Monocytes as Carriers of Magnetic Nanoparticles for Tracking Inflammation in the Epileptic Rat Brain

Immune cells: potential carriers or agents for drug delivery to the central nervous system

Drug delivery systems (DDS) have recently emerged as a promising approach for the unique advantages of drug protection and targeted delivery. However, the access of nanoparticles/drugs to the central nervous system (CNS) remains a challenge mainly due to the obstruction from brain barriers. Immune cells infiltrating the CNS in the pathological state have inspired the development of strategies for CNS foundation drug delivery. Herein, we outline the three major brain barriers in the CNS and the mechanisms by which immune cells migrate across the blood-brain barrier. We subsequently review biomimetic strategies utilizing immune cell-based nanoparticles for the delivery of nanoparticles/drugs to the CNS, as well as recent progress in rationally engineering immune cell-based DDS for CNS diseases. Finally, we discuss the challenges and opportunities of immune cell-based DDS in CNS diseases to promote their clinical development.

Cell-Membrane-Coated Nanoparticles for Targeted Drug Delivery to the Brain for the Treatment of Neurological Diseases

Neurological diseases (NDs) are a significant cause of disability and death in the global population. However, effective treatments still need to be improved for most NDs. In recent years, cell-membrane-coated nanoparticles (CMCNPs) as drug-targeting delivery systems have become a research hotspot. Such a membrane-derived, nano drug-delivery system not only contributes to avoiding immune clearance but also endows nanoparticles (NPs) with various cellular and functional mimicries. This review article first provides an overview of the function and mechanism of single/hybrid cell-membrane-derived NPs. Then, we highlight the application and safety of CMCNPs in NDs. Finally, we discuss the challenges and opportunities in the field.

Magnetic labeling of primary murine monocytes using very small superparamagnetic iron oxide nanoparticles

Due to their very small size, nanoparticles can interact with all cells in the central nervous system. One of the most promising nanoparticle subgroups are very small superparamagnetic iron oxide nanoparticles (VSOP) that are citrate coated for electrostatic stabilization. To determine their influence on murine blood-derived monocytes, which easily enter the injured central nervous system, we applied VSOP and carboxydextran-coated superparamagnetic iron oxide nanoparticles (Resovist). We assessed their impact on the viability, cytokine, and chemokine secretion, as well as iron uptake of murine blood-derived monocytes. We found that (1) the monocytes accumulated VSOP and Resovist, (2) this uptake seemed to be nanoparticle- and time-dependent, (3) the decrease of monocytes viability was treatment-related, (4) VSOP and Resovist incubation did not alter cytokine homeostasis, and (5) overall a 6-hour treatment with 0.75 mM VSOP-R1 was probably sufficient to effectively label monocytes for future experiments. Since homeostasis is not altered, it is safe to label blood-derived monocles with VSOP. VSOP labeled monocytes can be used to study injured central nervous system sites further, for example with drug-carrying VSOP.

Soman (GD) Rat Model to Mimic Civilian Exposure to Nerve Agent: Mortality, Video-EEG Based Status Epilepticus Severity, Sex Differences, Spontaneously Recurring Seizures, and Brain Pathology

Modeling a real-world scenario of organophosphate nerve agent (OPNA) exposure is challenging. Military personnel are premedicated with pyridostigmine, which led to the development of OPNA models with pyridostigmine/oxime pretreatment to investigate novel therapeutics for acute and chronic effects. However, civilians are not premedicated with pyridostigmine/oxime. Therefore, experimental models without pyridostigmine were developed by other laboratories though often only in males. Following OPNA exposure, prolonged convulsive seizures (CS) or status epilepticus (SE) are concerning. The duration and severity of CS/SE determine the extent of brain injury in survivors even after treating with medical countermeasures (MCM)/antidotes such as atropine, an oxime, and an anticonvulsant such as diazepam/midazolam. In this study, using a large mixed sex cohort of adult male and female rats, without pretreatment, we demonstrate severe SE lasting for >20 min in 82% of the animals in response to soman (GD,132 μg/kg, s.c.). Atropine sulfate (2 mg/kg, i.m.) and HI-6 (125 mg/kg, i.m.) were administered immediately following soman, and midazolam (3 mg/kg, i.m.) 1 h post-exposure. Immediate MCM treatment is impractical in civilian exposure to civilians, but this approach reduces mortality in experimental models. Interestingly, female rats, irrespective of estrous stages, had an average of 44 min CS (stage ≥ 3), while males had an average of 32 min CS during SE, starting from soman exposure to midazolam treatment. However, in telemetry device implanted groups, there were no significant sex differences in SE severity; males had 40 min and females 43 min of continuous CS until midazolam was administered. No animals died prior to midazolam administration and less than 5% died in the first week after soman intoxication. In telemetered animals, there was a direct correlation between EEG changes and behavioral seizures in real-time. In the long-term, convulsive spontaneously recurring seizures (SRS) were observed in 85% of randomly chosen animals. At 4-months post-soman, the brain histology confirmed reactive gliosis and neurodegeneration. The novel findings of this study are that, in non-telemetered animals, the SE severity following soman intoxication was significantly greater in females compared to males and that the estrous cycle did not influence the response.

Targeting neuroinflammation by intranasal delivery of nanoparticles in neurological diseases: a comprehensive review

Neuroinflammation (NIF) plays an essential role in the pathology of neurological disorders like Parkinson's disease, Alzheimer's disease, multiple sclerosis, and epilepsy. Despite progress in the drug discovery and development of new drugs, drug delivery to the central nervous system (CNS) still represents the challenge due to the presence of the blood-brain barrier (BBB). Targeting NIF may require an adequate amount of drug to cross the BBB. Recently, the intranasal (IN) drug administration has attracted increasing attention as a reliable method to cross the BBB and treat neurological disorders. On the other hand, using optimized nanoparticles may improve the IN delivery limitations, increase the mucoadhesive properties, and prevent drug degradation. NPs can carry and deliver drugs to the CNS by bypassing the BBB. In this review, we described briefly the NIF as a pathologic feature of CNS diseases. The potential treatment possibilities with IN transfer of NP-loaded drugs will enhance the establishment of more efficient nanoformulations and delivery systems.

Evolution of blood-brain barrier in brain diseases and related systemic nanoscale brain-targeting drug delivery strategies

Blood–brain barrier (BBB) strictly controls matter exchange between blood and brain, and severely limits brain penetration of systemically administered drugs, resulting in ineffective drug therapy of brain diseases. However, during the onset and progression of brain diseases, BBB alterations evolve inevitably. In this review, we focus on nanoscale brain-targeting drug delivery strategies designed based on BBB evolutions and related applications in various brain diseases including Alzheimer's disease, Parkinson's disease, epilepsy, stroke, traumatic brain injury and brain tumor. The advances on optimization of small molecules for BBB crossing and non-systemic administration routes (e.g., intranasal treatment) for BBB bypassing are not included in this review.

Feasibility of implantable iron oxide nanoparticles in detecting brain activity-proof of concept in a rat model

BACKGROUND

Precise detection of zones of increased brain activity is a crucial aspect in the delineation of the cortical region responsible for epilepsy (epileptic focus). When possible, removal of this area can lead to improved control of epilepsy or even its cure. This study explores a new method of detection of electrical brain activity based on the surgical implantation of iron oxide superparamagnetic nanoparticles (SPIONs). By their magnetic nature, SPIONs tend to aggregate in the presence of magnetic fields. This study aims to demonstrate if brain's magnetic fields could change the aggregation status of SPIONs in a rat model.

METHODS

Plastic containers (capsules) containing SPIONs in aqueous suspension were implanted over the cortex of either rats rendered epileptic or naive rats (sham). A model of focal epilepsy using cortical penicillin injection was used for the epileptic rats. Capsules not implanted in rats served as control. Using magnetic resonance imaging (MRI), the aggregation status of SPIONs contained in the capsules was assessed via measurement of the T₂ relaxivity time of the solutions.

RESULTS

Eight Rats were used for the experiments, with 4 rats in each group (epileptic and sham). One Rat in the sham group died immediately after surgery and 3 rats failed to demonstrate the expected behavior after intervention (2 rats in epileptic group with limited observable seizures and 1 rat in the sham group having repeated seizures). T₂ of the control capsules were significantly lower than those implanted in rats (146 ms vs 7.6 ms, p < 0.001), suggesting a higher degree of SPIONs aggregation in the implanted capsules. No significant difference in T₂ could be demonstrated between epileptic and sham rats.

CONCLUSIONS

SPIONs implanted over the cortex of active brain showed an increased aggregation status, confirming their potential as a new marker for brain activity. One of the main advantages of SPIONs is that their aggregation status can be measured at a distance with MRI, taking advantage of its high spatial resolution and imaging capacities. The current model was suboptimal to confirm if epileptic activity can be differentiated from normal brain activity using SPIONs.

Enhanced Antitumor Efficacy of Macrophage-Mediated Egg Yolk Lipid-Derived Delivery System Against Breast Cancer

Background

Chemotherapy is the primary treatment for most cancers apart from surgery. However, the use of chemotherapeutic drugs is limited by side effects and restricted accumulation in tumors because of unique tumor microenvironments. Macrophages have excellent drug delivery potential owing to their chemotaxis and can home in on tumors.

Materials and Methods

We developed an effective drug-delivery system for doxorubicin using macrophages. Doxorubicin-loaded egg yolk lipid-derived nanovectors (EYLNs-Dox) were prepared, EYLNs-Dox-loaded macrophages (Mac/EYLNs-Dox) were developed and their tumor penetration and anti-cancer activity against 4T1 cells were analyzed. The biodistribution and anti-4T1 breast cancer activities were determined using 4T1 subcutaneous and lung metastasis models.

Results

EYLNs-Dox was successfully internalized into macrophages without affecting their viability and was less toxic than Dox. Mac/EYLNs-Dox penetrated the 4T1 tumor spheroids more efficiently and was more effective in inhibiting tumors in vitro. Macrophages significantly enhanced the distribution of EYLNs vectors in both inflammatory and tumor sites, playing a more effective role in the inhibition of tumors.

Conclusion

EYLNs-Dox can be effectively delivered using macrophages and Mac/EYLNs-Dox might be a promising targeted delivery system for breast cancer.

Neuroinflammation Treatment via Targeted Delivery of Nanoparticles

The lack of effective treatments for most neurological diseases has prompted the search for novel therapeutic options. Interestingly, neuroinflammation is emerging as a common feature to target in most CNS pathologies. Recent studies suggest that targeted delivery of small molecules to reduce neuroinflammation can be beneficial. However, suboptimal drug delivery to the CNS is a major barrier to modulate inflammation because neurotherapeutic compounds are currently being delivered systemically without spatial or temporal control. Emerging nanomaterial technologies are providing promising and superior tools to effectively access neuropathological tissue in a controlled manner. Here we highlight recent advances in nanomaterial technologies for drug delivery to the CNS. We propose that state-of-the-art nanoparticle drug delivery platforms can significantly impact local CNS bioavailability of pharmacological compounds and treat neurological diseases.