Sequential or multiplex electrochemical detection of miRs based on the p19 function relative to three sandwiches of different structural hybrids on the liposomal sensor.

In this work, we designed a liposomal electrochemical sensor with DOTAP-DOPE liposome, chimeric probes, p19 as a caliper molecule, and the competitor structural hybrid (just RNA) for detection of three micro-RNAs in one SPCE/GNP electrode. The sensor is stabled when the cationic spherical DOTAP-DOPE liposomes sandwich with hybrids of the different sandwiched of probes (T-M-linear, Stem) and 21-124a-221miRs. With the addition of P19, in the presence of a sandwiched competitor (T-linear/21miR), the system is stable (ON) and is shut off in the presence of structural sandwiched hydrides of M-linear+124a/Stem+221 miR due to the lack of adequate access to segments of RNA-miRs of chimeric probes. For the first time in this study, three probes were sandwiched on the separate liposome for sequential identification of 21-124a-221 or multiplex detection of miRs (221 or 124a with 21) with high specificity and sensitivity (as low as 0.1 fM). Electrochemical impedance (EIS) were performed for sensing three miRs in PBS containing 1 mM [Fe(CN)6]-3/-4 which DOTAP-DOPE liposome acted as an enhancing intermediate layer in the electrochemical reactions. Transmission Electron Microscopy (TEM)), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Ultraviolet-Visible (UV) spectroscopic techniques are used to understand the interactions between the DOPE-DOTAP, AuNP, different probes, miRs and p19.

Author Correction: Electrochemical Sensor for Detection of miRs Based on the Differential Effect of Competitive Structures in The p19 Function.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Electrochemical Sensor for Detection of miRs Based on the Differential Effect of Competitive Structures in The p19 Function.

The present study aim to design a liposomal electrochemical sensor using 1, 2-dioleoyl-3-trimethylammoniumpropane (DOTAP) and dioleoylphosphatidylethanolamine(DOPE), chimeric probes and p19, it has been considered as a caliper molecule as well. Also the competitor structural hybrid (RNA) was used to detect three types of miRs in one screen printed electrode modified by gold nanoparticle (SCPE/GNP). In this purpose, the sensor signal stabilized when the cationic DOTAP-DOPE with hybrids of the chimeric probes (Stem, M-linear) sandwiched in order to detect 221-124a miRs. Given the lack of accessibility to RNA-miRs segments of chimeric probes, p19 inhibited the electrochemical reaction and shifted signal to off. After that p19 connected with the free hybrid of T-linear/21miR (just RNA) as competing for structure and the signal was shifted to ON, again. In this study, the electrochemical measurements were performed between the potentials at -0.4 V and +0.4 V with 1 mM [Fe(CN)6]-3-/4 which DOTAP-DOPE acted as an enhancer layer in the electrostatically reaction. This sensor determines as low as 0.4 fM of miRNA with high selectivity and specificity for sequential analysis of 124a-221-21 miRs in just 2 h.

Stable and sustained release liposomal formulations of celecoxib: In vitro and in vivo anti-tumor evaluation.

Celecoxib (CLX) is a selective COX-2 inhibitor with anticancer potential in a COX-2 dependent and independent manner. CLX's low water solubility has a dose limiting effect on its utilization in cancer treatment. Here, we developed liposomal drug delivery systems to allow a systemic administration and increase tumor accumulation of CLX based on the enhanced permeability and retention (EPR) mechanism. Nine liposomal formulations has been prepared with different phospholipid compositions; among them three sets of liposomal formulations were selected based on characterization and stability for further studies. Anti-tumor effects of CLX-entrapped liposomal formulations were tested in vitro by cytotoxicity test and in vivo in BALB/c mice bearing C26 colon carcinoma. Biodistribution of liposomal-CLX has been studied by radiolabeling of CLX with I125.The selected formulations had average size of about 100 nm, a narrow monomodal distribution with storage stability of at least one year at 4 °C. The HSPC/DSPG/cholesterol/DSPE-PEG2000/CLX (65/10/10/5/10 M ratio) liposomal formulation had slowest release profile and greatest antitumor effects in vivo. This liposomal I125CLX formulation had a three times more accumulation in tumor site in comparison to the free I125CLX. Liposomal CLX may serve as a safe, slow release and effective anti-tumor agent and merits further investigation.

PEGylation of cationic liposomes encapsulating soluble Leishmania antigens reduces the adjuvant efficacy of liposomes in murine model.

Although there have been several attempts to develop a vaccine against leishmaniasis, no vaccine in human has been developed yet. Liposomes consisting of 1, 2-dioleoyl-3-trimethylammonium-propane (DOTAP) encapsulating soluble Leishmania antigens (SLA) enhance protective immunity of SLA against Leishmania major infection in mice. However, they immobilized at the injection site because of their positive charge. To overcome the problem, shielding the surface charge with polyethylene glycol (PEGylation) was chosen in this study. Liposomal SLA consisting different concentrations of PEG (1.9%-15% mol) were prepared. BALB/c mice were immunized three times in 3 weeks intervals with different formulations. Lesion development and parasite burden in footpad and spleen were evaluated to specify the type of generated immune response and extent of protection. Th1/Th2 cytokine profiles and IgG isotypes were also analysed. The maximum protection was observed in mice immunized with Lip-SLA or pLip-SLA (1.9%) due to smaller footpad swelling, reduction in parasite load, an increase in IgG2a and IFN-γ production. Our results showed that immunization of mice with a high level of PEG (>7.5%) did not improve protective immunity of liposomal SLA. The presence of PEG, particularly more than 3.75%, is not recommended for protection against leishmaniasis.

Circulating microRNA: a new candidate for diagnostic biomarker in neuroblastoma.

Neuroblastoma (NB) is known as a pediatric neoplasm that is associated with variable histopathological features. The use of biomarkers contributes to the monitoring and treatment of various malignancies such as NB. The identification of novel biomarkers such as (epi)genetic biomarkers and microRNAs (miRNAs) in NB has led to better treatments of NB. Among them, miRNAs have emerged as powerful tools in diagnosis, prognosis and therapeutic biomarkers for patients with NB. Circulating biomarkers such as circulating miRNAs present in body fluids (for example, plasma, serum and urine) provided an interesting field of study in NB treatment. The miRNAs have central roles in different pathogenic events in various malignancies such as NB. Hence, these molecules can be a suitable candidate for monitoring and treating NB patients. Here, we summarize some miRNAs as potential prognosis, diagnosis and therapeutic biomarkers in NB.

Mesenchymal stem cell: a new horizon in cancer gene therapy.

Cancer is one of the main problems in public health worldwide. Despite rapid advances in the diagnosis and treatment of cancer, the efficacy of current treatment strategies is still limited. There are promising new results in animal models whereby mesenchymal stem cells (MSCs) can be used as vehicles for targeted therapies. The use of MSCs as therapeutic biological vehicles in cell therapy has several advantages, including immune-silence, tumor tropism, easy and rapid isolation, ex vivo expansion, multilineage differentiation and the capacity to deliver a number of therapeutic agents. Some studies have shown that the microenvironment of the tumor provides a preferential niche for homing and survival of MSCs. Here, we have highlighted various applications of MSCs in cancer gene therapy.

The Comparison of Biodistribution, Efficacy and Toxicity of Two PEGylated Liposomal Doxorubicin Formulations in Mice Bearing C-26 Colon Carcinoma: a Preclinical Study.

BACKGROUND: Over the past several years, the considerable attention has been progressively given to liposomal formulations of anthracyclines. SinaDoxosome(®) (Exir Nano Sina Company, Iran) is a pegylated liposomal doxorubicin (DOX) which approved by Food and Drug Administration of IRAN for treatment of some types of cancer. The aim of this study was to compare the biodistribution, efficacy, cardiotoxicity and hepatotoxicity of SinaDoxosome(®) with Caelyx(®) in mice bearing C-26 colon carcinoma. METHODS AND RESULTS: Mice tumor size evaluation during the experimental period (28 days) showed comparable therapeutic efficacy of nano-formulations. The biodistribution studies showed no significant difference in DOX tissue concentration between Caelyx(®) and SinaDoxosome(®). DOX induced-ECG changes were not detected in nano-formulations. No significant alteration was found in biochemical indexes of myocardial injury in mice exposed to nano-formulations in comparison with control mice. The tissue oxidative parameters such as lipid peroxidation, glutathione, catalase and superoxide dismutase was significantly changed as the results of free DOX treatment. However, the oxidative status of Caelyx(®) and SinaDoxosome(®) treated animals did not showed any changes. The experiment also revealed that apoptotic pathway was not activated in the heart of mice exposed to nano-formulations. CONCLUSIONS: Although this investigation showed that Caelyx(®) and SinaDoxosome(®) are similar in terms of biodistribution, efficacy and toxicity, appropriate clinical evaluations in patients should be considered.

PiggyBac as a novel vector in cancer gene therapy: current perspective.

Selection of suitable delivery system is one of the crucial aspects in gene therapy that determines the efficiency of gene therapy. The past two decades have witnessed extensive efforts for finding safe and efficient vectors to overcome the limitations of viral vectors. The utilization of DNA transposon-based vectors for gene therapy has emerged as a promising non-viral alternative. DNA 'cut-and-paste' is one of the main mechanisms of genome engineering by transposon elements. However, the lack of an efficient transposition system has limited the utilization of transposon vectors in mice and mammalian systems. PiggyBac (PB) is known as a highly efficient DNA transposon originally isolated from Trichoplusia ni as an alternative to Sleeping Beauty (SB). It has been shown that PB can be functional in various species including mammalian systems. This vector could overcome some limitations of other vectors in cancer gene therapy. Some advantages of PB include the capacity for integration into the genome and providing a stable expression, capacity to harbor 10 and 9.1 kb of foreign DNA into the host genome, without a significant reduction in their transposition activity and display non-overlapping targeting preferences. However, to advance PB to clinical applications, some obstacles still require to be overcome to improve its safety and efficiency. Hence, it seems that this vector could open new horizons in gene and cancer therapy.

Effects of combined therapy with silymarin and glucantime on leishmaniasis induced by Leishmania major in BALB/c mice.

Leishmania major is resistant to the traditional treatments in many parts of the world. PgpA, a member of (ABC) transporter superfamily, has been identified in Leishmania involved in antimony resistance. Silymarin can inhibit PgpA. The aim of this study was to determine the effect of combined therapy with glucantime and silymarin on Cutaneous Leishmaniasis. The effects of silymarin on response of L. major to glucantime were evaluated with amastigote macrophage and mice model of leishmaniasis. Immediately after injection in mice inoculated into footpads with L. major amastigote, systemic treatment was performed and the size of footpad swelling was measured twice a week. 4 and 8 weeks after the beginning of the treatment, splenic parasite burden was done. Silymarin showed no significant effect on the response of L. major promastigotes to glucantime. 2 formulations (glucantime 25 µm with silymarin 25 µm or 12.5 µm) reduced cell death in amastigote assays. The effect of silymarin on footpad swelling was detected when the combination of low-dose glucantime (20 mg/kg) with 25-50 mg/kg silymarin (especially 50 mg/kg) were used at day 22 of post infection (P<0.05). According to the parasite burden data, use of silymarin in the presence of different doses of glucantime, did not show significant effect compared to glucantime alone. The results of this study suggest that silymarin in conjunction with glucantime may have benefit effects in murine model of cutaneous leishmaniasis.

Use of topical liposomes containing meglumine antimoniate (Glucantime) for the treatment of L. major lesion in BALB/c mice.

Treatment of cutaneous leishmaniasis (CL) is a dream for the patients, health care authorities and scientists. The aim of this study was to develop a topical liposomal meglumine antimoniate (MA, Glucantime™) (Lip-MA) formulation and evaluate the therapeutic effects of the preparation on lesion induced by Leishmania major in BALB/c mice. Liposomes containing 22.5% MA (6.4% Sb(+5)) with and without oleic acid (LMA-OA and LMA) were formulated using fusion method plus homogenization and characterized for the size and encapsulation efficiency. The penetration of MA from the LMA-OA and LMA formulations through and into the skin was checked in vitro using Franz diffusion cells fitted with mouse skin at 37°C for 8h. The in vitro permeation data showed that almost 1.5% of formulations applied in the mouse skin were penetrated and the amount retained in the skin was about 65%. The 50% effective dose of LMA and LMA-OA against amastigotes of L. major was 46.36 and 41.01 µg/ml, respectively. LMA or LMA-OA was used topically twice a day for 4 weeks to treat the lesion induced by L. major in susceptible BALB/c mice. The results showed a significantly (P<0.001) smaller lesion size in the treated groups of mice compared to the control groups which received either empty liposomes or phosphate-buffered saline (PBS). The spleen parasite burden was significantly (P<0.001) lower in the treated groups compared to the control groups receiving either empty liposomes or PBS at the end of the treatment period. However, when the treatment was stopped, the lesion size progressed and spleen parasite burden increased in LMA and LMA-OA groups, but still was significantly less than the control groups (P<0.05). There was no significant difference between the two formulations of LMA and LMA-OA. The results suggested that topical liposomes containing MA might be an appropriate choice for clinical trials for the treatment of CL.

Immunization against leishmaniasis by PLGA nanospheres loaded with an experimental autoclaved Leishmania major (ALM) and Quillaja saponins.

Immune responses against the Leishmania antigens are not sufficient to protect against a leishmania challenge. Therefore these antigens need to be potentiated by various adjuvants and delivery systems. In this study, Poly (d,l-lactide-co-glycolide (PLGA) nanospheres as antigen delivery system and Quillaja saponins (QS) as immunoadjuvant have been used to enhance the immune response against autoclaved Leishmania major (ALM). PLGA nanospheres were prepared by a double-emulsion (W/O/W) technique. Particulate characteristics were studied by scanning electron microscopy and particle size analysis. Mean diameter for nanospheres loaded with ALM+QS was 294 ± 106 nm. BALB/c mice were immunized three times in 3-weeks intervals using ALM plus QS loaded nanospheres [(ALM+QS)PLGA], ALM encapsulated with PLGA nanospheres [(ALM)PLGA], (ALM)PLGA + QS, ALM + QS, ALM alone or PBS. The intensity of infection induced by L. major challenge was assessed by measuring size of footpad swelling. The strongest protection, showed by significantly (P < 0.05) smaller footpad, were observed in mice immunized with (ALM)PLGA. The (ALM+QS)PLGA group showed the least protection and highest swelling, while the (ALM)PLGA+QS, ALM+QS and ALM showed an intermediate protection with no significant difference. The mice immunized with ALM and ALM+QS showed the highest IgG2a/IgG1 ratio (P < 0.01), followed by (ALM)PLGA+QS. The highest IFN-γ and lowest IL-4 production was seen in (ALM)PLGA+QS, ALM+QS groups. The highest parasite burden was observed in (ALM)PLGA+QS and (ALM+QS)PLGA groups. It is concluded that PLGA nanospheres as a vaccine delivery system could increase the protective immune responses, but QS adjuvant has a reverse effect on protective immune responses and the least protective responses were seen in the presence of this adjuvant.

Preparation and characterization of poly lactide-co-glycolide nanoparticles of SN-38.

SN-38 (7-ethyl-10-hydroxycamptothecin) is the active metabolite of irinotecan (CPT-11), which is 100-1000-fold more cytotoxic than irinotecan. Nonetheless, the extreme hydrophobicity of SN-38 has prevented its clinical use. SN-38 is poorly soluble in aqueous solutions, and it is practically insoluble in most physiologically compatible and pharmaceutically acceptable solvents. One way of improving the solubility and stability of SN-38 is to formulate the drug into nanoparticles. Incorporation of cytotoxic agents into nanoparticles has also shown increased toxicity. In this study, poly lactide-co-glycolide was used for the preparation of nanoparticles of SN-38. The nanoparticles were fabricated by an emulsification/solvent evaporation method. The effect of several variables on nanoparticle characteristics was evaluated, including the ratio of drug-polymer, the amount of the poly vinyl alcohol as surfactant, and the internal phase volume/composition. The SN-38 encapsulation efficiency and the particle size distribution were optimized by varying these parameters. Nanoparticles were spherical with a relatively mono-dispersed size distribution. As the ratio of acetone to dichloromethane increased, a considerable decrease in the particle size of nanoparticles was achieved. The encapsulation efficiency of all samples was more than 80%. Changing the poly vinyl alcohol concentration in the external phase had some effects on size and morphology and encapsulation efficiency. It was shown that SN-38 nanoparticles are considerably stable in a long-term stability study.

Nasal immunization studies by cationic, fusogenic and cationic-fusogenic liposomes encapsulated with tetanus toxoid.

Particulate antigens are more effective than soluble antigens in induction of systemic and mucosal immunity; possibly because they are more efficiently endocytosed by mucosal-associated lymphoid tissue (MALT) M cells. In this study, we determined the systemic and mucosal immune responses in rabbits following intranasal immunization with tetanus toxoid (TT) entrapped in cationic, fusogenic and cationic-fusogenic liposomes. Liposomes containing TT were prepared by dehydration-rehydration method. The volume mean diameter of cationic, fusogenic and cationic-fusogenic liposomes were 3.4 +/- 0.6, 4.3 +/- 2.3 and 3.4 +/- 1.5 microm, respectively. Encapsulation efficiency of TT in cationic, fusogenic and cationic-fusogenic liposomes was respectively determined as 49.1 +/- 8.4%, 48.5 +/- 2.1% and 50.8 +/- 4.9%. After 3 months, the leaking of encapsulated TT from liposomes ranged between 2.02 - 5.46%. Immunoreactivities of encapsulated TT in all kinds of liposomes were completely preserved, as studied by Sodium Dodecyl Sulfate - Polyacrylamide Gel Electrophoresis (SDS-PAGE) and Enzyme-Linked Immunosorbent Assay (ELISA). The highest serum immunoglobulin G (IgG) and antitoxin titers were observed in groups immunized with solution formulation (P< 0.001). However, the highest mucosal secretory IgA (sIgA) titers were achieved by fusogenic liposomes (five times more titers compared with TT solution, and 15 times more titers compared with i.m. vaccine), followed by cationic-fusogenic liposomes. No hemolysis was occurred on incubation of liposomes and human erythrocytes. Also after nasal administration of plain liposomes to human volunteers, no local irritation was seen. This study suggests that intranasal administration of fusogenic and cationic-fusogenic liposomes encapsulated with vaccines could be an effective way for inducing mucosal immune responses.

Formulation, characterization and release studies of alginate microspheres encapsulated with tetanus toxoid.

Alginate is a safe, non-immunogenic and inexpensive natural polymer with high mucoadhesive properties. Alginate microspheres can be used as a delivery system for antigens to mucosal surfaces. In the present study alginate microspheres were prepared by an emulsification technique. The effects of sonication time, concentration of alginate, emulsifier and calcium chloride, and also the volume of calcium solution, were evaluated on mean size, size range, surface roughness and porosity, sphericity and clumping of microspheres using an optical microscope and particle size analyzer. The most desirable conditions were 90 s sonication, 3% alginate solution, 2% surfactant and 60 ml of 0.33% CaCl2 in octanol. The resulting microspheres had a mean size of 1.34 +/- 0.3 microm and size range of 0.3 +/- 2.0 microm, with no surface roughness and porosity, low clumping and high sphericity. The encapsulation efficiency was about 47.7%. All batches showed nearly the same release profiles with a low burst release. The stability of the model antigen (tetanus toxoid (TT)) extracted from microspheres was confirmed by SDS-PAGE; and the antigenicity of TT was studied by ELISA and found to be 91 +/- 5% of the original TT. It can be concluded that, with regard to the size and morphological characteristics of the prepared microspheres and their ability in preserving the antigenicity of the encapsulated TT, they could be used as a delivery system for mucosal delivery of TT.

Efficacy of the antiadhesin octyl O-(2-acetamido-2-deoxy-beta-D-galactopyranosyl)-(1-4)-2-O-propyl-beta-D-galactopyranoside (Fimbrigal-P) in a rat oral candidiasis model.

Adherence of Candida albicans to buccal epithelial cells via its fimbrial subunit requires the minimal disaccharide sequence beta-GalNAc(1-4)-beta-galactosidase in host cell receptors asialo-GM1 or asialo-GM2. This and other disaccharides and some of its synthetic derivatives have been shown to inhibit purified fimbrial or pathogen binding in vitro. This study evaluates the in vivo efficacy of the propyl derivative of this disaccharide, octyl O-(2-acetamido-2-deoxy-beta-D-galactopyranosyl)-(1-4)-2-O-propyl-beta-D-galactopyranoside, or Fimbrigal-P, incorporated into a mucoadhesive polymer formulation in a rat oral candidiasis model. Colony counts of microcurette samples from the oral cavity and tongue homogenates were used to estimate the effectiveness of four treatment modalities to reduce oral fungal burden. All treatment modalities (preventative, premixing with the Candida inoculant, drinking water, and treatment) significantly reduced fungal burden compared to untreated control animals by day 9; however, the preventative and pre-mixing approaches provided a faster rate of fungal clearance. The low toxicity and immunogenicity of this synthetic carbohydrate and its stability in saliva, as demonstrated by high-performance liquid chromatography, make it a promising candidate for the prevention and treatment of microbial infections in which the pathogen relies on the beta-GalNAc(1-4)-beta-galactosidase disaccharide to establish adherence.

Targeting of liposomes to melanoma cells with high levels of ICAM-1 expression through adhesive peptides from immunoglobulin domains.

The P(0) protein is an immunoglobulin [Ig] superfamily cell adhesion molecule from peripheral nerve myelin. Synthetic peptides derived from the P(0) protein and leukocyte function-associated antigen-1 (LFA-1) were investigated as potential ligands for targeting liposomes to intercellular adhesion molecule-1 (ICAM-1) expressing melanoma cells. Three synthetic P(0) peptides and one LFA-1 peptide were selected for linkage to liposome surfaces. P(0)-peptide-1, from the extracellular Ig-like domain, increased liposome binding to M21 (6.36-fold) and A-375 (1.85-fold) cells compared to control blank liposomes, but did not increase liposome binding to MeM 50-10 cells. P(0)-peptide-3, from the basic intracellular domain, increased binding of liposomes to all three melanoma cell lines nonspecifically due to its high content of positively charged amino acids. LFA-1- and negative control arg-gly-asp (RGD)-peptides did not affect liposome binding to M21 cells. The extent of P(0)-peptide-1-liposome binding to human melanoma cell lines correlated with the level of cellular ICAM-1 expression (r(2) = 0.868). P(0)-peptide-1-mediated targeting of liposomes might, therefore, prove useful in the development of drug delivery systems for treatment of ICAM-1 expressing malignant melanomas.

Targeting of liposomes to human keratinocytes through adhesive peptides from immunoglobulin domains in the presence of IFN-gamma.

T-cell adhesion is often dictated by the presence of intercellular adhesion molecule-1 (ICAM-1) on the target cell surface. Reconstitution of P(0) protein into liposomes increases adhesion to melanoma cells expressing ICAM-1. In our study, the effect of peptides derived from P(0) protein and leukocyte function associated-antigen 1 (LFA-1) on IFN-gamma-stimulated human keratinocytes was investigated. Covalently linked P(0)-peptide-1, from the Ig-like domain, increased specific liposome binding to IFN-gamma-stimulated keratinocytes in a dose-dependent manner. C-terminal-derived P(0)-peptide-3 increased liposome binding nonspecifically. LFA-1 and RGD peptides had no apparent effect. P(0)-peptide-1 is thus a potential targeting ligand for liposomal drug delivery to ICAM-1 expressing keratinocytes in inflammatory dermatoses.

P0 protein mediated targeting of liposomes to melanoma cells with high level of ICAM-1 expression.

The feasibility of targeting liposomes reconstituted with P0 protein (P0-liposomes) to melanoma cells with high level of intercellular adhesion molecule-1 (ICAM-1) expression was investigated. P0 protein, an immunoglobulin superfamily (IgSF) cell adhesion molecule from peripheral nerve myelin, was used as a model targeting ligand. Liposome uptake by the cells was quantitated using radioactive lipids. The presence of intact P0 protein in the liposome bilayer increased the extent of interaction of liposomes with human M21 (7.80 fold) and A-375 (4.62 fold) melanoma cells compared to control liposomes of same lipid composition but no P0 protein, whereas with MeM 50-10 melanoma cells no significant increase was found (1.70 fold). The extent of binding of P0-liposomes to the melanoma cells correlated with the level of ICAM-1 expression on cells (r2 = 0.9996). M21 and A-375 cells express ICAM-1 (the percentage of stained cells, PSC, was 95% and 85%, respectively), whereas, MeM 50-10 cells do not. P0 protein also increased the interaction of liposomes with P0 protein expressing CHO-X2 cells (4.36 fold, as a positive control) compared to control liposomes. The indirect flow cytometry experiments using biotinylated P0 protein showed that P0 protein itself in solution also binds to M21 cells but does not bind to MeM 50-10 cells. Preincubation of M21 cells with anti-ICAM-1 monoclonal antibody decreased the binding of biotinylated P0 protein to the M21 cells by 35%. P0 protein or its binding domain(s) that mediate the targeting of liposomes through adhesive interactions may be useful for the development of novel types of drug delivery systems. This approach may have relevance in the treatment of metastatic cancers, inflammation and viral diseases, where cell adhesion proteins are over expressed.