Biomedical subjects

Michael Chopp

Publications and source records attributed to Michael Chopp.

At least 55 records · Page 3Linked to original sources

PubMed2006

Mass-related traumatic tissue displacement and behavior: a screen for treatments that reduce [corrected] harm to bystander cells and recovery of function.

In this study, we focused on a preclinical model of brain compression injury that has relevance to pathological conditions such as tumor, hematoma, blood clot, and intracerebral bony fragment. We investigated behavioral impairment as a result of rapid-onset small mass, and the factors involved in lesion formation and neuroplasticity. An epidural bead implantation method was adopted. Two sizes (1.5 mm and 2.0 mm thick) of hemisphere-shaped beads were used. The beads were implanted into various locations over the sensorimotor cortex (SMC--anterior, middle and posterior). The effects of early versus delayed bead removal were examined to model clinical neurosurgical or other treatment procedures. Forelimb and hind-limb behavioral deficits and recovery were observed, and histological changes were quantified to determine brain reaction to focal compression. Our results showed that the behavioral deficits of compression were influenced by the location, timing of compression release, and magnitude of compression. Even persistent compression by the thicker bead (2.0 mm) caused only minor behavioral deficits, followed by fast recovery within a week in most animals, suggesting a mild lesion pattern for this model. Brain tissue was compressed into a deformed shape under pressure with slight tissue damage, evidenced by pathological evaluation on hematoxylin and eosin (H&E)- and TUNEL-stained sections. Detectable but not severe behavioral dysfunction exhibited by this model makes it particularly suitable for direct assessment of adverse effects of interventions on neuroplasticity after brain compression injury. This model may permit development of treatment strategies to alleviate brain mass effects, without disrupting neuroplasticity.

Animals↗

PubMed2006

Long-term recovery after bone marrow stromal cell treatment of traumatic brain injury in rats.

OBJECT: This study was designed to follow the effects of bone marrow stromal cell (BMSC) administration in rats after traumatic brain injury (TBI) for a 3-month period. METHODS: Forty adult female Wistar rats were injured by a controlled cortical impact and, 1 week later, were injected intravenously with one of three different doses of BMSCs (2 x 10(6), 4 x 10(6), or 8 x 10(6) cells per animal) obtained in male rats. Control rats received phosphate-buffered saline (PBS). Neurological function in these rats was studied using a neurological severity scale (NSS). The rats were killed 3 months after injury, and immunohistochemical stains were applied to brain samples to study the distribution of the BMSCs. Additional brain samples were analyzed by quantitative enzyme-linked immunosorbent assays to measure the expression of the growth factors brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Three months after injury, BMSCs were present in the injured brain and their number was significantly greater in animals that received 4 x 10(6) or 8 x 10(6) BMSCs than in animals that received 2 x 10(6) BMSCs. The cells were primarily distributed around the lesion boundary zone. Functional outcome was significantly better in rats that received 4 x 10(6) or 8 x 10(6) BMSCs, compared with control animals, although no improvement was seen in animals that received 2 x 10(6) BMSCs. All doses of BMSCs significantly increased the expression of BDNF but not that of NGF; however, this increase was significantly larger in animals that received 4 x 10(6) or 8 x 10(6) BMSCs than in controls or animals that received 2 x 10(6) BMSCs. CONCLUSIONS: In summary, when injected in rats after TBI, BMSCs are present in the brain 3 months later and significantly improve functional outcome.

Animals↗

PubMed2006

Effects of intravenous administration of human bone marrow stromal cells after intracerebral hemorrhage in rats.

OBJECT: The goal of this study was to investigate whether human bone marrow stromal cells (hBMSCs) administered by intravenous injection have a beneficial effect on outcome after intracerebral hemorrhage (ICH) in rats. METHODS: An ICH was induced in 54 adult male Wistar rats by a stereotactically guided injection of autologous blood into the right striatum. Intravenous infusion of the hBMSCs (3, 5, or 8 million cells) was performed 1 day after ICH, and for each dose group there was a control group that received injections of vehicle. Neurological function, which was evaluated using the Neurological Severity Score (NSS) and the corner turn test, was tested before and at 1, 7, and 14 days after ICH. After 14 days of survival, the area of encephalomalacia was calculated and histochemical labeling was performed. For all three groups, there were no statistical differences in either the NSS or corner turn tests after 1 day. After 7 and 14 days, however, the three groups that received the hBMSCs showed significant improvement in functional scores compared with the control group. In addition, after 14 days there was significantly more striatal tissue loss in the placebo groups compared with each of the three treatment groups. The region of injury in the treated animals demonstrated a significantly increased presence of hBMSCs, immature neurons, neuronal migration, synaptogenesis, and newly formed DNA. CONCLUSIONS: Intravenous administration of hBMSCs significantly improves neurological function in rats subjected to ICH. This improvement in the treated animals is associated with reduced tissue loss and increased local presence of the hBMSCs, mitotic activity, immature neurons, synaptogenesis, and neuronal migration.

Animals↗

PubMed2006

Treatment of embolic stroke in rats with bortezomib and recombinant human tissue plasminogen activator.

Stroke elicits a progressive vascular dysfunction, which contributes to the evolution of brain injury. Thrombolysis with tissue plasminogen activator (tPA) promotes adverse vascular events that limit the therapeutic window of stroke to three hours. Proteasome inhibitors reduce vascular thrombotic and inflammatory events, and consequently protect vascular function. The present study evaluated the neuroprotective effect of bortezomib, a potent and selective inhibitor of the proteasome, alone and in combination with delayed thrombolytic therapy on a rat model of embolic focal cerebral ischemia. Treatment with bortezomib reduces adverse cerebrovascular events including secondary thrombosis, inflammatory responses, and blood brain barrier (BBB) disruption, and hence reduces infarct volume and neurological functional deficit when administrated within 4 h after stroke onset. Combination of bortezomib and tPA extends the thrombolytic window for stroke to 6 h, which is associated with the improvement of vascular patency and integrity. Real time RT-PCR of endothelial cells isolated by laser-capture microdissection from brain tissue and Western blot analysis showed that bortezomib upregulates endothelial nitric oxide synthase (eNOS) expression and blocks NF-kappaB activation. These results demonstrate that bortezomib promotes eNOS dependent vascular protection, and reduces NF-kappaB dependent vascular disruption, all of which may contribute to neuroprotection after stroke.

Animals↗

PubMed2005

Multitargeted effects of statin-enhanced thrombolytic therapy for stroke with recombinant human tissue-type plasminogen activator in the rat.

BACKGROUND: Microvascular dysfunction posttreatment of stroke with recombinant human tissue-type plasminogen activator (rht-PA) constrains the therapeutic window to 3 hours. Statins (3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors) promote vascular thrombolysis and reduce the inflammation response. We therefore investigated the neuroprotective effects of a combination of atorvastatin and delayed rht-PA treatment in a rat model of embolic stroke. METHODS AND RESULTS: Rats subjected to embolic middle cerebral artery occlusion were treated with atorvastatin in combination with rht-PA 4 hours after stroke. Magnetic resonance imaging measurements revealed that combination treatment with atorvastatin and rht-PA blocked the expansion of the ischemic lesion, which improved neurological function compared with saline-treated rats. Real-time reverse transcription-polymerase chain reaction analysis of single endothelial cells isolated by laser-capture microdissection from brain tissue and immunostaining showed that combination treatment downregulated expression of tissue factor, von Willebrand factor, protease-activated receptor-1, intercellular adhesion molecule-1, and matrix metalloproteinase-9, which concomitantly reduced cerebral microvascular thrombosis and enhanced microvascular integrity. Combination treatment did not increase cerebrovascular endothelial nitric oxide synthase (eNOS) levels or eNOS activity, and inhibition of NOS activity with N-nitro-L-arginine methyl ester did not block the beneficial effects of combination treatment on stroke. Furthermore, combination treatment compared with thrombolytic monotherapy increased cerebral blood flow and reduced infarct volume in eNOS-null mice. CONCLUSIONS: These data demonstrate that combination treatment with atorvastatin and rht-PA exerts a neuroprotective effect when administered 4 hours after stroke and that the therapeutic benefits are likely attributed to its multitargeted effects on cerebrovascular patency and integrity.

Animals↗

PubMed2005

A model of mini-embolic stroke offers measurements of the neurovascular unit response in the living mouse.

BACKGROUND AND PURPOSE: To measure cerebral vascular and neuronal responses after stroke in the living mouse, we generated a mouse model of embolic stroke localized to the parietal cortex. METHODS: Male C57/6J or male transgenic mice (2 to 3 months old) expressing yellow fluorescent protein (YFP) were used in the present study. A single fibrin-rich clot (8 mm in length) was injected into a branch of the right middle cerebral artery (MCA). MRI measurements were performed to measure ischemic lesion. Using confocal and 2-photon microscopy, changes in the embolus, dendrites, and dendritic spines were measured in the living mouse. RESULTS: Eight of 11 mice (73%) had the embolus localized to a branch of the right MCA in the parietal cortex. Expansion of the embolus within the artery was observed 24 hours after stroke. The presence of ischemic lesion in the parietal cortex was verified by MRI measurements, and histopathological analysis revealed that these mice (n=8) had a cortical infarct volume of 4.9+/-3.6% of the contralateral hemisphere. In the living mouse, substantial loss of YFP-labeled axonal and dendritic structures as well as the formation of abnormal dendritic bulbs were detected in the ischemic boundary regions 24 hours after stroke compared with that 1 hour after stroke. CONCLUSIONS: This model offers a novel approach to study the neurovascular unit in cerebral cortex after stroke in the living mouse.

Animals↗

PubMed2005

Biphasic effects of exogenous VEGF on VEGF expression of adult neural progenitors.

Vascular endothelial growth factor (VEGF) regulates neurogenesis. The present study investigated the direct effect of VEGF on the enhancement of proliferation and differentiation of the adult mouse subventricular zone (SVZ) neural progenitors in vitro. A high dose (500 ng/ml) of VEGF significantly downregulated endogenous VEGF receptors 1 and 2, which was associated with significantly reduced neural progenitor cell proliferation and enhancement of neuronal differentiation. A low dose (50 ng/ml) of VEGF significantly upregulated endogenous VEGF receptors 1 and 2 but did not increase proliferation and differentiation. These data suggest that exogenous VEGF has a biphasic effect on the expression of endogenous VEGF receptors, and the high dose of VEGF enhances adult neural progenitor cell differentiation into neurons.

Animals↗

PubMed2005

EphB2 induces proliferation and promotes a neuronal fate in adult subventricular neural precursor cells.

The subventricular germinal zone (SVZ) retains an active population of stem cells and neural precursor cells throughout adulthood. EphrinB signaling mediates angiogenesis and vasculogenesis in the developing and adult brain. Recent studies indicate that molecules involved in angiogenesis often influence neurogenesis as well. However, little work has been done considering a role for EphB2/EphrinB in adult neural precursor cells. We therefore examined whether the EphB2 receptor tyrosine kinase could directly effect proliferation of SVZ neural precursors and/or direct the cell fate of SVZ cells in vitro. Here, we found that clustered EphB2 increased bromodeoxyuridine (BrdU) incorporation and proliferation of SVZ neurosphere cultures. Immunostaining and RT-PCR analysis for beta-tubulin III (Tuj1) and GFAP indicated 4-day treatment with EphB2 promoted a neuronal phenotype, suggesting that the EphB2 receptor might also direct SVZ cell fate. EphB2 transiently down-regulated SVZ cell mRNA of Notch1 and Zic1, genes that regulate neurogenesis and neuronal differentiation. Notch1 has been implicated in apoptosis of neural precursors, however, a cell viability assay revealed no statistical difference between EphB2-treated and control cultures. When SVZ neurospheres were cultured upon Matrigel, EphB2 attenuated radial migration of SVZ cells in vitro. These results demonstrate that EphB2/EphrinB signaling directly induces SVZ proliferation, decreases migration, and promotes a neuronal fate of SVZ neural precursors independent of cell survival.

Animals↗

PubMed2005

Investigation of neural progenitor cell induced angiogenesis after embolic stroke in rat using MRI.

Using MRI, we investigated dynamic changes of brain angiogenesis after neural progenitor cell transplantation in the living adult rat subjected to embolic stroke. Neural progenitor cells isolated from the subventricular zone (SVZ) of the adult rat were labeled by superparamagnetic particles and intracisternally transplanted into the adult rat 48 h after stroke (n = 8). Before and after the transplantation, an array of MRI parameters were measured, including high resolution 3D MRI and quantitative T1, T1sat (T1 in the presence of an off-resonance irradiation of the macromolecules of brain), T2, the inverse of the apparent forward transfer rate for magnetization transfer (kinv), cerebral blood flow (CBF), cerebral blood volume (CBV), and blood-to-brain transfer constant (Ki) of Gd-DTPA. The von Willerbrand factor (vWF) immunoreactive images of coronal sections obtained at 6 weeks after cell transplantation were used to analyze vWF immunoreactive vessels. MRI measurements revealed that grafted neural progenitor cells selectively migrated towards the ischemic boundary regions. In the ischemic boundary regions, angiogenesis confirmed by an increase in vascular density and the appearance of large thin wall mother vessels was coincident with increases of CBF and CBV (CBF, P < 0.01; CBV, P < 0.01) at 6 weeks after treatment, and coincident with transient increases of K(i) with a peak at 2 to 3 weeks after cell therapy. Relative T1, T1sat, T2, and kinv decreased in the ischemic boundary regions with angiogenesis compared to that in the non-angiogenic ischemic region (T1, P < 0.01 at 6 weeks; T1sat, P < 0.05 at 2 to 6 weeks; T2, P < 0.05 at 3 to 6 weeks; kinvP < 0.05 at 6 weeks). Of these methods, Ki appear to be the most useful MR measurements which identify and predict the location and area of angiogenesis. CBF, CBV, T1sat, T1, T2, and kinv provide complementary information to characterize ischemic tissue with and without angiogenesis. Our data suggest that select MRI parameters can identify the cerebral tissue destined to undergo angiogenesis after treatment of embolic stroke with cell therapy.

Algorithms↗

PubMed2005

Low-dose photodynamic therapy increases endothelial cell proliferation and VEGF expression in nude mice brain.

We tested whether low-dose photodynamic therapy (PDT) induces an angiogenic response in the normal brain of nude mice (n=20). Normal brains of nude mice were subjected to PDT at low doses (Photofrin: 2 mg/kg; optical: 2 J/cm(2) and 4 J/cm(2)). BrdU (50 mg/kg) was injected (intraperitoneally, i.p.) daily from PDT treatment to sacrifice (1 and 2 weeks after PDT). Laser scanning confocal microscopy, immunohistochemistry, and immunofluorescence staining were performed to assay angiogenic response. Morphological results show no significant tissue damage induced by PDT and two- and three-dimensional image analyses revealed no significant difference in vascular structure between the areas of exposure to PDT and contralateral areas in all mice. However, the number of BrdU immunoreactive cells were significantly increased in the areas of PDT treatment compared with contralateral hemisphere in both groups, and the number of BrdU-positive cells increased in a PDT-dose-dependent manner. Furthermore, immunohistochemical data indicate that PDT at these low doses significantly induces the expression of the vascular endothelial growth factor (VEGF) in PDT-treated regions in the 1-week group, but not in the 2-week group. These data indicate that low-dose PDT results in increased VEGF expression and endothelial cell proliferation in normal brains.

Animals↗

PubMed2005

Assessing combination treatments in acute stroke: preclinical experiences.

BACKGROUND: Acute ischemic stroke is a complex disease. Treatment success may require combining different therapeutic approaches. An obvious treatment combination in acute ischemic stroke is a thrombolytic therapy, adjuvant with a neuroprotective agent to have better stroke recovery. SUMMARY OF REVIEW: Complete factorial designs can assess the synergy of combination treatments and distinguish them from supper-additive, additive or sub-additive effects. A factorial design, a two-way analysis of variance and a novel graphic technique can detect and illustrate interactions of two treatments, which were used to evaluate combination treatments to extend the therapeutic window for thrombolytic therapy in an embolic stroke model on rats. We hypothesized synergy or additive effects on stroke recovery when combining thrombolytic therapy with either an antagonist to the integrin CD11b/CD18 (UK-279,276) or a glycoprotein IIb/IIIa receptor inhibitor. CONCLUSIONS: Factorial designs offer an efficient approach to study synergistic effects of two treatments. Our graphical technique provides a powerful, intuitive and quantitative explanation of joint treatment effects. Combining thrombolytic therapy with a neuroprotectant yielded a super-additive or additive treatment effect for two preclinical experiments designed to extend the thrombolytic therapeutic window for stroke.

Analysis of Variance↗

PubMed2005

SDF-1 and CXCR4 are up-regulated by VEGF and contribute to glioma cell invasion.

Glioma cells produce vascular endothelial growth factor (VEGF) to induce vascularization and thereby supply the malignant tissue with oxygen and nutrients. However, little is known about the direct effects of VEGF on tumor cells. In this study, we investigate the ability of VEGF to promote proliferation and invasion of human glioma cells (U251n). Since the chemokine and its receptor, SDF-1/CXCR4, promote glioma cell proliferation and are up-regulated in human glioblastomas, we also tested the effects of VEGF on SDF-1 and CXCR4 mRNA expression. Using cell culture, the effect of VEGF on proliferation of U251n cells was measured using ELISA to detect incorporated BrdU as a marker of DNA syntheses. The effects of VEGF and SDF-1 on U251n cell invasion and proliferation were measured using inhibitors to VEGF receptor1 and receptor2, DC101 and MF1, respectively, and a CXCR4 antagonist (AMD3100). SDF-1 and CXCR4 mRNA expression in U251n and U87MG cells were measured using quantitative PCR. VEGF antisense phosphorothioate oligodeoxynucleotide (AS-VEGF) was also used to down-regulate VEGF expression in U251n cells. VEGF significantly increased U251n cell proliferation and invasion in a dose-dependent manner. These effects were blocked by the VEGF receptor inhibitors, DC101/MF1. The CXCR4 antagonist AMD3100 blocked U251n increased invasion, but not proliferation. CXCR4 and SDF-1 mRNA were up-regulated when U251n and U87MG cells were treated with VEGF. Eight micrometer VEGF antisense phosphorothioate oligodeoxynucleotide (AS-VEGF) down-regulated CXCR4 and SDF-1 mRNA levels in U251n cells. VEGF has a direct effect on U251n glioma cell proliferation and invasion. VEGF up-regulates SDF-1 and CXCR4 mRNA expression, and contributes to U251n cell invasion.

Cell Line, Tumor↗

PubMed2005

Early prediction of gross hemorrhagic transformation by noncontrast agent MRI cluster analysis after embolic stroke in rat.

BACKGROUND AND PURPOSE: Our goal was to develop magnetic resonance indices, without image contrast agent enhancement, that predict hemorrhagic transformation (HT) in a rat model of embolic stroke. METHODS: Male Wistar rats subjected to embolic stroke with (n=12) or without (n=10) the combination treatment with recombinant tissue plasminogen activator and an anti-platelet glycoprotein IIb/IIIa antibody 7E3 F(ab')2 initiated at 4 hours after onset of stroke were investigated using a 7-T MRI system. Radiofrequency saturation T1 (T1sat) maps with magnetization transfer, apparent diffusion coefficient of water (ADCw) maps in 3 directions, and T2 maps were measured at 2, 24, and 48 hours after embolization. MRI data were analyzed individually and using 2D cluster plots. Histological measurements were obtained at 48 hours. RESULTS: Gross hemorrhage was detected at 48 hours in 7 (4 control, 3 treated) of 22 animals. The 2D cluster plot using MRI T1sat and ADCw maps obtained at 2 hours after stroke predicted all gross HT. The location of gross hemorrhage predicted by the 2D cluster plot was within 0.75 mm of the identifying MRI cluster. CONCLUSIONS: The 2D MRI cluster plot analysis using T1sat and ADCw maps acquired at 2 hours after the onset of embolic stroke predicts gross HT.

Animals↗

PubMed2005

Functional recovery in aged and young rats after embolic stroke: treatment with a phosphodiesterase type 5 inhibitor.

BACKGROUND AND PURPOSE: Advanced age is associated with a decrease in brain plasticity compared with the young adult. Sildenafil, a phosphodiesterase type 5 (PDE5) inhibitor promotes brain plasticity and improves functional outcome after stroke in the young animal. Here, we test the hypothesis that sildenafil provides restorative therapeutic benefit to the aged animal. METHODS: Male Wistar rats (aged, 18-month old; young, 3-month old) were subjected to embolic stroke. Saline or sildenafil was administered daily at a dose of 2 mg/kg orally or 10 mg/kg subcutaneously for 7 consecutive days starting 24 hour after stroke onset. RESULTS: Aged rats exhibited significant impairment of functional recovery and reductions of vascular density, and endothelial cell proliferation compared with young rats. Aged rats treated with sildenafil at a dose of 10 mg/kg but not 2 mg/kg, showed significant improvements of functional recovery and concomitant increases in cortical cyclic guanosine 3',5'-cyclic monophosphate (cGMP) level, vascular density, endothelial cell proliferation, and synaptogenesis compared with aged rats treated with saline. In young rats, treatment with sildenafil at a dose of 2 or 10 mg/kg significantly enhanced functional recovery and amplified brain plasticity compared with young rats treated with saline. CONCLUSIONS: Age is associated with reduction of angiogenesis, and poor neurological functional recovery after stroke. However, treatment of aged stroke rats with sildenafil improves functional recovery that is likely fostered by enhancement of angiogenesis and synaptogenesis.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2005

Endothelial nitric oxide synthase regulates brain-derived neurotrophic factor expression and neurogenesis after stroke in mice.

Here, we investigate the effects of endothelial nitric oxide synthase (eNOS) on angiogenesis, neurogenesis, neurotrophic factor expression, and neurological functional outcome after stroke. Wild-type and eNOS knock-out (eNOS-/-) mice were subjected to permanent occlusion of the right middle cerebral artery. eNOS-/- mice exhibited more severe neurological functional deficit after stroke than wild-type mice. Decreased subventricular zone (SVZ) progenitor cell proliferation and migration, measured using bromodeoxyuridine, Ki-67, nestin, and doublecortin immunostaining in the ischemic brain, and decreased angiogenesis, as demonstrated by reduced endothelial cell proliferation, vessel perimeter, and vascular density in the ischemic border, were evident in eNOS-/- mice compared with wild-type mice. eNOS-deficient mice also exhibited a reduced response to vascular endothelial growth factor (VEGF)-induced angiogenesis in a corneal assay. ELISAs showed that eNOS-/- mice have decreased brain-derived neurotrophic factor (BDNF) expression but not VEGF and basic fibroblast growth factor in the ischemic brain compared with wild-type mice. In addition, cultured SVZ neurosphere formation, proliferation, telomerase activity, and neurite outgrowth but not cell viability from eNOS-/- mice were significantly reduced compared with wild-type mice. BDNF treatment of SVZ cells derived from eNOS-/- mice restored the decreased neurosphere formation, proliferation, neurite outgrowth, and telomerase activity in cultured eNOS(-/-) SVZ neurospheres. SVZ explant cell migration also was significantly decreased in eNOS-/- mice compared with wild-type mice. These data indicate that eNOS is not only a downstream mediator for VEGF and angiogenesis but also regulates BDNF expression in the ischemic brain and influences progenitor cell proliferation, neuronal migration, and neurite outgrowth and affects functional recovery after stroke.

Animals↗

PubMed2005

Erythropoietin treatment improves neurological functional recovery in EAE mice.

Erythropoietin (EPO), originally recognized for its central role in erythropoiesis, has been shown to improve neurological outcome after stroke. Here, we investigated the treatment of experimental autoimmune encephalomyelitis (EAE) in mice with EPO. Mice were treated with recombinant human EPO (rhEPO) upon onset of paresis. Neurological functional tests were scored daily by grading of clinical signs (score 0-5). Hematoxylin and eosin (HE) staining of cerebral tissue was performed to detect inflammatory infiltrates. Double staining for Luxol fast blue and Bielshowsky was used to demonstrate myelin and axons, respectively. Immunohistochemistry was performed to measure the expression of bromodeoxyuridine (BrdU, a marker for cell proliferation), NG2 (a marker for oligodendrocyte progenitor cells) and brain-derived neurotrophic factor (BDNF). Treatment with rhEPO significantly improved neurological functional recovery, reduced inflammatory infiltrates and demyelination, and increased oligodendrocyte progenitor cell proliferation and BDNF+ cells compared to the EAE controls. These data indicate that rhEPO treatment improved functional recovery after EAE in mice, possibly, via stimulating oligodendrogenesis, downregulating proinflammatory infiltrates and by elevating BDNF expression.

Animals↗

PubMed2005

Functional recovery after embolic stroke in rodents by activated protein C.

A serine protease activated protein C has been shown to be a powerful neuroprotectant in stressed neurons and in hypoxic brain endothelium. In a clinically relevant model of embolic stroke in rodents, we now show that administration of activated protein C alone or in combination with tissue plasminogen activator, or both, 4 hours after embolic stroke improves the functional outcome and reduces brain infarction within 7 days of stroke. In contrast, tissue plasminogen activator alone was not protective. Thus, activated protein C may be useful as a new stand-alone therapy for clinical stroke and to extend the time window of thrombolytic therapy.

Animals↗

PubMed2005

Gliosis and brain remodeling after treatment of stroke in rats with marrow stromal cells.

The long-term (4-month) responses to treatment of stroke in the older adult rat, using rat bone marrow stromal cells (MSCs), have not been investigated. Retired breeder rats were subjected to middle cerebral artery occlusion (MCAo) alone, or injected intravenously with 3 x 10(6) MSCs, at 7 days after MCAo. Functional recovery was measured using an adhesive-removal patch test and a modified neurological severity score. Bromodeoxyuridine, a cell proliferation marker, was injected daily for 14 before sacrifice. Animals were sacrificed 4 months after stroke. Double immunostaining was used to identify cell proliferation and cell types for axons, astrocytes, microglia, and oligodendrocytes. MSC treatment induced significant improvement in neurological outcome after MCAo compared with control rats. MSC treatment reduced the thickness of the scar wall (P < 0.05) and reduced the numbers of microglia/macrophages within the scar wall (P < 0.01). Double staining showed increased expression of an axonal marker (GAP-43), among reactive astrocytes in the scar boundary zone and in the subventricular zone in the treated rats. Bromodeoxyuridine in cells preferentially colocalized with markers of astrocytes (GFAP) and oligodendrocytes (RIP) in the ipsilateral hemisphere, and gliogenesis was enhanced in the subventricular zone of the rats treated with MSCs. This is the first report to show that MSCs injected at 7 days after stroke improve long-term neurological outcome in older animals. Brain tissue repair is an ongoing process with reactive gliosis, which persists for at least 4 months after stroke. Reactive astrocytes responding to MSC treatment of ischemia may also promote axonal regeneration during long-term recovery.

Animals↗