Increasing TNF levels solely in the rat hippocampus produces persistent pain-like symptoms

The manifestation of chronic, neuropathic pain includes elevated levels of the cytokine tumor necrosis factor-alpha (TNF). Previously, we have shown that the hippocampus, an area of the brain most notable for its role in learning and memory formation, plays a fundamental role in pain sensation. Using an animal model of peripheral neuropathic pain, we have demonstrated that intracerebroventricular infusion of a TNF antibody adjacent to the hippocampus completely alleviated pain. Furthermore, intracerebroventricular infusion of rTNF adjacent to the hippocampus induced pain behavior in naïve animals similar to that expressed during a model of neuropathic pain. These data support our premise that enhanced production of hippocampal-TNF is integral in pain sensation. In the present study, TNF gene expression was induced exclusively in the hippocampus, eliciting increased local bioactive TNF levels, and animals were assessed for pain behaviors. Male Sprague-Dawley rats received stereotaxic injection of gold nanorod (GNR)-complexed cDNA (control or TNF) plasmids (nanoplasmidexes), and pain responses (i.e., thermal hyperalgesia and mechanical allodynia) were measured. Animals receiving hippocampal microinjection of TNF nanoplasmidexes developed thermal hyperalgesia bilaterally. Sensitivity to mechanical stimulation also developed bilaterally in the rat hind paws. In support of these behavioral findings, immunoreactive staining for TNF, bioactive levels of TNF, and levels of TNF mRNA per polymerase chain reaction analysis were assessed in several brain regions and found to be increased only in the hippocampus. These findings indicate that the specific elevation of TNF in the hippocampus is not a consequence of pain, but in fact induces these behaviors/symptoms.

In situ gold nanoparticles formation: contrast agent for dental optical coherence tomography

In this work we demonstrate the potential use of gold nanoparticles as contrast agents for the optical coherence tomography (OCT) imaging technique in dentistry. Here, a new in situ photothermal reduction procedure was developed, producing spherical gold nanoparticles inside dentinal layers and tubules. Gold ions were dispersed in the primer of commercially available dental bonding systems. After the application and permeation in dentin by the modified adhesive systems, the dental bonding materials were photopolymerized concurrently with the formation of gold nanoparticles. The gold nanoparticles were visualized by scanning electron microscopy (SEM). The SEM images show the presence of gold nanospheres in the hybrid layer and dentinal tubules. The diameter of the gold nanoparticles was determined to be in the range of 40 to 120 nm. Optical coherence tomography images were obtained in two- and three-dimensions. The distribution of nanoparticles was analyzed and the extended depth of nanosphere production was determined. The results show that the OCT technique, using in situ formed gold nanoparticles as contrast enhancers, can be used to visualize dentin structures in a non-invasive and non-destructive way.

Noninvasive real-time fluorescence imaging of the lymphatic uptake of BSA-IRDye 680 conjugate administered subcutaneously in mice

The goal of our studies was to determine lymphatic uptake of bovine serum albumin (BSA) using real-time noninvasive fluorescence imaging. BSA labeled with near-infrared dye (IRDye) 680 was used as a model protein-dye conjugate. The conjugation of BSA with IRDye 680 was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Size-exclusion high-performance liquid chromatography and SDS-PAGE demonstrated that the IRDye 680-labeled BSA conjugate in the lymph node (LN) homogenate samples was stable at physiological temperature (37°C) for at least 5 days. Whole-body noninvasive optical imaging of hairless SKH-1 mice was performed after subcutaneous (s.c.) injection (dose = 0.1 mg/kg) into the front footpad. Noninvasive fluorescence imaging demonstrated that BSA-IRDye 680 conjugates were dynamically taken up by the lymphatic system, accumulated in the axillary LNs and then cleared, indicating that lymphatic transport plays a role in the absorption of BSA. Ex vivo tissue imaging of LN homogenates provided confirmatory data with respect to the uptake of fluorescent-labeled BSA determined by in vivo imaging. Noninvasive real-time imaging of LNs provides a novel tool for evaluating uptake and accumulation of fluorescent-labeled proteins by the lymphatic system after s.c. injection in a mouse model.

Organically modified silica nanoparticles are biocompatible and can be targeted to neurons in vivo

The application of nanotechnology in biological research is beginning to have a major impact leading to the development of new types of tools for human health. One focus of nanobiotechnology is the development of nanoparticle-based formulations for use in drug or gene delivery systems. However most of the nano probes currently in use have varying levels of toxicity in cells or whole organisms and therefore are not suitable for in vivo application or long-term use. Here we test the potential of a novel silica based nanoparticle (organically modified silica, ORMOSIL) in living neurons within a whole organism. We show that feeding ORMOSIL nanoparticles to Drosophila has no effect on viability. ORMOSIL nanoparticles penetrate into living brains, neuronal cell bodies and axonal projections. In the neuronal cell body, nanoparticles are present in the cytoplasm, but not in the nucleus. Strikingly, incorporation of ORMOSIL nanoparticles into the brain did not induce aberrant neuronal death or interfered with normal neuronal processes. Our results in Drosophila indicate that these novel silica based nanoparticles are biocompatible and not toxic to whole organisms, and has potential for the development of long-term applications.

Gold nanorod--siRNA induces efficient in vivo gene silencing in the rat hippocampus

AIM

Gold nanorods (GNRs), cellular imaging nanoprobes, have been used for drug delivery therapy to immunologically privileged regions in the brain. We demonstrate that nanoplexes formed by electrostatic binding between negatively charged RNA and positively charged GNRs, silence the expression of the target housekeeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH) within the CA1 hippocampal region of the rat brain, without showing cytotoxicity.

MATERIALS & METHODS

Fluorescence imaging with siRNA(Cy3)GAPDH and dark-field imaging using plasmonic enhanced scattering from GNRs were used to monitor the distribution of the nanoplexes within different neuronal cell types present in the targeted hippocampal region.

RESULTS & CONCLUSION

Our results show robust nanoplex uptake and slow release of the fluorescent gene silencer with significant impact on the suppression of GAPDH gene expression (70% gene silencing, >10 days postinjection). The observed gene knockdown using nanoplexes in targeted regions of the brain opens a new era of drug treatment for neurological disorders.

Suppression of MMP-9 expression in brain microvascular endothelial cells (BMVEC) using a gold nanorod (GNR)-siRNA nanoplex

Inhibition of Matrix metalloproteinase-9 (MMP-9) activity using delivery of short interfering RNA (siRNA) molecules to brain microvascular endothelial cells (BMVECs) that constitute the BBB may have a significant impact on reducing the BBB permeability. Gold nano rods (GNRs) can electrostatically bind with MMP-9 siRNA to form a nanoplex and the uptake of this nanoplex by BMVEC cells can result in suppression of MMP-9 expression. The current study explores if this GNR-MMP-9 siRNA nanoplex gene silencing modulates the expression of tight junction (TJ) proteins in the BMVEC. The endothelial TJ's of the BBB play a critical role in controlling cellular traffic into the central nervous system. We hypothesize that silencing of the MMP-9 gene expression in BMVEC will increase the expression of TJ proteins thereby decrease endothelial permeability. Our results showed a significant increase in the gene and protein expression of TJ proteins: ZO-1, Occludin and Claudin-5 in BMVEC cells that were transfected with the GNRs-siRNA-MMP-9 nanoplex suggesting that BBB disruption, which results from loss of TJ function due to MMP-9 activation during neuroinflammation can be prevented by silencing MMP-9 expression.

WITHDRAWN: Synthesis and Characterization of Anticancer Drug and Antibody conjugated Quantum Dots as A Novel Theranostic Probe for Pancreatic Cancer Detection and Therapy

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Nanotherapeutics Using an HIV-1 Poly A and Transactivator of the HIV-1 LTR-(TAR-) Specific siRNA

HIV-1 replication can be efficiently inhibited by intracellular expression of an siRNA targeting the viral RNA. We used a well-validated siRNA (si510) which targets the poly A/TAR (transactivator of the HIV-1 LTR) site and suppresses viral replication. Nanotechnology holds much potential for impact in the field of HIV-1 therapeutics, and nanoparticles such as quantum rods (QRs) can be easily functionalized to incorporate siRNA forming stable nanoplexes that can be used for gene silencing. We evaluated the efficacy of the QR-si510 HIV-1 siRNA nanoplex in suppressing viral replication in the HIV-1-infected monocytic cell line THP-1 by measuring p24 antigen levels and gene expression levels of HIV-1 LTR. Our results suggest that the QR-si510 HIV-1 siRNA nanoplex is not only effective in delivering siRNA, but also in suppressing HIV-1 viral replication for a longer time period. HIV-1 nanotherapeutics can thus enhance systemic bioavailability and offer multifunctionality.

Bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles as novel tumor targeting carriers

In this study, we have developed a novel carrier, micelle-type bioconjugated PLGA-4-arm-PEG branched polymeric nanoparticles (NPs), for the detection and treatment of pancreatic cancer. These NPs contained 4-arm-PEG as corona, and PLGA as core, the particle surface was conjugated with cyclo(arginine-glycine-aspartate) (cRGD) as ligand for in vivo tumor targeting. The hydrodynamic size of the NPs was determined to be 150-180 nm and the critical micellar concentration (CMC) was estimated to be 10.5 mg l( - 1). Our in vitro study shows that these NPs by themselves had negligible cytotoxicity to human pancreatic cancer (Panc-1) and human glioblastoma (U87) cell lines. Near infrared (NIR) microscopy and flow cytometry demonstrated that the cRGD conjugated PLGA-4-arm-PEG polymeric NPs were taken up more efficiently by U87MG glioma cells, over-expressing the α(v)β(3) integrin, when compared with the non-targeted NPs. Whole body imaging showed that the cRGD conjugated PLGA-4-arm-PEG branched polymeric NPs had the highest accumulation in the pancreatic tumor site of mice at 48 h post-injection. Physical, hematological, and pathological assays indicated low in vivo toxicity of this NP formulation. These studies on the ability of these bioconjugated PLGA-4-arm-PEG polymeric NPs suggest that the prepared polymeric NPs may serve as a promising platform for detection and targeted drug delivery for pancreatic cancer.

Non-invasive tumor detection in small animals using novel functional Pluronic nanomicelles conjugated with anti-mesothelin antibody

In this study QDs were encapsulated in carboxylated PluronicF127 (F127COOH) triblock polymeric micelles and conjugated with anti-mesothelin antibody for the purpose of alleviating potential toxicity, enhancing the stability and improving targeting efficiency of CdTe/ZnS quantum dots (QDs) in tumors. The amphiphilic triblock polymer of F127COOH contains hydrophilic carboxylated poly(ethylene oxide) (PEO) and hydrophobic poly(propylene oxide) (PPO) units. After encapsulating QDs into carboxylated F127 (F127COOH-QD) micelles, the particles were conjugated with anti-mesothelin antibodies to allow targeting of cancerous areas. The size of the monodispersed spherical QD-containing micelles was determined to be ∼120 nm by dynamic light scattering (DLS). The critical micelle concentration (CMC) was estimated to be 4.7 × 10(-7) M. In an in vitro study, the anti-methoselin antibody conjugated F127COOH (Me-F127COOH-QD) nanomicelles showed negligible cytotoxicity to pancreatic cancer cells (Panc-1). Confocal microscopy demonstrated that the Me-F127COOH-QD nanomicelles were taken up more efficiently by Panc-1 cells, due to antibody mediated targeting. An in vivo imaging study showed that Me-F127COOH-QD nanomicelles accumulated at the pancreatic tumor site 15 min after intravenous injection. In addition, the low in vivo toxicity of the nanomicellar formulation was evaluated by pathological assays. These results suggest that anti-mesothein antibody conjugated carboxylated F127 nanomicelles may serve as a promising nanoscale platform for early human pancreatic cancer detection and targeted drug delivery.

Biocompatible PEGylated gold nanorods as colored contrast agents for targeted in vivo cancer applications

In this contribution, we report the use of a PEGylated gold nanorods formulation as a colored dye for tumor labeling in vivo. We have demonstrated that the nanorod-targeted tumor site can be easily differentiated from the background tissues by the 'naked eye' without the need of sophisticated imaging instruments. In addition to tumor labeling, we have also performed in vivo toxicity and biodistribution studies of PEGylated gold nanorods in vivo by using BALB/c mice as the model. In vivo toxicity studies indicated no mortality or adverse effects or weight changes in BALB/c mice treated with PEGylated gold nanorods. This finding will provide useful guidelines in the future development of diagnostic probes for cancer diagnosis, optically guided tumor surgery, and lymph node mapping applications.

Gold nanorod delivery of an ssRNA immune activator inhibits pandemic H1N1 influenza viral replication

The emergence of the pandemic 2009 H1N1 influenza virus has become a world-wide health concern. As drug resistance appears, a new generation of therapeutic strategies will be required. Here, we introduce a nanotechnology approach for the therapy of pan-demic and seasonal influenza virus infections. This approach uses gold nanorods (GNRs) to deliver an innate immune activator, pro-ducing a localized therapeutic response. We demonstrated the utility of a biocompatible gold nanorod, GNR-5'PPP-ssRNA nanoplex, as an antiviral strategy against type A influenza virus. In human respiratory bronchial epithelial cells, this nanoplex activated the retinoic acid-inducible gene I (RIG-I) pathogen recognition pathway, resulting in increased expression of IFN-beta and other IFN-stimulated genes (ISGs) (e.g., PKR, MDA5, IRF1, IRF7, and MX1). This increase in type I IFN and ISGs resulted in a decrease in the replication of H1N1 influenza viruses. These findings suggest that further evaluation of biocompatible nanoplexes as unique antivirals for treatment of seasonal and pandemic influenza viruses is warranted.

Functionalized near-infrared quantum dots for in vivo tumor vasculature imaging

In this paper, we report the use of near-infrared (NIR)-emitting alloyed quantum dots (QDs) as efficient optical probes for high contrast in vivo imaging of tumors. Alloyed CdTe(1 - x)Se(x)/CdS QDs were prepared in the non-aqueous phase using the hot colloidal synthesis approach. Water dispersion of the QDs were accomplished by their encapsulation within polyethyleneglycol (PEG)-grafted phospholipid micelles. For tumor-specific delivery in vivo, the micelle-encapsulated QDs were conjugated with the cyclic arginine-glycine-aspartic acid (cRGD) peptide, which targets the alpha(v)beta(3) integrins overexpressed in the angiogenic tumor vasculatures. Using in vivo NIR optical imaging of mice bearing pancreatic cancer xenografts, implanted both subcutaneously and orthotopically, we have demonstrated that systemically delivered cRGD-conjugated QDs, but not the unconjugated ones, can efficiently target and label the tumors with high signal-to-noise ratio. Histopathological analysis of major organs of the treated mice showed no evidence of systemic toxicity associated with these QDs. These experiments suggest that cRGD-conjugated NIR QDs can serve as safe and efficient probes for optical bioimaging of tumors in vivo. Furthermore, by co-encapsulating these QDs and anticancer drugs within these micelles, we have demonstrated a promising theranostic, nanosized platform for both cancer imaging and therapy.

In vivo biodistribution and clearance studies using multimodal organically modified silica nanoparticles

Successful translation of the use of nanoparticles from laboratories to clinics requires exhaustive and elaborate studies involving the biodistribution, clearance, and biocompatibility of nanoparticles for in vivo biomedical applications. We report here the use of multimodal organically modified silica (ORMOSIL) nanoparticles for in vivo bioimaging, biodistribution, clearance, and toxicity studies. We have synthesized ORMOSIL nanoparticles with diameters of 20-25 nm, conjugated with near-infrared (NIR) fluorophores and radiolabeled them with (124)I, for optical and PET imaging in vivo. The biodistribution of the nontargeted nanoparticles was studied in nontumored nude mice by optical fluorescence imaging, as well by measuring the radioactivity from harvested organs. Biodistribution studies showed a greater accumulation of nanoparticles in liver, spleen, and stomach than in kidney, heart, and lungs. The clearance studies carried out over a period of 15 days indicated hepatobiliary excretion of the nanoparticles. Selected tissues were analyzed for any potential toxicity by histological analysis, which confirmed the absence of any adverse effect or any other abnormalities in the tissues. The results demonstrate that these multimodal nanoparticles have potentially ideal attributes for use as biocompatible probes for in vivo imaging.

Synthesis of ternary CuInS(2)/ZnS quantum dot bioconjugates and their applications for targeted cancer bioimaging

This contribution introduces the use of cadmium-free CuInS(2) quantum dots (QDs) for targeted and multiplexed optical imaging of tumors in mice. CuInS(2)/ZnS QDs were synthesized in a non-aqueous phase using the hot colloidal synthesis method. Previous challenges involving stable aqueous dispersion of highly luminescent CuInS(2)/ZnS QDs have been overcome by encapsulating them within functionalized phospholipid micelles, which also facilitated their conjugation with folic acid for targeted delivery. Luminescence signals of QDs of multiple colors were readily differentiated from background autofluorescence in whole animal optical imaging. In addition, two-photon excitation studies revealed that the prepared water-dispersible QDs are suitable for two-photon in vitro and in vivo imaging. This study demonstrates the important key steps in realizing of the potential of CuInS(2) QDs as low-toxicity, photostable, cadmium-free and highly luminescent probes for cancer detection and sensing.

Biocompatible near-infrared quantum dots as ultrasensitive probes for long-term in vivo imaging applications

A facile synthesis method to produce monodisperse, biocompatible, lysine crosslinked mercaptoundecanoic acid (MUA) CdSe(0.25)Te(0.75)/CdS near-infrared (NIR) quantum dots and use them as probes to study their long term in vivo distribution, clearance, and toxicity is presented. Large signal enhancements are demonstrated by these quantum dots, which enables their use as efficient and sensitive probes for live-animal imaging. An important finding is that mice intravenously injected with approximately 10.5 mg kg(-1) of NIR QDs survive for more than three months without any apparent adverse effect to their health. Furthermore, it is determined that there is a significant reduction in the number of the QDs in the liver and spleen three months post injection. In addition, histological analysis of heart, kidney, liver, spleen, and lung tissue indicates that there are no acute toxic effects from these lysine cross-linked MUA NIR QDs. This study suggests that these NIR QDs can be potentially used for long-term targeted imaging and therapy studies in vivo.

MMP-9 gene silencing by a quantum dot-siRNA nanoplex delivery to maintain the integrity of the blood brain barrier

The matrix-degrading metalloproteinases (MMPs), particularly MMP-9, are involved in the neuroinflammation processes leading to disrupting of the blood brain barrier (BBB), thereby exacerbating neurological diseases such as HIV-1 AIDS dementia and cerebral ischemia. Nanoparticles have been proposed to act as non-viral gene delivery vectors and have great potential for therapeutic applications in several disease states. In this study, we evaluated the specificity and efficiency of quantum dot (QD) complexed with MMP-9-siRNA (nanoplex) in downregulating the expression of MMP-9 gene in brain microvascular endothelial cells (BMVEC) that constitute the BBB. We hypothesize that silencing MMP-9 gene expression in BMVECs and other cells such as leukocytes may help prevent breakdown of the BBB and inhibit subsequent invasion of the central nervous system (CNS) by infected and inflammatory cells. Our results show that silencing of MMP-9 gene expression resulted in the up-regulation of extracellular matrix (ECM) proteins like collagen I, IV, V and a decrease in endothelial permeability, as reflected by reduction of transendothelial resistance across the BBB in a well validated in-vitro BBB model. MMP-9 gene silencing also resulted in an increase in expression of the gene tissue inhibitor of metalloproteinase-1 (TIMP-1). This indicates the importance of a balance between the levels of MMP-9 and its natural inhibitor TIMP-1 in maintaining the basement membrane integrity. These studies promise the application of a novel nanoparticle based siRNA delivery system in modulating the MMP-9 activity in BMVECs and other MMP-9 producing cells. This will prevent neuroinflammation and maintain the integrity of the BBB.

Imaging pancreatic cancer using bioconjugated InP quantum dots

In this paper, we report the successful use of non-cadmium-based quantum dots (QDs) as highly efficient and nontoxic optical probes for imaging live pancreatic cancer cells. Indium phosphide (core)-zinc sulfide (shell), or InP/ZnS, QDs with high quality and bright luminescence were prepared by a hot colloidal synthesis method in nonaqueous media. The surfaces of these QDs were then functionalized with mercaptosuccinic acid to make them highly dispersible in aqueous media. Further bioconjugation with pancreatic cancer specific monoclonal antibodies, such as anticlaudin 4 and antiprostate stem cell antigen (anti-PSCA), to the functionalized InP/ZnS QDs, allowed specific in vitro targeting of pancreatic cancer cell lines (both immortalized and low passage ones). The receptor-mediated delivery of the bioconjugates was further confirmed by the observation of poor in vitro targeting in nonpancreatic cancer based cell lines which are negative for the claudin-4-receptor. These observations suggest the immense potential of InP/ZnS QDs as non-cadmium-based safe and efficient optical imaging nanoprobes in diagnostic imaging, particularly for early detection of cancer.

Tumor targeting and imaging in live animals with functionalized semiconductor quantum rods

In this contribution, we demonstrate that highly luminescent CdSe/CdS/ZnS quantum rods (QRs) coated with PEGylated phospholipids and conjugated with cyclic RGD peptide can be successfully used for tumor targeting and imaging in live animals. The design of these targeted luminescent probes involves encapsulation of hydrophobic CdSe/CdS/ZnS QRs with PEGylated phospholipids, followed by conjugation of these PEGylated phospholipids to ligands that specifically target the tumor vasculature. In vivo optical imaging studies in nude mice bearing pancreatic cancer xenografts, both subcutaneous and orthotopic, indicate that the QR probes accumulate at tumor sites via the cyclic RGD peptides on the QR surface binding to the alpha(V)beta(3) integrins overexpressed in the tumor vasculature, following systemic injection. In vivo tumor detection studies showed no adverse effects even at a dose roughly 6.5 times higher than has been reported for in vivo imaging studies using quantum dots. Cytotoxicity studies indicated the absence of any toxic effect in the cellular and tissue levels arising from functionalized QRs. These results demonstrate the vast potential of QRs as bright, photostable, and biocompatible luminescent probes for the early diagnosis of cancer.

High contrast in vitro and in vivo photoluminescence bioimaging using near infrared to near infrared up-conversion in Tm3+ and Yb3+ doped fluoride nanophosphors

A new approach for photoluminescence imaging in vitro and in vivo has been shown utilizing near infrared to near infrared (NIR-to-NIR) up-conversion in nanophosphors. This NIR-to-NIR up-conversion process provides deeper light penetration into biological specimen and results in high contrast optical imaging due to absence of an autofluorescence background and decreased light scattering. Aqueous dispersible fluoride (NaYF4) nanocrystals (20-30 nm size) co-doped with the rare earth ions, Tm(3+) and Yb(3+), were synthesized and characterized by TEM, XRD, and photoluminescence (PL) spectroscopy. In vitro cellular uptake was shown by the PL microscopy visualizing the characteristic emission of Tm(3+) at approximately 800 nm excited with 975 nm. No apparent cytotoxicity was observed. Subsequent animal imaging studies were performed using Balb-c mice injected intravenously with up-converting nanophosphors, demonstrating the high contrast PL imaging in vivo.

Nonviral gene transfection nanoparticles: function and applications in the brain

In vivo transfer and expression of foreign genes allows for the elucidation of functions of genes in living organisms and generation of disease models in animals that more closely resemble the etiology of human diseases. Gene therapy holds promise for the cure of a number of diseases at the fundamental level. Synthetic "nonviral" materials are fast gaining popularity as safe and efficient vectors for delivering genes to target organs. Not only can nanoparticles function as efficient gene carriers, they also can simultaneously carry diagnostic probes for direct "real-time" visualization of gene transfer and downstream processes. This review has focused on the central nervous system (CNS) as the target for nonviral gene transfer, with special emphasis on organically modified silica (ORMOSIL) nanoparticles developed in our laboratory. These nanoparticles have shown robust gene transfer efficiency in brain cells in vivo and allowed to investigate mechanisms that control neurogenesis as well as neurodegenerative disorders.

Covalently dye-linked, surface-controlled, and bioconjugated organically modified silica nanoparticles as targeted probes for optical imaging

In this paper we report the synthesis and characterization of organically modified silica (ORMOSIL) nanoparticles, covalently incorporating the fluorophore rhodamine-B, and surface-functionalized with a variety of active groups. The synthesized nanoparticles are of ultralow size (diameter approximately 20 nm), highly monodispersed, stable in aqueous suspension, and retain the optical properties of the incorporated fluorophore. The surface of the nanoparticles can be functionalized with a variety of active groups such as hydroxyl, thiol, amine, and carboxyl. The carboxyl groups on the surface were used to conjugate with various bioactive molecules such as transferrin, as well as monoclonal antibodies such as anti-claudin 4 and anti-mesothelin, for targeted delivery to pancreatic cancer cell lines. In vitro experiments have revealed that the cellular uptake of these bioconjugated (targeted) nanoparticles is significantly higher than that of the nonconjugated ones. The ease of surface functionalization and incorporation of a variety of biotargeting molecules, combined with their observed noncytotoxicity, makes these fluorescent ORMOSIL nanoparticles potential candidates as efficient probes for optical bioimaging, both in vitro and in vivo.

Organically modified silica nanoparticles with covalently incorporated photosensitizer for photodynamic therapy of cancer

We report a novel nanoformulation of a photosensitizer (PS), for photodynamic therapy (PDT) of cancer, where the PS molecules are covalently incorporated into organically modified silica (ORMOSIL) nanoparticles. We found that the covalently incorporated PS molecules retained their spectroscopic and functional properties and could robustly generate cytotoxic singlet oxygen molecules upon photoirradiation. The synthesized nanoparticles are of ultralow size ( approximately 20 nm) and are highly monodispersed and stable in aqueous suspension. The advantage offered by this covalently linked nanofabrication is that the drug is not released during systemic circulation, which is often a problem with physical encapsulation. These nanoparticles are also avidly uptaken by tumor cells in vitro and demonstrate phototoxic action, thereby highlighting their potential in diagnosis and PDT of cancer.

ORMOSIL nanoparticles as a non-viral gene delivery vector for modeling polyglutamine induced brain pathology

Studies have shown the presence of expanded polyQ containing proteins in brain cells related to Huntington disease (HD) and other poly-glutamine disorders. We report the use of organically modified silica (ORMOSIL) nanoparticles as an efficient non-viral gene carrier in an effort to model brain pathology associated with those disorders induced by expanded polyQ peptides. In experiment 1, plasmids expressing Hemaglutinin-tagged polypeptides with 20 glutamine repeats (Q20) or with extended 127-glutamine repeats (Q127) were complexed with ORMOSIL nanoparticles and injected twice (2 weeks apart) into the lateral ventricle of the mouse brain. Fourteen days post-injection of Q127, immunocytochemistry revealed the presence of the characteristic nuclear and cytoplasmic Q127 aggregates in numerous striatal, septal and neocortical neuronal cells as well as ubiquitin-containing aggregates indicative of the neuronal pathology. The mice receiving Q127 showed a marked increase in the reactive GFAP (+) astrocytes in striatum, septum and brain cortex, further indicating the neurodegenerative changes, accompanied by motor impairments. In experiment 2, plasmids Q20 or Q127 were complexed with ORMOSIL and were injected into the brain lateral ventricle or directly into the striatum of adult rats. In both routes of transfection, Q127 induced the appearance of reactive GFAP (+) astrocytes and activated ED1 antigen expressing microglia. An increase in the size of the lateral ventricle was also observed in rats receiving Q127. In transgenic mouse polyQ models, extensive pathologies occur outside the nervous system and the observed brain pathologies could reflect developmental effects of the toxic polyQ proteins. Our experiments show that the nervous tissue restricted expression of poly Q-extended peptides in adult brain is sufficient to evoke neuropathologies associated with HD and other polyQ disorders. Thus, nanotechnology can be employed to model pathological and behavioral aspects of genetic brain diseases in mice as well as in other species, providing a novel research tool for in vivo testing of single or multi-gene therapies.

Imaging Pancreatic Cancer Using Surface-Functionalized Quantum Dots

In this study, CdSe/CdS/ZnS quantum dots (QDs) were used as optical contrast agent for imaging pancreatic cancer cells in vitro using transferrin and anti-Claudin-4 as targeting ligands. CdSe/CdS/ZnS was chosen because the CdSe/CdS/ZnS QDs have better photoluminescence (PL) efficiency and stability than those of CdSe/ZnS. The transferrin-mediated targeting is demonstrated in both a cell-free coprecipitation assay as well as using in vitro confocal microscopy. Pancreatic cancer specific uptake is also demonstrated using the monoclonal antibody anti-Claudin-4. This targeted QD platform will be further modified for the purpose of developing as an early detection imaging tool for pancreatic cancer.

Quantum rod bioconjugates as targeted probes for confocal and two-photon fluorescence imaging of cancer cells

Live cell imaging using CdSe/CdS/ZnS quantum rods (QRs) as targeted optical probes is reported. The QRs, synthesized in organic media using a binary surfactant mixture, were dispersed in aqueous media using mercaptoundecanoic acid (MUA) and lysine. Transferrin (Tf) was linked to the QRs to produce QR-Tf bioconjugates that were used for targeted in vitro delivery to a human cancer cell line. Confocal and two-photon imaging were used to confirm receptor-mediated uptake of QR-Tf conjugates into the HeLa cells, which overexpress the transferrin receptor (TfR). Uptake was not observed with QRs that lacked Tf functionalization or with cells that were presaturated with free Tf and then treated with Tf-functionalized QRs.

Diacyllipid Micelle-Based Nanocarrier for Magnetically Guided Delivery of Drugs in Photodynamic Therapy

We report the design, synthesis using nanochemistry, and characterization of a novel multifunctional polymeric micelle-based nanocarrier system, which demonstrates combined function of magnetophoretically guided drug delivery together with light-activated photodynamic therapy. Specifically, the nanocarrier consists of polymeric micelles of diacylphospholipid-poly(ethylene glycol) (PE-PEG) coloaded with the photosensitizer drug 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), and magnetic Fe3O4 nanoparticles. The nanocarrier shows excellent stability and activity over several weeks. The physicochemical characterizations have been carried out by transmission electron micrography and optical spectroscopy. An efficient cellular uptake has been confirmed with confocal laser scanning microscopy. The loading efficiency of HPPH is practically unaffected upon coloading with the magnetic nanoparticles, and its phototoxicity is retained. The magnetic response of the nanocarriers was demonstrated by their magnetically directed delivery to tumor cells in vitro. The magnetophoretic control on the cellular uptake provides enhanced imaging and phototoxicity. These multifunctional nanocarriers demonstrate the exciting prospect offered by nanochemistry for targeting photodynamic therapy.

Transfection of tyrosine kinase deleted FGF receptor-1 into rat brain substantia nigra reduces the number of tyrosine hydroxylase expressing neurons and decreases concentration levels of striatal dopamine

The effects of HSV-1 amplicon and polyethyleneimine (PEI)-mediated transfection of dominant negative FGF receptor-1 mutant FGFR1(TK-) into the rat brain substantia nigra (SN) were examined in vivo to model the reduced FGF signaling documented to occur in Parkinson's disease. The number of SN neurons that expressed tyrosine hydroxylase (TH) was significantly reduced following HSV-1 FGFR1(TK-) intranigral delivery and similar changes were observed after PEI-mediated FGFR1(TK-) transfections. Further, we also observed a significantly lower striatal dopamine content following the PEI transfection of FGFR1(TK-). Thus, we conclude that reduced FGF signaling in the SN of Parkinsonian patients could play a role in the impaired dopaminergic transmission associated with the degenerative disease.

Organically modified silica nanoparticles: a nonviral vector for in vivo gene delivery and expression in the brain

This article reports on the application of organically modified silica (ORMOSIL) nanoparticles as a nonviral vector for efficient in vivo gene delivery. Highly monodispersed, stable aqueous suspension of nanoparticles, surface-functionalized with amino groups for binding of DNA, were prepared and characterized. Stereotaxic injections of nanoparticles, complexed with plasmid DNA encoding for EGFP, into the mouse ventral midbrain and into lateral ventricle, allowed us to fluorescently visualize the extensive transfection of neuronal-like cells in substantia nigra and areas surrounding the lateral ventricle. No ORMOSIL-based toxicity was observed 4 weeks after transfection. The efficiency of transfection equaled or exceeded that obtained in studies using a viral vector. An in vivo optical imaging technique (a fiber-based confocal fluorescent imaging system) provided an effective means to show the retention of viability of the transfected cells. The ORMOSIL-mediated transfections also were used to manipulate the biology of the neural stem/progenitor cells in vivo. Transfection of a plasmid expressing the nucleus-targeting fibroblast growth factor receptor type 1 resulted in significant inhibition of the in vivo incorporation of bromodeoxyuridine into the DNA of the cells in the subventricular zone and the adjacent rostral migratory stream. This in vivo approach shows that the nuclear receptor can control the proliferation of the stem/progenitor cells in this region of the brain. The results of this nanomedicine approach using ORMOSIL nanoparticles as a nonviral gene delivery platform have a promising future direction for effective therapeutic manipulation of the neural stem/progenitor cells as well as in vivo targeted brain therapy.

Assessment of viral and non-viral gene transfer into adult rat brains using HSV-1, calcium phosphate and PEI-based methods

CNS gene transfer could provide new approaches to the modelling of neurodegenerative diseases and devising potential therapies. One such disorder is Parkinson's disease (PD), in which dysfunction of several different metabolic processes has been implicated. Here we review the literature on gene transfer systems based on herpes simplex virus type 1 (HSV-1) and non-viral polyethyleneimine (PEI) and calcium phosphate nanoparticle methods. We also assess the usefulness of various CNS gene delivery methods and present some of our own data to exemplify such usefulness. Our data result from vectors stereotaxically introduced to the substantia nigra (SN) of adult rats and evaluated 1 week and/or 1 month post injection using histochemical methods to assess recombinant ss-galactosidase enzyme activity. Gene transfer using PEI or calcium phosphate-mediated transfections was observed for both methods and PEI was comparable to that of HSV-1 amplicon. Our data show that the amplicon delivery was markedly increased when packaged with a helper virus and was similar to the expression profile achieved with a full-size replication-defective HSV-1 recombinant (8117/43). We also examine whether PEI or HSV-1 amplicon-mediated gene transfer could facilitate assessment of the biological effects induced by a dominant negative FGF receptor-1 mutant to model the reduced FGF signalling thought to occur in Parkinson's disease.

Polycarboxylic acid nanoparticles for ophthalmic drug delivery: an ex vivo evaluation with human cornea

In ophthalmic drug delivery, a major problem is retaining an adequate concentration of a therapeutic agent in the pre-corneal area. Polycarboxylic acid carriers such as polyacrylic acid and polyitaconic acid in sub-colloidal, nanoparticulate hydrogel form have a strong potential for sustained release of a drug in ocular delivery. Formulations have been prepared of brimonidine loaded in polycarboxylic (polyacrylic and polyitaconic) acid nanoparticles for potential ophthalmic delivery. These particles were prepared by a reverse micro-emulsion polymerization technique with sizes in the range of 50 nm. The loading efficiencies of the drug brimonidine in the particles were shown to be between 80-85% for polyacrylic acid nanoparticles and between 65-70% for polyitaconic nanoparticles. The loading efficiency was also found to be pH dependent. In a preliminary biocompatibility test, human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability, whereas polyitaconic acid nanoparticles were found to be toxic. Two-photon laser scanning microscopic studies of the fluorescently labelled polyacrylic acid nanoparticles and human cornea shows that they are adhesive on the corneal surface. The polyacrylic acid nanoparticles demonstrated a controlled release of the opthalmological drug (Brimonidine) through the human cornea as compared to that of the commercial formulation, Alphagan.

Detection of trophic factor activated signaling molecules in cells by a compact fiber-optic sensor

This paper describes a highly sensitive method to detect trophic factor activated signaling molecules in cells using a compact fiber optic biosensor. The method is demonstrated by quantitative detection of phosphorylation of signal transducers and activators of transcription 3 (STAT3) in neuroblastoma cells. A single fiber-optic probe based on total internal reflection fluorescence sensing system is used. A 405 nm diode laser is used for evanescent wave excitation of immobilized labelled analyte on the probe surface. A compact charged coupled device (CCD) based spectrometer is used for recording the fluorescence signal. The method is two orders of magnitude more sensitive than the Western blotting technique.

Water soluble, core-modified porphyrins. 3. Synthesis, photophysical properties, and in vitro studies of photosensitization, uptake, and localization with carboxylic acid-substituted derivatives

Water soluble, core-modified porphyrins 1-5 bearing 1-4 carboxylic acid groups were prepared and evaluated in vitro as photosensitizers for photodynamic therapy. The 21,23-core-modified porphyrins 1-5 gave band I absorption maxima with lambda(max) of 695-701 nm. The number of carboxylic acid groups in the dithiaporphyrins 1-4 had little effect on either absorption maxima (lambda(max) of 696-701 nm for band I) or quantum yields of singlet oxygen generation [phi((1)O(2)) of 0.74-0.80]. Substituting two Se atoms for S gave a shorter band I absorption maximum (lambda(max) of 695 nm) and a smaller value for the quantum yield for generation of singlet oxygen [phi((1)O(2)) of 0.30]. The phototoxicity of 1-5 was evaluated against R3230AC cells. The phototoxicities of dithiaporphyrin 2, sulfonated thiaporphyrin 30, HPPH, and Photofrin were also evaluated against Colo-26 cells in culture using 4 J cm(-2) of 570-800 nm light. Compound 2 was significantly more phototoxic than sulfonated dithiaporphyrin 30, HPPH, or Photofrin. Cellular uptake was much greater for compounds 1, 2, and 5 relative to compounds 3 and 4. Confocal scanning laser microscopy and double labeling experiments with rhodamine 123 suggested that the mitochondria were an important target for dithiaporphyrins 1 and 2. Inhibition of mitochondrial cytochrome c oxidase activity in whole R3230AC cells was observed in the dark with compounds 1 and 30 and both in the dark and in the light with core-modified porphyrin 2.

Ceramic-based nanoparticles entrapping water-insoluble photosensitizing anticancer drugs: a novel drug-carrier system for photodynamic therapy

A novel nanoparticle-based drug carrier for photodynamic therapy is reported which can provide stable aqueous dispersion of hydrophobic photosensitizers, yet preserve the key step of photogeneration of singlet oxygen, necessary for photodynamic action. A multidisciplinary approach is utilized which involves (i) nanochemistry in micellar cavity to produce these carriers, (ii) spectroscopy to confirm singlet oxygen production, and (iii) in vitro studies using tumor cells to investigate drug-carrier uptake and destruction of cancer cells by photodynamic action. Ultrafine organically modified silica-based nanoparticles (diameter approximately 30 nm), entrapping water-insoluble photosensitizing anticancer drug 2-devinyl-2-(1-hexyloxyethyl) pyropheophorbide, have been synthesized in the nonpolar core of micelles by hydrolysis of triethoxyvinylsilane. The resulting drug-doped nanoparticles are spherical, highly monodispersed, and stable in aqueous system. The entrapped drug is more fluorescent in aqueous medium than the free drug, permitting use of fluorescence bioimaging studies. Irradiation of the photosensitizing drug entrapped in nanoparticles with light of suitable wavelength results in efficient generation of singlet oxygen, which is made possible by the inherent porosity of the nanoparticles. In vitro studies have demonstrated the active uptake of drug-doped nanoparticles into the cytosol of tumor cells. Significant damage to such impregnated tumor cells was observed upon irradiation with light of wavelength 650 nm. Thus, the potential of using ceramic-based nanoparticles as drug carriers for photodynamic therapy has been demonstrated.

Brimonidine formulation in polyacrylic acid nanoparticles for ophthalmic delivery

In ocular drug delivery, a major problem is providing an adequate concentration of a therapeutic agent in the precorneal area. Mucoadhesive carriers such as polyacrylic acid in sub-colloidal, nanoparticulate form, have a strong potential for ophthalmic drug delivery. A formulation of brimonidine loaded in polyacrylic acid nanoparticles has been prepared for potential delivery in ophthalmic therapy. The particles were prepared by a reverse microemulsion polymerization technique and their sizes were in the range of 50 nm. In a preliminary biocompatibility test, Caco-2 cells (human primary colonic tumour adenocarcinoma) and human corneal epithelial cells incubated with polyacrylic acid nanoparticles were found to retain their viability over varying times. The loading efficiency of the drug brimonidine in the particles was shown to be between 80-85% and pH dependent. The bioadhesive polyacrylic hydrogel nanoparticles, used in the present study, exhibited superior loading properties for brimonidine, and the formulation was stable for more than 5 weeks. When the drug-loaded nanoparticles were dispersed in a phosphate buffer saline (pH = 7.4), the drug was slowly released over several hours. Two-photon laser scanning microscopic studies of dye-conjugated polyacrylic acid nanoparticles demonstrated the accumulation of the particles on the surface and intercellular spaces of Caco-2 cells.

A monomethine cyanine dye Cyan 40 for two-photon-excited fluorescence detection of nucleic acids and their visualization in live cells

Monomethine cyanine dye 4-((1-methylbenzothiazolyliliden-2)methyl)-1,2,6-trimethylpyridinium perchlorate (Cyan 40) was investigated as a two-photon-excited fluorescence probe for nucleic acids (NA). Cyan 40 has been shown to demonstrate efficient two-photon-excited fluorescence in the presence of NA in vitro in contrast to solutions without NA. Two-photon confocal laser scanning microscopy (TPCLSM) and two-photon laser scanning microspectrofluorometry were used to check the possibility of using Cyan 40 as two-photon-excited fluorescence label for NA in living cells. Study of dye effect on viability of cells was also carried out. We ascertained that Cyan 40 is a cell-permeant dye, manifesting efficient two-photon-excited fluorescence when bound to NA in living cells, without any significant influence on viability of cells. TPCLSM images obtained from stained cells indicate preferential RNA staining by Cyan 40 compared with DNA.

Studies on the mechanism of action of a targeted chemotherapeutic drug in living cancer cells by two photon laser scanning microspectrofluorometry

In this study, we present a spectroscopic study of the entry pattern of a chemotherapeutic drug (AN-152) and its carrier hormone ([D-Lys(6)]LH-RH) into living cancer cells, with the help of our two-photon probes and a home-built localized microspectrofluorometer coupled with two photon laser scanning microscope (TPLSM). Due to the inherent localization ability of TPLSM, we were able to identify the drug and carrier location in different compartments of the cancer cells in vitro. The apparent doxorubicin-assisted nucleic accumulation of AN-152 suggests a possible nuclear action of the drug on cell proliferation.

Regulation of targeted chemotherapy with cytotoxic lutenizing hormone-releasing hormone analogue by epidermal growth factor

Targeting chemotherapy selectively to cancers can reduce the toxic side effects. AN-152, a conjugate of doxorubicin and [D-Lys6]-luteinizing hormone-releasing hormone (LH-RH), is more potent against LH-RH receptor-bearing cancers and produces less peripheral toxicity than doxorubicin. Many cancers, e.g., 50% of breast cancers, but few normal tissues express these receptors, providing a selective target for this cytotoxic conjugate. In this study, the effectiveness of AN-152 was heightened by receptor up-regulation. The cytotoxic effect of AN-152 can be regulated by the number of active LH-RH receptors on cancer cells. LH-RH receptor-positive (MCF-7) and -negative (UCI-107) cancer cells were treated with epidermal growth factor (EGF) or the somatostatin analogue, RC-160. EGF and RC-160 have been shown previously to regulate LH-RH receptors through phosphorylation. The effect of receptor regulation, by hormone exposure, on the cytotoxicity of AN-152 and doxorubicin and on the cellular uptake of AN-152, [D-Lys6]LH-RH, or doxorubicin was assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and by two-photon laser scanning microscopy. The results demonstrated that the cellular entry of the conjugate was: (a) specific for cancers with LH-RH receptors; (b) up-regulated by EGF; (c) down-regulated by RC-160; and (d) the cytotoxicity of the AN-152 paralleled the efficiency of entry. This study illustrates the potential use of receptor regulation for increasing the efficacy of chemotherapeutic approaches that are directed to cell surface receptors.

Association of human herpesvirus 6 with the demyelinative lesions of progressive multifocal leukoencephalopathy

Progressive Multifocal Leukoencephalopathy (PML) is a primary demyelinating disease of the central nervous system occurring almost exclusively in individuals with impaired cell-mediated immunity. The JC polyoma virus has been accepted as the etiologic agent ofPML. Using a two-step in-situ polymerase chain reaction procedure to amplify and detect genomic DNA of human herpesvirus-6 (HHV6) in formalin-fixed paraffin-embedded archival brain tissues, a high frequency of infected cells was consistently detected in PML white matter both within and surrounding demyelinative lesions and HHV6 genome was found mainly within oligodendrocytes. Lesser amounts of HHV6 genome were detected in most normal, AIDS, and other neurological disease control tissues. Immunocytochemistry for HHV6 antigens showed actively infected nuclei of swollen oligodendrocytic morphology only within the demyelinative lesions of PML but not in adjacent uninvolved tissue. In addition, no HHV6 antigens were detectable in control tissues including brains of individuals with HIV-1 encephalopathy but without PML. Double immunohistochemical staining for JC virus large T antigen and HHV6 antigens demonstrated co-labeling of many swollen intralesional oligodendrocytes in the PML cases. The evidence suggests that HHV6 activation in conjunction with JC virus infection is associated with the demyelinative lesions of PML.

Identification of salivary proteins inhibiting herpes simplex virus 1 replication

Salivary proteins play an important role in the maintenance of the oral ecology. Previous studies have indicated that human submandibular-sublingual and parotid salivas can selectively suppress the in vitro infectivity of herpes simplex virus 1. The purpose of this study was to identify the salivary components in human submandibular-sublingual saliva that modulate in vitro infectivity. Assessment of the interaction of viral particles with salivary components was accomplished using an in vitro solid-phase assay. These experiments revealed that herpes simplex virus particles selectively interact with the members of the salivary proline-rich protein and cystatin families. Subsequent yield reduction assays demonstrated the ability of proline-rich proteins and salivary cystatins to inhibit the viral replication, with basic proline-rich peptides being more effective. Subsequent assays suggest that basic proline-rich peptides reduced the virus titer by interfering with penetration and/or cellular processing of virus within the target cell. Collectively, these results further suggest that salivary proteins have an important role in the host defense mechanism against recurrent herpesvirus infection.

Interaction of HIV-1 and human salivary mucins

Previous studies have suggested that salivary secretions may act as inhibitors of HIV-1 replication in vitro. This inhibitory activity was determined to be associated mainly with secretions obtained from the human submandibular-sublingual glands, and subsequent electron micrographs revealed the association of viral particles with the salivary sediment. Fractionation of human submandibular-sublingual (HSMSL) saliva by size-exclusion chromatography was initiated, and resulting fractions were tested for their ability to modulate the replication of HIV-1 using a plaque assay on HeLa CD4+ cell monolayers. Results indicated that the filtration-sensitive inhibitory activity was primarily associated with the mucin-rich fractions, and the inhibitory activity was found to reduce the number of infectious units by 75%. To determine the identity of the salivary components involved, adsorption experiments involving the interaction of HIV particles with immobilized salivary components were performed. Immunological counter staining revealed an interaction of HIV particles as well as recombinant gp120 with the lower-molecular-weight mucin. Electron microscopic examination of the mucin-rich fractions-HIV incubates revealed the aggregation of virus particles by salivary components. These results suggest that human salivary mucins may have a role in modulating the infectivity of HIV-1.

Modulation of herpes simplex virus type 1 replication by human salivary secretions

Saliva functions to protect the oral cavity from pathogenic invasion by modulating the ability of microbes to colonize the oral surfaces or limiting their growth and/or viability. Although the role of salivary secretions in the modulation of the oral bacteria flora has received considerable attention, little is known concerning its role in viral pathogenesis. Accordingly, the purpose of this study was to assess the effect of salivary secretions on herpes simplex virus type 1 (HSV-1) replication. Initially, HSV-1 plaque and titer reduction assays were performed to determine the ability of human submandibular/sublingual (HSMSL) and parotid (HPS) salivas to inhibit the early stages of HSV-1 infection (adsorption and penetration). Our results suggested that both HSMSL and HPS possess cell-protective and virus neutralization activities, with HSMSL being more active than HPS. Additional experiments were performed to determine the effect of saliva on the yield of virus progeny. Again, HSMSL caused a greater reduction of HSV-1 replication than did HPS. A similar effect could not be obtained using vaccinia, suggesting that this inhibitory activity of human saliva is selective. Collectively, these results suggest that human salivary secretions can modulate the replication of HSV-1 in vitro.

Aggregation of human immunodeficiency virus type 1 by human salivary secretions

Human immunodeficiency virus (HIV-1) is generally transmitted by parenteral contact with infected body secretions. Although extensive epidemiological data and familial studies have failed to provide any conclusive data that saliva may act as a vehicle for transmission of AIDS, both professional and public anxieties remain. The present study, as well as others, suggests that salivary secretions may act as inhibitors of HIV-1 replication in vitro. In our study, the inhibitory activity was determined to be associated mainly with secretions obtained from the human submandibular-sublingual glands. Human submandibular-sublingual (HSMSL) and parotid (HPS) salivas were collected and tested for their ability to modulate the replication of HIV-1, using a plaque assay on HeLa/CD4+ cell monolayers. Initial results examining freshly collected salivary samples from ten individuals confirmed the results previously obtained by Fox et al. (1988, 1989). An average plaque reduction of approximately 66% was obtained with HSMSL, in contrast to 34% reduction obtained with HPS. Titration of the inhibitory activity in HSMSL showed detectable levels at a 1:500 dilution. Comparison of inhibitory activity of dialyzed and lyophilized saliva to fresh saliva indicated little difference between the two samples when filtration occurred after the addition of HIV-1. However, the effect of filtration was significantly diminished in the lyophilized samples. Electron microscopic examination of the saliva-HIV incubates revealed the aggregation/entrapment of virus particles by salivary components. These results suggest that human salivary secretions (with HSMSL > HPS) may have a role in modulating the infectivity of HIV-1.

Formation of salivary-mucosal pellicle: the role of transglutaminase

The present investigation was carried out to identify salivary components of mucosal pellicles in vivo and explore further the mechanism of interaction between salivary molecules and buccal epithelial cells. By using specific antisera and immunoprotein blotting, high-(MG1) and low-(MG2) molecular-mass salivary mucins, amylase, salivary cystatins and proline-rich proteins were detected within mucosal pellicle in vivo. In addition, the data indicated that the mucins and proline-rich proteins could be cleaved into lower-molecular-mass products, whereas the proline-rich proteins could also be cross-linked into higher-molecular-mass complexes. The role of buccal epithelial cell transglutaminase in these interactions was further studied by utilizing purified iodinated amylase, neutral cystatin SN and acidic proline-rich proteins 1 and 3 (APRP1 and 3). After incubation with buccal epithelial cells in vitro 125I-labelled APRPs appeared to undergo a greater degree of cross-linking than 125I-labelled cystatin SN, as determined by SDS/PAGE/autoradiography. Amylase did not appear to be cross-linked at all. Recovery of 125I-labelled APRPs and 125I-labelled cystatin SN with epithelial cell envelopes after repeated extraction suggested that both molecules were cross-linked to envelope proteins, but that 125I-labelled APRPs were cross-linked to a greater degree than 125I-labelled cystatin SN. Cross-linking in buccal epithelial cell preparations was inhibited by an excess of methylamine hydrochloride, a transglutaminase substrate. In a further assessment of amylase, cystatin and APRPs as transglutaminase substrates, only APRP3 and a partially purified preparation of APRPs acted as an amine acceptor for the cross-linking of [14C]methylamine by purified transglutaminase, as determined by SDS/PAGE/fluorography. This reaction was completely inhibited by excess EDTA. The combined data from this study suggest that during mucosal pellicle formation multiple components of saliva adsorb to buccal epithelial cell surfaces, and that, within this group, selected components are enzymically cross-linked by an epithelial transglutaminase and/or proteolytically cleaved into smaller fragments.

Large-scale purification and characterization of the major phosphoproteins and mucins of human submandibular-sublingual saliva

The major components of human submandibular-sublingual saliva (HSMSL) are mucins, amylases, cystatins, proline-rich proteins and statherin. Structure-function studies of these molecules have been hampered by the small amounts of purified materials that can be isolated from human secretions. The present study describes an integrated purification protocol for the large-scale preparation of many of these molecules. To dissociate partially heterotypic complexes among salivary molecules, HSMSL was initially fractionated into four pools by gel filtration with 6 M-guanidine hydrochloride. Subsequent fractionation of these four pools by gel-filtration and ion-exchange chromatography resulted in the purification of high- and low-Mr mucins, neutral and acidic cystatins, acidic and basic proline-rich proteins and statherin. Many variants or isoforms of these salivary molecules have been identified and biochemically characterized. Biochemical studies indicated that the low-Mr mucin exists as two isoforms which vary in their sialic acid to fucose ratios. Three isoforms of acidic cystatin S were characterized which differ in their phosphate content. Two isoforms of a basic proline-rich peptide were identified; the smaller peptide was a truncated form missing the first seven amino acids.

The effects of human salivary cystatins and statherin on hydroxyapatite crystallization

The adsorption, at hydroxyapatite surfaces of neutral cystatin SN, acidic cystatin S and the phosphoserine-containing acidic cystatin S1 was compared to that of statherin. The effects of these adsorbed proteins on the constant-composition growth kinetics of hydroxyapatite were also studied. The neutral cystatin SN had a higher adsorption maximum than the acidic cystatins S and S1. Although the affinity of cystatin for hydroxyapatite surfaces was lower than that of statherin, their influence on the growth kinetics of hydroxyapatite was considerably greater, with the acidic cystatin S1 being the most active. At a surface concentration of 7.0 x 10(-8) mol m-2 hydroxyapatite, the cystatins decreased the rate of crystal growth by 80-95% as compared to that in the absence of protein. At this concentration, statherin showed a growth inhibition of 40%.

Characterization of salivary alpha-amylase binding to Streptococcus sanguis

The purpose of this study was to identify the major salivary components which interact with oral bacteria and to determine the mechanism(s) responsible for their binding to the bacterial surface. Strains of Streptococcus sanguis, Streptococcus mitis, Streptococcus mutans, and Actinomyces viscosus were incubated for 2 h in freshly collected human submandibular-sublingual saliva (HSMSL) or parotid saliva (HPS), and bound salivary components were eluted with 2% sodium dodecyl sulfate. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western transfer, alpha-amylase (EC 3.2.1.1) was the prominent salivary component eluted from S. sanguis. Studies with 125I-labeled HSMSL or 125I-labeled HPS also demonstrated a component with an electrophoretic mobility identical to that of alpha-amylase which bound to S. sanguis. Purified alpha-amylase from human parotid saliva was radiolabeled and found to bind to strains of S. sanguis genotypes 1 and 3 and S. mitis genotype 2, but not to strains of other species of oral bacteria. Binding of [125I]alpha-amylase to streptococci was saturable, calcium independent, and inhibitable by excess unlabeled alpha-amylases from a variety of sources, but not by secretory immunoglobulin A and the proline-rich glycoprotein from HPS. Reduced and alkylated alpha-amylase lost enzymatic and bacterial binding activities. Binding was inhibited by incubation with maltotriose, maltooligosaccharides, limit dextrins, and starch.