Adenovirus-mediated gene transfer in vivo to cerebral blood vessels and perivascular tissue

Gene transfer to blood vessels in vivo generally requires interruption of blood flow. Thus, gene transduction to cerebral blood vessels in vivo has not yet been achieved. In this study, we injected replication-deficient adenovirus into cerebrospinal fluid in an attempt to transduce genes to cerebral blood vessels. Recombinant adenovirus (1 x 10(9) infectious units) expressing nuclear-targeted bacterial beta-galactosidase driven by the cytomegalovirus promoter was injected into the cisterna magna of Sprague-Dawley rats. The brains were examined histochemically after staining with 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside 1 to 7 days after injection of adenovirus. Leptomeningeal cells overlying the major arteries were efficiently transduced, and adventitial cells of large vessels and smooth muscle cells of small vessels were occasionally stained. beta-Galactosidase was expressed on days 1 and 3 after injection but was undetectable by day 7. Expression of the gene was 'targeted' by altering the position of the head. When viral suspension was injected while the rat was in a nose-down position, the reporter gene was expressed extensively on the ventral surface of the brain, especially along the circle of Willis. When the position was changed to the nose-up or lateral position, the inferior or lateral region of the brain was stained primarily. Administration of the virus into the lateral ventricle provided extensive expression in ependymal cells and leptomeninges with some transduction to cerebral blood vessels. Thus, adenovirus injected into cerebrospinal fluid provides gene transfer in vivo to cerebral blood vessels and, with greater efficiency, to perivascular tissue. Furthermore, cisternal delivery may target specific brain regions by positioning of the head.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenovirus-mediated gene transfer to normal and atherosclerotic arteries. A novel approach

Previous studies of gene transfer to blood vessels in vivo have relied on intraluminal, catheter-based methods for delivery of adenoviral and other vectors. In this study, topical application of a replication-deficient adenoviral vector was used as an alternative method of gene transfer to the vessel wall. We administered recombinant adenovirus (1.0 x 1.5 x 10(10) pfu/mL) containing the nuclear targeted bacterial beta-galactosidase gene topically to arteries in normal and atherosclerotic cynomolgus monkeys. Topical administration was achieved by injection of adenoviral suspension within the periarterial sheath. Segments of femoral and carotid arteries were examined histochemically after staining with 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside 1 day after treatment with the adenovirus. After topical administration of virus, beta-galactosidase activity was observed in approximately 20% of cells in the adventitia in both normal and atherosclerotic arteries. There was no detectable beta-galactosidase activity in cells of the intima or media. Thus, topical application provides an alternative method for gene transfer to blood vessels in vivo. This approach, which does not require interruption of blood flow and does not disrupt the endothelium, may be useful for studies of vascular biology and perhaps gene therapy in both normal and atherosclerotic vessels.

Altered vascular function after adenovirus-mediated overexpression of endothelial nitric oxide synthase

Gene transfer with replication-deficient adenovirus is a potentially useful tool to study vascular biology. We have constructed a replication-deficient adenovirus (AdRSVeNOS) that carries cDNA for endothelial nitric oxide synthase (eNOS). Transfection of COS-1 cells with AdRSVeNOS increased nitric oxide synthase activity (measured as production of L-citrulline from L-arginine) that was calcium dependent and inhibited by N omega-nitro-L-arginine methyl ester. To investigate effects of overexpression of eNOS on vascular function, we incubated common carotid arteries from rabbits in organ culture with AdRSVeNOS or AdRSV beta gal encoding beta-galactosidase. Transgene expression and responses to vasoactive agents were examined 1 day after transduction. Histochemical staining of beta-galactosidase and immunohistochemistry for eNOS indicated transgene expression in endothelium and adventitial cells. After precontraction with phenylephrine, vessels treated with AdRSVeNOS demonstrated greater relaxation to acetylcholine than vessels treated with vehicle or AdRSV beta gal. Relaxation to calcium ionophore A-23187 was much greater in vessels treated with AdRSVeNOS than in vessels treated with vehicle or AdRSV beta gal. Augmented relaxation in response to A-23187 was also observed after denudation of endothelium in vessels treated with AdRSVeNOS and was inhibited by N omega-nitro-L-arginine. Thus vasorelaxation in response to stimuli that release nitric oxide is augmented after adenovirus-mediated overexpression of eNOS. Transgene expression in adventitial cells appears to be sufficient to alter vasomotor function.

Deterioration of pre-existing hemiparesis brought about by subsequent ipsilateral lacunar infarction

Mechanisms of post-stroke recovery are still poorly understood. Recent evidence suggests that cortical reorganisation in the unaffected hemisphere plays an important role. A 59 year old man developed a small lacunar infarct in the left corona radiata, which then caused marked deterioration in a pre-existing left hemiparesis that had resulted from an earlier right putaminal haemorrhage. Functional magnetic resonance imaging showed that the paretic left hand grip activated the ipsilateral left motor areas, but not the right hemispheric motor areas. This suggests that partial recovery of the left hemiparesis had been brought about by cortical reorganisation of the left hemisphere and intensification of the uncrossed corticospinal tract. The subsequent small infarct may have damaged the uncrossed tract, thereby causing the pre-existing hemiparesis to deteriorate even further.

Adenovirus-mediated gene transfer in vivo to cerebral blood vessels and perivascular tissue in mice

BACKGROUND AND PURPOSE

Gene transfer to cerebral blood vessels has been accomplished in rats and dogs by injection of replication-deficient adenovirus into cerebrospinal fluid. In this study we examined transgene expression after injection of adenovirus into the cerebrospinal fluid of mice. Responses were observed in ICR mice and C57BL/6 mice, which are outbred and inbred strains, respectively.

METHODS

We injected replication-deficient recombinant adenovirus expressing nuclear targeted beta-galactosidase, driven by either the Rous sarcoma virus promoter (AdRSV-betaGal) or the cytomegalovirus promoter (AdCMV-betaGal), into the cisterna magna of anesthetized ICR and C57BL/6 strains of mice. The brains were examined from 1 to 21 days after injection by chemiluminescent enzyme activity assay or histochemical staining.

RESULTS

After injection of AdRSV-betaGal, expression of beta-galactosidase in ICR mice peaked on day 7 and returned to basal by day 14. Expression of beta-galactosidase in C57BL/6 mice was maximal on days 7 to 14 and was minimal by day 21 after injection of AdRSV-betaGal. After injection of AdCMV-betaGal in C57BL/6 mice, peak expression of transgene occurred on day 1 and was greatly diminished by day 3. Transgene expression was observed primarily on the ventral surface of the brain, with preferential expression in leptomeninges and adventitia along the major cerebral arteries of that region.

CONCLUSIONS

Injection of recombinant adenovirus in the cisterna magna resulted in transgene expression in leptomeninges and perivascular tissue of cerebral blood vessels in two strains of mice. The CMV promoter elicited rapid but short-lived expression of the transgene, while the RSV promoter elicited slower, more sustained transgene expression. Expression of AdRSV transgene was prolonged in C57BL/6 mice compared with ICR mice. This approach for gene transfer may be useful to study cerebral vascular biology in genetically altered strains of mice.

Age-related vulnerability to cerebral ischemia in spontaneously hypertensive rats

BACKGROUND AND PURPOSE

We sought to determine the effects of aging on regional cerebral blood flow and ischemic brain damage in transient cerebral ischemia in rats.

METHODS

Five adult (5-6 months) and five aged (18-22 months) female spontaneously hypertensive rats were subjected to 20 minutes of bilateral carotid occlusion and 60 minutes of recirculation under amobarbital anesthesia (100 mg/kg i.p.). Regional cerebral blood flow in the hippocampus and striatum was measured using the hydrogen clearance method. Nine adult and 14 aged rats were subjected to 20 minutes of bilateral carotid occlusion or were sham-operated under ether anesthesia. Seven days after 20 minutes of cerebral ischemia, the rats' brains were perfusion fixed. Ischemic damage in the hippocampus and striatum was graded (0 [normal] to 3 [majority of neurons damaged]).

RESULTS

After 20 minutes of bilateral carotid occlusion, striatal cerebral blood flow decreased to 9.1 +/- 1.5 and 3.9 +/- 2.0 ml/100 g/min in aged and adult rats, respectively, and hippocampal cerebral blood flow decreased to 8.6 +/- 2.4 and 5.7 +/- 2.4 in aged and adult rats, respectively. Although these ischemic cerebral blood flow values were not significantly different between the two age groups, scores for ischemic damage in the hippocampus CA-1 subfield and striatum were significantly higher in aged than in adult rats (p less than 0.05, Kruskal-Wallis' h test with Bonferroni correction).

CONCLUSIONS

We conclude that aging may be a primary factor in the development of greater ischemic neuronal damage observed in aged hypertensive rats.

Phosphate binders prevent phosphate-induced cellular senescence of vascular smooth muscle cells and vascular calcification in a modified, adenine-based uremic rat model

Clinical and experimental studies have reported that phosphate overload plays a central role in the pathogenesis of vascular calcification in chronic kidney disease. However, it remains undetermined whether phosphate induces cellular senescence during vascular calcification. We established a modified uremic rat model induced by a diet containing 0.3% adenine that showed more slowly progressive kidney failure, more robust vascular calcification, and longer survival than the conventional model (0.75% adenine). To determine the effect of phosphate on senescence of vascular smooth muscle cells (VSMCs) and the protective effect of phosphate binders, rats were divided into four groups: (1) normal control rats; (2) rats fed with the modified adenine-based diet (CKD); (3) CKD rats treated with 6% lanthanum carbonate (CKD-LaC); and (4) CKD rats treated with 6% calcium carbonate (CKD-CaC). After 8 weeks, CKD rats showed circumferential arterial medial calcification, which was inhibited in CKD-LaC and CKD-CaC rats. CKD rats showed increased protein expression of senescence-associated β-galactosidase, bone-related proteins, p16 and p21, and increased oxidative stress levels in the calcified area, which were inhibited by both phosphate binders. However, serum levels of oxidative stress and inflammatory markers, serum fibroblast growth factor 23, and aortic calcium content in CKD-CaC rats were higher than those in CKD-LaC rats. In conclusion, phosphate induces cellular senescence of VSMCs in the modified uremic rat model, and phosphate binders can prevent both cellular senescence and calcification of VSMCs via phosphate unloading. Our modified adenine-based uremic rat model is useful for evaluating uremia-related complications, including vascular calcification.

Gene transfer to cerebral blood vessels after subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Vasospasm remains a major cause of morbidity and mortality after aneurysmal subarachnoid hemorrhage. One step toward gene therapy to prevent spasm of cerebral vessels is to determine whether subarachnoid blood prevents transgene expression.

METHODS

Vasospasm was induced in mongrel dogs using the double-hemorrhage intracranial-injection model. Diameter of the basilar artery was assessed by angiography, and profound vasospasm (> 50% decrease in diameter) was demonstrated at 4 and 7 days. Recombinant adenovirus expressing nuclear-targeted beta-galactosidase (reporter gene) under the control of the cytomegalovirus promoter was injected into the cisterna magna at the same time as (n = 9) or 2 days after (n = 4) injection of blood for induction of vasospasm. Brains were removed and examined histochemically for expression of nuclear beta-galactosidase.

RESULTS

At 2 to 7 days, beta-galactosidase was expressed in leptomeninges over the brain stem, cortex, cerebral arteries, in small vessels in the cerebrum and brain stem, and in the ependymal lining of the ventricles. Transgene expression was observed in adventitia of blood vessels but not in vascular muscle or endothelium. Transgene expression was observed after simultaneous injection of virus and blood or when virus was injected 2 days after blood.

CONCLUSIONS

The findings indicate that intracisternal injection of recombinant adenovirus can be used for gene transfer to cerebral blood vessels and overlying meninges, even in the presence of cisternal blood. We speculate that transfer of genes using recombinant viral vectors that encode for enzymes with vasodilator function to cerebral blood vessels and perivascular tissues may be useful for prevention or treatment of cerebral vasospasm after subarachnoid hemorrhage.

Improvement of relaxation in an atherosclerotic artery by gene transfer of endothelial nitric oxide synthase

Gene transfer with replication-deficient adenovirus is a useful tool to study vascular biology. We have reported that overexpression of endothelial nitric oxide (NO) in carotid arteries from normal rabbits augments vasorelaxation mediated by NO. In this study, we tested the hypothesis that adenovirus-mediated gene transfer of endothelial nitric oxide synthase (eNOS) improves impaired relaxation of atherosclerotic vessels. We used 2 replication-deficient adenoviruses: AdeNOS, which carries cDNA for eNOS, and Adbetagal, which expresses beta-galactosidase. Common carotid arteries from 10 New Zealand White (NZW; plasma cholesterol, 79+/-13 mg/dL) and 10 Watanabe heritable hyperlipidemic (WHHL; plasma cholesterol, 452+/-39 mg/dL) rabbits were incubated in organ culture with AdeNOS, Adbetagal, or vehicle alone. Carotid arteries from WHHL rabbits had mild to moderate atherosclerotic lesions. Histochemical staining for beta-galactosidase and immunohistochemistry for eNOS indicated transgene expression in the endothelium and adventitia in both NZW and WHHL rabbits. Expression of eNOS determined with Western blot analysis after incubation with AdeNOS tended to be higher in vessels from WHHL rabbits than NZW rabbits. Effects of transgene expression on vascular function were examined by recording isometric tension 1 day after transduction. After precontraction with phenylephrine, acetylcholine produced significantly less relaxation in vessels from WHHL rabbits than in vessels from NZW rabbits. Relaxation in response to acetylcholine was greater in carotid arteries from both NZW and WHHL rabbits that were transfected with AdeNOS than in vessels treated with vehicle or Adbetagal. Vasorelaxation in response to acetylcholine was inhibited by Nomega-nitro-L-arginine. Responses to sodium nitroprusside were similar after treatment with vehicle alone, Adbetagal, or AdeNOS in both groups of rabbits. Thus, overexpression of eNOS with an adenoviral vector improves impaired NO-mediated relaxation in atherosclerotic arteries.

Hypothermia inhibits ischemia-induced efflux of amino acids and neuronal damage in the hippocampus of aged rats

Brain hypothermia has been reported to protect against ischemic damages in adult animals. Our goal in this study was to examine whether brain hypothermia attenuates ischemic neuronal damages in the hippocampus of aged animals. We also determined effects of hypothermia on ischemia-induced releases of amino acids in the hippocampus. Temperature in the hippocampus of aged rats (19-23 months) was maintained at 36 degrees C (normothermia), 33 degrees C (mild hypothermia) or 30 degrees C (moderately hypothermia) using a thermoregulator during 20 min of transient forebrain ischemia. Cerebral ischemia increased extracellular concentrations of glutamate and aspartate by 6- and 5-fold, respectively, in the normothermic group. Mild and moderate hypothermia, however, markedly inhibited the rise of these amino acids to less than 2-fold. Elevation of extracellular taurine, a putative inhibitory amino acid, was 16-fold in the normothermic rats. Mild hypothermia attenuated ischemia-induced increase in taurine (10-fold), and moderate hypothermia inhibited the increase. Ischemic damages, evaluated by histopathological grading of hippocampal CA1 area 7 days after ischemia, was significantly ameliorated in the mild (1.3+/-0.5, mean+/-S.E.M.) and moderate hypothermic rats (0.8+/-0.3) compared with the normothermic ones (3.4+/-0.4). These results suggest that brain hypothermia protects against ischemic neuronal damages even in the aged animals, and the protection is associated with inhibition of excessive effluxes of both excitatory and inhibitory amino acids.

Cationic polymer and lipids enhance adenovirus-mediated gene transfer to rabbit carotid artery

BACKGROUND AND PURPOSE

Improvement of efficiency of gene transfer to endothelium could be useful for several applications. We tested the hypothesis that cationic nonviral molecules augment adenovirus-mediated gene transfer to blood vessels, perhaps by alteration of the surface charge of adenovirus and facilitation of binding to endothelium.

METHODS

Carotid arteries from rabbits were incubated in vitro for 0.5 to 2 hours with an adenoviral vector alone or noncovalent complexes of adenovirus with poly-L-lysine (a cationic polymer) or lipofectin (a cationic lipid). Binding of adenovirus to the vessels was evaluated immediately after incubation with virus, and assay of transgene (ss-galactosidase) activity and histochemistry were performed 24 hours after gene transfer. To determine whether cationic molecules can be used to augment alteration of vascular function by adenovirus-mediated gene transfer, we also examined effects on gene transfer of endothelial nitric oxide synthase.

RESULTS

Assay of ss-galactosidase activity indicated that both cationic molecules increased transgene expression in vessels by approximately 5- to 6-fold. In contrast, when endothelium was removed from the vessels after gene transfer, poly-L-lysine and lipofectin did not significantly increase transgene activity. Histochemistry for ss-galactosidase also suggested that the adenovirus-cationic molecule complexes augmented transgene expression mainly in the endothelium. In addition, we found that complexing adenovirus with cationic molecules increased binding of adenovirus to the vessels. After gene transfer with recombinant adenovirus containing endothelial nitric oxide synthase, calcium ionophore (A23187) produced greater relaxation of vessels treated with adenovirus complexed with poly-L-lysine or lipofectin than those treated with adenovirus alone.

CONCLUSIONS

Cationic molecules improve the efficiency of adenovirus-mediated gene transfer to blood vessels.

Inhibition of ischemia-induced dopamine release by omega-conotoxin, a calcium channel blocker, in the striatum of spontaneously hypertensive rats: in vivo brain dialysis study

The effect of omega-conotoxin GVIA (CgTX), an N-and L-type voltage-sensitive calcium channel (VSCC) blocker, on the release of dopamine and 3,4-dihydroxyphenylacetic acid (DOPAC) in the striatum before and during transient cerebral ischemia in spontaneously hypertensive rats was studied using an in vivo brain dialysis technique. Continuous perfusion of CgTX in the striatum was started 20 min before ischemia and concentrations of dopamine and DOPAC in the dialysate were measured using HPLC with an electro-chemical detector. Before ischemia, both 10 and 100 microM CgTX significantly lowered the concentration of dopamine, to 49% of the basal values. DOPAC concentrations also decreased significantly, by 28 and 17%, respectively. Forebrain ischemia, produced by bilateral carotid artery occlusion, reduced striatal blood flow to less than 6% of the resting value in each group. During 20 min of ischemia, the vehicle group showed a marked increase in dopamine (175 times the basal concentration). In the 10 or 100 microM CgTX perfusion group, in contrast, dopamine release was significantly attenuated, to 38 or 29% of the vehicle group, respectively. DOPAC concentrations decreased during ischemia to 58% of the basal value in the vehicle group and 49% in both CgTX groups. These results indicate that the massive release of striatal dopamine during ischemia depends largely on the influx of extracellular calcium via CgTX-sensitive VSCCs.

Inhibition of Na+/H+ exchanger reduces infarct volume of focal cerebral ischemia in rats

Activation of Na+/H+ exchanger (NHE) may have an important role in ischemic cell death by means of intracellular overload of Na(+) and Ca(2+). Recent evidence has suggested that inhibitors of NHE have protective effects on myocardial ischemia both in vivo and in vitro. In this study, we tested the hypothesis that FR183998, an inhibitor of NHE, reduces infarct volume produced by focal cerebral ischemia in rats. We used 20 male spontaneously hypertensive rats. Either FR183998 (1 mg/kg; n=10), or vehicle (n=10) was given intravenously to the rats and the distal middle cerebral artery of each animal was occluded using a photothrombotic technique. We measured regional cerebral blood flow using laser-Doppler flowmetry throughout the experiments. After 3 days, infarct volume was measured in each animal group. To estimate the brain edema, we also calculated the cortical volume in both hemispheres. The infarct volume in the FR183998-treated group (82+/-8 mm(3), mean+/-S.E.M.) was significantly smaller than that in the control group (115+/-12 mm(3)) (P=0.034). The cortical volume of the occluded side in the FR183998-treated group (359+/-7 mm(3)) tended to be smaller than that in the control group (378+/-9 mm(3)) (P=0.116). The regional cerebral blood flow and physiological variables during ischemia were not significantly different between the two groups throughout the experiments. These results suggest that inhibition of NHE by FR183998 may have beneficial effects in reducing infarct volume and brain edema during cerebral ischemia. Thus, NHE may play an important role in the development of neuronal damage during acute cerebral ischemia.

Cerebral hemodynamics in hypertensive patients compared with normotensive volunteers. A transcranial Doppler study

BACKGROUND AND PURPOSE

The present study was designed to examine cerebral hemodynamics in early and chronic stages of hypertension using transcranial Doppler sonography.

METHODS

Our study population consisted of 16 chronic hypertensive patients with chronic and small deep brain infarction, 10 young early-stage hypertensive subjects, and 16 young normotensive healthy volunteers. Using three-dimensional mapping techniques, we identified the M1 portion of the middle cerebral arteries and measured mean blood flow velocity, and we calculated the Gosling pulsatility index (PI), Fourier PI of the first harmonic (Fourier PI1), and cerebrovascular resistance.

RESULTS

Mean blood flow velocity in the young hypertensive group was statistically higher (71.7 +/- 11.7 cm/s [mean +/- SD]) than among chronic hypertensive subjects (56.9 +/- 21.4 cm/s, P < .01) and normotensive subjects (63.2 +/- 11.8 cm/s, P < .05). Gosling PI presented a mirror image of mean blood flow velocity in both hypertensive and normotensive subjects. Chronic hypertensive subjects showed significantly higher Fourier PI1 (0.32 +/- 0.05) and cerebrovascular resistance (2.08 +/- 0.82 mm Hg/cm per second) than normotensive subjects (0.25 +/- 0.03 and 1.31 +/- 0.23 mm Hg/cm per second [P < .005], respectively) or early-stage hypertensive subjects (0.25 +/- 0.04 and 1.44 +/- 0.26 mm Hg/cm per second [P < .02], respectively).

CONCLUSIONS

Early-stage hypertensive subjects demonstrated higher velocity, normal Fourier PI1, and near normal vascular resistance, whereas chronic hypertensive subjects showed near normal velocity, higher Fourier PI, and greater vascular resistance. Results may indicate different degrees of cerebral arteriopathy and arteriolopathy between early and late stages of hypertension.

Postischemic gene transfer of midkine, a neurotrophic factor, protects against focal brain ischemia

Gene therapy may be a promising approach for treatment of brain ischemia. In this study, we examined the effect of postischemic gene transfer of midkine, a heparin-binding neurotrophic factor, using a focal brain ischemia model with the photothrombotic occlusion method. At 90 min after induction of brain ischemia in spontaneously hypertensive rats, a replication-deficient recombinant adenovirus encoding mouse midkine (AdMK, n=7) or a control vector encoding beta-galactosidase (Adbetagal, n=7) was injected into the lateral ventricle ipsilateral to ischemia. At 2 days after ischemia, we determined infarct volume by 2,3,5-triphenyltetrazolium chloride staining. There were no significant differences in cerebral blood flow 1 h after ischemia between AdMK and Adbetagal groups. Infarct volume of AdMK group was 51+/-27 mm3, which was significantly smaller than that of Adbetagal group (86+/-27 mm3, P<0.05). TUNEL-positive and cleaved caspase-3-positive cells in the periischemic area of AdMK-treated rats were significantly fewer than those in Adbetagal-treated rats, suggesting that the reduction of infarct volume by midkine was partly mediated by its antiapoptotic action. Thus, gene transfer of midkine to the ischemic brain may be effective in the treatment of brain ischemia.

Angiotensin converting enzyme inhibitors attenuate ischemic brain metabolism in hypertensive rats

BACKGROUND AND PURPOSE

Angiotensin converting enzyme (ACE) inhibitors are expected to modulate neuronal activities. The present study was designed to examine the beneficial effects of ACE inhibitors on microcirculation and metabolism in the ischemic brain.

METHODS

Cerebral ischemia was developed for 60 minutes in spontaneously hypertensive rats (SHR, n = 35) by bilateral carotid artery occlusion. ACE inhibitor (0.1 or 10 mg/kg SQ 29,852 or captopril) were intravenously injected 15 minutes before cerebral ischemia. Cerebral blood flow to the parietal cortex was measured with the H2 clearance technique. Lactate, pyruvate, and ATP in the brain were estimated by the enzymatic method.

RESULTS

Before cerebral ischemia, high doses of both SQ 29,852 and captopril significantly decreased mean arterial pressure by 15 to 25 mm Hg and reduced cerebral vascular resistance by 13% to 17% of the resting values. Cerebral blood flow and arterial pressure during ischemia were not altered by these ACE inhibitors. After 60 minutes of cerebral ischemia, tissue lactate in vehicle-treated SHR increased 6.6-fold and ATP decreased to 65% of the control values. Administration of SQ 29,852 or captopril significantly reduced the lactate levels to 1.6- to 3.1-fold and well preserved the ATP levels to 82% to 93% of the control.

CONCLUSIONS

These results suggest that inhibition of ACE activities may be protective for cerebral metabolism against ischemic insult.

Selective induction of ΔFosB in the brain after transient forebrain ischemia accompanied by an increased expression of galectin-1, and the implication of ΔFosB and galectin-1 in neuroprotection and neurogenesis

Transient forebrain ischemia causes selective induction of DeltaFosB, an AP-1 (activator protein-1) subunit, in cells within the ventricle wall or those in the dentate gyrus in the rat brain prior to neurogenesis, followed by induction of nestin, a marker for neuronal precursor cells, or galectin-1, a beta-galactoside sugar-binding lectin. The adenovirus-mediated expression of FosB or DeltaFosB induced expression of nestin, glial fibrillary acidic protein and galectin-1 in rat embryonic cortical cells. DeltaFosB-expressing cells exhibited a significantly higher survival and proliferation after the withdrawal of B27 supplement than the control or FosB-expressing cells. The decline in the DeltaFosB expression in the survivors enhanced the MAP2 expression. The expression of DeltaFosB in cells within the ventricle wall of the rat brain also resulted in an elevated expression of nestin. We therefore conclude that DeltaFosB can promote the proliferation of quiescent neuronal precursor cells, thus enhancing neurogenesis after transient forebrain ischemia.

Augmented adenovirus-mediated gene transfer to atherosclerotic vessels

Vascular endothelium is an important target for gene transfer in atherosclerosis. In this study, we examined gene transfer to normal and atherosclerotic blood vessels from two species, using an organ culture method. Using normal aorta, we determined optimal dose, duration of exposure to adenovirus, and duration of incubation of vessels in tissue culture. Aortas from normal and atherosclerotic monkeys were cut into rings and incubated for 2 hours with a recombinant adenovirus, carrying the reporter gene for beta-galactosidase driven by a cytomegalovirus (CMV) promoter. After 20 hours of incubation, transgene expression was assessed with a morphometric method after histochemical staining and a chemiluminescent assay of enzyme activity. Expression of beta-galactosidase after histochemical staining, expressed as percentage of total cells, was similar in adventitial cells of normal monkeys (21 +/- 4%, mean +/- SE%) and atherosclerotic monkeys (25 +/- 12%). Transgene expression in endothelium was higher in atherosclerotic than in normal vessel (53 +/- 3% versus 27 +/- 7%, P < .05). Chemiluminescent assay indicated greater beta-galactosidase activity (2.5 +/- 0.6 mU/mg of protein) in the intima and media of atherosclerotic than normal vessels (0.6 +/- 0.2 mU/mg of protein, P < .05). Aortas from normal (n = 6) and atherosclerotic (n = 5) rabbits also were examined. Transgene expression (after histochemical staining) in endothelium was much greater in atherosclerotic than normal rabbits (39 +/- 3% versus 9 +/- 2%, P < .05) and expression in adventitial cells was similar (normal 23 +/- 2%, atherosclerotic 24 +/- 4%). Chemiluminescent assay indicated greater beta-galactosidase activity (1.2 +/- 0.4 mU/mg of protein) in the intima and media of atherosclerotic than normal vessels (0.2 +/- 0.1 mU/mg protein, P < .05). These findings suggest that an adenoviral vector with a CMV promoter provides similar transgene expression in adventitia of both normal and atherosclerotic vessels. Gene transfer to the endothelium was much more effective in atherosclerotic than in normal vessels. Thus it may be possible to achieve greater transgene expression in atherosclerotic than in normal arteries.

Ischemia-induced release of amino acids in the hippocampus of aged hypertensive rats

We have recently demonstrated the age-related vulnerability of hippocampal neurons to 20-min forebrain ischemia in spontaneously hypertensive rats (SHR). In the present study, we investigated the effect of aging on the release of amino acids in the hippocampus during transient cerebral ischemia for 20 min. Concentrations of extracellular amino acids and cerebral blood flow in the CA1 subfield were examined by an in vivo brain dialysis technique and a hydrogen clearance method, respectively, in adult (5-7 month) and aged (19-23 month) female SHR. During cerebral ischemia by bilateral carotid artery occlusion, cerebral blood flow to the hippocampus decreased to 20% of the resting values in both groups. After recirculation, both groups showed delayed hypoperfusion which was more prominent in the aged SHR. In the adult rats, concentrations of both aspartate and glutamate increased to approximately 8-fold of the resting values during ischemia. The elevation of these excitatory amino acids in the adult SHR was not significantly different from that in the aged rats. In contrast, the concentration of taurine increased 26-fold in the adult SHR but only 16-fold in the aged rats. Changes in other amino acids were not different between the two groups. These results indicate that an imbalance of excitatory and inhibitory amino acids, e.g., smaller release of taurine, during ischemia may, at least in part, contribute to the age-related vulnerability of hippocampal neurons to transient cerebral ischemia in SHR.

Adenovirus-mediated gene transfer to ischemic brain: ischemic flow threshold for transgene expression

BACKGROUND AND PURPOSE

Gene therapy may be a promising approach for treatment of brain ischemia, although protein synthesis is generally inhibited in ischemic conditions. Our goal in this study was to examine effects of brain ischemia on transgene expression of adenovirus-mediated gene transfer to ischemic brain.

METHODS

Brain ischemia was produced by photochemical occlusion of the distal middle cerebral artery of spontaneously hypertensive rats (n=15). Ninety minutes after ischemia, adenoviral vectors encoding bacterial beta-galactosidase were injected into ipsilateral (nonischemic [I-n], peri-ischemic [I-p], and ischemic core [I-c] areas) and contralateral parietal (C) cortices. Cerebral blood flow before and during ischemia at each injected area was measured by laser-Doppler flowmetry. Expression of transgene was detected by histochemistry for semiquantitative scoring or by biochemical assay for quantitative analysis.

RESULTS

Blood flow to the cortex decreased to 72+/-10% (mean+/-SEM) at I-n, 41+/-6% at I-p, and 23+/-3% at I-c after 10 minutes of ischemia. Expression of the reporter gene was consistently detected at C and I-n at each survival period. The semiquantitative score for transgene expression decreased according to severity of ischemia (C, 2.3; I-n, 2.6; I-p, 1.1; I-c, 0.3; mean values). beta-Galactosidase activity detected by chemiluminescent assay revealed that the values (mean+/-SEM) in the ischemic area (I-p, 15.9+/-9.2 mU/mg protein; I-c, 1.3+/-0.5) were significantly smaller than that of the nonischemic area (C, 45.4+/-6.9). Analysis of cerebral blood flow at I-p revealed that cerebral blood flow threshold for transgene expression was approximately 40% of the resting value.

CONCLUSIONS

Adenovirus-mediated gene transfer into the ischemic brain provided effective expression of transgene at the nonischemic and peri-ischemic areas. Gene transfer to the ischemic brain may be a promising approach for treatment of ischemic penumbra.

Modulation of ischemia-evoked release of excitatory and inhibitory amino acids by adenosine A1 receptor agonist

Adenosine has been reported to have beneficial effects against ischemic brain damage, although the mechanisms are not fully clarified. To examine the role of adenosine on the ischemia-evoked release of neurotransmitters, we applied a highly selective agonist for adenosine A1 receptor, 2-chloro-N6-cyclopentyladenosine (CCPA), into the ischemic brain using in vivo brain dialysis, which directly delivered the agonist to the local brain area. Concentrations of extracellular amino acids (glutamate, aspartate, gamma-aminobutyric acid (GABA) and taurine) and regional blood flow in the striatum of spontaneously hypertensive rats (SHRs) were monitored during cerebral ischemia elicited by bilateral carotid artery occlusion for 40 min and recirculation. Striatal blood flow and basal levels of amino acids were not affected by direct perfusion of CCPA (10 microM or 100 microM). During ischemia, concentrations of glutamate, aspartate, GABA and taurine increased up to 37-, 30-, 96- and 31-fold, respectively, when vehicle alone was administered. Administration of CCPA did not affect the changes in regional blood flow during ischemia and reperfusion. Perfusion of CCPA (100 microM), however, significantly attenuated the ischemia-evoked release of aspartate (by 70%) and glutamate (by 73%). The ischemia-induced increase of GABA tended to be decreased by CCPA, although it was not statistically significant. In contrast, both low and high concentrations of CCPA had little effect on the release of taurine during ischemia. These results suggest that stimulation of adenosine A1 receptors selectively attenuated the ischemia-evoked release of excitatory amino acids, but not of inhibitory amino acids without affecting blood flow. This modulation of the release of amino acids by adenosine A1 receptor agonists may play a protective role against ischemic neuronal damage.

Intrapericardial administration of adenovirus for gene transfer

Gene transfer to the heart has been accomplished with intravascular administration of adenoviral vectors into the pericardial sac, by increasing the duration of exposure to the adenovirus, would result in gene expression in the pericardium and perhaps myocardium and therefore might provide an alternative method to intravascular administration for gene transfer. We injected a replication-deficient adenovirus (average 1 x 10(12) particles/ml in 3% sucrose; 1 x 10(10) plaque forming units/ml containing cDNA encoding a nuclear-targeted bacterial beta-galactosidase into the pericardial sac of dogs. Samples of the pericardium and heart were examined for enzymatic activity of beta-galactosidase and after histochemical staining with 5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside. One day after injection of the adenovirus (1-3 ml), beta-galactosidase activity was highest in the parietal pericardium and left atrial tissue and lower in the right and left ventricles. Histochemical expression of the transgene was predominantly in the visceral pericardium of atria and ventricles and occasionally in the epicardial myocytes, arterioles, and venules. Pretreatment with doxycycline (5 mg) before adenovirus administration increased transgene activity in left ventricles. Thus adenovirus injected into the pericardial sac provides an effective method for gene transfer to the visceral and parietal pericardium over atria and ventricles.

Protein kinase C modulates ischemia-induced amino acids release in the striatum of hypertensive rats

The role of protein kinase C (PKC) in mediating the ischemia-induced release of amino acids in the striatum was studied using an in vivo brain dialysis technique in the striatum of spontaneously hypertensive rats (SHRs). Using HPLC combined with fluorescence detection methods, we investigated the concentrations of amino acids in the dialysates produced by 20 min of transient forebrain ischemia. We studied the effects of an inhibitor of PKC, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H7) and another isoquinoline analog (HA1004) with less inhibitory effect on the C kinase in ischemia-induced amino acids release. Bilateral carotid artery occlusion caused a marked reduction in the striatal blood flow by 91 +/- 6%. The extent of the cerebral blood flow (CBF) reduction were essentially the same among H7-, HA1004-, and the vehicle-treated groups. Forebrain ischemia produced a marked increase in glutamate (21-fold of the basal concentration), aspartate (19-fold) and taurine (16-fold). Pretreatment with H7 markedly attenuated the ischemia-in-duced release of these three amino acids to 3, 3 and 4-fold of the basal values, respectively. Increase of gamma-aminobutyric acid (GABA) was also attenuated by H7 (vehicle; 2.46 +/- 1.26 microM, H7; 0.62 +/- 0.75 mM). HA1004 did not affect the release of glutamate, aspartate or GABA during ischemia. The ischemia-induced release of taurine was significantly inhibited by HA1004 but the effect was much smaller than that of H7. These results thus indicate that PKC plays a major role in the ischemia-induced release of amino acids in the striatum of SHR.

Effect of selective brain hypothermia on regional cerebral blood flow and tissue metabolism using brain thermo-regulator in spontaneously hypertensive rats

To investigate the effect of selective hypothermia of the brain (brain cooling) on regional cerebral blood flow and tissue metabolism, we have developed a brain thermo-regulator. Brain temperature was modulated by a water-cooled metallic plate placed on the surface of the rats' scalp to get the appropriate brain temperature precisely with ease. Regional cerebral blood flow and brain temperature were measured simultaneously using a Teflon-coated platinum electrode and thermocouple probe inserted stereotaxically into the parietal cortex and thalamus in spontaneously hypertensive rats. Experimental forebrain ischemia was induced by the occlusion of bilateral common carotid artery under normo- and hypothermic brain condition, and the supratentorial brain tissue metabolites were measured enzymatically after 60 min of forebrain ischemia. When cortical temperature was set to hypothermia, cortical blood flow was significantly lowered by 40% at 30 degree C and 20% at 33 degree C as compared with that at 36 degree C (p < 0.0001 and p < 0.05, respectively). Thalamic blood flow was also significantly reduced by 20% when cortical temperature was set to 30 degree C as compared with 36 degree C (p < 0.05). There were no significant differences in arterial blood pressure and gas parameters throughout these experiments. In the rats with selective brain hypothermia (30 degree C) immediately after the induction of cerebral ischemia, the level of brain ATP concentration after 60 min of ischemia was significantly higher than that in normothermia rats (36 degree C) (p < 0.05). Our findings indicate that: 1) the metallic plate brain thermo-regulator is useful in small animal experiments; 2) regional brain temperature regulates regional cerebral blood flow; and 3) selective brain hypothermia, even started after the forebrain ischemia, ameliorates the derangement of brain metabolism, suggesting its effectiveness as a cytoprotective strategy.

NAD(P)H oxidase p22phoxC242T polymorphism and ischemic stroke in Japan: the Fukuoka Stroke Registry and the Hisayama study

The C242T polymorphism of p22phox, a component of NAD(P)H oxidase, may have an impact on cardiovascular diseases; however, the association between this polymorphism and brain infarction is not fully understood. Here, we investigate the relationship between the C242T polymorphism and brain infarction in Japan. We recruited 1055 patients with brain infarction and 1055 control subjects. A chi-squared test revealed that the T-allele frequency was lower in patients with cardioembolic infarction (5.6%) than in control subjects (11.0%, P < 0.001); however, allele frequencies in patients with lacunar and atherothrombotic infarction (11.2%) were not significantly different from those in control subjects (11.0%). A multivariate-adjusted conditional logistic regression analysis also revealed no association between CT + TT genotype, and lacunar and atherothrombotic infarction (odds ratio = 0.97, 95% confidence interval: 0.72-1.32). To investigate the functional effects of the C242T polymorphism, we examined superoxide production in COS-7 cells cotransfected with Nox4 and p22phox of each genotype. The superoxide-producing activity in those cells expressing p22phox with the T allele was not significantly different from that in cells expressing p22phox with the C allele. The present results suggest that the p22phox C242T polymorphism may have a protective effect against cardioembolic infarction, but is not related to lacunar and atherothrombotic infarction in Japan.