RESUMEN
The pathogenesis of Parkinson's disease (PD) is characterized by progressive deposition of alpha-synuclein (α-syn) aggregates in dopaminergic neurons and neuroinflammation. Noninvasive in vivo imaging of α-syn aggregate accumulation and neuroinflammation can elicit the underlying mechanisms involved in disease progression and facilitate the development of effective treatment as well as disease diagnosis and prognosis. Here we present a novel approach to simultaneously profile α-syn aggregation and reactive microgliosis in vivo, by targeting oligomeric α-syn in cerebrospinal fluid with nanoparticle bearing a magnetic resonance imaging (MRI), contrast payload. In this proof-of-concept report we demonstrate, in vitro, that microglia and neuroblastoma cell lines internalize agglomerates formed by cross-linking the nanoparticles with oligomeric α-syn. Delayed in vivo MRI scans following intravenous administration of the nanoparticles in the M83 α-syn transgenic mouse line show statistically significant MR signal enhancement in test mice versus controls. The in vivo data were validated by ex-vivo immunohistochemical analysis which show strong correlation between in vivo MRI signal enhancement, Lewy pathology distribution, and microglia activity in the treated brain tissue. Furthermore, neuronal and microglial cells in brain tissue from treated mice display strong cytosolic signal originating from the nanoparticles, attributed to in vivo cell uptake of nanoparticle/oligomeric α-syn agglomerates.
RESUMEN
Alzheimer's disease is the most common cause of dementia and a leading cause of mortality in the elderly population. Diagnosis of Alzheimer's disease has traditionally relied on evaluation of clinical symptoms for cognitive impairment with a definitive diagnosis requiring post-mortem demonstration of neuropathology. However, advances in disease pathogenesis have revealed that patients exhibit Alzheimer's disease pathology several decades before the manifestation of clinical symptoms. Magnetic resonance imaging (MRI) plays an important role in the management of patients with Alzheimer's disease. The clinical availability of molecular MRI (mMRI) contrast agents can revolutionize the diagnosis of Alzheimer's disease. In this article, we review advances in nanoparticle contrast agents, also referred to as nanoprobes, for mMRI of Alzheimer's disease. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.
Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Humanos , Anciano , Enfermedad de Alzheimer/diagnóstico por imagen , Medios de Contraste , Tomografía de Emisión de Positrones/métodos , Disfunción Cognitiva/patología , Imagen por Resonancia Magnética/métodos , Encéfalo/diagnóstico por imagen , Encéfalo/patologíaRESUMEN
The first line of treatment for most solid tumors is surgical resection of the primary tumor with adequate negative margins. Incomplete tumor resections with positive margins account for over 75% of local recurrences and the development of distant metastases. In cases of oral cavity squamous cell carcinoma (OSCC), the rate of successful tumor removal with adequate margins is just 50-75%. Advanced real-time imaging methods that improve the detection of tumor margins can help improve success rates,overall safety, and reduce the cost. Fluorescence imaging in the second near-infrared (NIR-II) window has the potential to revolutionize the field due to its high spatial resolution, low background signal, and deep tissue penetration properties, but NIR-II dyes with adequate in vivo performance and safety profiles are scarce. A novel NIR-II fluorophore, XW-03-66, with a fluorescence quantum yield (QY) of 6.0% in aqueous media is reported. XW-03-66 self-assembles into nanoparticles (≈80 nm) and has a systemic circulation half-life (t1/2 ) of 11.3 h. In mouse models of human papillomavirus (HPV)+ and HPV- OSCC, XW-03-66 outperformed indocyanine green (ICG), a clinically available NIR dye, and enabled intraoperative NIR-II image-guided resection of the tumor and adjacent draining lymph node with negative margins. In vitro and in vivo toxicity assessments revealed minimal safety concerns for in vivo applications.
Asunto(s)
Neoplasias de la Boca , Infecciones por Papillomavirus , Ratones , Animales , Humanos , Espectroscopía Infrarroja Corta/métodos , Verde de Indocianina , Colorantes Fluorescentes/química , Neoplasias de la Boca/diagnóstico por imagen , Neoplasias de la Boca/cirugíaRESUMEN
INTRODUCTION: Prior preclinical studies established the utility of liposomal nanoparticle blood-pool contrast agents in visualizing the retroplacental clear space (RPCS), a marker of normal placentation, while sparing fetuses from exposure because the agent does not cross the placental barrier. In this work, we characterized RPCS disruption in a mouse model of placenta accreta spectrum (PAS) using these agents. MATERIALS AND METHODS: Contrast-enhanced MRI (CE-MRI) and computed tomography (CE-CT) using liposomal nanoparticles bearing gadolinium (liposomal-Gd) and iodine were performed in pregnant Gab3-/- and wild type (WT) mice at day 16 of gestation. CE-MRI was performed on a 1T scanner using a 2D T1-weighted sequence (100×100×600 µm3 voxels) and CE-CT was performed at a higher resolution (70×70×70 µm3 voxels). Animals were euthanized post-imaging and feto-placental units (FPUs) were harvested for histological examination. RPCS conspicuity was scored through blinded assessment of images. RESULTS: Pregnant Gab3-/- mice showed elevated rates of complicated pregnancy. Contrast-enhanced imaging demonstrated frank infiltration of the RPCS of Gab3-/- FPUs. RPCS in Gab3-/- FPUs was smaller in volume, demonstrated a heterogeneous signal profile, and received lower conspicuity scores than WT FPUs. Histology confirmed in vivo findings and demonstrated staining consistent with a thinner RPCS in Gab3-/- FPUs. DISCUSSION: Imaging of the Gab3-/- mouse model at late gestation with liposomal contrast agents enabled in vivo characterization of morphological differences in the RPCS that could cause the observed pregnancy complications. An MRI-based method for visualizing the RPCS would be valuable for early detection of invasive placentation.
Asunto(s)
Nanopartículas , Placenta , Femenino , Embarazo , Animales , Ratones , Placenta/diagnóstico por imagen , Medios de Contraste , Imagen por Resonancia Magnética , Modelos Animales de Enfermedad , Estudios Retrospectivos , Proteínas Adaptadoras Transductoras de SeñalesRESUMEN
The abnormal phosphorylation of tau is a necessary precursor to the formation of tau fibrils, a marker of Alzheimer's disease. We hypothesize that hyperphosphorylative conditions may result in unique cell surface markers. We identify and demonstrate the utility of such surrogate markers to identify the hyperphosphorylative state. Methods: Cell SELEX was used to identify novel thioaptamers specifically binding hyperphosphorylative cells. Cell surface vimentin was identified as a potential binding target of the aptamer. Novel molecular magnetic resonance imaging (M-MRI) probes using these aptamers and a small molecule ligand to vimentin were used for in vivo detection of this pre-pathological state. Results: In a mouse model of pathological tau, we demonstrated in vivo visualization of the hyperphosphorylative state by M-MRI, enabling the identification at a pre-pathological stage of mice that develop frank tau pathology several months later. In vivo visualization of the hyperphosphorylative state by M-MRI was further validated in a second mouse model (APP/PS1) of Alzheimer's disease again identifying the mutants at a pre-pathological stage. Conclusions: M-MRI of the hyperphosphorylative state identifies future tau pathology and could enable extremely early-stage diagnosis of Alzheimer's disease, at a pre-patholgical stage.
Asunto(s)
Enfermedad de Alzheimer , Enfermedad de Alzheimer/patología , Animales , Biomarcadores , Modelos Animales de Enfermedad , Imagen por Resonancia Magnética , Ratones , Ratones Transgénicos , Vimentina , Proteínas tau/metabolismoRESUMEN
Atheromatous lesions are characterized by intrusion into the vascular lumen, resulting in morphological changes to the blood compartment and into the vessel wall, resulting in characteristic molecular and cellular signatures in the solid tissue of the intima, tunica media, adventitia and surrounding tissue. Nanoprobes can be easily formulated to provide long blood-pool residence and molecular targeting, facilitating the imaging of atheromatous changes. Detection of nanoprobes can be accomplished by a variety of methods. We focus in this chapter on the use of cross-sectional imaging techniques, computed tomography (CT) and magnetic resonance imaging (MRI), that facilitate in vivo, noninvasive imaging of the vascular morphology and molecular/cellular signatures of the atheroma. The methods described are suitable for use in animal models, although versions of the probes are being readied for clinical trials, potentially facilitating clinical use in the future.
Asunto(s)
Aterosclerosis , Placa Aterosclerótica , Adventicia/patología , Animales , Aterosclerosis/patología , Imagen por Resonancia Magnética/métodos , Placa Aterosclerótica/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
The development of imaging agents for inâ vivo detection of alpha-synuclein (α-syn) pathologies faces several challenges. A major gap in the field is the lack of diverse molecular scaffolds with high affinity and selectivity to α-syn fibrils for inâ vitro screening assays. Better inâ vitro scaffolds can instruct the discovery of better inâ vivo agents. We report the rational design, synthesis, and inâ vitro evaluation of a series of novel 1-indanone and 1,3-indandione derivatives from a Structure-Activity Relationship (SAR) study centered on some existing α-syn fibril binding ligands. Our results from fibril saturation binding experiments show that two of the lead candidates compounds 8 and 32 bind α-syn fibrils with binding constants (Kd ) of 9.0 and 18.8â nM, respectively, and selectivity of greater than 10× for α-syn fibrils compared with amyloid-ß (Aß) and tau fibrils. Our results demonstrate that the lead ligands avidly label all forms of α-syn on PD brain tissue sections, but only the dense core of senile plaques in AD brain tissue, respectively. These results are corroborated by ligand-antibody colocalization data from Syn211, which shows immunoreactivity toward all forms of α-syn aggregates, and Syn303, which displays preferential reactivity toward mature Lewy pathology. Our results reveal that 1-indanone derivatives have desirable properties for the biological evaluation of α-synucleinopathies.
Asunto(s)
Enfermedad de Alzheimer/tratamiento farmacológico , Indanos/farmacología , Fármacos Neuroprotectores/farmacología , alfa-Sinucleína/antagonistas & inhibidores , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Relación Dosis-Respuesta a Droga , Diseño de Fármacos , Humanos , Indanos/síntesis química , Indanos/química , Ligandos , Estructura Molecular , Fármacos Neuroprotectores/síntesis química , Fármacos Neuroprotectores/química , Agregado de Proteínas/efectos de los fármacos , Pliegue de Proteína/efectos de los fármacos , Relación Estructura-Actividad , alfa-Sinucleína/metabolismoRESUMEN
[Figure: see text].
Asunto(s)
Aorta/diagnóstico por imagen , Aneurisma de la Aorta/diagnóstico por imagen , Disección Aórtica/diagnóstico por imagen , Rotura de la Aorta/diagnóstico por imagen , Aortografía , Angiografía por Tomografía Computarizada , Medios de Contraste , Nanopartículas , Ácidos Triyodobenzoicos , Microtomografía por Rayos X , Disección Aórtica/inducido químicamente , Disección Aórtica/patología , Angiotensina II , Animales , Aorta/patología , Aneurisma de la Aorta/inducido químicamente , Aneurisma de la Aorta/patología , Rotura de la Aorta/inducido químicamente , Rotura de la Aorta/patología , Dieta Alta en Grasa , Dilatación Patológica , Modelos Animales de Enfermedad , Progresión de la Enfermedad , Diagnóstico Precoz , Masculino , Ratones Endogámicos C57BL , Valor Predictivo de las Pruebas , Factores de TiempoRESUMEN
In these preclinical studies, we describe ADx-001, an Aß-targeted liposomal macrocyclic gadolinium (Gd) imaging agent, for MRI of amyloid plaques. The targeting moiety is a novel lipid-PEG conjugated styryl-pyrimidine. An MRI-based contrast agent such as ADx-001 is attractive because of the lack of radioactivity, ease of distribution, long shelf life, and the prevalence of MRI scanners. Dose-ranging efficacy studies were performed on a 1 T MRI scanner using a transgenic APP/PSEN1 mouse model of Alzheimer's disease. ADx-001 was tested at 0.10, 0.15, and 0.20 mmol Gd/kg. Gold standard post-mortem amyloid immunostaining was used for the determination of sensitivity and specificity. ADx-001 toxicity was evaluated in rats and monkeys at doses up to 0.30 mmol Gd/kg. ADx-001 pharmacokinetics were determined in monkeys and its tissue distribution was evaluated in rats. ADx-001-enhanced MRI demonstrated significantly higher (p < 0.05) brain signal enhancement in transgenic mice relative to wild type mice at all dose levels. ADx-001 demonstrated high sensitivity at 0.20 and 0.15 mmol Gd/kg and excellent specificity at all dose levels for in vivo imaging of ß amyloid plaques. ADx-001 was well tolerated in rats and monkeys and exhibited the slow clearance from circulation and tissue biodistribution typical of PEGylated nanoparticles.
Asunto(s)
Enfermedad de Alzheimer/diagnóstico por imagen , Amiloide/metabolismo , Medios de Contraste/administración & dosificación , Imagen por Resonancia Magnética/métodos , Placa Amiloide/diagnóstico por imagen , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/genética , Animales , Medios de Contraste/farmacocinética , Modelos Animales de Enfermedad , Relación Dosis-Respuesta a Droga , Humanos , Macaca fascicularis , Masculino , Ratones , Ratones Transgénicos , Fragmentos de Péptidos/metabolismo , Placa Amiloide/genética , Placa Amiloide/metabolismo , Presenilina-1/genética , Ratas , Distribución TisularRESUMEN
Non-invasive methods for estimating placental fractional blood volume (FBV) are of great interest for characterization of vascular perfusion in placentae during pregnancy to identify placental insufficiency that may be indicative of local ischemia or fetal growth restriction (FGR). Nanoparticle contrast-enhanced magnetic resonance imaging (CE-MRI) may enable direct placental FBV estimation and may provide a reliable, 3D alternative to assess maternal-side placental perfusion. In this pre-clinical study, we investigated if placental FBV at 14, 16, and 18 days of gestation could be estimated through contrast-enhanced MRI using a long circulating blood-pool liposomal gadolinium contrast agent that does not penetrate the placental barrier. Placental FBV estimates of 0.47 ± 0.06 (E14.5), 0.50 ± 0.04 (E16.5), and 0.52 ± 0.04 (E18.5) were found through fitting pre-contrast and post-contrast T1 values in placental tissue using a variable flip angle method. MRI-derived placental FBV was validated against nanoparticle contrast-enhanced computed tomography (CE-CT) derived placental FBV, where signal is directly proportional to the concentration of iodine contrast agent. The results demonstrate successful estimation of the placental FBV, with values statistically indistinguishable from the CT derived values.
Asunto(s)
Medios de Contraste/metabolismo , Placenta/irrigación sanguínea , Placenta/diagnóstico por imagen , Animales , Volumen Sanguíneo , Femenino , Gadolinio , Liposomas , Imagen por Resonancia Magnética/métodos , Ratones , Ratones Endogámicos C57BL , Nanopartículas , Placenta/metabolismo , EmbarazoRESUMEN
INTRODUCTION: Visualization of the retroplacental clear space (RPCS) may provide critical insight into the development of abnormally invasive placenta (AIP). In this pre-clinical study, we characterized the appearance of the RPCS on magnetic resonance imaging (MRI) during the second half of gestation using a liposomal gadolinium contrast agent (liposomal-Gd). MATERIALS AND METHODS: Studies were performed in fifteen pregnant C57BL/6 mice at 10, 12, 14, 16, and 18 days of gestation. MRI was performed on a 1T permanent magnet scanner. Pre-contrast and post-contrast images were acquired using T1-weighted gradient-recalled echo (T1w-GRE) and T2-weighted fast spin echo (T2w-FSE) sequences. Animals were euthanized after imaging and feto-placental units harvested for histological examination. Visualization of the RPCS was scored by a maternal-fetal radiologist and quantified by measuring the contrast-to-noise ratio (CNR) on T1w images. Feto-placental features were segmented for analysis of volumetric changes during gestation. RESULTS: Contrast-enhanced T1w images enabled the visualization of structural changes in placental development between days 10-18 of gestation. Although the placental margin on the fetal side was clearly visible at all time points, the RPCS was partially visible at day 10 of gestation, and clearly visible by day 12. Hematoxylin and eosin (H&E) staining of the placental tissue corroborated MRI findings of structural and morphological changes in the placenta. CONCLUSIONS: Contrast-enhanced MR imaging using liposomal-Gd enabled adequate visualization of the retroplacental clear space starting at day 12 of gestation. The agent also enabled characterization of placental structure and morphological changes through gestation.
Asunto(s)
Imagen por Resonancia Magnética/métodos , Placenta/diagnóstico por imagen , Animales , Medios de Contraste , Femenino , Gadolinio , Edad Gestacional , Liposomas , Ratones , Ratones Endogámicos C57BL , Modelos Animales , Placenta/anatomía & histología , Placentación , EmbarazoRESUMEN
Fluorine-19 (19F) magnetic resonance imaging (MRI) has the potential for a wide range of in vivo applications but is limited by lack of flexibility in exogenous probe formulation. Most 19F MRI probes are composed of perfluorocarbons (PFCs) or perfluoropolyethers (PFPEs) with intrinsic properties which limit formulation options. Hydrophilic organofluorine molecules can provide more flexibility in formulation options. We report herein a hyperfluorinated hydrophilic organoflourine, ET1084, with â¼24 wt. % 19F content. It dissolves in water and aqueous buffers to give solutions with ≥8 M 19F. 19F MRI phantom studies at 9.4T employing a 10-minute multislice multiecho (MSME) scan sequence show a linear increase in signal-to-noise ratio (SNR) with increasing concentrations of the molecule and a detection limit of 5 mM. Preliminary cytotoxicity and genotoxicity assessments suggest it is safe at concentrations of up to 20 mM.
Asunto(s)
Medios de Contraste/química , Flúor , Fluorocarburos/química , Imagen por Resonancia Magnética/métodos , Medios de Contraste/toxicidad , Fluorocarburos/toxicidad , Interacciones Hidrofóbicas e Hidrofílicas , Límite de Detección , Fantasmas de Imagen , Relación Señal-Ruido , SolubilidadRESUMEN
Inflammation drives the degradation of atherosclerotic plaque, yet there are no non-invasive techniques available for imaging overall inflammation in atherosclerotic plaques, especially in the coronary arteries. To address this, we have developed a clinically relevant system to image overall inflammatory cell burden in plaque. Here, we describe a targeted contrast agent (THI0567-targeted liposomal-Gd) that is suitable for magnetic resonance (MR) imaging and binds with high affinity and selectivity to the integrin α4ß1(very late antigen-4, VLA-4), a key integrin involved in recruiting inflammatory cells to atherosclerotic plaques. This liposomal contrast agent has a high T1 relaxivity (~2 × 105 mM-1s-1 on a particle basis) resulting in the ability to image liposomes at a clinically relevant MR field strength. We were able to visualize atherosclerotic plaques in various regions of the aorta in atherosclerosis-prone ApoE-/- mice on a 1 Tesla small animal MRI scanner. These enhanced signals corresponded to the accumulation of monocyte/macrophages in the subendothelial layer of atherosclerotic plaques in vivo, whereas non-targeted liposomal nanoparticles did not demonstrate comparable signal enhancement. An inflammatory cell-targeted method that has the specificity and sensitivity to measure the inflammatory burden of a plaque could be used to noninvasively identify patients at risk of an acute ischemic event.
Asunto(s)
Integrina alfa4beta1/química , Integrina alfa4beta1/metabolismo , Imagen por Resonancia Magnética , Placa Aterosclerótica/diagnóstico por imagen , Placa Aterosclerótica/metabolismo , Animales , Modelos Animales de Enfermedad , Integrina alfa4beta1/antagonistas & inhibidores , Ligandos , Liposomas , Imagen por Resonancia Magnética/métodos , Ratones , Ratones Noqueados , Modelos Moleculares , Conformación Molecular , Placa Aterosclerótica/patología , Unión Proteica , Relación Estructura-ActividadRESUMEN
Fluorine-19 (19F) Magnetic Resonance Imaging (MRI) is an emerging modality for molecular imaging and cell tracking. The hydrophobicity of current exogenous probes, perfluorocarbons (PFCs) and perfluoropolyethers (PFPEs), limits the formulation options available for in vivo applications. Hydrophilic probes permit more formulation flexibility. Further, the broad Nuclear Magnetic Resonance (NMR) chemical shift range of organofluorine species enables multiple probes with unique 19F MR signatures for simultaneous interrogation of distinct molecular targets in vivo. We report herein a flexible approach to stable liposomal formulations of hydrophilic fluorinated molecules (each bearing numerous magnetically equivalent 19F atoms), with 19F encapsulation of up to 22.7 mg/mL and a per particle load of 3.6 × 106 19F atoms. Using a combination of such probes, we demonstrate, with no chemical shift artifacts, the simultaneous imaging of multiple targets within a given target volume by spectral 19F MRI.
Asunto(s)
Éteres/química , Imagen por Resonancia Magnética con Fluor-19 , Fluorocarburos/química , Interacciones Hidrofóbicas e HidrofílicasRESUMEN
Amyloid binding molecules with greater hydrophilicity than existing ligands were synthesized. The lead candidate ET6-21 bound amyloid fibrils, and amyloid deposits in dog brain and human brain tissue ex vivo. The ligand was used to prepare novel amyloid-targeted liposomal nanoparticles. The preparation was tested in the Tg2576 and TetO/APP mouse models of amyloid deposition. Gd chelates and Indocyanine green were included in the particles for visualization by MRI and near-infrared microscopy. Upon intravenous injection, the particles successfully traversed the blood-brain barrier in these mice, and bound to the plaques. Magnetic resonance imaging (T1-MRI) conducted 4 days after injection demonstrated elevated signal in the brains of mice with amyloid plaques present. No signal was observed in amyloid-negative mice, or in amyloid-positive mice injected with an untargeted version of the same agent. The MRI results were confirmed by immunohistochemical and fluorescent microscopic examination of mouse brain sections, showing colocalization of the fluorescent tags and amyloid deposits.
Asunto(s)
Liposomas/metabolismo , Imagen por Resonancia Magnética/métodos , Nanopartículas/metabolismo , Placa Amiloide/diagnóstico por imagen , Animales , Encéfalo/diagnóstico por imagen , Ratones , Neuroimagen/métodosRESUMEN
In Alzheimer's disease (AD), there is increasing evidence of blood-brain barrier (BBB) compromise, usually observed as 'microbleeds' correlated with amyloid plaque deposition and apoE-É4 status, raising the possibility of nanotherapeutic delivery. Molecular probes have been used to study neurovascular leak, but this approach does not adequately estimate vascular permeability of nanoparticles. We therefore characterized cerebrovascular leaks in live APP+ transgenic animals using a long circulating â¼100 nm nanoparticle computed tomography (CT) contrast agent probe. Active leaks fell into four categories: (1) around the dorsomedial cerebellar artery (DMCA), (2) around other major vessels, (3) nodular leaks in the cerebral cortex, and (4) diffuse leaks. Cortical leaks were uniformly more frequent in the transgenic animals than in age-matched controls. Leaks around vessels other than the DMCA were more frequent in older transgenics compared with younger ones. All other leaks were equally prevalent across genotypes independent of age. Ten days after injection, 4 to 5 µg of the dose was estimated to be present in the brain, roughly a half of which was in locations other than the leaky choroid plexus, and associated with amyloid deposition in older animals. These results suggest that amyloid deposition and age increase delivery of nanoparticle-borne reagents to the brain, in therapeutically relevant amounts.
Asunto(s)
Amiloide/análisis , Barrera Hematoencefálica/patología , Encéfalo/irrigación sanguínea , Angiopatía Amiloide Cerebral/patología , Arterias Cerebrales/patología , Precursor de Proteína beta-Amiloide/genética , Animales , Encéfalo/patología , Angiopatía Amiloide Cerebral/genética , Medios de Contraste , Modelos Animales de Enfermedad , Femenino , Humanos , Masculino , Ratones , Ratones Transgénicos , Nanopartículas , Tomografía Computarizada por Rayos XRESUMEN
Extracellular amyloid-ß (Aß) plaques and intracellular neurofibrillary tangles constitute the major neuropathological hallmarks of Alzheimer's disease (AD). It is now apparent that parenchymal Aß plaque deposition precedes behavioral signs of disease by several years. The development of agents that can target these plaques may be useful as diagnostic or therapeutic tools. In this study, we synthesized an Aß-targeted lipid conjugate, incorporated it in stealth liposomal nanoparticles and tested their ability to bind amyloid plaque deposits in an AD mouse model. The results show that the particles maintain binding profiles to synthetic Aß aggregates comparable to the free ligand, and selectively bind Aß plaque deposits in brain tissue sections of an AD mouse model (APP/PSEN1 transgenic mice) with high efficiency. When administered intravenously, these long circulating nanoparticles appear to cross the blood-brain barrier and bind to Aß plaque deposits, labeling parenchymal amyloid deposits and vascular amyloid characteristic of cerebral amyloid angiopathy.
Asunto(s)
Enfermedad de Alzheimer/genética , Péptidos beta-Amiloides/administración & dosificación , Precursor de Proteína beta-Amiloide/genética , Presenilina-1/genética , Administración Intravenosa , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Péptidos beta-Amiloides/química , Precursor de Proteína beta-Amiloide/metabolismo , Animales , Barrera Hematoencefálica/metabolismo , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Modelos Animales de Enfermedad , Hipocampo/metabolismo , Hipocampo/patología , Liposomas/química , Ratones , Ratones Transgénicos , Fosfatidiletanolaminas , Placa Amiloide , Polietilenglicoles , Presenilina-1/metabolismo , Unión ProteicaRESUMEN
Boronic acids, known to bind diols, were screened to identify non-inflammatory cross-linkers for the preparation of glucose sensitive and insulin releasing agglomerates of liposomes (Agglomerated Vesicle Technology-AVT). This was done in order to select a suitable replacement for the previously used cross-linker, ConcanavalinA (ConA), a lectin known to have both toxic and inflammatory effects in vivo. Lead-compounds were selected from screens that involved testing for inflammatory potential, cytotoxicity and glucose-binding. These were then conjugated to insulin-encapsulating nanoparticles and agglomerated via sugar-boronate ester linkages to form AVTs. In vitro, the particles demonstrated triggered release of insulin upon exposure to physiologically relevant concentrations of glucose (10 mmoles/L-40 mmoles/L). The agglomerates were also shown to be responsive to multiple spikes in glucose levels over several hours, releasing insulin at a rate defined by the concentration of the glucose trigger.