Macrophage engulfment of a cell or nanoparticle is regulated by unavoidable opsonization, a species-specific 'Marker of Self' CD47, and target physical properties

Manipulation of Macrophage Uptake by Controlling the Aspect Ratio of Graft Copolymer Micelles

Nanostructures of drug carriers play a crucial role in nanomedicine due to their ability to influence drug delivery. There is yet no clear consensus regarding the optimal size and shape (e.g., aspect ratio) of nanoparticles for minimizing macrophage uptake, given the difficulties in controlling the shape and size of nanoparticles while maintaining identical surface properties. Here, we employed graft copolymer self-assembly to prepare polymer micelles with aspect ratios ranging from 1.0 (spherical) to 10.8 (cylindrical) and closely matched interfacial properties. Notably, our findings emphasize that cylindrical micelles with an aspect ratio of 2.4 are the least susceptible to macrophage uptake compared with both their longer counterparts and spherical micelles. This reduced uptake of the short cylindrical micelles results in a 3.3-fold increase in blood circulation time compared with their spherical counterparts. Controlling the aspect ratio of nanoparticles is crucial for improving drug delivery efficacy through better nanoparticle design.

Design of nanoparticle-based systems for the systemic delivery of chemotherapeutics: Alternative potential routes via sublingual and buccal administration for systemic drug delivery

Conventional therapeutic approaches for cancer generally involve chemo- and radiation therapies that often exhibit low efficacy and induce toxic side effects. Recent years have seen significant advancements in the use of protein biologics as a promising alternative treatment option. Nanotechnology-based systems have shown great potential in providing more specific and targeted cancer treatments, thus improving upon many of the limitations associated with current treatments. The unique properties of biomaterial carriers at the nanoscale have been proven to enhance both the performance of the incorporated therapeutic agent and tumor targeting; however, many of these systems are delivered intravenously, which can cause hazardous side effects. Buccal and sublingual delivery systems offer an alternative route for more efficient delivery of nanotechnologies and drug absorption into systemic circulation. This review concentrates on emerging buccal and sublingual nanoparticle delivery systems for chemo- and protein therapeutics, their development, efficacy, and potential areas of improvement in the field. Several factors contribute to the development of effective buccal or sublingual nanoparticle delivery systems, including targeting efficiency of the nanoparticulate carriers, drug release, and carrier biocompatibility. Furthermore, the potential utilization of buccal and sublingual multilayer films combined with nanoparticle chemotherapeutic systems is outlined as a future avenue for in vitro and in vivo research.

A Biomimetic Nanoparticle Exerting Protection against Acute Liver Failure by Suppressing CYP2E1 Activity and Scavenging Excessive ROS

Acute liver failure (ALF) is a severe liver disease caused by many reasons. One of them is the overdosed acetaminophen (APAP), which is metabolized into N-acetyl-p-benzoquinone imine (NAPQI), an excessive toxic metabolite, by CYP2E1, resulting in excessive reactive oxygen species (ROS), exhausted glutathione (GSH), and thereafter hepatocyte necrosis. N-acetylcysteine is the Food and Drug Administration-approved drug for detoxification of APAP, but it has limited clinical application due to the short therapeutic time window and concentration-related adverse effects. In this study, a carrier-free and bilirubin dotted nanoparticle (B/BG@N) is developed, which is formed using bilirubin and 18β-Glycyrrhetinic acid, and bovine serum albumin (BSA) is then adsorbed to mimic the in vivo behavior of the conjugated bilirubin for hitchhiking. The results demonstrate that B/BG@N can effectively reduce the production of NAPQI as well as exhibit antioxidant effects against intracellular oxidative stress via regulating the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 signal axis and reducing the production of inflammatory factors. In vivo study shows that B/BG@N can effectively improve the clinical symptom of the mice model. This study suggests that B/BG@N own increases circulation half-life, improves accumulation in the liver, and dual detoxification, providing a promising strategy for clinical ALF treatment.

The Role of Integrins for Mediating Nanodrugs to Improve Performance in Tumor Diagnosis and Treatment

Integrins are heterodimeric transmembrane proteins that mediate adhesive connections between cells and their surroundings, including surrounding cells and the extracellular matrix (ECM). They modulate tissue mechanics and regulate intracellular signaling, including cell generation, survival, proliferation, and differentiation, and the up-regulation of integrins in tumor cells has been confirmed to be associated with tumor development, invasion, angiogenesis, metastasis, and therapeutic resistance. Thus, integrins are expected to be an effective target to improve the efficacy of tumor therapy. A variety of integrin-targeting nanodrugs have been developed to improve the distribution and penetration of drugs in tumors, thereby, improving the efficiency of clinical tumor diagnosis and treatment. Herein, we focus on these innovative drug delivery systems and reveal the improved efficacy of integrin-targeting methods in tumor therapy, hoping to provide prospective guidance for the diagnosis and treatment of integrin-targeting tumors.

Protein corona: Friend or foe? Co-opting serum proteins for nanoparticle delivery

For systemically delivered nanoparticles to reach target tissues, they must first circulate long enough to reach the target and extravasate there. A challenge is that the particles end up engaging with serum proteins and undergo immune cell recognition and premature clearance. The serum protein binding, also known as protein corona formation, is difficult to prevent, even with artificial protection via "stealth" coating. Protein corona may be problematic as it can interfere with the interaction of targeting ligands with tissue-specific receptors and abrogate the so-called active targeting process, hence, the efficiency of drug delivery. However, recent studies show that serum protein binding to circulating nanoparticles may be actively exploited to enhance their downstream delivery. This review summarizes known issues of protein corona and traditional strategies to control the corona, such as avoiding or overriding its formation, as well as emerging efforts to enhance drug delivery to target organs via nanoparticles. It concludes with a discussion of prevailing challenges in exploiting protein corona for nanoparticle development.

Suppressing or Enhancing Macrophage Engulfment through the Use of CD47 and Related Peptides

Foreign particles and microbes are rapidly cleared by macrophages in vivo, although many key aspects of uptake mechanisms remain unclear. "Self" cells express CD47 which functions as an anti-phagocytic ligand for SIRPα on macrophages, particularly when pro-phagocytic ligands such as antibodies are displayed in parallel. Here, we review CD47 and related "Self" peptides as modulators of macrophage uptake. Nanoparticles conjugated with either CD47 or peptides derived from its SIRPα binding site can suppress phagocytic uptake by macrophages in vitro and in vivo, with similar findings for CD47-displaying viruses. Drugs, dyes, and genes as payloads thus show increased delivery to targeted cells. On the other hand, CD47 expression by cancer cells enables such cells to evade macrophages and immune surveillance. This has motivated development of soluble antagonists to CD47-SIRPα, ranging from blocking antibodies in the clinic to synthetic peptides in preclinical models. CD47 and peptides are thus emerging as dual-use phagocytosis modulators against diseases.

Nanoarchitectonics for Photo-Controlled Intracellular Drug Release in Immune Modulation

Local stimuli differentiate monocytes into M2-like macrophages that mechanistically drive the pathologies in cancer and age-related macular degeneration (AMD). A photo-controlled nanodrug that halts macrophage polarization through Rho-associated kinase (ROCK) inhibition was developed. A small-molecule ROCK inhibitor, fasudil, was conjugated to a photo-responsive group and a short poly(ethylene glycol) (PEG) chain. This resulted in the novel amphiphilic prodrug, PEG-2-(4'-(di(prop-2-yn-1-yl)amino)-4-nitro-[1,1'-biphenyl]-yl)propan-1-ol (PANBP)-Fasudil, that spontaneously formed micelles. Ultraviolet (UV) irradiation of PEG-PANBP-Fasudil nanoparticles rapidly released fasudil. For visualization of linker degradation, a reporter nanoprobe was synthesized, in which 2-Me-4-OMe TokyoGreen (TG), a fluorophore that does not fluoresce in conjugation, was incorporated. Irradiation of nanoprobe-laden monocytes activated the reporter fluorophore. Cytokine stimulation differentiated monocytes into macrophages, while UV irradiation prevented polarization of PEG-PANBP-Fasudil nanoparticle-laden monocytes. Nanoarchitectonics-based design opens new possibilities for intracellular drug delivery and precise spatiotemporal immune cell modulation toward the development of new therapies.

Pulmonary drug delivery applications of natural polysaccharide polymer derived nano/micro-carrier systems: A review

Respiratory distress syndrome and pneumothorax are the foremost causes of death as a result of the changing lifestyle and increasing air pollution. Numerous approaches have been studied for the pulmonary delivery of drugs, proteins as well as peptides using meso/nanoparticles, nanocrystals, and liposomes. These nano/microcarrier systems (NMCs) loaded with drug provide better systemic as well as local action. Furthermore, natural polysaccharide-based polymers such as chitosan (CS), alginate (AG), hyaluronic acid, dextran, and cellulose are highly used for the preparation of nanoparticles and delivery of the drug into the pulmonary tract due to their advantageous properties such as low toxicity, high hydrophobicity, supplementary mucociliary clearance, mucoadhesivity, and biological efficacy. These properties ease the delivery of drugs onto the targeted site. Herein, recent advances in the natural polymer-derived NMCs have been reviewed for their transport and mechanism of action into the bronchiolar region as well as the respiratory region. Various physicochemical properties such as surface charge, size of nanocarrier system, surface modifications, and toxicological effects of these nanocarriers in vitro and in vivo are elucidated as well. Furthermore, challenges faced for the preparation of a model NMCs for pulmonary drug delivery are also discoursed.

pH-responsive glycodendrimer as a new active targeting agent for doxorubicin delivery

The present study synthesized a new kind of pH-responsive active targeting glycodendrimer (ATGD) for doxorubicin delivery to cancerous cells. First, the glycodendrimer was synthesized based on the cultivation of chitosan dendrons on amine-functionalized, silica-grafted cellulose nanocrystals. Afterward, glycodendrimer was conjugated with folic acid to provide a folate receptor-targeting agent. The response surface method was employed to obtain the optimum conditions for the preparation of doxorubicin-loaded ATGD. The effect of doxorubicin/ATGD ratio, temperature, and pH on doxorubicin loading capacity was evaluated, and high loading capacity was achieved under optimized conditions. After determining doxorubicin release pattern at acidic and physiological pH, ATGD cytotoxicity was surveyed by MTT assay. Based on the results, the loading behavior of doxorubicin onto ATGD was in good agreement with monolayer-physisorption, and drug release was Fickian diffusion-controlled. ATGD could release the doxorubicin much more at acidic pH than physiological pH, corresponding to pH-responsive release behavior. Results of MTT assay confirmed the cytotoxicity of doxorubicin-loaded ATGD in cancer cells, while ATGD (without drug) was biocompatible with no tangible toxicity. These results suggested that ATGD has the potential for the treatment of cancer.

LC3-Associated Phagocytosis in Bacterial Infection

LC3-associated phagocytosis (LAP) is a noncanonical autophagy process reported in recent years and is one of the effective mechanisms of host defense against bacterial infection. During LAP, bacteria are recognized by pattern recognition receptors (PRRs), enter the body, and then recruit LC3 onto a single-membrane phagosome to form a LAPosome. LC3 conjugation can promote the fusion of the LAPosomes with lysosomes, resulting in their maturation into phagolysosomes, which can effectively kill the identified pathogens. However, to survive in host cells, bacteria have also evolved strategies to evade killing by LAP. In this review, we summarized the mechanism of LAP in resistance to bacterial infection and the ways in which bacteria escape LAP. We aim to provide new clues for developing novel therapeutic strategies for bacterial infectious diseases.

Macromolecular conjugated cyanine fluorophore nanoparticles for tumor-responsive photo nanotheranostics

For photothermal therapy (PTT), the improved targeting can decrease the dosage and promote the therapeutic function of photothermal agents, which would effectively improve the antitumor effect. The tumor microenvironment (TME) and cells are targets in designing intelligent and responsive theranostics. However, most of these schemes have been limited to the traditional visible and first near-infrared (NIR-I) regions, eager to expand to the second near-infrared (NIR-II) window. We designed and synthesized a polyethylene glycol conjugated and disulfide-modified macromolecule fluorophore (MPSS). MPSS could self-assemble into core-shell micelles in an aqueous solution (MPSS-NPS), while the small molecule probes were in a high aggregation arrangement inside the nanoparticle. The pronounced aggregation quenching (ACQ) effect caused them to the "sleeping" state. After entering the tumor cells, the disulfide bonds in MPSS-NPS broke in response to a high concentration of glutathione (GSH) in TME, and the molecule probes were released. The highly aggregated state was effectively alleviated, resulting in distinct absorption enhancement in the near-infrared region. Therefore, the fluorescence signal was recovered, and the photothermal performance was triggered. In vitro and in vivo studies reveal that the Nano-system is efficient for the smart NIR-II fluorescence imaging-guided PTT, even at a low dosage and density of irradiation.

Protein corona-coated immunomagnetic nanoparticles with enhanced isolation of circulating tumor cells

Immunomagnetic nanoparticles (IMNs) have been widely developed as a detection tool to isolate rare circulating tumor cells (CTCs) from whole blood as a potential method for early cancer diagnosis, metastasis examination, and treatment guidance. However, a spontaneous interaction between nanoparticles and proteins results in the formation of a protein corona that reduces the performance of IMNs when they enter body fluids. To address this issue, the protein corona was precoated onto magnetic nanoparticles (C-MNs), and then their surfaces were conjugated with an immuno-antibody. The adsorption of proteins on C-MNs was decreased 6-fold and non-specific cell binding was reduced 5-fold, compared with magnetic nanoparticles (MNs). Furthermore, the immuno-antibody functionalized C-MNs (IC-MNs) maintained highly specific CTC capture performance when exposed to blood plasma. By using artificial spiked blood samples, IC-MNs exhibited 90.2% CTC isolation efficiency, compared with 60.3% by using IMNs. IC-MNs also successfully captured CTCs with high purity in 24 out of 26 female breast cancer patient blood samples. This work demonstrated that a novel preformed protein corona strategy can provide a useful clinically applicable diagnostic tool.

Artificial engineering of the protein corona at bio-nano interfaces for improved cancer-targeted nanotherapy

Nanoparticles (NPs) have been demonstrated in numerous applications as anticancer, antibacterial and antioxidant agents. Artificial engineering of protein interactions with NPs in biological systems is crucial to develop potential NPs for drug delivery and cancer nanotherapy. The protein corona (PC) on the NP surface, displays an interface between biomacromolecules and NPs, governing their pharmacokinetics and pharmacodynamics. Upon interaction of proteins with the NP surface, their surface features are modified and they can easily be removed from the circulation by the mononuclear phagocytic system (MPS). PC properties heavily depend on the biological microenvironment and NP surface physicochemical parameters. Based on this context, we have surveyed different approaches that have been used for artificial engineering of the PC composition on NP surfaces. We discuss the effects of NP size, shape, surface modifications (PEGylation, self-peptide, other polymers), and protein pre-coating on the PC properties. Additionally, other factors including protein source and structure, intravenous injection and the subsequent shear flow, plasma protein gradients, temperature and local heat transfer, and washing media are considered in the context of their effects on the PC properties and overall target cellular effects. Moreover, the effects of NP-PC complexes on cancer cells based on cellular interactions, organization of intracellular PC (IPC), targeted drug delivery (TDD) and regulation of burst drug release profile of nanoplatforms, enhanced biocompatibility, and clinical applications were discussed followed by challenges and future perspective of the field. In conclusion, this paper can provide useful information to manipulate PC properties on the NP surface, thus trying to provide a literature survey to shorten their shipping from preclinical to clinical trials and to lay the basis for a personalized PC.

Opsonized nanoparticles target and regulate macrophage polarization for osteoarthritis therapy: A trapping strategy

Osteoarthritis (OA) is a chronic disease caused by joint inflammation. Its occurrence and development depend on a continuous inflammation environment. The activated M1 macrophages play a critical role in the inflammatory response of OA. Regulating the pro-inflammatory M1 to anti-inflammatory M2 macrophages in the OA articular cavity could be a rational strategy for OA treatment. It has been acknowledged that activated macrophages could proactively capture opsonized nanoparticles in the bloodstream and then accumulate into the reticuloendothelial system (RES) organs. Based on this fact, a trapping strategy is proposed, which transforms a normal nanoparticle into an opsonized attractant to target and regulate macrophage polarization. In this study, the opsonized nanoparticle (IgG/Bb@BRPL) had several key features, including an immunoglobulin IgG (the opsonized layer), an anti-inflammatory agent berberine (Bb), and an oxidative stress-responsive bilirubin grafted polylysine biomaterial (BR-PLL) for drug loading (the inner nanocore). In vitro studies confirmed that IgG/Bb@BRPL prefer to be phagocytosed by M1 macrophage, not M0. And the internalized IgG/Bb@BRPL effectively promoted macrophage polarization toward the M2 phenotype and protected nearby chondrocytes. In vivo studies suggested that IgG/Bb@BRPL significantly enhanced therapeutic outcomes by suppressing inflammation and promoting cartilage repair while not prolonging the retention period compared to non-opsonized counterparts. This proof-of-concept study provided a novel opsonization trapping strategy for OA drug delivery and treatment.

Strong π-π Stacking Stabilized Nanophotosensitizers: Improving Tumor Retention for Enhanced Therapy for Large Tumors in Mice

Conventional photosensitizers (PSs) often show poor tumor retention and are rapidly cleared from the bloodstream, which is one of the key hindrances to guarantee precise and efficient photodynamic therapy (PDT) in vivo. In this work, a photosensitizer assembly nanosystem that sharply enhances tumor retention up to ≈10 days is present. The PSs are synthesized by meso-substituting anthracene onto a BODIPY scaffold (AN-BDP), which then self-assembles into stable nanoparticles (AN-BDP NPs) with amphiphilic block copolymers due to the strong intermolecular π-π interaction of the anthracene. Additionally, the incorporated anthracene excites the PSs, producing singlet oxygen under red-light irradiation. Although AN-BDP NPs can completely suppress regular test size tumors (≈100 mm³ ) by one-time radiation, only 12% tumor growth inhibition rate is observed in the case of large-size tumors (≈350 mm³ ) under the same conditions. Due to the long-time tumor retention, AN-BDP NPs allow single-dose injection and three-time light treatments, resulting in an inhibition rate over 90%, much more efficient than single-time radiation of conventional clinically used PSs including chlorin-e6 (Ce6) and porphyrin with poor tumor retention. The results reveal the importance of long tumor retention time of PSs for efficient PDT, which can accelerate the clinical development of nanophotosensitizers.

Endothelial cell membrane-based biosurface for targeted delivery to acute injury: analysis of leukocyte-mediated nanoparticle transportation

Mimicking and leveraging biological structures and materials provide important approaches to develop functional vehicles for drug delivery. Taking advantage of the affinity and adhesion between the activated endothelial cells and innate immune cells during inflammatory responses, hybrid polyester nanoparticles coated with endothelial cell membranes (EM-P) containing adhesion molecules were fabricated and their capability as vehicles to travel to the acute injury sites through leukocyte-mediated processes was investigated. The in vivo studies and quantitative analyses performed through the lung-inflammation mouse models demonstrated that the EM-Ps preferentially interacted with the neutrophils and monocytes in the circulation and the cellular membrane-based biosurface improved the nanoparticle transportation to the inflamed lung possibly via the motility of neutrophils. Utilizing the transgenic zebrafish model, the leukocyte-mediated transportation and biodistribution of EM-Ps were further visualized in real time at the whole-organism level. Endothelial membranes provided a new biosurface for developing biomimetic vehicles to allow the immune cell-mediated transportation and may enable advanced systems for active and highly efficient drug delivery.

In Situ Membrane Biotinylation Enables the Direct Labeling and Accurate Kinetic Analysis of Small Extracellular Vesicles in Circulation

Circulating small extracellular vesicles (sEVs) are naturally occurring nanosized membrane vesicles that convey bioactive molecules between cells. Conventionally, to evaluate their behaviors in vivo, circulating sEVs have to be isolated from the bloodstream, then labeled with imaging materials in vitro, and finally injected back into the circulation of animals for subsequent detection. The tedious isolation-labeling-reinfusion procedures might have an undesirable influence on the natural properties of circulating sEVs, thereby changing their behaviors and the detected kinetics in vivo. Herein, we proposed an in situ biotinylation strategy to directly label circulating sEVs with intravenously injected DSPE-PEG-Biotin, aiming to evaluate the in vivo kinetics of circulating sEVs more biofriendly and accurately. Such an analysis strategy is free of isolation-labeling-reinfusion procedures and has no unfavorable influence on the natural behaviors of sEVs. The results showed that the lifetime of generic circulating sEVs in mice was around 3 days. Furthermore, we, for the first time, revealed the distinct in vivo kinetics of circulating sEV subpopulations with different cell sources, among which erythrocyte-derived sEVs showed the longest lifespan. Moreover, compared with circulating sEVs in situ or used as autograft, circulating sEVs used as allograft had the shortest lifetime. In addition, the in situ biotinylation strategy also provides a way for the enrichment of biotinylated circulating sEVs. In summary, this study provides a novel strategy for in situ labeling of circulating sEVs, which would facilitate the accurate characterization of their kinetics in vivo, thereby accelerating their future application as biomarkers and theranositic vectors.

Biomimetic recombinant of red blood cell membranes for improved photothermal therapy

Background

RBC membrane derived nanoparticles (NPs) represent an emerging platform with prolonged circulation capacity for the delivery of active substances. For functionalize derived RBCs NPs, various strategies, such as biomimetic rebuilding of RBCs, chemical modification or inserting ligands, have been carried out to improve their performance. However, one potential adverse effect for these methods is the structural failure of membrane proteins, consequently affecting its original immune escape function.

Results

In this study, we reported a green technology of “disassembly-reassembly” to prepare biomimetic reconstituted RBCs membrane (rRBCs) by separating the endogenous proteins and lipids from nature RBC membrane. IR780 iodide was used as a pattern drug to verify the property and feasibility of rRBCs by constructing IR780@rRBC NPs with IR780@RBC NPs and free IR780 as controls. The results demonstrated the superiority of IR780@rRBC NPs in toxicity, stability, pharmacokinetics and pharmacodynamics compared with IR780@rRBC and free IR780.

Conclusions

The reported “disassembly-reassembly” strategy shows great potential to produce controllable and versatile rRBC membrane-inspired delivery platform, which may be used to overcome the deficiency of functionalization in cell membrane coated nanoparticles .

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00949-7.

Enhancing subcutaneous injection and target tissue accumulation of nanoparticles via co-administration with macropinocytosis inhibitory nanoparticles (MiNP)

A significant barrier to the application of nanoparticles for precision medicine is the mononuclear phagocyte system (MPS), a diverse population of phagocytic cells primarily located within the liver, spleen and lymph nodes. The majority of nanoparticles are indiscriminately cleared by the MPS via macropinocytosis before reaching their intended targets, resulting in side effects and decreased efficacy. Here, we demonstrate that the biodistribution and desired tissue accumulation of targeted nanoparticles can be significantly enhanced by co-injection with polymeric micelles containing the actin depolymerizing agent latrunculin A. These macropinocytosis inhibitory nanoparticles (MiNP) were found to selectively inhibit non-specific uptake of a second "effector" nanoparticle in vitro without impeding receptor-mediated endocytosis. In tumor bearing mice, co-injection with MiNP in a single multi-nanoparticle formulation significantly increased the accumulation of folate-receptor targeted nanoparticles within tumors. Furthermore, subcutaneous co-administration with MiNP allowed effector nanoparticles to achieve serum levels that rivaled a standard intravenous injection. This effect was only observed if the effector nanoparticles were injected within 24 h following MiNP administration, indicating a temporary avoidance of MPS cells. Co-injection with MiNP therefore allows reversible evasion of the MPS for targeted nanoparticles and presents a previously unexplored method of modulating and improving nanoparticle biodistribution following subcutaneous administration.

Targeting CD47 Inhibits Tumor Development and Increases Phagocytosis in Oral Squamous Cell Carcinoma

BACKGROUND

Our previous work demonstrated upregulated CD47 in Oral Squamous Cell Carcinoma (OSCC).

OBJECTIVE

In the present study, we aimed to investigate the effects of CD47 on tumor cell development and phagocytosis in OSCC and elucidate the underlying mechanisms.

METHODS

The proliferation, apoptosis, migration, and invasion of oral cancer cells were analyzed after knocking down the expression of CD47. The effects of CD47 on tumor development were also evaluated using a murine model of OSCC. The involvement of CD47 in the phagocytosis of oral cancer cells was identified.

RESULTS

Cell proliferation was suppressed by knocking down the expression of CD47 in human OSCC cell line Cal-27 cells but there was no change in the apoptosis rate. Moreover, impaired expression of CD47 inhibited the migration and invasion of Cal-27 cells. Furthermore, we found that nude mice injected with CD47 knockeddown Cal-27 cells displayed decreased tumor volumes at week 9 compared to xenograft transplantations of blank Cal-27 cells. In addition, in vitro phagocytosis of Cal-27 cells by macrophages was significantly enhanced after the knockdown of CD47, which positively correlated with compromised STAT3/JAK2 signaling.

CONCLUSION

In summary, the knockdown of CD47 downregulated the development of OSCC and increased the phagocytosis of Cal-27 cells, indicating that CD47 might be a promising therapeutic target.

Reversing cold tumors to hot: An immunoadjuvant-functionalized metal-organic framework for multimodal imaging-guided synergistic photo-immunotherapy

Immunotherapy assays using immunoadjuvants and tumor antigens could greatly increase the survival rates of patients with malignant tumors. As effective carriers, metal-organic frameworks (MOFs) have been widely utilized in cancer therapy due to their remarkable histocompatibility and low toxicity. Herein, we constructed a multimodal imaging-guided synergistic cancer photoimmunotherapy by employing a specific MOF (MIL101-NH₂) as the core carrier; the MOF was dual-dressed with photoacoustic and fluorescent signal donors (indocyanine green, ICG) and immune adjuvants (cytosine-phosphate-guanine sequence, CpG) and named ICG-CpG@MOF. This nanocarrier could passively target the tumor site through the EPR effect and achieve multimodal imaging (fluorescence, photoacoustic, photothermal and magnetic resonance imaging) of the tumor. Synergistic cancer photoimmunotherapy was achieved via simultaneous photodynamic and photothermal methods with 808 nm laser irradiation. ICG-CpG@MOF achieved the GSH-controlled release of immunoadjuvant into the tumor microenvironment. Furthermore, the released tumor-associated antigen along with CpG could induce the transformation of tumor cells from cold to hot by activating the immune system, which significantly enhanced tumor cytotoxicity and achieved high cure rates with minimal side-effects. This strategy utilizing multimodal imaging and synergistic cancer photoimmunotherapy provides a promising approach for the diagnosis and treatment of cancer.

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Tumor microenvironment and light dual-response nanoplatform realize multi-modal imaging-guided cancer photo-immunotherapy.

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When light triggers photothermal therapy, the immune system is activated to play a long-acting anti-tumor effect.

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Nanoscale MOF could accumulate at the tumor site via the EPR effect and tumor-enhanced micropinocytosis.

Mechanobiology of Macrophages: How Physical Factors Coregulate Macrophage Plasticity and Phagocytosis

In addition to their early-recognized functions in host defense and the clearance of apoptotic cell debris, macrophages play vital roles in tissue development, homeostasis, and repair. If misregulated, they steer the progression of many inflammatory diseases. Much progress has been made in understanding the mechanisms underlying macrophage signaling, transcriptomics, and proteomics, under physiological and pathological conditions. Yet, the detailed mechanisms that tune circulating monocytes/macrophages and tissue-resident macrophage polarization, differentiation, specification, and their functional plasticity remain elusive. We review how physical factors affect macrophage phenotype and function, including how they hunt for particles and pathogens, as well as the implications for phagocytosis, autophagy, and polarization from proinflammatory to prohealing phenotype. We further discuss how this knowledge can be harnessed in regenerative medicine and for the design of new drugs and immune-modulatory drug delivery systems, biomaterials, and tissue scaffolds.

Switch of macrophage fusion competency by 3D matrices

Foreign body reaction reflects the integration between biomaterials and host cells. At the implantation microenvironment, macrophages usually fuse into multinuclear cells, also known as foreign body giant cells, to respond to the biomaterial implants. To understand the biomaterial-induced macrophage fusion, we examined whether biomaterial alone can initiate and control the fusion rate without exogenous cytokines and chemicals. We introduced a collagen-based 3D matrix to embed Raw264.7 cell line and primary rat bone marrow-derived macrophages. We found the biomaterial-stimuli interacted regional macrophages and altered the overall fusogenic protein expressions to regulate the macrophage fusion rate. The fusion rate could be altered by modulating the cell-matrix and cell-cell adhesions. The fused macrophage morphologies, the nuclei number in the fused macrophage, and the fusion rates were matrix dependent. The phenomena were also observed in the in vivo models. These results suggest that the biomaterial-derived stimuli exert similar functions as cytokines to alter the competency of macrophage fusion as well as their drug sensitivity in the biomaterial implanted tissue environment. Furthermore, this in vitro 3D-matrix model has the potential to serve as a toolbox to predict the host tissue response on implanted biomaterials.

Cell Membrane-Based Biomimetic Nanoparticles and the Immune System: Immunomodulatory Interactions to Therapeutic Applications

Nanoparticle-based drug delivery systems have been synthesized from a wide array of materials. The therapeutic success of these platforms hinges upon their ability to favorably interact with the biological environment (both systemically and locally) and recognize the diseased target tissue. The immune system, composed of a highly coordinated organization of cells trained to recognize foreign bodies, represents a key mediator of these interactions. Although components of this system may act as a barrier to nanoparticle (NP) delivery, the immune system can also be exploited to target and trigger signaling cues that facilitate the therapeutic response stemming from systemic administration of NPs. The nano-bio interface represents the key facilitator of this communication exchange, where the surface properties of NPs govern their in vivo fate. Cell membrane-based biomimetic nanoparticles have emerged as one approach to achieve targeted drug delivery by actively engaging and communicating with the biological milieu. In this review, we will highlight the relationship between these biomimetic nanoparticles and the immune system, emphasizing the role of tuning the nano-bio interface in the immunomodulation of diseases. We will also discuss the therapeutic applications of this approach with biomimetic nanoparticles, focusing on specific diseases ranging from cancer to infectious diseases. Lastly, we will provide a critical evaluation on the current state of this field of cell membrane-based biomimetic nanoparticles and its future directions in immune-based therapy.

Friend or Foe? Recent Strategies to Target Myeloid Cells in Cancer

The tumor microenvironment (TME) is a complex network of epithelial and stromal cells, wherein stromal components provide support to tumor cells during all stages of tumorigenesis. Among these stromal cell populations are myeloid cells, which are comprised mainly of tumor-associated macrophages (TAM), dendritic cells (DC), myeloid-derived suppressor cells (MDSC), and tumor-associated neutrophils (TAN). Myeloid cells play a major role in tumor growth through nurturing cancer stem cells by providing growth factors and metabolites, increasing angiogenesis, as well as promoting immune evasion through the creation of an immune-suppressive microenvironment. Immunosuppression in the TME is achieved by preventing critical anti-tumor immune responses by natural killer and T cells within the primary tumor and in metastatic niches. Therapeutic success in targeting myeloid cells in malignancies may prove to be an effective strategy to overcome chemotherapy and immunotherapy limitations. Current therapeutic approaches to target myeloid cells in various cancers include inhibition of their recruitment, alteration of function, or functional re-education to an antitumor phenotype to overcome immunosuppression. In this review, we describe strategies to target TAMs and MDSCs, consisting of single agent therapies, nanoparticle-targeted approaches and combination therapies including chemotherapy and immunotherapy. We also summarize recent molecular targets that are specific to myeloid cell populations in the TME, while providing a critical review of the limitations of current strategies aimed at targeting a single subtype of the myeloid cell compartment. The goal of this review is to provide the reader with an understanding of the critical role of myeloid cells in the TME and current therapeutic approaches including ongoing or recently completed clinical trials.

TSP1-CD47-SIRPα signaling facilitates the development of endometriosis by mediating the survival of ectopic endometrium

PROBLEM

To explore whether the thrombospondin-1(TSP1)-CD47-signal regulatory protein alpha (SIRPα) signaling pathway has impacts on the development of endometriosis.

METHOD OF STUDY

Endometrial stromal cells (ESCs) originated from ectopic and eutopic endometrial tissues with or without endometriosis. Monocytes (Macrophages) were isolated from peripheral blood and peritoneal fluids with or without endometriosis. The expression levels of molecules were investigated by flow cytometry (FCM), immunohistochemistry (IHC), and RT-qPCR. The concentration of TSP1 was assessed via ELISA. The capacities of angiogenesis and phagocytosis were measured via tube formation assay and phagocytic assay, respectively.

RESULTS

We confirmed the up-regulation of critical molecules within the pathway in endometriosis patients. TSP1 can encourage normal ESCs (NESCs) growth and fibrosis. It simultaneously promotes the secretion of inflammatory factors and inhibits the phagocytic abilities of macrophages. Moreover, the proliferation of vascular endothelial cells (VECs) may be improved by TSP1. These effects may be offset by CD47 blocking antibodies. In addition, ectopic ESCs (EESCs) directly improve SIRPα expression on macrophages, which may further exhaust their phagocytic ability. Phagocytosis efficiency of macrophages on EESCs significantly improves by blocking CD47-SIRPα pathway.

CONCLUSION

TSP1-CD47-SIRPα signaling pathway not only improves the viability of NESCs per se but also promotes their survival circumstances by affecting the function of macrophages and VECs, which are mutually reinforcing and jointly promote the development of endometriosis.

Reimaging biological barriers affecting distribution and extravasation of PEG/peptide- modified liposomes in xenograft SMMC7721 tumor

Liposomes, as one of the most successful nanotherapeutics, have a major impact on many biomedical areas. In this study, we performed laser scanning confocal microscope (LSCM) and immunohistochemistry (IHC) assays to investigate the intra-tumor transport and antitumor mechanism of GE11 peptide-conjugated active targeting liposomes (GE11-TLs) in SMMC7721 xenograft model. According to classification of individual cell types in high resolution images, biodistribution of macrophages, tumor cells, cells with high epidermal growth factor receptor (EGFR) expression and interstitial matrix in tumor microenvironment, in addition, their impacts on intra-tumor penetration of GE11-TLs were estimated. Type I collagen fibers and macrophage flooded in the whole SMMC7721 tumor xenografts. Tumor angiogenesis was of great heterogeneity from the periphery to the center region. However, the receptor-binding site barriers were supposed to be the leading cause of poor penetration of GE11-TLs. We anticipate these images can give a deep reconsideration for rational design of target nanoparticles for overcoming biological barriers to drug delivery.

A post-transcriptional program of chemoresistance by AU-rich elements and TTP in quiescent leukemic cells

BACKGROUND

Quiescence (G0) is a transient, cell cycle-arrested state. By entering G0, cancer cells survive unfavorable conditions such as chemotherapy and cause relapse. While G0 cells have been studied at the transcriptome level, how post-transcriptional regulation contributes to their chemoresistance remains unknown.

RESULTS

We induce chemoresistant and G0 leukemic cells by serum starvation or chemotherapy treatment. To study post-transcriptional regulation in G0 leukemic cells, we systematically analyzed their transcriptome, translatome, and proteome. We find that our resistant G0 cells recapitulate gene expression profiles of in vivo chemoresistant leukemic and G0 models. In G0 cells, canonical translation initiation is inhibited; yet we find that inflammatory genes are highly translated, indicating alternative post-transcriptional regulation. Importantly, AU-rich elements (AREs) are significantly enriched in the upregulated G0 translatome and transcriptome. Mechanistically, we find the stress-responsive p38 MAPK-MK2 signaling pathway stabilizes ARE mRNAs by phosphorylation and inactivation of mRNA decay factor, Tristetraprolin (TTP) in G0. This permits expression of ARE mRNAs that promote chemoresistance. Conversely, inhibition of TTP phosphorylation by p38 MAPK inhibitors and non-phosphorylatable TTP mutant decreases ARE-bearing TNFα and DUSP1 mRNAs and sensitizes leukemic cells to chemotherapy. Furthermore, co-inhibiting p38 MAPK and TNFα prior to or along with chemotherapy substantially reduces chemoresistance in primary leukemic cells ex vivo and in vivo.

CONCLUSIONS

These studies uncover post-transcriptional regulation underlying chemoresistance in leukemia. Our data reveal the p38 MAPK-MK2-TTP axis as a key regulator of expression of ARE-bearing mRNAs that promote chemoresistance. By disrupting this pathway, we develop an effective combination therapy against chemosurvival.

Fate of GdF3 nanoparticles-loaded PEGylated carbon capsules inside mice model: a step toward clinical application

The successful translation of nanostructure-based bioimaging and/or drug delivery system needs extensive in vitro and in vivo studies on biocompatibility, biodistribution, clearance, and toxicity for its diagnostic applications. Herein, we have investigated the in vitro cyto-hemocompatibility, in vivo biodistribution, clearance, and toxicity in mice after systemic administration of GdF₃ nanoparticles loaded PEGylated mesoporous carbon capsule (GdF₃-PMCC)-based theranostic system. In vitro cyto-hemocompatibility study showed a very good biocompatibility up to concentration of 500 µg/ml. Biodistribution studies carried out from 1 h to 8 days showed that GdF₃-PMCC was found in major organs, such as liver, kidney, spleen, and muscle till 4th day and it was negligible in any tissue after 8th day. The clearance study was carried out for a period of 8 days and it was observed that the urinary system is the main route of excretion of GdF₃-PMCC. The tissue toxicity study was done for 15 days and histopathological analysis indicated that the GdF₃-PMCC based theranostic system does not have any adverse effect in tissues. Thus, PMCCs are nontoxic and can be applied as theranostic agents in contrast to the other carbon-based systems (PEGylated carbon nanotubes and PEGylated graphene oxide) which showed significant toxicity.

Biointerface engineering nanoplatforms for cancer-targeted drug delivery

Over the past decade, nanoparticle-based therapeutic modalities have become promising strategies in cancer therapy. Selective delivery of anticancer drugs to the lesion sites is critical for elimination of the tumor and an improved prognosis. Innovative design and advanced biointerface engineering have promoted the development of various nanocarriers for optimized drug delivery. Keeping in mind the biological framework of the tumor microenvironment, biomembrane-camouflaged nanoplatforms have been a research focus, reflecting their superiority in cancer targeting. In this review, we summarize the development of various biomimetic cell membrane-camouflaged nanoplatforms for cancer-targeted drug delivery, which are classified according to the membranes from different cells. The challenges and opportunities of the advanced biointerface engineering drug delivery nanosystems in cancer therapy are discussed.

Biodegraded magnetosomes with reduced size and heating power maintain a persistent activity against intracranial U87-Luc mouse GBM tumors

BACKGROUND

An important but rarely addressed question in nano-therapy is to know whether bio-degraded nanoparticles with reduced sizes and weakened heating power are able to maintain sufficient anti-tumor activity to fully eradicate a tumor, hence preventing tumor re-growth. To answer it, we studied magnetosomes, which are nanoparticles synthesized by magnetotactic bacteria with sufficiently large sizes (~ 30 nm on average) to enable a follow-up of nanoparticle sizes/heating power variations under two different altering conditions that do not prevent anti-tumor activity, i.e. in vitro cellular internalization and in vivo intra-tumor stay for more than 30 days.

RESULTS

When magnetosomes are internalized in U87-Luc cells by being incubated with these cells during 24 h in vitro, the dominant magnetosome sizes within the magnetosome size distribution (DMS) and specific absorption rate (SAR) strongly decrease from DMS ~ 40 nm and SAR ~ 1234 W/gFe before internalization to DMS ~ 11 nm and SAR ~ 57 W/gFe after internalization, a behavior that does not prevent internalized magnetosomes to efficiently destroy U87-Luc cell, i.e. the percentage of U87-Luc living cells incubated with magnetosomes decreases by 25% between before and after alternating magnetic field (AMF) application. When 2 µl of a suspension containing 40 µg of magnetosomes are administered to intracranial U87-Luc tumors of 2 mm3 and exposed (or not) to 15 magnetic sessions (MS), each one consisting in 30 min application of an AMF of 27 mT and 198 kHz, DMS and SAR decrease between before and after the 15 MS from ~ 40 nm and ~ 4 W/gFe down to ~ 29 nm and ~ 0 W/gFe. Although the magnetosome heating power is weakened in vivo, i.e. no measurable tumor temperature increase is observed after the sixth MS, anti-tumor activity remains persistent up to the 15th MS, resulting in full tumor disappearance among 50% of treated mice.

CONCLUSION

Here, we report sustained magnetosome anti-tumor activity under conditions of significant magnetosome size reduction and complete loss of magnetosome heating power.

Albumin Nanovectors in Cancer Therapy and Imaging

Albumin nanovectors represent one of the most promising carriers recently generated because of the cost-effectiveness of their fabrication, biocompatibility, safety, and versatility in delivering hydrophilic and hydrophobic therapeutics and diagnostic agents. In this review, we describe and discuss the recent advances in how this technology has been harnessed for drug delivery in cancer, evaluating the commonly used synthesis protocols and considering the key factors that determine the biological transport and the effectiveness of such technology. With this in mind, we highlight how clinical and experimental albumin-based delivery nanoplatforms may be designed for tackling tumor progression or improving the currently established diagnostic procedures.

Particle toxicology and health - where are we?

Background

Particles and fibres affect human health as a function of their properties such as chemical composition, size and shape but also depending on complex interactions in an organism that occur at various levels between particle uptake and target organ responses.

While particulate pollution is one of the leading contributors to the global burden of disease, particles are also increasingly used for medical purposes. Over the past decades we have gained considerable experience in how particle properties and particle-bio interactions are linked to human health. This insight is useful for improved risk management in the case of unwanted health effects but also for developing novel medical therapies. The concepts that help us better understand particles’ and fibres’ risks include the fate of particles in the body; exposure, dosimetry and dose-metrics and the 5 Bs: bioavailability, biopersistence, bioprocessing, biomodification and bioclearance of (nano)particles. This includes the role of the biomolecule corona, immunity and systemic responses, non-specific effects in the lungs and other body parts, particle effects and the developing body, and the link from the natural environment to human health. The importance of these different concepts for the human health risk depends not only on the properties of the particles and fibres, but is also strongly influenced by production, use and disposal scenarios.

Conclusions

Lessons learned from the past can prove helpful for the future of the field, notably for understanding novel particles and fibres and for defining appropriate risk management and governance approaches.

PEGylated and CD47-conjugated nanoellipsoidal artificial antigen-presenting cells minimize phagocytosis and augment anti-tumor T-cell responses

Purpose

Antigen-presenting cells (APCs) are powerful tools to expand antigen-specific T cells ex vivo and in vivo for tumor immunotherapy, but suffer from time-consuming generation and biosafety concerns raised by live cells. Alternatively, the cell-free artificial antigen-presenting cells (aAPCs) have been rapidly developed. Nanoscale aAPCs are recently proposed owing to their superior biodistribution and reduced embolism than conventional cell-sized aAPCs, but pose the challenges: easier cellular uptake and smaller contact surface area with T cells than the cell-sized counterparts. This study aimed to fabricate a new “stealth” nano-aAPCs with microscale contact surface area to minimize cellular uptake and activate antigen-specific T cells by combination uses of ellipsoidal stretch, PEGylation, and self-marker CD47-Fc conjugation.

Methods

The spherical polylactic-co-glycolic acid nanoparticles were fabricated using a double-emulsion method, and then stretched twofold using film-stretching procedure followed by PEGylation and co-coupling with CD47-Fc, H-2K^b/TRP2_180-188-Ig dimers, and anti-CD28. The resulting PEGylated and CD47-conjugated nanoellipsoidal aAPCs (EaAPC^PEG/CD47) were co-cultured with macrophages or spleen lymphocytes and also infused into melanoma-bearing mice. The in vitro and in vivo effects were evaluated and compared with the nanospherical aAPCs (SaAPC), nanoellipsoidal aAPCs (EaAPC), or PEGylated nanoellipsoidal aAPC (EaAPC^PEG).

Results

EaAPC^PEG/CD47 markedly reduced cellular uptake in vitro and in vivo, as compared with EaAPC^PEG, EaAPC, SaAPC, and Blank-NPs and expanded naïve TRP2_180-188-specific CD8⁺ T cells in the co-cultures with spleen lymphocytes. After three infusions, the EaAPC^PEG/CD47 showed much stronger effects on facilitating TRP2_180-188-specific CD8⁺ T-cell proliferation, local infiltration, and tumor necrosis in the melanoma-bearing mice and on inhibiting tumor growth than the control aAPCs.

Conclusion

The superimposed or synergistic effects of ellipsoidal stretch, PEGylation, and CD47-Fc conjugation minimized cellular uptake of nano-aAPCs and enhanced their functionality to expand antigen-specific T cells and inhibit tumor growth, thus suggesting a more valuable strategy to design “stealth” nanoscale aAPCs suitable for tumor active immunotherapy.

Blood Circulation-Prolonging Peptides for Engineered Nanoparticles Identified via Phage Display

Sustaining blood retention for theranostic nanoparticles is a big challenge. Various approaches have been attempted and have demonstrated some success but limitations remain. We hypothesized that peptides capable of increasing blood residence time for M13 bacteriophage, a rod-shaped nanoparticle self-assembled from proteins and nucleic acids, should also prolong blood circulation for engineered nanoparticles. Here we demonstrate the feasibility of this approach by identifying a series of blood circulation-prolonging (BCP) peptides through in vivo screening of an M13 peptide phage display library. Intriguingly, the majority of the identified BCP peptides contained an arginine-glycine-aspartic acid (RGD) motif, which was necessary but insufficient for the circulation-prolonging activity. We further demonstrated that the RGD-mediated specific binding to platelets was primarily responsible for the enhanced blood retention of BCP1. The utility of the BCP1 peptide was demonstrated by fusion of the peptide to human heavy-chain ferritin (HFn), leading to significantly improved pharmacokinetic profile, enhanced tumor cell uptake and optimum anticancer efficacy for doxorubicin encapsulated in the HFn nanocage. Our results provided a proof-of-concept for an innovative yet simple strategy, which utilizes phage display to discover novel peptides with the capability of substantially prolonging blood circulation for engineered theranostic nanoparticles.

Safety Assessment of Graphene-Based Materials: Focus on Human Health and the Environment

Graphene and its derivatives are heralded as "miracle" materials with manifold applications in different sectors of society from electronics to energy storage to medicine. The increasing exploitation of graphene-based materials (GBMs) necessitates a comprehensive evaluation of the potential impact of these materials on human health and the environment. Here, we discuss synthesis and characterization of GBMs as well as human and environmental hazard assessment of GBMs using in vitro and in vivo model systems with the aim to understand the properties that underlie the biological effects of these materials; not all GBMs are alike, and it is essential that we disentangle the structure-activity relationships for this class of materials.

Alterations in Cellular Processes Involving Vesicular Trafficking and Implications in Drug Delivery

Endocytosis and vesicular trafficking are cellular processes that regulate numerous functions required to sustain life. From a translational perspective, they offer avenues to improve the access of therapeutic drugs across cellular barriers that separate body compartments and into diseased cells. However, the fact that many factors have the potential to alter these routes, impacting our ability to effectively exploit them, is often overlooked. Altered vesicular transport may arise from the molecular defects underlying the pathological syndrome which we aim to treat, the activity of the drugs being used, or side effects derived from the drug carriers employed. In addition, most cellular models currently available do not properly reflect key physiological parameters of the biological environment in the body, hindering translational progress. This article offers a critical overview of these topics, discussing current achievements, limitations and future perspectives on the use of vesicular transport for drug delivery applications.

Membrane fluctuations and acidosis regulate cooperative binding of 'marker of self' protein CD47 with the macrophage checkpoint receptor SIRPα

Cell-cell interactions that result from membrane proteins binding weakly in trans can cause accumulations in cis that suggest cooperativity and thereby an acute sensitivity to environmental factors. The ubiquitous 'marker of self' protein CD47 binds weakly to SIRPα on macrophages, which leads to accumulation of SIRPα (also known as SHPS-1, CD172A and SIRPA) at phagocytic synapses and ultimately to inhibition of engulfment of 'self' cells - including cancer cells. We reconstituted this macrophage checkpoint with GFP-tagged CD47 on giant vesicles generated from plasma membranes and then imaged vesicles adhering to SIRPα immobilized on a surface. CD47 diffusion is impeded near the surface, and the binding-unbinding events reveal cooperative interactions as a concentration-dependent two-dimensional affinity. Membrane fluctuations out-of-plane link cooperativity to membrane flexibility with suppressed fluctuations in the vicinity of bound complexes. Slight acidity (pH 6) stiffens membranes, diminishes cooperative interactions and also reduces 'self' signaling of cancer cells in phagocytosis. Sensitivity of cell-cell interactions to microenvironmental factors - such as the acidity of tumors and other diseased or inflamed sites - can thus arise from the collective cooperative properties of flexible membranes.This article has an associated First Person interview with the first author of the paper.

Reassessment of long circulation via monitoring of integral polymeric nanoparticles justifies a more accurate understanding

Monitoring of payloads results in a biased perception of long circulation of nanoparticles. Instead, herein, the long-circulation effect was re-confirmed by monitoring integral nanoparticles, but circulation was not found to be as long as generally perceived. In contrast, disparate pharmacokinetics were obtained by monitoring a model drug, paclitaxel, highlighting the bias of the conventional protocol.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

Tracking translocation of self-discriminating curcumin hybrid nanocrystals following intravenous delivery

Nanocrystals hold great potential as parenteral delivery carrier systems for poorly water-soluble drugs. Elucidation of the in vivo fate of parenteral nanocrystals is of pharmacological, toxicological and mechanistic significance. However, it is of tremendous difficulty to monitor real-time translocation of nanocrystals in vivo owing to progressive dissolution of nanocrystals and a lack of workable tools to probe nanocrystals. In this study, self-discriminating hybrid nanocrystals (SDHNs) of a model drug curcumin (CUR) were developed by embedding traces of environment-responsive fluorescent dyes into the crystalline lattices of CUR. The SDHNs glow, but the released dyes aggregate and quench spontaneously due to the aggregation-caused quenching (ACQ) effect. Following intravenous administration into rats, a large fraction of CUR nanocrystals are cleared from blood rapidly and accumulate mainly in liver and lung. A small fraction circulate in blood for at least 48 h. Long circulating might be attributable to the surface coating with poloxamer 188, a stabilizer used during preparation; nevertheless, the ultimate fate of nanocrystals ends in reticulo-endothelial organs and tissues. It is implied that parenteral delivery provide sustained release and prolonged pharmacological efficacy, but concomitantly raise concerns of local toxicity in vital organs and tissues, especially when the active ingredients are highly toxic.

Unintended effects of drug carriers: Big issues of small particles

Humoral and cellular host defense mechanisms including diverse phagocytes, leukocytes, and immune cells have evolved over millions of years to protect the body from microbes and other external and internal threats. These policing forces recognize engineered sub-micron drug delivery systems (DDS) as such a threat, and react accordingly. This leads to impediment of the therapeutic action, extensively studied and discussed in the literature. Here, we focus on side effects of DDS interactions with host defenses. We argue that for nanomedicine to reach its clinical potential, the field must redouble its efforts in understanding the interaction between drug delivery systems and the host defenses, so that we can engineer safer interventions with the greatest potential for clinical success.

CD63, MHC class 1, and CD47 identify subsets of extracellular vesicles containing distinct populations of noncoding RNAs

Extracellular vesicles (EVs) mediate the intercellular transfer of RNAs, which alter gene expression in target cells. EV heterogeneity has limited progress towards defining their physiological functions and utility as disease-specific biomarkers. CD63 and MHC1 are widely used as markers to purify EVs. CD47 is also present on EVs and alters their effects on target cells, suggesting that specific surface markers define functionally distinct EVs. This hypothesis was addressed by comparing Jurkat T cell EVs captured using CD47, CD63, and MHC1 antibodies. These EV subsets have similar sizes but divergent RNA contents. Apart from differences in numbers of nonannotated transcripts, CD63⁺, MHC1⁺, and CD47⁺ EVs have similar overall contents of most noncoding RNA classes, but the relative enrichment of specific RNAs differs. The enrichment of micro-RNAs is highly divergent, and some including miR320a are selectively concentrated in CD47⁺ EVs. Small nucleolar RNAs including SNORD116@ and SNHG10 are also selectively enriched in CD47⁺ EVs, whereas no small nuclear RNAs are enriched in CD47⁺ EVs. Conversely, MHC1⁺ EVs are selectively enriched in a subset of tRNAs including TRE-CTC and TRR-CCG. This heterogeneity in RNA composition suggests multiple sorting mechanisms that direct specific RNAs into subsets of EVs that express specific surface markers.

Tissue-specific immunopathology during malaria infection

Systemic inflammation mediated by Plasmodium parasites is central to malaria disease and its complications. Plasmodium parasites reside in erythrocytes and can theoretically reach all host tissues via the circulation. However, actual interactions between parasitized erythrocytes and host tissues, along with the consequent damage and pathological changes, are limited locally to specific tissue sites. Such tissue specificity of the parasite can alter the outcome of malaria disease, determining whether acute or chronic complications occur. Here, we give an overview of the recent progress that has been made in understanding tissue-specific immunopathology during Plasmodium infection. As knowledge on tissue-specific host-parasite interactions accumulates, better treatment modalities and targets may emerge for intervention in malaria disease.

Engineering mechanical microenvironment of macrophage and its biomedical applications

Macrophages are the most plastic cells in the hematopoietic system and can be widely found in almost all tissues. Recently studies have shown that mechanical cues (e.g., matrix stiffness and stress/strain) can significantly affect macrophage behaviors. Although existing reviews on the physical and mechanical cues that regulate the macrophage's phenotype are available, engineering mechanical microenvironment of macrophages in vitro as well as a comprehensive overview and prospects for their biomedical applications (e.g., tissue engineering and immunotherapy) has yet to be summarized. Thus, this review provides an overview on the existing methods for engineering mechanical microenvironment of macrophages in vitro and then a section on their biomedical applications and further perspectives are presented.

Biomimetic nanoparticles with enhanced affinity towards activated endothelium as versatile tools for theranostic drug delivery

Activation of the vascular endothelium is characterized by increased expression of vascular adhesion molecules and chemokines. This activation occurs early in the progression of several diseases and triggers the recruitment of leukocytes. Inspired by the tropism of leukocytes, we investigated leukocyte-based biomimetic nanoparticles (i.e., leukosomes) as a novel theranostic platform for inflammatory diseases.

Methods: Leukosomes were assembled by combining phospholipids and membrane proteins from leukocytes. For imaging applications, phospholipids modified with rhodamine and gadolinium were used. Leukosomes incubated with antibodies blocking lymphocyte function-associated antigen 1 (LFA-1) and CD45 were administered to explore their roles in targeting inflammation. In addition, relaxometric assessment of NPs was evaluated.

Results: Liposomes and leukosomes were both spherical in shape with sizes ranging from 140-170 nm. Both NPs successfully integrated 8 and 13 µg of rhodamine and gadolinium, respectively, and demonstrated less than 4% variation in physicochemical features. Leukosomes demonstrated a 16-fold increase in breast tumor accumulation relative to liposomes. Furthermore, quantification of leukosomes in tumor vessels demonstrated a 4.5-fold increase in vessel lumens and a 14-fold increase in vessel walls. Investigating the targeting mechanism of action revealed that blockage of LFA-1 on leukosomes resulted in a 95% decrease in tumor accumulation. Whereas blockage of CD45 yielded a 60% decrease in targeting and significant increases in liver and spleen accumulation. In addition, when administered in mice with atherosclerotic plaques, leukosomes exhibited a 4-fold increase in the targeting of inflammatory vascular lesions. Lastly, relaxometric assessment of NPs demonstrated that the incorporation of membrane proteins into leukosomes did not impact the r₁ and r₂ relaxivities of the NPs, demonstrating 6 and 30 mM^-1s^-1, respectively.

Conclusion: Our study demonstrates the ability of leukosomes to target activated vasculature and exhibit superior accumulation in tumors and vascular lesions. The versatility of the phospholipid backbone within leukosomes permits the incorporation of various contrast agents. Furthermore, leukosomes can potentially be loaded with therapeutics possessing diverse physical properties and thus warrant further investigation toward the development of powerful theranostic agents.

Macrophage responses to the physical burden of cell-sized particles

The role of physical burden on macrophage functions was revealed by exploiting an “intake method” and uniform autofluorescent cell-sized particles.

CD47 Blockade as an Adjuvant Immunotherapy for Resectable Pancreatic Cancer

Purpose: Patients with pancreatic ductal adenocarcinoma (PDAC) who undergo surgical resection and adjuvant chemotherapy have an expected survival of only 2 years due to disease recurrence, frequently in the liver. We investigated the role of liver macrophages in progression of PDAC micrometastases to identify adjuvant treatment strategies that could prolong survival.Experimental Design: A murine splenic injection model of hepatic micrometastatic PDAC was used with five patient-derived PDAC tumors. The impact of liver macrophages on tumor growth was assessed by (i) depleting mouse macrophages in nude mice with liposomal clodronate injection, and (ii) injecting tumor cells into nude versus NOD-scid-gamma mice. Immunohistochemistry and flow cytometry were used to measure CD47 ("don't eat me signal") expression on tumor cells and characterize macrophages in the tumor microenvironment. In vitro engulfment assays and mouse experiments were performed with CD47-blocking antibodies to assess macrophage engulfment of tumor cells, progression of micrometastases in the liver and mouse survival.Results:In vivo clodronate depletion experiments and NOD-scid-gamma mouse experiments demonstrated that liver macrophages suppress the progression of PDAC micrometastases. Five patient-derived PDAC cell lines expressed variable levels of CD47. In in vitro engulfment assays, CD47-blocking antibodies increased the efficiency of PDAC cell clearance by macrophages in a manner which correlated with CD47 receptor surface density. Treatment of mice with CD47-blocking antibodies resulted in increased time-to-progression of metastatic tumors and prolonged survival.Conclusions: These findings suggest that following surgical resection of PDAC, adjuvant immunotherapy with anti-CD47 antibody could lead to substantially improved outcomes for patients. Clin Cancer Res; 24(6); 1415-25. ©2017 AACR.