|  |  |  | | | | | TERMSC | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Systems biology and inflammation. Methods Mol Biol. 2010;662:181-201 Authors: Vodovotz Y, An G Inflammation is a complex, multiscale biological response to threats - both internal and external - to the body, which is also required for proper healing of injured tissue. In turn, damaged or dysfunctional tissue stimulates further inflammation. Despite continued advances in characterizing the cellular and molecular processes involved in the interactions between inflammation and tissue damage, there exists a significant gap between the knowledge of mechanistic pathophysiology and the development of effective therapies for various inflammatory conditions. We have suggested the concept of translational systems biology, defined as a focused application of computational modeling and engineering principles to pathophysiology primarily in order to revise clinical practice. This chapter reviews the existing, translational applications of computational simulations and related approaches as applied to inflammation. PMID: 20824472 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Differential Trafficking of Oxidized LDL and Oxidized LDL Immune Complexes in Macrophages: Impact on Oxidative Stress. PLoS One. 2010;5(9): Authors: Al Gadban MM, Smith KJ, Soodavar F, Piansay C, Chassereau C, Twal WO, Klein RL, Virella G, Lopes-Virella MF, Hammad SM BACKGROUND: Oxidized low-density lipoproteins (oxLDL) and oxLDL-containing immune complexes (oxLDL-IC) contribute to formation of lipid-laden macrophages (foam cells). It has been shown that oxLDL-IC are considerably more efficient than oxLDL in induction of foam cell formation, inflammatory cytokines secretion, and cell survival promotion. Whereas oxLDL is taken up by several scavenger receptors, oxLDL-IC are predominantly internalized through the FCgamma receptor I (FCgamma RI). This study examined differences in intracellular trafficking of lipid and apolipoprotein moieties of oxLDL and oxLDL-IC and the impact on oxidative stress. METHODOLOGY/FINDINGS: Fluorescently labeled lipid and protein moieties of oxLDL co-localized within endosomal and lysosomal compartments in U937 human monocytic cells. In contrast, the lipid moiety of oxLDL-IC was detected in the endosomal compartment, whereas its apolipoprotein moiety advanced to the lysosomal compartment. Cells treated with oxLDL-IC prior to oxLDL demonstrated co-localization of internalized lipid moieties from both oxLDL and oxLDL-IC in the endosomal compartment. This sequential treatment likely inhibited oxLDL lipid moieties from trafficking to the lysosomal compartment. In RAW 264.7 macrophages, oxLDL-IC but not oxLDL induced GFP-tagged heat shock protein 70 (HSP70) and HSP70B', which co-localized with the lipid moiety of oxLDL-IC in the endosomal compartment. This suggests that HSP70 family members might prevent the degradation of the internalized lipid moiety of oxLDL-IC by delaying its advancement to the lysosome. The data also showed that mitochondrial membrane potential was decreased and generation of reactive oxygen and nitrogen species was increased in U937 cell treated with oxLDL compared to oxLDL-IC. CONCLUSIONS/SIGNIFICANCE: Findings suggest that lipid and apolipoprotein moieties of oxLDL-IC traffic to separate cellular compartments, and that HSP70/70B' might sequester the lipid moiety of oxLDL-IC in the endosomal compartment. This mechanism could ultimately influence macrophage function and survival. Furthermore, oxLDL-IC might regulate the intracellular trafficking of free oxLDL possibly through the induction of HSP70/70B'. PMID: 20824093 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | An interview with Ken Zaret. Development. 2010 Oct;137(19):3151-2 Authors: Senior K Ken Zaret is Joseph Leidy Professor in the Department of Cell and Developmental Biology, the Associate Director of the Institute for Regenerative Medicine, and the Co-Director of the Epigenetics Program at the University of Pennsylvania School of Medicine. He agreed to be interviewed by Development and talks about his life as a scientist. PMID: 20823060 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Aggregation of human mesenchymal stromal cells (MSCs) into 3D spheroids enhances their antiinflammatory properties. Proc Natl Acad Sci U S A. 2010 Aug 3;107(31):13724-9 Authors: Bartosh TJ, Ylöstalo JH, Mohammadipoor A, Bazhanov N, Coble K, Claypool K, Lee RH, Choi H, Prockop DJ Previous reports suggested that culture as 3D aggregates or as spheroids can increase the therapeutic potential of the adult stem/progenitor cells referred to as mesenchymal stem cells or multipotent mesenchymal stromal cells (MSCs). Here we used a hanging drop protocol to prepare human MSCs (hMSCs) as spheroids that maximally expressed TNFalpha stimulated gene/protein 6 (TSG-6), the antiinflammatory protein that was expressed at high levels by hMSCs trapped in the lung after i.v. infusion and that largely explained the beneficial effects of hMSCs in mice with myocardial infarcts. The properties of spheroid hMSCs were found to depend critically on the culture conditions. Under optimal conditions for expression of TSG-6, the hMSCs also expressed high levels of stanniocalcin-1, a protein with both antiinflammatory and antiapoptotic properties. In addition, they expressed high levels of three anticancer proteins: IL-24, TNFalpha-related apoptosis inducing ligand, and CD82. The spheroid hMSCs were more effective than hMSCs from adherent monolayer cultures in suppressing inflammatory responses in a coculture system with LPS-activated macrophages and in a mouse model for peritonitis. In addition, the spheroid hMSCs were about one-fourth the volume of hMSCs from adherent cultures. Apparently as a result, larger numbers of the cells trafficked through the lung after i.v. infusion and were recovered in spleen, liver, kidney, and heart. The data suggest that spheroid hMSCs may be more effective than hMSCs from adherent cultures in therapies for diseases characterized by sterile tissue injury and unresolved inflammation and for some cancers that are sensitive to antiinflammatory agents. PMID: 20643923 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Induction of complete and molecular remissions in acute myeloid leukemia by Wilms' tumor 1 antigen-targeted dendritic cell vaccination. Proc Natl Acad Sci U S A. 2010 Aug 3;107(31):13824-9 Authors: Van Tendeloo VF, Van de Velde A, Van Driessche A, Cools N, Anguille S, Ladell K, Gostick E, Vermeulen K, Pieters K, Nijs G, Stein B, Smits EL, Schroyens WA, Gadisseur AP, Vrelust I, Jorens PG, Goossens H, de Vries IJ, Price DA, Oji Y, Oka Y, Sugiyama H, Berneman ZN Active immunization using tumor antigen-loaded dendritic cells holds promise for the adjuvant treatment of cancer to eradicate or control residual disease, but so far, most dendritic cell trials have been performed in end-stage cancer patients with high tumor loads. Here, in a phase I/II trial, we investigated the effect of autologous dendritic cell vaccination in 10 patients with acute myeloid leukemia (AML). The Wilms' tumor 1 protein (WT1), a nearly universal tumor antigen, was chosen as an immunotherapeutic target because of its established role in leukemogenesis and superior immunogenic characteristics. Two patients in partial remission after chemotherapy were brought into complete remission after intradermal administration of full-length WT1 mRNA-electroporated dendritic cells. In these two patients and three other patients who were in complete remission, the AML-associated tumor marker returned to normal after dendritic cell vaccination, compatible with the induction of molecular remission. Clinical responses were correlated with vaccine-associated increases in WT1-specific CD8+ T cell frequencies, as detected by peptide/HLA-A*0201 tetramer staining, and elevated levels of activated natural killer cells postvaccination. Furthermore, vaccinated patients showed increased levels of WT1-specific IFN-gamma-producing CD8+ T cells and features of general immune activation. These data support the further development of vaccination with WT1 mRNA-loaded dendritic cells as a postremission treatment to prevent full relapse in AML patients. PMID: 20631300 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Human RASSF7 regulates the microtubule cytoskeleton and is required for spindle formation, Aurora B activation and chromosomal congression during mitosis. Biochem J. 2010 Aug 13;430(2):207-13 Authors: Recino A, Sherwood V, Flaxman A, Cooper WN, Latif F, Ward A, Chalmers AD RASSF7, a member of the N-terminal Ras association domain family, has increased expression in various cancers and, on the basis of our previous work in Xenopus embryos, may be a regulator of mitosis. In the present study, we address, for the first time, the role of human RASSF7 in mitosis. We demonstrate that RASSF7 is expressed in a broad range of different cell types and that this expression could be enhanced following exposure to hypoxia. Knocking down RASSF7 in human cell lines inhibited cell growth and induced defects in mitosis, including aberrant spindle formation and a failure in chromosomal congression. In order to understand the molecular basis of the defects in more detail, we analysed the activity of mitotic signalling proteins and found that activation of Aurora B did not occur in cells in which RASSF7 was knocked down. We also show that endogenous RASSF7 protein localizes to the centrosome and demonstrate using microtubule-regrowth assays that RASSF7 is an important regulator of microtubule dynamics. On the basis of these observations, we propose that, owing to its key role in regulating the microtubule cytoskeleton, RASSF7 is required for mitosis in human cells. PMID: 20629633 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | MicroRNA miR-125a controls hematopoietic stem cell number. Proc Natl Acad Sci U S A. 2010 Aug 10;107(32):14229-34 Authors: Guo S, Lu J, Schlanger R, Zhang H, Wang JY, Fox MC, Purton LE, Fleming HH, Cobb B, Merkenschlager M, Golub TR, Scadden DT MicroRNAs influence hematopoietic differentiation, but little is known about their effects on the stem cell state. Here, we report that the microRNA processing enzyme Dicer is essential for stem cell persistence in vivo and a specific microRNA, miR-125a, controls the size of the stem cell population by regulating hematopoietic stem/progenitor cell (HSPC) apoptosis. Conditional deletion of Dicer revealed an absolute dependence for the multipotent HSPC population in a cell-autonomous manner, with increased HSPC apoptosis in mutant animals. An evolutionarily conserved microRNA cluster containing miR-99b, let-7e, and miR-125a was preferentially expressed in long-term hematopoietic stem cells. MicroRNA miR-125a alone was capable of increasing the number of hematopoietic stem cells in vivo by more than 8-fold. This result was accomplished through a differentiation stage-specific reduction of apoptosis in immature hematopoietic progenitors, possibly through targeting multiple proapoptotic genes. Bak1 was directly down-regulated by miR-125a and expression of a 3'UTR-less Bak1 blocked miR-125a-induced hematopoietic expansion in vivo. These data demonstrate cell-state-specific regulation by microRNA and identify a unique microRNA functioning to regulate the stem cell pool size. PMID: 20616003 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Immunity to stemness genes in human cancer. Curr Opin Immunol. 2010 Apr;22(2):245-50 Authors: Dhodapkar MV A growing body of data points to not only intraclonal heterogeneity and hierarchy of growth potential, but also plasticity of cellular differentiation within human tumors. Recent studies have also identified surprising overlap between pathways that regulate pluripotency in embryonal stem (ES) cells and oncogenesis. While there is a long history of targeting embryonal tissues toward cancer vaccines, recent identification of crucial stemness pathways in ES cells as well as putative cancer stem cells (CSCs) provides novel opportunities for antigen-specific targeted therapy. Here we discuss recent insights into the capacity of the immune system to target these pathways. Immunologic targeting of pathways associated with stemness has implications for both immune regulation of tumor growth as well as regenerative therapies with embryonal stem cells. PMID: 20144857 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Functionalization of Silk Fibroin with NeutrAvidin and Biotin. Macromol Biosci. 2010 Sep 7; Authors: Wang X, Kaplan DL New methods are needed to modify silk biomaterials with bioactive molecules for tissue engineering and drug delivery. In the present study, silk fibroin in solution or in microsphere format was coupled with NeutrAvidin via carbodiimide chemistry. Silk fibroin retained its self-assembly features after reaction. It was found that more than four NeutrAvidin molecules bound to one silk molecule. Non-specific binding of biotin or NeutrAvidin to silk microspheres could be reduced by pre-treatment of the microspheres with BSA or post-treatment with detergent. The NeutrAvidin-coupled silk microspheres were coupled with biotinylated anti-CD3 antibody and the functionalized microspheres were able to specifically bind to the CD3 positive T-lymphocytic cell line Jurkat. PMID: 20824692 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Genipin-crosslinked silk fibroin/hydroxybutyl chitosan nanofibrous scaffolds for tissue-engineering application. J Biomed Mater Res A. 2010 Sep 7; Authors: Zhang K, Qian Y, Wang H, Fan L, Huang C, Yin A, Mo X To improve water-resistant ability and mechanical properties of silk fibroin (SF)/hydroxybutyl chitosan (HBC) nanofibrous scaffolds for tissue-engineering applications, genipin, glutaraldehyde (GTA), and ethanol were used to crosslink electrospun nanofibers, respectively. The mechanical properties of nanofibrous scaffolds were obviously improved after 24 h of crosslinking with genipin and were superior to those crosslinked with GTA and ethanol for 24 h. SEM indicated that crosslinked nanofibers with genipin and GTA vapor had good water-resistant ability. Characterization of the microstructure (porosity and pore structure) demonstrated crosslinked nanofibrous scaffolds with genipin and GTA vapor had lager porosities and mean diameters than those with ethanol. Characterization of FTIR-ATR and (13)C NMR clarified both genipin and GTA acted as crosslinking agents for SF and HBC. Furthermore, genipin could induce SF conformation from random coil or alpha-helix to beta-sheet. Although GTA could also successfully crosslink SF/HBC nanofibrous scaffolds, in long run, genipin maybe a better method due to lower cytotoxicity than GTA. Cell viability studies and wound-healing test in rats clarified that the genipin-crosslinked SF/HBC nanofibrous scaffolds had a good biocompatibility both in vitro and in vivo. These results suggested that genipin-crosslinked SF/HBC nanofibrous scaffolds might be potential candidates for wound dressing and tissue-engineering scaffolds. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20824649 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human pathogens, nosocomial infections, heat-sensitive textile implants, and an innovative approach to deal with them. J Ind Microbiol Biotechnol. 2010 Sep 8; Authors: Cinquemani C Implantable polymers, as used for biomedical applications, inherently have to be sterile. Nonetheless, most implants, particularly those comprised of biomaterials developed in recent years for tissue engineering, are heat sensitive. Therefore, use of hazardous (radio)chemicals-due to lack of alternative methods-is still state of the art for sterilization processes. The drawbacks of these techniques, both drastic and well known, lead to the demand for an alternative sterilization method, which is equally obvious and urgent. High-pressure fluid treatment is a low-temperature technique that is already in use for pasteurization of liquid food products. This paper explores inactivation of vegetative microorganisms, spores, and endotoxins adherent to solid surfaces using compressed CO(2). Pressures ranging from 50 to 100 bar and temperatures from 25 degrees C to 50 degrees C were explored to investigate liquid, gaseous or supercritical state. Analysis of variance (ANOVA) and statistical modeling were used to identify the optimum parameter settings for inactivation of pathogenic bacteria and fungi (Candida albicans, Staphylococcus aureus). The addition of small amounts of ozone ensures inactivation of persistent spores (Bacillus stearothermophilus, B. subtilis) up to 10(6) cfu/ml, while endotoxins remain in practically unchanged concentration on the polymer surface. We then discuss environmental issues of the process and inactivation mechanisms. The replacement of conventional chemicals with nonpersistent ones resolves organizational and safety-related issues and protects natural resources as well as handling staff. The pressurized-fluid-based method exhibits mild treatment parameters, thus protecting sensitive textures. Finally, an outlook on possible applications of this innovative technique is presented. PMID: 20824488 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human lung tissue engineering: a critical tool for safer medicines. Cell Tissue Bank. 2010 Sep 8; Authors: Bérubé K, Gibson C, Job C, Prytherch Z In the field of human tissue-engineering, there has been a strong focus on the clinical aspects of the technology, i.e. repair, replace and enhance a given tissue/organ. However, much wider applications for tissue engineering (TE) exist outside of the clinic that are often not recognised, and include engineering more relevant models than animals in basic research and safety testing. Traditionally, research is initially conducted on animals or cell lines, both of which have their limitations. With regard to cell lines, they are usually transformed to enable indefinite proliferation. These immortalised cell lines provide the researcher with an almost limitless source of material. However, the pertinence of the data produced is now under scrutiny, with the suggestion that some historical cell lines may not be the cell type originally reported. By engineering normal, biomimetic (i.e. life-mimicking), human tissues with defined physiology (i.e. human tissue equivalents), the complex 3-dimensional (3-D) tissue/organ physiology is captured in vitro, providing the opportunity to directly replace the use of animals in research/testing with more relevant systems. Therefore, it is imperative that testing strategies using organotypic models are developed that can address the limitations of current animal and cellular models and thus improve drug development, enabling faster delivery of drugs which are safer, more effective and have fewer side effects in humans. PMID: 20824355 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Additive manufacturing for in situ repair of osteochondral defects. Biofabrication. 2010 Sep;2(3):035004 Authors: Cohen DL, Lipton JI, Bonassar LJ, Lipson H Tissue engineering holds great promise for injury repair and replacement of defective body parts. While a number of techniques exist for creating living biological constructs in vitro, none have been demonstrated for in situ repair. Using novel geometric feedback-based approaches and through development of appropriate printing-material combinations, we demonstrate the in situ repair of both chondral and osteochondral defects that mimic naturally occurring pathologies. A calf femur was mounted in a custom jig and held within a robocasting-based additive manufacturing (AM) system. Two defects were induced: one a cartilage-only representation of a grade IV chondral lesion and the other a two-material bone and cartilage fracture of the femoral condyle. Alginate hydrogel was used for the repair of cartilage; a novel formulation of demineralized bone matrix was used for bone repair. Repair prints for both defects had mean surface errors less than 0.1 mm. For the chondral defect, 42.8 +/- 2.6% of the surface points had errors that were within a clinically acceptable error range; however, with 1 mm path planning shift, an estimated approximately 75% of surface points could likely fall within the benchmark envelope. For the osteochondral defect, 83.6 +/- 2.7% of surface points had errors that were within clinically acceptable limits. In addition to implications for minimally invasive AM-based clinical treatments, these proof-of-concept prints are some of the only in situ demonstrations to-date, wherein the substrate geometry was unknown a priori. The work presented herein demonstrates in situ AM, suggests potential biomedical applications and also explores in situ-specific issues, including geometric feedback, material selection and novel path planning techniques. PMID: 20823507 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication of three-dimensional porous cell-laden hydrogel for tissue engineering. Biofabrication. 2010 Sep;2(3):035003 Authors: Hwang CM, Sant S, Masaeli M, Kachouie NN, Zamanian B, Lee SH, Khademhosseini A For tissue engineering applications, scaffolds should be porous to enable rapid nutrient and oxygen transfer while providing a three-dimensional (3D) microenvironment for the encapsulated cells. This dual characteristic can be achieved by fabrication of porous hydrogels that contain encapsulated cells. In this work, we developed a simple method that allows cell encapsulation and pore generation inside alginate hydrogels simultaneously. Gelatin beads of 150-300 microm diameter were used as a sacrificial porogen for generating pores within cell-laden hydrogels. Gelation of gelatin at low temperature (4 degrees C) was used to form beads without chemical crosslinking and their subsequent dissolution after cell encapsulation led to generation of pores within cell-laden hydrogels. The pore size and porosity of the scaffolds were controlled by the gelatin bead size and their volume ratio, respectively. Fabricated hydrogels were characterized for their internal microarchitecture, mechanical properties and permeability. Hydrogels exhibited a high degree of porosity with increasing gelatin bead content in contrast to nonporous alginate hydrogel. Furthermore, permeability increased by two to three orders while compressive modulus decreased with increasing porosity of the scaffolds. Application of these scaffolds for tissue engineering was tested by encapsulation of hepatocarcinoma cell line (HepG2). All the scaffolds showed similar cell viability; however, cell proliferation was enhanced under porous conditions. Furthermore, porous alginate hydrogels resulted in formation of larger spheroids and higher albumin secretion compared to nonporous conditions. These data suggest that porous alginate hydrogels may have provided a better environment for cell proliferation and albumin production. This may be due to the enhanced mass transfer of nutrients, oxygen and waste removal, which is potentially beneficial for tissue engineering and regenerative medicine applications. PMID: 20823504 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Consistent Osteoblastic Differentiation of Human Mesenchymal Stem Cells with Bone Morphogenetic Protein 4 and Low Serum. Tissue Eng Part C Methods. 2010 Sep 8; Authors: Cordonnier T, Langonne A, Sohier J, Layrolle P, Rosset P, Sensebe L, Deschaseaux F Providing fully mature and functional osteoblasts is challenging for bone tissue engineering and regenerative medicine. Such cells could be obtained from multipotent bone-marrow mesenchymal stem cells (MSCs) after induction by different osteogenic factors. However, there are some discrepancies in results, notably due to the use of sera and to the type of osteogenic factor. In this study, we compared the osteogenic differentiation of MSCs induced by dexamethasone (Dex) or bone morphogenetic proteins (BMPs) by assessing phenotypes in vitro and functional osteoblasts in vivo. Reducing the content of fetal calf serum from 10% to 2% significantly increased the mineral deposition and expression of osteoblastic markers during osteogenesis. In comparison to Dex condition, the addition of BMP4 greatly improved the differentiation of MSCs into fully mature osteoblasts as seen by the high expression of Osterix. These results were confirmed in different supportive matrixes, plastic flasks or biphasic calcium phosphate biomaterials. In contrast to Dex-derived osteoblasts, BMP4-derived osteoblasts from MSCs were significantly able to produce new bone in subcutis of nude mice in accordance with in vitro results. In conclusion, we describe a convenient ex vivo method to produce consistently mature functional osteoblasts from human MSCs with use of BMP4 and low serum. PMID: 20822481 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | INCREASED MIXING IMPROVES HYDROGEL HOMOGENEITY AND QUALITY OF 3D PRINTED CONSTRUCTS. Tissue Eng Part C Methods. 2010 Sep 8; Authors: Cohen D, Lo W, Tsavaris A, Peng D, Lipson H, Bonassar LJ As the tissue engineering and drug delivery communities place greater emphasis on producing constructs of prescribed geometry and organization, 3D printing is becoming as an increasingly important technique. While numerous tissue printing techniques have emerged, little has been done to characterize the properties of printing inks and the resultant effects on geometric fidelity, cell viability and mechanical integrity. These questions have been neglected largely because of the lack of methods to characterize the real-time properties of printing inks. We present a novel technique for characterizing the homogeneity of hydrogel tissue printing inks that measures loads during ink deposition and its temporal variation, called, "mechanical noise." We then used this technique to determine the effects of increased mixing on the homogeneity of alginate hydrogels and determined whether this results in improved geometric fidelity of printed constructs. We also studied potential adverse effects on cell viability and mechanical integrity of printed parts. Increased mixing between alginate and crosslinker to 128 cycles yielded an 82% reduction in mechanical noise. Geometric fidelity also improved with this increased mixing, in terms of a smoother surface texture, better matching of the target geometry, and fewer point defects. Viability was not adversely affected by increased mixing, and it actually improved by 34% with a 45 minute curing time. As mixing prior to printing was increased from 8 to 200 cycles, the modulus also increased by 110% from 4.0+/-0.1 kPa to 8.4+/-1.0 kPa. The results presented herein motivate a radical shift in alginate printing protocol, and also propose a useful methodology for characterizing 3D printing materials. PMID: 20822480 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Distinct Cell Responses to Substrates Consisting of Poly(epsilon-caprolactone) and Poly(propylene fumarate) in the Presence or Absence of Cross-Links. Biomacromolecules. 2010 Sep 7; Authors: Wang K, Cai L, Hao F, Xu X, Cui M, Wang S To investigate the role of chemical cross-links in regulating biomaterial properties and cell behavior, we have prepared and characterized a series of biodegradable polymer blends in both un-cross-linked and photo-cross-linked forms. In this comparative study, these blends consisted of an oligomeric, cross-linkable, amorphous poly(propylene fumarate) (PPF) and a high-molecular-weight, semicrystalline poly(epsilon-caprolactone) (PCL). After cross-linking, semi-interpenetrating polymer networks (semi-IPNs) were formed by combining PPF chemical network and PCL physical network that was associated by the crystallites. The material design strategy presented here was different from previously studied semicrystalline polymer networks, in which crystallizable segments participated covalently in the chemical network and were significantly suppressed by the network. For these PPF/PCL blends, thermal properties such as melting temperature (T(m)) and crystallinity have been correlated with their rheological and mechanical properties to demonstrate the effects of cross-linking density and crystallinity. Surface morphology, hydrophilicity, and the capability of adsorbing proteins from cell culture media have also been determined. For potential applications in bone and vascular tissue engineering and demonstration of regulating cell behavior on polymer substrates with controllable physicochemical characteristics, in vitro cell studies that included cell viability, attachment, spreading, and proliferation have been performed using mouse MC3T3 cells and primary rat aortic smooth muscle cells (SMCs). In a similar manner, these two cell types have been found to show distinct cell responses to the polymer substrates in the presence or absence of cross-links. PMID: 20822174 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The nanoscale properties of bacterial inclusion bodies and their effect on mammalian cell proliferation. Biomaterials. 2010 Aug;31(22):5805-12 Authors: DÃez-Gil C, Krabbenborg S, GarcÃa-Fruitós E, Vazquez E, RodrÃguez-Carmona E, Ratera I, Ventosa N, Seras-Franzoso J, Cano-Garrido O, Ferrer-Miralles N, Villaverde A, Veciana J The chemical and mechanical properties of bacterial inclusion bodies, produced in different Escherichia coli genetic backgrounds, have been characterized at the nanoscale level. In regard to wild type, DnaK(-) and ClpA(-) strains produce inclusion bodies with distinguishable wettability, stiffness and stiffness distribution within the proteinaceous particle. Furthermore it was possible to observe how cultured mammalian cells respond differentially to inclusion body variants when used as particulate materials to engineer the nanoscale topography, proving that the actual range of referred mechanical properties is sensed and discriminated by biological systems. The data provide evidence of the mechanistic activity of the cellular quality control network and the regulation of the stereospecific packaging of partially folded protein species in bacteria. This inclusion body nanoscale profiling offers possibilities for their fine genetic tuning and the resulting macroscopic effects when applied in biological interfaces. PMID: 20452667 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Gingival mucosa regeneration in athymic mice using in vitro engineered human oral mucosa. Biomaterials. 2010 Aug;31(22):5798-804 Authors: Rouabhia M, Allaire P Our goal was to investigate in vivo tissue formation following the grafting of engineered human oral mucosa to demonstrate its usefulness in replacing mucosal defects in the oral cavity. Human gingival cells were isolated from the oral mucosa and were used in combination with a collagen scaffold to engineer oral mucosa. Structural and ultrastructural analyses revealed that the engineered mucosa had a well-organized stratified epithelium on the surface of the fibroblast-populated lamina propria tissue. Following grafting for 15 and 60 days, the engineered oral mucosa was shown to cover the recipient site with no wound contraction. The regenerated mucosa displayed an epithelium with multiple layers, including a stratum corneum where epithelial cells expressed cytokeratin Ki-67 and K-14 positive cells located in the basal and supra-basal layers. The interaction between the epithelium and the lamina propria was promoted by the formation of a basement membrane structure containing key proteins, such as laminin-5 and type IV collagen. Following the engineered mucosa grafting, the regenerated tissue was well vascularized, similar to the native mucosa. These data demonstrate the usefulness of engineered human oral mucosa as an alternative treatment for mucosal defects in the oral cavity. PMID: 20434214 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Intervertebral disc regeneration after implantation of a cell-free bioresorbable implant in a rabbit disc degeneration model. Biomaterials. 2010 Aug;31(22):5836-41 Authors: Endres M, Abbushi A, Thomale UW, Cabraja M, Kroppenstedt SN, Morawietz L, Casalis PA, Zenclussen ML, Lemke AJ, Horn P, Kaps C, Woiciechowsky C Degeneration of the intervertebral disc is the most common cause of lower back pain. Interestingly, all available treatments are limited to treat the symptoms and not the underlying biologic alterations of the disc. Freeze-dried resorbable non-woven polyglycolic acid (PGA) - hyaluronan implants were used in a degenerated disc disease (DDD) model in New Zealand white rabbits. The constructs were immersed in allogenic serum and implanted into the disc defect. Animals with discectomy only served as controls. The T2-weighted/fat suppression sequence signal intensity of the operated discs as assessed by magnet resonance imaging decreased in both groups one week after the operation compared to a healthy disc. After 12 months the implanted group showed an increase of 51% in the signal intensity compared to the 1-week results whereas the signal intensity in the sham group remained on the same level from one week to 12 months. Histological and quantitative immunohistochemical examination after 12 months indicated cell migration into the defect and showed formation of disc repair tissue. In controls, repair tissue containing type II collagen was not evident. In conclusion, the implantation of polymer-based constructs after discectomy induces tissue regeneration resulting in improvement of the disc water content. PMID: 20430435 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Controlling dispersion of axonal regeneration using a multichannel collagen nerve conduit. Biomaterials. 2010 Aug;31(22):5789-97 Authors: Yao L, de Ruiter GC, Wang H, Knight AM, Spinner RJ, Yaszemski MJ, Windebank AJ, Pandit A Single channel conduits are used clinically in nerve repair as an alternative to the autologous nerve graft. Axons regenerating across single channel tubes, however, may disperse resulting in inappropriate target reinnervation. This dispersion may be limited by multichannel nerve conduits as they resemble the structure of nerve multiple basal lamina tubes. In this study, we investigated the influence of channel number on the axonal regeneration using a series of 1-, 2-, 4-, and 7-channel collagen conduits and commercial (NeuraGen) single channel conduits. Nerve conduits were implanted in rats with a 1 cm gap of sciatic nerve. After four months, quantitative results of regeneration were evaluated with nerve morphometry and the accuracy of regeneration was assessed using retrograde tracing: two tracers being applied simultaneously to tibial and peroneal nerves to determine the percentage of motor neurons with double projections. Recovery of function was investigated with compound muscle action potential recordings and ankle motion analysis. We showed that the fabricated 1-channel and 4-channel conduits are superior to other types of conduits in axonal regeneration. Simultaneous tracing showed a significantly lower percentage of motor neurons with double projections after 2- and 4-channel compared with 1-channel conduit repair. This study shows the potential influence of multichannel guidance on limiting dispersion without decreasing quantitative results of regeneration. PMID: 20430432 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
No comments:
Post a Comment