6 research outputs found
ImmunoPEGliposomes for the targeted delivery of novel lipophilic drugs to red blood cells in a falciparum malaria murine model
Most drugs currently entering the clinical pipeline for severe
malaria therapeutics are of lipophilic nature, with a relatively
poor solubility in plasma and large biodistribution volumes. Low
amounts of these compounds do consequently accumulate in
circulating Plasmodium-infected red blood cells, exhibiting
limited antiparasitic activity. These drawbacks can in principle
be satisfactorily dealt with by stably encapsulating drugs in
targeted nanocarriers. Here this approach has been adapted for
its use in immunocompetent mice infected by the Plasmodium
yoelii 17XL lethal strain, selected as a model for human blood
infections by Plasmodium falciparum. Using immunoliposomes
targeted against a surface protein characteristic of the murine
erythroid lineage, the protocol has been applied to two novel
antimalarial lipophilic drug candidates, an aminoquinoline and
an aminoalcohol. Large encapsulation yields of >90% were
obtained using a citrate-buffered pH gradient method and the
resulting immunoliposomes reached in vivo erythrocyte targeting
and retention efficacies of >80%. In P. yoelii-infected mice,
the immunoliposomized aminoquinoline succeeded in decreasing
blood parasitemia from severe to uncomplicated malaria parasite
densities (i.e. from >/=25% to ca. 5%), whereas the same
amount of drug encapsulated in non-targeted liposomes had no
significant effect on parasite growth. Pharmacokinetic analysis
indicated that this good performance was obtained with a rapid
clearance of immunoliposomes from the circulation (blood
half-life of ca. 2 h), suggesting a potential for improvement of
the proposed model
Reelin regulates the maturation of dendritic spines, synaptogenesis and glial ensheathment of newborn granule cells
The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated. Significance Statement: The extracellular protein Reelin has an important role in neurological diseases, including epilepsy, Alzheimer's disease and psychiatric diseases, targeting hippocampal circuits. Here we address the role of Reelin in the development of synaptic contacts in adult-generated granule cells (GCs), a neuronal population that is crucial for learning and memory and implicated in neurological and psychiatric diseases. We found that the Reelin pathway controls the shapes, sizes, and types of dendritic spines, the complexity of multisynaptic innervations and the degree of the perisynaptic astroglial ensheathment that controls synaptic homeostasis. These findings show a pivotal role of Reelin in GC synaptogenesis and provide a foundation for structural circuit alterations caused by Reelin deregulation that may occur in neurological and psychiatric disorders
ImmunoPEGliposomes for the targeted delivery of novel lipophilic drugs to red blood cells in a falciparum malaria murine model
Most drugs currently entering the clinical pipeline for severe
malaria therapeutics are of lipophilic nature, with a relatively
poor solubility in plasma and large biodistribution volumes. Low
amounts of these compounds do consequently accumulate in
circulating Plasmodium-infected red blood cells, exhibiting
limited antiparasitic activity. These drawbacks can in principle
be satisfactorily dealt with by stably encapsulating drugs in
targeted nanocarriers. Here this approach has been adapted for
its use in immunocompetent mice infected by the Plasmodium
yoelii 17XL lethal strain, selected as a model for human blood
infections by Plasmodium falciparum. Using immunoliposomes
targeted against a surface protein characteristic of the murine
erythroid lineage, the protocol has been applied to two novel
antimalarial lipophilic drug candidates, an aminoquinoline and
an aminoalcohol. Large encapsulation yields of >90% were
obtained using a citrate-buffered pH gradient method and the
resulting immunoliposomes reached in vivo erythrocyte targeting
and retention efficacies of >80%. In P. yoelii-infected mice,
the immunoliposomized aminoquinoline succeeded in decreasing
blood parasitemia from severe to uncomplicated malaria parasite
densities (i.e. from >/=25% to ca. 5%), whereas the same
amount of drug encapsulated in non-targeted liposomes had no
significant effect on parasite growth. Pharmacokinetic analysis
indicated that this good performance was obtained with a rapid
clearance of immunoliposomes from the circulation (blood
half-life of ca. 2 h), suggesting a potential for improvement of
the proposed model
FIB/SEM technology allows highthroughput 3D reconstruction of dendritic spines and synapses in GFP-traced adult-generated neurons
The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3-4 and 8-9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner
Reelin regulates the maturation of dendritic spines, synaptogenesis and glial ensheathment of newborn granule cells
The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated. Significance Statement: The extracellular protein Reelin has an important role in neurological diseases, including epilepsy, Alzheimer's disease and psychiatric diseases, targeting hippocampal circuits. Here we address the role of Reelin in the development of synaptic contacts in adult-generated granule cells (GCs), a neuronal population that is crucial for learning and memory and implicated in neurological and psychiatric diseases. We found that the Reelin pathway controls the shapes, sizes, and types of dendritic spines, the complexity of multisynaptic innervations and the degree of the perisynaptic astroglial ensheathment that controls synaptic homeostasis. These findings show a pivotal role of Reelin in GC synaptogenesis and provide a foundation for structural circuit alterations caused by Reelin deregulation that may occur in neurological and psychiatric disorders
FIB/SEM technology allows highthroughput 3D reconstruction of dendritic spines and synapses in GFP-traced adult-generated neurons
The fine analysis of synaptic contacts is usually performed using transmission electron microscopy (TEM) and its combination with neuronal labeling techniques. However, the complex 3D architecture of neuronal samples calls for their reconstruction from serial sections. Here we show that focused ion beam/scanning electron microscopy (FIB/SEM) allows efficient, complete, and automatic 3D reconstruction of identified dendrites, including their spines and synapses, from GFP/DAB-labeled neurons, with a resolution comparable to that of TEM. We applied this technology to analyze the synaptogenesis of labeled adult-generated granule cells (GCs) in mice. 3D reconstruction of dendritic spines in GCs aged 3-4 and 8-9 weeks revealed two different stages of dendritic spine development and unexpected features of synapse formation, including vacant and branched dendritic spines and presynaptic terminals establishing synapses with up to 10 dendritic spines. Given the reliability, efficiency, and high resolution of FIB/SEM technology and the wide use of DAB in conventional EM, we consider FIB/SEM fundamental for the detailed characterization of identified synaptic contacts in neurons in a high-throughput manner