Effect of mannose targeting of hydroxyl PAMAM dendrimers on cellular and organ biodistribution in a neonatal brain injury model

To see or not to see: In vivo nanocarrier detection methods in the brain and their challenges

Nanoparticles have a great potential to significantly improve the delivery of therapeutics to the brain and may also be equipped with properties to investigate brain function. The brain, being a highly complex organ shielded by selective barriers, requires its own specialized detection system. However, a significant hurdle to achieve these goals is still the identification of individual nanoparticles within the brain with sufficient cellular, subcellular, and temporal resolution. This review aims to provide a comprehensive summary of the current knowledge on detection systems for tracking nanoparticles across the blood-brain barrier and within the brain. We discuss commonly employed in vivo and ex vivo nanoparticle identification and quantification methods, as well as various imaging modalities able to detect nanoparticles in the brain. Advantages and weaknesses of these modalities as well as the biological factors that must be considered when interpreting results obtained through nanotechnologies are summarized. Finally, we critically evaluate the prevailing limitations of existing technologies and explore potential solutions.

Harnessing nanomedicine for modulating microglial states in the central nervous system disorders: Challenges and opportunities

Microglia are essential for maintaining homeostasis and responding to pathological events in the central nervous system (CNS). Their dynamic and multidimensional states in different environments are pivotal factors in various CNS disorders. However, therapeutic modulation of microglial states is challenging due to the intricate balance these cells maintain in the CNS environment and the blood-brain barrier's restriction of drug delivery. Nanomedicine presents a promising avenue for addressing these challenges, offering a method for the targeted and efficient modulation of microglial states. This review covers the challenges faced in microglial therapeutic modulation and potential use of nanoparticle-based drug delivery systems. We provide an in-depth examination of nanoparticle applications for modulating microglial states in a range of CNS disorders, encompassing neurodegenerative and autoimmune diseases, infections, traumatic injuries, stroke, tumors, chronic pain, and psychiatric conditions. This review highlights the recent advancements and future prospects in nanomedicine for microglial modulation, paving the way for future research and clinical applications of therapeutic interventions in CNS disorders.

Dendrimer nanotherapy targeting of glial dysfunction improves inflammation and neurobehavioral phenotype in adult female Mecp2-heterozygous mouse model of Rett syndrome

Rett syndrome is an X-linked neurodevelopmental disorder caused by mutation of Mecp2 gene and primarily affects females. Glial cell dysfunction has been implicated in in Rett syndrome (RTT) both in patients and in mouse models of this disorder and can affect synaptogenesis, glial metabolism and inflammation. Here we assessed whether treatment of adult (5-6 months old) symptomatic Mecp2-heterozygous female mice with N-acetyl cysteine conjugated to dendrimer (D-NAC), which is known to target glia and modulate inflammation and oxidative injury, results in improved behavioral phenotype, sleep and glial inflammatory profile. We show that unbiased global metabolomic analysis of the hippocampus and striatum in adult Mecp2-heterozygous mice demonstrates significant differences in lipid metabolism associated with neuroinflammation, providing the rationale for targeting glial inflammation in this model. Our results demonstrate that treatment with D-NAC (10 mg/kg NAC) once weekly is more efficacious than equivalently dosed free NAC in improving the gross neurobehavioral phenotype in symptomatic Mecp2-heterozygous female mice. We also show that D-NAC therapy is significantly better than saline in ameliorating several aspects of the abnormal phenotype including paw clench, mobility, fear memory, REM sleep and epileptiform activity burden. Systemic D-NAC significantly improves microglial proinflammatory cytokine production and is associated with improvements in several aspects of the phenotype including paw clench, mobility, fear memory, and REM sleep, and epileptiform activity burden in comparison to saline-treated Mecp2-hetereozygous mice. Systemic glial-targeted delivery of D-NAC after symptom onset in an older clinically relevant Rett syndrome model shows promise in improving neurobehavioral impairments along with sleep pattern and epileptiform activity burden. These findings argue for the translational value of this approach for treatment of patients with Rett Syndrome.

Advanced Nano-Drug Delivery Systems in the Treatment of Ischemic Stroke

In recent years, the frequency of strokes has been on the rise year by year and has become the second leading cause of death around the world, which is characterized by a high mortality rate, high recurrence rate, and high disability rate. Ischemic strokes account for a large percentage of strokes. A reperfusion injury in ischemic strokes is a complex cascade of oxidative stress, neuroinflammation, immune infiltration, and mitochondrial damage. Conventional treatments are ineffective, and the presence of the blood-brain barrier (BBB) leads to inefficient drug delivery utilization, so researchers are turning their attention to nano-drug delivery systems. Functionalized nano-drug delivery systems have been widely studied and applied to the study of cerebral ischemic diseases due to their favorable biocompatibility, high efficiency, strong specificity, and specific targeting ability. In this paper, we briefly describe the pathological process of reperfusion injuries in strokes and focus on the therapeutic research progress of nano-drug delivery systems in ischemic strokes, aiming to provide certain references to understand the progress of research on nano-drug delivery systems (NDDSs).

Mannose Ligands for Mannose Receptor Targeting

The mannose receptor (MR, CD 206) is an endocytic receptor primarily expressed by macrophages and dendritic cells, which plays a critical role in both endocytosis and antigen processing and presentation. MR carbohydrate recognition domains (CRDs) exhibit a high binding affinity for branched and linear oligosaccharides. Furthermore, multivalent mannose presentation on the various templates like peptides, proteins, polymers, micelles, and dendrimers was proven to be a valuable approach for the selective and efficient delivery of various therapeutically active agents to MR. This review provides a detailed account of the most relevant and recent aspects of the synthesis and application of mannosylated bioactive formulations for MR-mediated delivery in treatments of cancer and other infectious diseases. It further highlights recent findings related to the necessary structural features of the mannose-containing ligands for successful binding to the MR.

Microglial-Targeted nSMase2 Inhibitor Fails to Reduce Tau Propagation in PS19 Mice

The progression of Alzheimer's disease (AD) correlates with the propagation of hyperphosphorylated tau (pTau) from the entorhinal cortex to the hippocampus and neocortex. Neutral sphingomyelinase2 (nSMase2) is critical in the biosynthesis of extracellular vesicles (EVs), which play a role in pTau propagation. We recently conjugated DPTIP, a potent nSMase2 inhibitor, to hydroxyl-PAMAM-dendrimer nanoparticles that can improve brain delivery. We showed that dendrimer-conjugated DPTIP (D-DPTIP) robustly inhibited the spread of pTau in an AAV-pTau propagation model. To further evaluate its efficacy, we tested D-DPTIP in the PS19 transgenic mouse model. Unexpectantly, D-DPTIP showed no beneficial effect. To understand this discrepancy, we assessed D-DPTIP's brain localization. Using immunofluorescence and fluorescence-activated cell-sorting, D-DPTIP was found to be primarily internalized by microglia, where it selectively inhibited microglial nSMase2 activity with no effect on other cell types. Furthermore, D-DPTIP inhibited microglia-derived EV release into plasma without affecting other brain-derived EVs. We hypothesize that microglial targeting allowed D-DPTIP to inhibit tau propagation in the AAV-hTau model, where microglial EVs play a central role in propagation. However, in PS19 mice, where tau propagation is independent of microglial EVs, it had a limited effect. Our findings confirm microglial targeting with hydroxyl-PAMAM dendrimers and highlight the importance of understanding cell-specific mechanisms when designing targeted AD therapies.

Advances in modification and delivery of nucleic acid drugs

Nucleic acid-based drugs, such as RNA and DNA drugs, exert their effects at the genetic level. Currently, widely utilized nucleic acid-based drugs include nucleic acid aptamers, antisense oligonucleotides, mRNA, miRNA, siRNA and saRNA. However, these drugs frequently encounter challenges during clinical application, such as poor stability, weak targeting specificity, and difficulties in traversing physiological barriers. By employing chemical modifications of nucleic acid structures, it is possible to enhance the stability and targeting specificity of certain nucleic acid drugs within the body, thereby improving delivery efficiency and reducing immunogenicity. Moreover, utilizing nucleic acid drug carriers can facilitate the transportation of drugs to lesion sites, thereby aiding efficient intracellular escape and promoting drug efficacy within the body. Currently, commonly employed delivery carriers include virus vectors, lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, protein carriers and extracellular vesicles. Nevertheless, individual modifications or delivery carriers alone are insufficient to overcome numerous obstacles. The integration of nucleic acid chemical modifications with drug delivery systems holds promise for achieving enhanced therapeutic effects. However, this approach also presents increased technical complexity and clinical translation costs. Therefore, the development of nucleic acid drug carriers and nucleic acid chemical modifications that are both practical and simple, while maintaining high efficacy, low toxicity, and precise nucleic acid delivery, has become a prominent research focus in the field of nucleic acid drug development. This review comprehensively summarizes the advancements in nucleic acid-based drug modifica-tions and delivery systems. Additionally, strategies to enhance nucleic acid drug delivery efficiency are discussed, with the aim of providing valuable insights for the translational application of nucleic acid drugs.

Non-Invasive Intranasal Delivery of pApoE2: Effect of Multiple Dosing on the ApoE2 Expression in Mice Brain

Chitosan-based polymeric micelles are promising non-viral nanocarriers for safe and targeted gene delivery. Multi-functionalized chitosan polymeric micelles were prepared by grafting fatty acid, cell-penetrating peptide, and mannose on the chitosan backbone. The polymeric micelles were subjected to surface morphology and surface topography using scanning electron microscopy and atomic force microscopy, respectively. The hemotoxic profile of the prepared polymeric micelles was established against erythrocytes and was found to be <5% hemotoxic up to the concentration of 600 µg/mL. In vitro ApoE2 expression in primary astrocytes and neurons was analyzed. Multi-functionalized polymeric micelles produced greater (p < 0.05) transfection in astrocytes and neurons in comparison to mono-functionalized micelles. Intranasal administration of polymeric micelles/pApoE2 polyplex led to significantly higher (p < 0.05) in vivo pApoE2 expression than chitosan and unfunctionalized polymeric micelles-treated mice groups. The outcomes of this study predict that the developed multi-functionalized polymeric micelles could be an effective and safe gene delivery platform to the brain through the intranasal route.

Dendrimers in Corneal Drug Delivery: Recent Developments and Translational Opportunities

Dendrimers are biocompatible organic nanomaterials with unique physicochemical properties, making them the focus of recent research in drug delivery. The cornea of the human eye presents a challenge for drug transit due to its inherently impenetrable nature, requiring nanocarrier-mediated targeted drug delivery. This review intends to examine recent advancements in the use of dendrimers for corneal drug delivery, including their properties and their potential for treating various ocular diseases. The review will also highlight the benefit of the novel technologies that have been developed and applied in the field, such as corneal targeting, drug release kinetics, treatments for dry eye disease, antibacterial drug delivery, corneal inflammation, and corneal tissue engineering. The review seeks to provide a comprehensive overview of the current state of research in this field, along with the translational developments in the field of dendrimer-based therapeutics and imaging agents and inspire the potential for future developments and translational opportunities in dendrimers based corneal drug delivery.

Galactosylated hydroxyl-polyamidoamine dendrimer targets hepatocytes and improves therapeutic outcomes in a severe model of acetaminophen poisoning-induced liver failure

Toxicity to hepatocytes caused by various insults including drugs is a common cause of chronic liver failure requiring transplantation. Targeting therapeutics specifically to hepatocytes is often a challenge since they are relatively nonendocytosing unlike the highly phagocytic Kupffer cells in the liver. Approaches that enable targeted intracellular delivery of therapeutics to hepatocytes have significant promise in addressing liver disorders. We synthesized a galactose-conjugated hydroxyl polyamidoamine dendrimer (D4-Gal) that targets hepatocytes efficiently through the asialoglycoprotein receptors in healthy mice and in a mouse model of acetaminophen (APAP)-induced liver failure. D4-Gal localized specifically in hepatocytes and showed significantly better targeting when compared with the non-Gal functionalized hydroxyl dendrimer. The therapeutic potential of D4-Gal conjugated to N-acetyl cysteine (NAC) was tested in a mouse model of APAP-induced liver failure. A single intravenous dose of a conjugate of D4-Gal and NAC (Gal-d-NAC) improved survival in APAP mice, decreased cellular oxidative injury and areas of necrosis in the liver, even when administered at the delayed time point of 8 h after APAP exposure. Overdose of APAP is the most common cause of acute hepatic injury and liver transplant need in the United States, and is treated with large doses of NAC administered rapidly within 8 h of overdose leading to systemic side effects and poor tolerance. NAC is not effective when treatment is delayed. Our results suggest that D4-Gal is effective in targeting and delivering therapies to hepatocytes and Gal-D-NAC has the potential to salvage and treat liver injury with a broader therapeutic window.

A Glimpse into Dendrimers Integration in Cancer Imaging and Theranostics

Cancer is a result of abnormal cell proliferation. This pathology is a serious health problem since it is a leading cause of death worldwide. Current anti-cancer therapies rely on surgery, radiation, and chemotherapy. However, these treatments still present major associated problems, namely the absence of specificity. Thus, it is urgent to develop novel therapeutic strategies. Nanoparticles, particularly dendrimers, have been paving their way to the front line of cancer treatment, mostly for drug and gene delivery, diagnosis, and disease monitoring. This is mainly derived from their high versatility, which results from their ability to undergo distinct surface functionalization, leading to improved performance. In recent years, the anticancer and antimetastatic capacities of dendrimers have been discovered, opening new frontiers to dendrimer-based chemotherapeutics. In the present review, we summarize the intrinsic anticancer activity of different dendrimers as well as their use as nanocarriers in cancer diagnostics and treatment.

Functionalized PAMAM constructed nanosystems for biomacromolecule delivery

Polyamidoamines (PAMAMs) are a class of dendrimer with monodispersity and controlled topology, which can deliver biologically active macromolecules (e.g., genes and proteins) to specific regions with high efficiency and minimum side effects. In detail, PAMAMs can be functionalized easily by core modification or surface amendment to encapsulate a wide range of biomacromolecules. Besides, self-assembled, cross-linked and hybrid PAMAMs with customized therapeutic purposes are developed as delivery vehicles, which makes PAMAMs promising for biomacromolecule therapy. In this review, we comprehensively summarize the application of PAMAMs in biomacromolecule delivery from the synthesis of functionalized PAMAM carriers to the development of PAMAM-based drug delivery systems. The underlying strategies for PAMAM functionalization and assembly are first systematically discussed, and then the current applications of PAMAMs for biomacromolecule delivery are reviewed. Finally, a brief perspective on the further applications of PAMAMs concludes, aiming to provide insights into developing PAMAM-based biomacromolecule delivery systems.

Dendrimer Technology in Glioma: Functional Design and Potential Applications

Novel therapeutic and diagnostic methods are sorely needed for gliomas, which contribute yearly to hundreds of thousands of cancer deaths worldwide. Despite the outpouring of research efforts and funding aimed at improving clinical outcomes for patients with glioma, the prognosis for high-grade glioma, and especially glioblastoma, remains dire. One of the greatest obstacles to improving treatment efficacy and destroying cancer cells is the safe delivery of chemotherapeutic drugs and biologics to the tumor site at a high enough dose to be effective. Over the past few decades, a burst of research has leveraged nanotechnology to overcome this obstacle. There has been a renewed interest in adapting previously understudied dendrimer nanocarriers for this task. Dendrimers are small, highly modifiable, branched structures featuring binding sites for a variety of drugs and ligands. Recent studies have demonstrated the potential for dendrimers and dendrimer conjugates to effectively shuttle therapeutic cargo to the correct tumor location, permeate the tumor, and promote apoptosis of tumor cells while minimizing systemic toxicity and damage to surrounding healthy brain tissue. This review provides a primer on the properties of dendrimers; outlines the mechanisms by which they can target delivery of substances to the site of brain pathology; and delves into current trends in the application of dendrimers to drug and gene delivery, and diagnostic imaging, in glioma. Finally, future directions for translating these in vitro and in vivo findings to the clinic are discussed.

A Review on Recent Advances in Mannose-Functionalized Targeted Nanocarrier Delivery Systems in Cancer and Infective Therapeutics

Unmodified nanocarriers used in the chemotherapy of cancers and various infectious diseases exhibit prolonged blood circulation time, prevent enzymatic degradation and increase chemical stability of encapsulated therapeutics. However, off-target effect and lack of specificity associated with unmodified nanoparticles (NPs) limit their applications in the health care system. Mannose (Man) receptors with significant overexpression on antigen-presenting cells and macrophages are among the most admired targets for cancer and anti-infective therapeutics. Therefore, development of Man functionalized nanocarriers targeting Man receptors, for target specific drug delivery in the chemotherapy have been extensively studied. Present review expounds diverse Man-conjugated NPs with their potential for targeted drug delivery, improved biodistribution profiles and localization. Additionally, the review gives detailed account of the interactions of mannosylated NPs with various biological systems and their characterization not discussed in earlier published reports is discussed.

Nanosystems for gene therapy targeting brain damage caused by viral infections

Several human pathogens can cause long-lasting neurological damage. Despite the increasing clinical knowledge about these conditions, most still lack efficient therapeutic interventions. Gene therapy (GT) approaches comprise strategies to modify or adjust the expression or function of a gene, thus providing therapy for human diseases. Since recombinant nucleic acids used in GT have physicochemical limitations and can fail to reach the desired tissue, viral and non-viral vectors are applied to mediate gene delivery. Although viral vectors are associated to high levels of transfection, non-viral vectors are safer and have been further explored. Different types of nanosystems consisting of lipids, polymeric and inorganic materials are applied as non-viral vectors. In this review, we discuss potential targets for GT intervention in order to prevent neurological damage associated to infectious diseases as well as the role of nanosized non-viral vectors as agents to help the selective delivery of these gene-modifying molecules. Application of non-viral vectors for delivery of GT effectors comprise a promising alternative to treat brain inflammation induced by viral infections.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Emerging Materials, Wearables, and Diagnostic Advancements in Therapeutic Treatment of Brain Diseases

Among the most critical health issues, brain illnesses, such as neurodegenerative conditions and tumors, lower quality of life and have a significant economic impact. Implantable technology and nano-drug carriers have enormous promise for cerebral brain activity sensing and regulated therapeutic application in the treatment and detection of brain illnesses. Flexible materials are chosen for implantable devices because they help reduce biomechanical mismatch between the implanted device and brain tissue. Additionally, implanted biodegradable devices might lessen any autoimmune negative effects. The onerous subsequent operation for removing the implanted device is further lessened with biodegradability. This review expands on current developments in diagnostic technologies such as magnetic resonance imaging, computed tomography, mass spectroscopy, infrared spectroscopy, angiography, and electroencephalogram while providing an overview of prevalent brain diseases. As far as we are aware, there hasn't been a single review article that addresses all the prevalent brain illnesses. The reviewer also looks into the prospects for the future and offers suggestions for the direction of future developments in the treatment of brain diseases.

Current approaches to facilitate improved drug delivery to the central nervous system

Although many pharmaceuticals have therapeutic potentials for central nervous system (CNS) diseases, few of these agents have been effectively administered. It is due to the fact that the blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier (BCSF) restrict them from crossing the brain to exert biological activity. This article reviews the current approaches aiming to improve penetration across these barriers for effective drug delivery to the CNS. These issues are summarized into direct systemic delivery and invasive delivery, including the BBB disruption and convection enhanced delivery. Furthermore, novel drug delivery systems used at the nanoscale, including polymeric nanoparticles, liposomes, nanoemulsions, dendrimers, and micelles are discussed. These nanocarriers could contribute to a breakthrough in the treatment of many different CNS diseases. However, further broadened studies are needed to assess the biocompatibility and safety of these medical devices.

Polymeric Dendrimers as Nanocarrier Vectors for Neurotheranostics

Dendrimers are polymers with well-defined 3D branched structures that are vastly utilized in various neurotheranostics and biomedical applications, particularly as nanocarrier vectors. Imaging agents can be loaded into dendrimers to improve the accuracy of diagnostic imaging processes. Likewise, combining pharmaceutical agents and anticancer drugs with dendrimers can enhance their solubility, biocompatibility, and efficiency. Practically, by modifying ligands on the surface of dendrimers, effective therapeutic and diagnostic platforms can be constructed and implemented for targeted delivery. Dendrimer-based nanocarriers also show great potential in gene delivery. Since enzymes can degrade genetic materials during their blood circulation, dendrimers exhibit promising packaging and delivery alternatives, particularly for central nervous system (CNS) treatments. The DNA and RNA encapsulated in dendrimers represented by polyamidoamine that are used for targeted brain delivery, via chemical-structural adjustments and appropriate generation, significantly improve the correlation between transfection efficiency and cytotoxicity. This article reports a comprehensive review of dendrimers' structures, synthesis processes, and biological applications. Recent progress in diagnostic imaging processes and therapeutic applications for cancers and other CNS diseases are presented. Potential challenges and future directions in the development of dendrimers, which provide the theoretical basis for their broader applications in healthcare, are also discussed.

Dendrimer-Conjugated nSMase2 Inhibitor Reduces Tau Propagation in Mice

Alzheimer's disease (AD) is characterized by the progressive accumulation of amyloid-β and hyperphosphorylated tau (pTau), which can spread throughout the brain via extracellular vesicles (EVs). Membrane ceramide enrichment regulated by the enzyme neutral sphingomyelinase 2 (nSMase2) is a critical component of at least one EV biogenesis pathway. Our group recently identified 2,6-Dimethoxy-4-(5-Phenyl-4-Thiophen-2-yl-1H-Imidazol-2-yl)-Phenol (DPTIP), the most potent (30 nM) and selective inhibitor of nSMase2 reported to date. However, DPTIP exhibits poor oral pharmacokinetics (PK), modest brain penetration, and rapid clearance, limiting its clinical translation. To enhance its PK properties, we conjugated DPTIP to a hydroxyl-PAMAM dendrimer delivery system, creating dendrimer-DPTIP (D-DPTIP). In an acute brain injury model, orally administered D-DPTIP significantly reduced the intra-striatal IL-1β-induced increase in plasma EVs up to 72 h post-dose, while oral DPTIP had a limited effect. In a mouse tau propagation model, where a mutant hTau (P301L/S320F) containing adeno-associated virus was unilaterally seeded into the hippocampus, oral D-DPTIP (dosed 3× weekly) significantly inhibited brain nSMase2 activity and blocked the spread of pTau to the contralateral hippocampus. These data demonstrate that dendrimer conjugation of DPTIP improves its PK properties, resulting in significant inhibition of EV propagation of pTau in mice. Dendrimer-based delivery of DPTIP has the potential to be an exciting new therapeutic for AD.

D-mannose functionalized MgAl-LDH/Fe-MOF nanocomposite as a new intelligent nanoplatform for MTX and DOX co-drug delivery

Commonly the directly administered chemotherapy drugs lack targeting in tumor treatment. Thus, trying to improve cancer treatment efficiency led us to design a new intelligent system for cancer treatment. Considering these, in the current work, at first, the 2-aminoterephthalic acid (NH₂-BDC) intercalated layered double hydroxides (MgAl-(NH₂-BDC) LDH) were synthesized simply. Afterward, the in situ growth of the iron-based metal-organic frameworks in the presence of MgAl-(NH₂-BDC) LDH occurred (MgAl-LDH/Fe-MOF). In the end, the reaction of MgAl-LDH/Fe-MOF with D-mannose (D-Man) achieved the MgAl-LDH/Fe-MOF/D-Man ternary hybrid nanostructure. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) analysis confirmed the formation of the monodisperse Fe-MOF with nanosize in the presence of MgAl-LDH. Importantly, methotrexate (MTX) and doxorubicin (DOX) entrapment efficiency reached respectively about 28 wt% and 21% for MgAl-LDH/Fe-MOF/D-Man. The in vitro drug release experiments revealed a higher drug release at pH 5.0 in comparison with pH 7.4 which revealed its promising potential for anticancer drug delivery applications. Bioassay results revealed that the co-drug-loaded MgAl-LDH/Fe-MOF/D-Man has higher cytotoxicity on MDA-MB 231 cells. At last, fluorescence microscopy and flow cytometric analysis confirmed the successful uptake of MgAl-LDH/Fe-MOF/D-Man into MDA-MB 231 cell lines, as well as its bioimaging potential. A survey in the published literature approved that this work is the first report on the evaluation of the MgAl-LDH/Fe-MOF/D-Man for targeted co-delivery of both MTX and DOX. Finally, results collectively demonstrate the importance of the biocompatible MgAl-LDH/Fe-MOF/D-Man as a hopeful candidate for biomedicinal applications from the targeted co-drug delivery and bioimaging potential viewpoints.

Blood-brain barrier Permeable nanoparticles for Alzheimer's disease treatment by selective mitophagy of microglia

Current treatments for Alzheimer's disease (AD) that focus on inhibition of Aβ aggregation failed to show effectiveness in people who already had Alzheimer's symptoms. Strategies that synergistically exert neuroprotection and alleviation of oxidative stress could be a promising approach to correct the pathological brain microenvironment. Based on the key roles of microglia in modulation of AD microenvironment, we describe here the development of Prussian blue/polyamidoamine (PAMAM) dendrimer/Angiopep-2 (PPA) nanoparticles that can regulate the mitophagy of microglia as a potential AD treatment. PPA nanoparticles exhibit superior blood-brain barrier (BBB) permeability and exert synergistic effects of ROS scavenging and restoration of mitochondrial function of microglia. PPA nanoparticles effectively reduce neurotoxic Aβ aggregate and rescue the cognitive functions in APP/PS1 model mice. Together, our data suggest that these multifunctional dendrimer nanoparticles exhibit efficient neuroprotection and microglia modulation and can be exploited as a promising approach for the treatment of AD.

Applications of Various Types of Nanomaterials for the Treatment of Neurological Disorders

Neurological disorders (NDs) are recognized as one of the major health concerns globally. According to the World Health Organization (WHO), neurological disorders are one of the main causes of mortality worldwide. Neurological disorders include Alzheimer’s disease, Parkinson′s disease, Huntington′s disease, Amyotrophic lateral sclerosis, Frontotemporal dementia, Prion disease, Brain tumor, Spinal cord injury, and Stroke. These diseases are considered incurable diseases because no specific therapies are available to cross the blood-brain barrier (BBB) and reach the brain in a significant amount for the pharmacological effect in the brain. There is a need for the development of strategies that can improve the efficacy of drugs and circumvent BBB. One of the promising approaches is the use of different types of nano-scale materials. These nano-based drugs have the ability to increase the therapeutic effect, reduce toxicity, exhibit good stability, targeted delivery, and drug loading capacity. Different types and shapes of nanomaterials have been widely used for the treatment of neurological disorders, including quantum dots, dendrimers, metallic nanoparticles, polymeric nanoparticles, carbon nanotubes, liposomes, and micelles. These nanoparticles have unique characteristics, including sensitivity, selectivity, and the ability to cross the BBB when used in nano-sized particles, and are widely used for imaging studies and treatment of NDs. In this review, we briefly summarized the recent literature on the use of various nanomaterials and their mechanism of action for the treatment of various types of neurological disorders.

New Approaches to Dendritic Cell-Based Therapeutic Vaccines Against HIV-1 Infection

Due to the success of combined antiretroviral therapy (cART) in recent years, the pathological outcome of Human Immunodeficiency Virus type 1 (HIV-1) infection has improved substantially, achieving undetectable viral loads in most cases. Nevertheless, the presence of a viral reservoir formed by latently infected cells results in patients having to maintain treatment for life. In the absence of effective eradication strategies against HIV-1, research efforts are focused on obtaining a cure. One of these approaches is the creation of therapeutic vaccines. In this sense, the most promising one up to now is based on the establishing of the immunological synapse between dendritic cells (DCs) and T lymphocytes (TL). DCs are one of the first cells of the immune system to encounter HIV-1 by acting as antigen presenting cells, bringing about the interaction between innate and adaptive immune responses mediated by TL. Furthermore, TL are the end effector, and their response capacity is essential in the adaptive elimination of cells infected by pathogens. In this review, we summarize the knowledge of the interaction between DCs with TL, as well as the characterization of the specific T-cell response against HIV-1 infection. The use of nanotechnology in the design and improvement of vaccines based on DCs has been researched and presented here with a special emphasis.

Dendrimer-2PMPA selectively blocks upregulated microglial GCPII activity and improves cognition in a mouse model of multiple sclerosis

Cognitive impairment is a common aspect of multiple sclerosis (MS) for which there are no treatments. Reduced brain N-acetylaspartylglutamate (NAAG) levels are linked to impaired cognition in various neurological diseases, including MS. NAAG levels are regulated by glutamate carboxypeptidase II (GCPII), which hydrolyzes the neuropeptide to N-acetyl-aspartate and glutamate. GCPII activity is upregulated multifold in microglia following neuroinflammation. Although several GCPII inhibitors, such as 2-PMPA, elevate brain NAAG levels and restore cognitive function in preclinical studies when given at high systemic doses or via direct brain injection, none are clinically available due to poor bioavailability and limited brain penetration. Hydroxyl-dendrimers have been successfully used to selectively deliver drugs to activated glia.

Methods: We attached 2-PMPA to hydroxyl polyamidoamine (PAMAM) dendrimers (D-2PMPA) using a click chemistry approach. Cy5-labelled-D-2PMPA was used to visualize selective glial uptake in vitro and in vivo. D-2PMPA was evaluated for anti-inflammatory effects in LPS-treated glial cultures. In experimental autoimmune encephalomyelitis (EAE)-immunized mice, D-2PMPA was dosed biweekly starting at disease onset and cognition was assessed using the Barnes maze, and GCPII activity was measured in CD11b+ hippocampal cells.

Results: D-2PMPA showed preferential uptake into microglia and robust anti-inflammatory activity, including elevations in NAAG, TGFβ, and mGluR3 in glial cultures. D-2PMPA significantly improved cognition in EAE mice, even though physical severity was unaffected. GCPII activity increased >20-fold in CD11b+ cells from EAE mice, which was significantly mitigated by D-2PMPA treatment.

Conclusions: Hydroxyl dendrimers facilitate targeted drug delivery to activated microglia. These data support further development of D-2PMPA to attenuate elevated microglial GCPII activity and treat cognitive impairment in MS.

Computer simulation of the Receptor-Ligand Interactions of Mannose Receptor CD206 in Comparison with the Lectin Concanavalin A Model

Computer modeling of complexation of mono- and oligosaccharide ligands with the main (fourth) carbohydrate-binding domain of the mannose receptor CD206 (CRD4), as well as with the model receptor concanavalin A (ConA), was carried out for the first time, using methods of molecular dynamics and neural network analysis. ConA was shown to be a relevant model of CD206 (CRD4) due to similarity of the structural organization of the binding sites and high correlation of the values of free energies of complexation between the literature data and computer modeling (r > 0.9). Role of the main factors affecting affinity of the ligand–receptor interactions is discussed: the number and nature of carbohydrate residues, presence of Me-group in the O1 position, type of the glycoside bond in dimannose. Complexation of ConA and CD206 with ligands is shown to be energetically caused by electrostatic interactions (E) of the charged residues (Asn, Asp, Arg) with oxygen and hydrogen atoms in carbohydrates; contributions of hydrophobic and van der Waals components is lower. Possibility of the additional stabilization of complexes due to the CH–π stacking interactions of Tyr with the Man plane is discussed. The role of calcium and manganese ions in binding ligands has been studied. The values of free energies of complexation calculated in the course of molecular dynamics simulation correlate with experimental data (published for the model ConA): correlation coefficient r = 0.68. The Pafnucy neural network was trained based on the set of PDBbind2020 ligand–receptor complexes, which significantly increased accuracy of the energy predictions to r = 0.8 and 0.82 for CD206 and ConA receptors, respectively. A model of normalization of the complexation energy values for calculating the relevant values of ΔG_bind, K_d is proposed. Based on the developed technique, values of the dissociation constants of a series of CD206 complexes with nine carbohydrate ligands of different structures were determined, which were not previously known. The obtained data open up possibilities for using computer modeling for the development of optimal drug carriers capable of active macrophage targeting, and also determine the limits of applicability of using ConA as a relevant model for studying parameters of the CD206 binding to various carbohydrate ligands.

Dendrimer-2PMPA Delays Muscle Function Loss and Denervation in a Murine Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating neurodegenerative disease where muscle weakness and neuromuscular junction (NMJ) denervation precede motor neuron cell death. Although acetylcholine is the canonical neurotransmitter at the mammalian NMJ synapse, glutamate has recently been identified as a critical neurotransmitter for NMJ development and maintenance. One source of glutamate is through the catabolism of N-acetyl-aspartyl-glutamate (NAAG), which is found in mM concentrations in mammalian motoneurons, where it is released upon stimulation and hydrolyzed to glutamate by the glial enzyme glutamate carboxypeptidase II (GCPII). Using the SOD1G93A model of ALS, we found an almost fourfold elevation of GCPII enzymatic activity in SOD1G93A versus WT muscle and a robust increase in GCPII expression which was specifically associated with activated macrophages infiltrating the muscle. 2-(Phosphonomethyl)pentanedioic acid (2PMPA) is a potent GCPII inhibitor which robustly blocks glutamate release from NAAG but is highly polar with limited tissue penetration. To improve this, we covalently attached 2PMPA to a hydroxyl polyamidoamine (PAMAM-G4-OH) dendrimer delivery system (D-2PMPA) which is known to target activated macrophages in affected tissues. Systemic D-2PMPA therapy (20 mg/kg 2PMPA equivalent; IP 2 × /week) was found to localize in muscle macrophages in SOD1G93A mice and completely normalize the enhanced GCPII activity. Although no changes in body weight or survival were observed, D-2PMPA significantly improved grip strength and inhibited the loss of NMJ innervation in the gastrocnemius muscles. Our finding that inhibiting elevated GCPII activity in SOD1G93A muscle can prolong muscle function and delay NMJ denervation may have early therapeutic implications for ALS patients.

Systemic administration of dendrimer N-acetyl cysteine improves outcomes and survival following cardiac arrest

Cardiac arrest (CA), the sudden cessation of effective cardiac pumping function, is still a major clinical problem with a high rate of early and long-term mortality. Post-cardiac arrest syndrome (PCAS) may be related to an early systemic inflammatory response leading to exaggerated and sustained neuroinflammation. Therefore, early intervention with targeted drug delivery to attenuate neuroinflammation may greatly improve therapeutic outcomes. Using a clinically relevant asphyxia CA model, we demonstrate that a single (i.p.) dose of dendrimer-N-acetylcysteine conjugate (D-NAC), can target "activated" microglial cells following CA, leading to an improvement in post-CA survival rate compared to saline (86% vs. 45%). D-NAC treatment also significantly improved gross neurological score within 4 h of treatment (p < 0.05) and continued to show improvement at 48 h (p < 0.05). Specifically, there was a substantial impairment in motor responses after CA, which was subsequently improved with D-NAC treatment (p < 0.05). D-NAC also mitigated hippocampal cell density loss seen post-CA in the CA1 and CA3 subregions (p < 0.001). These results demonstrate that early therapeutic intervention even with a single D-NAC bolus results in a robust sustainable improvement in long-term survival, short-term motor deficits, and neurological recovery. Our current work lays the groundwork for a clinically relevant therapeutic approach to treating post-CA syndrome.

Current and Emerging Strategies for Enhancing Antibody Delivery to the Brain

For the treatment of neurological diseases, achieving sufficient exposure to the brain parenchyma is a critical determinant of drug efficacy. The blood-brain barrier (BBB) functions to tightly control the passage of substances between the bloodstream and the central nervous system, and as such poses a major obstacle that must be overcome for therapeutics to enter the brain. Monoclonal antibodies have emerged as one of the best-selling treatment modalities available in the pharmaceutical market owing to their high target specificity. However, it has been estimated that only 0.1% of peripherally administered antibodies can cross the BBB, contributing to the low success rate of immunotherapy seen in clinical trials for the treatment of neurological diseases. The development of new strategies for antibody delivery across the BBB is thereby crucial to improve immunotherapeutic efficacy. Here, we discuss the current strategies that have been employed to enhance antibody delivery across the BBB. These include (i) focused ultrasound in combination with microbubbles, (ii) engineered bi-specific antibodies, and (iii) nanoparticles. Furthermore, we discuss emerging strategies such as extracellular vesicles with BBB-crossing properties and vectored antibody genes capable of being encapsulated within a BBB delivery vehicle.

Embracing nanomaterials' interactions with the innate immune system

Immunotherapy has firmly established itself as a compelling avenue for treating disease. Although many clinically approved immunotherapeutics engage the adaptive immune system, therapeutically targeting the innate immune system remains much less explored. Nanomedicine offers a compelling opportunity for innate immune system engagement, as many nanomaterials inherently interact with myeloid cells (e.g., monocytes, macrophages, neutrophils, and dendritic cells) or can be functionalized to target their cell-surface receptors. Here, we provide a perspective on exploiting nanomaterials for innate immune system regulation. We focus on specific nanomaterial design parameters, including size, form, rigidity, charge, and surface decoration. Furthermore, we examine the potential of high-throughput screening and machine learning, while also providing recommendations for advancing the field. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Glycosylation of PAMAM dendrimers significantly improves tumor macrophage targeting and specificity in glioblastoma

Glioblastoma is among the most aggressive forms of cancers, with a median survival of just 15-20 months for patients despite maximum clinical intervention. The majority of conventional anti-cancer therapies fail due to associated off-site toxicities which can be addressed by developing target-specific drug delivery systems. Advances in nanotechnology have provided targeted systems to overcome drug delivery barriers associated with brain and other types of cancers. Dendrimers have emerged as promising vehicles for targeted drug and gene delivery. Dendrimer-mediated targeting strategies can be further enhanced through the addition of targeting ligands to enable receptor-specific interactions. Here, we explore the sugar moieties as ligands conjugated to hydroxyl-terminated polyamidoamine dendrimers to leverage altered metabolism in cancer and immune targeting. Using a highly facile click chemistry approach, we modified the surface of dendrimers with glucose, mannose, or galactose moieties in a well-defined manner, to target upregulated sugar transporters in the context of glioblastoma. We show that glucose modification significantly enhanced targeting of tumor-associated macrophages (TAMs) and microglia by increasing brain penetration and cellular internalization, while galactose modification shifts targeting away from TAMs towards galectins on glioblastoma tumor cells. Mannose modification did not alter TAMs and microglia targeting of these dendrimers, but did alter their kinetics of accumulation within the GBM tumor. The whole body biodistribution was largely similar between the systems. These results demonstrate that dendrimers are versatile delivery vehicles that can be modified to tailor their targeting for the treatment of glioblastoma and other cancers.

Rationally Designed Galactose Dendrimer for Hepatocyte-Specific Targeting and Intracellular Drug Delivery for the Treatment of Liver Disorders

Over two million people die of liver disorders every year globally. Hepatocytes are the key cells affected in several acute and chronic liver diseases. The current clinical outcomes of liver-targeted nanoparticles are limited, necessitating the need to develop smart hepatocyte-targeted drug delivery systems. Here, we present the rational design and development of a hepatocyte-targeting glycodendrimer (GAL-24) built from biocompatible building blocks, using expedite and facile chemical methodology. GAL-24 is designed to inherently target asialoglycoprotein receptor 1 (ASGP-R) on hepatocytes and shows significant accumulation in the liver (20% of injected dose), just 1 h after systemic administration. This is highly specific to hepatocytes, with over 80% of hepatocytes showing GAL-24-Cy5 signal at 24 h. GAL-24-Cy5 maintains hepatocyte-targeting capabilities in both a mouse model of severe acetaminophen poisoning-induced hepatic necrosis and a rat model of nonalcoholic steatohepatitis (NASH). This GAL-24 nanoplatform holds great promise for improved drug delivery to hepatocytes to combat many liver disorders.

Next generation strategies for preventing preterm birth

Preterm birth (PTB) is defined as delivery before 37 weeks of gestation. Globally, 15 million infants are born prematurely, putting these children at an increased risk of mortality and lifelong health challenges. Currently in the U.S., there is only one FDA approved therapy for the prevention of preterm birth. Makena is an intramuscular progestin injection given to women who have experienced a premature delivery in the past. Recently, however, Makena failed a confirmatory trial, resulting the Center for Drug Evaluation and Research's (CDER) recommendation for the FDA to withdrawal Makena's approval. This recommendation would leave clinicians with no therapeutic options for preventing PTB. Here, we outline recent interdisciplinary efforts involving physicians, pharmacologists, biologists, chemists, and engineers to understand risk factors associated with PTB, to define mechanisms that contribute to PTB, and to develop next generation therapies for preventing PTB. These advances have the potential to better identify women at risk for PTB, prevent the onset of premature labor, and, ultimately, save infant lives.

Development of Polymeric Nanoparticles for Blood-Brain Barrier Transfer-Strategies and Challenges

Neurological disorders such as Alzheimer's disease, stroke, and brain cancers are difficult to treat with current drugs as their delivery efficacy to the brain is severely hampered by the presence of the blood-brain barrier (BBB). Drug delivery systems have been extensively explored in recent decades aiming to circumvent this barrier. In particular, polymeric nanoparticles have shown enormous potentials owing to their unique properties, such as high tunability, ease of synthesis, and control over drug release profile. However, careful analysis of their performance in effective drug transport across the BBB should be performed using clinically relevant testing models. In this review, polymeric nanoparticle systems for drug delivery to the central nervous system are discussed with an emphasis on the effects of particle size, shape, and surface modifications on BBB penetration. Moreover, the authors critically analyze the current in vitro and in vivo models used to evaluate BBB penetration efficacy, including the latest developments in the BBB-on-a-chip models. Finally, the challenges and future perspectives for the development of polymeric nanoparticles to combat neurological disorders are discussed.

There and back again: a dendrimer's tale

The development of molecular nanostructures with well-defined particle size and shape is of eminent interest in biomedicine. Among many studied nanostructures, dendrimers represent the group of those most thoroughly characterized ones. Due to their unique structure and properties, dendrimers are very attractive for medical and pharmaceutical applications. Owing to the controllable cavities inside the dendrimer, guest molecules may be encapsulated, and highly reactive terminal groups are susceptible to further modifications, e.g., to facilitate target delivery. To understand the potential of these nanoparticles and to predict and avoid any adverse cellular reactions, it is necessary to know the mechanisms responsible for an efficient dendrimer uptake and the destination of their intracellular journey. In this article, we summarize the results of studies describing the dendrimer uptake, traffic, and efflux mechanisms depending on features of specific nanoparticles and cell types. We also present mechanisms of dendrimers responsible for toxicity and alteration in signal transduction pathways at the cellular level.

Dendrimer-tesaglitazar conjugate induces a phenotype shift of microglia and enhances β-amyloid phagocytosis

Switching microglia from a disease exacerbating, 'pro-inflammatory' state into a neuroprotective, 'anti-inflammatory' phenotype is a promising strategy for addressing multiple neurodegenerative diseases. Pro-inflammatory microglia contribute to disease progression by releasing neurotoxic substances and accelerating pathogenic protein accumulation. PPARα and PPARγ agonists have both been shown to shift microglia from a pro-inflammatory ('M1-like') to an alternatively activated ('M2-like') phenotype. Such strategies have been explored in clinical trials for neurological diseases, such as Alzheimer's and Parkinson's disease, but have likely failed due to their poor blood-brain barrier (BBB) penetration. Hydroxyl-terminated polyamidoamine dendrimers (without the attachment of any targeting ligands) have been shown to cross the impaired BBB at the site of neuroinflammation and accumulate in activated microglia. Therefore, dendrimer conjugation of a PPARα/γ dual agonist may enable targeted phenotype switching of activated microglia. Here we present the synthesis and characterization of a novel dendrimer-PPARα/γ dual agonist conjugate (D-tesaglitazar). In vitro, D-tesaglitazar induces an 'M1 to M2' phenotype shift, decreases secretion of reactive oxygen species, increases expression of genes for phagocytosis and enzymatic degradation of pathogenic proteins (e.g. β-amyloid, α-synuclein), and increases β-amyloid phagocytosis. These results support further development of D-tesaglitazar towards translation for multiple neurodegenerative diseases, especially Alzheimer's and Parkinson's Disease.

Systemic dendrimer delivery of triptolide to tumor-associated macrophages improves anti-tumor efficacy and reduces systemic toxicity in glioblastoma

Novel delivery strategies are necessary to effectively address glioblastoma without systemic toxicities. Triptolide is a therapy derived from the thunder god vine that has shown potent anti-proliferative and immunosuppressive properties but exhibits significant adverse systemic effects. Dendrimer-based nanomedicines have shown great potential for clinical translation of systemic therapies targeting neuroinflammation and brain tumors. Here we present a novel dendrimer-triptolide conjugate that specifically targets tumor-associated macrophages (TAMs) in glioblastoma from systemic administration and exhibits triggered release under intracellular and intratumor conditions. This targeted delivery improves phenotype switching of TAMs from pro- towards anti-tumor expression in vitro. In an orthotopic model of glioblastoma, dendrimer-triptolide achieved significantly improved amelioration of tumor burden compared to free triptolide. Notably, the triggered release mechanism of dendrimer-mediated triptolide delivery significantly reduced triptolide-associated hepatic and cardiac toxicities. These results demonstrate that dendrimers are a promising targeted delivery platform to achieve effective glioblastoma treatment by improving efficacy while reducing systemic toxicities.

Neuroprotective effects of a dendrimer-based glutamate carboxypeptidase inhibitor on superoxide dismutase transgenic mice after neonatal hypoxic-ischemic brain injury

The result of a deprivation of oxygen and glucose to the brain, hypoxic-ischemic encephalopathy (HIE), remains the most common cause of death and disability in human neonates globally and is mediated by glutamate toxicity and inflammation. We have previously shown that the enzyme glutamate carboxypeptidase (GCPII) is overexpressed in activated microglia in the presence of inflammation in fetal/newborn rabbit brain. We assessed the therapeutic utility of a GCPII enzyme inhibitor called 2-(3-Mercaptopropyl) pentanedioic acid (2MPPA) attached to a dendrimer (D-2MPPA), in order to target activated microglia in an experimental neonatal hypoxia-ischemia (HI) model using superoxide dismutase transgenic (SOD) mice that are often more injured after hypoxia-ischemia than wildtype animals. SOD overexpressing and wild type (WT) mice underwent permanent ligation of the left common carotid artery followed by 50 min of asphyxiation (10% O₂) to induce HI injury on postnatal day 9 (P9). Cy5-labeled dendrimers were administered to the mice at 6 h, 24 h or 72 h after HI and brains were evaluated by immunofluorescence analysis 24 h after the injection to visualize microglial localization and uptake over time. Expression of GCPII enzyme was analyzed in microglia 24 h after the HI injury. The expression of pro- and anti-inflammatory cytokines were analyzed 24 h and 72 h post-HI. Brain damage was analyzed histologically 7 days post-HI in the three randomly assigned groups: control (C); hypoxic-ischemic (HI); and HI mice who received a single dose of D-2MPPA 6 h post-HI (HI+D-2MPPA). First, we found that GCPII was overexpressed in activated microglia 24 h after HI in the SOD overexpressing mice. Also, there was an increase in microglial activation 24 h after HI in the ipsilateral hippocampus which was most visible in the SOD+HI group. Dendrimers were mostly taken up by microglia by 24 h post-HI; uptake was more prominent in the SOD+HI mice than in the WT+HI. The inflammatory profile showed significant increase in expression of KC/GRO following injury in SOD mice compared to WT at 24 and 72 h. A greater and significant decrease in KC/GRO was seen in the SOD mice following treatment with D-2MPPA. Seven days after HI, D-2MPPA treatment decreased brain injury in the SOD+HI group, but not in WT+HI. This reduced damage was mainly seen in hippocampus and cortex. Our data indicate that the best time point to administer D-2MPPA is 6 h post-HI in order to suppress the expression of GCPII by 24 h after the damage since dendrimer localization in microglia is seen as early as 6 h with the peak of GCPII upregulation in activated microglia seen at 24 h post-HI. Ultimately, treatment with D-2MPPA at 6 h post-HI leads to a decrease in inflammatory profiles by 24 h and reduction in brain injury in the SOD overexpressing mice.

Dendrimer-Mediated Targeted Delivery of Rapamycin to Tumor-Associated Macrophages Improves Systemic Treatment of Glioblastoma

Glioblastoma exhibits high mortality rates due to challenges with drug delivery to the brain and into solid tumors. This two-pronged barrier necessitates high doses of systemic therapies, resulting in significant off-target toxicities. Recently, dendrimer-nanomedicines (without ligands) have shown promise for targeting specific cells in brain tumors from systemic circulation, for improved efficacy and amelioration of systemic toxicities. A dendrimer-rapamycin conjugate (D-Rapa) is presented here that specifically targets tumor-associated macrophages (TAMs) in glioblastoma from systemic administration. D-Rapa improves suppression of pro-tumor expression in activated TAMs and antiproliferative properties of rapamycin in glioma cells in vitro. In vivo, D-Rapa localizes specifically within TAMs, acting as depots to release rapamycin into the tumor microenvironment. This targeted delivery strategy yields improved reduction in tumor burden and systemic toxicities in a challenging, clinically relevant orthotopic syngeneic model of glioblastoma, demonstrating the significant potential of dendrimers as targeted immunotherapies for improving glioblastoma treatment, still an unmet need.

Mannose receptor 1 expression does not determine the uptake of high-density mannose dendrimers by activated macrophages populations

The presence of a high number of macrophages within solid tumors is often significantly associated with poor prognosis and predict treatment failure for chemotherapy and radiotherapy. Macrophages are innate immune cells capable of performing diverse functions depending on the different signals from the microenvironment. The classically activated macrophage is commonly present during the early stages of tumor development while alternatively activated macrophages are associated with more advanced tumors. The distinction of the antitumoral macrophages from the pro-tumoral macrophages is not absolute. However, they have different cell surface markers such as mannose receptor (MRC1 or CD206) abundantly expressed by macrophages treated with interleukin-4 (IL-4). The important roles of macrophages in cancers suggest that it is important to develop novel therapies that target these cells. In the present study, we designed a probe using Polyamidoamine (PAMAM) fifth-generation (G5) dendrimers conjugated with mannose, Cyanine 7 (Cy7), and hydrazinonicotinamide (HYNIC) for target macrophages with high expression of MRC1 in the tumor. The intracellular uptake of 99mTc-HYNIC-dendrimer-mannose-Cy7 through the interaction with MRC1 in bone marrow-derived macrophages (BMDMs) untreated or treated with lipopolysaccharides (LPS) + interferon (IFN)γ or IL-4 was analyzed. Our results show that high-density mannose dendrimers are preferentially bound by macrophages treated by IFNγ and LPS that express lower levels of MRC1 than for macrophages treated by IL-4 that express high levels of MRC1. Furthermore, the intracellular 99mTc-HYNIC-dendrimer-mannose-Cy7 uptake in BMDMs was not inhibited in the presence of free mannose or glucose. This result suggests that 99mTc-HYNIC-dendrimer-mannose-Cy7 is not internalized via macrophage MRC1. Based on these findings, we concluded that MRC1 expression does not determine the uptake of high-density mannose dendrimers.

Dendrimers as Modulators of Brain Cells

Nanostructured hyperbranched macromolecules have been extensively studied at the chemical, physical and morphological levels. The cellular structural and functional complexity of neural cells and their cross-talk have made it rather difficult to evaluate dendrimer effects in a mixed population of glial cells and neurons. Thus, we are at a relatively early stage of bench-to-bedside translation, and this is due mainly to the lack of data valuable for clinical investigations. It is only recently that techniques have become available that allow for analyses of biological processes inside the living cells, at the nanoscale, in real time. This review summarizes the essential properties of neural cells and dendrimers, and provides a cross-section of biological, pre-clinical and early clinical studies, where dendrimers were used as nanocarriers. It also highlights some examples of biological studies employing dendritic polyglycerol sulfates and their effects on glia and neurons. It is the aim of this review to encourage young scientists to advance mechanistic and technological approaches in dendrimer research so that these extremely versatile and attractive nanostructures gain even greater recognition in translational medicine.

Dendrimers toward Translational Nanotherapeutics: Concise Key Step Analysis

The goal of nanomedicine is to address specific clinical problems optimally, to fight human diseases, and to find clinical relevance to change clinical practice. Nanomedicine is poised to revolutionize medicine via the development of more precise diagnostic and therapeutic tools. The field of nanomedicine encompasses numerous features and therapeutic disciplines. A plethora of nanomolecular structures have been engineered and developed for therapeutic applications based on their multitasking abilities and the wide functionalization of their core scaffolds and surface groups. Within nanoparticles used for nanomedicine, dendrimers as well polymers have demonstrated strong potential as nanocarriers, therapeutic agents, and imaging contrast agents. In this review, we present and discuss the different criteria and parameters to be addressed to prepare and develop druggable nanoparticles in general and dendrimers in particular. We also describe the major requirements, included in the preclinical and clinical roadmap, for NPs/dendrimers for the preclinical stage to commercialization. Ultimately, we raise the clinical translation of new nanomedicine issues.

Targeting Mitochondria in Tumor-Associated Macrophages using a Dendrimer-Conjugated TSPO Ligand that Stimulates Antitumor Signaling in Glioblastoma

Mitochondria mediate critical cellular processes, including proliferation, apoptosis, and immune responses; as such, their dysfunction is pathogenic in many neurodegenerative disorders and cancers. In glioblastoma, targeted delivery of mitochondria-focused anticancer therapies has failed to translate into clinical success due to the nonspecific cellular localization, heterogeneity of receptor expression across patients, poor transport across biological barriers to reach the brain, tumor, and mitochondria, and systemic side effects. Strategies that can overcome brain and solid tumor barriers and selectively target mitochondria within specific cell types may lead to improvements in glioblastoma treatment. Developments in dendrimer-mediated nanomedicines have shown promise targeting tumor-associated macrophages (TAMs) in glioblastoma, following systemic administration. Here, we present a novel dendrimer conjugated to the translocator protein (18 kDa) (TSPO) ligand 5,7-dimethylpyrazolo[1,5-α]pyrimidin-3-ylacetamide (DPA). We developed a clickable DPA for conjugation on the dendrimer surface and demonstrated in vitro that the dendrimer-DPA conjugate (D-DPA) significantly increases dendrimer colocalization with mitochondria. Compared to free TSPO ligand PK11195, D-DPA stimulates greater antitumor immune signaling. In vivo, we show that D-DPA targets mitochondria specifically within TAMs following systemic administration. Our results demonstrate that dendrimers can achieve TAM-specific targeting in glioblastoma and can be further modified to target specific intracellular compartments for organelle-specific drug delivery.

Telodendrimers: Promising Architectural Polymers for Drug Delivery

Architectural complexity has played a key role in enhancing the efficacy of nanocarriers for a variety of applications, including those in the biomedical field. With the continued evolution in designing macromolecules-based nanoparticles for drug delivery, the combination approach of using important features of linear polymers with dendrimers has offered an advantageous and viable platform. Such nanostructures, which are commonly referred to as telodendrimers, are hybrids of linear polymers covalently linked with different dendrimer generations and backbones. There is considerable variety in selection from widely studied linear polymers and dendrimers, which can help tune the overall composition of the resulting hybrid structures. This review highlights the advances in articulating syntheses of these macromolecules, and the contributions these are making in facilitating therapeutic administration. Limited progress has been made in the design and synthesis of these hybrid macromolecules, and it is through an understanding of their physicochemical properties and aqueous self-assembly that one can expect to fully exploit their potential in drug delivery.