Toll-like receptor 4 agonist-based nanoparticles orchestrate protection against sepsis

Sepsis, a life-threatening organ dysfunction induced by severe infection and uncontrolled host immune response, threatens the health of people all over the world. Herein, a type of nanoparticle formulation with simple components is synthesized by encapsulating monophosphoryl lipid A (MPLA), a TLR4 agonist, with poly(lactic-co-glycolic acid) (PLGA) nanoparticle. The obtained nanoparticles (MPLA@PLGA) could provide Escherichia coli (E. coli)-induced sepsis protection by regulating the immune system after sepsis challenge, including promoting the levels of various cytokines, boosting the percentage of natural killer cells and accelerating bacterial clearance. Notably, the survival mice pre-treated with these nanoparticles could resist repeated E. coli-induced sepsis. Our work therefore provides the great promise of MPLA@PLGA nanoparticles as a simple yet effective nano-drug for prevention and protection against E. coli-induced sepsis.

Designing a Cleavable Cell Surface Protein for Cytotherapy and Drug Delivery Applications

Many cytotherapy applications focus on delivering a therapeutic molecule or nanoparticle to a disease site. One challenging step in this delivery is releasing the therapeutic molecule from the delivery cell upon arrival at the delivery sight. Here a protein is designed and expressed that can bind a biotin-labeled cargo and release that cargo in response to the presence of urokinase plasminogen activator. A gene was designed that coded for a protein that contained a streptavidin domain for binding biotin-labeled cargo, a urokinase cleavage domain for release by urokinase plasminogen activator, and a PLAP domain for cell-surface expression. The utility of the resultant protein was tested with biotin (5-fluorescein) and a biotinylated PLGA nanoparticle to test the performance of the delivery systems with models for small molecule drugs and nanoformulations. When expressed in neural progenitor cells (C17.2), the designed protein was able to bind both the biotin (5-fluorescein) and the biotinylated PLGA nanoparticles and was able to release the biotin (5-fluorescein) in response to urokinase plasminogen activator. This designed, multi-domain protein may prove useful as a method for specifically releasing a cargo from delivery cells at a target site.

Development of a chitosan‐modified PLGA nanoparticle vaccine for protection against Escherichia coli K1 caused meningitis in mice

Background Escherichia coli K1 (E. coli K1) caused neonatal meningitis remains a problem, which rises the urgent need for an effective vaccine. Previously, we rationally designed and produced the recombinant protein OmpAVac (Vo), which elicited protective immunity against E. coli K1 infection. However, Vo has limited stability, which hinders its future industrial application. Method Chitosan-modified poly (lactic-co-glycolic acid) (PLGA) nanoparticles were prepared and used as carried for the recombinant Vo. And the safety, stability and immunogenicity of Vo delivered by chitosan-modified PLGA nanoparticles were tested in vitro and in a mouse model of bacteremia. Results We successfully generated chitosan-modified PLGA nanoparticles for the delivery of recombinant Vo (VoNP). In addition, we found that a freeze-drying procedure increases the stability of the VoNPs without changing the shape, size distribution and encapsulation of the Vo protein. Unlike aluminum adjuvant, the nanoparticles that delivered Vo were immunoprotective in mice even after storage for as long as 180 days. Conclusions We identified an effective strategy to improve the stability of Vo to maintain its immunogenicity, which will contribute to the future development of vaccines against E. coli K1.

Doxorubicin Loaded PLGA Nanoparticle with Cationic/Anionic Polyelectrolyte Decoration: Characterization, and Its Therapeutic Potency

Optimized Doxorubicin hydrochloride (DOX) loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (DPN) were prepared by controlling the water/oil distribution of DOX at different pH solutions and controlling the electrostatic interaction between DOX and different terminated-end PLGAs. Furthermore, cationic polyethylenimine (PEI) and anionic poly (acrylic acid) (PAA) were alternately deposited on DPN surface to form PEI-DPN (IDPN) and PAA-PEI-DPN (AIDPN) to enhance cancer therapy potency. Compared to DPN, IDPN exhibited a slower release rate in physiological conditions but PEI was demonstrated to increase the efficiency of cellular uptake and endo/lysosomal escape ability. AIDPN, with the outermost negatively charged PAA layer, still retained better endo/lysosomal escape ability compared to DPN. In addition, AIDPN exhibited the best pH-dependent release profile with 1.6 times higher drug release in pH 5.5 than in pH 7.4. Therefore, AIDPN with the characteristics of PEI and PAA simultaneously was the most optional cancer therapy choice within these three PLGA nanoparticles. As the proposed nanoparticles integrated optimal procedure factors, and possessed cationic and anionic outlayer, our drug delivery nanoparticles can provide an alternative solution to current drug delivery technologies.