Superior Drug Delivery Performance of Multifunctional Bilosomes: Innovative Strategy to Kill Skin Cancer Cells for Nanomedicine Application.

Purpose: Numerous failures in melanoma treatment as a highly aggressive form of skin cancer with an unfavorable prognosis and excessive resistance to conventional therapies are prompting an urgent search for more effective therapeutic tools. Consequently, to increase the treatment efficiency and to reduce the side effects of traditional administration ways, herein, it has become crucial to combine photodynamic therapy as a promising therapeutic approach with the selectivity and biocompatibility of a novel colloidal transdermal nanoplatform for effective delivery of hybrid cargo with synergistic effects on melanoma cells. Methods: The self-assembled bilosomes, co-stabilized with L-α-phosphatidylcholine, sodium cholate, Pluronic® P123, and cholesterol, were designated, and the stability of colloidal vesicles was studied using dynamic and electrophoretic light scattering, also provided in cell culture medium (Dulbecco's Modified Eagle's Medium). The hybrid compounds - a classical photosensitizer (Methylene Blue) along with a complementary natural polyphenolic agent (curcumin), were successfully co-loaded, as confirmed by UV-Vis, ATR-FTIR, and fluorescent spectroscopies. The biocompatibility and usefulness of the polymer functionalized bilosome with loaded double cargo were demonstrated in vitro cyto- and phototoxicity experiments using normal keratinocytes and melanoma cancer cells. Results: The in vitro bioimaging and immunofluorescence study upon human skin epithelial (A375) and malignant (Me45) melanoma cell lines established the protective effect of the PEGylated bilosome surface. This effect was confirmed in cytotoxicity experiments, also determined on human cutaneous (HaCaT) keratinocytes. The flow cytometry experiments indicated the enhanced uptake of the encapsulated hybrid cargo compared to the non-loaded MB and CUR molecules, as well as a selectivity of the obtained nanocarriers upon tumor cell lines. The phyto-photodynamic action provided 24h-post irradiation revealed a more significant influence of the nanoplatform on Me45 cells in contrast to the A375 cell line, causing the cell viability rate below 20% of the control. Conclusion: As a result, we established an innovative and effective strategy for potential metastatic melanoma treatment through the synergism of phyto-photodynamic therapy and novel bilosomal-origin nanophotosensitizers.

In Situ Sprayed Biotherapeutic Gel Containing Stable Microbial Communities for Efficient Anti-Infection Treatment.

Systematic administration of antibiotics to treat infections often leads to the rapid evolution and spread of multidrug-resistant bacteria. Here, an in situ-formed biotherapeutic gel that controls multidrug-resistant bacterial infections and accelerates wound healing is reported. This biotherapeutic gel is constructed by incorporating stable microbial communities (kombucha) capable of producing antimicrobial substances and organic acids into thermosensitive Pluronic F127 (polyethylene-polypropylene glycol) solutions. Furthermore, it is found that the stable microbial communities-based biotherapeutic gel possesses a broad antimicrobial spectrum and strong antibacterial effects in diverse pathogenic bacteria-derived xenograft infection models, as well as in patient-derived multidrug-resistant bacterial xenograft infection models. The biotherapeutic gel system considerably outperforms the commercial broad-spectrum antibacterial gel (0.1% polyaminopropyl biguanide) in pathogen removal and infected wound healing. Collectively, this biotherapeutic strategy of exploiting stable symbiotic consortiums to repel pathogens provides a paradigm for developing efficient antibacterial biomaterials and overcomes the failure of antibiotics to treat multidrug-resistant bacterial infections.

Tergitol-15-S-9 inactivates SARS-CoV-2 and boosts immunoassay signals.

Inactivation of SARS-CoV-2 virus is necessary to mitigate risk but may interfere with diagnostic assay performance. We examined the effect of heat inactivation on a prototype SARS-CoV-2 antigen immunoassay run on the ARCHITECT automated analyzer. Recombinant full-length SARS-CoV-2 nucleocapsid protein and virus lysate detection was reduced by 66 and 31%, respectively. Several nonionic detergents were assessed as inactivation alternatives based on infectivity in cultured Vero CCL81 cells. Incubation of SARS-CoV-2 in 0.1% Tergitol 15-S-9 for 10 min significantly reduced infectivity and increased the immunoassay signal for cultured lysate and patient specimens. Tergitol 15-S-9 can inactivate SARS-CoV-2 while preserving epitopes on the nucleocapsid protein for enhanced detection by immunoassay antibodies.

Improving Treatment Efficacy of In Situ Forming Implants via Concurrent Delivery of Chemotherapeutic and Chemosensitizer.

P-glycoprotein (Pgp), a member of the ATP-binding cassette family, is one of the major causes of multidrug resistance in tumors. Current clinical treatments to overcome MDR involve the co-delivery of a Pgp inhibitor and a chemotherapeutic. A concern for this treatment that has led to varied clinical trial success is the associated systemic toxicities involving endogenous Pgp. Local drug delivery systems, such as in situ forming implants (ISFIs), alleviate this problem by delivering a high concentration of the drug directly to the target site without the associated systemic toxicities. ISFIs are polymeric drug solutions that undergo a phase transition upon injection into an aqueous environment to form a solid drug eluting depot allowing for a high initial intratumoral drug concentration. In this study, we have developed an ISFI capable of overcoming the Pgp resistance by co-delivering a chemotherapeutic, Doxorubicin (Dox), with a Pgp inhibitor, either Pluronic P85 or Valspodar (Val). Studies investigated in vitro cytotoxicity of Dox when combined with either Pgp inhibitor, effect of the inhibitors on release of Dox from implants in PBS, in vivo Dox distribution and retention in a subcutaneous flank colorectal murine tumor, and therapeutic response characterized by tumor growth curves and histopathology. Dox + Val showed a 4-fold reduction in the 50% lethal dose (LD50) after 48 hours. Concurrent delivery of Dox and Val showed the greatest difference at 16 days post injection for both Dox penetration and retention. This treatment group had a 5-fold maximum Dox penetration compared to Dox alone ISFIs (0.53 ± 0.22 cm vs 0.11 ± 0.11 cm, respectively, from the center of the ISFI). Additionally, there was a 3-fold increase in normalized total intratumoral Dox intensity with the Dox + Val ISFIs compared to Dox alone ISFIs (0.54 ± 0.11 vs 0.18 ± 0.09, respectively). Dox + Val ISFIs showed a 2-fold reduction in tumor growth and a 27.69% increase in necrosis 20 days post-injection compared to Dox alone ISFIs. These findings demonstrate that co-delivery of Dox and Val via ISFI can avoid systemic toxicity issues seen with clinical Pgp inhibitors.

pH-sensitive pluronic micelles combined with oxidative stress amplification for enhancing multidrug resistance breast cancer therapy.

Multidrug resistance (MDR) is one of the major obstacles to clinical cancer chemotherapy. Herein, we designed new pH-sensitive pluronic micelles with the synergistic effects of oxidative therapy and MDR reversal. Pluronic (P123) was modified with α-tocopheryl succinate (α-TOS) via an acid-labile ortho ester (OE) linkage to give a pH-sensitive copolymer (POT). Self-assembled POT micelles exhibited desirable size (~80 nm), excellent anti-dilution ability, high drug loading (~85%), acid-triggered degradation and drug release behaviours. In vitro cell experiments verified that POT micelles could significantly reverse MDR through suppressing the function of drug effluxs mediated by P123 and induce more reactive oxygen species (ROS) generation mediated by α-TOS, resulting in enhanced cytotoxicity and apoptosis in MDR cells. In vivo studies further revealed that DOX-loaded POT micelles (POT-DOX) possessed the highest drug accumulation (3.03% ID/g at 24 h) and the strongest tumour growth inhibition (TGI 83.48%). Pathological analysis also indicated that POT-DOX could induce more apoptosis or necrosis at the site of tumour without distinct damage to normal tissues. Overall, these smart POT micelles have great potential as promising nano-carriers for MDR reversal and cancer treatment.

Selective Photodynamic Effects on Breast Cancer Cells Provided by p123 Pluronic®- Based Nanoparticles Modulating Hypericin Delivery.

BACKGROUND: Breast cancer is the most relevant type of cancer and the second cause of cancer- related deaths among women in general. Currently, there is no effective treatment for breast cancer although advances in its initial diagnosis and treatment are available. Therefore, the value of novel anti-tumor therapeutic modalities remains an immediate unmet need in clinical practice. Following our previous work regarding the properties of the Pluronics with different photosensitizers (PS) for photodynamic therapy (PDT), in this study we aimed to evaluate the efficacy of supersaturated hypericin (HYP) encapsulated on Pluronic® P123 (HYP/P123) against breast cancer cells (MCF-7) and non-tumorigenic breast cells (MCF-10A). METHODS: Cell internalization and subcellular distribution of HYP/P123 was confirmed by fluorescence microscopy. The phototoxicity and citototoxicity of HYP/P123 was assessed by trypan blue exclusion assay in the presence and absence of light. Long-term cytotoxicity was performed by clonogenic assay. Cell migration was determined by the wound-healing assay. Apoptosis and necrosis assays were performed by annexin VFITC/ propidium Iodide (PI) by fluorescence microscopy. RESULTS: Our results showed that HYP/P123 micelles had high stability and high rates of binding to cells, which resulted in the selective internalization in MCF-7, indicating their potential to permeate the membrane of these cells. Moreover, HYP/P123 micelles accumulated in mitochondria and endoplasmic reticulum organelles, resulting in the photodynamic cell death by necrosis. Additionally, HYP/P123 micelles showed effective and selective time- and dose dependent phototoxic effects on MCF-7 cells but little damage to MCF-10A cells. HYP/P123 micelles inhibited the generation of cellular colonies, indicating a possible capability to prevent the recurrence of breast cancer. We also demonstrated that HYP/P123 micelles inhibit the migration of tumor cells, possibly by decreasing their ability to form metastases. CONCLUSION: Taken together, the results presented here indicate a potentially useful role of HYP/P123 micelles as a platform for HYP delivery to more specifically and effectively treat human breast cancers through photodynamic therapy, suggesting they are worthy for in vivo preclinical evaluations.

Cilostazol-loaded electrospun three-dimensional systems for potential cardiovascular application: Effect of fibers hydrophilization on drug release, and cytocompatibility.

Currently marketed drug-eluting stents are non-selective in their anti-restenotic action. New active substance introduction to polymeric stents and vascular grafts can promote early re-endothelialization, crucial in preventing implant restenosis. Additionally, managing material hydrophobicity by blending synthetic polymers limits adverse effects on bulk properties and controls active substance release. However, the influence of hydrophilic synthetic polymer on human cells in the cardiovascular system remains to be determined. In this report, effects of both poly(ε-caprolactone) (PCL) fibers hydrophilization with Pluronic P123 (P123) and cilostazol (CIL) loading were studied. Physicochemical and mechanical properties of electrospun tubular structures produced from PCL and PCL/P123 fibers with and without CIL were investigated and compared. Release profiles studies and in vitro cell proliferation assays of electrospun materials were conducted. It was found that P123 located near the surface of electrospun fibers increased the rate of CIL release. PCL formulation sustained human umbilical vein endothelial cells (HUVEC) growth for 48 h. Despite improved hydrophilicity, PCL/P123 formulations were found to reduce HUVEC viability. Both PCL and PCL/P123 materials reduced primary aortic smooth muscle cells (PASM) viability after 48 h. In PCL formulations containing CIL, drug release caused a decrease in PASM viability. P123 blending with PCL was found to be as a useful pre-fabrication technique for modulating surface hydrophobicity of electrospun materials and the release profile of incorporated active substance. The cytotoxicity of P123 was evaluated to improve the design of drug-loaded vascular grafts for cardiovascular applications.

Enhanced delivery of sorafenib with anti-GPC3 antibody-conjugated TPGS-b-PCL/Pluronic P123 polymeric nanoparticles for targeted therapy of hepatocellular carcinoma.

Although sorafenib (SFB) showed improved efficacy and much reduced the side effects in clinical liver cancer therapy, its therapeutic efficacy was still greatly limited due to short half-life in vivo as well as drug resistance. To solve these problems, we developed a novel SFB-loaded polymeric nanoparticle for targeted therapy of liver cancer. This polymeric nanoparticle, referred to NP-SFB-Ab, was fabricated from self-assembly of biodegradable block copolymers TPGS-b-poly(caprolactone) (TPGS-b-PCL) and Pluronic P123 and drug SFB, followed by conjugating the anti-GPC3 antibody. NP-SFB-Ab showed robust stability and achieve excellent SFB release in cell medium. The CLSM demonstrated that the Ab-conjugated NP exhibited much higher cellular uptake in HepG2 human liver cells than non-targeted NP. The MTT assay also confirmed that NP-SFB-Ab caused much greater cytotoxicity than non-targeted NP-SFB and free SFB. Finally, NP-SFB-Ab was proved to greatly inhibit the tumor growth of HepG2 xenograft-bearing nude mice without obvious side effects. Therefore, this NP-SFB-Ab provides a promising new approach for targeted therapy of hepatocellular carcinoma.

Poloxamer P85 increases anticancer activity of Schiff base against prostate cancer in vitro and in vivo.

Prostate cancer is the second most common cancer among men and the leading cause of death after lung cancer. Development of hormone-refractory disease is a crucial step for prostate cancer progression for which an effective treatment option is currently unavailable. Therefore, there is a need for new agents that can efficiently target cancer cells, decrease tumor growth, and thereby extend the survival of patients in late-stage castration-resistant prostate cancer. In the current study, a novel heterodinuclear copper(II)Mn(II) Schiff base complex combined with P85 was used to evaluate anticancer activity against prostate cancer in vitro and in vivo. Cell proliferation and cytotoxicity were evaluated by cell viability, gene, and protein expression assays in vitro. Results showed that the heterodinuclear copper(II)Mn(II) complex-P85 combination decreased cell proliferation by upregulating the apoptotic gene expressions and blocking the cell proliferation-related pathways. Tramp-C1-injected C57/B16 mice were used to mimic a prostate cancer model. Treatment combination of Schiff base complex and P85 significantly enhanced the cellular uptake of chemicals (by blocking the drug transporters and increased life time), suppressed tumor growth, and decreased tumor volume steadily over the course of the experiments. Overall, heterodinuclear copper(II)Mn(II) complex-P85 showed remarkable anticancer activity against prostate cancer in in vitro and in vivo.

Multifunctional theranostic Pluronic mixed micelles improve targeted photoactivity of Verteporfin in cancer cells.

Nanotechnology development provides new strategies to treat cancer by integration of different treatment modalities in a single multifunctional nanoparticle. In this scenario, we applied the multifunctional Pluronic P123/F127 mixed micelles for Verteporfin-mediated photodynamic therapy in PC3 and MCF-7 cancer cells. Micelles functionalization aimed the targeted delivery by the insertion of biotin moiety on micelle surface and fluorescence image-based through rhodamine-B dye conjugation in the polymer chains. Multifunctional Pluronics formed spherical nanoparticulated micelles that efficiently encapsulated the photosensitizer Verteporfin maintaining its favorable photophysical properties. Lyophilized formulations were stable at least for 6months and readily reconstituted in aqueous media. The multifunctional micelles were stable in protein-rich media due to the dual Pluronic mixed micelles characteristic: high drug loading capacity provided by its micellar core and high kinetic stability due its biocompatible shell. Biotin surface functionalized micelles showed higher internalization rates due biotin-mediated endocytosis, as demonstrated by competitive cellular uptake studies. Rhodamine B-tagged micelles allowed monitoring cellular uptake and intracellular distribution of the formulations. Confocal microscopy studies demonstrated a larger intracellular distribution of the formulation and photosensitizer, which could drive Verteporfin to act on multiple cell sites. Formulations were not toxic in the dark condition, but showed high Verteporfin-induced phototoxicity against both cancer cell lines at low drug and light doses. These results point Verteporfin-loaded multifunctional micelles as a promising tool to further developments in photodynamic therapy of cancer.

Examination of Gossypol-Pluronic Micelles as Potential Radiosensitizers.

Chemoradiotherapy, the combination of chemotherapy and radiotherapy to treat cancer, has the potential to enhance local therapeutic effects and simultaneously treat systemic disease. However, chemoradiotherapy may also enhance normal tissue effects leading to both acute and late toxicities. Furthermore, subtherapeutic chemoradiotherapy may result in aggressive tumor repopulation. Tumor-specific radiosensitizing chemotherapy may yield a synergistic therapeutic effect and avoid augmentation of normal tissue toxicity. In this study, the radiosensitizing effects of gossypol were investigated. Also, Pluronics were studied for gossypol solubilization and co-radiosensitization effects. Gossypol inhibits Bcl-2 and Bcl-XL, antiapoptotic proteins that are overexpressed in various cancer cells. Pluronic micelles (P85, F88, L35, and P123) effectively encapsulated gossypol, raising its water solubility by more than 1000-fold. Cytotoxic, anticlonogenic, and radiosensitizing effects were evaluated to characterize gossypol and Pluronic combinations. Gossypol and P85 had the strongest antiproliferative effect on A549 human lung adenocarcinoma cells in a cell viability assay. The IC50 value was seven times lower than gossypol only treatment (330 ± 70 nM vs 2400 ± 400 nM, (mean ± SE)). Gossypol and P85 showed significant inhibition of clonogenic survival, approximately 30% inhibition, compared to treatment with gossypol alone. An experimental sequencing study demonstrated greater inhibition of clonogenic survival when drug treatment followed radiation compared to a sequence of drug treatment followed by radiation. These results suggest that Pluronic micelles readily solubilize gossypol and that the combination of gossypol and P85 may augment the therapeutic effects of ionizing radiation.

Oleochemical-tethered SBA-15-type silicates with tunable nanoscopic order, carboxylic surface, and hydrophobic framework: cellular toxicity, hemolysis, and antibacterial activity.

Novel silicates were prepared by using silylated natural fatty acids (derived from triglyceride renewable oils) as co-condensing reagents in presence of tetraethyl orthosilicate (TEOS) and the triblock copolymer, pluronic P123, as a structure directing agent. A series of carboxylic acid functionalized SBA-15-type mesoporous silicates were obtained with tunable nanoscopic order and reactive functional groups that allow the conjugation of amino probes by peptide coupling. Photophysical studies of the covalently linked aminopyrene substantiated that the internal framework of these materials have pronounced hydrophobicity. Moreover, phase separation that can emanate from the bulkiness of the starting fatty silanes has been ruled out owing to the absence of excimers after aminopyrene grafting. The hemotoxicity, cytotoxicity, and antimicrobial activity of these novel silicates were then evaluated. Without discrimination, the functionalized silicates show a significant decrease of red blood cell hemolysis as compared to bare SBA-15-silica material. Within the modified silicate series, germanium-free mesoporous silicates induce only a slight decrease in cell viability and, more interestingly, they exhibit negligible hemolytic effect. Moreover, increasing their concentration in the medium reduces the concentration of released hemoglobin as a result of Hb adsorption. Promising antimicrobial properties were also observed for these silicates with a slight dependency on whether phenylgermanium fragments were present within the silicate framework.

Effect of F68, F127, and P85 pluronic block copolymers on odontogenic differentiation of human tooth germ stem cells.

INTRODUCTION: The major challenge in dental pulp engineering is to make a successful combination of stem cells and biomaterials with the aim of providing the differentiation of stem cells into odontogenic cell types. Among biomaterials, some types of pluronics have been reported to increase bone formation of stem cells. The effect of these pluronics on odontogenic differentiation has not been addressed yet. This study aimed to examine the effect of pluronics F68, F127, and P85 on odontogenic differentiation of stem cells derived from third molar tooth germs of young adults. METHODS: Human tooth germ stem cells (hTGSCs) were induced to differentiate into odontogenic cells in the presence of different concentrations of pluronics. Differentiation efficiency was assessed by quantitative real-time polymerase chain reaction for determining expression messenger RNA levels and by immunocytostaining for determining the protein expression of odontogenic markers (ie, dentin sialoprotein, dentin matrix protein 1, bone morphogenic protein 2, bone morphogenic protein 7) by measuring alkaline phosphatase enzyme activity and lastly by von Kossa staining for determining mineralization. RESULTS: The results revealed for the first time that F68 has a great potential to boost odontogenic differentiation of hTGSCs. P85 was found to reduce cell viability during differentiation. F127 was nontoxic to hTGSCs but did not have any effect on differentiation. CONCLUSIONS: The positive effect of F68 on odontogenic differentiation might enable more efficient pulp regeneration. Yet, the exact mechanism of how F68 alters the differentiation pattern of hTGSCs remains to be investigated in the future studies.

Effects of surfactants on cell surface tension parameters and hydrophobicity of Pseudomonas putida 852 and Rhodococcus erythropolis 3586.

The interaction between bacteria and surfaces is central to many environmental, industrial and medical applications. Surfactants are commonly used in these applications and can potentially influence the bacterium/surface interaction. The effect of surfactants upon bacterial cell surface thermodynamic properties was examined using a combination of contact angle measurements and LW-AB surface free energy calculation. Two bacterial strains, hydrophilic Pseudomonas putida 852 and hydrophobic Rhodococcus erythropolis 3586, and two surfactant types, the anionic biosurfactant rhamnolipid and the non-ionic chemical surfactant tergitol, were examined. The study demonstrated that surfactant treatment could modify cell surface tension parameters including Lifshitz-van der Waals (γ(LW)), electron-donor (γ(-)) and electron-acceptor (γ(+)) and thereby the bacterial cell hydrophobicity, depending on the surfactant type and concentration and the bacterial surface characteristics. Rhamnolipid and tergitol were found to increase P. putida 852 hydrophobicity, but decrease the hydrophobicity of R. erythropolis 3586. The extent of change was dependent on surfactant concentration. Among the three surface tension parameters, γ(-) was found to be the most important in predicting bacterial cell hydrophobicity.

[Mechanisms of human plasma proteins adsorption on the surface of perfluorocarbon emulsion stabilized with proxanol 268].

It has been shown that sorption of most proteins with the molecular weight lower than 200 kDa from human blood plasma on the surface of perfluorocarbon emulsion, stabilized with proxanol 268, is mainly based on hydrophobic interaction, whereas sorption of immunoglobulin G is mainly the result of electrostatic interaction. The removal of lipidic components from plasma leads to the increase of a total amount of adsorbed proteins by 35%. Particularly, when lipidic components are removed, sorption of apolipoprotein AI and immunoglobulin G is considerably bettered as well as sorption of other proteins with the molecular weight of about 50 and 60 kDa occurs. It has been out that apolipoprotein AI in the adsorbed condition loses its capability of tryptophan fluorescence, which might be probably determined by the quenching influence of the perfluorocarbon core of nanoparticle. We think that the findings obtained also indicates considerable conformational rearrangements of this protein during adsorption. It was shown, that the fluorescence of proteins with sorption on nanoparticles in emulsion based on the hydrophobic interaction, is completely or partially quenched.

[Blood plasma protein adsorption capacity of perfluorocarbon emulsion stabilized by proxanol 268 (in vitro and in vivo studies)].

The adsorption abilities of the perfluorocarbon emulsion stabilized by Proxanol 268 were investigated in vitro and in vivo. In vitro, the saturation point for the blood plasma proteins was nearly reached after five minutes of incubation of the emulsion with human/rabbit blood plasma and was stable for all incubation periods studied. The decrease in volume ratio (emulsion/plasma) was accompanied by the increase in the adsorptive capacity of the emulsion with maximal values at 1/10 (3.2 and 1.5 mg of proteins per 1 ml of the emulsion, for human and rabbit blood plasma, respectively) that was unchanged at lower ratios. In vivo, in rabbits, intravenously injected with the emulsion, the proteins with molecular masses of 12, 25, 32, 44, 55, 70, and 200 kDa were adsorbed by the emulsion (as in vitro) if it was used 6 hours or less before testing. More delayed testing (6 h) revealed elimination of proteins with molecular masses of 25 and 44 kDa and an additional pool of adsorpted new ones of 27, 50, and 150 kDa. Specific adsorptive capacity of the emulsion enhanced gradually after emulsion injection and reached its maximum (3.5-5 mg of proteins per 1 ml of the emulsion) after 24 hours.

Preparation and evaluation of folate-modified cationic pluronic micelles for poorly soluble anticancer drug.

The aim of this study was to construct novel targeting polymeric micelles. Folate-Poly (ethylenimine)-Pluronic copolymers were synthesized. A paclitaxel (PTX)-loaded mixed micelles consisting of Folate-Poly (ethylenimine)-Pluronic and Pluronic L121 copolymers have been developed. The mixed micelles showed nano-sized spherical morphology. The solubilization capacity of the mixed micelles was higher than Folate-Poly (ethylenimine)-Pluronic micelles because L121 has high solubilization capacity. MTT colorimetric test revealed that PTX in Folate-Poly (ethylenimine)-Pluronic micelles demonstrated the maximum anticancer activity. Pluronic-poly (ethylenimine) micelles and folate-modified Pluronic-poly(ethylenimine) micelles showed a marked increase of cellular accumulation compared with Pluronic P123 micelles. The biodistribution and retention of intravenously (i.v.) administered micelles to rats were determined. Folate-Poly (ethylenimine)-Pluronic micelles demonstrated enhanced pulmonary retention in rats after injection when compared to Pluronic P123 micelles.

Chylomicron formation and secretion is required for lipid-stimulated release of incretins GLP-1 and GIP.

Glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) are incretins produced in the intestine that play a central role in glucose metabolism and insulin secretion. Circulating concentrations of GLP-1 and GIP are low and can be difficult to assay in rodents. These studies utilized the novel intestinal lymph fistula model we have established to investigate the mechanism of lipid-stimulated incretin secretion. Peak concentrations of GLP-1 and GIP following an enteral lipid stimulus (Liposyn) were significantly higher in intestinal lymph than portal venous plasma. To determine whether lipid-stimulated incretin secretion was related to chylomicron formation Pluronic L-81 (L-81), a surfactant inhibiting chylomicron synthesis, was given concurrently with Liposyn. The presence of L-81 almost completely abolished the increase in lymph triglyceride seen with Liposyn alone (P < 0.001). Inhibition of chylomicron formation with L-81 reduced GLP-1 secretion into lymph compared to Liposyn stimulation alone (P = 0.034). The effect of L-81 relative to Liposyn alone had an even greater effect on GIP secretion, which was completely abolished (P = 0.004). These findings of a dramatic effect of L-81 on lymph levels of GLP-1 and GIP support a strong link between intestinal lipid absorption and incretin secretion. The relative difference in the effect of L-81 on the two incretins provides further support that nutrient-stimulation of GIP and GLP-1 is via distinct mechanisms.

Combined pluronic P85- and ultrasound contrast agents-mediated gene transfection to HepG2 cells.

This study examined the effect of P85 (a pluronic block copolymer) and microbubble (MB) ultrasound contrast agents under ultrasound irradiation on gene transfection and expression. The pEGFP plasmids that can encode enhanced green fluorescent protein (pEGFP) served as a report gene and were mixed with different concentrations of MB/0.05% (w/v) P85. Then the plasmids were transfected into human hepatoma G2 (HepG2) cells. The HepG2 cells treated with MB/P85 or without treatment were exposed to ultrasound (US parameters: 1 MHz, 1.0 W/cm(2), 20 s, 20% duty cycle). Twenty-four hours later, the transfection efficiency was assessed by fluorescence microscopy and fluorescence activated cell sorting (FACS) analysis. The cell viability was evaluated by Trypan blue exclusion test. The results showed that the gene transfection efficiency in HepG2 cells under ultrasound irradiation was significantly higher than that without ultrasound irradiation. HepG2 cells in the MB or P85 group in the absence of ultrasound expressed less amount of green fluorescent protein. The expression efficiency reached (22.14 ± 3.06)% and the survival rate was as high as (55.73 ± 3.32)% in the 30% MB plus P85 group. It was concluded that MB and P85 in the presence of ultrasound can enhance gene transfection and expression.

Effect of pluronic P123 and F127 block copolymer on P-glycoprotein transport and CYP3A metabolism.

The aim of the present study was to evaluate the effect of pluronic P123 (P123) and pluronic F127 (F127) on intestinal P-glycoprotein (P-gp) and cytochrome P450 3A using the specific substrates rhodamine-123 (R-123) and midazolam, respectively. Caco-2 cells and everted gut sacs were used as models of intestinal mucosa to assess intestinal absorption of R-123, while rat intestinal microsomes were utilized to examine the effect of P123 and F127 on in vitro midazolam metabolism. P123 and F127 were observed to increase the intracellular accumulation of R-123 in Caco-2 cells in a dose-dependent manner. P123 significantly lowered the efflux ratio of R-123 at two concentrations in Caco-2 monolayers, whereas F127 lowered the efflux ratio only at 1%. Moreover, both pluronics markedly enhanced mucosal to serosal absorption of R-123 in excised ileum of rats. However, no significant difference in relative enzyme activity were observed between P123- or F127-treated and control groups, regardless of the concentrations of P123 and F127 studied. Collectively, these results obtained from the present study demonstrated that P123 and F127 were capable of inhibiting the intestinal P-gp activity, but had little or no effect on intestinal cytochrome P450 3A activity, indicating that P123 and F127 can potentially be used as pharmaceutical ingredients to improve the oral bioavailability of coadministered P-gp substrates via P-gp efflux pump inhibition.