Preparation of Well-Defined Ibuprofen Prodrug Micelles by RAFT Polymerization

Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used to treat acute pain, fever, and inflammation and are being explored in a new indication in cancer. Side effects associated with long-term use of NSAIDs such as gastrointestinal damage and elevated risk of stroke, however, can limit their use and exploration in new indications. Here we report a facile method to prepare well-defined amphiphilic diblock copolymer NSAID prodrugs by direct reversible addition–fragmentation transfer (RAFT) polymerization of the acrylamide derivative of ibuprofen (IBU), a widely used NSAID. The synthesis and self-assembling behavior of amphiphilic diblock copolymers (PEG-PIBU) having a hydrophilic poly­(ethylene glycol) block and a hydrophobic IBU-bearing prodrug block were investigated. Release profiles of IBU from the micelles by hydrolysis were evaluated. Furthermore, the antiproliferative action of the IBU-containing micelles in human cervical carcinoma (HeLa) and murine melanoma (B16–F10) cells was assessed

Arginine-Based Biodegradable Ether–Ester Polymers with Low Cytotoxicity as Potential Gene Carriers

The success of gene therapy depends on safe and effective gene carriers. Despite being widely used, synthetic vectors based on poly­(ethylenimine) (PEI), poly­(l-lysine) (PLL), or poly­(l-arginine) (poly-Arg) are not yet fully satisfactory. Thus, both improvement of established carriers and creation of new synthetic vectors are necessary. A series of biodegradable arginine-based ether–ester polycations was developed, which consists of three main classes: amides, urethanes, and ureas. Compared to that of PEI, PLL, and poly-Arg, much lower cytotoxicity was achieved for the new cationic arginine-based ether–ester polymers. Even at polycation concentrations up to 2 mg/mL, no significant negative effect on cell viability was observed upon exposure of several cell lines (murine mammary carcinoma, human cervical adenocarcinoma, murine melanoma, and mouse fibroblast) to the new polymers. Interaction with plasmid DNA yielded compact and stable complexes. The results demonstrate the potential of arginine-based ether–ester polycations as nonviral carriers for gene therapy applications

Survival and function of encapsulated rat islets <i>in vitro</i>.

<p>Viability was assessed over 30 days in(green) and propidium iodide (red). Encapsulated islets remained viable over 30 days of culture. Scale bar 200 µm (A). The function of the encapsulated islets was tested in vitro 30 days post encapsulation by glucose stimulated insulin secretion test. Islets were incubated in medium with 2.8 mM glucose, 16.8 mM glucose and 16.8 mM glucose supplemented with theophylline. The stimulation index was respectively 2 (glucose-stimulated) and 5 (theophylline-stimulated). The mean and SEM are shown of one representative experiment out of three (B).</p

Encapsulated rat islets one month after transplantation.

<p>Encapsulated rat islets were transplanted under the kidney capsule (KC) (A–C) or into the bone marrow (BM) (D–F) One month after transplantation the femur and kidney were harvested. Haematoxylin and eosin staining showed intact capsules in the KC (A) and BM (D). Insulin staining confirmed the survival of the rat islets (B, E). The pericapsular fibrotic reaction was assessed by Masson’s coloration (C, F). The collagen/capsule surface ratio was quantified using MetaMorph software (G). Data presented are mean values ±SEM out of three (bone marrow) and four (kidney capsule) animals. Scale bar 100 µm (A,B,D,E), 1000 µm (C,F).</p

Characterization of the rejection in the bone marrow after rat islets transplantation.

<p>(A–C) Seven days post-transplantation, animals were sacrificed for the characterization of rejection. The graft-bearing femur (n = 5), the opposite control femur (n = 4) and the femur of non-transplanted animals (n = 4) were harvested, flushed and the cells analyzed by flow cytometry. The percentage of CD8⁺ (A) cells in transplanted femurs was significantly increased whereas percentages of CD4⁺ (B) and F4/80⁺ (C) cells remained unchanged compared to the non-transplanted contralateral control femurs. Box-and-whisker diagram are shown. (D–F) Alternatively, the femurs of graft bearing-femurs (D–F) and the contralateral femurs (G–I) were frozen in liquid nitrogen and double stained for insulin (green) and CD8 (D/G), CD4 (E/H) or F4/80 (F/I) (red) three days post transplantation. Scale bar 50 µm. (J) CD4⁺, CD8⁺ and F4/80⁺ cells were quantified using the MetaMorph software. The levels of CD4⁺ and F4/80⁺ cells were similar between both groups; CD8⁺ cells were significantly more abundant in femurs containing the islet graft. Abbreviation. Tx Cont: contralateral femur. TX D7: graft bearing femur.</p

Characterization of the splenocytes after rat islet transplantation into the bone marrow.

<p>The splenocytes of transplanted and naive animals were harvested seven days after transplantation. The absolute number of splenocytes was not significantly different compared to naive mice; data are shown for individual animals with the horizontal line representing the mean value (A). The percentages of CD4⁺, CD8⁺ and F4/80⁺ cells were not significantly different either. Box-and-whisker diagram are shown (B). However, splenocytes of transplanted mice showed a significantly increased level of proliferation compared to naive mice when stimulated by donor (T cell-depleted) rat irradiated splenocytes. Results are expressed in counts per minute and show the mean value of 4 naive and 6 transplanted animals (C). Abbreviation. Tx: transplanted. CPM: Count per minutes.</p

Transplantation of syngeneic islets into the bone marrow.

<p>A 22-gauge needle was used for injection of the syngeneic islets into the bone marrow of C57BL/6 through the distal part of the femur (A). Transplanted mice remained normoglycemic over 30 days (B). Intraperitoneal glucose tolerance test was performed after 30 days in transplanted and naïve mice. Error bars represent the standard deviation. (C). Bones were harvested after 30 days and stained for haematoxylin and eosin (D), insulin (E) and glucagon/insulin (F). Glucagon positive cells appear in red whereas insulin positive cells appear in green. Scale bar 500 µm (D,E), 100 µm (F).</p

Absence of a long-term trend in <i>s</i>_{<i>20T</i>,<i>t</i>,<i>r</i>,<i>v</i>}-values of the BSA monomer with time of experiment for the three kits (blue, green, and magenta).

<p>Highlighted as bold solid line is the overall average, and the grey area indicates one standard deviation.</p

Examples for the determination of radial magnification errors.

<p>(A) Radial intensity profile measured in scans of the precision mask. Blue lines are experimental scans, and shaded areas indicate the regions expected to be illuminated on the basis of the known mask geometry. In this example, the increasing difference between the edges corresponds to a calculated radial magnification error of -3.1%. (B—D) Examples for differences between the experimentally measured positions of the light/dark transitions (blue circles, arbitrarily aligned for absolute mask position) and the known edge distances of the mask. The solid lines indicate the linear or polynomial fit. (B) Approximately linear magnification error with a slope corresponding to an error of -0.04%. Also indicated as thin lines are the confidence intervals of the linear regression. (C) A bimodal shift pattern of left and right edges, likely resulting from out-of-focus location of the mask, with radial magnification error of -1.7%. (D) A non-linear distortion leading to a radial magnification error of -0.53% in the <i>s</i>-values from the analysis of back-transformed data. The thin grey lines in C and D indicate the best linear fit through all data points.</p

Analysis of the rotor temperature.

<p>(A) Temperature values obtained in different instruments of the spinning rotor, as measured in the iButton at 1,000 rpm after temperature equilibration, while the set point for the console temperature is 20°C (indicated as dotted vertical line). The box-and-whisker plot indicates the central 50% of the data as solid line, with the median displayed as vertical line, and individual circles for data in the upper and lower 25% percentiles. The mean and standard deviation is 19.62°C ± 0.41°C. (B) Correlation between iButton temperature and measured BSA monomer <i>s</i>-values corrected for radial magnification, scan time, scan velocity, but not viscosity (symbols). In addition to the data from the present study as shown in (A) (circles), also shown are measurements from the pilot study [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0126420#pone.0126420.ref027" target="_blank">27</a>] where the same experiments were carried out on instruments not included in the present study (stars). The dotted line describes the theoretically expected temperature-dependence considering solvent viscosity.</p