RESUMO
Slc17a5-/- mice represent an animal model for the infantile form of sialic acid storage disease (SASD). We analyzed genetic and histological time-course expression of myelin and oligodendrocyte (OL) lineage markers in different parts of the CNS, and related this to postnatal neurobehavioral development in these mice. Sialin-deficient mice display a distinct spatiotemporal pattern of sialic acid storage, CNS hypomyelination and leukoencephalopathy. Whereas few genes are differentially expressed in the perinatal stage (p0), microarray analysis revealed increased differential gene expression in later postnatal stages (p10-p18). This included progressive upregulation of neuroinflammatory genes, as well as continuous down-regulation of genes that encode myelin constituents and typical OL lineage markers. Age-related histopathological analysis indicates that initial myelination occurs normally in hindbrain regions, but progression to more frontal areas is affected in Slc17a5-/- mice. This course of progressive leukoencephalopathy and CNS hypomyelination delays neurobehavioral development in sialin-deficient mice. Slc17a5-/- mice successfully achieve early neurobehavioral milestones, but exhibit progressive delay of later-stage sensory and motor milestones. The present findings may contribute to further understanding of the processes of CNS myelination as well as help to develop therapeutic strategies for SASD and other myelination disorders.
Assuntos
Encéfalo/patologia , Regulação da Expressão Gênica no Desenvolvimento/genética , Leucoencefalopatias , Transtornos Mentais/etiologia , Transportadores de Ânions Orgânicos/deficiência , Doença do Armazenamento de Ácido Siálico , Simportadores/deficiência , Fatores Etários , Animais , Animais Recém-Nascidos , Encéfalo/metabolismo , Deficiências do Desenvolvimento/etiologia , Deficiências do Desenvolvimento/genética , Modelos Animais de Doenças , Proteína Glial Fibrilar Ácida/metabolismo , Filamentos Intermediários/metabolismo , Leucoencefalopatias/complicações , Leucoencefalopatias/etiologia , Leucoencefalopatias/genética , Proteína 1 de Membrana Associada ao Lisossomo/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transportadores de Ânions Orgânicos/genética , Doença do Armazenamento de Ácido Siálico/complicações , Doença do Armazenamento de Ácido Siálico/genética , Doença do Armazenamento de Ácido Siálico/patologia , Simportadores/genéticaRESUMO
Circulating stem cells home within the myocardium, probably as the first step of a tissue regeneration process. This step requires adhesion to cardiac microvascular endothelium (CMVE). In this study, we studied mechanisms of adhesion between CMVE and mesenchymal stem cells (MSCs). Adhesion was studied in vitro and in vivo. Isolated 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate-labeled rat MSCs were allowed to adhere to cultured CMVE in static and dynamic conditions. Either CMVE or MSCs were pretreated with cytokines [IL-1beta, IL-3, IL-6, stem cell factor, stromal cell-derived factor-1, or TNF-alpha, 10 ng/ml]. Control or TNF-alpha-treated MSCs were injected intracavitarily in rat hearts in vivo. In baseline in vitro conditions, the number of MSCs that adhered to CMVE was highly dependent on the flow rate of the superfusing medium but remained significant at venous and capillary shear stress amplitudes. Activation of both CMVE and MSCs with TNF-alpha or IL-1beta before adhesion concentration dependently increased adhesion of MSCs at each studied level of shear stress. Consistently, in vivo, activation of MSCs with TNF-alpha before injection significantly enhanced cardiac homing of MSCs. TNF-alpha-induced adhesion could be completely blocked by pretreating either CMVE or MSCs with anti-VCAM-1 monoclonal antibodies but not by anti-ICAM-1 antibodies. Adhesion of circulating MSCs in the heart appears to be an endothelium-dependent process and is sensitive to modulation by activators of both MSCs and endothelium. Inflammation and the expression of VCAM-1 but not ICAM-1 on both cell types have a regulatory effect on MSC homing in the heart.
