Advancements in drug delivery methods for the treatment of brain disease

Designing a time-dependent therapeutic strategy using CDK4/6 inhibitors in an intracranial ATRT model

BACKGROUND

Inhibitors targeting cyclin-dependent kinases 4 and 6 (CDK4/6), crucial for cell cycle regulation, have shown promise in early-stage studies for treating central nervous system (CNS) tumors. However, challenges such as limited CNS penetration, optimal treatment duration, and systemic side effects have impeded their clinical translation for pediatric brain tumors (PBTs).

METHODS

We evaluated the potency of CDK4/6 inhibitors across various PBT cell lines, focusing particularly on palbociclib against atypical teratoid rhabdoid tumor (ATRT) with cell viability assays and gene expression analysis. Additionally, we assessed the efficacy and safety of intrathecal (IT) delivery of palbociclib through neurotoxicity and pharmacokinetic studies, along with survival assessments in murine leptomeningeal ATRT models.

RESULTS

Palbociclib showed the highest potency across various PBT cells, with extended treatments reducing growth inhibition 50 (GI50) values from the micromolar to nanomolar range. It suppressed critical cell cycle genes (CCNB1, CCNA2, CDK1) in BT16 ATRT cells. Neurotoxicity (GFAP, CD45, NeuN, Iba1) and pharmacokinetic assays confirmed IT route as a feasible and effective method for delivering palbociclib to the cerebrospinal fluid (CSF), avoiding systemic toxicity and enhancing drug concentration to the brain. Finally, metronomic IT delivery using an osmotic pump (OP, 48 mg/kg) increased survival in 2 murine leptomeningeal ATRT models, showcasing its potential as a novel therapy for leptomeningeal tumors.

CONCLUSIONS

Metronomic IT delivery of palbociclib enhances drug efficacy and safety, improves survival, and offers a promising treatment strategy for PBTs with CSF dissemination.

Platelet Extracellular Vesicles as Natural Delivery Vehicles for Mitochondrial Dysfunction Therapy?

Mitochondria are vital for energy production, metabolic regulation, and cellular signaling. Their dysfunction is strongly implicated in neurological, cardiovascular, and muscular degenerative diseases, where energy deficits and oxidative stress accelerate disease progression. Platelet extracellular vesicles (PEVs), once called "platelet dust", have emerged as promising agents for mitigating mitochondrial dysfunction. Like other extracellular vesicles (EVs), PEVs carry diverse molecular cargo and surface markers implicated in disease processes and therapeutic efficacy. Notably, they may possibly contain intact or partially functional mitochondrial components, making them tentatively attractive for targeting mitochondrial damage. Although direct research on PEVs-mediated mitochondrial rescue remains limited, current evidence suggests that PEVs can modulate diseases associated with mitochondrial dysfunction and potentially enhance mitochondrial health. This review explores the therapeutic potential of PEVs in neurodegenerative and cardiovascular disorders, highlighting their role in restoring mitochondrial health. By examining recent advancements in PEVs research, we aim to shed light on novel strategies for utilizing PEVs as therapeutic agents. Our goal is to underscore the importance of further fundamental and applied research into PEVs-based interventions, as innovative tools for combating a wide range of diseases linked to mitochondrial dysfunction.

Utilization of nanotechnology to surmount the blood-brain barrier in disorders of the central nervous system

Central nervous system (CNS) diseases are a major cause of disability and death worldwide. Due to the blood-brain barrier (BBB), drug delivery for CNS diseases is extremely challenging. Nano-delivery systems can overcome the limitations of BBB to deliver drugs to the CNS, improve the ability of drugs to target the brain and provide potential therapeutic methods for CNS diseases. At the same time, the choice of different drug delivery methods (bypassing BBB or crossing BBB) can further optimize the therapeutic effect of the nano-drug delivery system. This article reviews the different methods of nano-delivery systems to overcome the way BBB enters the brain. Different kinds of nanoparticles to overcome BBB were discussed in depth.

Advancing neurological disorders therapies: Organic nanoparticles as a key to blood-brain barrier penetration

The blood-brain barrier (BBB) plays a vital role in protecting the central nervous system (CNS) by preventing the entry of harmful pathogens from the bloodstream. However, this barrier also presents a significant obstacle when it comes to delivering drugs for the treatment of neurodegenerative diseases and brain cancer. Recent breakthroughs in nanotechnology have paved the way for the creation of a wide range of nanoparticles (NPs) that can serve as carriers for diagnosis and therapy. Regarding their promising properties, organic NPs have the potential to be used as effective carriers for drug delivery across the BBB based on recent advancements. These remarkable NPs have the ability to penetrate the BBB using various mechanisms. This review offers a comprehensive examination of the intricate structure and distinct properties of the BBB, emphasizing its crucial function in preserving brain balance and regulating the transport of ions and molecules. The disruption of the BBB in conditions such as stroke, Alzheimer's disease, and Parkinson's disease highlights the importance of developing creative approaches for delivering drugs. Through the encapsulation of therapeutic molecules and the precise targeting of transport processes in the brain vasculature, organic NP formulations present a hopeful strategy to improve drug transport across the BBB. We explore the changes in properties of the BBB in various pathological conditions and investigate the factors that affect the successful delivery of organic NPs into the brain. In addition, we explore the most promising delivery systems associated with NPs that have shown positive results in treating neurodegenerative and ischemic disorders. This review opens up new possibilities for nanotechnology-based therapies in cerebral diseases.

Targeted drug delivery in neurodegenerative diseases: the role of nanotechnology

Neurodegenerative diseases, characterized by progressive neuronal loss and cognitive impairments, pose a significant global health challenge. This study explores the potential of nanotherapeutics as a promising approach to enhance drug delivery across physiological barriers, particularly the blood-brain barrier (BBB) and blood-cerebrospinal fluid barrier (B-CSFB). By employing nanoparticles, this research aims to address critical challenges in the diagnosis and treatment of conditions such as Alzheimer's, Parkinson's, and Huntington's diseases. The multifactorial nature of these disorders necessitates innovative solutions that leverage nanomedicine to improve drug solubility, circulation time, and targeted delivery while minimizing off-target effects. The findings underscore the importance of advancing nanomedicine applications to develop effective therapeutic strategies that can alleviate the burden of neurodegenerative diseases on individuals and healthcare systems.

Mesenchymal stem cells as a therapeutic strategy to combat oxidative stress-mediated neuropathic pain

Neuropathic pain, a chronic condition resulting from somatosensory system damage, remains a significant clinical challenge due to its complex pathophysiology and inadequate response to traditional therapies. Oxidative stress, characterized by an imbalance between free radicals production and antioxidant defenses, plays a pivotal role in the development and maintenance of neuropathic pain. Mesenchymal stem cells (MSCs) are multipotent stromal cells with the ability to differentiate into various cell types and possess immunomodulatory, anti-inflammatory, and regenerative properties, making them promising candidates for novel pain management strategies. Preclinical studies demonstrate that MSCs can reduce inflammation, scavenge reactive oxygen species (ROS), promote nerve regeneration, and modulate pain signaling pathways. Various administration routes, including intravenous and intrathecal, have been investigated to optimize MSC delivery and efficacy. Additionally, MSC-derived extracellular vesicles (EVs) represent a cell-free alternative with substantial therapeutic potential. Despite encouraging preclinical findings, further research is needed to refine MSC-based therapies, including the exploration of combination treatments and rigorous clinical trials, to translate these promising results into effective clinical applications for neuropathic pain relief. This review explores the therapeutic potential of MSCs in alleviating oxidative stress-mediated neuropathic pain.

Revolutionizing Stroke Care: Nanotechnology-Based Brain Delivery as a Novel Paradigm for Treatment and Diagnosis

Stroke, a severe medical condition arising from abnormalities in the coagulation-fibrinolysis cycle and metabolic processes, results in brain cell impairment and injury due to blood flow obstruction within the brain. Prompt and efficient therapeutic approaches are imperative to control and preserve brain functions. Conventional stroke medications, including fibrinolytic agents, play a crucial role in facilitating reperfusion to the ischemic brain. However, their clinical efficacy is hampered by short plasma half-lives, limited brain tissue distribution attributed to the blood-brain barrier (BBB), and lack of targeted drug delivery to the ischemic region. To address these challenges, diverse nanomedicine strategies, such as vesicular systems, polymeric nanoparticles, dendrimers, exosomes, inorganic nanoparticles, and biomimetic nanoparticles, have emerged. These platforms enhance drug pharmacokinetics by facilitating targeted drug accumulation at the ischemic site. By leveraging nanocarriers, engineered drug delivery systems hold the potential to overcome challenges associated with conventional stroke medications. This comprehensive review explores the pathophysiological mechanism underlying stroke and BBB disruption in stroke. Additionally, this review investigates the utilization of nanocarriers for current therapeutic and diagnostic interventions in stroke management. By addressing these aspects, the review aims to provide insight into potential strategies for improving stroke treatment and diagnosis through a nanomedicine approach.

Novel Treatments for Brain Tumors

The blood-brain barrier and knowledge gaps in tumor biology remain significant obstacles to the development of effective treatments for brain tumors. The identification of shared molecular and genetic pathways that contribute to tumorigenesis in both dogs and people has been key to the discovery and translation of targeted pharmacologic and biologic therapies. Treatment approaches often utilize targeted or multifunctional antitumor agents, such as nanocarriers, molecularly targeted agents, immunotherapeutics, and oncolytic viruses in combination with alternative therapeutic delivery strategies. The article discusses about various treatments albeit none of the treatments discussed here are widely available or approved for clinical use.

Potential of Nanoparticle based Antimicrobial Drug Repurposing to Efficiently Target Alzheimer's: A Concise Update on Evidence-based Research and Challenges Ahead

Repurposing of drugs through nanocarriers (NCs) based platforms has been a recent trend in drug delivery research. Various routine drugs are now being repurposed to treat challenging neurodegenerative disorders including Alzheimer disease (AD). AD, at present is one of the challenging neurodegenerative disorders characterized by extracellular accumulation of amyloid-β and intracellular accumulations of neurofibrillary tangles. In spite of catchy progress in drug development, effective treatment outcome in AD patients is far-fetched dream. Out of several proposed hypothesis in the development and progression of AD, potential role of microorganisms causing dementia and AD cannot be ruled out. Several recent researches have been documented a clear correlation in between microbial infection and neuronal damage leading to progression of AD. Thus, antimicrobial drugs repurposing has been emerged as alternate, potential, cost-effective strategy to check progression of AD. Further, for efficient delivery of antimicrobial drugs to brain tissue, novel NCs based platforms are the preferred option to bypass blood-brain barrier. Several polymeric and lipid NCs have been extensively studied over the past years to improve antimicrobial drug delivery to brain. The present review encompasses various repurposing strategy of antimicrobial drugs delivered through various NCs to target AD. Evidence-based research outcome compiled from authentic database like Scopus, PubMed, Web of science have been pooled to provide an updated review. Side by side some light has been thrown on the practical problems faced by nanodrug carriers during technology transfer.

Modulating membrane-bound enzyme activity with chemical stimuli

Membrane-bound enzymes play pivotal roles in various cellular processes, making their activity regulation essential for cellular homeostasis and signaling transduction. Given that dysregulation of membrane-bound enzymes involved in various disease, controlling enzyme activity offers valuable avenues for designing targeted therapies and novel pharmaceutical interventions. This review explores chemical stimuli-responsive strategies for modulating the activity of these enzymes, employing diverse stimuli such as small molecules, proteins, nucleic acids, and bifunctional molecules to either inhibit or enhance their catalytic function. We systematically delineate the mechanisms underlying enzyme activity regulation, including substrate binding site blockade, conformational changes, and local concentration of enzymes and substrates. Furthermore, based on some examples, we elucidate the binding modalities between stimuli and enzymes, along with potential modes of regulation, and discuss their potential medical applications and future prospects. This review underscores the significance of understanding and manipulating enzyme activity on the cell membrane for advancing biomedical research and therapeutic development.

Current Combinatorial Therapeutic Aspects: The Future Prospect for Glioblastoma Treatment

There are several types of brain tumors but glioblastoma (GBM) is one of the highly malignant tumors. A primary concern with GBM is that the treatment is inadequate. Even after giving many multi-stacked combinations of therapies to patients, inclusive of chemotherapy, radiation, and surgery, the median survival rate remains poor. Due to its heterogeneous nature, the use of selective therapy for specific targeting of tumor cells is of particular importance. Although many treatment alternatives which include surgery with adjuvant chemotherapy and radiotherapy are available, the prognosis of the disease is very poor. Combination therapy is becoming the foundation of modern antitumor therapy and it is continuously evolving and developing innovative drug regimens as evidenced by ongoing preclinical and clinical trials. In this review, we discuss the current treatment options and emerging therapeutic approaches for the treatment of GBM. The prospects for alternative glioblastoma therapy are also discussed.

Hydrocephalus: An update on latest progress in pathophysiological and therapeutic research

Hydrocephalus is a severe and life-threatening disease associated with the imbalance of CSF dynamics and affects millions globally at any age, including infants. One cause of pathology that is wide-ranging is genetic mutations to post-traumatic injury. The most effective current pharmacological treatments provide only symptomatic relief and do not address the underlying pathology. At the same time, surgical procedures such as VP shunts performed in lower-income countries are often poorly tolerated due to insufficient diagnostic resources and suboptimal outcomes partially attributable to inferior materials. These problems are compounded by an overall lack of funding that keeps high-quality medical devices out of reach for all but the most developed countries and even among those states. There is a massive variance in treatment effectiveness. This review indicates the necessity for innovative and low-cost, accessible treatment strategies to close these gaps, focusing on current advances in novel therapies, including Pharmacological, gene therapy, and nano-based technologies, which are currently at different stages of clinical trial phases. This review provides an overview of pathophysiology, current treatments, and promising new therapeutic strategies for hydrocephalus.

Small molecule inhibitors target multiple neuropathological signaling to exert novel neuroprotection in intracranial aneurysms

Intracranial aneurysms (IAs) represent a critical health concern due to their potential to rupture, leading to severe morbidity and mortality. Small molecule inhibitors (SMIs) have emerged as promising therapeutic candidates for managing IA progression and rupture risk. The current landscape of SMIs targets various molecular pathways implicated in IA pathogenesis, including inflammation, endothelial dysfunction, and extracellular matrix (ECM) degradation. Among the prominent therapeutic candidates discussed are statins, recognized for their multifaceted effects, anti-inflammatory properties, and enhancement of endothelial stability, which may mitigate IA progression. Matrix metalloproteinase inhibitors are also highlighted for their role in preserving ECM structural integrity, essential for preventing IA wall weakening and rupture. Furthermore, the review evaluates the efficacy of anti-inflammatory agents such as corticosteroids and cytokine inhibitors in attenuating IA growth driven by inflammatory processes. Our findings highlight the possibility of several pharmaceutical therapies that target matrix remodeling, inflammation, and other underlying processes to manage cerebral aneurysms. By precisely delivering therapeutic chemicals, such as antioxidants, gene therapy vectors, or anti-inflammatory medicines, to the aneurysm site, these SMI technologies treat the underlying pathophysiological causes while sparing healthy brain tissue. This review underscores the potential of SMIs as adjunctive or primary therapies in the comprehensive management of IAs, emphasizing the need for further clinical research to optimize their efficacy and safety in clinical practice.

A Scoping Review of Focused Ultrasound Enhanced Drug Delivery for Across the Blood-Brain Barrier for Brain Tumors

BACKGROUND AND OBJECTIVES

Previous mechanisms of opening the blood-brain barrier (BBB) created a hypertonic environment. Focused ultrasound (FUS) has recently been introduced as a means of controlled BBB opening. Here, we performed a scoping review to assess the advances in drug delivery across the BBB for treatment of brain tumors to identify advances and literature gaps.

METHODS

A review of current literature was conducted through a MEDLINE search inclusive of articles on FUS, BBB, and brain tumor barrier, including human, modeling, and animal studies written in English. Using the Rayyan platform, 2 reviewers (J.P and C.Y) identified 967 publications. 224 were chosen to review after a title screen. Ultimately 98 were reviewed. The scoping review was designed to address the following questions: (1) What FUS technology improvements have been made to augment drug delivery for brain tumors? (2) What drug delivery improvements have occurred to ensure better uptake in the target tissue for brain tumors?

RESULTS

Microbubbles (MB) with FUS are used for BBB opening (BBBO) through cavitation to increase its permeability. Drug delivery into the central nervous system can be combined with MB to enhance transport of therapeutic agents to target brain tissue resulting in suppression of tumor growth and prolonging survival rate, as well as reducing systemic toxicity and degradation rate. There is accumulating evidence demonstrating that drug delivery through BBBO with FUS-MB improves drug concentrations and provides a better impact on tumor growth and survival rates, compared with drug-only treatments.

CONCLUSION

Here, we review the role of FUS in BBBO. Identified gaps in the literature include impact of tumor microenvironment and extracellular space, improved understanding and control of MB and drug delivery, further work on ideal pharmacologics for delivery, and clinical use.

Navigating Neurotoxicity and Safety Assessment of Nanocarriers for Brain Delivery: Strategies and Insights

Nanomedicine, an area that uses nanomaterials for theragnostic purposes, is advancing rapidly, particularly in the detection and treatment of neurodegenerative diseases. The design of nanocarriers can be optimized to enhance drug bioavailability and targeting to specific organs, improving therapeutic outcomes. However, clinical translation hinges on biocompatibility and safety. Nanocarriers can cross the blood-brain barrier (BBB), potentially causing neurotoxic effects through mechanisms such as oxidative stress, DNA damage, and neuroinflammation. Concerns about their accumulation and persistence in the brain make it imperative to carry out a nanotoxicological risk assessment. Generally, this involves identifying exposure sources and routes, characterizing physicochemical properties, and conducting cytotoxicity assays both in vitro and in vivo. The lack of a specialized regulatory framework creates substantial gaps, making it challenging to translate findings across development stages. Additionally, there is a pressing need for innovative testing methods due to constraints on animal use and the demand for high-throughput screening. This review examines the mechanisms of nanocarrier-induced neurotoxicity and the challenges in risk assessment, highlighting the impact of physicochemical properties and the advantages and limitations of current neurotoxicity evaluation models. Future perspectives are also discussed. Additional guidance is crucial to improve the safety of nanomaterials and reduce associated uncertainty. STATEMENT OF SIGNIFICANCE: Nanocarriers show tremendous potential for theragnostic purposes in neurological diseases, enhancing drug targeting to the brain, and improving biodistribution and pharmacokinetics. However, their neurotoxicity is still a major field to be explored, with only 5% of nanotechnology-related publications addressing this matter. This review focuses on the issue of neurotoxicity and safety assessment of nanocarriers for brain delivery. Neurotoxicity-relevant exposure sources, routes, and molecular mechanisms, along with the impact of the physicochemical properties of nanomaterials, are comprehensively described. Moreover, the different experimental models used for neurotoxicity evaluation are explored at length, including their main advantages and limitations. To conclude, we discuss current challenges and future perspectives for a better understanding of risk assessment of nanocarriers for neurobiomedical applications.

Increased SPARC in brain microvessels of ob/ob mice accelerates molecular transport into the brain accompany with albumin

Cytotoxic metabolites originating from the peripheral circulation can induce central nervous system complications associated with diabetes. Since a large proportion of these metabolites bind to plasma albumin, mechanisms for transporting albumin-metabolite complexes into the brain exist under diabetic conditions. Secreted protein acidic and rich in cysteine (SPARC) is one of the vesicular transport receptors responsible for albumin transport. This study aimed to investigate the changes in SPARC expression and cellular albumin transfer under high-glucose conditions and evaluate the permeability of molecules with high protein-bound properties to the brain tissue. Glucose (30 mM) increased SPARC expression, and intracellular albumin accumulation in NIH3T3 cells. In addition, these changes were observed in the brain of ob/ob mice. Brain microvessels function as a physiological barrier to limit the penetration of molecules from the peripheral blood circulation into the brain by forming tight junctions. Although protein expression of molecules involved in tight junction formation and cell adhesion was increased in the brain microvessels of ob/ob mice, molecular transfer into the brain through cellular junctions was not enhanced. However, Evans blue dye injected into the peripheral vein and endogenous advanced glycation end-products, exerted a high protein-binding property and accumulated in their brains. These observations indicate that peripheral molecules with high protein-binding properties invade the brain tissue and bind to albumin through transcytosis mediated by SPARC.

Biophysical translational paradigm of polymeric nanoparticle: Embarked advancement to brain tumor therapy

Polymeric nanoparticles have emerged as promising contenders for addressing the intricate challenges encountered in brain tumor therapy due to their distinctive attributes, including adjustable size, biocompatibility, and controlled drug release kinetics. This review comprehensively delves into the latest developments in synthesizing, characterizing, and applying polymeric nanoparticles explicitly tailored for brain tumor therapy. Various synthesis methodologies, such as emulsion polymerization, nanoprecipitation, and template-assisted fabrication, are scrutinized within the context of brain tumor targeting, elucidating their advantages and limitations concerning traversing the blood-brain barrier. Furthermore, strategies pertaining to surface modification and functionalization are expounded upon to augment the stability, biocompatibility, and targeting prowess of polymeric nanoparticles amidst the intricate milieu of the brain microenvironment. Characterization techniques encompassing dynamic light scattering, transmission electron microscopy, and spectroscopic methods are scrutinized to evaluate the physicochemical attributes of polymeric nanoparticles engineered for brain tumor therapy. Moreover, a comprehensive exploration of the manifold applications of polymeric nanoparticles encompassing drug delivery, gene therapy, imaging, and combination therapies for brain tumours is undertaken. Special emphasis is placed on the encapsulation of diverse therapeutics within polymeric nanoparticles, thereby shielding them from degradation and enabling precise targeting within the brain. Additionally, recent advancements in stimuli-responsive and multifunctional polymeric nanoparticles are probed for their potential in personalized medicine and theranostics tailored for brain tumours. In essence, this review furnishes an all-encompassing overview of the recent strides made in tailoring polymeric nanoparticles for brain tumor therapy, illuminating their synthesis, characterization, and multifaceted application.

Transforming brain cancer therapeutics: unlocking the power of blood-brain barrier-targeting strategies for superior treatment outcomes and precision medicine

The treatment of brain tumors is significantly hindered by the Blood-Brain Barrier (BBB), a selective barrier that restricts the passage of therapeutic agents to the brain. Recent advancements in BBB-targeting therapies offer promising strategies to overcome this challenge, providing new avenues for the effective treatment of brain cancer. This article reviews innovative approaches, including Convection-Enhanced Delivery (CED) and RNA-based therapeutics, which enhance drug delivery directly to tumor sites, bypassing the BBB and reducing systemic toxicity. Additionally, the use of theranostic nanoparticles and CRISPR-Cas9 gene editing presents novel opportunities for real-time monitoring and precision-targeted therapy, respectively. Techniques such as magnetic nanoparticles, intranasal drug administration, and focused ultrasound with microbubbles are also being refined to improve drug penetration across the BBB. Furthermore, peptide-based delivery systems and small molecules designed to mimic endogenous transport pathways are accelerating the discovery of more effective therapies. The exploration of combination therapies that synergize BBB-penetrant drugs with conventional chemotherapeutic agents or immunotherapies holds the potential to enhance treatment efficacy and patient outcomes. Continued research and interdisciplinary collaboration are essential to develop predictive models, personalized treatment strategies, and alternative delivery methods that ensure the long-term safety and effectiveness of these novel therapies. Advancements in BBB-targeting therapeutics are poised to transform the landscape of brain cancer treatment, offering renewed hope for improved survival rates and quality of life for patients.

Emerging trends in virus and virus-like particle gene therapy delivery to the brain

Recent advances in gene therapy and gene-editing techniques offer the very real potential for successful treatment of neurological diseases. However, drug delivery constraints continue to impede viable therapeutic interventions targeting the brain due to its anatomical complexity and highly restrictive microvasculature that is impervious to many molecules. Realizing the therapeutic potential of gene-based therapies requires robust encapsulation and safe and efficient delivery to the target cells. Although viral vectors have been widely used for targeted delivery of gene-based therapies, drawbacks such as host genome integration, prolonged expression, undesired off-target mutations, and immunogenicity have led to the development of alternative strategies. Engineered virus-like particles (eVLPs) are an emerging, promising platform that can be engineered to achieve neurotropism through pseudotyping. This review outlines strategies to improve eVLP neurotropism for therapeutic brain delivery of gene-editing agents.

A comprehensive review on modeling aspects of infusion-based drug delivery in the brain

Brain disorders represent an ever-increasing health challenge worldwide. While conventional drug therapies are less effective due to the presence of the blood-brain barrier, infusion-based methods of drug delivery to the brain represent a promising option. Since these methods are mechanically controlled and involve multiple physical phases ranging from the neural and molecular scales to the brain scale, highly efficient and precise delivery procedures can significantly benefit from a comprehensive understanding of drug-brain and device-brain interactions. Behind these interactions are principles of biophysics and biomechanics that can be described and captured using mathematical models. Although biomechanics and biophysics have received considerable attention, a comprehensive mechanistic model for modeling infusion-based drug delivery in the brain has yet to be developed. Therefore, this article reviews the state-of-the-art mechanistic studies that can support the development of next-generation models for infusion-based brain drug delivery from the perspective of fluid mechanics, solid mechanics, and mathematical modeling. The supporting techniques and database are also summarized to provide further insights. Finally, the challenges are highlighted and perspectives on future research directions are provided. STATEMENT OF SIGNIFICANCE: Despite the immense potential of infusion-based drug delivery methods for bypassing the blood-brain barrier and efficiently delivering drugs to the brain, achieving optimal drug distribution remains a significant challenge. This is primarily due to our limited understanding of the complex interactions between drugs and the brain that are governed by principles of biophysics and biomechanics, and can be described using mathematical models. This article provides a comprehensive review of state-of-the-art mechanistic studies that can help to unravel the mechanism of drug transport in the brain across the scales, which underpins the development of next-generation models for infusion-based brain drug delivery. More broadly, this review will serve as a starting point for developing more effective treatments for brain diseases and mechanistic models that can be used to study other soft tissue and biomaterials.

Enhanced neuroprotective effect of verapamil-loaded hyaluronic acid modified carbon quantum dots in an in-vitro model of amyloid-induced Alzheimer's disease

This study aims to investigate the molecular mechanisms and the neuroprotective effect of hyaluronic acid modified verapamil-loaded carbon quantum dots (VRH-loaded HA-CQDs) against an in-vitro Alzheimer's disease model induced by amyloid beta (Aβ) in SH-SY5Y and Neuro 2a neuroblastoma cells. Briefly, different HA-CQDs were prepared using hydrothermal method and optimized by Box-Behnken design to maximize quantum yield and minimize particle size. Serum stable negatively charged VRH-loaded HA-CQDs was successfully prepared by admixing the optimized HA-CQDs and VRH with association efficiency and loading capacity of 81.25 ± 3.65 % and 5.11 ± 0.81 %, respectively. Cells were pretreated with VRH solution or loaded-HA-CQDs followed by exposure to Aβ. Compared to the control group, amyloidosis led to reduction in cellular proliferation, mitochondrial membrane potential, expression of cytochrome P450, cytochrome c oxidase, CREB-regulated transcriptional coactivator 3, and mitotic index, along with marked increase in reactive oxygen species (ROS) and inflammatory cytokines. Pretreatment with VRH, either free or loaded HA-CQDs, enhanced cell survival, mitochondrial membrane potential, mitotic index, and gene expression. It also reduced inflammation and ROS. However, VRH-loaded HA-CQDs exhibited superior effectiveness in the measured parameters. These findings suggest that VRH-loaded HA-CQDs have enhanced therapeutic potential compared to free VRH in mitigating amyloidosis negative features.

Burst sine wave electroporation (B-SWE) for expansive blood-brain barrier disruption and controlled non-thermal tissue ablation for neurological disease

The blood-brain barrier (BBB) limits the efficacy of treatments for malignant brain tumors, necessitating innovative approaches to breach the barrier. This study introduces burst sine wave electroporation (B-SWE) as a strategic modality for controlled BBB disruption without extensive tissue ablation and compares it against conventional pulsed square wave electroporation-based technologies such as high-frequency irreversible electroporation (H-FIRE). Using an in vivo rodent model, B-SWE and H-FIRE effects on BBB disruption, tissue ablation, and neuromuscular contractions are compared. Equivalent waveforms were designed for direct comparison between the two pulsing schemes, revealing that B-SWE induces larger BBB disruption volumes while minimizing tissue ablation. While B-SWE exhibited heightened neuromuscular contractions when compared to equivalent H-FIRE waveforms, an additional low-dose B-SWE group demonstrated that a reduced potential can achieve similar levels of BBB disruption while minimizing neuromuscular contractions. Repair kinetics indicated faster closure post B-SWE-induced BBB disruption when compared to equivalent H-FIRE protocols, emphasizing B-SWE's transient and controllable nature. Additionally, finite element modeling illustrated the potential for extensive BBB disruption while reducing ablation using B-SWE. B-SWE presents a promising avenue for tailored BBB disruption with minimal tissue ablation, offering a nuanced approach for glioblastoma treatment and beyond.

Improving drug delivery to the brain: the prodrug approach

INTRODUCTION

The prodrug approach has been thought to be a simple solution to improve brain drug delivery for decades. Nevertheless, it still comes as a surprise that there is relatively little success in the field. The best example anti-parkinsonian drug levodopa has been serendipitously discovered to be a transporter-utilizing brain-delivered prodrug rather than a rationally developed one.

AREAS COVERED

The lack of success can mainly be explained by the insufficient understanding of the role of membrane proteins that can facilitate drug delivery at dynamic barriers, such as the blood-brain barrier (BBB), but also by the sparse knowledge of prodrug bioconverting enzymes in the brain. This review summarizes the current status of the prodrug attempts that have been developed in the past to improve brain drug delivery.

EXPERT OPINION

With the expandingly improved analytical and computational technologies, it is anticipated that enhanced brain drug delivery will be eventually achieved for most of the central nervous system (CNS) acting drugs. However, this requires that carrier-mediated (pro)drug delivery methods are implemented in the very early phases of the drug development processes and not as a last step to survive a problematic investigational drug candidate.

Specific transport of temozolomide does not override DNA repair-mediated chemoresistance

Temozolomide (TMZ) a DNA alkylating agent, is the standard-of-care for brain tumors, such as glioblastoma multiforme (GBM). Although the physicochemical and pharmacokinetic properties of TMZ, such as chemical stability and the ability to cross the blood-brain barrier (BBB), have been questioned in the past, the acquired chemoresistance has been the main limiting factor of long-term clinical use of TMZ. In the present study, an L-type amino acid transporter 1 (LAT1)-utilizing prodrug of TMZ (TMZ-AA, 6) was prepared and studied for its cellular accumulation and cytotoxic properties in human squamous cell carcinoma, UT-SCC-28 and UT-SCC-42B cells, and TMZ-sensitive human glioma, U-87MG cells that expressed functional LAT1. TMZ-AA 6 accumulated more effectively than TMZ itself into those cancer cells that expressed LAT1 (UT-SCC-42B). However, this did not correlate with decreased viability of treated cells. Indeed, TMZ-AA 6, similarly to TMZ itself, required adjuvant inhibitor(s) of DNA-repair systems, O6-methylguanine-DNA methyl transferase (MGMT) and base excision repair (BER), as well as active DNA mismatch repair (MMR), for maximal growth inhibition. The present study shows that improving the delivery of this widely-used methylating agent is not the main barrier to improved chemotherapy, although utilizing a specific transporter overexpressed at the BBB or glioma cells can have targeting advantages. To obtain a more effective anticancer prodrug, the compound design focus should shift to altering the major DNA alkylation site or inhibiting DNA repair systems.

Systemic Treatment with Fas-Blocking Peptide Attenuates Apoptosis in Brain Ischemia

Apoptosis plays a crucial role in neuronal injury, with substantial evidence implicating Fas-mediated cell death as a key factor in ischemic strokes. To address this, inhibition of Fas-signaling has emerged as a promising strategy in preventing neuronal cell death and alleviating brain ischemia. However, the challenge of overcoming the blood-brain barrier (BBB) hampers the effective delivery of therapeutic drugs to the central nervous system (CNS). In this study, we employed a 30 amino acid-long leptin peptide to facilitate BBB penetration. By conjugating the leptin peptide with a Fas-blocking peptide (FBP) using polyethylene glycol (PEG), we achieved specific accumulation in the Fas-expressing infarction region of the brain following systemic administration. Notably, administration in leptin receptor-deficient db/db mice demonstrated that leptin facilitated the delivery of FBP peptide. We found that the systemic administration of leptin-PEG-FBP effectively inhibited Fas-mediated apoptosis in the ischemic region, resulting in a significant reduction of neuronal cell death, decreased infarct volumes, and accelerated recovery. Importantly, neither leptin nor PEG-FBP influenced apoptotic signaling in brain ischemia. Here, we demonstrate that the systemic delivery of leptin-PEG-FBP presents a promising and viable strategy for treating cerebral ischemic stroke. Our approach not only highlights the therapeutic potential but also emphasizes the importance of overcoming BBB challenges to advance treatments for neurological disorders.

BBB opening by low pulsed electric fields, depicted by delayed-contrast MRI, enables efficient delivery of therapeutic doxorubicin doses into mice brains

BACKGROUND

Pharmacological treatment of CNS diseases is limited due to the presence of the blood-brain barrier (BBB). Recent years showed significant advancement in the field of CNS drug delivery enablers, with technologies such as MR-guided focused ultrasound reaching clinical trials. This have inspired researchers in the field to invent novel brain barriers opening (BBo) technologies that are required to be simple, fast, safe and efficient. One such technology, recently developed by us, is BDF (Barrier Disrupting Fields), based on low pulsed electric fields (L-PEFs) for opening the BBB in a controlled, safe, reversible and non-invasive manner. Here, we conducted an in vivo study to show that BDF is a feasible technology for delivering Doxorubicin (Doxo) into mice brain. Means for depicting BBBo levels were developed and applied for monitoring the treatment and predicting response. Overall, the goals of the presented study were to demonstrate the feasibility for delivering therapeutic Doxo doses into naïve and tumor-bearing mice brains and applying delayed-contrast MRI (DCM) for monitoring the levels of BBBo.

METHODS

L-PEFs were applied using plate electrodes placed on the intact skull of naïve mice. L-PEFs/Sham mice were scanned immediately after the procedure by DCM ("MRI experiment"), or injected with Doxo and Trypan blue followed by delayed (4 h) perfusion and brain extraction ("Doxo experiment"). Doxo concentrations were measured in brain samples using confocal microscopy and compared to IC50 of Doxo in glioma cell lines in vitro. In order to map BBBo extent throughout the brain, pixel by pixel MR image analysis was performed using the DCM data. Finally, the efficacy of L-PEFs in combination with Doxo was tested in nude mice bearing intracranial human glioma tumors.

RESULTS

Significant amount of Doxo was found in cortical regions of all L-PEFs-treated mice brains (0.50 ± 0.06 µg Doxo/gr brain) while in Sham brains, Doxo concentrations were below or on the verge of detection limit (0.03 ± 0.02 µg Doxo/gr brain). This concentration was x97 higher than IC50 of Doxo calculated in gl261 mouse glioma cells and x8 higher than IC50 of Doxo calculated in U87 human glioma cells. DCM analysis revealed significant BBBo levels in the cortical regions of L-PEFs-treated mice; the average volume of BBBo in the L-PEFs-treated mice was x29 higher than in the Sham group. The calculated BBBo levels dropped exponentially as a function of BBBo threshold, similarly to the electric fields distribution in the brain. Finally, combining non-invasive L-PEFs with Doxo significantly decreased brain tumors growth rates in nude mice.

CONCLUSIONS

Our results demonstrate significant BBBo levels induced by extra-cranial L-PEFs, enabling efficient delivery of therapeutic Doxo doses into the brain and reducing tumor growth. As BBBo was undetectable by standard contrast-enhanced MRI, DCM was applied to generate maps depicting the BBBo levels throughout the brain. These findings suggest that BDF is a promising technology for efficient drug delivery into the brain with important implications for future treatment of brain cancer and additional CNS diseases.

Strategic nanocarriers to control neurodegenerative disorders: Concept, challenges, and future perspective

Various neurodegenerative diseases (parkinson, huntington, alzheimer, and amyotrophic lateral sclerosis) are becoming serious global health challenges. Despite various treatment options, successful delivery and effective outcomes have been challenged with several physiological-anatomical barriers, formulation related issues, post-administration hurdles, regulatory constraints, physical hurdles, environmental issues, and safety concern. In the present review, we addressed a brief understanding of pathological and normal condition of blood brain barrier (BBB), rational for brain delivery using nanocarriers, major challenges, advantages of nanomedicine, critical aspects of nanomedicine to translate from bed to clinics, and strategic approaches for improved delivery across BBB. The review addressed various mechanistic perspective for delivery of drug loaded nanocarriers across BBB. Moreover, several reports have been published wherein phytomedicine, exosomes, magnetic nanopartilces, functionalized nanocarriers, cationic nanopartilces, and nano-phytomedicine were investigated for remarkable improvement in neurological disorders. These findings are informative for healthcare professionals, researchers, and scientists working in the domains. The successful application and convincing outcomes of nanomedicines were envisaged with clinical trials conducted on various drugs intended to control neurological disorders (NDs). Conclusively, the review addressed comprehensive findings on various aspects of drug loaded nanocarrier delivery across BBB, considerable risks, potential therapeutic benefits, clinical trial based outcomes, and recent advances followed by future perspectives.

Innovative Discoveries in Neurosurgical Treatment of Neurodegenerative Diseases: A Narrative Review

Neurodegenerative diseases (NDDs) encapsulate conditions in which neural cell populations are perpetually degraded and nervous system function destroyed. Generally linked to increased age, the proportion of patients diagnosed with a NDD is growing as human life expectancies rise. Traditional NDD therapies and surgical interventions have been limited. However, recent breakthroughs in understanding disease pathophysiology, improved drug delivery systems, and targeted pharmacologic agents have allowed innovative treatment approaches to treat NDDs. A common denominator for administering these new treatment options is the requirement for neurosurgical skills. In the present narrative review, we highlight exciting and novel preclinical and clinical discoveries being integrated into NDD care. We also discuss the traditional role of neurosurgery in managing these neurodegenerative conditions and emphasize the critical role of neurosurgery in effectuating these newly developed treatments.