BMPRⅡ^(+)neural precursor cells isolated and characterized from organotypic neurospheres:an in vitro model of human fetal spinal cord development

Roof plate secretion of bone morphogenetic proteins(BMPs)directs the cellular fate of sensory neurons during spinal cord development,including the formation of the ascending sensory columns,though their biology is not well understood.Type-ⅡBMP receptor(BMPRⅡ),the cognate receptor,is expressed by neural precursor cells during embryogenesis;however,an in vitro method of enriching BMPRⅡ^(+)human neural precursor cells(hNPCs)from the fetal spinal cord is absent.Immunofluorescence was undertaken on intact second-trimester human fetal spinal cord using antibodies to BMPRⅡand leukemia inhibitory factor(LIF).Regions of highest BMPRⅡ^(+)immunofluorescence localized to sensory columns.Parenchymal and meningeal-associated BMPRⅡ^(+)vascular cells were identified in both intact fetal spinal cord and cortex by co-positivity with vascular lineage markers,CD34/CD39.LIF immunostaining identified a population of somas concentrated in dorsal and ventral horn interneurons,mirroring the expression of LIF receptor/CD118.A combination of LIF supplementation and high-density culture maintained culture growth beyond 10 passages,while synergistically increasing the proportion of neurospheres with a stratified,cytoarchitecture.These neurospheres were characterized by BMPRⅡ^(+)/MAP2ab^(+/–)/βⅢ-tubulin^(+)/nestin^(–)/vimentin^(–)/GFAP^(–)/NeuN^(–)surface hNPCs surrounding a heterogeneous core ofβⅢ-tubulin^(+)/nestin^(+)/vimentin^(+)/GFAP^(+)/MAP2ab^(–)/NeuN^(–)multipotent precursors.Dissociated cultures from tripotential neurospheres contained neuronal(βⅢ-tubulin^(+)),astrocytic(GFAP+),and oligodendrocytic(O4+)lineage cells.Fluorescence-activated cell sorting-sorted BMPRⅡ^(+)hNPCs were MAP2ab^(+/–)/βⅢ-tubulin^(+)/GFAP^(–)/O4^(–)in culture.This is the first isolation of BMPRⅡ^(+)hNPCs identified and characterized in human fetal spinal cords.Our data show that LIF combines synergistically with high-density reaggregate cultures to support the organotypic reorganization of neurospheres,characterized by surface BMPRⅡ^(+)hNPCs.Our study has provided a new methodology for an in vitro model capable of amplifying human fetal spinal cord cell numbers for>10 passages.Investigations of the role BMPRⅡplays in spinal cord development have primarily relied upon mouse and rat models,with interpolations to human development being derived through inference.Because of significant species differences between murine biology and human,including anatomical dissimilarities in central nervous system(CNS)structure,the findings made in murine models cannot be presumed to apply to human spinal cord development.For these reasons,our human in vitro model offers a novel tool to better understand neurodevelopmental pathways,including BMP signaling,as well as spinal cord injury research and testing drug therapies.

The Occurrence of Migraine Auras and Possible Triggers

Our aim is to determine the cause(s) of migraine auras. Our understanding of how migraines and migraine auras originate is very imperfect. An important observation is that migraines occur more frequently in women at reproductive age than in men at a similar age. This suggests that gonadal hormones may be relevant triggers. The occurrence of classical (typical auras without headache) auras in one author (WB) has been recorded. Every aura in six years (85) has been noted, studied and analysed statistically. The auras occur predominantly in Spring and Autumn, especially in the longer reproductive season of Spring. This association is supported statistically. The results support the idea of gonadal hormones as relevant triggers, the strongest candidate being estrogen. Basic mechanisms underlying the auras are discussed, especially the phenomenon of cortical spreading depression. We also propose that both auras and migraines depend upon previous injury to the head or to the brain, giving rise to a condition of “deafferentation hypersensitivity”.

P2X7 receptor signaling during adult hippocampal neurogenesis

Neurogenesis is a persistent and essential feature of the adult mammalian hippocampus.Granular neurons generated from resident pools of stem or progenitor cells provide a mechanism for the formation and consolidation of new memories.Regulation of hippocampal neurogenesis is complex and multifaceted,and numerous signaling pathways converge to modulate cell proliferation,apoptosis,and clearance of cellular debris,as well as synaptic integration of newborn immature neurons.The expression of functional P2X7 receptors in the central nervous system has attracted much interest and the regulatory role of this purinergic receptor during adult neurogenesis has only recently begun to be explored.P2X7 receptors are exceptionally versatile:in their canonical role they act as adenosine triphosphate-gated calcium channels and facilitate calcium-signaling cascades exerting control over the cell via calcium-encoded sensory proteins and transcription factor activation.P2X7 also mediates transmembrane pore formation to regulate cytokine release and facilitate extracellular communication,and when persistently stimulated by high extracellular adenosine triphosphate levels large P2X7 pores form,which induce apoptotic cell death through cytosolic ion dysregulation.Lastly,as a scavenger receptor P2X7 directly facilitates phagocytosis of the cellular debris that arises during neurogenesis,as well as during some disease states.Understanding how P2X7 receptors regulate the physiology of stem and progenitor cells in the adult hippocampus is an important step towards developing useful therapeutic models for regenerative medicine.This review considers the relevant aspects of adult hippocampal neurogenesis and explores how P2X7 receptor activity may influence the molecular physiology of the hippocampus,and neural stem and progenitor cells.

Tackling dipeptidyl peptidase Ⅳ in neurological disorders

Dipeptidyl peptidase IV （DPP-IV） is a serine protease best known for its role in inactivating glucagon-like peptide-1 （GLP-1）, pituitary adenylate cyclase-activating polypeptide （PACAP） and glucose-dependent insulinotropic peptide （GIP）, three stimulators of pancreatic insulin secretion with beneficial effects on glucose disposal. Owing to the relationship between DPP-IV and these peptides, inhibition of DPP-IV enzyme activity is considered as an attractive treatment option for diabetic patients. Nonetheless, increasing studies support the idea that DPP-IV might also be involved in the development of neurological disorders with a neuroinflammatory component, potentially through its non-incretin activities on immune cells. In this review article, we aim at highlighting recent literature describing the therapeutic value of DPP-IV inhibitors for the treatment of such neurological conditions. Finally, we will illustrate some of the promising results obtained using berberine, a plant extract with potent inhibitory activity on DPP-IV.