Blueberry extract enhances survival of intraocular hippocampal transplants

Systematic Review of the Effects of Blueberry on Cognitive Performance as We Age

The effect of flavonoid-rich food, such as blueberries, on cognitive function has been subject to a growing amount of research interest in recent years. Epidemiological, prospective, preclinical, and clinical trials have revealed positive cognitive benefits from flavonoid interventions, particularly in relation to the amelioration of cognitive decline in older adults. This review will specifically consider the existing clinical research from both acute and chronic blueberry interventions on cognition in human subjects. The results of 11 studies are reported with 4 studies considering blueberry intervention with children aged 7-10 years, 4 considering adults aged 60 years and older, and 3 considering adults suffering from mild cognitive impairment (MCI). Findings from these studies indicate that cognitive benefits may be found for delayed memory and executive function in children and for delayed memory, executive function, and psychomotor function in older healthy and MCI adults. There is less evidence to suggest positive benefits of blueberry intervention on working memory. Recommendations for future research, including dose used, cognitive tasks, and age groups considered, are proposed.

Aging leads to altered microglial function that reduces brain resiliency increasing vulnerability to neurodegenerative diseases

Aging is the primary risk factor for many neurodegenerative diseases. Thus, understanding the basic biological changes that take place with aging that lead to the brain being less resilient to disease progression of neurodegenerative diseases such as Parkinson's disease or Alzheimer's disease or insults to the brain such as stroke or traumatic brain injuries. Clearly this will not cure the disease per se, yet increasing the ability of the brain to respond to injury could improve long term outcomes. The focus of this review is examining changes in microglia with age and possible therapeutic interventions involving the use of polyphenol rich dietary supplements.

Nutraceutical intervention reverses the negative effects of blood from aged rats on stem cells

Aging is associated with a decline in function in many of the stem cell niches of the body. An emerging body of literature suggests that one of the reasons for this decline in function is due to cell non-autonomous influences on the niche from the body. For example, studies using the technique of parabiosis have demonstrated a negative influence of blood from aged mice on muscle satellite cells and neurogenesis in young mice. We examined if we could reverse this effect of aged serum on stem cell proliferation by treating aged rats with NT-020, a dietary supplement containing blueberry, green tea, vitamin D3, and carnosine that has been shown to increase neurogenesis in aged rats. Young and aged rats were administered either control NIH-31 diet or one supplemented with NT-020 for 28 days, and serum was collected upon euthanasia. The serum was used in cultures of both rat hippocampal neural progenitor cells (NPCs) and rat bone marrow-derived mesenchymal stem cells (MSCs). Serum from aged rats significantly reduced cell proliferation as measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-bromo-2'-deoxyuridine (BrdU) assays in both NPCs and MSCs. Serum from aged rats treated with NT-020 was not different from serum from young rats. Therefore, NT-020 rescued the effect of serum from aged rats to reduce stem cell proliferation.

Dietary supplementation with blueberry extract improves survival of transplanted dopamine neurons

The exact mechanisms contributing to poor neuronal survival in cell transplantation paradigms for Parkinson's disease (PD) are unknown. However, transplantation-induced host immune response, inflammation, and subsequent oxidative stress are likely contributors to cell death since dopamine (DA) neurons are exquisitely sensitive to oxidative damage. Multiple studies have attempted to improve cell survival by treating transplant material with antioxidant and antiinflammatory compounds, whereas far fewer studies have attempted to modify the host environment to reduce these threats. Flavonoids, phytochemicals found in fruits and vegetables, have antioxidant, antiinflammatory, and immunomodulatory properties. For example, supplementation with dietary blueberry extract (BBE) prevents oxidative stress-associated impairment of striatal motor function during aging and restores lost motor function in aged rats. We hypothesized that dietary supplementation of rodent diets with BBE would improve the survival of embryonic DA neurons transplanted into the unilaterally DA-depleted striatum. Inclusion of 2% BBE in a custom chow diet significantly increased the survival of implanted DA neurons and ameliorated rotational behavior asymmetries as compared to transplanted animals consuming a standard diet. These findings provide support for the potential of dietary phytochemicals as an easily administered and well-tolerated therapy that can be used to improve the effectiveness of DA neuron replacement.

A high-fat/high-cholesterol diet inhibits growth of fetal hippocampal transplants via increased inflammation

A diet containing high levels of saturated fat and cholesterol is detrimental to many aspects of health and is known to lead to obesity, metabolic syndrome, heart disease, diabetes, and cancer. However, the effects of a diet rich in saturated fat and cholesterol on the brain are not currently well understood. In order to determine direct effects of a high saturated fat and cholesterol diet upon fetal hippocampal tissue, we transplanted hippocampal grafts from embryonic day 18 rats to the anterior eye chamber of 16-month-old host animals that were fed either a normal rat chow diet or a 10% hydrogenated coconut oil + 2% cholesterol diet (HFHC diet) for 8 weeks. One eye per rat received topical application of an IL-1 receptor antagonist (IL-1Ra, Kineret®) and the other served as a saline control. Results revealed that the HFHC diet led to a marked reduction in hippocampal transplant growth, and detrimental effects of the diet were alleviated by the IL-1 receptor antagonist IL-1Ra. Graft morphology demonstrated that the HFHC diet reduced organotypical development of the hippocampal neuronal cell layers, which was also alleviated by IL-1Ra. Finally, grafts were evaluated with markers for glucose transporter expression, astrocytes, and activated microglia. Our results demonstrate significant effects of the HFHC diet on hippocampal morphology, including elevated microglial activation and reduced neuronal development. IL-1Ra largely blocked the detrimental effects of this diet, suggesting a potential use for this agent in neurological disorders involving neuroinflammation.

Blueberry supplementation attenuates microglial activation in hippocampal intraocular grafts to aged hosts

Transplantation of central nervous tissue has been proposed as a therapeutic intervention for age-related neurodegenerative diseases and stroke. However, survival of embryonic neuronal cells is hampered by detrimental factors in the aged host brain such as circulating inflammatory cytokines and oxidative stress. We have previously found that supplementation with 2% blueberry in the diet increases graft growth and neuronal survival in intraocular hippocampal grafts to aged hosts. In the present study we explored possible biochemical mechanisms for this increased survival, and we here report decreased microglial activation and astrogliosis in intraocular hippocampal grafts to middle-aged hosts fed a 2% blueberry diet. Markers for astrocytes and for activated microglial cells were both decreased long-term after grafting to blueberry-treated hosts compared with age-matched rats on a control diet. Similar findings were obtained in the host brain, with a reduction in OX-6 immunoreactive microglial cells in the hippocampus of those recipients treated with blueberry. In addition, immunoreactivity for the pro-inflammatory cytokine IL-6 was found to be significantly attenuated in intraocular grafts by the 2% blueberry diet. These studies demonstrate direct effects of blueberry upon microglial activation both during isolated conditions and in the aged host brain and suggest that this nutraceutical can attenuate age-induced inflammation.

Beneficial effects of antioxidant-enriched diet for tyrosine hydroxylase-positive neurons in ventral mesencephalic tissue in oculo grafts

Supplementation of antioxidants to the diet has been proved to be beneficial in aging and after brain injury. Furthermore, it has been postulated that the locus coeruleus promotes survival of dopamine neurons. Thus, this study was performed to elucidate the effects of a blueberry-enriched diet on fetal ventral mesencephalic tissue in the presence or absence of locus coeruleus utilizing the in oculo grafting method. Sprague-Dawley rats were given control diet or diet supplemented with 2% blueberries, and solid tissue pieces of fetal locus coeruleus and ventral mesencephalon were implanted as single and co-grafts. The results revealed that the presence of locus coeruleus tissue or the addition of blueberries enhanced the survival of ventral mesencephalic tyrosine hydroxylase (TH)-positive neurons, whereas no additive effects were observed for the two treatments. The density of TH-positive nerve fibers in ventral mesencephalic tissue was significantly elevated when it was attached to the locus coeruleus or by blueberry treatment, whereas the innervation of dopamine-beta-hydroxylase-positive nerve fibers was not altered. The presence of locus coeruleus tissue or bluberry supplementation reduced the number of Iba-1-positive microglia in the ventral mesencephalic portion of single and co-grafts, respectively, whereas almost no OX6 immunoreactivity was found. Furthermore, neither the attachment of ventral mesencephalic tissue nor the addition of blueberries improved the survival of TH-positive neurons in the locus coerulean grafts. To conclude, locus coeruleus and blueberries are beneficial for the survival of fetal ventral mesencephalic tissue, findings that could be useful when grafting tissue in Parkinson's disease.

Blueberry-enriched diet ameliorates age-related declines in NMDA receptor-dependent LTP

NMDA receptor-dependent long-term potentiation (LTP) in the hippocampus is widely accepted as a cellular substrate for memory formation. Age-related declines in the expression of both NMDAR-dependent LTP and NMDAR subunit proteins in the CA1 region of the hippocampus have been well characterized and likely underlie age-related memory impairment. In the current study, we examined NMDAR-dependent LTP in young Fischer 344 rats (4 months old) and aged rats (24 months old) given either a control diet or a diet supplemented with blueberry extract for 6-8 weeks. NMDAR-dependent LTP was evoked by high-frequency stimulation (HFS) in the presence of nifedipine, to eliminate voltage-gated calcium channel LTP. Field excitatory postsynaptic potentials (fEPSPs) were increased by 57% 1 h after HFS in young animals, but this potentiation was reduced to 31% in aged animals. Supplementation of the diet with blueberry extract elevated LTP (63%) in aged animals to levels seen in young. The normalization of LTP may be due to the blueberry diet preventing a decline in synaptic strength, as measured by the slope of the fEPSP for a given fiber potential. The blueberry diet did not prevent age-related declines in NMDAR protein expression. However, phosphorylation of a key tyrosine residue on the NR2B subunit, important for increasing NMDAR function, was enhanced by the diet, suggesting that an increase in NMDAR function might overcome the loss in protein. This report provides evidence that dietary alterations later in life may prevent or postpone the cognitive declines associated with aging.

Green tea polyphenols affect skin preservation in rats and improve the rate of skin grafts

Green tea polyphenols have been recently reported to promote the preservation of tissues, such as blood vessels, corneas, nerves, islet cells, articular cartilage, and myocardium, at room temperature. These findings indicate the possibility of a new method of tissue banking without freezing. A main active ingredient of green tea, epigallocatechin-3-gallate (EGCG), is a polyphenol that possesses antioxidant, antimicrobial, antiproliferative, and free radical scavenging effects. This study examined the effects of EGCG regarding skin preservation. Skin sample biopsy specimens measuring 1 x 1 cm from GFP rats were held in sterile containers with 50 ml preserving solution at 4 degrees C and 37 degrees C for up to about 8 weeks. Periodically, some of the preserved skin specimens were directly examined histologically and others were transplanted into nude mice. Histological examinations of skin preserved at 4 degrees C revealed a degeneration of the epidermal and dermal layers from 5 weeks in all groups. In the groups preserved at 37 degrees C, degeneration and flakiness of the epidermal layer were demonstrated starting at 2 weeks preservation regardless of addition of EGCG. After 2-7 weeks of preservation the rat skin grafted to nude mice in the EGCG groups stored at 4 degrees C showed successful engraftment. However, grafts preserved at 4 degrees C without EGCG and at 37 degrees C did not demonstrate GFP-positive keratinocyte or fibroblasts. In conclusion, the present findings suggest the future clinical usefulness of EGCG for skin preservation without freezing; however, the mechanism by which EGCG promotes skin preservation still remains unclear.

Dietary oxyresveratrol prevents parkinsonian mimetic 6-hydroxydopamine neurotoxicity

Oxyresveratrol (OXY) is a polyhydroxylated stilbene existing in mulberry. Increasing lines of evidence have shown its neuroprotective effects against Alzheimer disease and stroke. However, little is known about its neuroprotective effect in Parkinson disease (PD). Owing to its antioxidant activity, blood-brain barrier permeativity, and water solubility, we hypothesized that OXY may exert neuroprotective effects against parkinsonian mimetic 6-hydroxydopamine (6-OHDA) neurotoxicity. Neuroblastoma SH-SY5Y cells have long been used as dopaminergic neurons in PD research. We found that both pretreatment and posttreatment with OXY on SH-SY5Y cells significantly reduced the release of lactate dehydrogenase, the activity of caspase-3, and the generation of intracellular reactive oxygen species triggered by 6-OHDA. Compared to resveratrol, OXY exhibited a wider effective dosage range. We proved that OXY could penetrate the cell membrane by HPLC analysis of cell extracts. These results suggest that OXY may act as an intracellular antioxidant to reduce oxidative stress induced by 6-OHDA. Western blot analysis demonstrated that OXY markedly attenuated 6-OHDA-induced phosphorylation of JNK and c-Jun. Furthermore, we proved that OXY increased the basal levels of SIRT1, which may disclose new pathways accounting for the neuroprotective effects of OXY. Taken together, our results suggest OXY, a dietary phenolic compound, as a potential nutritional candidate for protection against neurodegeneration in PD.

Dietary blueberry supplementation affects growth but not vascularization of neural transplants

Transplantation of neural tissue has been attempted as a treatment method for neurodegenerative disorders. Grafted neurons survive to a lesser extent into middle-aged or aged hosts, and survival rates of <10% of grafted neurons is common. Antioxidant diets, such as blueberry, can exert powerful effects on developing neurons and blood vessels in vitro, but studies are lacking that examine the effects of these diets on transplanted tissues. In this study, we examined the effects of a blueberry diet on survival, growth, and vascularization of fetal hippocampal tissue to the anterior chamber of the eye of young or middle-aged female rats. Previous work from our group showed significant increase in neuronal survival and development with blueberry diet in grafts. However, the effects of antioxidant diet on vascular development in grafts have not been explored previously. The age of the host affected individual vessel morphology in that aged hosts contained grafts with thick, undeveloped walls, and wider lumen. The blood-brain barrier also appeared to be affected by the age of the host. The blueberry diet did not affect vessel morphology or density of vessel-associated protein markers but gave rise to significantly increased growth capacity, cytoarchitecture, and the final size of hippocampal grafts.

Effect of blueberry feeding on plasma lipids in pigs

Two feeding trials were conducted with pigs to determine the effects of blueberry supplementation on plasma lipid levels and other indices of cardiovascular benefit. In the first trial, where basal diets contained a high level of plant-based components (70 % soya, oats and barley), supplementation with 1, 2 and 4 % blueberries resulted in a decrease in total, LDL- and HDL-cholesterol. The greatest reduction was observed in the 2 % blueberry-fed pigs, where total, LDL- and HDL-cholesterol were reduced 11.7, 15.1 and 8.3 %, respectively. In the second trial where basal diets contained only 20 % (w/w) of soya, oats and barley, the lipid-modulating effect of blueberries was attenuated, so that supplementation with 1.5 % blueberries reduced total cholesterol by 8 %, which occurred only in pigs whose diets had been supplemented with cholesterol (0.08 %), NaCl (0.11 %) and fructose (9 %). In the first feeding trial, blueberry supplementation had no effect on blood platelet activity. Blueberry supplementation also had no effect on the susceptibility of leucocyte DNA to oxidation in the first trial and no effect on the susceptibility of LDL to oxidation in the second trial. Results of these two feeding trials are discussed in relation to the effects of basal diet composition on lipid-modulating effects of blueberries.

Oxidative stress of neural, hematopoietic, and stem cells: protection by natural compounds

During natural aging, adult stem cells are known to have a reduced restorative capacity and are more vulnerable to oxidative stress resulting in a reduced ability of the body to heal itself. We report here that the proprietary natural product formulation, NT020, previously found to promote proliferation of human hematopoietic stem cells, reduced oxidative stress-induced apoptosis of murine neurons and microglial cells in vitro. Furthermore, when taken orally for 2 weeks, cultured bone marrow stem cells from these mice exhibited a dose-related reduction of oxidative stress-induced apoptosis. This preclinical study demonstrates that NT020 can act to promote healing via an interaction with stem cell populations and forms the basis of conducting a clinical trial to determine if NT020 exhibits similar health promoting effects in humans when used as a dietary supplement.