Monthly Archives: August 2014

PolySciTech Kito-6 used to assay bat insect digestion mechanism by chitinolytic activity

PolySciTech (www.polyscitech.com) provides a wide array of polymers including specially modified chitosans. One of the distributed products we carry is thermogelling glyol chitin. A recent publication utilizes this material to assay the capability of bat lysozymes to degrade chitin (essentially bats capacity to digest chitin, which is found in insect exoskeletons that serves as their food). Read more: Liu, Yang, Guimei He, Huihui Xu, Xiuqun Han, Gareth Jones, Stephen J. Rossiter, and Shuyi Zhang. “Adaptive Functional Diversification of Lysozyme in Insectivorous Bats.” Molecular Biology and Evolution (2014): msu240. http://mbe.oxfordjournals.org/content/early/2014/08/18/molbev.msu240.short

“Abstract: The role of gene duplication in generating new genes and novel functions is well recognized and is exemplified by the digestion-related protein lysozyme. In ruminants, duplicated chicken-type lysozymes facilitate the degradation of symbiotic bacteria in the foregut. Chicken-type lysozyme has also been reported to show chitinase-like activity, yet no study has examined the molecular evolution of lysozymes in species that specialize on eating insects. Insectivorous bats number over 900 species, and lysozyme expression in the mouths of some of these species is associated with the ingestion of insect cuticle, suggesting a chitinase role. Here we show that chicken-type lysozyme has undergone multiple duplication events in a major family of insect-eating bats (Vespertilionidae) and that new duplicates have undergone molecular adaptation. Examination of duplicates from two insectivorous bats – Pipistrellus abramus and Scotophilus kuhlii – indicated that the new copy was highly expressed in the tongue, whereas the other one was less tissue-specific. Functional assays applied to pipistrelle lysozymes confirmed that, of the two copies, the tongue duplicate was more efficient at breaking down glycol chitin, a chitin derivative. These results suggest that the evolution of lysozymes in vespertilionid bats has likely been driven in part by natural selection for insectivory.”

Missed this year’s CRS meeting? Get a Free PolySciTech T-Shirt with order

PolySciTech (www.polyscitech.com) provides a wide array of biodegradable polymers and related research products. At this year’s CRS meeting we handed out over 300 T-shirts to scientists and students to show that they live a radical life by working with polymers. Starting today any orders placed with an order total of $1000 or more will receive a free size-large T-shirt. Also keep your eyes open for upcoming prize photo and slogan contests.PolySciTech Shirt giveaway-small

PLGA microparticles investigated for improving vaccine response

PolySciTech (www.polyscitech.com) provides a wide array of PLGA polymers and related block copolymers. Recent research with PLGA’s have found that lipid-coated microparticles of PLGA that have antigen present on the surface cause a strong immune response in mice due to their ability to shed the lipid layer antigens into the lymph nodes. Read more: Hanson, Melissa C., Anna Bershteyn, Monica P. Crespo, and Darrell J. Irvine. “Antigen delivery by lipid-enveloped PLGA microparticle vaccines mediated by in situ vesicle shedding.” Biomacromolecules (2014). http://pubs.acs.org/doi/abs/10.1021/bm500337r

“Abstract: Lipid-coated poly(lactide-co-glycolide) microparticles (LCMPs) consist of a solid polymer core wrapped by a surface lipid bilayer. Previous studies demonstrated that immunization with LCMPs surface-decorated with nanograms of antigen elicit potent humoral immune responses in mice. However, the mechanism of action for these vaccines remained unclear, as LCMPs are too large to drain efficiently to lymph nodes from the vaccination site. Here, we characterized the stability of the lipid envelope of LCMPs and discovered that in the presence of serum the lipid coating of the particles spontaneously delaminates, shedding antigen-displaying vesicles. Lipid delamination generated 180 nm liposomes in a temperature- and lipid/serum-dependent manner. Vesicle shedding was restricted by inclusion of high-TM lipids or cholesterol in the LCMP coating. Administration of LCMPs bearing stabilized lipid envelopes generated weaker antibody responses than those of shedding-competent LCMPs, suggesting that in situ release of antigen-loaded vesicles plays a key role in the remarkable potency of LCMPs as vaccine adjuvants.”

PLGA vaccine

Review Article discusses polymers for drug delivery

PolySciTech (www.polyscitech.com) provides a wide array of biodegradable polymers and block copolymers for drug delivery applications. A recent review article details several of these applications regarding drug delivery. Read more: Behera, Basanta Kumar, Ranjit Mohapatra, and Sunit Kumar Sahoo. “Novel Functionalized Polymers in Drug Delivery: A Brief Review.” Journal of Current Pharma Research 4, no. 3 (2014): 1201-1210. This article is available in full-text here http://www.jcpronline.in/images/articles/1201-1210.pdf

“Abstract: During the last few years, the science and technology of functionalized biodegradable polymers have received considerable interest in the field of polymer chemistry as well as pharmaceuticals. The novel concept behind the approaches is to produce improved polymers with enhanced desirable properties. In the recent years the functionalized polymers are synthesized and used in the form of Polymeric micelle, Polymer vesicles / Polymersomes, Films, Nanocomposite particles, “Smart” polymer conjugates, Hydrogels, Nanogels / Hydrogel nanoparticles, Mesoporous silica nanoparticles, Magnetic nanoparticles (MNPs) and Nanoparticles for improving pharmaceutical properties and therapeutic efficacy of the drugs. The functionalized polymers not only used as carriers but also improves the complications associated with the novel drug delivery formulations like: reduce P-glycoprotein drug efflux function and prevent drug resistance, improves drug loading, improved gene delivery in mesenchymal stem cells etc. In future these functionalized polymers are going to play a vital role in pharmaceutical and biological sciences in order to improve the therapeutic efficacy of a desired drug in field of cancer therapy, tuberculosis therapy, antimicrobial therapy and gene delivery. Keywords: Biodegradable, films, nanoparticles, nanogels, smart polymer conjugates.”

PEG-PLGA copolymer combined with chloroquine for delivery of docetaxel as chemotherapeutic agent

PolySciTech (www.polyscitech.com) provides a wide array of PEG-PLGA copolymers. Recently these types of polymers have been used to develop an anti-cancer micelle which delivers docetaxel to the cancer cells and the delivery is improved by co-administration with chloroquine to reduce cellular lysosome degradation of the micelle. Read more:  Zhang, Xudong, Xiaowei Zeng, Xin Liang, Ying Yang, Xiaoming Li, Hongbo Chen, Laiqiang Huang, Lin Mei, and Si-Shen Feng. “The chemotherapeutic potential of PEG- b-PLGA copolymer micelles that combine chloroquine as autophagy inhibitor and docetaxel as an anti-cancer drug.” Biomaterials (2014). http://www.sciencedirect.com/science/article/pii/S0142961214008370

“Abstract: Micelles may be the nanocarrier that is used most often in the area of nanomedicine due to its promising performance and technical simplicity. However, like the original drugs, micellar formulation may arouse intracellular autophagy that deteriorates their advantages for efficient drug delivery. There has been no report in the literature that involves the fate of micelles after successfully internalized into the cancer cells. In this study, we show by using docetaxel-loaded PEG-b-PLGA micelles as a micellar model that the micelles do arouse intracellular autophagy and are thus subject to degradation through the endo-lysosome pathway. Moreover, we show that co-administration of the micellar formulation with autophagy inhibitor such as chloroquine (CQ) could significantly enhance their therapeutic effects. The docetaxel-loaded PEG-b-PLGA micelles are formulated by the membrane dialysis method, which are of 7.1% drug loading and 72.8% drug encapsulation efficiency in a size range of around 40 nm with narrow size distribution. Autophagy degradation and inhibition are investigated by confocal laser scanning microscopy with various biological makers. We show that the IC50 values of the drug formulated in the PEG-b-PLGA micelles after 24 h treatment MCF-7 cancer cells with no autophagy inhibitor or in combination with CQ were 22.30 ± 1.32 and 1.75 ± 0.43 μg/mL respectively, which indicated a 12-fold more efficient treatment with CQ. The in vivo investigation further confirmed the advantages of such a strategy. The findings may provide advanced knowledge for development of nanomedicine for clinical application. Keywords: Biodegradable polymers; Cancer nanotechnology; Chemotherapeutic engineering; Intracellular autophagy; Nanomedicine; Pharmaceutical nanotechnology”

PLGA and PCL investigated as stem-cell scaffold components for regeneration of human thumb

PolySciTech (www.polyscitech.com) provides a wide array of PLGA and PCL polymers. Recently these types of polymers were investigated as part of a stem-cell loaded scaffold for use in regenerating lost bone materials in thumb or fingers. As part of the study human bone was grown on these scaffolds in mice and tested for its strength and for bone tissue formation. Read more: Weinand, C., E. Weinberg, C. M. Neville, R. Gupta, F. Shapiro, and J. P. Vacanti. “LOP29: Human Stem Cells and Hydrogel β-TCP/PCl versus Hydrogel β-TCP/PLGA Scaffolds in Human Thumb Regeneration.” Plastic and Reconstructive Surgery 134, no. 2 (2014): 389.  http://journals.lww.com/plasreconsurg/Abstract/2014/08000/LOP29___Human_Stem_Cells_and_Hydrogel___TCP_PCl.98.aspx

“Abstract: Introduction: The absence of the thumb from either trauma or congenital defect renders a patient in severe disability and loss of function in daily life. What is the best B-TCP based biomaterial for tissue engineering human thumb bones? Material and Methods: In our experiment, we used three-dimensional printed (3DP) scaffolds from a CT scan of a human distal phalanx to test ability to support bone formation in vivo.  Human mesenchymal stem cells (hMSCs) were expanded, suspended in collagen I and fibrin glue hydrogel and applied onto 3DP B-TCP/PCL or B-TCP/PLGA scaffolds. Acellular constructs and scaffolds only served as controls. Constructs were implanted subcutaneously into nude mice for 6 weeks. Samples were then evaluated using high resolution VCT scanning, histologically by Toluidin blue, van Kossa, and alkaline phosphatase stain and biomechanically. Results: In vivo high resolution VCT scanning revealed densities closer to native bone in cellular B-TCP/PLGA specimens than in B-TCP/PCL specimens. Histologically collagen I hydrogel B-TCP/PLGA specimens had superior bone tissue, although radiopacities were detected in collagen I and Fibrin glue B-TCP/PCL samples. Biomechanical compression testing, however showed higher stiffness in cellular B-TCP/PCL collagen I than in B-TCP/PLGA. Expression of bone specific proteins was highest in cellular B-TCP/PLGA collagen I specimens. Statistical analysis confirmed high correlations between volumetric CT and biomechanical values and expression of bone specific proteins. Conclusion: This new approach could be potentially used in the surgical reconstruction for patients with bone loss of the hand.”

PLGA used as a component in an anti-inflammatory bone scaffold

PolySciTech (www.polyscitech.com) provides a wide array of PLGA polymers and related biodegradable polyesters.  Recently PLGA has been used along with other components to generate a bone scaffold that allows for repairing large defects or substantial fractures.  This scaffold was loaded with an anti-inflammatory drug which were found to aid in the healing process when loaded at the correct dose. Read more: Sidney, Laura E., Thomas RJ Heathman, Emily R. Britchford, Arif Abed, Cheryl V. Rahman, and Lee D. Buttery. “Investigation of localised delivery of diclofenac sodium from PLGA/PEG scaffolds using an in vitro osteoblast inflammation model.” Tissue Engineering ja (2014). http://online.liebertpub.com/doi/abs/10.1089/ten.TEA.2014.0100

“ABSTRACT: Non-union fractures and large bone defects are significant targets for osteochondral tissue engineering strategies. A major hurdle in the use of these therapies is the foreign body response of the host. Herein, we report the development of a bone tissue engineering scaffold with the ability to release anti-inflammatory drugs, in the hope of evading this response. Porous, sintered scaffolds composed of poly(DL-lactic acid-co-glycolic acid) (PLGA) and poly(ethylene glycol) (PEG) were prepared with and without the anti-inflammatory drug diclofenac sodium. Analysis of drug release over time demonstrated a profile suitable for the treatment of acute inflammation with approximately 80% of drug released over the first 4 days and a subsequent release of around 0.2% per day. Effect of drug release was monitored using an in vitro osteoblast inflammation model, comprised of mouse primary calvarial osteoblasts stimulated with proinflammatory cytokines interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and interferon-γ (IFN-γ). Levels of inflammation were monitored by cell viability and cellular production of nitric oxide (NO) and prostaglandin E<sub>2</sub> (PGE<sub>2</sub>). The osteoblast inflammation model revealed that proinflammatory cytokine addition to the medium reduced cell viability to 33%, but the release of diclofenac sodium from scaffolds inhibited this effect with a final cell viability of approximately 70%. However, releasing diclofenac sodium at high concentrations had a toxic effect on the cells. Proinflammatory cytokine addition led to increased NO and PGE<sub>2</sub> production; diclofenac sodium releasing scaffolds inhibited NO release by approximately 64% and PGE<sub>2</sub> production by approximately 52%, when the scaffold was loaded with the optimal concentration of drug. These observations demonstrate the potential use of PLGA/PEG scaffolds for localised delivery of anti-inflammatory drugs in bone tissue engineering applications.”

PLA-PEG-PLA optimized micelle for drug delivery determined by computer simulation and confirmed by laboratory results

PolySciTech (www.polyscitech.com) provides a wide array of biodegradable block copolymers including PLA-PEG-PLA triblock copolymers at a variety of MW’s and chiral characteristics. Recent research utilizing Dissipative Particle Dynamic simulations back by laboratory experimental results have honed in on the optimal PEG to PLA ratio for forming a micelle for drug delivery. Read more: Chansuna, Mantana, and Nuttaporn Pimpha. “Mesoscale simulation and experimental studies of self-assembly behavior of a PLA-PEG-PLA triblock copolymer micelle for sustained drug delivery.” Journal of Polymer Research 21, no. 6 (2014): 1-9. http://link.springer.com/article/10.1007/s10965-014-0452-1

“Abstract: Dissipative Particle Dynamic simulation (DPD) was employed to investigate PLA-PEG-PLA copolymer micelles to gain more understanding at the molecular level in addition to experimental studies. Critical micelle concentration (cmc), micelle size and small molecule encapsulation of these triblock copolymer micelles with different hydrophobic/hydrophilic (LA/EG) block ratios (2.56, 4.88 and 7.25 with fixed PEG length = 23 monomer units) were determined. Only the appropriated LA/EG block ratio (4.88 and 7.25) can induce the formation of spherical micelle in a dilute solution. The cmc and micelle size were decreased and increased, respectively, as a function of the LA/EG block ratio. Upon adding small solubilizate molecules, a larger micelle size was formed. Then, PLA-PEG-PLA with the same LA/EG block ratios as DPD simulation were synthesized and the micelle solution was prepared. Pyrene was used as the molecular probe to find the cmc by fluorescence spectroscopy. Light scattering was applied to determine the hydrodynamic radius (R H ) of these micelles. The cmc and RH were decreased and increased, respectively, with LA/EG ratio, qualitatively similar to the trends as simulation results. The behavior of these copolymer micelles to encapsulate the small solubilizate molecules was also studied by fluorescence technique. The partition coefficients of pyrene between the water phase and the micelle core were increased with a higher LA/EG block ratio similar to results from the simulation. Keywords: Triblock copolymer, Micelle, Mesoscale simulation, Drug delivery”

PolySciTech is you’re fix for a science/engineering problem

PolySciTech (www.polyscitech.com) provides a wide array of traditional biodegradable polyesters (e.g. PLGA, PLA, PCL, PLCL), biodegradable block copolymers (e.g. PEG-PLGA), reactive intermediates (maleimide, NH2, NHS endcapped polymers), Fluorescently conjugated polymers (e.g. PLGA-FITC, PLGA-FKR648), monomers, modified PEG’s, Chitosan’s (Kitopure), and other polymer materials as well as is the USA distributor for DKC bioacts fluorescent dye products.  There are many issues to tackle in science and engineering and PST provides the tools to help deal with these issues. If you haven’t already please check out our reference list here which highlights some of the many ways others have used PolySciTech products in their research. https://akinainc.com/polyscitech/products/polyvivo/referenced_by.phpPolyscitech engineering fix

PLGA used along with stem cells for cartilage repair as potential treatment for joint damage

PolySciTech (www.polyscitech.com) provides a wide variety of biodegradable PLGA polymers. Recent studies have paired PLGA porous sheets along with stem cells and tested these in joints of rabbits. It was found that the combination of PLGA/stem cells improved healing in these joints. Read more: Qi, Yiying, Yi Du, Weixu Li, Xuesong Dai, Tengfei Zhao, and Weiqi Yan. “Cartilage repair using mesenchymal stem cell (MSC) sheet and MSCs-loaded bilayer PLGA scaffold in a rabbit model.” Knee Surgery, Sports Traumatology, Arthroscopy 22, no. 6 (2014): 1424-1433. http://link.springer.com/article/10.1007/s00167-012-2256-3

“Abstract: Purpose: The integration of regenerated cartilage with surrounding native cartilage is a major challenge for the success of cartilage tissue-engineering strategies. The purpose of this study is to investigate whether incorporation of the power of mesenchymal stem cell (MSC) sheet to MSCs-loaded bilayer poly-(lactic-co-glycolic acid) (PLGA) scaffolds can improve the integration and repair of cartilage defects in a rabbit model. Methods: Rabbit bone marrow-derived MSCs were cultured and formed cell sheet. Full-thickness cylindrical osteochondral defects (4 mm in diameter, 3 mm in depth) were created in the patellar groove of 18 New Zealand white rabbits and the osteochondral defects were treated with PLGA scaffold (n = 6), PLGA/MSCs (n = 6) or MSC sheet-encapsulated PLGA/MSCs (n = 6). After 6 and 12 weeks, the integration and tissue response were evaluated histologically. Results: The MSC sheet-encapsulated PLGA/MCSs group showed significantly more amounts of hyaline cartilage and higher histological scores than PLGA/MSCs group and PLGA group (P < 0.05). In addition, the MSC sheet-encapsulated PLGA/MCSs group showed the best integration between the repaired cartilage and surrounding normal cartilage and subchondral bone compared to other two groups. Conclusions: The novel method of incorporation of MSC sheet to PLGA/MCSs could enhance the ability of cartilage regeneration and integration between repair cartilage and the surrounding cartilage. Transplantation of autologous MSC sheet combined with traditional strategies or cartilage debris might provide therapeutic opportunities for improving cartilage regeneration and integration in humans.”