Central Nervous System Delivery Research Articles

Isolation of Murine Bone Marrow-Derived Neutrophils for Infection Modeling.

West Nile virus (WNV) is a single-stranded-RNA flavivirus that can cause neurological illnesses. The ability of WNV to cause neurological illnesses is dependent on the virus' ability to gain access into the brain. However, the mechanisms by which WNV enters the brain are elusive, with evidence that neutrophils act as vehicles for viral delivery. To determine the role of neutrophils in WNV central nervous system delivery, modified protocols for the isolation and migration of neutrophils from mouse bone marrow for in vitro WNV infection modeling is described.

SPECT/CT imaging reveals CNS-wide modulation of glymphatic cerebrospinal fluid flow by systemic hypertonic saline

SummaryIntrathecal administration enables central nervous system delivery of drugs that do not bypass the blood-brain barrier. Systemic administration of hypertonic saline (HTS) enhances delivery of intrathecal therapeutics into the neuropil, but its effect on solute clearance from the brain remains unknown. Here, we developed a dynamic in vivo single-photon emission computed tomography (SPECT)/computed tomography (CT) imaging platform to study the effects of HTS on whole-body distribution of the radiolabeled tracer 99mTc-diethylenetriaminepentaacetic acid (DTPA) administered through intracisternal, intrastriatal, or intravenous route in anesthetized rats. Co-administration of systemic HTS increased intracranial exposure to intracisternal 99mTc-DTPA by ∼80% during imaging. In contrast, HTS had minimal effects on brain clearance of intrastriatal 99mTc-DTPA. In sum, SPECT/CT imaging presents a valuable approach to study glymphatic drug delivery. Using this methodology, we show that systemic HTS increases intracranial availability of cerebrospinal fluid-administered tracer, but has marginal effects on brain clearance, thus substantiating a simple, yet effective strategy for enhancing intrathecal drug delivery to the brain.

Murine Central Nervous System and Bone Marrow Distribution of the Aurora A Kinase Inhibitor Alisertib: Pharmacokinetics and Exposure at the Sites of Efficacy and Toxicity.

Important challenges in developing drugs that target central nervous system (CNS) tumors include overcoming barriers for CNS delivery and reducing systemic side effects. Alisertib, an aurora A kinase inhibitor, has been examined for treatment of several CNS tumors in preclinical and clinical studies. In this study, we investigated the distribution of alisertib into the CNS, the site of efficacy for brain tumors, and into the bone marrow, the site of dose-limiting toxicity leading to myelosuppression. Mechanisms influencing site-specific distribution, such as active transport mediated by the efflux proteins, p-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp), were examined. Alisertib exposure to the brain in wild-type mice was less than 1% of that in the plasma, and was evenly distributed throughout various brain regions and the spinal cord. Studies using transporter knockout mice and pharmacological inhibition show that alisertib CNS distribution is influenced by P-gp, but not Bcrp. Conversely, upon systemic administration, alisertib distribution to the bone marrow occurred rapidly, was not significantly limited by efflux transporters, and reached higher concentrations than in the CNS. This study demonstrates that, given an equivalent distributional driving force exposure in plasma, the exposure of alisertib in the brain is significantly less than that in the bone marrow, suggesting that targeted delivery may be necessary to guarantee therapeutic efficacy with minimal risk for adverse events.Therefore, these data suggest that, to improve the therapeutic index when using alisertib for brain tumors, a localized regional delivery, such as convection-enhanced delivery, may be warranted. SIGNIFICANCE STATEMENT: The CNS penetration of alisertib is limited with uniform distribution in various regions of the brain, and P-gp efflux is an important mechanism limiting that CNS distribution. Alisertib rapidly distributes into the bone marrow, a site of toxicity, with a greater exposure than in the CNS, a possible site of efficacy. These results suggest a need to design localized delivery strategies to improve the CNS exposure of alisertib and limit systemic toxicities in the treatment of brain tumors.

Application of Nano-based Drug Loading Systems in the Treatment of Neurological Infections: An Updated Review

Infection of the central nervous system (CNS) is a global healthcare concern with high rates of death and disease. CNS infections mainly include meningitis, encephalitis, and brain abscesses. Bacteria, viruses, fungi, protozoa, and parasites are the most common causes of neuroinfections. There are many types of medications used in the treatment of CNS infections, but drug delivery through the blood-brain barrier (BBB) is a major challenge to overcome. The BBB is a specialized multicellular barrier separating the neural tissue from the peripheral blood circulation. Unique characteristics of the BBB allow it to tightly control the movement of ions and molecules. Thus, there is a critical need to deal with these conditions with the aim of improving novel antimicrobial agents. Researchers are still struggling to find effective drugs to treat CNS infections. Nanoparticle (NP)-mediated drug delivery has been considered a profound substitute to solve this problem because NPs can be tailored to facilitate drug transport across the BBB. NPs are colloidal systems with a size range of 1-1000 nm, which can be used to encapsulate therapeutics, improve drug transport across the BBB, and target specific brain areas in CNS infections. A wide variety of NPs has been displayed for the CNS delivery of therapeutics, especially when their surfaces are coated with targeting moieties. This study aimed to review the available literature on the application of NPs in CNS infections.

Abstract LB201: Optimizing adeno-associated viral vector-mediated delivery of trastuzumab to the central nervous system for the treatment of Her2 positive brain metastasis

Abstract Breast cancer is the most common cause of brain metastases in women, affecting 15-30% of all patients. Despite the success of systemic Her2-targeted therapies, up to half of patients with Her2+ primary breast cancer develop breast cancer brain metastases (BCBM). Subtype switching from Her2- primary breast tumors account for an additional 15% of Her2+ BCBM, bringing total Her2 positivity in the BCBM setting to nearly 65% of cases. Even though direct delivery of Her2-targeted therapies to the central nervous system (CNS) has shown promising clinical results, long-term feasibility is limited, at least in part, by the need for repeated dosing to overcome the shorter drug half-life in the cerebrospinal fluid vs. systemic circulation (e.g., ~1 vs. 5 days, respectively). To achieve sustained CNS expression of trastuzumab without frequent dosing, we developed a gene therapy approach to treat BCBM comprising a single local administration of AAV vector encoding trastuzumab. Previous work from our group has shown that intracerebroventricular (ICV) injection of trastuzumab-expressing AAV doubled the life expectancy of Rag1 knockout (KO) mice bearing BT-474 breast cancer brain tumors. Rag1 KO mice who received AAV-trastuzumab prior to implantation of BT-474 tumor cells into the brain showed a dose-dependent delay in tumorigenesis. Following these proof-of-concept studies, we performed extensive gene therapy vector optimization and in vivo evaluation. The concentration of trastuzumab achieved in the brain parenchyma after a single ICV administration of the optimized vectors into Rag1 KO mice ranged from 10-165 ng/mg of brain protein by day 28. Previous studies utilizing CNS delivery of gene therapy vectors have shown vector leakage into the systemic circulation, which results in detectable transgene expression in the blood following peripheral transduction. To mitigate the potential risk of trastuzumab-induced cardiotoxicity, we investigated using intravenously administered, plasma-derived, pooled human immunoglobulin (IVIG) as a source of anti-AAV neutralizing antibodies to reduce peripheral transduction. Compared to controls that received naïve mouse serum, Rag1 KO mice receiving IVIG two hours prior to ICV administration of AAV-trastuzumab exhibited similar levels of trastuzumab within the brain while displaying a 10-fold reduction in serum trastuzumab concentrations. Vector biodistribution analysis suggested that reduced serum trastuzumab levels resulted from effective blockade of liver transduction following IVIG pre-treatment. These data suggest that AAV vector administration to the CNS to achieve sustained expression of trastuzumab may effectively treat Her2+ BCBM. Additionally, patients with pre-existing neutralizing antibodies to the AAV vector capsid need not be excluded from future clinical trials. Citation Format: Marcela Salazar Werner, Shweta Aras, Ashleigh Morgan, Nesteene J. Param, Jenny Greig, James M. Wilson. Optimizing adeno-associated viral vector-mediated delivery of trastuzumab to the central nervous system for the treatment of Her2 positive brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB201.

New Drug Delivery Systems Developed for Brain Targeting.

The blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSF) are two of the most complex and sophisticated concierges that defend the central nervous system (CNS) by numerous mechanisms. While they maintain the neuro-ecological homeostasis through the regulated entry of essential biomolecules, their conservative nature challenges the entry of most of the drugs intended for CNS delivery. Targeted delivery challenges for a diverse spectrum of therapeutic agents/drugs (non-small molecules, small molecules, gene-based therapeutics, protein and peptides, antibodies) are diverse and demand specialized delivery and disease-targeting strategies. This review aims to capture the trends that have shaped the current brain targeting research scenario. This review discusses the physiological, neuropharmacological, and etiological factors that participate in the transportation of various drug delivery cargoes across the BBB/BCSF and influence their therapeutic intracranial concentrations. Recent research works spanning various invasive, minimally invasive, and non-invasive brain- targeting approaches are discussed. While the pre-clinical outcomes from many of these approaches seem promising, further research is warranted to overcome the translational glitches that prevent their clinical use. Non-invasive approaches like intranasal administration, P-glycoprotein (P-gp) inhibition, pro-drugs, and carrier/targeted nanocarrier-aided delivery systems (alone or often in combination) hold positive clinical prospects for brain targeting if explored further in the right direction.

Central and peripheral delivered AAV9-SMN are both efficient but target different pathomechanisms in a mouse model of spinal muscular atrophy.

Spinal muscular atrophy (SMA) is a neuromuscular disease caused by loss of the SMN1 gene and low SMN protein levels. Although lower motor neurons are a primary target, there is evidence that peripheral organ defects contribute to SMA. Current SMA gene therapy and clinical trials use a single intravenous bolus of the blood-brain-barrier penetrant scAAV9-cba-SMN by either systemic or central nervous system (CNS) delivery, resulting in impressive amelioration of the clinical phenotype but not a complete cure. The impact of scAAV9-cba-SMN treatment regimens on the CNS as well as on specific peripheral organs is yet to be described in a comparative manner. Therefore, we injected SMA mice with scAAV9-cba-SMN either intravenously (IV) for peripheral SMN restoration or intracerebroventricularly (ICV) for CNS-focused SMN restoration. In our system, ICV injections increased SMN in peripheral organs and the CNS while IV administration increased SMN in peripheral tissues only, largely omitting the CNS. Both treatments rescued several peripheral phenotypes while only ICV injections were neuroprotective. Surprisingly, both delivery routes resulted in a robust rescue effect on survival, weight, and motor function, which in IV-treated mice relied on peripheral SMN restoration but not on targeting the motor neurons. This demonstrates the independent contribution of peripheral organs to SMA pathology and suggests that treatments should not be restricted to motor neurons.

Central Nervous System Delivery of the Catalytic Subunit of DNA-Dependent Protein Kinase Inhibitor Peposertib as Radiosensitizer for Brain Metastases.

Cytotoxic effects of chemotherapy and radiation therapy (RT) used for the treatment of brain metastases results from DNA damage within cancer cells. Cells rely on highly evolved DNA damage response (DDR) pathways to repair the damage caused by these treatments. Inhibiting these repair pathways can further sensitize cancer cells to chemotherapy and RT. The catalytic subunit of DNA-dependent protein kinase, in a complex with Ku80 and Ku70, is a pivotal regulator of the DDR, and peposertib is a potent inhibitor of this catalytic subunit. The characterization of central nervous system (CNS) distributional kinetics of peposertib is critical in establishing a therapeutic index in the setting of brain metastases. Our studies demonstrate that the delivery of peposertib is severely restricted into the CNS as opposed to peripheral organs, by active efflux at the blood-brain barrier (BBB). Peposertib has a low free fraction in the brain and spinal cord, further reducing the active concentration, and distributes to the same degree within different anatomic regions of the brain. However, peposertib is heterogeneously distributed within the metastatic tumor, where its concentration is highest within the tumor core (with disrupted BBB) and substantially lower within the invasive tumor rim (with a relatively intact BBB) and surrounding normal brain. These findings are critical in guiding the potential clinical deployment of peposertib as a radiosensitizing agent for the safe and effective treatment of brain metastases. SIGNIFICANCE STATEMENT: Effective radiosensitization of brain metastases while avoiding toxicity to the surrounding brain is critical in the development of novel radiosensitizers. The central nervous system distribution of peposertib, a potent catalytic subunit of DNA-dependent protein kinase inhibitor, is restricted by active efflux in the normal blood-brain barrier (BBB) but can reach significant concentrations in the tumor core. This finding suggests that peposertib may be an effective radiosensitizer for intracranial tumors with an open BBB, while limited distribution into normal brain will decrease the risk of enhanced radiation injury.

Strategies for Targeted Delivery of Exosomes to the Brain: Advantages and Challenges.

Delivering therapeutics to the central nervous system (CNS) is difficult because of the blood–brain barrier (BBB). Therapeutic delivery across the tight junctions of the BBB can be achieved through various endogenous transportation mechanisms. Receptor-mediated transcytosis (RMT) is one of the most widely investigated and used methods. Drugs can hijack RMT by expressing specific ligands that bind to receptors mediating transcytosis, such as the transferrin receptor (TfR), low-density lipoprotein receptor (LDLR), and insulin receptor (INSR). Cell-penetrating peptides and viral components originating from neurotropic viruses can also be utilized for the efficient BBB crossing of therapeutics. Exosomes, or small extracellular vesicles, have gained attention as natural nanoparticles for treating CNS diseases, owing to their potential for natural BBB crossing and broad surface engineering capability. RMT-mediated transport of exosomes expressing ligands such as LDLR-targeting apolipoprotein B has shown promising results. Although surface-modified exosomes possessing brain targetability have shown enhanced CNS delivery in preclinical studies, the successful development of clinically approved exosome therapeutics for CNS diseases requires the establishment of quantitative and qualitative methods for monitoring exosomal delivery to the brain parenchyma in vivo as well as elucidation of the mechanisms underlying the BBB crossing of surface-modified exosomes.

An orally available, brain penetrant, small molecule lowers huntingtin levels by enhancing pseudoexon inclusion

Huntington’s Disease (HD) is a progressive neurodegenerative disorder caused by CAG trinucleotide repeat expansions in exon 1 of the huntingtin (HTT) gene. The mutant HTT (mHTT) protein causes neuronal dysfunction, causing progressive motor, cognitive and behavioral abnormalities. Current treatments for HD only alleviate symptoms, but cerebral spinal fluid (CSF) or central nervous system (CNS) delivery of antisense oligonucleotides (ASOs) or virus vectors expressing RNA-induced silencing (RNAi) moieties designed to induce mHTT mRNA lowering have progressed to clinical trials. Here, we present an alternative disease modifying therapy the orally available, brain penetrant small molecule branaplam. By promoting inclusion of a pseudoexon in the primary transcript, branaplam lowers mHTT protein levels in HD patient cells, in an HD mouse model and in blood samples from Spinal Muscular Atrophy (SMA) Type I patients dosed orally for SMA (NCT02268552). Our work paves the way for evaluating branaplam’s utility as an HD therapy, leveraging small molecule splicing modulators to reduce expression of dominant disease genes by driving pseudoexon inclusion.

Understanding the Blood-Brain Barrier and Beyond: Challenges and Opportunities for Novel CNS Therapeutics.

This review addresses questions on how to accomplish successful central nervous system (CNS) drug delivery (i.e., having the right concentration at the right CNS site, at the right time), by understanding the rate and extent of blood‐brain barrier (BBB) transport and intra‐CNS distribution in relation to CNS target site(s) exposure. To this end, we need to obtain and integrate quantitative and connected data on BBB using the Combinatory Mapping Approach that includes in vivo and ex vivo animal measurements, and the physiologically based comprehensive LEICNSPK3.0 mathematical model that can translate from animals to humans. For small molecules, slow diffusional BBB transport and active influx and efflux BBB transport determine the differences between plasma and CNS pharmacokinetics. Obviously, active efflux is important for limiting CNS drug delivery. Furthermore, liposomal formulations of small molecules may to a certain extent circumvent active influx and efflux at the BBB. Interestingly, for CNS pathologies, despite all reported disease associated BBB and CNS functional changes in animals and humans, integrative studies typically show a lack of changes on CNS drug delivery for the small molecules. In contrast, the understanding of the complex vesicle‐based BBB transport modes that are important for CNS delivery of large molecules is in progress, and their BBB transport seems to be significantly affected by CNS diseases. In conclusion, today, CNS drug delivery of small drugs can be well assessed and understood by integrative approaches, although there is still quite a long way to go to understand CNS drug delivery of large molecules.

Establishment of an Olfactory Region-specific Intranasal Delivery Technique in Mice to Target the Central Nervous System.

We have recently developed a region-specific catheter-based intranasal application method in mice by using CT scan-based 3D cast models of the murine nose (DOI: 10.2376/0005-9366-17,102). This technique is able to specifically deliver drugs to the olfactory region or to the respiratory region only. Thereby, intranasally administered drugs could be delivered either via neuronal connections to the central nervous system or via the well-perfused rostral parts of the nasal mucosa to the systemic circulation. In the present study, we transferred successfully this novel delivery technique to C57Bl/6 mice and determined parameters such as insertions depth of the catheter and maximum delivery volume in dependence to the weight of the mouse. Breathing was simulated to verify that the volume remains at the targeted area. A step-by-step procedure including a video is presented to adopt this technique for standardized and reproducible intranasal central nervous system (CNS) delivery studies (DOI : 10.3390/ pharmaceutics13111904).

In Vitro Models of the Blood-Brain Barrier.

Traditional in vitro models can replicate many essential features of drug transport/permeability across the blood-brain barrier (BBB) but are not entirely projecting in vivo central nervous system (CNS) uptake. Species differences fail to translate experimental therapeutics from the research laboratory to the clinic. Improved in vitro modeling of human BBB is vital for both CNS drug discovery and delivery. High-end human BBB models fabricated by microfluidic technologies offer some solutions to this problem. BBB's complex physiological microenvironment has been established by increasing device complexity in terms of multiple cells, dynamic conditions, and 3D designs. It is now possible to predict the therapeutic effects of a candidate drug and identify new druggable targets by studying multicellular interactions using the advanced in vitro BBB models. This chapter reviews the current as well as an ideal in vitro model of the BBB.

Central Nervous System Delivery of Antibodies and Their Single-Domain Antibodies and Variable Fragment Derivatives with Focus on Intranasal Nose to Brain Administration.

IgG antibodies are some of the most important biopharmaceutical molecules with a high market volume. In spite of the fact that clinical therapies with antibodies are broadly utilized in oncology, immunology and hematology, their delivery strategies and biodistribution need improvement, their limitations being due to their size and poor ability to penetrate into tissues. In view of their small size, there is a rising interest in derivatives, such as single-domain antibodies and single-chain variable fragments, for clinical diagnostic but also therapeutic applications. Smaller antibody formats combine several benefits for clinical applications and can be manufactured at reduced production costs compared with full-length IgGs. Moreover, such formats have a relevant potential for targeted drug delivery that directs drug cargo to a specific tissue or across the blood–brain barrier. In this review, we give an overview of the challenges for antibody drug delivery in general and focus on intranasal delivery to the central nervous system with antibody formats of different sizes.

Role of Laser Interstitial Thermal Therapy in the Management of Primary and Metastatic Brain Tumors.

Laser interstitial thermal therapy (LITT) is a minimally invasive treatment option for brain tumors including glioblastoma, other primary central nervous system (CNS) neoplasms, metastases, and radiation necrosis. LITT employs a fiber optic coupled laser delivery probe stabilized via stereotaxis to deliver thermal energy that induces coagulative necrosis in tumors to achieve effective cytoreduction. LITT complements surgical resection, radiation treatment, tumor treating fields, and systemic therapy, especially in patients who are high risk for surgical resection due to tumor location in eloquent regions or poor functional status. These factors must be balanced with the increased rate of cerebral edema post LITT compared to surgical resection. LITT has also been shown to induce transient disruption of the blood-brain barrier (BBB), especially in the peritumoral region, which allows for enhanced CNS delivery of anti-neoplastic agents, thus greatly expanding the armamentarium against brain tumors to include highly effective anti-neoplastic agents that have poor BBB penetration. In addition, hyperthermia-induced immunogenic cell death is another secondary side effect of LITT that opens up immunotherapy as an attractive adjuvant treatment for brain tumors. Numerous large studies have demonstrated the safety and efficacy of LITT against various CNS tumors and as the literature continues to grow on this novel technique so will its indications.

Osmotic core-shell polymeric implant for sustained BDNF AntagoNAT delivery in CNS using minimally invasive nasal depot (MIND) approach

The development of drug delivery strategies for efficacious therapeutic administration directly into the central nervous system (CNS) in a minimally invasive manner remains a major obstacle hindering the clinical translation of biological disease-modifying therapeutics. A novel direct trans-nasal delivery method, termed ‘Minimally-Invasive Nasal Depot’ (MIND), has proved to be successful in providing high CNS uptake and brain distribution of blood-brain barrier (BBB) impermeant therapeutics via direct administration to the olfactory submucosal space in a rodent model. The present study describes the engineering of custom-made implants with a unique architecture of an “osmotically-active core” entrapping the therapeutic and a “biodegradable polymeric shell” to enable long-acting delivery using the MIND procedure. The MIND-administered implant provided sustained CNS delivery of brain derived neurotrophic factor (BDNF) AntagoNATs for up to 4 weeks in Sprague Dawley rats resulting in significant endogenous BDNF protein upregulation in several brain tissues. The biocompatibility of such core-shell implants coupled with their substantial pharmacokinetic advantages and safety of the MIND procedure highlights the practical utility and translational potential of this synergistic approach for treatment of chronic age-related neurodegenerative diseases.

Self-buffering capacity of a human sulfatase for central nervous system delivery

Direct delivery of therapeutic enzymes to the Central Nervous System requires stringent formulation design. Not only should the formulation design consider the delicate balance of existing ions, proteins, and osmolality in the cerebrospinal fluid, it must also provide long term efficacy and stability for the enzyme. One fundamental approach to this predicament is designing formulations with no buffering species. In this study, we report a high concentration, saline-based formulation for a human sulfatase for its delivery into the intrathecal space. A high concentration formulation (≤ 40 mg/mL) was developed through a series of systematic studies that demonstrated the feasibility of a self-buffered formulation for this molecule. The self-buffering capacity phenomenon was found to be a product of both the protein itself and potentially the residual phosphates associated with the protein. To date, the self-buffered formulation for this molecule has been stable for up to 4 years when stored at 5 ± 3 °C, with no changes either in the pH values or other quality attributes of the molecule. The high concentration self-buffered protein formulation was also observed to be stable when exposed to multiple freeze–thaw cycles and was robust during in-use and agitation studies.

Advances in the Design of (Nano)Formulations for Delivery of Antisense Oligonucleotides and Small Interfering RNA: Focus on the Central Nervous System.

RNA-based therapeutics have emerged as one of the most powerful therapeutic options used for the modulation of gene/protein expression and gene editing with the potential to treat neurodegenerative diseases. However, the delivery of nucleic acids to the central nervous system (CNS), in particular by the systemic route, remains a major hurdle. This review will focus on the strategies for systemic delivery of therapeutic nucleic acids designed to overcome these barriers. Pathways and mechanisms of transport across the blood–brain barrier which could be exploited for delivery are described, focusing in particular on smaller nucleic acids including antisense oligonucleotides (ASOs) and small interfering RNA (siRNA). Approaches used to enhance delivery including chemical modifications, nanocarrier systems, and target selection (cell-specific delivery) are critically analyzed. Learnings achieved from a comparison of the successes and failures reported for CNS delivery of ASOs versus siRNA will help identify opportunities for a wider range of nucleic acids and accelerate the clinical translation of these innovative therapies.

Endosomal escape cell-penetrating peptides significantly enhance pharmacological effectiveness and CNS activity of systemically administered antisense oligonucleotides

Antisense oligonucleotides (ASOs) are an emerging class of gene-specific therapeutics for diseases associated with the central nervous system (CNS). However, ASO delivery across the blood–brain barrier (BBB) to their CNS target cells remains a major challenge. Since ASOs are mainly taken up into the brain capillary endothelial cells interface through endosomal routes, entrapment in the endosomal compartment is a major obstacle for efficient CNS delivery of ASOs. Therefore, we evaluated the effectiveness of a panel of cell-penetrating peptides (CPPs) bearing several endosomal escape domains for the intracellular delivery, endosomal release and antisense activity of FDA-approved Spinraza (Nusinersen), an ASO used to treat spinal muscular atrophy (SMA). We identified a CPP, HA2-ApoE(131–150), which, when conjugated to Nusinersen, showed efficient endosomal escape capability and significantly increased the level of full-length functional mRNA of the survival motor neuron 2 (SMN2) gene in SMA patient-derived fibroblasts. Treatment of SMN2 transgenic adult mice with this CPP-PMO conjugate resulted in a significant increase in the level of full-length SMN2 in the brain and spinal cord. This work provides proof-of-principle that integration of endosomal escape domains with CPPs enables higher cytosolic delivery of ASOs, and more importantly enhances the efficiency of BBB-permeability and CNS activity of systemically administered ASOs.

Aptamer and RVG functionalized gold nanorods for targeted photothermal therapy of neurotropic virus infection in the mouse brain

The infection of the neurotropic virus damages the central nervous system (CNS) and often leads to humans' fatal symptoms. Rabies is a lethal disease caused by a typical neurotropic virus, rabies virus (RABV). To date, there is no effective clinical therapy for rabies. In this report, an aptamer conjugated RVG-Apt-PEG-Silica gold nanorods (AuNR)-based photothermal therapy (PTT) was developed and evaluated in a mouse model. The DNA aptamer was conjugated on the nanoparticle to provide specificity for targeting RABV glycoprotein in cells and mouse brains. A 29-aa rabies virus glycopeptide (RVG) was conjugated on the nanoparticle to enhance CNS delivery. The virions were inactivated in cell supernatant, and an approximately 100-fold decrease of viral load was observed in cells 5 min post-PTT. This AuNR did not cause distinct apoptosis, inflammation, or pathological lesion in the mouse brains post PTT. At 3 day post-infection, significantly enhanced survival ratio (60%) was observed in mice received PTT compared with the mice without PTT. In the PTT group, both the viral RNA level and the distribution of RABV in mouse brains were significantly decreased. Collectively, aptamer conjugated RVG-Apt-PEG-Silica AuNR-based PTT could be considered as a promising strategy for clinical treatment with neurotropic virus infection.