Cranberry extract-based formulations for preventing bacterial biofilms

Generating formulations for the delivery of a mixture of natural compounds extracted from natural sources is a challenge because of unknown active and inactive ingredients and possible interactions between them. As one example, natural cranberry extracts have been proposed for the prevention of biofilm formation on dental pellicle or teeth. However, such extracts may contain phenolic acids, flavonol glycosides along with other constituents like coumaroyl iridoid glycosides, flavonoids, alpha-linolenic acid, n-6 (or n-3) fatty acids, and crude fiber. Due to the presence of a variety of compounds, determining which molecules (and how many molecules) are essential for preventing biofilm growth is nontrivial to ascertain. Therefore, a formulation that could contain natural, unrefined, cranberry extract (with all its constituent compounds) at high loading would be ideal. Accordingly, we have generated several candidate formulations including poly(lactic-co-glycolic) acid (PLGA)-based microencapsulation of cranberry extract (CE15) as well as formulations including stearic acid along with polyvinylpyrrolidone (PVP) or Ethyl lauroyl arginate (LAE) complexed with cranberry extracts (CE15). We found that stearic acid in combination with PVP or LAE as excipients led to higher loading of the active and inactive compounds in CE15 as compared with a PLGA microencapsulation and also sustained release of CE15 in a tunable manner. Using this method, we have been able to generate two successful formulations (one preventative based, one treatment based) that effectively inhibit biofilm growth when incubated with saliva. In addition to cranberry extract, this technique could also be a promising candidate for other natural extracts to form controlled release systems.Graphical abstract.

Metabolite releasing polymers control dendritic cell function by modulating their energy metabolism

Metabolites control immune cell functions, and delivery of these metabolites in a sustained manner may be able to modulate function of the immune cells. In this study, alpha-ketoglutarate (aKG) and diol based polymeric-microparticles (termed paKG MPs) were synthesized to provide sustained release of aKG and promote an immunosuppressive cellular phenotype. Notably, after association with dendritic cells (DCs), paKG MPs modulated the intracellular metabolic-profile/pathways, and decreased glycolysis and mitochondrial respiration in vitro. These metabolic changes resulted in modulation of MHC-II, CD86 expression in DCs, and altered the frequency of regulatory T cells (Tregs), and T-helper type-1/2/17 cells in vitro. This unique strategy of intracellular delivery of key-metabolites in a sustained manner provides a new direction in immunometabolism field-based immunotherapy with potential applications in different diseases associated with immune disorders.

In situ recruitment of regulatory T cells promotes donor-specific tolerance in vascularized composite allotransplantation

Vascularized composite allotransplantation (VCA) encompasses face and limb transplantation, but as with organ transplantation, it requires lifelong regimens of immunosuppressive drugs to prevent rejection. To achieve donor-specific immune tolerance and reduce the need for systemic immunosuppression, we developed a synthetic drug delivery system that mimics a strategy our bodies naturally use to recruit regulatory T cells (T_reg) to suppress inflammation. Specifically, a microparticle-based system engineered to release the T_reg-recruiting chemokine CCL22 was used in a rodent hindlimb VCA model. These "Recruitment-MP" prolonged hindlimb allograft survival indefinitely (>200 days) and promoted donor-specific tolerance. Recruitment-MP treatment enriched T_reg populations in allograft skin and draining lymph nodes and enhanced T_reg function without affecting the proliferative capacity of conventional T cells. With implications for clinical translation, synthetic human CCL22 induced preferential migration of human T_reg in vitro. Collectively, these results suggest that Recruitment-MP promote donor-specific immune tolerance via local enrichment of suppressive T_reg.

3D printing for tissue engineering in otolaryngology

Airway and other head and neck disorders affect hundreds of thousands of patients each year and most require surgical intervention. Among these, congenital deformity that affects newborns is particularly serious and can be life-threatening. In these cases, reconstructive surgery is resolutive but bears significant limitations, including the donor site morbidity and limited available tissue. In this context, tissue engineering represents a promising alternative approach for the surgical treatment of otolaryngologic disorders. In particular, 3D printing coupled with advanced imaging technologies offers the unique opportunity to reproduce the complex anatomy of native ear, nose, and throat, with its import in terms of functionality as well as aesthetics and the associated patient well-being. In this review, we provide a general overview of the main ear, nose and throat disorders and focus on the most recent scientific literature on 3D printing and bioprinting for their treatment.

Azido-Functionalized Polyurethane Designed for Making Tunable Elastomers by Click Chemistry

Polyurethane is an important biomaterial with wide applications in biomedical engineering. Here, we report a new method to make an azido-functionalized polyurethane prepolymer with no need of postmodification. This prepolymer can easily form stable porous elastomers through click chemistry for cross-linking, instead of using a toxic polyisocyanate. The mechanical properties can be modulated by simply adjusting either the prepolymer concentrations or azido/alkyne ratios for cross-linking. Young's modulus therefore varies from 0.52 to 2.02 MPa for the porous elastomers. When the azido-functionalized polyurethane elastomer is made with a compact structure, Young's modulus increases up to 28.8 MPa at 0-15% strain. The strain at break reaches 150% that is comparable to the commercially resourced Nylon-12. Both the porous and compact elastomers could undergo reversible elastic deformations for at least 200 and 1000 cycles, respectively, within 20% strain without failure. The material showed a considerable stability against erosion in a basic solution. In vivo biocompatibility study demonstrated no degradation by subcutaneous implantation in mice over 2 months. The implant induced only a mild inflammatory response and fibrotic capsule. This material might be useful to make elastomeric components of biomedical devices.

A biocompatible betaine-functionalized polycation for coacervation

The aqueous nature of complex coacervates provides a biologically-relevant context for various therapeutic applications. In this sense, biological applications demand a corresponding level of biocompatibility from the polyelectrolytes that participate in complex coacervation. Continued development with naturally-occurring polyelectrolytes such as heparin and chitosan underscore such aims. Herein, we design a synthetic polycation, in which betaine is conjugated to a biodegradable polyester backbone. Betaine is a naturally-occurring methylated amino acid that is ubiquitously present in human plasma. Inspired by its vast range of benefits - including but not limited to anti-inflammation, anti-cancer, anti-bacterial, anti-oxidant, protein stabilization, and cardiovascular health - we aim to impart additional functionality to a polycation for eventual use in a complex coacervate with heparin. We report on its in vitro and in vivo biocompatibility, in vitro and in vivo effect on angiogenesis, in vitro effect on microbial growth, and ability to form complex coacervates with heparin.

TRI Microspheres prevent key signs of dry eye disease in a murine, inflammatory model

Dry eye disease (DED) is a highly prevalent, ocular disorder characterized by an abnormal tear film and ocular surface. Recent experimental data has suggested that the underlying pathology of DED involves inflammation of the lacrimal functional unit (LFU), comprising the cornea, conjunctiva, lacrimal gland and interconnecting innervation. This inflammation of the LFU ultimately results in tissue deterioration and the symptoms of DED. Moreover, an increase of pathogenic lymphocyte infiltration and the secretion of pro-inflammatory cytokines are involved in the propagation of DED-associated inflammation. Studies have demonstrated that the adoptive transfer of regulatory T cells (Tregs) can mediate the inflammation caused by pathogenic lymphocytes. Thus, as an approach to treating the inflammation associated with DED, we hypothesized that it was possible to enrich the body's own endogenous Tregs by locally delivering a specific combination of Treg inducing factors through degradable polymer microspheres (TRI microspheres; TGF-β1, Rapamycin (Rapa), and IL-2). This local controlled release system is capable of shifting the balance of Treg/T effectors and, in turn, preventing key signs of dry eye disease such as aqueous tear secretion, conjunctival goblet cells, epithelial corneal integrity, and reduce the pro-inflammatory cytokine milieu in the tissue.

An Inexpensive, Point-of-Care Urine Test for Bladder Cancer in Patients Undergoing Hematuria Evaluation

Although hematuria (blood in urine) is the most common symptom of bladder cancer, 70-98% of hematuria cases are benign. These hematuria patients unnecessarily undergo costly, invasive, and expensive evaluation for bladder cancer. Therefore, there remains a need for noninvasive office-based tests that can rapidly and reliably rule out bladder cancer in patients undergoing hematuria evaluation. Herein, a clinical assay for matrix metalloproteinases ("Ammps") is presented, which generates a visual signal based on the collagenase activity (in urine of patients) on the Ammps substrates. Ammps substrates are generated by crosslinking gelatin with Fe(II) chelated alginate nanoparticles, which precipitate in urine samples. The cleavage of gelatin-conjugated alginate (Fe(II)) nanoparticles by collagenases generates free-floating alginate (Fe(II)) nanoparticles that participate in Fenton's reaction to generate a visual signal. In a pilot study of 88 patients, Ammps had 100% sensitivity, 85% specificity, and a negative predictive value (NPV) of 100% for diagnosing bladder cancer. This high NPV can be useful in ruling out bladder cancer in patients referred for hematuria evaluation.

Treg-recruiting microspheres prevent inflammation in a murine model of dry eye disease

Dry eye disease (DED) is a common ocular disorder affecting millions of individuals worldwide. The pathology of DED involves the infiltration of CD4+ lymphocytes, leading to tear film instability and destructive inflammation. In the healthy steady state, a population of immunosuppressive T-cells called regulatory T-cells (Treg) regulates proliferation of immune cells that would otherwise lead to a disruption of immunological homeostasis. For this reason, it has been suggested that Tregs could restore the immunological imbalance in DED. To this end, one possible approach would be to recruit the body's own, endogenous Tregs in order to enrich them at the site of inflammation and tissue destruction. Previously, we have demonstrated a reduction of inflammation and disease symptoms in models of periodontitis corresponding to recruitment of endogenous Tregs, which was accomplished by local placement of controlled release systems that sustain a gradient of the chemokine CCL22, referred to here as Treg-recruiting microspheres. Given that DED is characterized by a pro-inflammatory environment resulting in local tissue destruction, we hypothesized that the controlled release of CCL22 could also recruit Tregs to the ocular surface potentially mediating inflammation and symptoms of DED. Indeed, data suggest that Treg-recruiting microspheres are capable of overcoming the immunological imbalance of Tregs and CD4+ IFN-γ+ cells in the lacrimal gland. Administration of Treg-recruiting microspheres effectively mitigated the symptoms of DED as measured through a number of outcomes such as tear clearance, goblet cells density and corneal epithelial integrity, suggesting that recruitment of endogenous Treg can mitigate inflammation associated with DED.

Stapled endosome disrupting alginate particles for cytosolic delivery of cations

Divalent cations, the most prevalent minerals in the body, are responsible for a wide variety of cellular functions including signaling, proliferation, differentiation and cell death, and therefore their transmembrane transportation is tightly regulated. Despite the importance of divalent cations in cell activity, there are currently no intracellular delivery methods for divalent cations or modulation of intracellular levels of minerals. Here, we describe endosome disrupting alginate nanoparticles termed Alginoketals, which can deliver divalent cations to the cytosol of the cells. Alginoketals are generated by crosslinking alginic acid with endosome disrupting ketals, and using divalent cations as the stapling or binding agent. We show that Alginoketals were able to deliver copper (II) in the cytosol of the cancer cells thereby disrupting copper homeostasis and inducing cell death via accumulation of hydrogen peroxide. Alginoketal-copper (II)-based particles act as superoxide dismutase mimics and are the first class of divalent cation delivery vehicles, with potential application in cancer therapy, regenerative medicine and drug delivery.

A cell-based microarray to investigate combinatorial effects of microparticle-encapsulated adjuvants on dendritic cell activation

Experimental vaccine adjuvants are being designed to target specific toll-like receptors (TLRs) alone or in combination, expressed by antigen presenting cells, notably dendritic cells (DCs). There is a need for high-content screening (HCS) platforms to explore how DC activation is affected by adjuvant combinations. Presented is a cell-based microarray approach, "immunoarray", exposing DCs to a large number of adjuvant combinations. Microparticles encapsulating TLR ligands are printed onto arrays in a range of doses for each ligand, in all possible dose combinations. Dendritic cells are then co-localized with physisorbed microparticles on the immunoarray, adherent to isolated islands surrounded by a non-fouling background, and DC activation is quantified. Delivery of individual TLR ligands was capable of eliciting high levels of specific DC activation markers. For example, either TLR9 ligand, CpG, or TLR3 ligand, poly I:C, was capable of inducing among the highest 10% expression levels of CD86. In contrast, MHC-II expression in response to TLR4 agonist MPLA was among the highest, whereas either MPLA or poly I:C, was capable of producing among the highest levels of CCR7 expression, as well as inflammatory cytokine IL-12. However, in order to produce robust responses across all activation markers, adjuvant combinations were required, and combinations were more represented among the high responders. The immunoarray also enables investigation of interactions between adjuvants, and each TLR ligand suggested antagonism to other ligands, for various markers. Altogether, this work demonstrates feasibility of the immunoarray platform to screen microparticle-encapsulated adjuvant combinations for the development of improved and personalized vaccines.

Micro and nanoparticle drug delivery systems for preventing allotransplant rejection

Despite decades of advances in transplant immunology, tissue damage caused by acute allograft rejection remains the primary cause of morbidity and mortality in the transplant recipient. Moreover, the long-term sequelae of lifelong immunosuppression leaves patients at risk for developing a host of other deleterious conditions. Controlled drug delivery using micro- and nanoparticles (MNPs) is an effective way to deliver higher local doses of a given drug to specific tissues and cells while mitigating systemic effects. Herein, we review several descriptions of MNP immunotherapies aimed at prolonging allograft survival. We also discuss developments in the field of biomimetic drug delivery that use MNP constructs to induce and recruit our bodies' own suppressive immune cells. Finally, we comment on the regulatory pathway associated with these drug delivery systems. Collectively, it is our hope the studies described in this review will help to usher in a new era of immunotherapy in organ transplantation.

Stimuli-responsive electrodes detect oxidative stress and liver injury

A digital point-of-care biosensor for measuring reactive oxygen species is presented based on novel reactive oxygen species responsive polymer-based electrodes. The biosensor is able to detect a drug-induced liver injury by monitoring the oxidative stress in the blood.

Epidemiological study of canine parvovirus infection in and around Bhubaneswar, Odisha, India

Aim:

An epidemiological study of canine parvovirus infection in dogs in and around Bhubaneswar, Odisha was conducted between December 2012 to March 2013 and prevalence rate was studied on the basis of age, breed, and sex.

Materials and Methods:

A total of 71 fecal samples from suspected diarrheic dogs were collected in sterile phosphate buffer saline (10% W/V) and examined by polymerase chain reaction (PCR) for detection of canine parvo virus infection, followed by epidemiological study in relation to age, breed, and sex.

Results:

Of 71 samples analyzed, 29 (40.85%) were found to be positive by PCR assay. The infection was higher in Deshi/local breeds (34.48%), followed by German shepherd (17.24%), equal incidences in mixed and Labrador retriever (10.34%), Rottweiler and German spitz showed 6.90% each and finally lower incidences in four breeds (3.45%) such as Dalmatians, Nea politan mastiff, Pug and Great Dane. Age-wise prevalence study revealed the infection being more in the age group of 3-6 months (41.37%), followed by equal incidences of 27.59% in 1-3 months and 6-12 months age group, and a low incidence in age groups above 12 months (3.45%). The incidence was predominantly higher in males (86.21%) than females (13.79%).

Conclusions:

The epidemiological analysis revealed that the breed wise prevalence was found to be more in Deshi breeds as compared to others, age groups below 6 months were found to be more prone to parvovirus infection and males were mostly infected.

VEGF neutralization can prevent and normalize arteriovenous malformations in an animal model for hereditary hemorrhagic telangiectasia 2

Arteriovenous malformation (AVM) refers to a vascular anomaly where arteries and veins are directly connected through a complex, tangled web of abnormal AV fistulae without a normal capillary network. Hereditary hemorrhagic telangiectasia (HHT) types 1 and 2 arise from heterozygous mutations in endoglin (ENG) and activin receptor-like kinase 1 (ALK1), respectively. HHT patients possess AVMs in various organs, and telangiectases (small AVMs) along the mucocutaneous surface. Understanding why and how AVMs develop is crucial for developing therapies to inhibit the formation, growth, or maintenance of AVMs in HHT patients. Previously, we have shown that secondary factors such as wounding are required for Alk1-deficient vessels to develop skin AVMs. Here, we present evidences that AVMs establish from nascent arteries and veins rather than from remodeling of a preexistent capillary network in the wound-induced skin AVM model. We also show that VEGF can mimic the wound effect on skin AVM formation, and VEGF-neutralizing antibody can prevent skin AVM formation and ameliorate internal bleeding in Alk1-deficient adult mice. With topical applications at different stages of AVM development, we demonstrate that the VEGF blockade can prevent the formation of AVM and cease the progression of AVM development. Taken together, the presented experimental model is an invaluable system for precise molecular mechanism of action of VEGF blockades as well as for preclinical screening of drug candidates for epistaxis and gastrointestinal bleedings.

A fluorescent peroxidase probe increases the sensitivity of commercial ELISAs by two orders of magnitude

The low detection sensitivity of enzyme linked immunosorbent assays (ELISAs) is a central problem in science and limits progress in multiple areas of biology and medicine. In this report we demonstrate that the hydrocyanines, a family of fluorescent reactive oxygen species (ROS) probes, can act as turn on fluorescent horseradish peroxidase (HRP) probes and thereby increase the sensitivity of conventional ELISAs by two orders of magnitude.

The effect of cyclic mechanical strain on activation of dendritic cells cultured on adhesive substrates

Dendritic cells (DCs), key regulators of tolerance and immunity, have been found to reside in mechanically active tissues such as the interior layers of the arterial wall, which experience cyclic radial wall strain due to pulsatile blood flow. Although experimentally difficult to determine in vivo, it is reasonable to postulate DCs experience the mechanical forces in such mechanically active tissues. However, it is currently unknown how DCs respond to cyclic mechanical strain. In order to explore the hypothesis that DCs are responsive to mechanical strain, DCs were cultured in vitro on pre-adsorbed adhesive proteins (e.g., laminin, collagen, fibrinogen) and 1 Hz cyclic strain was applied for various durations and strain magnitudes. It was determined that a strain magnitude of 10% and 24 h duration adversely affected DC viability compared to no-strain controls, but culture on certain adhesive substrates provided modest protection of viability under this harsh strain regime. In contrast, application of 1 h of 1 Hz cyclic 3% strain did not affect DC viability and this strain regime was used for the remaining experiments for quantifying DC activation and T-cell priming capability. Application of 3% strain increased expression of stimulatory (MHC-II) and costimulatory molecules (CD86, CD40), and this effect was generally increased by culture on pre-coated adhesive substrates. Interestingly, the cytokine secretion profile of DCs was not significantly affected by strain. Lastly, strained DCs demonstrated increased stimulation of allogeneic T-cell proliferation, in a manner that was independent of the adhesive substrate. These observations indicate generation of a DC consistent with what has been described as a semi-mature phenotype. This work begins elucidating a potential role for DCs in tissue environments exposed to cyclic mechanical forces.

Combinatorial co-encapsulation of hydrophobic molecules in poly(lactide-co-glycolide) microparticles

There is great interest for developing poly(lactide-co-glycolide) (PLGA) based particles for targeted delivery and controlled release of encapsulated biological molecules. These PLGA particles can be used to deliver proteins, small molecule drugs and nucleotides. Furthermore, it has been shown that the co-encapsulation of multiple factors in PLGA particles can generate synergistic responses, and can also provide theranostic capability. However, the number of possible unique particle formulations that may be generated by the combination of different components in a particle increases dramatically with each new component, and currently, there is no method to generate large libraries of unique PLGA particles. In order to address this gap, we have developed a high-throughput methodology to produce hundreds of small batches of particles. The particles are generated in multi-well plate wells by a modified oil-in-water emulsion technique. In order to demonstrate the versatility of this technique, combinatorial formulations of six different loading concentrations of three fluorescent dyes were fabricated giving rise to 216 unique PLGA particle formulations. We demonstrate systematic and well-controlled combinatorial loading of hydrophobic molecules into the particles. This parallel particle production (PPP) methodology potentiates the generation of hundreds of different combinatorial particle formulations with multiple co-encapsulates in less than 24 h in standard polystyrene multi-well plates, thus providing rapid, low cost, high-throughput production. We envision that such a PPP library of particles encapsulating combinations of drugs and imaging modalities can subsequently be tested on small populations of cells in a high-throughput fashion, and represents a step toward personalized medicine.

H-gemcitabine: a new gemcitabine prodrug for treating cancer

In this report, we present a new strategy for targeting chemotherapeutics to tumors, based on targeting extracellular DNA. A gemcitabine prodrug was synthesized, termed H-gemcitabine, which is composed of Hoechst conjugated to gemcitabine. H-gemcitabine has low toxicity because it is membrane-impermeable; however, it still has high tumor efficacy because of its ability to target gemcitabine to E-DNA in tumors. We demonstrate here that H-gemcitabine has a wider therapeutic window than free gemcitabine.

Curcumin prevents corticosterone-induced neurotoxicity and abnormalities of neuroplasticity via 5-HT receptor pathway

Curcumin, a major active component of Curcuma longa, possesses antioxidant and neuroprotective activities. The present study explores the mechanisms underlying the neuroprotective effect of curcumin against corticosterone and its relation to 5-hydroxy tryptamine (5-HT) receptors. Exposure of cortical neurons to corticosterone results in decreased mRNA levels for three 5-HT receptor subtypes, 5-HT(1A), 5-HT(2A) and 5-HT(4), but 5-HT(1B,) 5-HT(2B), 5-HT(2C), 5-HT(6) and 5-HT(7) receptors remain unchanged. Pre-treatment with curcumin reversed this effect on mRNA for the 5-HT(1A) and 5-HT(4) receptors, but not for the 5-HT(2A) receptor. Moreover, curcumin exerted a neuroprotective effect against corticosterone-induced neuronal death. This observed effect of curcumin was partially blocked by either 5-HT(1A) receptor antagonist p-MPPI or 5-HT(4) receptor antagonist RS 39604 alone; whereas, the simultaneous application of both antagonists completely reversed the effect. Curcumin was also found to regulate corticosterone-induced morphological changes such as increases in soma size, dendritic branching and dendritic spine density, as well as elevate synaptophysin expression in cortical neurons. p-MPPI and RS 39604 reversed the effect of curcumin-induced change in neuronal morphology and synaptophysin expression of corticosterone-treated neurons. In addition, an increase in cyclic adenosine monophosphate (cAMP) level was observed after curcumin treatment, which was further prevented by RS 39604, but not by p-MPPI. However, curcumin-induced elevation in protein kinase A activity and phosphorylation of cAMP response element-binding protein levels were inhibited by both p-MPPI and RS 39604. These findings suggest that the neuroprotection and modulation of neuroplasticity exhibited by curcumin might be mediated, at least in part, via the 5-HT receptor-cAMP-PKA-CREB signal pathway.

Adhesive substrates modulate the activation and stimulatory capacity of non-obese diabetic mouse-derived dendritic cells

It is known that adsorbed adhesive proteins on implanted biomaterials modulate inflammatory responses; however, modulation of dendritic cell (DC) responses upon interaction with adhesive proteins has only begun to be characterized. DCs are specialized antigen-presenting cells that modulate both innate and adaptive immune responses. Previously we have shown that the activation and stimulatory capacity of DCs derived from C57BL6/j mice is differentially modulated by adhesive substrates. Here we extend our investigation of adhesive substrate modulation of DC responses to consider the case where the DCs had maturational defects associated with diabetes. Understanding the adhesive responses of DCs in diabetics is potentially important for immunotherapy and tissue engineering applications. In this work we use the non-obese diabetic (NOD) mouse, an established animal model for type 1 diabetes, to generate DCs (NOD-DCs). We demonstrate that NOD-DCs cultured on different adhesive substrates (collagen, fibrinogen, fibronectin, laminin, vitronectin, albumin and serum) respond with substrate-dependent modulation of the surface expression of the stimulatory molecule MHC-II and the co-stimulatory molecules CD80 and CD86 and production of the cytokines IL-12p40 and IL-10. Furthermore, the capacity of NOD-DCs to stimulate CD4(+) T-cell proliferation and cytokine production (IL-4 and IFN-γ) showed substrate-dependent modulation. Specifically, NOD-DCs cultured on vitronectin induced the highest IL-12p40 production, whereas collagen induced the highest IL-10 production. Dendritic cells cultured on collagen, fibrinogen and serum-coated substrates stimulated the highest CD4(+) T-cell proliferation. It was further determined that DCs cultured on vitronectin induced the highest percent population of IL-4-producing T-cells and DCs cultured on a fibronectin-coated substrate induced the highest expression of IFN-γ in T-cells. Pearson's correlation analysis revealed high correlations between T-cell proliferation and DC expression level of CD80 and T-cell production of IL-4 and DC production of IL-10. This demonstration of substrate-based control of NOD-DC activatory and stimulatory capacity, distinct from non-diabetic B6-DC responses, establishes the field of adhesive modulation of immune cell responses and informs the rational design of biomaterials for patients with type 1 diabetes.

Intravital microscopy imaging of macrophage localization to immunogenic particles and co-localized tissue oxygen saturation

Well-designed biomaterial polymer particle-based vaccines will optimally promote immune cell antigen-presenting behavior while minimizing adverse inflammatory responses to the particles and encapsulated drugs or adjuvants. It is important in the design of particle-based vaccines to consider possible harmful effects of immune response on tissue at the vaccination site. Intravital microscopy with rodent dorsal skin window chambers enables in vivo serial observations in the same animal, and such models which have been used to study angiogenesis and macrophage response to implanted biomaterials may also be useful for the development of particle-based vaccines. To our knowledge there have been no reports where intravital microscopy has documented real-time immune cell localization and potentially harmful co-localized tissue effects. In this proof-of-principle study we used fluorescence and spectral imaging intravital microscopy of mouse window chambers to measure macrophage localization and co-localized tissue microvessel hemoglobin saturation changes in response to an immunogenic stimulus from polymer particles loaded with lipopolysaccharide (LPS) serving as a model vaccine/adjuvant system. We observed greater and faster macrophage localization to stronger inflammatory stimuli from LPS-loaded particle doses, a trend of decreased microvessel oxygenation with increased macrophage accumulation and, in an extreme case, complete microvessel collapse accompanied by tissue necrosis. Our technique may be useful for optimizing design of particle-based vaccines and may give insight into the use of hemoglobin saturation as a biomarker of tissue inflammation for clinical investigations of particle-based vaccines.