Effective Targeting of Aβ to Macrophages by Sonochemically Prepared Surface-Modified Protein Microspheres

Biodegradable Poly(trehalose) Nanoparticle for Preventing Amyloid Beta Aggregation and Related Neurotoxicity

Trehalose is a disaccharide that is capable of inhibiting protein aggregation and activating cellular autophagy. It has been shown that a polymer or nanoparticle form, terminated with multiple trehalose units, can significantly enhance the anti-amyloidogenic performance and is suitable for the treatment of neurodegenerative diseases. Here, we report a trehalose-conjugated polycarbonate-co-lactide polymer and formulation of its nanoparticles having multiple numbers of trehalose exposed on the surface. The resultant poly(trehalose) nanoparticle inhibits the aggregation of amyloid beta peptides and disintegrates matured amyloid fibrils into smaller fragments. Moreover, the poly(trehalose) nanoparticle lowers extracellular amyloid β oligomer-driven cellular stress and enhances cell viability. The presence of biodegradable polycarbonate components in the poly(trehalose) nanoparticle would enhance their application potential as an anti-amyloidogenic material.

Nanocomposites Inhibit the Formation, Mitigate the Neurotoxicity, and Facilitate the Removal of β-Amyloid Aggregates in Alzheimer's Disease Mice

Alzheimer's disease (AD) is a progressive and irreversible brain disorder. Recent studies revealed the pivotal role of β-amyloid (Aβ) in AD. However, there is no conclusive indication that the existing therapeutic strategies exerted any effect on the mitigation of Aβ-induced neurotoxicity and the elimination of Aβ aggregates simultaneously in vivo. Herein, we developed a novel nanocomposite that can eliminate toxic Aβ aggregates and mitigate Aβ-induced neurotoxicity in AD mice. This nanocomposite was designed to be a small-sized particle (14 ± 4 nm) with Aβ-binding peptides (KLVFF) integrated on the surface. The nanocomposite was prepared by wrapping a protein molecule with a cross-linked KLVFF-containing polymer layer synthesized by in situ polymerization. The presence of the nanocomposite remarkably changed the morphology of Aβ aggregates, which led to the formation of Aβ/nanocomposite coassembled nanoclusters instead of Aβ oligomers. With the reduction of the pathological Aβ oligomers, the nanocomposites attenuated the Aβ-induced neuron damages, regained endocranial microglia's capability to phagocytose Aβ, and eventually protected hippocampal neurons against apoptosis. Thus, we anticipate that the small-sized nanocomposite will potentially offer a feasible strategy in the development of novel AD treatments.

Controlling Molecular Weight of Hyaluronic Acid Conjugated on Amine-rich Surface: Toward Better Multifunctional Biomaterials for Cardiovascular Implants

The molecular weights (MWs) of hyaluronic acid (HA) in extracellular matrix secreted from both vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) play crucial roles in the cardiovascular physiology, as HA with appropriate MW influences important pathways of cardiovascular homeostasis, inhibits VSMC synthetic phenotype change and proliferation, inhibits platelet activation and aggregation, promotes endothelial monolayer repair and functionalization, and prevents inflammation and atherosclerosis. In this study, HA samples with gradients of MW (4 × 10³, 1 × 10⁵, and 5 × 10⁵ Da) were prepared by covalent conjugation to a copolymerized film of polydopamine and hexamethylendiamine (PDA/HD) as multifunctional coatings (PDA/HD-HA) with potential to improve the biocompatibility of cardiovascular biomaterials. The coatings immobilized with high-MW-HA (PDA/HD-HA-2: 1 × 10⁵ Da; PDA/HD-HA-3: 5 × 10⁵ Da) exhibited a remarkable suppression of platelet activation/aggregation and thrombosis under 15 dyn/cm² blood flow and simultaneously suppressed the adhesion and proliferation of VSMC and the adhesion, activation, and inflammatory cytokine release of macrophages. In particular, PDA/HD-HA-2 significantly enhanced VEC adhesion, proliferation, migration, and functional factors release, as well as the captured number of endothelial progenitor cells under dynamic condition. The in vivo results indicated that the multifunctional surface (PDA/HD-HA-2) created a favorable microenvironment of endothelial monolayer formation and functionalization for promoting reendothelialization and reducing restenosis of cardiovascular biomaterials.

Strong multi-functions based on conjugating chondroitin sulfate onto an amine-rich surface will direct the vascular cell fate for cardiovascular implanted devices

This research may support potential applications for surface modification of cardiovascular implants to achieve improved multi-functions.

Specifically targeted delivery of protein to phagocytic macrophages

Macrophages play important roles in the pathogenesis of various diseases, and are important potential therapeutic targets. Furthermore, macrophages are key antigen-presenting cells and important in vaccine design. In this study, we report on the novel formulation (bovine serum albumin [BSA]-loaded glucan particles [GMP-BSA]) based on β-glucan particles from cell walls of baker’s yeast for the targeted delivery of protein to macrophages. Using this formulation, chitosan, tripolyphosphate, and alginate were used to fabricate colloidal particles with the model protein BSA via electrostatic interactions, which were caged and incorporated BSA very tightly within the β-glucan particle shells. The prepared GMP-BSA exhibited good protein-release behavior and avoided protein leakage. The particles were also highly specific to phagocytic macrophages, such as Raw 264.7 cells, primary bone marrow-derived macrophages, and peritoneal exudate macrophages, whereas the particles were not taken up by nonphagocytic cells, including NIH3T3, AD293, HeLa, and Caco-2. We hypothesize that these tightly encapsulated protein-loaded glucan particles deliver various types of proteins to macrophages with notably high selectivity, and may have broad applications in targeted drug delivery or vaccine design against macrophages.

(Lipo)polysaccharide interactions of antimicrobial peptides

Due to rapidly increasing resistance development against conventional antibiotics, as well as problems associated with diseases either triggered or deteriorated by infection, antimicrobial and anti-inflammatory peptides have attracted considerable interest during the last few years. While there is an emerging understanding of the direct antimicrobial function of such peptides through bacterial membrane destabilization, the mechanisms of their anti-inflammatory function are less clear. We here summarize some recent results obtained from our own research on anti-inflammatory peptides, with focus on peptide-(lipo)polysaccharide interactions.

Insight into the inhibition effect of acidulated serum albumin on amyloid β-protein fibrillogenesis and cytotoxicity

Alzheimer's disease (AD) is the most prevalent form of dementia, and aggregation of amyloid β-proteins (Aβ) into soluble oligomers and fibrils has been implicated in the pathogenesis of AD. Herein we developed acidulated serum albumin for the inhibition of Aβ42 fibrillogenesis. Bovine serum albumin (BSA) was modified with diglycolic anhydride, leading to the coupling of 14.5 more negative charges (carboxyl groups) on average on each protein surface. The acidulated BSA (A-BSA) was characterized and confirmed to keep the tertiary structure and stability of BSA. Extensive biophysical and biological analyses showed that A-BSA significantly inhibited Aβ42 fibrillogenesis and mitigated amyloid cytotoxicity. As compared to the Aβ42-treated group (cell viability, 50%), the cell viability increased to 88% by the addition of equimolar A-BSA. The inhibitory effect was remarkably higher than that of BSA at the same concentration. On the basis of the experimental findings, a mechanistic model was proposed. The model considers that Aβ42 is bound to the A-BSA surface by hydrophobic interactions, but the widely distributed negative charges on the A-BSA surface give rise to electrostatic repulsions to the bound Aβ42 that is also negatively charged. The two well-balanced opposite forces make Aβ42 adopt extended conformations instead of the β-sheet structure that is necessary for the on-pathway fibrillogenesis, even when the protein is released off the surface. Thus, A-BSA greatly slows down the fibrillation and changes the fibrillogenesis pathway, leading to the formation of less toxic aggregates. The findings and the mechanistic model offer new insights into the development of more potent inhibitors of Aβ fibrillogenesis and cytotoxicity.