The Experts below are selected from a list of 309 Experts worldwide ranked by ideXlab platform
Barbara D Boyan - One of the best experts on this subject based on the ideXlab platform.
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tailoring adipose stem cell Trophic Factor production with differentiation medium components to regenerate chondral defects
Tissue Engineering Part A, 2013Co-Authors: Elyse Watkins, Olivia A Burnsed, Zvi Schwartz, Barbara D BoyanAbstract:Recent endeavors to use stem cells as Trophic Factor production sources have the potential to translate into viable therapies for damaged or diseased musculoskeletal tissues. Adipose stem cells (ASCs) can be differentiated into chondrocytes using the chondrogenic medium (CM), but it is unknown if this approach can optimize ASC growth Factor secretion for cartilage regeneration by increasing the chondrogenic Factor production, while decreasing angiogenic and hyperTrophic Factor production. The objective of this study was to determine the effects the CM and its components have on growth Factor production from ASCs to promote cartilage regeneration. ASCs isolated from male Sprague-Dawley rats and cultured in monolayer or alginate microbeads were treated with either the growth medium (GM) or the CM for 5 days. In subsequent studies, ASC monolayers were treated with either the GM supplemented with different combinations of 50 μg/mL ascorbic acid-2-phosphate (AA2P), 100 nM dexamethasone (Dex), 10 ng/mL transfor...
Alvaro G. Estévez - One of the best experts on this subject based on the ideXlab platform.
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Chronic Inhibitory Effect of Riluzole on Trophic Factor Production
Experimental Neurology, 2015Co-Authors: Cassandra N. Dennys, Jenay Armstrong, Mark Levy, Youn Jung Byun, Kristina Ramdial, Marga Bott, Fabian H. Rossi, Cristina Fernandez-valle, Maria Clara Franco, Alvaro G. EstévezAbstract:Abstract Riluzole is the only FDA approved drug for the treatment of amyoTrophic lateral sclerosis (ALS). However, the drug affords moderate protection to ALS patients, extending life for a few months by a mechanism that remains controversial. In the presence of riluzole, astrocytes increase the production of Factors protective to motor neurons. The stimulation of Trophic Factor production by motor neuron associated cells may contribute to riluzole's protective effect in ALS. Here, we investigated the effects of media conditioned by astrocytes and Schwann cells acutely or chronically incubated with riluzole on Trophic Factor-deprived motor neuron survival. While acute riluzole incubation induced CT-1 secretion by astrocytes and Schwann cells, chronic treatment stimulated a significant decrease in Trophic Factor production compared to untreated cultures. Accordingly, conditioned media from astrocytes and Schwann cells acutely treated with riluzole protected motor neurons from Trophic Factor deprivation-induced cell death. Motor neuron protection was prevented by incubation with CT-1 neutralizing antibodies. In contrast, conditioned media from astrocytes and Schwann cells chronically treated with riluzole was not protective. Acute and chronic treatment of mice with riluzole showed opposite effects on Trophic Factor production in spinal cord, sciatic nerve and brain. There was an increase in the production of CT-1 and GDNF in the spinal cord and CT-1 in the sciatic nerve during the first days of treatment with riluzole, but the levels dropped significantly after chronic treatment with the drug. Similar results were observed in brain for CT-1 and BDNF while there was no change in GDNF levels after riluzole treatment. Our results reveal that riluzole regulates long-lasting processes involving protein synthesis, which may be relevant for riluzole therapeutic effects. Changing the regimen of riluzole administration to favor the acute effect of the drug on Trophic Factor production by discontinuous long-term treatment may improve the outcome of ALS patient therapy.
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arginase 1 regulation of nitric oxide production is key to survival of Trophic Factor deprived motor neurons
The Journal of Neuroscience, 2006Co-Authors: Alvaro G. Estévez, Mary Anne Sahawneh, Philipp S Lange, Mariela Egea, Rajiv R RatanAbstract:When deprived of Trophic Factors, the majority of cultured motor neurons undergo nitric oxide-dependent apoptosis. However, for reasons that have remained unclear, 30–50% of the motor neurons survive for several days without Trophic Factors. Here we hypothesize that the resistance of this motor neuron subpopulation to Trophic Factor deprivation can be attributed to diminished nitric oxide production resulting from the activity of the arginine-degrading enzyme arginase. When incubated with nor-NG-hydroxy-nor-l-arginine (NOHA), the normally resistant Trophic Factor-deprived motor neurons showed a drop in survival rates, whereas Trophic Factor-treated neurons did not. NOHA-induced motor neuron death was inhibited by blocking nitric oxide synthesis and the scavenging of superoxide and peroxynitrite, suggesting that peroxynitrite mediates NOHA toxicity. When we transfected arginase 1 into motor neurons to see whether it alone could abrogate Trophic Factor deprivation-induced death, we found that its forced expression did indeed do so. The protection afforded by arginase 1 expression is reversed when cells are incubated with NOHA or with low concentrations of nitric oxide. These results reveal that arginase acts as a central regulator of Trophic Factor-deprived motor neuron survival by suppressing nitric oxide production and the consequent peroxynitrite toxicity. They also suggest that the resistance of motor neuron subpopulations to Trophic Factor deprivation may result from increased arginase activity.
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liposome delivered superoxide dismutase prevents nitric oxide dependent motor neuron death induced by Trophic Factor withdrawal
Free Radical Biology and Medicine, 2000Co-Authors: Alvaro G. Estévez, Nathan Spear, Luis Barbeito, Jacinda B Sampson, Yingxin Zhuang, G J Richardson, John P Crow, Margaret M Tarpey, Joseph S BeckmanAbstract:Inhibition of nitric oxide synthesis prevents rat embryonic motor neurons from undergoing apoptosis when initially cultured without brain-derived neuroTrophic Factor. Using an improved cell culture medium, we found that the partial withdrawal of Trophic support even weeks after motor neurons had differentiated into a mature phenotype still induced apoptosis through a process dependent upon nitric oxide. However, nitric oxide itself was not directly toxic to motor neurons. To investigate whether intracellular superoxide contributed to nitric oxide–dependent apoptosis, we developed a novel method using pH-sensitive liposomes to deliver Cu, Zn superoxide dismutase intracellularly into motor neurons. Intracellular superoxide dismutase prevented motor neuron apoptosis from Trophic Factor withdrawal, whereas empty liposomes, inactivated superoxide dismutase in liposomes or extracellular superoxide dismutase did not. Neither hydrogen peroxide nor nitrite added separately or in combination affected motor neuron survival. Our results suggest that a partial reduction in Trophic support induced motor neuron apoptosis by a process requiring the endogenous production of both nitric oxide and superoxide, irrespective of the extent of motor neuron maturation in culture.
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nitric oxide and superoxide contribute to motor neuron apoptosis induced by Trophic Factor deprivation
The Journal of Neuroscience, 1998Co-Authors: Alvaro G. Estévez, Nathan Spear, Machelle S Manuel, Rafael Radi, Christopher E Henderson, Luis Barbeito, Joseph S BeckmanAbstract:Primary cultures of rat embryonic motor neurons deprived of brain-derived neuroTrophic Factor (BDNF) induce neuronal nitric oxide synthase (NOS) within 18 hr. Subsequently, >60% of the neurons undergo apoptosis between 18 and 24 hr after plating. Nitro-l-arginine and nitro-l-arginine methyl ester (l-NAME) prevented motor neuron death induced by Trophic Factor deprivation. Exogenous generation of nitric oxide at concentrations lower than 100 nm overcame the protection byl-NAME. Manganese tetrakis (4-benzoyl acid) porphyrin, a cell-permeant superoxide scavenger, also prevented nitric oxide-dependent motor neuron death. Motor neurons cultured without Trophic support rapidly became immunoreactive for nitrotyrosine when compared with motor neurons incubated with BDNF, l-NAME, or manganese TBAP. Our results suggest that peroxynitrite, a strong oxidant formed by the reaction of NO and superoxide, plays an important role in the induction of apoptosis in motor neurons deprived of Trophic Factors and that BDNF supports motor neuron survival in part by preventing neuronal NOS expression.
Michael G Fehlings - One of the best experts on this subject based on the ideXlab platform.
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an in vivo characterization of Trophic Factor production following neural precursor cell or bone marrow stromal cell transplantation for spinal cord injury
Stem Cells and Development, 2012Co-Authors: Gregory W J Hawryluk, Andrea J Mothe, Jian Wang, Charles H Tator, Shelly Wang, Michael G FehlingsAbstract:Cellular transplantation strategies for repairing the injured spinal cord have shown consistent benefit in preclinical models, and human clinical trials have begun. Interactions between transplanted cells and host tissue remain poorly understood. Trophic Factor secretion is postulated a primary or supplementary mechanism of action for many transplanted cells, however, there is little direct evidence to support trophin production by transplanted cells in situ. In the present study, Trophic Factor expression was characterized in uninjured, injured-untreated, injured-treated with transplanted cells, and corresponding control tissue from the adult rat spinal cord. Candidate Trophic Factors were identified in a literature search, and primers were designed for these genes. We examined in vivo trophin expression in 3 paradigms involving transplantation of either brain or spinal cord-derived neural precursor cells (NPCs) or bone marrow stromal cells (BMSCs). Injury without further treatment led to a significant e...
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in vitro characterization of Trophic Factor expression in neural precursor cells
Stem Cells and Development, 2012Co-Authors: Gregory W J Hawryluk, Andrea J Mothe, Mahmood Chamankhah, Jian Wang, Charles H Tator, Michael G FehlingsAbstract:In cellular transplantation strategies for repairing the injured central nervous system, interactions between transplanted neural precursor cells (NPCs) and host tissue remain incompletely understood. Although trophins may contribute to the benefits observed, little research has explored this possibility. Candidate Trophic Factors were identified, and primers were designed for these genes. Template RNA was isolated from 3 NPC sources, and also from bone marrow stromal cells (BMSCs) and embryonic fibroblasts as comparative controls. Quantitative polymerase chain reaction was performed to determine the effect of cell source, passaging, cellular differentiation, and environmental changes on trophin Factor expression in NPCs. Results were analyzed with multivariate statistical analyses. NPCs, BMSCs, and fibroblasts each expressed Trophic Factors in unique patterns. Trophic Factor expression was similar among NPCs whether harvested from rat or mouse, brain or spinal cord, or their time in culture. The expressi...
Larry I Benowitz - One of the best experts on this subject based on the ideXlab platform.
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an injectable biodegradable hydrogel for Trophic Factor delivery enhances axonal rewiring and improves performance after spinal cord injury
Experimental Neurology, 2006Co-Authors: J Piantino, Jason A Burdick, David E Goldberg, Robert Langer, Larry I BenowitzAbstract:The failure of long descending pathways to regenerate after spinal cord injury (SCI) is generally attributed to inhibitory proteins associated with the glial scar and myelin, or to the loss of neurons' intrinsic capacity to grow, or both. Here, we describe the use of hydrogels as a novel way to deliver molecules that promote axon growth in the injured CNS of adult rats. This method utilizes an injectable liquid polymer solution that crosslinks into a biodegradable, water-swollen hydrogel when photoactivated under visible light. Neurotrophin-3 (NT-3), a Trophic Factor known to act on corticospinal tract (CST) projection neurons, was used as a prototypic pro-regenerative molecule. Hydrogel release properties were established in vitro to ensure long-term, sustained NT-3 release over a 2-week period; this avoided the need for multiple injections or minipump implantation. Hydrogel/NT-3-treated animals showed improved recovery in the open-field BBB test and in a horizontal ladder walk test compared to controls implanted with hydrogel alone. At the anatomical level, hydrogel/NT-3-treated animals showed far greater axon growth than controls in two major descending pathways for motor control, the CST and the raphespinal tract. In the case of the CST, much of the NT-3-induced growth represented collateral branching from undamaged ventral CST fibers. These studies demonstrate the effectiveness of hydrogel technology as a clinically feasible delivery system to promote regeneration and enhance functional outcome after spinal cord injury.
Mark P Mattson - One of the best experts on this subject based on the ideXlab platform.
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prostate apoptosis response 4 mediates Trophic Factor withdrawal induced apoptosis of hippocampal neurons actions prior to mitochondrial dysfunction and caspase activation
Journal of Neurochemistry, 2002Co-Authors: Sic L Chan, Steven P Tammariello, Steve Estus, Mark P MattsonAbstract:Abstract : Prostate apoptosis response-4 (Par-4) is the product of a gene up-regulated in prostate cancer cells undergoing apoptosis. We now report that Par-4 mRNA and protein levels rapidly and progressively increase 4-24 h following Trophic Factor withdrawal (TFW) in cultured embryonic rat hippocampal neurons. The increased Par-4 levels follow an increase of reactive oxygen species, and precede mitochondrial membrane depolarization, caspase activation, and nuclear chromatin condensation/fragmentation. Pretreatment of cultures with 17β-estradiol, vitamin E, and uric acid largely prevented Par-4 induction and cell death following TFW, demonstrating necessary roles for oxidative stress and membrane lipid peroxidation in TFW-induced neuronal apoptosis. Par-4 antisense oligonucleotide treatment blocked Par-4 protein increases and attenuated mitochondrial dysfunction, caspase activation, and cell death following TFW. Collectively, our data identify Par-4 as an early and pivotal player in neuronal apoptosis resulting from TFW and suggest that estrogen and antioxidants may prevent apoptosis, in part, by suppressing Par-4 production.
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alzheimer s presenilin mutation sensitizes neural cells to apoptosis induced by Trophic Factor withdrawal and amyloid β peptide involvement of calcium and oxyradicals
The Journal of Neuroscience, 1997Co-Authors: Bryce L Sopher, Katsutoshi Furukawa, Dao G Pham, Nic Robinson, George M Martin, Mark P MattsonAbstract:Most autosomal dominant inherited forms of early onset Alzheimer’s disease (AD) are caused by mutations in the presenilin-1 (PS-1) gene on chromosome 14. PS-1 is an integral membrane protein with six to nine membrane-spanning domains and is expressed in neurons throughout the brain wherein it is localized mainly in endoplasmic reticulum (ER). The mechanism or mechanisms whereby PS-1 mutations promote neuron degeneration in AD are unknown. Recent findings suggest links among deposition of amyloid β-peptide (Aβ), oxidative stress, disruption of ion homeostasis, and an apoptotic form of neuron death in AD. We now report that expression of the human PS-1 L286V mutation in PC12 cells increases their susceptibility to apoptosis induced by Trophic Factor withdrawal and Aβ. Increases in oxidative stress and intracellular calcium levels induced by the apoptotic stimuli were exacerbated greatly in cells expressing the PS-1 mutation, as compared with control cell lines and lines overexpressing wild-type PS-1. The antiapoptotic gene product Bcl-2 prevented apoptosis after NGF withdrawal from differentiated PC12 cells expressing mutant PS-1. Elevations of [Ca2+]i in response to thapsigargin, an inhibitor of the ER Ca2+-ATPase, were increased in cells expressing mutant PS-1, and this adverse effect was abolished in cells expressing Bcl-2. Antioxidants and blockers of calcium influx and release from ER protected cells against the adverse consequences of the PS-1 mutation. By perturbing cellular calcium regulation and promoting oxidative stress, PS-1 mutations may sensitize neurons to apoptotic death in AD.