Pluronic Gel Research Articles

Development and in vitro evaluation of insulin-loaded buccal Pluronic F-127 gels

Insulin-loaded buccal Pluronic F-127 (PF-127) gel formulations were fabricated to study the effect of PF-127 concentration, insulin concentration, presence of salt, addition of polymer, and permeation enhancer on their gelation time, mucoadhesion force, release and permeation characteristics of insulin from the gels. Thereafter, the principle of statistical optimization to prepare a gel formulation having the potential for buccal delivery of basal insulin in diabetic patients was employed. The gelation time decreased as the concentration of PF-127 increased. Presence of salts as well as addition of polymer, such as methyl cellulose (MC) and hydroxypropylmethyl cellulose (HPMC) decreased the gelation time. An increase in PF-127 concentration and addition of MC and HPMC increased the mucoadhesion force of the gel formulations. Release and permeation of insulin from the gel formulations decreased with increased concentration of PF-127, presence of salts, and addition of MC and HPMC. Permeation of insulin from the optimized gel formulation was 93.17 (+/- 0.058, n = 3) microg/cm(2) which was not only found in close agreement with predicted results from the model equations used for the formulation optimization but also considered comparable to clinical setting. Therefore, the development of optimized buccal insulin-loaded Pluronic F-127 gels using a statistical experimental design is feasible.

On the Mechanism of Photochromism of 4′-N,N-Dimethylamino-7-hydroxyflavylium in Pluronic F127

The photochromism of the compound 4'-N,N-dimethylamino-7-hydroxyflavylium incorporated in Pluronic F127 micelles and gels was studied in great detail. The red flavylium ion (AH(+)) or the quinoidal base (A), depending on pH, are the irradiation products of the colorless trans-chalcone (Ct). Absorption and fluorescence (steady-state, time-resolved, and anisotropy), pH jumps, and flash photolysis were used to characterize the system. At moderately acidic to neutral pH values, the Ct species is distributed between the core and corona of the Pluronic micelle, as well as in the aqueous phase. At acidic pH values, AH(+) remains most probably in the water phase. The Ct maximum absorption wavelength constitutes a good sensor for the critical micelle concentration (CMC) or critical micelle temperature (CMT). The apparent acidity constant pK'(a) was found to be a relatively good sensor for CMC and also for detection of the sol-gel critical temperature. The Ct photochromic mechanism was analyzed by comparing the photophysics in pure solvents and the pluronic media. Solvatochromic effects show a lack of solvent polarity dependence of the Stokes shift, indicating a low dipolar moment change between the ground and the locally excited state. An internal charge transfer nonradiative process (ICT) competes with Ct photoisomerization and is the dominant process in highly polar solvents, preventing the appearance of photochromism, in contrast with lower polar environments, such as micelles and ethanol. In high viscous environments as those found in the core of the Pluronic F127 micelles or glycerol, both ICT and photoisomerization are reduced, enhancing the Ct fluorescence quantum yield. According to the data from fluorescence measurements and pH jumps, evidence for the Ct distribution among different sites within the pluronic aggregate was found, (i) a hydrophilic/fluid region where Ct has poor fluorescence and isomerization yields, bulk region; (ii) the corona of the micelle where photoisomerization is maximized; and (iii) the hydrophobic/viscous region where the fluorescence quantum yield is higher (and photoisomerization lower). This effect leads to a selective Ct photochemistry.

Single low-dose administration of pharmacological inhibitor of mitogen-activated ERK kinase to the adventitia of the injured rat carotid artery suppresses neointima formation and inhibits nuclear ERK signaling

Arterial injury has been reported to activate the mitogen-activated ERK kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling pathway. Pharmacological MEK inhibition was previously shown to inhibit injury-induced neointima formation in rodent models, but inhibitor compounds were administered either locally at a high dose or systemic treatment was performed over an extended period of time. Aim of this study was, therefore, to explore the efficiency of single low-dose administration of the MEK inhibitor PD98059 on neointima formation in the injured rat carotid artery. The second aim of the study was to analyse treatment effects on MEK-dependent signaling and protein expression. PD98059 (at doses of 10 and 40 nmol) was administered to the adventitia immediately after injury using Pluronic gel as drug carrier. Compared to untreated controls, PD98059 treatment (10 nmol) resulted in significant reductions of neointima-to-media ratio (by 66%) and injury-induced lumen loss (by 53%). Conversely, lumen was increased by 33% in PD98059-treated arteries. There were no significant differences between the 10 and 40 nmol treatment groups. Dual ERK1/2 phosphorylation, and also ERK1/2 protein expression, was significantly inhibited by PD98059 treatment. Expression of the transcription factor Ets-1, a nuclear target protein of ERK1/2 was significantly suppressed in PD98059-treated arteries. Attenuation of neointima formation was associated with significantly decreased expression of the proliferation marker PCNA. In contrast, we did not find biochemical evidence of increased apoptosis in PD98059-treated arteries. Our data show that the single adventitial administration of low-dose MEK inhibitor PD98059 is sufficient to suppress neointima formation in injured arteries.

Fibronectin Is an Important Regulator of Flow-Induced Vascular Remodeling

Fibronectin is an important regulator of cell migration, differentiation, growth, and survival. Our data show that fibronectin also plays an important role in regulating extracellular matrix (ECM) remodeling. Fibronectin circulates in the plasma and is also deposited into the ECM by a cell dependent process. To determine whether fibronectin affects vascular remodeling in vivo, we asked whether the fibronectin polymerization inhibitor, pUR4, inhibits intima-media thickening, and prevents excess ECM deposition in arteries using a mouse model of vascular remodeling. To induce vascular remodeling, partial ligation of the left external and internal carotid arteries was performed in mice. pUR4 and the control peptide were applied periadventitially in pluronic gel immediately after surgery. Animals were euthanized 7 or 14 days after surgery. Morphometric analysis demonstrated that the pUR4 fibronectin inhibitor reduced carotid intima (63%), media (27%), and adventitial thickening (40%) compared to the control peptide (III-11C). Treatment with pUR4 also resulted in a dramatic decrease in leukocyte infiltration into the vessel wall (80%), decreased ICAM-1 and VCAM-1 levels, inhibited cell proliferation (60% to 70%), and reduced fibronectin and collagen I accumulation in the vessel wall. In addition, the fibronectin inhibitor prevented SMC phenotypic modulation, as evidenced by the maintenance of smooth muscle (SM) alpha-actin and SM myosin heavy chain levels in medial cells. These data are the first to demonstrate that fibronectin plays an important role in regulating the vascular remodeling response. Collectively, these data suggest a therapeutic benefit of periadventitial pUR4 in reducing pathological vascular remodeling.

Injectable Superparamagnetic Ferrogels for Controlled Release of Hydrophobic Drugs

A ferrogel for magnetically controlled release of drugs is prepared by integration of superparamagnetic iron oxide nanoparticles and Pluronic F127 gels. The hydrophobic drug indomethacin is loaded in the ferrogel owing to the oil-in-water micellar structure. The characteristic sol–gel transition property renders the ferrogel an injectable drug carrier that will be, in principle, free from surgical implant procedure.

Novel fabrication of PCL porous beads for use as an injectable cell carrier system

Injectable polycaprolactone (PCL) porous beads were fabricated for use as cell carriers by a novel isolated particle-melting method (for nonporous beads) and the following melt-molding particulate-leaching method (for porous beads). The prepared beads showed highly porous and uniform pore structures with almost the same surface and interior porosities (porosity, over 90%). The PCL porous beads (bead size, 400-550 microm) with different pore sizes (25-50 and 50-100 microm) were compared for their in vitro cell (human chondrocyte) growth behavior with the nonporous beads. The porous beads showed higher cell seeding density and growth than the nonporous beads. The pore size effect between the porous beads was not significant up to 7 days, but after that time the beads with pore sizes of 50-100 microm showed significantly higher cell growth than those of 25-50 microm. To evaluate the tissue compatibility of the PCL porous beads, the beads were dispersed, uniformly, in cold Pluronic F127 solution and injected into hairless mice, subcutaneously, in the gel state of Pluronic F127 at room temperature, leading to the homogeneous bead delivery. The histological findings confirmed that the PCL porous beads in Pluronic F127 gel are biocompatible: surrounding tissues gradually infiltrated into the porous beads for up to 4 weeks with little inflammatory response. The PCL porous beads with highly porous and uniform pore structures fabricated in this study can be widely applicable as cell carriers.

Application of Pluronic gel to the study of root-knot nematode behaviour

Abstract Pluronic F-127 is a stable, non-toxic, copolymer that forms a gel at room temperature and a liquid at 15°C when the concentration is 20-30%. Root-knot nematode (Meloidogyne spp.) second-stage juveniles can move freely through the gel and display attraction toward roots of tomato, Medicago truncatula, common bean and Arabidopsis. The excellent clarity of the gel allows examination of behavioural changes in the nematode as it reaches and infects its host. Attraction assays showed that Meloidogyne javanica and M. incognita move to roots much more rapidly than does M. hapla. Nematodes form aggregates when in contact with root tips suggesting that the presence of a signal from the nematode or from the root is involved in the attraction. Nematodes suspended in Pluronic gel without roots aggregate into balls after 1 to 2 days. A coverslip placed on the gel accelerates and serves as a focus for the aggregation, suggesting that lower oxygen, or perhaps a volatile attractant, is involved in this behaviour. These observations demonstrate that Pluronic gel is a useful medium for dissecting attraction of root-knot nematodes to their hosts and for studying additional aspects of their behaviour.

Preparation, characterization, and in vitro release of new transdermal methimazole as alternative to oral delivery

Our objective has been the development and study of the stability of transdermal methimazole formulae as alternative to oral administration. Preparation of F-127 and PLO Pluronic gel (Pluronic lecitin organogel) are described, as well as their characteristics from transmission electron microscopy. The possible structural and rheological changes to both transdermal forms were studied in terms of composition, temperature and time. The trial period was from 24 hr to 3 months after preparation. Furthermore, identical tests were carried out on formulae conserved for 1 year after production to check their integrity. Studies of release in vitro were carried out showing that the selected excipients do not pose an obstacle to the cession of methimazole, even though the PLO samples were made more slowly.

Oligonucleotide Microarrays Reveal Regulated Genes Related to Inward Arterial Remodeling Induced by Urokinase Plasminogen Activator

Accumulating evidence suggests that urokinase plasminogen activator (uPA) is involved in vascular remodeling and lumen stenosis after angioplasty and stenting. We have shown previously that increased uPA expression greatly promotes neointima formation and inward arterial remodeling after balloon injury. To evaluate the role of inflammation in early mechanisms responsible for inward arterial remodeling induced by uPA and elucidate the mechanisms of remodeling, we characterized changes in the expression profiles of 8,799 genes in injured rat carotid arteries 1 and 4 days after recombinant uPA treatment compared to vehicle. We used a standard model of the balloon catheter injury of the rat carotid followed by periadventitial application to the injured vessel of either uPA dissolved in Pluronic gel, or plain gel. Vessels were harvested and analyzed by immunohistochemistry, morphometry, microarray gene expression profiling and quantitative RT-PCR. Periadventitial application of uPA significantly reduced lumen size and vessel area encompassed by the external elastic lamina at both 1 and 4 days after treatment. Inflammatory cells accumulated in the arterial adventitia at both 1 and 4 days after uPA treatment. On the 4th day, increases in the areas and arterial cell numbers of all arterial layers were found. Among 79 differentially expressed known genes 1 day after uPA application, 12 proinflammatory genes, including TNF-α and TACE, and 15 genes related to mitochondrial metabolism and oxidative stress regulation were identified. Four days after injury in uPA-treated arteries, 3 proinflammatory and 2 oxidation-related genes were differentially expressed. We conclude that uPA likely promotes inward arterial remodeling by regulating oxidative stress and inflammation after arterial injury.

Patterns of Gelatinase Activation Induced by Injury in the Murine Femoral Artery

Intimal hyperplasia remains the principal lesion in the development of restenosis after vessel wall injury. Modulation of the extracellular matrix by proteases is a pivotal component of the response to injury. The aim of this study is to characterize the changes in gelatinase (MMP-2/TIMP-2 and MMP-9/TIMP-1) systems in a murine model. The murine femoral wire injury model was used in which a microwire is passed through a branch of the femoral and used to denude the common femoral artery. Pluronic gel was used to apply a proteass inhibitor (GM6001) to the exterior of the vessels. Specimens were perfusion-fixed and sections were stained with hematoxylin and eosin and Movat's stain such that morphometry could be performed by using an ImagePro system. Additional specimens of femoral artery were also harvested and snap frozen for Western blotting and zymography to allow for the study of gelatinase expression and activation. Contralateral vessels were used as controls. MMP-2 activity increased significantly at day 1, peaked again at day 7, and then showed a continual decline in activity to day 56. MMP-9 activity peaked early at day 3 and declined thereafter. Protein expression for both MMP-2 and MMP-9 increased significantly after injury and both were maximal at day 14. There was an initial decrease in TIMP-1 and TIMP-2 expression and activity after injury until day 5. Both expression and activation gradually increased thereafter to level out by day 21 and correlated well with the early increases in MMP-2 and MMP-9 activity and their subsequent decline. Local application of protease inhibitor (GM6001) within a pluronic gel decreased cell proliferation, and at 14 d there was a decrease in intimal hyperplasia. These data demonstrate that femoral wire injury in the mouse is associated with a time-dependent increase in gelatinase activity. Cell proliferation is associated with increased MMP-2/MMP-9 activity and decreased TIMP-2/TIMP-1 activity, whereas migration is associated with increased in MMP-2 activity. Modulation of proteases and their inhibitors control the vessels' response to injury.

The effect of physiologically relevant additives on the rheological properties of concentrated Pluronic copolymer gels

The high concentration triblock copolymer poly(ethylene oxide)99–poly(propylene oxide)69–poly(ethylene oxide)99 (Pluronic F127) aqueous solutions with the addition of different components commonly used in physiologically relevant applications were characterized by rheological measurements, differential scanning calorimetry (DSC) and small angle X-ray/neutron scattering. The sol–gel transition temperature, as well as the storage modulus of the F127 solution depend both on the concentration of polymer and of clay. Above the gel transition, the storage modulus of the solutions increased with clay concentration. Yield strain is independent of polymer and clay concentrations. Two different kinds of inorganic salts, sodium chloride (NaCl) and calcium chloride (CaCl2) were added into the polymer and polymer–clay solutions. The sol–gel transition temperature decreased noticeably, but the storage modulus decreased only a small amount with increasing concentration of inorganic salts. Addition of salts to polymer–clay solutions resulted in precipitation of the clays which decreased the modulus. No effect on the mechanical properties was observed with the addition of common serum proteins. However, addition of 0.5–10% glucose decreased the transition temperature between 3° and 7°, without significantly affecting the modulus. The depression of the transition temperature by glucose was similar to that found with salts and indicated that the mechanism, namely competition for water, may be similar.

OLIGONUCLEOTIDE MICROARRAYS REVEAL REGULATED GENES RELATED TO INWARD ARTERIAL REMODELING INDUCED BY UROKINASE PLASMINOGEN ACTIVATOR

Accumulating evidence suggests that urokinase plasminogen activator (uPA) is involved in vascular remodeling and lumen stenosis after angioplasty and stenting. We have shown previously that increased uPA expression greatly promotes neointima formation and inward arterial remodeling after balloon injury. To evaluate the role of inflammation in early mechanisms responsible for inward arterial remodeling induced by uPA and elucidate the mechanisms of remodeling, we characterized changes in the expression profiles of 8,799 genes in injured rat carotid arteries 1 and 4 days after recombinant uPA treatment compared to vehicle. We used a standard model of the balloon catheter injury of the rat carotid followed by periadventitial application to the injured vessel of either uPA dissolved in Pluronic gel, or plain gel. Vessels were harvested and analyzed by immunohistochemistry, morphometry, microarray gene expression profiling and quantitative RT-PCR. Periadventitial application of uPA significantly reduced lumen size and vessel area encompassed by the external elastic lamina at both 1 and 4 days after treatment. Inflammatory cells accumulated in the arterial adventitia at both 1 and 4 days after uPA treatment. On

The oxidized phospholipid POVPC induces MMP3 expression and enhances migration of vascular smooth muscle cells

Oxidized phospholipids (oxPLs) including 1‐palmitoyl‐2‐(5‐oxovaleroyl)‐sn‐glycero‐3‐phosphoholine (POVPC) which are active components of minimally modified low density lipoprotein, are primary stimuli of multiple proatherogenic events. Previously we showed that oxPLs including POVPC induced profound phenotypic switching of vascular smooth muscle cells (VSMCs) including suppression of multiple SMC differentiation marker genes as well as activation of multiple inflammatory genes (Pidkovka et al, 2007, Circ Res). Little is known about the effects of oxPLs on genes that play a key functional role in the synthesis and degradation of extracellular matrix proteins that are critical in plaque formation and/or stability. Real time RT‐PCR, Western blot and Zymography analyses showed the increase of MMP3/stromelysin‐1 mRNA and protein level in cultured VSMCs after treatment with POVPC. Furthermore, POVPC‐induced elevation of MMP3 mRNA level was demonstrated in vivo after application of the pluronic gel containing POVPC to carotid arteries of rats. In addition, we found that POVPC enhances the VSMCs migration and invasion in Boyden chambers. The results provide new insights into the possible contribution of oxPLs to the atherogenesis through matrix degradation via MMP release and VSMCs migration leading to plaque destabilization and rupture. Supported by NIH grants R01 HL 38854, R37HL57353 and P01 HL19242.

Photochromic Soft Materials: Flavylium Compounds Incorporated into Pluronic F-127 Hydrogel Matrixes

The performance of flavylium-based photochromic systems is increased by their incorporation into Pluronic F-127 matrixes, which switch from polymeric solutions to micelles to gels with changes in temperature depending on copolymer concentration. Two flavylium compounds, 7,4'-dihydroxyflavylium and 7-(N,N-diethylamino)-4-hydroxyflavylium, both exhibiting a small thermal cis-trans isomerization barrier in water were investigated. In the first system the flavylium in the gel photoswitches from the colorless trans-chalcone (Ct) species to the yellow flavylium cation (AH+) with quantum yield Phi=0.04 (25 degrees C) at pH 2.2 or to the orange quinoidal base (A) with quantum yield Phi=0.015 (25 degrees C) at pH 5.2. The photoproducts revert back to their initial form by a thermal process characterized by first-order kinetics; the rate constants exhibit a bell shape variation with pH, with a maximum at pH 4.3 (lifetime 4.2 min). The second system, 7-(N,N-diethylamino)-4-hydroxyflavylium, does not exhibit photochemistry in water but, when incorporated into the Pluronic F-127 gel, switches from yellow to red with a quantum yield of Phi=0.01 at pH 4.9. The respective thermal back reaction takes place with a lifetime of 66.7 min1. The flavylium network of chemical reactions is a good sensor for the detection of not only the critical micelle temperature but also the gelation temperature of Pluronic and like solutions and, in some instances, the exposure to UV and visible radiation.

Molecular mechanisms linking wound inflammation and fibrosis: knockdown of osteopontin leads to rapid repair and reduced scarring

Previous studies of tissue repair have revealed osteopontin (OPN) to be up-regulated in association with the wound inflammatory response. We hypothesize that OPN may contribute to inflammation-associated fibrosis. In a series of in vitro and in vivo studies, we analyze the effects of blocking OPN expression at the wound, and determine which inflammatory cells, and which paracrine factors from these cells, may be responsible for triggering OPN expression in wound fibroblasts. Delivery of OPN antisense oligodeoxynucleotides into mouse skin wounds by release from Pluronic gel decreases OPN protein levels at the wound and results in accelerated healing and reduced granulation tissue formation and scarring. To identify which leukocytic lineages may be responsible for OPN expression, we cultured fibroblasts in macrophage-, neutrophil-, or mast cell–conditioned media (CM), and found that macrophage- and mast cell–secreted factors, specifically platelet-derived growth factor (PDGF), induced fibroblast OPN expression. Correspondingly, Gleevec, which blocks PDGF receptor signaling, and PDGF-Rβ–neutralizing antibodies, inhibited OPN induction by macrophage-CM. These studies indicate that inflammation-triggered expression of OPN both hinders the rate of repair and contributes to wound fibrosis. Thus, OPN and PDGF are potential targets for therapeutic modulation of skin repair to improve healing rate and quality.

Perivascular Delivery of Rapamycin in Pluronic Gel Inhibits Neointimal Hyperplasia in a Rat Carotid Artery Injury Model, and the Complementary Role of Carotid Arteriography

Background and Objectives: Rapamycin has been shown to inhibit the vascular smooth muscle cell migration and proliferation that contributes to neointimal formation. We investigated whether the perivascular delivery of rapamycin in Pluronic gel could inhibit neointimal hyperplasia in a rat carotid artery model, and we tested the usefulness of carotid arteriography. Materials and Methods: To assess the kinetics of rapamycin’s release from Pluronic gel, a [H] thymidine incorporation assay was performed with using the media exposed to rapamycin in Pluronic gel for 10, 20, 60 and 120 min. We applied 100 μg of rapamycin in Pluronic gel to the perivascular space of the carotid artery after the balloon injury (n=9), whereas only gel was applied in a control group (n=9). We performed the carotid arteriography and the morphometric analysis 14 days after injury. Results: The [H] thymidine incorporation assay showed a reduction of uptake in a time-dependent manner (86%, 48%, 45% and 40% of the control, respectively, at 10, 20, 60 and 120 minutes). The inhibiting effect of rapamycin on neointimal hyperplasia was identified on the carotid arteriography (mean luminal diameter; 0.75±0.11 vs. 0.60±0.12 arbitrary units, respectively, p<0.05) and on the morphometric analysis (neointima area: 0.09±0.03 vs. 0.17±0.06 mm, respectively, p<0.05). Conclusion: This study demonstrated that perivascular delivery of rapamycin in Pluronic gel inhibits neointimal hyperplasia in a rat carotid injury model. This animal model combined with arteriography can be used for developing new drugs to treat restenosis. In addition, this technique might be useful for vascular surgery such as coronary artery bypass grafting, arteriovenous fistula formation and peripheral vascular bypass graft insertion. (Korean Circ J 2008;38:80-86)

LIPOSOMAL GEL OF DICLOFENAC SODIUM AS TOPICAL DELIVERY SYSTEM

This study the preparation of diclofenac sodium in lecithin vesicles and loading in pluronic F-127 gel, the effect of sodium cholate on the diffusion of the drug through rat skin and the antiinflammatory activity of the liposomal gel formulations. Lecithin vesicles were prepared in the presence or absence of sodium cholate by the dry film method and sonication. The size of liposomal vesicles ranged from 100-700 nm and the encapsulation efficiency of the diclofenac sodium was between 60-80%. The lecithin vesicles were loaded in pluronic F-127 gel. The highest cumulative of drug diffusion through rat skin was 19.31± 1.50 (µg/cm2) for lecithin vesicles in the presence of sodium cholate (F4). Also the highest cumulative of drug diffusion through rat skin was 12.20± 0.50 (µg/cm2) for liposomal gel (F8). The antiinflammatory activity of the liposomal gel formulations was studied on carrageenan induced paw edema in rats. The results show that, F8 and F6 show superior anti-inflammatory activity in comparison with the other gel formulations. From the results, lecithin vesicles and liposomal gel of diclofenac sodium appear to be advantagesous for topical delivery of the drug.

Dual-role self-assembling nanoplexes for efficient gene transfection and sustained gene delivery

Novel cationic pentablock copolymers with poly(diethylamino ethyl methacrylate) blocks covalently attached to parent triblock Pluronic copolymers have been designed and developed as sustained release non-viral gene delivery vectors. These copolymers electrostatically condense plasmid DNA into nanostructures (nanoplexes) and further self-assemble above critical concentration to form thermoreversible hydrogels at physiological temperatures. Unlike other sustained gene delivery systems of non-ionic copolymers that release naked DNA, hydrogels of pentablock copolymer/DNA nanoplexes dissolve in excess buffers to release DNA compacted inside the nanoplexes. These hydrogels permit aqueous pharmaceutical formulations that do not involve organic solvents and are non-invasively injectable with syringes into localized tissues where they instantly form hydrogels in situ. The hydrogels were found to have better mechanical strength than Pluronic gels. Hydrogels of nanoplexes containing 15 wt% copolymer dissolved to release nanoplexes up to 5 days in vitro, compared to rapid release of up to 90% entrapped naked DNA from only Pluronic gels by day 1. The release profile of the nanoplexes from the hydrogels could be modulated by changing the concentration of copolymer or plasmid DNA in the hydrogel formulation. Since DNA is electrostatically bound to copolymer molecules, it does not freely diffuse out of the polymeric network, preventing initial release bursts observed with other such controlled release gels/matrices/microspheres. The released nanoplexes were colloidally stable, preserved the integrity of supercoiled plasmid DNA, and gave good transfection efficiencies in vitro upon dissolution. These novel copolymers, thus, act as both nanoscale gene delivery vectors and macroscale sustained delivery agents, and make a clinically viable long-term sustained gene delivery system.

First human experience with local delivery of novel antisense AVI-4126 with Infiltrator catheter in de novo native and restenotic coronary arteries: 6-month clinical and angiographic follow-up from AVAIL study

A novel antisense phosphorodiamidate morpholino oligomer, AVI-4126, was shown to be effective in reducing neointimal formation in different animal models following delivery by pluronic gels, porous balloon catheters, and coated stents. The purpose of the AVAIL study was to investigate both the safety and the efficacy of AVI-4126 delivered locally via Infiltrator catheter after percutaneous coronary intervention in humans. The AVAIL trial is a prospective, evaluator-blinded, randomized study including clinical follow-up at 30 days and 6 months after intervention and 6-month angiographic and intravascular ultrasound (IVUS) follow-up. An Infiltrator catheter was advanced to target lesion and either drug was delivered (Groups A and B) or catheter was advanced (Group C) after stent implantation in de novo lesions or percutaneous transluminal coronary angioplasty in restenotic lesions. Primary end points include major adverse cardiovascular events (MACE), target vessel revascularization (TVR), angiographic restenosis, and IVUS at 6 months. Forty-four patients with either de novo lesions or restenosis were randomized into three groups: (A) low dose, 3 mg (19 patients); (B) high dose, 10 mg (15 patients), and (C) control (10 patients). Baseline angiographic characteristics did not differ between the groups (reference vessel diameter, 2.5-4 mm; lesion length, <16 mm). Procedural success was 81. 82% (unable to advance Infiltrator catheter to target lesion in 8 patients, 5 from Group B and 3 from Group C). There was no in-hospital or 30-day MACE recorded in any group. Clinical follow-up was available in 25 patients. At 6 months, four patients (50%) from the control group (Group C, n=8) and 7 (100%) patients from the low-dose group (Group A, n=7) required TVR. In contrast, in the high-dose group (Group B, n=10) only 1 patient (10%) needed TVR. Angiographic follow-up in 25 patients (Group A, 8 patients; Group B, 7 patients; and Group C, 10 patients) demonstrated late loss of 1.4+ to 0.54, 0.8+ to 0.55, and 1.5+ to 0.65, respectively (P=.025). Binary restenosis was 38% in Group C (control), 29% in Group A (low dose), and 0% in Group B (high dose). Local delivery of antisense is feasible. These preliminary findings from the small cohort of patients require confirmation in a larger trial utilizing more sophisticated drug-eluting technologies.

Release Profile of BSA or BDNF from Temperature Sensitive Hydrogels

Methoxy poly(ethylene glycol) (MPEG)-b-poly(ε-caprolactone) (PCL) diblock copolymer was synthesized by ring-opening of ε-caprolactone (ε-CL) in the presence of a monomer activator with the terminal alcohol of MPEG as an initiator. The temperature sensitive behavior of the prepared MPEG-PCL diblock copolymer solution was examined. The polymer solution formed translucent sol at the room temperature. As the temperature increased from room temperature, the sol became gel, indicating that the diblock copolymer solution at room temperature can form gel at body temperature. Brain-derived neurotrophic factor (BDNF) loaded MPEG-PCL diblock copolymer solution and Pluronic solution for comparison were prepared to examine the release behavior of BDNF. Pluronic gel exhibited nearly complete release of BDNF even at 2 day, while the release of BDNF in MPEG-PCL gel showed the prolonged release profile for 21 days. In this study, we confirmed that thermosensitive MPEG-PCL diblock copolymer in this work could utilize as a potential carrier of BDNF.