Makoto Migita

Migration of enhanced green fluorescent protein expressing bone marrow-derived microglia/macrophage into the mouse brain following permanent focal ischemia

Brain ischemia induces a marked response of resident microglia and hematopoietic cells including monocytes/macrophages. The present study was designed to assess the distribution of microglia/macrophages in cerebral ischemia using bone marrow chimera mice known to express enhanced green fluorescent protein (EGFP). At 24 h after middle cerebral artery occlusion (MCAO), many round-shaped EGFP-positive cells migrated to the ischemic core and peri-infarct area. At 48-72 h after MCAO, irregular round- or oval-shaped EGFP/ionized calcium-binding adapter molecule 1 (Iba 1)-positive cells increased in the transition zone, while many amoeboid-shaped or large-cell-body EGFP/Iba 1-positive cells were increased in number in the innermost area of ischemia. At 7 days after MCAO, many process-bearing ramified shaped EGFP/Iba 1-positive cells were detected in the transition to the peri-infarct area, while phagocytic cells were distributed in the transition to the core area of the infarction. The distribution of these morphologically variable EGFP/Iba 1-positive cells was similar up to 14 days from MCAO. The present study directly showed the migration and distribution of bone marrow-derived monocytes/macrophages and the relationship between resident microglia and infiltrated hematogenous element in ischemic mouse brain. It is important to study the distribution of intrinsic and extrinsic microglia/macrophage in ischemic brain, since such findings may allow the design of appropriate gene-delivery system using exogenous microglia/macrophages to the ischemic brain area.

An AAV-derived Apaf-1 dominant negative inhibitor prevents MPTP toxicity as antiapoptotic gene therapy for Parkinson's disease

Adeno-associated virus (AAV) vector delivery of an Apaf-1-dominant negative inhibitor was tested for its antiapoptotic effect on degenerating nigrostriatal neurons in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinsons disease. The wild-type caspase recruitment domain of Apaf-1 was used as a dominant negative inhibitor of Apaf-1 (rAAV-Apaf-1-DN-EGFP). An AAV virus vector was used to deliver it into the striatum of C57 black mice, and the animals were treated with MPTP. The number of tyrosine hydroxylase-positive neurons in the substantia nigra was not changed on the rAAV-Apaf-1-DN-EGFP injected side compared with the noninjected side. We also examined the effect of a caspase 1 C285G mutant as a dominant negative inhibitor of caspase 1 (rAAV-caspase-1-DN-EGFP) in the same model. However, there was no difference in the number of tyrosine hydroxylase-positive neurons between the rAAV-caspase-1-DN-EGFP injected side and the noninjected side. These results indicate that delivery of Apaf-1-DN by using an AAV vector system can prevent nigrostriatal degeneration in MPTP mice, suggesting that it could be a promising therapeutic strategy for patients with Parkinsons disease. The major mechanism of dopaminergic neuronal death triggered by MPTP seems to be the mitochondrial apoptotic pathway.

Differentiation of transplanted bone marrow cells in the adult mouse brain.

BACKGROUND Bone marrow transplantation is reportedly effective in preventing the progression of neurological deterioration in lysosomal storage disorders, although the mechanism underlying the therapeutic effects remains to be elucidated. Recent research on stem cell biology suggests that bone marrow cells contain nonhematopoietic stem cells, including brain precursor cells. To evaluate the contribution of bone marrow cells as carriers for cell and gene therapy of neurological disorders, we studied the fate of transplanted bone marrow cells in the adult mouse brain. METHODS Bone marrow cells were genetically marked with a retroviral vector containing the green fluorescence protein gene and then transplanted into irradiated mice by either systemic infusion or direct injection. To identify cell types, brain sections were stained with specific antibodies against neuronal cell markers-neuron specific enolase for neurons, glial fibrillary acidic protein (GFAP) for astrocytes, carbonic anhydrase II (CAII) for oligodendrocytes, and ionized calcium binding adaptor molecule 1 (Iba1) for microglia-and then examined under a confocal microscope. RESULTS Twenty-four weeks after systemic infusion, transplanted cells expressed Iba1 but none of the other brain cell markers. Conversely, 12 weeks after direct injection, transplanted cells were stained with antibodies against GFAP, CAII, and Iba1. CONCLUSIONS Bone marrow contains cells capable of differentiating into oligodendrocytes, astrocytes, and microglia when exposed to the brain microenvironment. Autologous bone marrow cells may be useful as carriers for ex vivo gene therapy for lysosomal disorders with neurological symptoms.

Hydroxysteroid (17-β) Dehydrogenase 1 Is Dysregulated by Mir-210 and Mir-518c That Are Aberrantly Expressed in Preeclamptic Placentas: A Novel Marker for Predicting Preeclampsia

In this study, to search for novel preeclampsia (PE) biomarkers, we focused on microRNA expression and function in the human placenta complicated with PE. By comprehensive analyses of microRNA expression, we identified 22 microRNAs significantly upregulated in preeclamptic placentas, 5 of which were predicted in silico to commonly target the mRNA encoding hydroxysteroid (17-&bgr;) dehydrogenase 1 (HSD17B1), a steroidogenetic enzyme expressed predominantly in the placenta. In vivo HSD17B1 expression, at both the mRNA and protein levels, was significantly decreased in preeclamptic placentas. Of these microRNAs, miR-210 and miR-518c were experimentally validated to target HSD17B1 by luciferase assay, real-time PCR, and ELISA. Furthermore, we found that plasma HSD17B1 protein levels in preeclamptic pregnant women reflected the decrease of its placental expression. Moreover, a prospective cohort study of plasma HSD17B1 revealed a significant reduction of plasma HSD17B1 levels in pregnant women at 20 to 23 and 27 to 30 weeks of gestation before PE onset compared with those with normal pregnancies. The sensitivities/specificities for predicting PE at 20 to 23 and 27 to 30 weeks of gestation were 0.75/0.67 (cutoff value=21.9 ng/mL) and 0.88/0.51 (cutoff value=30.5 ng/mL), and the odds ratios were 6.09 (95% CI: 2.35–15.77) and 7.83 (95% CI: 1.70–36.14), respectively. We conclude that HSD17B1 is dysregulated by miR-210 and miR-518c that are aberrantly expressed in preeclamptic placenta and that reducing plasma level of HSD17B1 precedes the onset of PE and is a potential prognostic factor for PE.

Long-term systemic therapy of Fabry disease in a knockout mouse by adeno-associated virus-mediated muscle-directed gene transfer

Fabry disease is a systemic disease caused by genetic deficiency of a lysosomal enzyme, α-galactosidase A (α-gal A), and is thought to be an important target for enzyme replacement therapy. We studied the feasibility of gene-mediated enzyme replacement for Fabry disease. The adeno-associated virus (AAV) vector containing the α-gal A gene was injected into the right quadriceps muscles of Fabry knockout mice. A time course study showed that α-gal A activity in plasma was increased to ≈25% of normal mice and that this elevated activity persisted for up to at least 30 weeks without development of anti-α-gal A antibodies. The α-gal A activity in various organs of treated Fabry mice remained 5–20% of those observed in normal mice. Accumulated globotriaosylceramide in these organs was completely cleared by 25 weeks after vector injection. Reduction of globotriaosylceramide levels was also confirmed by immunohistochemical and electronmicroscopic analyses. Echocardiographic examination of treated mice demonstrated structural improvement of cardiac hypertrophy 25 weeks after the treatment. AAV vector-mediated muscle-directed gene transfer provides an efficient and practical therapeutic approach for Fabry disease.

Generation of a Chimeric Mouse Reconstituted with Green Fluorescent Protein-Positive Bone Marrow Cells: A Useful Model for Studying the Behavior of Bone Marrow Cells in Regeneration In Vivo

Studies have indicated that bone marrow contains both hematopoietic stem cells and mesenchymal stem cells that can differentiate into a variety of mesenchymal tissues, such as bone, cartilage, muscle, and adipose tissue. Therefore, bone marrow cells are thought to be very useful for cell and gene therapy for various diseases. However, the multipotentiality of these cells remains unclear. To address this issue, we established a chimeric model mouse stably reconstituted with green fluorescent protein (GFP)-marked bone marrow cells. We injected bone marrow cells from GFP-transgenic C57BL/6 mice into the tail veins of recipient wild-type C57BL/6 mice that had been irradiated with a lethal dose of 10 Gy from a cesium source. Microscopic examination and fluorescence-assisted cell sorter (FACS) analysis showed that bone marrow cells, including mesenchymal cells, were almost completely reconstituted with GFP+ cells 5 weeks after transplantation. FACS analysis with lineage-specific antibodies confirmed that the GFP+ cells could differentiate into all types of blood cells. To confirm the usefulness of this mouse model, we studied the role of circulating bone marrow—derived cells in healing of damaged intestine. We performed amputation and anastomosis of the jejunum 10 cm from the pyloric region of the stomach. On the third day after operation, a large number of GFP+ cells were infiltrated in the area of anastomosis, and these cells were positive for CD45 and F4/80 antigens. In 7 days, several cells became negative for CD45 and F4/80 and positive for a smooth muscle actin antigen, which is specific for smooth muscle. This finding suggested that bone marrow-derived cells had differentiated into smooth muscle. Because reconstituted bone marrow cells, as opposed to injected bone marrow cells, behave naturally, this model is ideal for studying the multipotentiality of bone marrow cells in vivo.

Cardiomyocyte regeneration from circulating bone marrow cells in mice.

We investigated the role of circulating bone marrow cells (BMC) in cardiomyocyte regeneration. BMC, isolated from transgenic mice expressing enhanced green fluorescent protein (GFP), were transplanted into lethally irradiated C57BL6 mice. Five weeks after bone marrow transplantation (BMT), flow cytometric analysis for GFP-positive cells confirmed reconstitution of transplanted bone marrow. Bone marrow transplant mice subsequently underwent left coronary artery ligation (myocardial infarction) or sham-operation, and were killed at 1 mo or 3 mo after operation. Infarct size was similar in bone marrow transplant mice at 1 mo (47.1 ± 5.9%) and at 3 mo (45.3 ± 7.8%), and echocardiography at 2 and 8 wk revealed decreasing left ventricular function. In infarcted heart, GFP-positive cells that expressed desmin and troponin T-C were identified by confocal microscopy. GFP and troponin T-C double-positive cells were predominantly in the peri-infarcted region (1 mo, 365 ± 45 cells/50 sections; 3 mo: 458 ± 100 cells/50 sections; p < 0.05 versus noninfarct, infarct, and sham-operated regions). Furthermore, BMC mobilization and differentiation into cardiomyocytes was found to be complete within 1 mo after myocardial infarction. These results demonstrate that circulating BMC undergo mobilization and differentiation in cardiac cells after myocardial infarction. Future studies are required to determine the molecular signaling mechanisms responsible for this phenomenon.

Ex vivo cell-mediated gene therapy for metachromatic leukodystrophy using neurospheres

Metachromatic leukodystrophy (MLD) is an autosomal recessive disease caused by mutations in the gene encoding the lysosomal enzyme arylsulfatase A (ASA). In MLD, accumulation of the substrate, sulfated glycoprotein, in the central and peripheral nervous systems results in progressive motor and mental deterioration. Neural progenitor cells are thought to be useful for cell replacement therapy and for cell-mediated gene therapy in neurodegenerative diseases. In the present study, we examined the feasibility of ex vivo gene therapy for MLD using neural progenitor cells. Neural progenitor cells (neurospheres) were prepared from the striatum of E14 embryo MLD knockout mice or GFP transgenic mice and were transduced with the VSV pseudotyped HIV vector carrying the ASA gene (HIV-ASA). For in vivo study, neurospheres from GFP mice were transduced with HIV-ASA and inoculated into the brain parenchyma of adult MLD mice. HIV vector-transduced progenitor cells retained the potential for differentiation into neurons, astrocytes and oligodendrocytes in vitro. Expression of ASA in neurospheres transduced with HIV-ASA was confirmed by spectrophotometric enzyme assay and Western blotting. In vivo, GFP-positive cells were detectable 1 month after injection. These cells included GFAP- and MAP2-positive cells. Immunohistochemistry using anti-ASA antibody demonstrated localization of ASA in both GFP-positive and -negative cells. Partial clearance of accumulated sulfatide was confirmed in vivo in MLD knockout mice. The present findings suggest that ASA enzyme is released from migrated neurospheres and is able to digest sulfatide in surrounding cells. Our results suggest the potential of genetically engineered neural progenitor cells (neurospheres) for ex vivo therapy in MLD.

Role of Bone Marrow Cells in the Healing Process of Mouse Experimental Glomerulonephritis

Recent studies have shown bone marrow (BM) cells to differentiate into a variety of cell types and to thereby participate in the reconstitution of damaged organs. In the present study, we examined the extent to which BM-derived cells are incorporated into glomeruli during recovery from experimentally induced nephritis. To investigate the localization of BM cells in glomeruli, chimeric mice were prepared by transplanting BM cells from green fluorescent protein (GFP) transgenic mice into wild-type mice. Five weeks later, glomerulonephritis was induced by intravenous injection of Habu snake venom. Groups of mice were then killed every few days for 42 d, and harvested kidney samples were subjected to immunohistochemical and immunoelectron microscopic analyses with the aim of detecting the presence of GFP(+) cells within glomeruli. Chimeric animals injected with Habu venom developed proliferative glomerulonephritis within 1–3 d. The lesion gradually subsided and the glomerular structure returned to normal within 42 d. Consistent with the disease course, large numbers of GFP(+) cells were present within glomeruli on d 1–3, but most had disappeared by d 7. Nevertheless, some GFP(+) cells did remain within glomeruli showing mesangial proliferative changes, and were found to express thrombomodulin (TM), a specific endothelial cell marker. These GFP-TM–double-positive cells accounted for a mean of 1.31–2.24% of the total glomerular nuclei from d 7 through d 42, levels that remained stable for at least 12 mo. It thus appears that BM cells can give rise to endothelial cells that participate in the remodeling of glomeruli.

Successful Gene Therapy In Utero For Lethal Murine Hypophosphatasia

Hypophosphatasia (HPP), caused by mutations in the gene ALPL encoding tissue-nonspecific alkaline phosphatase (TNALP), is an inherited systemic skeletal disease characterized by mineralization defects of bones and teeth. The clinical severity of HPP varies widely, from a lethal perinatal form to mild odontohypophosphatasia showing only dental manifestations. HPP model mice (Akp2(-/-)) phenotypically mimic the severe infantile form of human HPP; they appear normal at birth but die by 2 weeks of age because of growth failure, hypomineralization, and epileptic seizures. In the present study, we investigated the feasibility of fetal gene therapy using the lethal HPP model mice. On day 15 of gestation, the fetuses of HPP model mice underwent transuterine intraperitoneal injection of adeno-associated virus serotype 9 (AAV9) expressing bone-targeted TNALP. Treated and delivered mice showed normal weight gain and seizure-free survival for at least 8 weeks. Vector sequence was detected in systemic organs including bone at 14 days of age. ALP activities in plasma and bone were consistently high. Enhanced mineralization was demonstrated on X-ray images of the chest and forepaw. Our data clearly demonstrate that systemic injection of AAV9 in utero is an effective strategy for the treatment of lethal HPP mice. Fetal gene therapy may be an important choice after prenatal diagnosis of life-threatening HPP.