Biomedical subjects

Michael Chopp

Publications and source records attributed to Michael Chopp.

At least 19 recordsLinked to original sources

PubMed2025

Multicompartment Quantitative Proteomics Revealing Potential Mechanisms Underlying the Treatment Effects of Mesenchymal-Derived Extracellular Vesicles in a Monkey Model of Cortical Injury.

Previous studies have demonstrated that mesenchymal stromal cell-derived extracellular vesicles (MSC-EVs) enhance functional recovery after cortical injury in rhesus monkeys by reducing chronic microglial inflammation, neuronal damage, and myelination deficits. However, the signaling pathways underlying these therapeutic effects remain largely unexplored. In this study, employing a reliable quantitative proteomics platform UHR-IonStar, we identified the protein cargo of MSC-EVs infused intravenously to rhesus monkeys 24 h and 2 weeks post-injury to the motor cortex. We then analyzed global protein expression changes across cerebrospinal fluid (CSF), plasma, and brain tissue of MSC-EV-treated versus vehicle-treated female, aged rhesus monkeys. A total of 1241/431/4124 monkey proteins were reliably quantified in CSF/plasma/tissue samples, respectively. Longitudinal analysis of CSF and plasma samples highlighted a shift from MSC-EV modulation of inflammatory and metabolic proteins in plasma at early recovery (2 weeks), toward modulation of plasticity-related proteins in CSF and brain tissue at later stages (4 weeks). Further protein-protein interaction analysis identified potential MSC-EV targets related to complementary signaling, proteolysis, and aminoglycan stability, which aligned with our previous findings. This comprehensive, multicompartment monkey proteomics study advances understanding of MSC-EV contents and treatment effects, paving the way for novel treatment of cortical injury.

Animals↗

PubMed2007

Stroke induces ependymal cell transformation into radial glia in the subventricular zone of the adult rodent brain.

Adult ependymal cells are postmitotic and highly differentiated. Radial glial cells are neurogenic precursors. Here, we show that stroke acutely stimulated adult ependymal cell proliferation, and dividing ependymal cells of the lateral ventricle had genotype, phenotype, and morphology of radial glial cells in the rat. The majority of radial glial cells exhibited symmetrical division about the cell cleavage plane, and a radial fiber was maintained throughout each stage of cell mitosis. Increases of radial glial cells parallel expansion of neural progenitors in the subventricular zone (SVZ). Furthermore, after stroke radial glial cells derived from the SVZ supported neuron migration. These results indicate that adult ependymal cells divide and transform into radial glial cells after stroke, which could function as neural progenitor cells to generate new neurons and act as scaffolds to support neuroblast migration towards the ischemic boundary region.

Animals↗

PubMed2006

Angiogenesis and improved cerebral blood flow in the ischemic boundary area detected by MRI after administration of sildenafil to rats with embolic stroke.

To dynamically investigate the long-term response of an ischemic lesion in rat brain to the administration of sildenafil, male Wistar rats subjected to embolic stroke were treated with sildenafil (n=11) or saline (n=10) at a dose of 10 mg/kg administered subcutaneously 24-h after stroke and daily for an additional 6 days. Magnetic resonance images were acquired and functional performance was measured in all animals at 1 day, 2 days and weekly for 6 weeks post-stroke. All rats were sacrificed 6 weeks after stroke and endothelial barrier antigen immunostaining was employed for morphological analysis and quantification of cerebral vessels. Map-ISODATA was computed from T(1), T(2) and T(1sat) maps. ISODATA derived tissue signatures characterize the degree of ischemic injury. Based on the map-ISODATA calculated at 6 weeks, the ischemic lesion for each animal was divided into two specific regions, the ischemic boundary and ischemic core. The temporal profiles of cerebral blood flow (CBF) and tissue signature were retrospectively tracked in these two regions and were compared with histological evaluation and functional outcome. After 1 week of sildenafil treatment, the ischemic lesion exhibited two significantly different regions, with higher CBF level and correspondingly, lower tissue signature value in the boundary region than in the core region. Sildenafil treatment did not significantly reduce the lesion size, but did enhance angiogenesis. Functional performance was significantly increased after sildenafil treatment compared with the control group. Administration of sildenafil to rats with embolic stroke enhances angiogenesis and selectively increases the CBF level in the ischemic boundary, and improves neurological functional recovery compared to saline-treated rats.

Animals↗

PubMed2006

Ectopic doublecortin gene expression suppresses the malignant phenotype in glioblastoma cells.

Doublecortin (DCX) is one of the three genes found from Affymetrix gene chip analysis related to glioma patient survival. Two other genes (e.g., osteonectin and semaphorin 3B) are well characterized as antioncogenic and tumor suppressor genes. However, there is no report about the involvement of DCX in cancer. Here, we show that gene transfer technology into DCX-deficient glioblastoma cell lines, such as A172, U87, U251N, RG2, and 9L, with DCX cDNA significantly suppressed growth of these glioma cells. U87 cells with ectopic expression of DCX exhibit a marked suppression of the transformed phenotype as growth arrested in the G(2) phase of the cell cycle progression, small colony formation in soft agar, and no tumor formation in nude rats. This transformed phenotype can be restored by knocking down DCX expression with DCX small interfering RNA. DCX was highly phosphorylated in glioma cells. Phosphorylation in the glioma cells was greater than in noncancer cells such as mouse NIH 3T3 and human embryonic kidney 293T cells. Coimmunoprecipitation of the phosphorylated DCX and spinophilin/neurabin II from DCX-synthesizing glioma cells indicated their interaction. This interaction would lead to a block of anchorage-independent growth as neurabin II is a synergistic inhibitor of anchorage-independent growth with p14ARF (ARF). Interaction between phosphorylated DCX and neurabin II may induce the association of the protein phosphatase 1 catalytic subunit (PP1) with neurabin II and inactivate PP1 and block mitosis during G(2) and M phases of the cell cycle progression. Thus, DCX seems to be a tumor suppressor of glioma.

3T3 Cells↗

PubMed2006

Linkage of cell cycle kinetics between embryonic and adult stroke models: an analytical approach.

In the adult brain, neurogenesis occurs in the subventricular zone (SVZ) of the lateral ventricle. The proliferating population and the cell cycle kinetics in the ventricular zone regulate cortical neurogenesis during the development. Using the embryonic model, we investigated kinetics of SVZ cells in adult rats after stroke, incorporating migration of SVZ cells to the ischemic boundary. Concurrent linear regressions were considered through iteration to improve precision of parameter estimation. We found no model-fit difference in stroke with and without the migration (p=0.31), suggesting no migration effect on assessment of the cell kinetics. Stroke increased SVZ cell proliferation (20% in non-stroke and 31% in stroke p<0.01). Cell cycle durations in stroke were reduced for the total cycle length (19h for non-stroke and 15.3h for stroke, p<0.05), in G1 phase (12.6 h for non-stroke and 9.6 h for stroke, p<0.01), but were the same in S, M2, and in G2 phases compared to non-stroke, indicating that stroke reduces the total cell cycle length, specially in G1 phase. We conclude that cell cycle kinetic models for cortical development can be adapted to the kinetics of adult SVZ cells after stroke. The analytical approach may be useful for studying neural progenitor cell proliferation under different treatments.

Aging↗

PubMed2006

Multiparametric iterative self-organizing data analysis of ischemic lesions using pre- or post-Gd T1 MRI.

BACKGROUND: The purpose of this work was to evaluate effects of Gd-diethylenetriaminepentacetic acid (DTPA) injection on T(1)-weighted images of stroke and lesion segmentation and characterization results generated by our multiparametric iterative self-organizing data (ISODATA) method. The post-Gd image incorporates vasculature information into the analysis. METHODS: Either a pre-Gd T(1)-weighted image (T1WI) or a post-Gd T1WI was used along with diffusion-, T(2)- and proton-density-weighted images in the analysis. ISODATA is a data-driven method that segments and characterizes tissue damage in stroke using multiparametric MRI. RESULTS: Experimental results in both animal and human studies showed that the use of post-Gd T1WI modified the segmentation and characterization results on the periphery of the lesion. The peripheral region that changes with Gd-DTPA has a higher permeability compared to the rest of the lesion. Either of the data sets (including pre- or post-Gd T1WI) was used to estimate the tissue recovery and generated consistent results. CONCLUSIONS: This study shows that our multiparametric ISODATA approach consistently identifies and characterizes the core of the ischemic lesion. It also shows that the inclusion of post-Gd T1WI results in the segmentation and characterization of the lesion periphery if it has a higher permeability compared to the rest of the lesion. Finally, it confirms that the multiparametric ISODATA MRI characterizes tissue damage and recovery in stroke.

Algorithms↗

PubMed2006

Activated protein C inhibits tissue plasminogen activator-induced brain hemorrhage.

Brain hemorrhage is a serious complication of tissue plasminogen activator (tPA) therapy for ischemic stroke. Here we report that activated protein C (APC), a plasma serine protease with systemic anticoagulant, anti-inflammatory and antiapoptotic activities, and direct vasculoprotective and neuroprotective activities, blocks tPA-mediated brain hemorrhage after transient brain ischemia and embolic stroke in rodents. We show that APC inhibits a pro-hemorrhagic tPA-induced, NF-kappaB-dependent matrix metalloproteinase-9 pathway in ischemic brain endothelium in vivo and in vitro by acting through protease-activated receptor 1. The present findings suggest that APC may improve thrombolytic therapy for stroke, in part, by reducing tPA-mediated hemorrhage.

Animals↗

PubMed2006

Wound repair by bone marrow stromal cells through growth factor production.

We have previously shown that treatment with bone marrow stromal cells (BMSCs) augments the healing of fascial wounds in the rat. However, the biochemical mechanism by which BMSCs improve wound healing was not investigated. Growth factors have been shown to play a key role in repairing damaged tissue. In this study, we investigated whether BMSCs are capable of producing growth factors that play a critical role in healing of the damaged tissue. Growth factor expression in BMSCs stimulated with pro-inflammatory cytokines or wound superfusate was measured by RT-PCR and growth factor-specific quantitative sandwich enzyme-linked immunosorbent assay (ELISA). RT-PCR analysis demonstrated that BMSCs are capable of expressing transforming growth factor beta-1 (TGF-beta1), epidermal growth factor (EGF), vascular endothelial growth factor (VEGF) platelet-derived growth factor (PDGF), keratinocyte growth factor (KGF), fibroblast growth factor (FGF), and hepatocyte growth factor (HGF) constitutively or upon stimulation with LPS, IL-1alpha, or TNF-alpha. Quantitative analysis of growth factor production by ELISA showed that BMSCs do not secrete TGF-beta1, EGF or VEGF in response to uninjured fascia tissue superfusate; however, production of these growth factors is significantly increased when cells were stimulated with wound tissue superfusate. The ability of wound to stimulate growth factor production in BMSCs could be detected as early as day 1 and lasted through day 7 after wounding. Thus, growth factor production by BMSCs in response to wound microenvionment suggests that BMSCs might augment wound healing through the responsive secretion of growth factors that enhance angiogenesis and promote wound repair.

Animals↗

PubMed2006

Tadalafil, a long-acting type 5 phosphodiesterase isoenzyme inhibitor, improves neurological functional recovery in a rat model of embolic stroke.

Sildenafil, a type 5 phosphodiesterase isoenzyme (PDE5) inhibitor with a short half-life, increases brain cyclic guanosine monophosphate (cGMP) levels and improves neurological functional recovery when administered after stroke. In the present study, we investigated the effects of tadalafil (Cialis), a long acting PDE5 inhibitor, on brain cGMP levels, neurogenesis, angiogenesis, and neurological function during stroke recovery in a rat model of embolic stroke. Male Wistar rats (n=28) were subjected to embolic middle cerebral artery (MCA) occlusion. Tadalafil was orally administered every 48 h at a dose of 2 mg/kg or 10 mg/kg for 6 consecutive days starting 24 h after stroke onset. Control animals received the equivalent volume of saline at the same time points. For mitotic labeling, bromodeoxyuridine (BrdU, 100 mg/kg) was administered twice a day at 5, 6, and 7 days after stroke. ELISA assays were performed to evaluate the specificity of the effect of tadalafil on cGMP. Treatment with tadalafil at a dose of 2 or 10 mg/kg significantly improved neurological functional recovery compared with saline-treated rats. In addition, tadalafil treatment increased cerebral vascular density and the percentage of BrdU-positive endothelial cells around the ischemic boundary compared with saline-treated rats. Moreover, tadalafil-treated rats showed greater ipsilateral SVZ cell proliferation than saline-treated rats. However, treatment with tadalafil did not reduce infarct volume when compared to the saline group. Tadalafil selectively increased cGMP but not cyclic adenosine monophosphate (cAMP) in brain. Our data demonstrate that treatment of ischemic stroke with tadalafil improved functional recovery, which was associated with increases of brain cGMP levels and enhancement of angiogenesis and neurogenesis.

3',5'-Cyclic-GMP Phosphodiesterases↗

PubMed2006

Detection of BBB disruption and hemorrhage by Gd-DTPA enhanced MRI after embolic stroke in rat.

Thrombolytic therapy with rtPA increases the risk of hemorrhagic transformation (HT) after cerebral ischemia. We employed contrast enhancement MRI with Gd-DTPA to detect HT in a rat model of embolic stroke treated with rtPA and a glycoprotein IIb/IIIa receptor antagonist, 7E3 F(ab')2, at 4 h after embolic stroke. Male Wistar rats were subjected to embolic stroke and treated with the combination of rtPA and 7E3 F(ab')2 (n=12) or with saline (n=10) at 4 h after onset of stroke. MRI studies were performed immediately and at 24 h after embolization using a 7-T system. Histological measurements were obtained at 48 h. With Gd-DTPA, T1WI images and permeability related MRI parameters (the blood-to-brain transfer constant, Ki, and the distribution volume of mobile protons, Vp) of 15 out of 18 animals showed hyperintensity regions in gross or microscopic HT areas at 24 h, confirmed histologically at 48 h post stroke. Contrast enhancement MRI detected six of seven (86%) animals with gross HT and nine of eleven (82%) animals with microscopic HT at 24 h after ischemia. Two of eighteen animals with HT, had MRI indices of hemorrhage at 3 h post stroke. However, compared to HT data measured histologically at 48 h in embolic stroke rats, the enhanced areas by Gd-DTPA at 24 h were larger, and the patterns (time, intensity and region) did not directly correlate to the subtypes of HT, i.e., gross or microscopic hemorrhage. Contrast enhancement MRI using Gd-DTPA provides a method to detect gross and microscopic HT after stroke in rats.

Animals↗

PubMed2006

Low-level laser therapy applied transcranially to rats after induction of stroke significantly reduces long-term neurological deficits.

BACKGROUND AND PURPOSE: Low-level laser therapy (LLLT) modulates various biological processes. In the present study, we assessed the hypothesis that LLLT after induction of stroke may have a beneficial effect on ischemic brain tissue. METHODS: Two sets of experiments were performed. Stroke was induced in rats by (1) permanent occlusion of the middle cerebral artery through a craniotomy or (2) insertion of a filament. After induction of stroke, a battery of neurological and functional tests (neurological score, adhesive removal) was performed. Four and 24 hours poststroke, a Ga-As diode laser was used transcranially to illuminate the hemisphere contralateral to the stroke at a power density of 7.5 mW/cm2. RESULTS: In both models of stroke, LLLT significantly reduced neurological deficits when applied 24 hours poststroke. Application of the laser at 4 hours poststroke did not affect the neurological outcome of the stroke-induced rats as compared with controls. There was no statistically significant difference in the stroke lesion area between control and laser-irradiated rats. The number of newly formed neuronal cells, assessed by double immunoreactivity to bromodeoxyuridine and tubulin isotype III as well as migrating cells (doublecortin immunoactivity), was significantly elevated in the subventricular zone of the hemisphere ipsilateral to the induction of stroke when treated by LLLT. CONCLUSIONS: Our data suggest that a noninvasive intervention of LLLT issued 24 hours after acute stroke may provide a significant functional benefit with an underlying mechanism possibly being induction of neurogenesis.

Animals↗

PubMed2006

Stroke-induced subventricular zone proliferation is promoted by tumor necrosis factor-alpha-converting enzyme protease activity.

Cerebral stroke induces proliferation of subventricular zone (SVZ) neural progenitor cells in adult rodent brain. Tumor necrosis factor-alpha-converting enzyme (TACE) proteolysis sheds the nonamyloidogenic soluble ectodomain of the amyloid precursor protein (APP) and is a convertase for tumor necrosis factor-alpha (TNFalpha). The resulting soluble peptides of APP and TNFalpha are mitogenic for neural progenitor cells of the SVZ. Therefore, we hypothesized a role for TACE proteolysis in stroke-induced neurogenesis. Using laser-capture microdissection, we found TACE transcription was increased in SVZ cells of ischemic brain. Immunohistochemistry revealed TACE protein was upregulated in SVZ neuroblasts. Intraventricular infusion of tumor necrosis factor-alpha protease inhibitor-2 (TAPI-2) decreased bromodeoxyuridine incorporation in SVZ cells of rats subjected to middle cerebral artery occlusion. Furthermore, primary culture SVZ neurospheres from ischemic brain overexpress TACE and its substrates APP and TNF-alpha. These cells proliferated more rapidly, possessed increased TACE protease-dependent alpha-secretase activity, and released more soluble APP and TNFalpha compared with nonischemic control. In addition, TAPI-2 reduced SVZ neuroblast migration out of SVZ explants in vitro. These findings indicate TACE proteolysis as a promoter of stroke-induced SVZ progenitor cell neurogenesis, and suggest this protease activity may represent an attractive therapeutic target for stroke recovery.

ADAM Proteins↗

PubMed2006

Bone marrow stromal cells reduce axonal loss in experimental autoimmune encephalomyelitis mice.

We investigated the ability of human bone marrow stromal cell (hBMSC) treatment to reduce axonal loss in experimental autoimmune encephalomyelitis (EAE) mice. EAE was induced in SJL/J mice by injection with proteolipid protein (PLP). Mice were injected intravenously with hBMSCs or PBS on the day of clinical onset, and neurological function was measured daily (score 0-5) until 45 weeks after onset. Mice were sacrificed at week 1, 10, 20, 34, and 45 after clinical onset. Bielshowsky silver was used to identify axons. Immunohistochemistry was performed to measure the expression of nerve growth factor (NGF) and MAB1281, a marker of hBMSCs. hBMSC treatment significantly reduced the mortality, the disease severity, and the number of relapses in EAE mice compared with PBS treatment. Axonal density and NGF(+) cells in the EAE brain were significantly increased in the hBMSC group compared with the PBS group at 1, 10, 20, 34, and 45 weeks. Disease severity was significantly correlated with decreased axonal density and decreased NGF, and increased axonal density was significantly correlated with reduced loss of NGF expression after hBMSC treatment. Most of the NGF(+) cells are brain parenchymal cells. Under 5% of MAB1281(+) cells colocalized with NG2(+), a marker of oligodendrocyte progenitor cells. Nearly 10% of MAB1281(+) cells colocalized with GFAP, a marker of astrocytes, and MAP-2, a marker of neurons. Our findings indicate that hBMSCs improve functional recovery and may provide a potential therapy aimed at axonal protection in EAE mice, in which NGF may play a vital role.

Animals↗

PubMed2006

MRI detects white matter reorganization after neural progenitor cell treatment of stroke.

We evaluated the effects of neural progenitor cell treatment of stroke on white matter reorganization using MRI. Male Wistar rats (n = 26) were subjected to 3 h of middle cerebral artery occlusion and were treated with neural progenitor cells (n = 17) or without treatment (n = 9) and were sacrificed at 5-7 weeks thereafter. MRI measurements revealed that grafted neural progenitor cells selectively migrated towards the ischemic boundary regions. White matter reorganization, confirmed histologically, was coincident with increases of fractional anisotropy (FA, P < 0.01) after stroke in the ischemic recovery regions compared to that in the ischemic core region in both treated and control groups. Immunoreactive staining showed axonal projections emanating from neurons and extruding from the corpus callosum into the ipsilateral striatum bounding the lesion areas after stroke. Fiber tracking (FT) maps derived from diffusion tensor imaging revealed similar orientation patterns to the immunohistological results. Complementary measurements in stroke patients indicated that FT maps exhibit an overall orientation parallel to the lesion boundary. Our data demonstrate that FA and FT identify and characterize cerebral tissue undergoing white matter reorganization after stroke and treatment with neural progenitor cells.

Algorithms↗

PubMed2006

Stroke induces gene profile changes associated with neurogenesis and angiogenesis in adult subventricular zone progenitor cells.

Neural progenitor cells in the subventricular zone (SVZ) of the lateral ventricular wall give rise to new neurons throughout rodent life. Ischemic stroke induces angiogenesis and neurogenesis. Using laser capture microdissection (LCM) in combination with microarrays containing approximately 400 known genes associated with stem cells and angiogenesis, we investigated gene profiles of SVZ cells in the adult mouse subjected to middle cerebral artery occlusion. Our data revealed that nonstroke SVZ cells expressed sets of genes that are important for neural progenitor cell proliferation, differentiation, and migration. In addition, stroke SVZ cells expressed many genes involved in neurogenesis during embryonic development but were not detected in nonstroke SVZ cells. Stroke upregulated genes were verified by real-time reverse transcriptase-polymerase chain reaction and immunostaining. These data indicate that adult SVZ cells recapture embryonic molecular signals after stroke and provide insight into the molecular mechanisms, which regulate the biological function of neural progenitor cells in the SVZ of adult rodent brain under physiological and stroke conditions.

Animals↗

PubMed2006

Nitric oxide regulates Angiopoietin1/Tie2 expression after stroke.

We tested whether the nitric oxide donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) aminio] diazen-1-ium-1,2-diolate (DETA-NONOate), increases expression of Angiopoietin (Ang1)/Tie2, which may play a role in regulating angiogenesis and vascular integrity after stroke in rats. Wistar rats were subjected to middle cerebral artery occlusion and treated with or without DETA-NONOate. Stroke rats treated with DETA-NONOate show significantly increased Ang1, Tie2 and Occludin expression in the ischemic border compared with control stroke animals (p < 0.05). Consistent with in vivo data, DETA-NONOate promotes capillary tube formation in cultured brain endothelial cells. Neutralizing Ang1 antibody attenuates DETA-NONOate-induced capillary tube formation. The data suggest that the Ang1/Tie2 axis promotes DETA-NONOate-induced angiogenesis and stabilizes of angiogenic vessels after stroke.

Angiopoietin-1↗

PubMed2006

Dopachrome tautomerase (Dct) regulates neural progenitor cell proliferation.

DOPAchrome tautomerase (Dct) functions downstream of tyrosinase in the biosynthetic pathway of eumelanin by catalyzing the conversion of dopachrome to 5,5-dihydroxyindole-2-carboxylic acid (DHICA) in pigment cells. Dct transcription is regulated directly or synergistically by Pax3, Sox10 and microphthalmia transcription factor (MITF). Using Dct-lacZ transgenic mice, we measured the spatial and temporal pattern of Dct expression in vivo during neocortical neurogenesis in the brain. Dct was expressed in all layers of the dorsal telencephalon in E10.5. At E15.5 and E17.5 when cortical neurogenesis occurs, expression of Dct was primarily localized to the ventricular zone (VZ) where neuronal stem cells reside. Blocking endogenous Dct by RNAi decreased proliferation of embryonic cortical neural progenitor cells (by 48%, P < 0.05), as determined by BrdU incorporation. In adult brain, Dct/Dct expression decreased in the subventricular zone (SVZ), dentate gyrus and olfactory bulb (OB). However, strong expression of Dct was observed in rostral migratory stream (RMS) and septum. Overexpression of Dct in SVZ cells derived from the adult mice significantly increased the number of cells by 260%, whereas silencing Dct by RNAi decreased cell numbers by 25.8% at 48 h post-nucleofection (P < 0.05). The results of RT-PCR analysis revealed that Dct in the brain lacks exon 7 and is identical to the form of Dct found in neural-crest-derived melanocytes. Our data indicate that Dct, previously known as a melanoblast marker, regulates neural progenitor cell proliferation.

Animals↗

PubMed2006

Matrix metalloproteinase 2 (MMP2) and MMP9 secreted by erythropoietin-activated endothelial cells promote neural progenitor cell migration.

We investigated the hypothesis that endothelial cells activated by erythropoietin (EPO) promote the migration of neuroblasts. This hypothesis is based on observations in vivo that treatment of focal cerebral ischemia with EPO enhances the migration of neuroblasts to the ischemic boundary, a site containing activated endothelial cells and angiogenic microvasculature. To model the microenvironment within the ischemic boundary zone, we used a coculture system of mouse brain endothelial cells (MBECs) and neural progenitor cells derived from the subventricular zone of the adult mouse. Treatment of MBECs with recombinant human EPO (rhEPO) significantly increased secretion of matrix metalloproteinase 2 (MMP2) and MMP9. rhEPO-treated MBEC supernatant as conditioned medium significantly increased the migration of neural progenitor cells. Application of an MMP inhibitor abolished the supernatant-enhanced migration. Incubation of neurospheres alone with rhEPO failed to increase progenitor cell migration. rhEPO activated phosphatidylinositol 3-kinase/Akt (PI3K/Akt) and extracellular signal-regulated kinase (ERK1/2) in MBECs. Selective inhibition of the PI3K/Akt and ERK1/2 pathways significantly attenuated the rhEPO-induced MMP2 and MMP9, which suppressed neural progenitor cell migration promoted by the rhEPO-activated MBECs. Collectively, our data show that rhEPO-activated endothelial cells enhance neural progenitor cell migration by secreting MMP2 and MMP9 via the PI3K/Akt and ERK1/2 signaling pathways. These data demonstrate that activated endothelial cells can promote neural progenitor cell migration, and provide insight into the molecular mechanisms underlying the attraction of newly generated neurons to injured areas in brain.

Animals↗