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1. Drug Delivery to the Brain across the Blood–Brain Barrier Using Nanomaterials

   https://doi.org/10.1002/smll.201701921  

   Tsou, Yung‐Hao; Zhang, Xue‐Qing; Zhu, He; Syed, Sahla; Xu, Xiaoyang (October 2017, Small)

   Abstract A major obstacle facing brain diseases such as Alzheimer's disease, multiple sclerosis, brain tumors, and strokes is the blood–brain barrier (BBB). The BBB prevents the passage of certain molecules and pathogens from the circulatory system into the brain. Therefore, it is nearly impossible for therapeutic drugs to target the diseased cells without the assistance of carriers. Nanotechnology is an area of growing public interest; nanocarriers, such as polymer‐based, lipid‐based, and inorganic‐based nanoparticles can be engineered in different sizes, shapes, and surface charges, and they can be modified with functional groups to enhance their penetration and targeting capabilities. Hence, understanding the interaction between nanomaterials and the BBB is crucial. In this Review, the components and properties of the BBB are revisited and the types of nanocarriers that are most commonly used for brain drug delivery are discussed. The properties of the nanocarriers and the factors that affect drug delivery across the BBB are elaborated upon in this review. Additionally, the most recent developments of nanoformulations and nonconventional drug delivery strategies are highlighted. Finally, challenges and considerations for the development of brain targeting nanomedicines are discussed. The overall objective is to broaden the understanding of the design and to develop nanomedicines for the treatment of brain diseases. 

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2. COVID-19 vaccines based on viral nanoparticles displaying a conserved B-cell epitope show potent immunogenicity and a long-lasting antibody response

   https://doi.org/10.3389/fmicb.2023.1117494  

   Affonso de Oliveira, Jessica Fernanda; Zhao, Zhongchao; Xiang, Yi; Shin, Matthew D.; Villaseñor, Kathleen Elizabeth; Deng, Xinyi; Shukla, Sourabh; Chen, Shaochen; Steinmetz, Nicole F. (April 2023, Frontiers in Microbiology)

   The COVID-19 pandemic caused by SARS-CoV-2 sparked intensive research into the development of effective vaccines, 50 of which have been approved thus far, including the novel mRNA-based vaccines developed by Pfizer and Moderna. Although limiting the severity of the disease, the mRNA-based vaccines presented drawbacks, such as the cold chain requirement. Moreover, antibody levels generated by these vaccines decline significantly after 6 months. These vaccines deliver mRNA encoding the full-length spike (S) glycoprotein of SARS-CoV-2, but must be updated as new strains and variants of concern emerge, creating a demand for adjusted formulations and booster campaigns. To overcome these challenges, we have developed COVID-19 vaccine candidates based on the highly conserved SARS CoV-2, 809-826 B-cell peptide epitope (denoted 826) conjugated to cowpea mosaic virus (CPMV) nanoparticles and bacteriophage Qβ virus-like particles, both platforms have exceptional thermal stability and facilitate epitope delivery with inbuilt adjuvant activity. We evaluated two administration methods: subcutaneous injection and an implantable polymeric scaffold. Mice received a prime–boost regimen of 100 μg per dose (2 weeks apart) or a single dose of 200 μg administered as a liquid formulation, or a polymer implant. Antibody titers were evaluated longitudinally over 50 weeks. The vaccine candidates generally elicited an early Th2-biased immune response, which stimulates the production of SARS-CoV-2 neutralizing antibodies, followed by a switch to a Th1-biased response for most formulations. Exceptionally, vaccine candidate 826-CPMV (administered as prime-boost, soluble injection) elicited a balanced Th1/Th2 immune response, which is necessary to prevent pulmonary immunopathology associated with Th2 bias extremes. While the Qβ-based vaccine elicited overall higher antibody titers, the CPMV-induced antibodies had higher avidity. Regardless of the administration route and formulation, our vaccine candidates maintained high antibody titers for more than 50 weeks, confirming a potent and durable immune response against SARS-CoV-2 even after a single dose. 

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3. Mapping of antibody epitopes based on docking and homology modeling

   https://doi.org/10.1002/prot.26420  

   Desta, Israel T.; Kotelnikov, Sergei; Jones, George; Ghani, Usman; Abyzov, Mikhail; Kholodov, Yaroslav; Standley, Daron M.; Sabitova, Maria; Beglov, Dmitri; Vajda, Sandor; et al (September 2022, Proteins: Structure, Function, and Bioinformatics)

   Abstract Antibodies are key proteins produced by the immune system to target pathogen proteins termed antigens via specific binding to surface regions called epitopes. Given an antigen and the sequence of an antibody the knowledge of the epitope is critical for the discovery and development of antibody based therapeutics. In this work, we present a computational protocol that uses template‐based modeling and docking to predict epitope residues. This protocol is implemented in three major steps. First, a template‐based modeling approach is used to build the antibody structures. We tested several options, including generation of models using AlphaFold2. Second, each antibody model is docked to the antigen using the fast Fourier transform (FFT) based docking program PIPER. Attention is given to optimally selecting the docking energy parameters depending on the input data. In particular, the van der Waals energy terms are reduced for modeled antibodies relative to x‐ray structures. Finally, ranking of antigen surface residues is produced. The ranking relies on the docking results, that is, how often the residue appears in the docking poses' interface, and also on the energy favorability of the docking pose in question. The method, called PIPER‐Map, has been tested on a widely used antibody–antigen docking benchmark. The results show that PIPER‐Map improves upon the existing epitope prediction methods. An interesting observation is that epitope prediction accuracy starting from antibody sequence alone does not significantly differ from that of starting from unbound (i.e., separately crystallized) antibody structure. 

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4. Intracellular Antibody Delivery Mediated by Lipids, Polymers, and Inorganic Nanomaterials for Therapeutic Applications

   https://doi.org/10.1002/adtp.202000178  

   Li, Yamin; Li, Peixuan; Li, Raissa; Xu, Qiaobing (September 2020, Advanced Therapeutics)

   Abstract Therapeutic antibodies, due to their high affinity and specificity toward their biological targets, may demonstrate reduced harmful side effects compared with traditional drug moieties. While most of the as‐yet clinically approved antibody therapeutics have targeted extracellular or membrane‐bound domains, the ability to target intracellular antigens with antibodies opens up tremendous opportunities for imaging, diagnosis, and therapeutic applications. Generally, delivery concerns have limited the ability to target intracellular antigens, as many antibodies cannot easily cross the cell membrane due to their size and surface chemistry. Delivery platforms have been explored to address this issue, including physical methods, fusion protein/peptide techniques, and synthetic carrier‐based systems. This review summarizes the progress of carrier‐based intracellular antibody delivery systems employing synthetic lipids, polymers, and inorganic nanomaterials. Antibodies targeting various epitopes have been loaded through adsorption, conjugation, or physical encapsulation strategies. Successful intracellular deliveries have been demonstrated largely through fluorescence imaging using dye‐labeled antibody cargos. Specific synthetic delivery platforms have great potential for ex vivo and in vivo therapeutic applications. Challenges and opportunities are further discussed for material scientists to explore in this research area. 

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5. Dynamic 3D On-Chip BBB Model Design, Development, and Applications in Neurological Diseases

   https://doi.org/10.3390/cells10113183  

   Chen, Xingchi; Liu, Chang; Muok, Laureana; Zeng, Changchun; Li, Yan (November 2021, Cells)

   The blood–brain barrier (BBB) is a vital structure for maintaining homeostasis between the blood and the brain in the central nervous system (CNS). Biomolecule exchange, ion balance, nutrition delivery, and toxic molecule prevention rely on the normal function of the BBB. The dysfunction and the dysregulation of the BBB leads to the progression of neurological disorders and neurodegeneration. Therefore, in vitro BBB models can facilitate the investigation for proper therapies. As the demand increases, it is urgent to develop a more efficient and more physiologically relevant BBB model. In this review, the development of the microfluidics platform for the applications in neuroscience is summarized. This article focuses on the characterizations of in vitro BBB models derived from human stem cells and discusses the development of various types of in vitro models. The microfluidics-based system and BBB-on-chip models should provide a better platform for high-throughput drug-screening and targeted delivery. 

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