Bone morphogenetic proteins are involved in fetal kidney tissue transplantation-induced neuroprotection in stroke rats

Therapeutic Effect of Rapamycin on TDP-43-Related Pathogenesis in Ischemic Stroke

Stroke is a major cause of death and disability across the world, and its detrimental impact should not be underestimated. Therapies are available and effective for ischemic stroke (e.g., thrombolytic recanalization and mechanical thrombectomy); however, there are limitations to therapeutic interventions. Recanalization therapy has developed dramatically, while the use of adjunct neuroprotective agents as complementary therapies remains deficient. Pathological TAR DNA-binding protein (TDP-43) has been identified as a major component of insoluble aggregates in numerous neurodegenerative pathologies, including ALS, FTLD and Alzheimer's disease. Here, we show that increased pathological TDP-43 fractions accompanied by impaired mitochondrial function and increased gliosis were observed in an ischemic stroke rat model, suggesting a pathological role of TDP-43 in ischemic stroke. In ischemic rats administered rapamycin, the insoluble TDP-43 fraction was significantly decreased in the ischemic cortex region, accompanied by a recovery of mitochondrial function, the attenuation of cellular apoptosis, a reduction in infarct areas and improvements in motor defects. Accordingly, our results suggest that rapamycin provides neuroprotective benefits not only by ameliorating pathological TDP-43 levels, but also by reversing mitochondrial function and attenuating cell apoptosis in ischemic stroke.

BMP-6 Attenuates Oxygen and Glucose Deprivation-Induced Apoptosis in Human Neural Stem Cells through Inhibiting p38 MAPK Signaling Pathway

Background and Objectives

Neural stem cells (NSCs) remain in the mammalian brain throughout life and provide a novel therapeutic strategy for central nervous system (CNS) injury. Bone morphogenetic protein-6 (BMP-6) had shown a protective effect in different types of cells. However, the role of BMP-6 in NSCs is largely unclear. The present study was aimed to investigate whether BMP-6 could protect human NSCs (hNSCs) against the oxygen and glucose deprivation (OGD)-induced cell death.

Methods and Results

Upon challenge with OGD treatment, cell viability was significantly decreased in a time-dependent manner, as indicated by the CCK-8 assay. BMP-6 could attenuate the OGD-induced cell injury in a dose-dependent manner and decrease the number of TUNEL-positive cells. Moreover, BMP-6 markedly weakened the OGD-induced alterations in the expression of procaspase-8/9/3 and reversed the expression of cleaved-caspase-3. Interestingly, noggin protein (the BMP-6 inhibitor) attenuated the neuroprotective effect of BMP-6 in cultured hNSCs. Furthermore, the p38 MAPK signaling pathway was activated by OGD treatment and BMP-6 markedly inhibited the phosphorylation of p38 in a concentration-dependent manner. Pretreatment with noggin abolished the effect of BMP-6 on p38 activation. SB239063, a selective p38 inhibitor, exerted similar effects with BMP-6 in protecting hNSCs against the OGD-induced apoptosis. These results indicated that blocking the phosphorylation of p38 might contribute to the neuroprotective effect of BMP-6 against the OGD-induced injury in hNSCs.

Conclusions

These findings suggested that BMP-6 might be a therapeutic target in the OGD-induced cell death, which provides a novel therapeutic strategy for enhancing host and graft NSCs survival in hypoxic-ischemic brain injury.

Neuroprotective Effects of Emodin against Ischemia/Reperfusion Injury through Activating ERK-1/2 Signaling Pathway

Background: Stroke is one of the leading causes of death and disability worldwide and places a heavy burden on the economy in our society. Current treatments, such as the use of thrombolytic agents, are often limited by a narrow therapeutic time window. However, the regeneration of the brain after damage is still active days, even weeks, after stroke occurs, which might provide a second window for treatment. Emodin, a traditional Chinese medicinal herb widely used to treat acute hepatitis, has been reported to possess antioxidative capabilities and protective effects against myocardial ischemia/reperfusion injury. However, the underlying mechanisms and neuroprotective functions of Emodin in a rat middle cerebral artery occlusion (MCAO) model of ischemic stroke remain unknown. This study investigates neuroprotective effects of Emodin in ischemia both in vitro and in vivo. Methods: PC12 cells were exposed to oxygen-glucose deprivation to simulate hypoxic injury, and the involved signaling pathways and results of Emodin treatment were evaluated. The therapeutic effects of Emodin in ischemia animals were further investigated. Results: Emodin reduced infarct volume and cell death following focal cerebral ischemia injury. Emodin treatment restored PC12 cell viability and reduced reactive oxygen species (ROS) production and glutamate release under conditions of ischemia/hypoxia. Emodin increased Bcl-2 and glutamate transporter-1 (GLT-l) expression but suppressed activated-caspase 3 levels through activating the extracellular signal-regulated kinase (ERK)-1/2 signaling pathway. Conclusion: Emodin induced Bcl-2 and GLT-1 expression to inhibit neuronal apoptosis and ROS generation while reducing glutamate toxicity via the ERK-1/2 signaling pathway. Furthermore, Emodin alleviated nerve cell injury following ischemia/reperfusion in a rat MCAO model. Emodin has neuroprotective effects against ischemia/reperfusion injury both in vitro and in vivo, which may be through activating the ERK-1/2 signaling pathway.

Pomalidomide Ameliorates H₂O₂-Induced Oxidative Stress Injury and Cell Death in Rat Primary Cortical Neuronal Cultures by Inducing Anti-Oxidative and Anti-Apoptosis Effects

Due to its high oxygen demand and abundance of peroxidation-susceptible lipid cells, the brain is particularly vulnerable to oxidative stress. Induced by a redox state imbalance involving either excessive generation of reactive oxygen species (ROS) or dysfunction of the antioxidant system, oxidative stress plays a central role in a common pathophysiology that underpins neuronal cell death in acute neurological disorders epitomized by stroke and chronic ones such as Alzheimer’s disease. After cerebral ischemia, for example, inflammation bears a key responsibility in the development of permanent neurological damage. ROS are involved in the mechanism of post-ischemic inflammation. The activation of several inflammatory enzymes produces ROS, which subsequently suppress mitochondrial activity, leading to further tissue damage. Pomalidomide (POM) is a clinically available immunomodulatory and anti-inflammatory agent. Using H₂O₂-treated rat primary cortical neuronal cultures, we found POM displayed neuroprotective effects against oxidative stress and cell death that associated with changes in the nuclear factor erythroid derived 2/superoxide dismutase 2/catalase signaling pathway. POM also suppressed nuclear factor kappa-light-chain-enhancer (NF-κB) levels and significantly mitigated cortical neuronal apoptosis by regulating Bax, Cytochrome c and Poly (ADP-ribose) polymerase. In summary, POM exerted neuroprotective effects via its anti-oxidative and anti-inflammatory actions against H₂O₂-induced injury. POM consequently represents a potential therapeutic agent against brain damage and related disorders and warrants further evaluation.

Neuroprotective Action of Human Wharton's Jelly-Derived Mesenchymal Stromal Cell Transplants in a Rodent Model of Stroke

Wharton’s jelly-derived mesenchymal stromal cells (WJ-MSCs) have distinct immunomodulatory and protective effects against kidney, liver, or heart injury. Limited studies have shown that WJ-MSCs attenuates oxygen–glucose deprivation-mediated inflammation in hippocampal slices. The neuroprotective effect of intracerebral WJ-MSC transplantation against stroke has not been well characterized. The purpose of this study was to examine the neuroprotective effect of human WJ-MSC (hWJ-MSC) transplants in an animal model of stroke. Adult male Sprague–Dawley rats were anesthetized and placed in a stereotaxic frame. hWJ-MSCs, pre-labeled with chloromethyl benzamide 1,1’-dioctadecyl-3,3,3’3’- tetramethylindocarbocyanine perchlorate (CM-Dil), were transplanted to the right cerebral cortex at 10 min before a transient (60 min) right middle cerebral artery occlusion (MCAo). Transplantation of hWJ-MSCs significantly reduced neurological deficits at 3 and 5 days after MCAo. hWJ-MSC transplants also significantly reduced brain infarction and microglia activation in the penumbra. Grafted cells carrying CM-Dil fluorescence were identified at the grafted site in the ischemic core; these cells were mostly incorporated into ionized calcium-binding adaptor molecule (+) cells, suggesting these xenograft cells were immuno-rejected by the host. In another set of animals, hWJ-MSCs were transplanted in cyclosporine (CsA)-treated rats. hWJ-MSC transplants significantly reduced brain infarction, improved neurological function, and reduced neuroinflammation. Less phagocytosis of CM-dil-labeled grafted cells was found in the host brain after CsA treatment. Transplantation of hWJ-MSC significantly increased glia cell line-derived neurotrophic factor expression in the host brain. Taken together, our data support that intracerebral transplantation of hWJ-MSCs reduced neurodegeneration and inflammation in the stroke brain. The protective effect did not depend on the survival of grafted cells but may be indirectly mediated through the production of protective trophic factors from the transplants.

(-)-Phenserine inhibits neuronal apoptosis following ischemia/reperfusion injury

Stroke commonly leads to adult disability and death worldwide. Its major symptoms are spastic hemiplegia and discordant motion, consequent to neuronal cell death induced by brain vessel occlusion. Acetylcholinesterase (AChE) is upregulated and allied with inflammation and apoptosis after stroke. Recent studies suggest that AChE inhibition ameliorates ischemia-reperfusion injury and has neuroprotective properties. (-)-Phenserine, a reversible AChE inhibitor, has a broad range of actions independent of its AChE properties, including neuroprotective ones. However, its protective effects and detailed mechanism of action in the rat middle cerebral artery occlusion model (MCAO) remain to be elucidated. This study investigated the therapeutic effects of (-)-phenserine for stroke in the rat focal cerebral ischemia model and oxygen-glucose deprivation/reperfusion (OGD/RP) damage model in SH-SY5Y neuronal cultures. (-)-Phenserine mitigated OGD/PR-induced SH-SY5Y cell death, providing an inverted U-shaped dose-response relationship between concentration and survival. In MCAO challenged rats, (-)-phenserine reduced infarction volume, cell death and improved body asymmetry, a behavioral measure of stoke impact. In both cellular and animal studies, (-)-phenserine elevated brain-derived neurotrophic factor (BDNF) and B-cell lymphoma 2 (Bcl-2) levels, and decreased activated-caspase 3, amyloid precursor protein (APP) and glial fibrillary acidic protein (GFAP) expression, potentially mediated through the ERK-1/2 signaling pathway. These actions mitigated neuronal apoptosis in the stroke penumbra, and decreased matrix metallopeptidase-9 (MMP-9) expression. In synopsis, (-)-phenserine significantly reduced neuronal damage induced by ischemia/reperfusion injury in a rat model of MCAO and cellular model of OGD/RP, demonstrating that its anti-apoptotic/neuroprotective/neurotrophic cholinergic and non-cholinergic properties warrant further evaluation in conditions of brain injury.

9-cis retinoic acid induces neurorepair in stroke brain

The purpose of this study was to examine the neurorestorative effect of delayed 9 cis retinoic acid (9cRA) treatment for stroke. Adult male rats received a 90-min right distal middle cerebral artery occlusion (dMCAo). Animals were separated into two groups with similar infarction sizes, based on magnetic resonance imaging on day 2 after dMCAo. 9cRA or vehicle was given via an intranasal route daily starting from day 3. Stroke rats receiving 9cRA post-treatment showed an increase in brain 9cRA levels and greater recovery in motor function. 9cRA enhanced the proliferation of bromodeoxyuridine (+) cells in the subventricular zone (SVZ) and lesioned cortex in the stroke brain. Using subventricular neurosphere and matrigel cultures, we demonstrated that proliferation and migration of SVZ neuroprogenitor cells were enhanced by 9cRA. Our data support a delayed and non-invasive drug therapy for stroke. Intranasal 9cRA can facilitate the functional recovery and endogenous repair in the ischemic brain.

Transplantation of Fetal Kidney Cells: Neuroprotection and Neuroregeneration

Various trophic factors in the transforming growth factor-β (TGF-β) superfamily have been reported to have neuroprotective and neuroregenerative effects. Intracerebral administration of glial cell line-derived neurotrophic factor (GDNF) or bone morphogenetic proteins (BMPs), both members of the TGF-β family, reduce ischemia- or 6-hydroxydopamine (6-OHDA)-induced injury in adult rat brain. Because BMPs and GDNF are highly expressed in fetal kidney cells, transplantation of fetal kidney tissue could serve as a cellular reservoir for such molecules and protect against neuronal injury induced by ischemia, neurotoxins, or reactive oxygen species. In this review, we discuss preclinical evidence for the efficacy of fetal kidney cell transplantation in neuroprotection and regeneration models.

A Novel CXCR4 Antagonist CX549 Induces Neuroprotection in Stroke Brain

C-X-C chemokine receptor type 4 (CXCR4) is a receptor for a pleiotropic chemokine CXCL12. Previous studies have shown that the acute administration of the CXCR4 antagonist AMD3100 reduced neuroinflammation in stroke brain and mobilized bone marrow hematopoietic stem cells (HSCs). The purpose of this study was to characterize the neuroprotective and neurotrophic effect of a novel CXCR4 antagonist CX549. We demonstrated that CX549 had a higher affinity for CXCR4 and was more potent than AMD3100 to inhibit CXCL12-mediated chemotaxis in culture. CX549 effectively reduced the activation of microglia and improved neuronal survival after injury in neuron/microglia cocultures. Early poststroke treatment with CX549 significantly improved behavioral function, reduced brain infarction, and suppressed the expression of inflammatory markers. Compared to AMD3100, CX549 has a higher affinity for CXCR4, is more efficient to mobilize HSCs for transplantation, and induces behavioral improvement. Our data support that CX549 is a potent anti-inflammatory agent, is neuroprotective against ischemic brain injury, and may have clinical implications for the treatment of stroke.

Time-Dependent Protection of CB2 Receptor Agonist in Stroke

Recent studies have indicated that type 2 cannabinoid receptor (CB2R) agonists reduce neurodegeneration after brain injury through anti-inflammatory activity. The purpose of this study was to examine the time-dependent interaction of CB2R and inflammation in stroke brain. Adult male rats were subjected to right middle cerebral artery occlusion (MCAo). CB2R mRNA expression was significantly elevated >20 fold on day 2, peaked >40-fold on day 5, and normalized on day 10 post-stroke. Inflammatory markers IBA1 and TLR4 were significantly upregulated 15 fold until day 5 after MCAo. Because of the delayed upregulation of CB2R and IBA1, we next treated animals daily with CB2R agonist AM1241 or anti-inflammatory PPAR-γ agonist pioglitazone from 2 to 5 days after MCAo. Delayed treatment with pioglitazone significantly reduced abnormal neurological scores and body asymmetry as well as brain infarction in stroke animals. No behavioral improvement or reduction in brain infarction was found in animals receiving AM1241. Pioglitazone, but not AM1241, significantly reduced IBA1 expression in the stroke cortex, suggesting that delayed treatment with AM1241 failed to alter ischemia-mediated IBA-1 upregulation. In contrast, pretreatment with AM1241 significantly reduced brain infarction and neurological deficits. In conclusion, our data support a time-dependent neuroprotection of CB2 agonist in an animal model of stroke. Delayed post- treatment with PPAR-γ agonist induced behavioral recovery and microglial suppression; early treatment with CB2R agonist suppressed neurodegeneration in stroke animals.

Post-hypoxic and ischemic neuroprotection of BMP-7 in the cerebral cortex and caudate-putamen tissue of rat

Previous reports have indicated that exogenous bone morphogenetic protein-7 (BMP-7) has a neuroprotective effect after cerebral ischemia injury and promotes motor function recovery, but the appropriate BMP-7 concentration and time course are unclear. Here, we assessed endogenous BMP-7 expression in hypoxia and ischemia-damaged brain tissues and investigated the effects of different BMP-7 concentrations in pre- and post-hypoxic primary rat neurons. The results showed that BMP-7 expression was significantly higher in the ischemic hemisphere. The expressions of BMP-7 and caspase-3 were localized in the cytoplasm of the primary cerebral cortical and caudate-putamen neurons 24h after hypoxia/reoxygenation. After BMP-7 treatment, the number of caspase-3 positive neurons began to decrease with increasing BMP-7 concentrations up to 80ng/ml, but not beyond. Although the numbers of caspase-3-positive neurons between pre- and post-hypoxia/reoxygenation were not significantly different, more dendrites were observed in the groups treated prior to hypoxia/reoxygenation. These results suggest that increased BMP-7 expression can be induced in the cerebral cortex and caudate-putamen both in vivo and in vitro in hypoxic-ischemic states. The neuroprotective mechanism of BMP-7 may include apoptosis suppression, and its effect was enhanced from 40 to 80ng/ml. Pre-hypoxic BMP-7 treatment may be useful to stimulate dendrite sprouting in non-injured neurons.

Transplantation of Human Placenta-Derived Multipotent Stem Cells Reduces Ischemic Brain Injury in Adult Rats

After the onset of stroke, a series of progressive and degenerative reactions, including inflammation, is activated, which leads to cell death. We recently reported that human placenta-derived multipotent stem cells (hPDMCs) process potent anti-inflammatory effects. In this study, we examined the protective effect of hPDMC transplants in a rodent model of stroke. Adult male Sprague–Dawley rats were anesthetized. hPDMCs labeled with a vital dye of fluorescing microparticles, DiI, or vehicle were transplanted into three cortical areas adjacent to the right middle cerebral artery (MCA). Five minutes after grafting, the right MCA was transiently occluded for 60 min. Stroke animals receiving hPDMCs showed a significant behavioral improvement and reduction in lesion volume examined by T2-weighted images 4 days poststroke. Brain tissues were collected 1 day later. Human-specific marker HuNu immunoreactivity and DiI fluorescence were found at the hPDMC graft sites, suggesting the survival of hPDMCs in host brain. Grafting of hPDMCs suppressed IBA1 immunoreactivity and deramification of IBA1+ cells in the perilesioned area, suggesting activation of microglia was attenuated by the transplants. Taken together, our data indicate that hPDMC transplantation reduced cortical lesions and behavioral deficits in adult stroke rats, and these cells could serve as a unique anti-inflammatory reservoir for the treatment of ischemic brain injury.

Neuroprotection by rAAV-mediated gene transfer of bone morphogenic protein 7

Background

Bone morphogenic proteins (BMPs) promote the survival of neurons, suggesting a therapeutic application of BMPs in the treatment of acute and chronic neurodegenerative disorders. However, the application of recombinant BMPs in vivo is limited by their short half-life. To provide a continuous supply for functionally active BMPs, we expressed BMP7, BMP2 and the BMP inhibitor Noggin under the control of rAAV vectors in vivo. For visual control of rAAV-mediated BMP (v-BMP) expression we fused the secreted morphogenic polypeptides and the fluorescent reporter protein Venus via the ‘ribosomal skip’ promoting 2A peptide-bridge.

Results

In primary cortical neurons, the rAAV-expressed morphogenic polypeptides were efficiently released from the 2A-Venus fusion precursors, were secreted, correctly processed and functionally active as shown by their effects on Smad phosphorylation in HeLa cells and in primary neurons, by the protection of v-BMP7-transduced primary cortical neurons against oxidative stress, and by the activation of BMP responsive GFP in v-BMP2 transduced reporter mice. In the stroke model of middle cerebral artery occlusion rAAV-transduced v-BMP7 reduced the infarct size in mice.

Conclusion

Polycistronic rAAV vectors encoding secreted polypeptides and 2A-linked reporter proteins are potential novel therapeutic tools for the treatment of neurological and neurodegenerative diseases. Using this technique we documented that rAAV delivery of BMP7 reduced ischemic cell death in mice.

Protective effects of recombinant human bone morphogenetic protein-7 on focal cerebral ischemia-reperfusion injury

This study was to investigate the protective effect of recombinant human bone morphogenetic protein-7 (rhBMP-7) on focal cerebral ischemia-reperfusion (IR) injuries and their underlying mechanisms. An intraluminal suture method was used to generate a middle cerebral artery occlusion model in rats, which was followed by reperfusion. A sham operation (SO) group underwent the procedure without occlusion, whereas an IR group and rhBMP-7 treated group (RT) underwent occlusion in the absence and presence of rhBMP-7 (250 μg/kg) administered via a femoral vein injection 30 minutes prior to reperfusion. Twenty-four hours after reperfusion, neurological function, brain water content and morphological alterations were examined. Apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling assays, and immunohistochemical staining and Western blot assays were used to detect nuclear nuclear factor-kappa B (NF-κB) p65 expression. Compared with the SO group, IR rats showed a decrease in neurological function, an increase in brain water content, and pathological and morphological damage (p < 0.05). Higher levels of apoptosis were also detected in the infarct region area. In contrast, RT rats had reduced injury after IR. In addition, while immunohistochemical staining and western blot assays consistently detected increased expression of nuclear NF-κB after IR, these levels were reduced in the RT group. Administration of rhBMP-7 prior to reperfusion effectively inhibited the extent of IR injury by attenuating cerebral edema and ameliorating ultrastructural damage. The underlying mechanisms responsible for these observations potentially involve the inhibition of apoptosis induced by IR by rhBMP-7 via an NF-κB-related signaling cascade.

CART peptide induces neuroregeneration in stroke rats

Utilizing a classic stroke model in rodents, middle cerebral artery occlusion (MCAo), we describe a novel neuroregenerative approach using the repeated intranasal administration of cocaine- and amphetamine-regulated transcript (CART) peptide starting from day 3 poststroke for enhancing the functional recovery of injured brain. Adult rats were separated into two groups with similar infarction sizes, measured by magnetic resonance imaging on day 2 after MCAo, and were treated with CART or vehicle. The CART treatment increased CART level in the brain, improved behavioral recovery, and reduced neurological scores. In the subventricular zone (SVZ), CART enhanced immunolabeling of bromodeoxyuridine, a neural progenitor cell marker Musashi-1, and the proliferating cell nuclear antigen, as well as upregulated brain-derived neurotrophic factor (BDNF) mRNA. AAV-GFP was locally applied to the SVZ to examine migration of SVZ cells. The CART enhanced migration of GFP(+) cells from SVZ toward the ischemic cortex. In SVZ culture, CART increased the size of neurospheres. The CART-mediated cell migration from SVZ explants was reduced by anti-BDNF blocking antibody. Using (1)H-MRS (proton magnetic resonance spectroscopy), increases in N-acetylaspartate levels were found in the lesioned cortex after CART treatment in stroke brain. Cocaine- and amphetamine-regulated transcript increased the expression of GAP43 and fluoro-ruby fluorescence in the lesioned cortex. In conclusion, our data suggest that intranasal CART treatment facilitates neuroregeneration in stroke brain.

Early post-treatment with 9-cis retinoic acid reduces neurodegeneration of dopaminergic neurons in a rat model of Parkinson's disease

Background

Retinoic acid (RA) is a biologically active derivative of vitamin A. Previous studies have demonstrated that RA has protective effects against damage caused by H₂O₂ or oxygen-glucose deprivation in mesangial and PC12 cells. Pretreatment with 9-cis-retinoic acid (9cRA) reduced infarction and TUNEL labeling in cerebral cortex as well as attenuated neurological deficits after distal middle cerebral artery occlusion in rats. The purpose of this study was to examine a protective role of 9cRA in dopaminergic (DA) neurons in a typical rodent model of Parkinson’s disease (PD).

Results

The protective role of 9cRA was first examined in rat primary ventromesencephalic culture. Treatment with 9cRA significantly reduced 6-hydroxydopamine (6-OHDA)-mediated cell death and TUNEL labeling in cultured dopaminergic neurons. The protective effect was also examined in adult male rats. Animals received unilateral 6-OHDA lesioning at the left medial forebrain bundle on day 0. Methamphetamine -induced rotational behavior was examined on days 6, 20 and 30 after lesioning. Animals were separated into 2 groups to balance rotational behavior and lesion extent on day 6 and were treated with either 9cRA or vehicle (i.c.v. on day 7 + intra-nasal from day 8 to day 14). Post-treatment with 9cRA significantly reduced methamphetamine –mediated ipislateral rotation at 20 and 30 days after lesioning. In vivo voltammetry was used to examine DA overflow in striatum. Treatment with 9cRA significantly increased KCl -evoked DA release in the lesioned striatum. 9cRA also increased tyrosine hydroxylase (+) cell number in the lesioned nigra as determined by unbiased stereology.

Conclusion

Our data suggests that early post-treatment with 9cRA has a protective effect against neurodegeneration in nigrostriatal DA neurons in an animal model of PD.

The bone morphogenetic protein antagonist noggin protects white matter after perinatal hypoxia-ischemia

Hypoxia-ischemia (HI) in the neonate leads to white matter injury and subsequently cerebral palsy. We find that expression of bone morphogenetic protein 4 (BMP4) increases in the neonatal mouse brain after unilateral common carotid artery ligation followed by hypoxia. Since signaling by the BMP family of factors is a potent inhibitor of oligodendroglial differentiation, we tested the hypothesis that antagonism of BMP signaling would prevent loss of oligodendroglia (OL) and white matter in a mouse model of perinatal HI. Perinatal HI was induced in transgenic mice in which the BMP antagonist noggin is overexpressed during oligodendrogenesis (pNSE-Noggin). Following perinatal HI, pNSE-Noggin mice had more oligodendroglial progenitor cells (OPCs) and more mature OL compared to wild type (WT) animals. The increase in OPC numbers did not result from proliferation but rather from increased differentiation from precursor cells. Immunofluorescence studies showed preservation of white matter in lesioned pNSE-Noggin mice compared to lesioned WT animals. Further, following perinatal HI, the pNSE-Noggin mice were protected from gait deficits. Together these findings indicate that the BMP-inhibitor noggin protects from HI-induced loss of oligodendroglial lineage cells and white matter as well as loss of motor function.

Noggin protects against ischemic brain injury in rodents

BACKGROUND AND PURPOSE

Bone morphogenetic proteins and their receptors are expressed in adult brains, and their expression levels increase after cerebral ischemia. The brain also expresses an inhibitor of bone morphogenetic protein signaling, noggin, but the role of noggin in ischemic disease outcome has not been studied.

METHODS

We used transgenic mice overexpressing noggin to assess whether inhibition of bone morphogenetic protein signaling affects ischemic injury responses after permanent middle cerebral artery occlusion.

RESULTS

Transgenic mice overexpressing noggin mice had significantly smaller infarct volumes and lower motor deficits compared to wild-type mice. CD11b(+) and IBA1(+) microglia along with oligodendroglial progenitors were significantly increased in transgenic mice overexpressing noggin mice at 14 days after permanent middle cerebral artery occlusion.

CONCLUSIONS

These results provide genetic evidence that overexpression of noggin reduces ischemic brain injury after permanent middle cerebral artery occlusion via enhanced activation of microglia and oligodendrogenesis.

9-Cis-retinoic acid reduces ischemic brain injury in rodents via bone morphogenetic protein

Retinoic acid (RA), a biologically active derivative of vitamin A, has protective effects against damage caused by H(2)O(2) or oxygen-glucose deprivation in mesangial and PC12 cells. In cultured human osteosarcoma cells, RA enhances the expression of bone morphogenetic protein-7 (BMP7), a trophic factor that reduces ischemia- or neurotoxin-mediated neurodegeneration in vivo. The purpose of this study is to examine whether RA reduces ischemic brain injury through a BMP7 mechanism. We found that intracerebroventricular administration of 9-cis-retinoic acid (9cRA) enhanced BMP7 mRNA expression, detected by RT-PCR, in rat cerebral cortex at 24 hr after injection. Rats were also subjected to transient focal ischemia induced by ligation of the middle cerebral artery (MCA) at 1 day after 9cRA injection. Pretreatment with 9cRA increased locomotor activity and attenuated neurological deficits 2 days after MCA ligation. 9cRA also reduced cerebral infarction and TUNEL labeling. These protective responses were antagonized by the BMP antagonist noggin given 1 day after 9cRA injection. Taken together, our data suggest that 9cRA has protective effects against ischemia-induced injury, and these effects involve BMPs.

Astaxanthin reduces ischemic brain injury in adult rats

Astaxanthin (ATX) is a dietary carotenoid of crustaceans and fish that contributes to their coloration. Dietary ATX is important for development and survival of salmonids and crustaceans and has been shown to reduce cardiac ischemic injury in rodents. The purpose of this study was to examine whether ATX can protect against ischemic injury in the mammalian brain. Adult rats were injected intracerebroventricularly with ATX or vehicle prior to a 60-min middle cerebral artery occlusion (MCAo). ATX was present in the infarction area at 70-75 min after onset of MCAo. Treatment with ATX, compared to vehicle, increased locomotor activity in stroke rats and reduced cerebral infarction at 2 d after MCAo. To evaluate the protective mechanisms of ATX against stroke, brain tissues were assayed for free radical damage, apoptosis, and excitoxicity. ATX antagonized ischemia-mediated loss of aconitase activity and reduced glutamate release, lipid peroxidation, translocation of cytochrome c, and TUNEL labeling in the ischemic cortex. ATX did not alter physiological parameters, such as body temperature, brain temperature, cerebral blood flow, blood gases, blood pressure, and pH. Collectively, our data suggest that ATX can reduce ischemia-related injury in brain tissue through the inhibition of oxidative stress, reduction of glutamate release, and antiapoptosis. ATX may be clinically useful for patients vulnerable or prone to ischemic events.

Glial aromatization increases the expression of bone morphogenetic protein-2 in the injured zebra finch brain

In songbirds, brain injury upregulates glial aromatase. The resulting local estrogen synthesis mitigates apoptosis and enhances cytogenesis by poorly understood mechanisms. Bone morphogenetic proteins (BMPs), long studied for their role in neural development, are also neuroprotective and cytogenic in the adult brain. BMPs remain uncharacterized in songbirds, as do the mechanisms regulating their post-injury expression. We first established the expression of BMPs 2, 4, 6, and 7 in the adult zebra finch brain using RT-PCR. Next, we determined the effect of neural insult on BMP expression, by comparing BMP transcripts between injured and uninjured telencephalic hemispheres using semi-quantitative PCR. The expression of BMPs 2 and 4, but not 6 and 7, increased 24 h post-injury. To determine the influence of aromatase on BMP expression, we compared BMP expression following delivery of the aromatase inhibitor Fadrozole or vehicle into contralateral hemispheres. Fadrozole decreased BMP2, but not BMP4, expression, suggesting that aromatization may induce BMP2 expression following injury. Since BMPs are gliogenic and neurotrophic, future studies will test if the neuroprotective and cytogenic effects of aromatase upregulation are mediated by BMP2. Songbirds may be excellent models towards understanding the role of local estrogen synthesis and its downstream mechanisms on neuroprotection and repair.

BMP7 reduces synergistic injury induced by methamphetamine and ischemia in mouse brain

Previous studies have indicated that methamphetamine (MA) potentiates neurodegeneration induced by ischemia in brain. We, and others, have reported that bone morphogenetic protein 7 (BMP7) is protective against MA and ischemic brain injury. The purpose of this study is to examine whether BMP7 reduces synergistic injury induced by both MA and cerebral ischemia. Adult CD-1 mice were treated with MA (4x 10mg/kg, each dose 2h apart) or saline. Using the quantitative real time polymerase chain reaction, we found that MA suppressed the expression of BMP7 mRNA in the cerebral cortex 1 day after injection. Ischemic and reperfusional injuries were introduced by ligation of the right middle cerebral artery for 90min after MA injection. Animals were sacrificed for caspase-3/7 activity assay and tri-phenyl-tetrazolium chloride staining at 1h and 2 days after reperfusion, respectively. Cerebral infarction and caspase-3/7 activity were enhanced in the stroke animals pretreated with MA; both responses were attenuated by pretreatment with BMP7. In conclusion, our data suggest that MA facilitates cerebral infarction after ischemia possibly mediated, in part, through the suppression of BMP7.

A potential role for bone morphogenetic protein signalling in glial cell fate determination following adult central nervous system injury in vivo

Bone morphogenetic proteins (BMPs) and their endogenous inhibitors, including noggin, chordin and follistatin, have roles in pattern formation and fate specification of neuronal and glial cells during nervous system development. We have examined their influence on glial reactions in the injured central nervous system (CNS). We show that penetrating injuries to the brain and spinal cord resulted in the upregulation of BMP-2/4, BMP-7, and noggin, with the latter being expressed almost exclusively by reactive astrocytes at the injury site, and we show that astrocytes in vitro produce noggin. As BMPs have been shown to drive cultured NG2-positive oligodendrocyte precursors (OPCs) towards a multipotential phenotype (type II astrocytes), we investigated the effects of inhibiting noggin with a function-blocking antibody (noggin-FbAb). In vitro, BMP-driven conversion of OPCs to type 2 astrocytes was inhibited by noggin, an effect that was reversed by noggin-FbAb. Noggin-FbAb also increased the number of type 2 astrocytes generated from cultured OPCs exposed to an astrocyte feeder layer, consistent with astrocytes producing both BMPs and noggin. In knife cut injuries in vivo, noggin-FbAb treatment resulted in an increase in the number of NG2-positive cells and small GFAP-positive cells in the injury site, and the appearance of glial cells with the morphological and antigenic characteristics of type 2 astrocytes (as generated in vitro), with coexpression of both GFAP and NG2. This potential conversion of inhibitory OPCs to type 2 astrocyte-like cells in vivo suggests that endogenous BMPs, unmasked by noggin antagonism, might be exploited to manipulate cell fate following CNS trauma.

Bone morphogenetic protein-7 reduces toxicity induced by high doses of methamphetamine in rodents

Methamphetamine (MA) is a drug of abuse as well as a dopaminergic neurotoxin. We have previously demonstrated that pretreatment with bone morphogenetic protein 7 (BMP7) reduced 6-hydroxydopamine-mediated neurodegeneration in a rodent model of Parkinson's disease. In this study, we examined the neuroprotective effects of BMP7 against MA-mediated toxicity in dopaminergic neurons. Primary dopaminergic neurons, prepared from rat embryonic ventral mesencephalic tissue, were treated with MA. High doses of MA decreased tyrosine hydroxylase immunoreactivity (THir) while increasing terminal deoxynucleotidyl transferase-mediated dNTP nick end labeling. These toxicities were significantly antagonized by BMP7. Interaction of BMP7 and MA in vivo was first examined in CD1 mice. High doses of MA (10 mg/kgx4 s.c.) significantly reduced locomotor activity and THir in striatum. I.c.v. administration of BMP7 antagonized these changes. In BMP7 +/- mice, MA suppressed locomotor activity and reduced TH immunoreactivity in nigra reticulata to a greater degree than in wild type BMP7 +/+ mice, suggesting that deficiency in BMP7 expression increases vulnerability to MA insults. Since BMP7 +/- mice also carry a LacZ-expressing reporter allele at the BMP7 locus, the expression of BMP7 was indirectly measured through the enzymatic activity of beta-galactosidase (beta-gal) in BMP7 +/- mice. High doses of MA significantly suppressed beta-gal activity in striatum, suggesting that MA may inhibit BMP7 expression at the terminals of the nigrostriatal pathway. A similar effect was also found in CD1 mice in that high doses of MA suppressed BMP7 mRNA expression in nigra. In conclusion, our data indicate that MA can cause lesioning in the nigrostriatal dopaminergic terminals and that BMP7 is protective against MA-mediated neurotoxicity in central dopaminergic neurons.

Protective effect of bone morphogenetic protein-6 on neurons from H2O2 injury

Bone morphogenetic protein-6 (BMP6) is a member of the TGF-beta superfamily. Expression of BMP6 and its receptors are increased when brain tissues of adult rats are injured, suggesting that BMP6 may have a neuroprotective function in the physiologic response to neurological damage. This research investigates the molecular mechanisms supporting a neuroprotective effect of BMP6 in neural cells traumatized by H(2)O(2). We demonstrate that presence of BMP6 either before or after H(2)O(2)-induced injury protects the cultured primary cortical cells from apoptosis. However, molecular mechanisms mediating the protective effects of either pre- or post-treatment with BMP6 are different. Cells pre-treated with BMP6 have attenuated MAPK activity induced by H(2)O(2), whereas the MAPK activity in cells post-treated with BMP6 remains unchanged. Further, pharmacological inhibitors of MAPKs, PD98059 and SB203580, block the protective effect of BMP6 in the cells pre-treated with BMP6 but not in the cells post-treated with BMP6. The protective effect of post-treatment with BMP6 appears to be mediated through regulation of p53 and Bax molecules, evidenced by decreased mRNA levels after BMP6 treatment. Taken together, these data suggest BMP6 protect cortical cells against oxidation stress induced by H(2)O(2) via two different mechanisms, where (1) pre-treatment with BMP6 acts through MAPK pathway and (2) post-treatment with BMP6 works by down-regulating p53 and Bax.

Spinally upregulated noggin suppresses axonal and dendritic plasticity following dorsal rhizotomy

Bone morphogenetic proteins (BMPs) and their antagonists, including noggin, are required for nervous system development, but their potential roles in the reactions of the adult central nervous system to injury are unknown. Here we have examined the expression of noggin and BMPs in the spinal cord following dorsal rhizotomy. Through the use of a function-blocking antibody, we have also investigated the role of endogenous noggin in the neuritic plasticity which follows rhizotomy. Dorsal rhizotomy resulted in the upregulation of BMPs 2/4, 7 and noggin in the superficial white matter and in the dorsal neuropil of the spinal cord. These co-localized with glial fibrillary acidic protein, indicating their expression by astrocytes. Because BMPs induce dendritic sprouting and synaptogenesis in some neuronal populations in vitro, we hypothesized that administration of a noggin function-blocking antibody (FbAb) in vivo would augment rhizotomy-induced sprouting in the spinal cord. Topical application of noggin-FbAb to the dorsal surface of the spinal cord following rhizotomy resulted in significant increases in the density of microtubule-associated protein 2 (MAP-2) and substance P (SP)-positive processes within the lateral spinal nucleus. In the deafferented dorsal horn, noggin-FbAb treatment induced significant increases in the density of SP, calcitonin gene-related peptide (CGRP)- and 5-hydroxytryptamine (5-HT)-positive axons. These results suggest a novel mechanism by which endogenous plasticity of spared axons is suppressed following dorsal rhizotomy, and which might be exploited to improve the outcome of spinal cord injury and other CNS trauma.

Bone morphogenetic protein-4 enhances vascular endothelial growth factor secretion by human retinal pigment epithelial cells

Retinal pigment epithelial (RPE) cells secrete vascular endothelial growth factor (VEGF), a cytokine known to promote angiogenesis. Results from RNase protection assays (RPAs) show that RPE from non-diabetic human donors and from adult retinal pigment epithelium-19 (ARPE-19) cells expressed significant bone morphogenetic protein-4 (BMP-4) message. In addition, ARPE-19 cells cultured in high glucose (25 mM), compared to those in physiological glucose (5.5 mM) released significantly more BMP-4 into the conditioned media (CM). However, the effect of BMP-4 on the release of VEGF by ARPE-19 cells has not been studied. Accordingly, ARPE-19 cells were treated with BMP-4 to determine VEGF secretion. BMP-4 and VEGF levels in the CM and cell lysates were measured by enzyme-linked immunosorbent assay (ELISA). Cells treated with exogenous BMP-4 had higher VEGF in the CM and this treatment effect was dose- and time-dependent, while cell lysates had low levels of VEGF. Addition of cycloheximide (CHX) or actinomycin-D (ACT) significantly reduced VEGF secretion from cells treated with BMP-4, suggesting that the BMP-4-induced secretion of VEGF requires new RNA and protein synthesis. Our results suggest that BMP-4 may play a role in the regulation of ocular angiogenesis associated with diabetic retinopathy (DR) by stimulating VEGF release from RPE cells.

Bone morphogenetic proteins and growth differentiation factors as drug targets in cardiovascular and metabolic disease

Bone morphogenetic proteins (BMPs) and growth differentiation factors (GDFs) control the development and homeostasis of multiple tissue types in many organisms, from humans to invertebrates. These morphogens are expressed in a tissue-specific manner and they signal by binding to serine-threonine kinase receptors, resulting in coordinated changes in gene expression that regulate the differentiation and development of multiple tissue types. In addition, these proteins are regulated post-transcriptionally through binding to several soluble proteins. In this review we focus on a subset of BMPs and GDFs that have been implicated in the pathophysiology of type 2 diabetes and cardiovascular disease.

Genetically modified bone morphogenetic protein signalling Alters traumatic brain injury-induced gene expression responses in the adult mouse

Three genetic mouse models were examined to define effects of bone morphogenetic protein (BMP) signalling on gene expression in normal and injured adult brain. CaMKII-Cre eliminated the BMP receptor Acvr1 (Alk2) and the common TGFbeta superfamily signal mediator Smad4 or activated a constitutively active Acvr1 in postnatal forebrain neurons. All mutants followed mendelian ratios, with no overt phenotypic changes. In situ hybridization demonstrated normal patterns of the dendritic marker MAP2 (Mtap2) throughout cortex despite neuron-specific losses of Acvr1 or Smad4. However, strong up-regulation of Mtap2 transcript in these mice was found by quantitative RT-PCR (qRT-PCR), indicating that Mtap2 is normally suppressed by BMP. Traumatic brain injury (TBI) resulted in increases of histone-associated DNA fragments in both control and Smad4-deficient cortex. Several cell-type-specific transcripts known to be involved in injury-related responses were measured by qRT-PCR. Gfap mRNA was strongly up-regulated in controls as well as in the loss-of-BMP-signalling mutants. Notably, activated Acvr1 signalling gave significantly lower TBI-induced up-regulations of Gfap and Phox2a mRNA levels, indicating reductions in astroglial and neuronal reactions to injury. Strong impairment in injury-induced Timp1 transcript up-regulation was also seen in these mice. In contrast, osteopontin (Spp1) transcript levels in activated microglia were not reduced by Acvr1 signalling. Altogether, the data suggest that BMP signalling is dispensable in adult cortical neurons but that augmented BMP signalling affects molecular changes associated with neuronal lesions.

Neuroregenerative effects of BMP7 after stroke in rats

Previous reports have indicated that the expression of bone morphogenetic protein-7 (BMP7) is enhanced after ischemic injury in brain. This upregulation may induce endogenous neurorepair in the ischemic brain. The purpose of this study was to examine neuroregenerative effects of BMP7 after ischemia-reperfusion injury. Adult Sprague-Dawley rats were anesthetized with chloral hydrate. Right middle cerebral artery (MCA) was transiently ligated with 10-O suture for 1 h. One day after MCA occlusion, vehicle or BMP7 was infused to the contralateral cerebral ventricle. To identify possible neurogenesis, bromodeoxyurindine (BrdU) was systemically injected on the fourth and fifth days after MCA occlusion. Animals treated with BMP7 showed a rapid correction of body asymmetry and neurological deficits, suggesting BMP7 facilitates recovery after stroke. Animals were sacrificed at 1 month after stroke and brains were analyzed using immunohistological techniques. BMP7 treatment enhanced immunoreactivity of BrdU in the subventricular zone, lesioned cortex, and corpus callosum. These BrdU-positive cells co-labeled with nestin and NeuN. Our behavioral and anatomical data suggest that BMP7 promotes neuroregeneration in stroke animals, possibly through the proliferation of new neuronal precursors after ischemia.

Bone morphogenetic protein 9 induces the transcriptome of basal forebrain cholinergic neurons

Basal forebrain cholinergic neurons (BFCN) participate in processes of learning, memory, and attention. Little is known about the genes expressed by BFCN and the extracellular signals that control their expression. Previous studies showed that bone morphogenetic protein (BMP) 9 induces and maintains the cholinergic phenotype of embryonic BFCN. We measured gene expression patterns in septal cultures of embryonic day 14 mice and rats grown in the presence or absence of BMP9 by using species-specific microarrays and validated the RNA expression data of selected genes by immunoblot and immunocytochemistry analysis of their protein products. BMP9 enhanced the expression of multiple genes in a time-dependent and, in most cases, reversible manner. The set of BMP9-responsive genes was concordant between mouse and rat and included genes encoding cell-cycle/growth control proteins, transcription factors, signal transduction molecules, extracellular matrix, and adhesion molecules, enzymes, transporters, and chaperonins. BMP9 induced the p75 neurotrophin receptor (NGFR), a marker of BFCN, and Cntf and Serpinf1, two trophic factors for cholinergic neurons, suggesting that BMP9 creates a trophic environment for BFCN. To determine whether the genes induced by BMP9 in culture were constituents of the BFCN transcriptome, we purified BFCN from embryonic day 18 mouse septum by using fluorescence-activated cell sorting of NGFR(+) cells and profiled mRNA expression of these and NGFR(-) cells. Approximately 30% of genes induced by BMP9 in vitro were overexpressed in purified BFCN, indicating that they belong to the BFCN transcriptome in situ and suggesting that BMP signaling contributes to maturation of BFCN in vivo.

Transplantation of carotid body cells in the treatment of neurological disorders

Laboratory and clinical studies have shown that intracerebral transplantation of carotid body (CB) cells ameliorate Parkinsonian deficits. The recent clinical study by Arjona and colleagues indicated that CB autograft transplantation is a relatively simple, safe, and viable treatment for PD patients. In particular, Espejo and colleagues demonstrated that the therapeutic efficacy of intracerebral transplantation of the CB in PD was likely obtained through secretion of neurotrophic factors rather than the local release of dopamine, which suggests it possible and reasonable to extend the use of the CB as an efficacious graft source for neural transplantation. Thus, we transplanted CB cell suspensions into the ischemic penumbra within 1h after stroke surgery. The results revealed that CB transplantation also significantly reduced stroke-induced behavioral deficits and cerebral infarction. In this review, we focus on summarizing the physiological properties of the CB related to transplantation, describing briefly possible mechanisms responsible for the effect of CB transplantation, and introducing recent studies of the CB as a donor source for neural transplantation.

Stroke and TGF-beta proteins: glial cell line-derived neurotrophic factor and bone morphogenetic protein

Recent studies have indicated that proteins in the transforming growth factor-beta superfamily alter damage induced by various neuronal injuries. Of these proteins, glial cell line-derived neurotrophic factor (GDNF) and bone morphogenetic protein-7 (BMP-7) have unique protective and regenerative effects in stroke animals. Delivery of GDNF or BMP-7 to brain tissue reduced cerebral infarction and improved motor functions in stroke animals. Pretreatment with these factors reduced caspase-3 activity and DNA fragmentation in the ischemic brain region, suggesting that antiapoptotic effects are involved. Beside the protective effects, BMP-7 given after stroke improves locomotor function. These regenerative effects of BMP-7 may involve the enhancement of dendritic growth and remodeling. In this review, we illustrate the neuroprotective and neuroregenerative properties of GDNF and BMP-7 and emphasize their therapeutic potential for stroke.

Neurotrophic effects of bone morphogenetic protein-7 in a rat model of Parkinson's disease

Previous studies have demonstrated that pretreatment with bone morphogenetic protein-7 (BMP7) reduces ischemic neuronal injury in vivo. Moreover, exogenous application of BMP7 increases both the number of tyrosine hydroxylase (+) cells and dopamine (DA) uptake in rat mesencephalic cell cultures. The purpose of this study was to investigate the in vivo effects of BMP7 on 6-hydroxydopamine (6-OHDA) induced lesioning of midbrain DA neurons. Adult Fischer 344 rats were anesthetized and injected with BMP7 or vehicle into the left substantia nigra, followed by local administration of 9 microg of 6-OHDA into the left medial forebrain bundle. The lesioned animals that received BMP7 pretreatment, as compared to vehicle/6-OHDA controls, had a significant reduction in methamphetamine-induced rotation 1 month after the surgery. BMP7-pretreatment partially preserved KCl-induced dopamine release in the lesioned striatum and significantly increased TH immunoreactivity in the lesioned nigra and striatum. In summary, our data suggest that BMP7 has neuroprotective and/or neuroreparative effects against 6-OHDA lesioning of the nigrostriatal DA pathway in an animal model of Parkinson's disease (PD).

Intracerebral transplantation of carotid body in rats with transient middle cerebral artery occlusion

Recent laboratory and clinical studies demonstrate therapeutic efficacy of intracerebral transplantation of carotid body (CB) in Parkinson's disease, possibly through secretion of neurotrophic factors. Here, we examined the role of CB in experimental stroke. In the first experiment, we hypothesized that removal of CB would exacerbate cerebral infarction and stroke-related behavioral deficits. Eight-week-old, male Sprague-Dawley rats were randomly divided into two groups: stroke with intact CB and stroke with surgically removed CB. We used the stroke model of temporary middle cerebral artery occlusion. The ipsilateral CB was removed in animals assigned to treatment group exposed to stroke with surgically removed CB. Behavioral tests, using the elevated body swing test, were conducted at days 1-3 after surgery. Cerebral infarction was visualized by TTC staining on day 3 post-surgery. The data revealed no significant differences in behavioral deficits and infarct volumes between the two groups. In the second experiment, CB cell suspension grafts or control adult tissue grafts were intracerebally transplanted into the ischemic penumbra immediately (within 1 h) after stroke surgery. The results revealed significant reduction of behavioral deficits and infarct volumes, accompanied by increased levels of neurotrophic factors, as detected by ELISA, in transplanted ischemic striatum collected from CB-grafted stroke animals. These observations suggest that surgical resection of CB in the periphery did not alter stroke pathology; however, CB when made available in the CNS, via intracerebral transplantation, could protect against stroke possibly through the synergistic release of neurotrophic factors. The present study extends the use of CB as efficacious graft source for transplantation.

Mediation of BMP7 neuroprotection by MAPK and PKC IN rat primary cortical cultures

We have previously demonstrated that pretreatment with bone morphogenetic protein 7 (BMP7), a trophic factor in the TGFbeta superfamily, reduces ischemia-induced brain infarction induced by middle cerebral artery ligation in rats. Since the mitogen-activated protein kinase (MAPK) pathway is involved in many TGFbeta-mediated responses, we examined the interaction of BMP7 and MAPK in primary cultures obtained from the cerebral cortex of E16-17 rat embryos. Lactate dehydrogenase (LDH) in the media was used as an index of cell death. BMP7 did not alter LDH levels at low concentration (1.25 nM), but exhibited increased cellular toxicity at higher concentration (>12.5 nM). BMP7 at the low concentration significantly attenuated H2O2-induced increases in LDH activity and decreases in neuronal density. Pharmacological interactions were used to examine if MAPK was involved in this response. BMP7-induced protection was antagonized by the p42,44 MAPK kinase inhibitors PD98059 and U0125. The p38 MAPK antagonist SB203580, and their inactive analog SB202474, also attenuated BMP7-induced protection, suggesting that the interaction with p38 MAPK is nonspecific. Previous studies have indicated that SB202474 has inhibitory effects on other protein kinases. We found that the protein kinase C inhibitor chelerythrine antagonized BMP7-induced protection against H2O2. Western blot analysis indicated that BMP7 increased phosphorylation of p42,44 MAPK and PKC. Taken together, our data suggest that BMP7 is neuroprotective at low concentrations in primary cortical cell culture. The protective effects of BMP7 may involve the activation of p42,44 MAPK and PKC.

Diadenosine tetraphosphate protects against injuries induced by ischemia and 6-hydroxydopamine in rat brain

Diadenosine tetraphosphate (AP4A), an endogenous diadenosine polyphosphate, reduces ischemic injury in the heart. In this study, we report the potent and protective effects of AP4A in rodent models of stroke and Parkinson's disease. AP4A, given intracerebroventricularly before middle cerebral artery (MCA) ligation, reduced cerebral infarction size and enhanced locomotor activity in adult rats. The intravenous administration of AP4A also induced protection when given early after MCA ligation. AP4A suppressed terminal deoxynucleotidyl transferase-mediated biotinylated UTP nick end labeling (TUNEL) induced by hypoxia/reperfusion in primary cortical cultures, and reduced both ischemia-induced translocation of mitochondrial cytochrome c and the increase in cytoplasmic caspase-3 activity in vivo. The purinergic P2/P4 antagonist di-inosine pentaphosphate or P1-receptor antagonist sulfonylphenyl theophylline, but not the P2-receptor antagonist suramin, antagonized the effect of AP4A, suggesting that the observed protection is mediated through an anti-apoptotic mechanism and the activation of P1- and P4-purinergic receptors. AP4A also afforded protection from toxicity induced by unilateral medial forebrain bundle injection of 6-hydroxydopamine (6-OHDA). One month after lesioning, vehicle-treated rats exhibited amphetamine-induced rotation. Minimal tyrosine hydroxylase immunoreactivity was detected in the lesioned nigra or striatum. No KCl-induced dopamine release was found in the lesioned striatum. All of these indices of dopaminergic degeneration were attenuated by pretreatment with AP4A. In addition, AP4A reduced TUNEL in the lesioned nigra 2 d after 6-OHDA administration. Collectively, our data suggest that AP4A is protective against neuronal injuries induced by ischemia or 6-OHDA through the inhibition of apoptosis. We propose that AP4A may be a potentially useful target molecule in the therapy of stroke and Parkinson's disease.