen species levels and importantly Aβ oligomers in a lipopolysaccharide (LPS) mouse model. Interestingly, ABAD levels were increased in the brains of the LPS mouse model and MB treatment was able to reduce its levels. Given that regulation of the estradiol level is a well-established function of ABAD, brain estradiol level was compared in LPS mouse model and in MB-treated mice. The results of the current study show that MB treatment is able to improve significantly the LPS-induced decrease of estradiol levels in mice brains, indicating its ability to modulate both levels and function of ABAD. These results give a new insight to possible mechanisms of MB in AD.

Targeted penetration of MCF-7 cells using iron-oxide nanoparticles in vitro

We achieve selective penetration of MCF-7 breast cancer cells using iron-oxide nanoparticles without causing a permanent damage to the membrane and without any effect on the cell morphology. The nanoparticles are controllably pulled towards the cells under the influence of the magnetic field gradients. First, the nanoparticles are fabricated and their magnetic dipole moment is characterized to be 7.8×10-8 A.m2, at magnetic field of 60 mT and mass of 1.80×10-9 kg. This characterization is done by measuring the magnetic force exerted on their dipole moment under the influence of controlled magnetic field gradient. Second, a magnetic-based control system is designed and used to achieve selective targeting of the cells under microscopic guidance. We find that the magnetic control achieves immediate uptake of nanoparticles in the MCF-7 cells without incubation for relatively long time, using magnetic force less than 51 nN. In addition, a microforce sensing probe is used to characterize the impendence of the cells to limit the exerted magnetic force during penetration and to avoid causing damage to the membrane. We find that a single cell can overcome penetration force in excess of 13.3 μN.

Targeting of cell mockups using sperm-shaped microrobots in vitro

Sperm-shaped microrobots are controlled under the influence of weak oscillating magnetic fields (milliTesla range) to selectively target cell mockups (i.e., gas bubbles with average diameter of 200 μm). The sperm-shaped microrobots are fabricated by electrospinning using a solution of polystyrene, dimethylformamide, and iron oxide nanoparticles. These nanoparticles are concentrated within the head of the microrobot, and hence enable directional control along external magnetic fields. The magnetic dipole moment of the microrobot is characterized (using the flip-time technique) to be 1.4×10-11 A.m2, at magnetic field of 28 mT. In addition, the morphology of the microrobot is characterized using Scanning Electron Microscopy images. The characterized parameters and morphology are used in the simulation of the locomotion mechanism of the microrobot to prove that its motion depends on breaking the time-reversal symmetry, rather than pulling with the magnetic field gradient. We experimentally demonstrate that the microrobot can controllably follow S-shaped, U-shaped, and square paths, and selectively target the cell mockups using image guidance and under the influence of the oscillating magnetic fields.

Design and implementation of implanted antenna inside a human body

The main objectives of this article is to design a microstrip antenna and discuss the effect of human tissues on its performance. This antenna will help in the future as a brainstorm to build a communication link with implanted devices to increase the capability of diagnosis and/or treatment and reduces the need for invasive surgical operations. It is pivotal to establish a low profile, small, safe and cost effective antenna in order to be utilized inside a realistic human body environment. The paper contains a cardioid patch antennas using microstrip feed. The antennas are simulated using CST microwave studio, fabricated and tested on the network analyzer. It operated from 3.5GHz to 10GHz. Based on simulation and measurement; it shows that the proposed antenna gives efficient agreement. For the investigation of the human tissues on some antenna parameters the rats are used to represent these issues.

Methylene blue decreases brain mitochondrial ABAD and amyloid beta levels protecting mitochondrial functions in LPS-mouse model

Background Methylene blue (MB) is lately being proposed to be effective in treating Alzheimer’s disease (AD). Phase 2 clinical trials reported improvements in cognitive functions of AD patients after MB treatment. One of the main mechanisms of action that has been described for MB is inhibition of Tau aggregation [1]. Moreover, its antioxidant and mitochondrial protection have been previously described [2]. Only recently, a study using a triple transgenic AD mouse model has tested the mechanism of MB in vivo, showing improved cognition and reduced Ab levels after MB treatment [3]. Recently, the mitochondrial enzyme Amyloid binding alcohol dehydrogenase (ABAD) has been shown to bind Ab inducing mitochondrial dysfunction, providing a direct relation between Ab and mitochondrial dysfunction occurring in AD. Previous studies have shown that inhibiting ABAD protects mitochondrial functions and prevented Ab-induced toxicity [4][5]. Taking into consideration the mitochondrial protective effect of MB and the recent data suggesting its ability to reduce Ab levels, our aim was to investigate the effect of MB on ABAD and mitochondrial function in an LPS mouse model that has been previously described to induce memory impairment, with Ab accumulation in hippocampus and cerebral cortex [6].