Delayed post-ischaemic neuroprotection following systemic neural stem cell transplantation involves multiple mechanisms

Recent evidence suggests that neural stem/precursor cells (NPCs) promote recovery in animal models with delayed neuronal death via a number of indirect bystander effects. A comprehensive knowledge of how transplanted NPCs exert their therapeutic effects is still lacking. Here, we investigated the effects of a delayed transplantation of adult syngenic NPCs—injected intravenously 72 h after transient middle cerebral artery occlusion—on neurological recovery, histopathology and gene expression. NPC-transplanted mice showed a significantly improved recovery from 18 days post-transplantation (dpt) onwards, which persisted throughout the study. A small percentage of injected NPCs accumulated in the brain, integrating mainly in the infarct boundary zone, where most of the NPCs remained undifferentiated up to 30 dpt. Histopathological analysis revealed a hitherto unreported very delayed neuroprotective effect of NPCs, becoming evident at 10 and 30 dpt. Tissue survival was associated with downregulation of markers of inflammation, glial scar formation and neuronal apoptotic death at both mRNA and protein levels. Our data highlight the relevance of very delayed degenerative processes in the stroke brain that are intimately associated with inflammatory and glial responses. These processes may efficaciously be antagonized by (stem) cell-based strategies at time-points far beyond established therapeutic windows for pharmacological neuroprotectio

Persistent Inflammation Alters the Function of the Endogenous Brain Stem Cell Compartment

Endogenous neural stem/precursor cells (NPCs) are considered a functional reservoir for promoting tissue homeostasis and repair after injury, therefore regenerative strategies that mobilize these cells have recently been proposed. Despite evidence of increased neurogenesis upon acute inflammatory insults (e.g. ischaemic stroke), the plasticity of the endogenous brain stem cell compartment in chronic CNS inflammatory disorders remains poorly characterized. Here we show that persistent brain inflammation, induced by immune cells targeting myelin, extensively alters the proliferative and migratory properties of subventricular zone (SVZ)-resident NPCs in vivo leading to significant accumulation of non-migratory neuroblasts within the SVZ germinal niche. In parallel, we demonstrate a quantitative reduction of the putative brain stem cells proliferation in the SVZ during persistent brain inflammation, which is completely reversed after in vitro culture of the isolated NPCs. Together, these data indicate that the inflamed brain microenvironment sustains a non cell-autonomous dysfunction of the endogenous CNS stem cell compartment and challenge the potential efficacy of proposed therapies aimed at mobilizing endogenous precursors in chronic inflammatory brain disorders

Immune Regulatory Neural Stem/Precursor Cells Protect from Central Nervous System Autoimmunity by Restraining Dendritic Cell Function

The systemic injection of neural stem/precursor cells (NPCs) provides remarkable amelioration of the clinico-pathological features of experimental autoimmune encephalomyelitis (EAE). This is dependent on the capacity of transplanted NPCs to engage concurrent mechanisms of action within specific microenvironments in vivo. Among a wide range of therapeutic actions alternative to cell replacement, neuroprotective and immune modulatory capacities of transplanted NPCs have been described. However, lacking is a detailed understanding of the mechanisms by which NPCs exert their therapeutic plasticity. This study was designed to identify the first candidate that exemplifies and sustains the immune modulatory capacity of transplanted NPCs.To achieve the exclusive targeting of the peripheral immune system, SJL mice with PLP-induced EAE were injected subcutaneously with NPCs and the treatment commenced prior to disease onset. NPC-injected EAE mice showed significant clinical improvement, as compared to controls. Exogenous NPCs lacking the expression of major neural antigens were reliably (and for long-term) found at the level of draining lymph nodes, while establishing sophisticated anatomical interactions with lymph node cells. Importantly, injected NPCs were never found in organs other than lymph nodes, including the brain and the spinal cord. Draining lymph nodes from transplanted mice showed focal up-regulation of major developmental stem cell regulators, such as BMP-4, Noggin and Sonic hedgehog. In lymph nodes, injected NPCs hampered the activation of myeloid dendritic cells (DCs) and steadily restrained the expansion of antigen-specific encephalitogenic T cells. Both ex vivo and in vitro experiments identified a novel highly NPC-specific–BMP-4-dependent–mechanism hindering the DC maturation.The study described herein, identifies the first member of the TGF β/BMP family of stem cell regulators as a novel tolerogenic factor released by NPCs. Full exploitation of this pathway as an efficient tool for vaccination therapy in autoimmune inflammatory conditions is underway

Messa a punto di una via sintetica per l'ottenimento di didesossiribosi fluorometil sostituti e di alcuni nucleosidi pirimidinici, potenziali agenti antivirali

Dottorato di ricerca in chimica industriale. 8. ciclo. A.a. 1992-95. Relatore P. Bravo. Coordinatore F. MinisciConsiglio Nazionale delle Ricerche - Biblioteca Centrale - P.le Aldo Moro, 7, Rome; Biblioteca Nazionale Centrale - P.za Cavalleggeri, 1, Florence / CNR - Consiglio Nazionale delle RichercheSIGLEITItal

Delayed post-ischaemic neuroprotection following systemic neural stem cell transplantation involves multiple mechanisms

Recent evidence suggests that neural stem/precursor cells (NPCs) promote recovery in animal models with delayed neuronal death via a number of indirect bystander effects. A comprehensive knowledge of how transplanted NPCs exert their therapeutic effects is still lacking. Here, we investigated the effects of a delayed transplantation of adult syngenic NPCs—injected intravenously 72 h after transient middle cerebral artery occlusion—on neurological recovery, histopathology and gene expression. NPC-transplanted mice showed a significantly improved recovery from 18 days post-transplantation (dpt) onwards, which persisted throughout the study. A small percentage of injected NPCs accumulated in the brain, integrating mainly in the infarct boundary zone, where most of the NPCs remained undifferentiated up to 30 dpt. Histopathological analysis revealed a hitherto unreported very delayed neuroprotective effect of NPCs, becoming evident at 10 and 30 dpt. Tissue survival was associated with downregulation of markers of inflammation, glial scar formation and neuronal apoptotic death at both mRNA and protein levels. Our data highlight the relevance of very delayed degenerative processes in the stroke brain that are intimately associated with inflammatory and glial responses. These processes may efficaciously be antagonized by (stem) cell-based strategies at time-points far beyond established therapeutic windows for pharmacological neuroprotectio

Transplanted neural stem/precursor cells instruct phagocytes and reduce secondary tissue damage in the injured spinal cord

Transplanted neural stem/precursor cells possess peculiar therapeutic plasticity and can simultaneously instruct several therapeutic mechanisms in addition to cell replacement. Here, we interrogated the therapeutic plasticity of neural stem/precursor cells after their focal implantation in the severely contused spinal cord. We injected syngeneic neural stem/precursor cells at the proximal and distal ends of the contused mouse spinal cord and analysed locomotor functions and relevant secondary pathological events in the mice, cell fate of transplanted neural stem/precursor cells, and gene expression and inflammatory cell infiltration at the injured site. We used two different doses of neural stem/precursor cells and two treatment schedules, either subacute (7 days) or early chronic (21 days) neural stem/precursor cell transplantation after the induction of experimental thoracic severe spinal cord injury. Only the subacute transplant of neural stem/precursor cells enhanced the recovery of locomotor functions of mice with spinal cord injury. Transplanted neural stem/precursor cells survived undifferentiated at the level of the peri-lesion environment and established contacts with endogenous phagocytes via cellular-junctional coupling. This was associated with significant modulation of the expression levels of important inflammatory cell transcripts in vivo. Transplanted neural stem/precursor cells skewed the inflammatory cell infiltrate at the injured site by reducing the proportion of 'classically-activated' (M1-like) macrophages, while promoting the healing of the injured cord. We here identify a precise window of opportunity for the treatment of complex spinal cord injuries with therapeutically plastic somatic stem cells, and suggest that neural stem/precursor cells have the ability to re-programme the local inflammatory cell microenvironment from a 'hostile' to an 'instructive' role, thus facilitating the healing or regeneration past the lesion