Activation of migration of endogenous stem cells by erythropoietin as potential rescue for neurodegenerative diseases.

UNLABELLED: Neurodegenerative disorders such as Alzheimer's disease (AD) are characterized by progressive cognitive dysfunction and memory loss. There is deposition of amyloid plaques in the brain and subsequent neuronal loss. Neuroinflammation plays a key role in the pathogenesis of AD. There is still no effective curative therapy for these patients. One promising strategy involves the stimulation of endogenous stem cells. This study investigated the therapeutic effect of erythropoietin (EPO) in neurogenesis, and proved its manipulation of the endogenous mesenchymal stem cells in model of lipopolysaccharide (LPS)-induced neuroinflammation. METHODS: Forty five adult male mice were divided equally into 3 groups: Group I (control), group II (LPS untreated group): mice were injected with single dose of lipopolysaccharide (LPS) 0.8 mg/kg intraperitoneally (ip) to induce neuroinflammation, group III (EPO treated group): in addition to (LPS) mice were further injected with EPO in dose of 40 µg/kg of body weight three times weekly for 5 consecutive weeks. Groups were tested for their locomotor activity and memory using open field test and Y-maze. Cerebral specimens were subjected to histological and morphometric studies. Glial fibrillary acidic protein (GFAP) and mesenchymal stem cell marker CD44 were assessed using immunostaining. Gene expression of brain derived neurotrophic factor (BDNF) was examined in brain tissue. RESULTS: LPS decreased locomotor activity and percentage of correct choices in Y-maze test. Cerebral sections of LPS treated mice showed increased percentage area of dark nuclei and amyloid plaques. Multiple GFAP positive astrocytes were detected in affected cerebral sections. In addition, decrease BDNF gene expression was noted. On the other hand, EPO treated group, showed improvement in locomotor and cognitive function. Examination of the cerebral sections showed multiple neurons exhibiting less dark nuclei and less amyloid plaques in comparison to the untreated group. GFAP positive astrocytes were also reduced. Cerebral sections of the EPO treated group showed multiple branched and spindle CD44 positive cells inside and around blood vessels more than in LPS group. This immunostaining was negative in the control group. EPO administration increased BDNF gene expression. CONCLUSION: This study proved that EPO provides excellent neuroprotective and neurotrophic effects in vivo model of LPS induced neuroinflammation. It enhances brain tissue regeneration via stimulation of endogenous mesenchymal stem cells proliferation and their migration to the site of inflammation. EPO also up regulates cerebral BDNF expression and production, which might contributes to EPO mediated neurogenesis. It also attenuates reactive gliosis thus reduces neuroinflammation. These encouraging results obtained with the use of EPO proved that it may be a promising candidate for future clinical application and treatment of neurodegenerative diseases.

The hematopoietic growth factor "erythropoietin" enhances the therapeutic effect of mesenchymal stem cells in Alzheimer's disease.

Alzheimer's disease is a neurodegenerative disorder clinically characterized by cognitive dysfunction and by deposition of amyloid plaques, neurofibrillary tangles in the brain. The study investigated the therapeutic effect of combined mesenchymal stem cells and erythropoietin on Alzheimer's disease. Five groups of mice were used: control group, Alzheimer's disease was induced in four groups by a single intraperitoneal injection of 0.8 mg kg(-1) lipopolysaccharide and divided as follows: Alzheimer's disease group, mesenchymal stem cells treated group by injecting mesenchymal stem cells into the tail vein (2 x 10(6) cells), erythropoietin treated group (40 microg kg(-1) b.wt.) injected intraperitoneally 3 times/week for 5 weeks and mesenchymal stem cells and erythropoietin treated group. Locomotor activity and memory were tested using open field and Y-maze. Histological, histochemical, immunohistochemical studies, morphometric measurements were examined in brain sections of all groups. Choline transferase activity, brain derived neurotrophic factor expression and mitochondrial swellings were assessed in cerebral specimens. Lipopolysaccharide decreased locomotor activity, memory, choline transferase activity and brain derived neurotrophic factor. It increased mitochondrial swelling, apoptotic index and amyloid deposition. Combined mesenchymal stem cells and erythropoietin markedly improved all these parameters. This study proved the effective role of mesenchymal stem cells in relieving Alzheimer's disease symptoms and manifestations; it highlighted the important role of erythropoietin in the treatment of Alzheimer's disease.

Mechanisms of vincristine-induced neurotoxicity: Possible reversal by erythropoietin.

Vincristine (VCR) is a potent anticancer drug, but neurotoxicity is one of its most important dose-limiting toxicities. In this study, we investigated the neurotoxic effect of VCR, the possible mechanisms and the role of erythropoietin (EPO) in the protection against VCR-induced neurotoxicity in a rat model. The neurotoxicity of VCR and protective effect of EPO were examined using the tail flick test and by recording electrophysiological characteristics in isolated sciatic nerve. To elucidate the underlying mechanisms, mRNA expression of N-methyl-D-aspartate (NMDA) receptor, an index of glutamate excitotoxicity, and calcitonin gene-related peptide (CGRP), an important regulator of vascular tone, were measured in both spinal cord and sciatic nerves using an RT-PCR method. After intraperitoneal injection at a dose of 150 µg/kg three times weekly for five consecutive weeks, VCR significantly decreased the latency of tail withdrawal reflex, the amplitude of maximum compound action potential (MCAP) and chronaxie, and prolonged the duration of action potential (AP) and relative refractory period (RRP), but it had no effect on conduction velocity. VCR increased NMDA receptor expression and decreased CGRP expression. Forty µg/kg of EPO improved all VCR-induced changes, except chronaxie, while a higher dose of 80 µg/kg reversed all parameters and its effect was more prominent on tail flick test latency and NMDA receptor expression. These results suggested that VCR might cause increased nerve excitability and induce a state of glutamate excitotoxicity through enhancing NMDA receptor expression and diminishing CGRP expression, thus resulting in axonal degeneration. EPO had an obvious neuroprotective effect probably through decreasing NMDA receptor expression and increasing CGRP expression both centrally and peripherally.

Thymoquinone triggers anti-apoptotic signaling targeting death ligand and apoptotic regulators in a model of hepatic ischemia reperfusion injury.

Thymoquinone (TQ) has been reported as a potent inducer of apoptosis in cancer cells. However, the role of TQ as an apoptotic or antiapoptotic has not been established yet in other types of cell injuries. Our objective was to explore whether TQ exerts a hepatoprotective effect against hepatic ischemia reperfusion injury (I/R) and to identify its potential effect on apoptotic pathways. Rats were divided into eight groups: group I: shamoperated; group II: I/R (45 min ischemia-60 min reperfusion). The other six groups were given PO administration of TQ aqueous solution at 5, 20, and 50 mg/kg/day dose levels for 10 days. At the end of treatment three groups were not subjected to any intervention (groups III, IV, and V: TQ control groups) or subjected to 45 min ischemia followed by one-hour reperfusion as in group II (groups VI, VII, and VIII: TQ pretreated I/R groups). Serum levels of liver enzymes, tissue levels of malondialdehyde (MDA), reduced glutathione (GSH) and TNF-α were measured. Activities of caspases 8, 9, and 3 were determined. Cytochrome c in cytosol was determined by solid phase ELISA. Expression of anti-apoptotic Bcl-2 and pro-apoptotic Bax proteins as well as nuclear factor κB (NF-κB) were assessed using polymerase chain reaction. Apoptosis end point was detected using electrophoresis for analysis of DNA fragmentation. TQ administration before I/R resulted in a significant decrease in liver enzymes, MDA and TNF-α tissue levels with increased GSH content. It also inhibited cytochrome c release into the cytosol, down regulated the expression of NF-κB and Bax and up regulated the Bcl-2 proteins. Hepatic apoptosis was significantly attenuated as indicated by a significant decrease in all caspase activities and by DNA fragmentation. In conclusion, TQ exerts an antiapoptotic effect through attenuating oxidative stress and inhibiting TNF-α induced NF-κB activation. Furthermore, it regulates the Bcl-2/Bax ratio and inhibits downstream caspases in this I/R model.

Promising therapy for Alzheimer's disease targeting angiotensinconverting enzyme and the cyclooxygense-2 isoform.

Deposition of ß-amyloid in brain is one of the pathological hallmarks of Alzheimer's disease (AD) that is often associated with inflammatory response. Much evidence also points to a link between the renin-angiotensin system, hypertension and dementia. Accordingly, the potential use of anti-inflammatory and antihypertensives might be beneficial agents in AD therapy. In this study, we investigated the possible mechanisms of Celecoxib (cyclooxygenase-2 (COX-2) inhibitor), Perindopril (angiotensin converting enzyme (ACE) inhibitor) and their combination in a lipopolysaccharide (LPS) model of AD. Mice were injected with LPS (0.8 mg/ kg, i.p.) once then divided into three groups: the first was treated with Celecoxib (30 mg/kg/day, i.p.), the second with Perindopril (0.5 mg/kg/day, i.p.) and the last group with a combination of both drugs. Learning and memory function were tested using a Y-maze and locomotor activity was assessed using an open-field test. Cerebral specimens were subjected to histopathological studies. Brain tumor necrosis factor alpha (TNF-α), and interleukin (IL)-1ß levels were measured. LPS decreased locomotor activity and percentage of correct choices in the Y-maze test. It also produced a significant increase in the percentage area of vascular angiopathy, area of lamellated plaques, and apoptotic index. These were associated with increased TNF-α and IL-1ß. Administration of either Celecoxib or Perindopril partially improved cognitive impairment, decreased inflammatory cytokines and amyloid deposition. Combined therapy of both drugs completely prevented LPS induced neurodegenerative and cognitive changes. In conclusion, these findings establish a link between COX-2, ACE activity and cognitive impairment in AD and provided a promising strategy for the complete cure of AD.