|  |  |  | | | | | TERMSC | | | | | | | | | | | | | | | | | | | Vitamin E triggers poly(2-hydroxyethyl methacrylate) (PHEMA) embolic potential: a proposed application for endovascular surgery. J Biomater Sci Polym Ed. 2011;22(4-6):641-50 Authors: Renò F, Traina V, Gatti S, Cannas M Poly(2-hydroxyethyl methacrylate) (PHEMA) is a biocompatible polymer used as embolizing agent for endovascular surgery. Blending of PHEMA with a hydrophobic and anti-oxidant agent, Vitamin E (Vit.E, 0.1-10%, w/v), modified PHEMA's haemocombatibility, evaluated measuring wettability, plasma protein adsorption along with whole blood coagulation time. The presence of Vit.E increases PHEMA's hydrophobicity and plasma protein adsorption (in particular albumin and Immunoglobulin G), while it also accelerates blood clot formation. These effects are developed due to a combination of issues such as surface hydrophobicity and plasma protein adsorption induced by the presence of Vit.E, suggesting that Vit.E blending could improve the use of PHEMA as embolizing agent. PMID: 20566049 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Highly Extensible, Tough, and Elastomeric Nanocomposite Hydrogels from Poly(ethylene glycol) and Hydroxyapatite Nanoparticles. Biomacromolecules. 2011 Mar 17; Authors: Gaharwar AK, Dammu SA, Canter JM, Wu CJ, Schmidt G Unique combinations of hard and soft components found in biological tissues have inspired researchers to design and develop synthetic nanocomposite gels and hydrogels with elastomeric properties. These elastic materials can potentially be used as synthetic mimics for diverse tissue engineering applications. Here we present a set of elastomeric nanocomposite hydrogels made from poly(ethylene glycol) (PEG) and hydroxyapatite nanoparticles (nHAp). The aqueous nanocomposite PEG-nHAp precursor solutions can be injected and then covalently cross-linked via photopolymerization. The resulting PEG-nHAp hydrogels have interconnected pore sizes ranging from 100 to 300 nm. They have higher extensibilities, fracture stresses, compressive strengths, and toughness when compared with conventional PEO hydrogels. The enhanced mechanical properties are a result of polymer nanoparticle interactions that interfere with the permanent cross-linking of PEG during photopolymerization. The effect of nHAp concentration and temperature on hydrogel swelling kinetics was evaluated under physiological conditions. An increase in nHAp concentration decreased the hydrogel saturated swelling degree. The combination of PEG and nHAp nanoparticles significantly improved the physical and chemical hydrogel properties as well as some biological characteristics such as osteoblast cell adhesion. Further development of these elastomeric materials can potentially lead to use as a matrix for drug delivery and tissue repair especially for orthopedic applications. PMID: 21413708 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cell responses and hemocompatibility of g-HA/PLA composites. Sci China Life Sci. 2011 Mar 17; Authors: Li J, Zheng W, Zheng Y, Lou X The objective of this study was to investigate the hemocompatibility and cell responses to some novel poly(L-lactide) (PLA) composites containing surface modified hydroxyapatite particles for potential applications as a bone substitute material. The surface of hydroxyapatite (HA) particles was first grafted with L-lactic acid oligomers to form grafted HA (g-HA) particles. The g-HA particles were further blended with PLA to prepare g-HA/PLA composites. Our previous study has shown significant improvement in tensile properties of these materials due to the enhanced interfacial adhesion between the polymer matrix and HA particles. To further investigate the potential applications of these composites in bone repair and other orthopedic surgeries, a series of in vitro and in vivo experiments were conducted to examine the cell responses and hemocompatibility of the materials. In vitro experiments showed that the g-HA/PLA composites were well tolerated by the L-929 cells. Hemolysis of the composites was lower than that of pure PLA. Subcutaneous implantation demonstrated that the g-HA/PLA composites were more favorable than the control materials for soft tissue responses. The results suggested that the g-HA/PLA composites are promising and safe materials with potential applications in tissue engineering. PMID: 21416229 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Designing a tubular matrix of oriented collagen fibrils for tissue engineering. Acta Biomater. 2011 Mar 14; Authors: Lai ES, Anderson CM, Fuller GG A scaffold composed entirely of an extracellular matrix component, such as collagen, with cellular level control can be highly desirable for applications in tissue engineering. In this article, we introduce a novel, straightforward flow processing technique that fabricates a small-diameter tubular matrix constructed of anisotropic collagen fibrils. Scanning electron microscopy confirmed the uniformed alignment of the collagen fibrils and subsequent matrix-induced alignment of human fibroblasts. The uniform alignment of the fibroblasts along the collagen fibrils demonstrated the ability of the aligned fibrils to successfully dictate the directional growth of human fibroblasts through contact guidance. Various non-cytotoxic cross-linking techniques were also conducted on the collagen conduit to enhance the conduit's mechanical properties. Tensile testing and burst pressure were the two types of measurements performed to characterize the mechanical integrity of the conduit. The mechanical characterization of the cross-linked collagen conduits identified the 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide hydrochloride cross-linking as the most promising technique to reinforce the native collagen's mechanical properties. An oriented conduit of biocompatible material has been fabricated with decent mechanical strength and at a small-diameter scale, which is especially applicable in engineering cardiovascular tissues and nerve grafts. PMID: 21414424 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Small hairpin RNA interference of the Nogo receptor inhibits oxygen-glucose deprivation-induced damage in rat hippocampal slice cultures. Neuropathology. 2010 Dec;30(6):565-73 Authors: Peng Y, Zhang QL, Xu D, Wang YP, Qin XY In adult mammals, CNS damage does not repair well spontaneously. The Nogo receptor (NgR) signaling pathway prevents axonal regrowth and promotes neuronal apoptosis. This pathway, and pathways like it, may be part of the reason why nerves do not regrow. A number of preclinical experiments inhibiting portions of the NgR pathway have yielded limited induction of nerve repair. Here, we developed a small hairpin RNA (shRNA) to knock down NgR expression. With the use of rat hippocampal slices in tissue culture, we induced neuronal damage similar to that of ischemia-reperfusion injury by exposing the cultured tissues to oxygen-glucose deprivation. We then assayed the effect of NgR knockdown in this model system. Adenovirally delivered NgR shRNA decreased NgR mRNA and protein expression. Thirty minutes of oxygen-glucose deprivation resulted in widespread tissue damage, including apoptosis and loss of neurite extension, 72 h after termination of oxygen-glucose deprivation. The NgR shRNA knockdown reduced, but did not eliminate, the effects of oxygen-glucose deprivation. Thus, NgR shRNA shows promise as a potential tool for the treatment of nerve damage. PMID: 20337950 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Influence of PDGF-AB on Tissue Development in Autologous Platelet-Rich Plasma Gels. Tissue Eng Part A. 2011 Mar 17; Authors: Wirz S, Dietrich M, Flanagan TC, Bokermann G, Wagner W, Schmitz-Rode T, Jockenhoevel S Fibrin-based scaffolds are widely used in tissue engineering. We postulated that the use of platelet-rich plasma (PRP) in contrast to platelet-poor plasma (PPP) and pure fibrinogen as the basic material leads to an increased release of autologous PDGF-AB (platelet-derived growth factor), which may have a consequent positive effect on tissue development. Therefore, we evaluated the release of PDGF-AB during the production process and the course of PDGF release during cultivation of plasma gels with and w/o platelets. The influence of PDGF-AB on the proliferation rate of human umbilical cord artery smooth muscle cells (HUASMCs) was studied using XTT assay. The synthesis of extracellular matrix (ECM) by HUASMCs in plasma- and fibrin gels was measured using hydroxyproline assay. The use of PRP led to an increase in autologous PDGF-AB release. Furthermore, the platelet-containing plasma gels showed a prolonged release of growth factor during cultivation. Both PRP and PPP gels had a positive effect on the production of collagen. However, PDGF-AB as a supplement in medium and in pure fibrin gel had neither an effect on cell proliferation nor on the collagen synthesis rate. This observation may be due to an absence of PDGF receptors in HUASMCs as determined by flow cytometry. In conclusion, although the prolonged autologous production of PDGF-AB in PRP gels is possible, the enhanced tissue development by HUASMCs within such gels is not PDGF-related. PMID: 21413900 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Nanobiotechnologies in medicine: nanodiagnostics and nanodrugs]. Biomed Khim. 2010 Jan-Feb;56(1):7-25 Authors: Archakov AI PMID: 21328908 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Multilayered Microspheres for the Controlled Release of Growth Factors in Tissue Engineering. Biomacromolecules. 2011 Mar 17; Authors: Go DP, Gras SL, Mitra D, Nguyen TH, Stevens GW, Cooper-White JJ, O'Connor AJ Tissue regeneration may be stimulated by growth factors but to be effective, this delivery must be sustained and requires delivery vehicles that overcome the short half-life of these molecules in vivo. One promising approach is to couple growth factors to the biomaterial surface so that they are readily bioavailable. Here the layer-by-layer process was used to construct a multilayered polyelectrolyte delivery system on the surface of poly(lactic-co-glycolic) acid constructs. The system was first optimized on a planar surface before translation to a 3D microsphere system. The layers incorporated heparin to facilitate the loading of basic fibroblast growth factor and increase growth factor stability. Cross-linked capping layers also reduced any burst release. The model growth factor was released in a sustained manner and stimulated significantly higher cell proliferation in vitro on release compared with the addition of the growth factor heparin complex free in solution, demonstrating the promise of this approach. PMID: 21413682 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | |  | |  | |  |
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