Intratumoral immunotherapy is an emerging modality for the treatment of solid tumors. Toll-like receptor (TLR) agonists have shown promise for eliciting immune responses, but systemic administration often results in the development of adverse side effects. Herein, we investigate whether localized delivery of the TLR agonist, resiquimod (R848), via platelet membrane-coated nanoparticles (PNP-R848) elicits antitumor responses. The membrane coating provides a means of enhancing interactions with the tumor microenvironment, thereby maximizing the activity of R848. Intratumoral administration of PNP-R848 strongly enhances local immune activation and leads to complete tumor regression in a colorectal tumor model, while providing protection against repeated tumor re-challenges. Moreover, treatment of an aggressive breast cancer model with intratumoral PNP-R848 delays tumor growth and inhibits lung metastasis. Our findings highlight the promise of locally delivering immunostimulatory payloads using biomimetic nanocarriers, which possess advantages such as enhanced biocompatibility and natural targeting affinities.

Development of theranostic nano-constructs may enable diagnosis and treatment of diseases at high spatial resolution. Some key requirements for clinical translation of such constructs are that they must be non-toxic, non-immunogenic, biodegradable, with extended circulating lifetime. Cell-based structures, particularly those derived from erythrocytes, are promising candidate carrier systems to satisfy these requirements. One particular type of theranostic materials utilize light-sensitive agents that once photo-activated can provide diagnostic imaging capability, and elicit therapeutic effects. Here we demonstrate the first successful engineering of hybrid nano-scale constructs derived from membranes of hemoglobin-depleted erythrocytes that encapsulate the near infrared chromophore, indocyanine green. We show the utility of the constructs as photo-theranostic agents in fluorescence imaging and photothermal destruction of human cells. These erythrocyte-mimicking nano-structures can be derived autologously, and may have broad applications in personal nanomedicine ranging from imaging and photo-destruction of cancerous tissues to vascular abnormalities, and longitudinal evaluations of therapeutic interventions.

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This article describes the development and the examination of surface coatings that suppress the adhesion between glass surfaces and polymer microspheres. Superparamagnetic doping allowed for exerting magnetic forces on the microbeads. The carboxyl functionalization of the polymer provided the means for coating the beads with polyethylene glycol (PEG) with different molecular weight. Under gravitational force, the microbeads settled on glass surfaces with similar polymer coatings. We examined the efficacy of removing the beads from the glass surfaces by applying a pulling force of ~1.2 pN. The percent beads remaining on the surface after applying the pulling force for approximately 5 s served as an indication of the adhesion propensity. Coating of PEG with molecular weight ranging between 3 and 10 kDa was essential for suppressing the adhesion. For the particular substrates, surface chemistry and aqueous media we used, coatings of 5 kDa manifested optimal suppression of adhesion: that is, only 3% of the microbeads remained on the surface after applying the pulling magnetic force. When either the glass or the beads were not PEGylated, the adhesion between them was substantial. Addition of a noncharged surfactant, TWEEN, above its critical micelle concentrations (CMCs) suppressed the adhesion between noncoated substrates. The extent of this surfactant-induced improvement of the adhesion suppression, however, did not exceed the quality of preventing the adhesion that we attained by PEGylating both substrates. In addition, the use of surfactants did not significantly improve the suppression of bead-surface adhesion when both substrates were PEGylated. These findings suggest that such surfactant additives tend to be redundant and that covalently grafted coatings of PEGs with selected chain lengths provide sufficient suppression of nonspecific interfacial interactions.

Near-infrared (NIR) optically active nanoparticles are promising exogenous chromophores for applications in medical imaging and phototherapy. Since nanoparticles can be rapidly eliminated from the body by cells of the reticuloendothelial system, a thriving strategy to increase their blood circulation time is through surface modification with polyethylene glycol (PEG). We constructed polymeric nanocapsules loaded with indocyanine green (ICG), an FDA-approved NIR dye, and coated with aldehyde-terminated PEG. Using optical absorbance spectroscopy and flow cytometry, we investigated the effect of PEG coating and molecular weight (MW) of PEG [5000 and 30,000 Daltons (Da)] on the phagocytic content of human spleen macrophages incubated with ICG-containing nanocapsules (ICG-NCs) between 15 to 360 min. Our results indicate that surface coating with PEG is an effective method to reduce the phagocytic content of ICG-NCs within macrophages for at least up to 360 min of incubation time. Coating the surface of ICG-NCs with the low MW PEG results in lower phagocytic content of ICG-NCs within macrophages for at least up to 60 min of incubation time as compared to ICG-NCs coated with the high MW PEG. Surface coating of ICG-NCs with PEG is a promising approach to prolong vasculature circulation time of ICG for NIR imaging and phototherapeutic applications.

Background and Objectives: Ovarian cancer remains the deadliest malignancy of the female reproductive system. The ability to identify and destroy all ovarian tumor nodules may have a termendous impact on preventing tumor recurrence, and patient survival. The objective of this study is to investigate the effectiveness of a nano-structured system for combined near infrared (NIR) fluorescence imaging of human epidermal growth factor receptor-2 (HER2) over-expression, as a biomarker of ovarian cancer cells, and photothermal destruction of these cells in vitro. Materials and Methods: The nano-structured system consists of the near infrared dye, indocyanine green (ICG), encapsulated within poly(allylamine) hydrochloride chains cross-linked ionically with sodium phosphate. The surface of the construct is functionalized by covalently attached polyethylene glycol, and monoclonal antibodies against HER2 using reducitve amination methods. We use dynamic light scattering, and absorption and fluorescence spectroscopy for phyiscal characterization of the constructs. Flow cytometry and fluorescence microscopy are used to investigate molecular targeting and imaging capabilities of the constructs against SKOV3 and OVCAR3 ovarian cancer cell lines, which have relatively high and low expression levels of the HER2 receptor, respectively. Continuous NIR laser irradiation at 808 nm is used to investigating the utility of the constructs in mediating photothermal destruction of SKOV3 cells. Results: Flow cytometry results indicate that the functionalized nano-constructs are more effective in targeting the HER2 receptor than non-encapsulated ICG and non-functionlaized constructs (P < 0.005). Fluorescence microscopic images show the capaiblity of the functionalized constructs in NIR imaging of HER2 overexpression. The functionalized nano-constructs are also capable of inducing a significantly greater increase in photothermal destruction of SKOV3 cells than free ICG and non-functionalized constructs (P < 0.005). Conclusion: We have demonstrated the efficacy of polymeric nano-structured constructs loaded with ICG, and functionalized with the monoclonal antibodies, as thernaostic materials for targted molecular NIR imaging of the HER2 receptor overexpression on ovarian cancer cells, and photothermal destruction of these cells. These nanoparticles may prove useful towards intraoperative detection, imaging, and phototherapy of small ovarian cancer nodules.

Ischemia reperfusion injury (IRI) evokes intra-graft inflammatory responses, which markedly augment alloimmune responses against the graft. Understanding the mechanisms underlying these responses is fundamental to develop therapeutic regimens to prevent/ameliorate organ IRI. Here, we demonstrate that IRI results in a marked increase in mitochondrial damage and autophagy in dendritic cells (DC). While autophagy is a survival mechanism for ischemic DC, it also augments their production of IL6. Allograft derived dendritic cells (ADDC) lacking autophagy related gene 5 (Atg5) showed higher death rates post-transplantation. Transplanted ischemic hearts from CD11cCre/Atg5 conditional knockout mice showed marked reduction in intra-graft expression of IL6 as compared to controls. To antagonize the effect of IL6 locally in the heart, we synthesized novel anti-IL6 nanoparticles with capacity for controlled release of anti-IL6 over time. As compared to systemic delivery of anti-IL6, localized delivery of anti-IL6 significantly reduced chronic rejection with a markedly lower amount administered. Despite improved allograft histology, there were no changes to splenic T cell populations, illustrating the importance of local IL6 in driving chronic rejection after IRI. These data carry potential clinical significance, by identifying an innovative, targeted strategy to manipulate organs prior to transplantation to diminish inflammation, leading to improved long term outcomes.