Immune responses in mice of beta-galactosidase adsorbed or encapsulated in poly(lactic acid) and poly(lactic-co-glycolic acid) microspheres

Recent Advances in the Development of Biomimetic Materials

In this review, we focused on recent efforts in the design and development of materials with biomimetic properties. Innovative methods promise to emulate cell microenvironments and tissue functions, but many aspects regarding cellular communication, motility, and responsiveness remain to be explained. We photographed the state-of-the-art advancements in biomimetics, and discussed the complexity of a "bottom-up" artificial construction of living systems, with particular highlights on hydrogels, collagen-based composites, surface modifications, and three-dimensional (3D) bioprinting applications. Fast-paced 3D printing and artificial intelligence, nevertheless, collide with reality: How difficult can it be to build reproducible biomimetic materials at a real scale in line with the complexity of living systems? Nowadays, science is in urgent need of bioengineering technologies for the practical use of bioinspired and biomimetics for medicine and clinics.

Tackling autoimmunity with nanomedicines

Tolerogenic immunotherapy aims to blunt pathogenic inflammation without affecting systemic immunity. However, the anti-inflammatory drugs and immunosuppressive biologics that are used in the clinic usually result in nonspecific immune cell suppression and off-target toxicity. For this reason, strategies have been developed to induce antigen-specific immune tolerance through the delivery of disease-relevant antigens by nanocarriers as a benefit of their preferential internalization by antigen-presenting cells. Herein, we discuss the recent advances in the nanotechnology-based antigen-specific tolerance approaches. Some of these designs are based on nanoparticles delivering antigens and immunoregulatory agents to modulate antigen-presenting pathways, while others directly target T cells via nanoparticle-based artificial antigen-presenting cells. These antigen-specific therapies are hoped to replace systemic immune suppression and provide long-term disease remission.

Design of biodegradable nanoparticles to modulate phenotypes of antigen-presenting cells for antigen-specific treatment of autoimmune disease

Current therapeutic options for autoimmune diseases, such as multiple sclerosis (MS), often require lifelong treatment with immunosuppressive drugs, yet strategies for antigen-specific immunomodulation are emerging. Biodegradable particles loaded with disease-specific antigen, either alone or with immunomodulators, have been reported to ameliorate disease. Herein, we hypothesized that the carrier could impact polarization of the immune cells that associate with particles and the subsequent disease progression. Single injection of three polymeric carriers, 50:50 poly (DL-lactide-co-glycolide) (PLG) with two molecular weights (Low, High) and poly (DL-lactide) (PLA), loaded with the disease-specific antigen, proteolipid protein (PLP_139-151), were investigated for the ability to attenuate clinical scores in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. At a low particle dose, mice treated with PLA-based particles had significantly lower clinical scores at the chronic stage of the disease over 200 days post immunization, while neither PLG-based particles nor OVA control particles reduced the clinical scores. Compared to PLG-based particles, PLA-based particles were largely associated with Kupffer cells and liver sinusoidal endothelial cells, which had a reduced co-stimulatory molecule expression that correlated with a reduction of CD4⁺ T-cell populations in the central nervous system. Delivery of PLA-based particles encapsulated with higher levels of PLP_139-151 at a reduced dose were able to completely ameliorate EAE over 200 days along with inhibition of Th1 and Th17 polarization. Collectively, our study demonstrates that the carrier properties and antigen loading determine phenotypes of immune cells in the peripheral organs, influencing the amelioration of both acute and chronic stages of autoimmunity.

Magnetic nanoparticles for tumor imaging and therapy: a so-called theranostic system

In this review, we discussed the establishment of a so-called "theranostic" system by instituting the basic principles including the use of: [1] magnetic iron oxide nanoparticles (MION)-based drug carrier; [2] intra-arterial (I.A.) magnetic targeting; [3] macromolecular drugs with unmatched therapeutic potency and a repetitive reaction mechanism; [4] cell-penetrating peptide-mediated cellular drug uptake; and [5] heparin/protamine-regulated prodrug protection and tumor-specific drug re-activation into one single drug delivery system to overcome all possible obstacles, thereby achieving a potentially non-invasive, magnetic resonance imaging-guided, clinically enabled yet minimally toxic brain tumor drug therapy. By applying a topography-optimized I.A. magnetic targeting to dodge rapid organ clearance of the carrier during its first passage into the circulation, tumor capture of MION was enriched by >350 folds over that by conventional passive enhanced permeability and retention targeting. By adopting the prodrug strategy, we observed by far the first experimental success in a rat model of delivering micro-gram quantity of the large β-galactosidase model protein selectively into a brain tumor but not to the ipsi- or contra-lateral normal brain regions. With the therapeutic regimens of most toxin/siRNA drugs to fully (>99.9%) eradicate a tumor being in the nano-molar range, the prospects of reaching this threshold become practically accomplishable.

Sufficiency of a single administration of filarial antigens adsorbed on polymeric lamellar substrate particles of poly (L-lactide) for immunization

A majority of antigens require repeated administration to ensure development of adequate humoral and cell mediated immune response. To minimize the number of administrations required, we investigated the utility of biodegradable polymeric lamellar substrate particles of poly (l-lactide) (PLSP) as adjuvant for filarial antigen preparations. PLSP was prepared and characterized and Brugia malayi adult worm extract (BmA) and its SDS-PAGE resolved 54-68 kDa fraction F6 were adsorbed on to PLSP. Swiss mice received a single injection of PLSP-F6, PLSP-BmA, FCA-F6, FCA-BmA and two doses of the plain antigens. Specific IgG, IgG1, IgG2a, IgG2b and IgE levels in serum, IFN-γ, TNF-α and nitric oxide (NO) release from cells of the immunized animals in response to antigen challenge were studied. The average size of PLSP particles was <10 μm and its % antigen adsorption efficacy was 60.4, 55.2 and 61.6 for BSA, BmA and F6, respectively. Single injection of PLSP-F6 or PLSP-BmA produced better immune responses compared to one injection of FCA-F6/BmA or two injections of plain F6 or BmA. Moreover, PLSP-F6 produced much better response than PLSP-BmA. These data demonstrate for the first time that PLSP is a superior immunoadjuvant for enhancing the immune response to filarial BmA and F6 molecules and obviates the need for multiple immunization injections.

Targeted lung cancer therapy using ephrinA1-loaded albumin microspheres

OBJECTIVES

EphrinA1, the ligand of EphA2 receptor tyrosine kinase, has been proven to suppress the growth of tumours. The aim of this study was to conjugate ephrinA1 on the surface of albumin microspheres and investigate the non-small cell lung carcinoma growth and migration in vitro.

METHODS

Bovine serum albumin microspheres were designed and synthesized using a natural polymer albumin by emulsification chemical cross-linking. EphrinA1 was then conjugated on the surface of microspheres by imine formation. The microspheres conjugated with ephrinA1 (ephrinA1-MS) were characterized for particle size, surface morphology, loading efficiency and stability in vitro. The ephrinA1-MS were labelled with fluorescein isothiocyanate to determine phagocytosis. In addition, the effects of ephrinA1-MS on A549 cell growth and migration were determined.

KEY FINDINGS

Albumin microspheres exhibited low toxicity for A549 cells (above 90% cell viability). More than 80% of microspheres were phagocytosed within 2 h of incubation. EphrinA1-MS decreased the expression of focal adhesion kinase more effectively than recombinant ephrinA1 alone. Furthermore, ephrinA1-MS showed significant inhibition of non-small cell lung cancer migration when compared with resting cells. EphrinA1-MS attenuated the growth of tumour colonies in matrigels.

CONCLUSIONS

The developed ephrinA1-MS may serve as potential carriers for targeted delivery of the tumour suppressive protein ephrinA1, with minimal cytotoxic effects and greater antitumour therapeutic efficacy against non-small cell lung cancer.

Magnetically-enabled and MR-monitored selective brain tumor protein delivery in rats via magnetic nanocarriers

The delivery of bioactive proteins to tumors is associated with many difficulties that have impeded clinical translation of these promising therapeutics. Herein we present an approach, including (1) use of magnetically-responsive and MRI-visible nanoparticles as drug carriers, (2) topography-optimized intra-arterial magnetic targeting, (3) MRI-guided subject alignment within the magnetic field, and (4) surface modification of the protein drug with membrane-permeable polyethyleneimine (PEI), to prevail over the obstacles in protein delivery. Applying these methodologies, we demonstrated the delivery of a significant quantity of β-galactosidase selectively into brain tumors of glioma-bearing rats, while limiting the exposure of normal brain regions. Clinical viability of the technologies utilized, and the ability to deliver proteins at high nanomolar-range tumor concentrations, sufficient to completely eradicate a tumor lesion with existing picomolar-potency protein toxins, renders the prospect of enabling protein-based cancer therapy extremely promising.

Comparative characterization of cultures of primary human macrophages or dendritic cells relevant to biomaterial studies

Macrophages are central mediators of biomaterial-associated wound healing. Dendritic cells (DCs) link innate and adaptive immunity and are important in the context of the host response to combination products. Starting with human peripheral blood mononuclear cells (PBMCs), DCs were derived from monocytes upon culture with granulocyte macrophage colony-stimulating factor and interleukin-4; macrophages were derived from monocytes upon culture without cytokines. Macrophage or DC cultures were characterized at relevant timepoints in both adherent and nonadherent fractions on control Primaria surfaces to characterize and define these inflammatory/immune cells as a prequel to their use in in vitro test biomaterial-host response studies. At day 10 (typical time for harvesting macrophages for subsequent treatment with test biomaterials), macrophages were CD11c+, macrophage mannose receptor (MMR)+, CD14+, and CD64+. At day 6 (typical time for harvesting of DCs after 24-h treatment with test biomaterials), DCs were CD1c+, CD11c+, CD123+, MMR+, CD14+, and CD64-. Furthermore, CD3+ and CD4+ T lymphocytes and CD19+ and CD24+ B lymphocytes were present in both cultures at all timepoints, although to different extents. Immature DCs (approximately 15 microm), were rounded but presented extensive dendritic processes upon maturation with lipopolysaccharide. Alternatively, adherent macrophages (approximately 15-20 microm) displayed internalized lipids and exhibited few membrane processes. The characterization and comparison of existing techniques to establish reliable, reproducible primary cultures of DCs or macrophages provides an important basis for examining and interpreting complex macrophage/DC-lymphocyte-orchestrated host responses in future studies with equivalent cell populations on test biomaterials.

PEG-PLA block copolymer as potential drug carrier: preparation and characterization

Diblock and multiblock copolymers composed of a poly(D,L-lactide) (PLA) or poly(trimethylene carbonate) (PTMC) core with a hydrophilic chain of poly(ethylene glycol) (PEG) were prepared. These copolymers, in which the core is connected to PEG through a polyfunctional molecule such as citric, mucic, or tartaric acid, may be used to form nanoparticles for drug delivery applications. Branched copolymers were prepared by direct amidation between the polyfunctional acid and methoxy PEGamine, followed by ring-opening polymerization of lactide or trimethyl carbonate to form the PLA and PTMC block copolymers. In addition, a complex multiblock copolymer of biotin-PEG-poly[lactic-co-(glycolic acid)] (PLGA) for application in an avidin-biotin system was prepared for possible design of nanospheres with targeting properties. Studies of drug release from polymeric systems containing multiblock copolymers and studies of polymer degradation were also performed.