In Vivo Insulin Peptide Autoantigen Delivery by Mannosylated Sodium Alginate Nanoparticles Delayed but Could Not Prevent the Onset of Type 1 Diabetes in Nonobese Diabetic Mice.

Type 1 diabetes (T1D) is an autoimmune subtype of diabetes, mainly caused by the immune attack of self-insulin-producing cells. Immune modulation that delays the onset of T1D is able to reduce diabetic complications and mortality. We have previously reported that mannosylated sodium alginate nanoparticles (MAN-ALG) exhibited excellent dendritic cell targeting and in vivo antigen delivery efficacy. To investigate the role of MAN-ALG in an autoimmune context, we loaded the MAN-ALG with Ins29-23, a T1D autoantigen [MAN-ALG(PEP)], for T1D immune tolerance induction in nonobese diabetic (NOD) mice. We observed the delayed onset of T1D occurrence and some degree of blood glucose reduction accompanied by a larger islet area, attributable to augmented T-regulatory cell proportion in mice treated with MAN-ALG(PEP). However, MAN-ALG was also found to elicit lysosomal escape and cross-presentation of Ins29-23 in bone marrow-derived dendritic cells, leading to the immune activation of Ins29-23-recognizing T cells and destruction of Ins29-23-expressing islet cells. This dual impact resulted in delayed but a nonpreventive effect of MAN-ALG(PEP) on the T1D onset in NOD mice. Considering the potent immune stimulatory property of MAN-ALG, cautions should be implemented when using alginate-based biomaterials in an autoimmune context. Moreover, it is also noted that regarding the in vivo outcome of immune therapies, biomaterial-based delivery systems and their detailed role on immune regulation need to be examined.

Old Dog New Tricks: PLGA Microparticles as an Adjuvant for Insulin Peptide Fragment-Induced Immune Tolerance against Type 1 Diabetes.

Poly[lactic-co-(glycolic acid)] (PLGA) is arguably one of the most versatile synthetic copolymers used for biomedical applications. In vivo delivery of multiple substances including cells, pharmaceutical compounds, and antigens has been achieved by using PLGA-based micro-/nanoparticles although, presently, the exact biological impact of PLGA particles on the immune system remains controversial. Type 1 diabetes (T1D) is one subtype of diabetes characterized by the attack of immune cells against self-insulin-producing pancreatic islet cells. Considering the autoimmune etiology of T1D and the recent use of PLGA particles for eliciting desired immune responses in various aspects of immunotherapy, for the present study, a combination of Ins29-23 peptide (a known autoantigen of T1D) and PLGA microparticles was selected for T1D prevention assessment in nonobese diabetic (NOD) mice, a well-known animal model with spontaneous development of T1D. Thus, inoculation of PLGA microparticles + Ins29-23 completely prevented T1D development, significantly better than untreated controls and mice treated by either PLGA microparticles or Ins29-23 per se. Subsequent mechanistic investigation further revealed a facilitative role of PLGA microparticles in immune tolerance induction. In summary, our data demonstrate an adjuvant potential of PLGA microparticles in tolerance induction and immune remodulation for effective prevention of autoimmune diseases such as T1D.

Nanoparticles with CD44 Targeting and ROS Triggering Properties as Effective in Vivo Antigen Delivery System.

Currently, development of subunit vaccine based on recombinant antigens or peptides has gradually become an important alternative option for traditional vaccine. However, induction of potent immune response with desired efficacy remains a major challenge. The nanoparticle-based antigen delivery system has been considered a potential carrier system to improve the efficacy of subunit vaccine. In the present study, we have designed an immune-stimulatory delivery system by conjugating three-armed PLGA to PEG via the peroxalate ester bond which is sensitive to hydrogen peroxide (H2O2), a major reactive oxygen species (ROS). Hyaluronic acid (HA), a ligand for CD44 receptors was also modified onto the outer shell of the 3s-PLGA-PEG nanoparticles to promote immune cell uptake. For in vitro and in vivo immune response assessment, a model antigen ovalbumin (OVA) was enclosed within the core of the 3s-PLGA-PEG nanoparticles to form 3s-PLGA-PO-PEG/HA nanoparticles (PHO NPs). Our results showed that the PHO NPs enhanced dendritic cell maturation, antigen uptake, and antigen presentation in vitro, likely due to enhanced lysosomal escape. In vivo experiments further revealed that the PHO nanovaccine robustly promoted OVA-specific antibody production and T cell response accompanied by modest stimulation of memory T cells. In summary, the ROS-responsive PHO NPs with modified HA may be an effective vehicle antigen delivery system to promote antigen-induced immune response.

Dual functionalization of poly(ε-caprolactone) film surface through supramolecular assembly with the aim of promoting in situ endothelial progenitor cell attachment on vascular grafts.

In this study, we developed a method for the dual functionalization of a poly(ε-caprolactone) (PCL) surface by means of the supramolecular assembly technology. Polyethylene glycol (PEG), with resistance to protein adsorption, and TPSLEQRTVYAK (TPS) peptide, which can specifically bind endothelial progenitor cells (EPCs), were immobilized on the PCL surface through host-guest inclusion complexation. The chemical composition as well as the hydrophilic/hydrophobic property of the functionalized surface was characterized by X-ray photoelectron spectroscopy and water contact angle measurements. The relative composition of two functional molecules on the dually functionalized surface was further analyzed by fluorescence quantification. Finally, the fibrinogen adsorption, platelet adhesion and activation, and selective attachment of cells were systematically evaluated on the functionalized surface. The results show that the presence of PEG evidently inhibited the adsorption of plasma protein and platelet adhesion, thus reducing the possibility of thrombus formation on the functionalized surface. At the same time, the TPS-functionalized surface demonstrated enhanced attachment toward EPC compared with the surfaces in the absence of TPS functionalization. For the surface functionalized by both PEG and TPS, the functions provided by each component have been well demonstrated. The relative composition of the PEG and TPS could be further fine-tuned by adjusting the feeding ratio. All these results indicate that the dually functionalized surface developed in this study is a suitable candidate for vascular graft to induce and promote in situ endothelialization.

Highly sensitive H2O2-scavenging nano-bionic system for precise treatment of atherosclerosis.

In atherosclerosis, chronic inflammatory processes in local diseased areas may lead to the accumulation of reactive oxygen species (ROS). In this study, we devised a highly sensitive H2O2-scavenging nano-bionic system loaded with probucol (RPP-PU), to treat atherosclerosis more effectively. The RPP material had high sensitivity to H2O2, and the response sensitivity could be reduced from 40 to 10 µmol/L which was close to the lowest concentration of H2O2 levels of the pathological environment. RPP-PU delayed the release and prolonged the duration of PU in vivo. In Apolipoprotein E deficient (ApoE‒/‒) mice, RPP-PU effectively eliminated pathological ROS, reduced the level of lipids and related metabolic enzymes, and significantly decreased the area of vascular plaques and fibers. Our study demonstrated that the H2O2-scavenging nano-bionic system could scavenge the abundant ROS in the atherosclerosis lesion, thereby reducing the oxidative stress for treating atherosclerosis and thus achieve the therapeutic goals with atherosclerosis more desirably.

Significant difference between sirolimus and paclitaxel nanoparticles in anti-proliferation effect in normoxia and hypoxia: The basis of better selection of atherosclerosis treatment.

Compared with paclitaxel, sirolimus has been more used in the treatment of vascular restenosis gradually as an anti-proliferative drug, but few basic studies have elucidated its mechanism. The anti-proliferative effects of sirolimus or paclitaxel have been demonstrated by numerous studies under normoxia, but few studies have been achieved focusing hypoxia. In this study, porcine carotid artery injury model and classical cobalt chloride hypoxia cell model were established. Sirolimus nanoparticles (SRM-NPs), paclitaxel nanoparticles (PTX-NPs) and blank nanoparticles (Blank-NPs) were prepared respectively. The effect of RPM-NPs on the degree of stenosis, proliferative index and the expression of PCNA after 28 days of porcine carotid artery injury model was evaluated. Compared with saline group and SRM groups, SRM-NPs group suppressed vascular stenosis, proliferative index and the expression of PCNA (P < 0.01 and P < 0.05). Endothelial cell (EC) and smooth muscle cell (SMC) were pre-treated with cobaltous chloride, followed by SRM-NPs, PTX-NPs, Blank-NPs or PBS control treating, the effects on cell proliferation, HIF-1 expression and glycolysis were detected. SRM-NPs could inhibit EC and SMC proliferation under hypoxia, while PTX-NPs couldn't (P < 0.001). Significant differences between sirolimus and paclitaxel NPs in anti-proliferation effect under normoxia and hypoxia may due to the different inhibitory effects on HIF-1α expression and glycolysis. In conclusion, these results suggest that sirolimus can inhibit the proliferation of hypoxic cells more effectively than paclitaxel. These observations may provide a basis for understanding clinical vascular stenosis therapeutic differences between rapamycin and paclitaxel.

Silk fibroin-coated PLGA dimpled microspheres for retarded release of simvastatin.

The surface physical features and chemical components of polymeric particles play an important role in drug delivery systems. In this study, PLGA blank microspheres and simvastatin-loaded PLGA microspheres with dimpled surface structure were prepared by single emulsion-solvent evaporation method in the absence of any additives. Subsequently, glutaraldehyde cross-linking was optimized for silk fibroin coating on simvastatin-loaded PLGA dimpled microspheres due to good solubility of simvastatin in alcohol. Furthermore, simvastatin release kinetics was investigated for silk-coated or plain PLGA dimpled microspheres. These drug carriers may have potential applications for alveolar ridge preservation with local delivery of simvastatin.

Mechanism and In Vivo Evaluation: Photodynamic Antibacterial Chemotherapy of Lysine-Porphyrin Conjugate.

Lysine-porphyrin conjugate 4i has potent photosensitive antibacterial effect on clinical isolated bacterial strains such as Methicillin-resistant Staphylococcus aureus (MRSA), Escherichia coli, and Pseudomonas aeruginosa. The mechanism of photodynamic antibacterial chemotherapy of 4i (4i-PACT) in vitro and the treatment effect in vivo was investigated in this paper. Atomic force microscopy (AFM) revealed that 4i-PACT can effectively destroy membrane and wall of bacteria, resulting in leakage of its content. This was confirmed by dual fluorescent staining with acridine orange/ethidium bromide and measuring materials absorption at 260 nm. Agarose gel electrophoresis measurement showed that 4i-PACT can damage genomic DNA. Healing of wound in rat infected by mixed bacteria showed that the efficiency of 4i-PACT is dependent on the dose of light. These results showed that 4i-PACT has promising bactericidal effect both in vitro and in vivo.

Hydrogen peroxide-responsive micelles self-assembled from a peroxalate ester-containing triblock copolymer.

A novel ABA triblock copolymer by using peroxalate esters as linkages was synthesized. In water, this amphiphilic copolymer self-assembled into micelles which were used as drug delivery carriers. When stimulated with hydrogen peroxide, the micelles disassembled to release drugs since the responsive peroxalate ester linkages would be cleaved after the reaction with hydrogen peroxide.