|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Cardiac stem cells differentiate into sinus node-like cells. Tohoku J Exp Med. 2010;222(2):113-20 Authors: Zhang J, Huang C, Wu P, Yang J, Song T, Chen Y, Fan X, Wang T The advent of stem cell therapy brings about the hope to restore the loss of cardiac pacemaker cells. However, it is largely unknown whether cardiac stem cells are able to differentiate into pacemaker cells. The purpose of this study was to determine whether the heart of large juvenile mammals contains cardiac stem cells (CSCs), which are suitable as seed cells for restoration of cardiac pacemaker cell. The c-kit(+) CSCs were isolated from one-month-old mongrel dogs. CSCs that we sorted were self-renewing, and they could proliferate by clonal expansion. CSCs could differentiate into cardiac muscle, smooth muscle and endothelial cells at rates of 10.5 ± 4.2%, 13.5 ± 5.1% and 12.9 ± 3.5%, respectively, at week 4, as judged by the expression of respective differentiation markers: cardiac troponin I, smooth muscle actin, and CD31. At week 8, the differentiation rates were further increased to 23.2 ± 3.6%, 25.9 ± 6.6% and 28.3 ± 6.1% (P < 0.05 for each marker). Some of cells derived from CSCs could express cardiac transcription factor GATA-4 after week 2 and express pacing-related genes, including hyperpolarization-activated cyclic nucleotide-gated 2 (HCN2) and HCN4 after week 4. Importantly, a fraction of CSCs demonstrated the presence of inward currents that indicate the expression of inward current channels. In conclusion, c-kit(+) CSCs may differentiate into cardiac muscle cell and sinus node-like cells, suggesting that CSCs would be useful as seed cells in treating sinus bradycardiac disorders or exploring the mechanism of pacemaker activity. PMID: 20877167 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The use of biodegradable PLGA nanoparticles to mediate SOX9 gene delivery in human mesenchymal stem cells (hMSCs) and induce chondrogenesis. Biomaterials. 2010 Sep 25; Authors: Kim JH, Park JS, Yang HN, Woo DG, Jeon SY, Do HJ, Lim HY, Kim JM, Park KH In stem cell therapy, transfection of specific genes into stem cells is an important technique to induce cell differentiation. To perform gene transfection in human mesenchymal stem cells (hMSCs), we designed and fabricated a non-viral vector system for specific stem cell differentiation. Several kinds of gene carriers were evaluated with regard to their transfection efficiency and their ability to enhance hMSCs differentiation. Of these delivery vehicles, biodegradable poly (dl-lactic-co-glycolic acid) (PLGA) nanoparticles yielded the best results, as they complexed with high levels of plasmid DNA (pDNA), allowed robust gene expression in hMSCs, and induced chondrogenesis. Polyplexing with polyethylenimine (PEI) enhanced the cellular uptake of SOX9 DNA complexed with PLGA nanoparticles both in vitro and in vivo. The expression of enhanced green fluorescent protein (EGFP) and SOX9 increased up to 75% in hMSCs transfected with PEI/SOX9 complexed PLGA nanoparticles 2 days after transfection. SOX9 gene expression was evaluated by RT-PCR, real time-qPCR, glycosaminoglycan (GAG)/DNA levels, immunoblotting, histology, and immunofluorescence. PMID: 20875683 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Derivation and characterization of novel nonhuman primate embryonic stem cell lines from in vitro fertilized baboon preimplantation embryos. Stem Cells Dev. 2010 Sep 27; Authors: Chang TC, Liu YG, Eddy CA, Jacoby ES, Binkley PA, Brzyski RG, Schenken RS The development of nonhuman primate (NHP) embryonic stem cell (ESC) models hold great promise for cell-mediated treatment of debilitating diseases and to address numerous unanswered questions regarding the therapeutic efficacy of ESCs while supplanting ethical considerations involved with human studies. Here we report successful establishment and characterization of three novel baboon (Papio cynocephalus) ESC lines from the inner cell mass (ICM) of intracytoplasmic sperm injection (ICSI)-derived blastocysts. Embryos were cultured in an improved baboon embryo in vitro culture protocol. The ICM of blastocyst was laser-dissected and plated on mouse embryonic fibroblast feeder (MEF) cell monolayer in NHP ESC culture medium. Three cell lines with characteristic ESC morphology have been cultured through an extended period (>14 months), with two male cell lines (UT-1 and -2) and one female cell line (UT-3) displaying normal baboon karyotypes. RT-PCR analysis confirmed all three lines express primate ESC pluripotency markers including Oct-4, NANOG, SOX-2, TERT, TDGF, LEFTYA, and REX-1. All 3 lines demonstrated positive immunocytochemical staining for Oct-4, SSEA-3, SSEA-4, TRA-1-60, and TRA-1-81. Baboon ESCs injected into NOD/SCID mice formed teratomas with all three germ layers. In addition, embryoid body-like spherical structures were derived and initial outgrowth was observed when embedded into extracellular matrix (Matrigel). The ESC lines established in this NHP model have the potential to extend our knowledge in the fields of developmental biology, regenerative medicine, and future applications including preclinical safety assessment of in vivo stem cell therapy. PMID: 20874104 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Composite scaffolds: Bridging nanofiber and microsphere architectures to improve bioactivity of mechanically competent constructs. J Biomed Mater Res A. 2010 Sep 28; Authors: Brown JL, Peach MS, Nair LS, Kumbar SG, Laurencin CT Tissue engineering often benefits from the use of composites to produce an ideal scaffold. We present the focused development of a novel structure that combines the biomimetic properties of nanofibers with the robust mechanical aspects of the sintered microsphere scaffold to produce a composite scaffold that demonstrates an ability to mimic the mechanical environment of trabecular bone while also promoting the phenotype progression of osteoblast progenitor cells. These composite nanofiber/microsphere scaffolds exhibited a mechanical modulus and compressive strength similar to trabecular bone and exhibited degradation resulting in a mass loss of 30% after 24 weeks. The nanofiber portion of these scaffolds was sufficiently porous to allow cell migration throughout the fibrous portion of the scaffold and promoted phenotype progression through focal adhesion kinase-mediated activation of the transcription factor Runx2, control scaffolds not containing nanofibers did not demonstrate extensive cell migration or phenotype progression. Ultimately, the focal adhesion kinase activity on the composite nanofiber/microsphere scaffolds demonstrated causality over the production of the mature osteoblast marker, osteocalcin, and the development of a calcified matrix. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20878987 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The synthesis and characterization of nanophase hydroxyapatite using a novel dispersant-aided precipitation method. J Biomed Mater Res A. 2010 Sep 28; Authors: Cunniffe GM, O'Brien FJ, Partap S, Levingstone TJ, Stanton KT, Dickson GR The synthesis of nanophase hydroxyapatite (nHA) is of importance in the field of biomaterials and bone tissue engineering. The bioactive and osteoconductive properties of nHA are of much benefit to a wide range of biomedical applications such as producing bone tissue engineered constructs, coating medical implants, or as a carrier for plasmid DNA in gene delivery. This study aimed to develop a novel low-temperature dispersant-aided precipitation reaction to produce nHA particles (<100 nm), which are regarded as being preferable to micron-sized agglomerates of nHA. The variables investigated and optimized include the reaction pH, the rate of reactant mixing, use of sonication, order of addition, and concentration of the primary reactants, in addition, the effect of using poly(vinyl alcohol) (PVA) surfactant and Darvan 821A® dispersing agent during the reaction was also examined. It was found that by fine-tuning the synthesis parameters and incorporating the dispersing agent, monodisperse, phase-pure nano-sized particles under 100 nm were attained, suitable for clinical applications in bone regeneration. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20878985 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biocompatibility and bioactivity of designer self-assembling nanofiber scaffold containing FGL motif for rat dorsal root ganglion neurons. J Biomed Mater Res A. 2010 Sep 28; Authors: Zou Z, Zheng Q, Wu Y, Guo X, Yang S, Li J, Pan H We report here a designer self-assembling peptide nanofiber scaffold developed specifically for nerve tissue engineering. We synthesized a peptide FGL-RADA containing FGL (EVYVVAENQQGKSKA), the motif of neural cell adhesion molecule (NCAM), and then attended to make a FGL nanofiber scaffold (FGL-NS) by assembling FGL-RADA with the peptide RADA-16 (AcN-RADARADARADARADA-CONH2). The microstructures of the scaffolds were tested using atomic force microscopy (AFM), and rheological properties of materials were accessed. Then we demonstrated the biocompatibility and bioactivity of FGL-NS for rat dorsal root ganglion neurons (DRGn). We found that the designer self-assembling peptide scaffold was noncytotoxic to neurons and able to promote adhesion and neurite sprouting of neurons. Our results indicate that the designer peptide scaffold containing FGL had excellent biocompatibility and bioactivity with adult sensory neurons and could be used for neuronal regeneration. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20878982 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biocompatibility evaluation of HDPE-UHMWPE reinforced β-TCP nanocomposites using highly purified human osteoblast cells. J Biomed Mater Res A. 2010 Sep 28; Authors: Shokrgozar MA, Farokhi M, Rajaei F, Bagheri MH, Azari S, Ghasemi I, Mottaghitalab F, Azadmanesh K, Radfar J Biocompatibility of β-TCP/HDPE-UHMWPE nanocomposite as a new bone substitute material was evaluated by using highly purified human osteoblast cells. Human osteoblast cells were isolated from bone tissue and characterized by immunofluorescence Staining before and after purification using magnetic bead system. Moreover, proliferation, alkaline phosphatase production, cell attachment, calcium deposition, gene expression, and morphology of osteoblast cells on β-TCP/HDPE-UHMWPE nanocomposites were evaluated. The results have shown that the human osteoblast cells were successfully purified and were suitable for subsequent cell culturing process. The high proliferation rate of osteoblast cells on β-TCP/HDPE-UHMWPE nanocomposite confirmed the great biocompatibility of the scaffold. Expression of bone-specific genes was taken place after the cells were incubated in composite extract solutions. Furthermore, osteoblast cells were able to mineralize the matrix next to composite samples. Scanning electron microscopy demonstrated that cells had normal morphology on the scaffold. Thus, these results indicated that the nanosized β-TCP/HDPE-UHMWPE blend composites could be potential scaffold, which is used in bone tissue engineering. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20878932 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Enhanced osteoblastic differentiation of mesenchymal stem cells seeded in RGD-functionalized PLLA scaffolds and cultured in a flow perfusion bioreactor. J Tissue Eng Regen Med. 2010 Sep 27; Authors: Alvarez-Barreto JF, Landy B, Vangordon S, Place L, Deangelis PL, Sikavitsas VI The present study combines chemical and mechanical stimuli to modulate the osteogenic differentiation of mesenchymal stem cells (MSCs). Arg-Gly-Asp (RGD) peptides incorporated into biomaterials have been shown to upregulate MSC osteoblastic differentiation. However, these effects have been assessed under static culture conditions, while it has been reported that flow perfusion also has an enhancing effect on MSC osteoblastic differentiation. It is clear that there is a need to combine RGD modification of biomaterials with mechanical stimulation of MSCs via flow perfusion and evaluate its effects on MSC differentiation down the osteogenic lineage. In this study, the effect of different levels of RGD modification of poly(L-lactic acid) scaffolds on MSC osteogenesis was evaluated under conditions of flow perfusion. It was found that there is a synergistic enhancement of different osteogenic markers, due to the combination of flow perfusion and RGD surface modification when compared to their individual effects. Furthermore, under conditions of flow perfusion, there is an RGD surface concentration optimal for differentiation, and it is flow rate-dependent. This report underlines the significance of incorporating combined biomimesis via biochemical and mechanical microenvironments that modulate in vivo cell behaviour and tissue function for more efficient tissue-engineering strategies. Copyright © 2010 John Wiley & Sons, Ltd. PMID: 20878644 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biomedical applications of dendrimers: a tutorial. Chem Soc Rev. 2010 Sep 28; Authors: Mintzer MA, Grinstaff MW Since their development in the mid-80s, dendrimers have become prominent synthetic macromolecules in the field of biomedical science. This tutorial review begins by discussing pertinent background information about dendrimers, focusing on their behavior in solution, how they are synthesized and what advantages they have over linear polymers. Then the focus of the review shifts to the biomedical applications of dendrimers, including their use in drug delivery, tissue engineering, gene transfection, and contrast enhancement for magnetic resonance imaging. This tutorial review is written for first-year graduate students or senior undergraduates and "asks" and "answers" many of the questions that arise in our first discussions of dendrimers. PMID: 20877875 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Characterization of hydrogel microstructure using laser tweezers particle tracking and confocal reflection imaging. J Phys Condens Matter. 2010;22(19):194121 Authors: Kotlarchyk MA, Botvinick EL, Putnam AJ Hydrogels are commonly used as extracellular matrix mimetics for applications in tissue engineering and increasingly as cell culture platforms with which to study the influence of biophysical and biochemical cues on cell function in 3D. In recent years, a significant number of studies have focused on linking substrate mechanical properties to cell function using standard methodologies to characterize the bulk mechanical properties of the hydrogel substrates. However, current understanding of the correlations between the microstructural mechanical properties of hydrogels and cell function in 3D is poor, in part because of a lack of appropriate techniques. Here we have utilized a laser tracking system, based on passive optical microrheology instrumentation, to characterize the microstructure of viscoelastic fibrin clots. Trajectories and mean square displacements were observed as bioinert PEGylated (PEG: polyethylene glycol) microspheres (1, 2 or 4.7 μm in diameter) diffused within confined pores created by the protein phase of fibrin hydrogels. Complementary confocal reflection imaging revealed microstructures comprised of a highly heterogeneous fibrin network with a wide range of pore sizes. As the protein concentration of fibrin gels was increased, our quantitative laser tracking measurements showed a corresponding decrease in particle mean square displacements with greater resolution and sensitivity than conventional imaging techniques. This platform-independent method will enable a more complete understanding of how changes in substrate mechanical properties simultaneously influence other microenvironmental parameters in 3D cultures. PMID: 20877437 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Electrospinning of fibrous polymer scaffolds using positive voltage or negative voltage: a comparative study. Biomed Mater. 2010 Sep 28;5(5):054110 Authors: Tong HW, Wang M Electrospinning of fibrous tissue engineering scaffolds has been traditionally conducted using positive voltages. In the current study, positive voltage (PV) electrospinning and negative voltage (NV) electrospinning were investigated for forming fibrous membranes of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV). In both PV-electrospinning and NV-electrospinning, the fiber diameter generally increased with increasing needle inner diameter and PHBV concentration but decreased with increasing working distance. The use of a conductivity-enhancing surfactant, benzyl triethylammonium chloride (BTEAC), significantly reduced PHBV fiber diameters from the micron scale to the sub-micron scale. Interestingly, with increasing applied voltage, the fiber diameter increased for PV-electrospinning but decreased for NV-electrospinning. The PV-electrospun fibrous membranes from solutions without BTEAC (PVEfm) and with BTEAC (PVEfm-B) and NV-electrospun membranes from solutions without BTEAC (NVEfm) and with BTEAC (NVEfm-B) were characterized in terms of their structure, wettability, thermal properties and tensile properties. Both PVEfm and NVEfm exhibited similar water contact angles (∼104°) but the contact angle of PVEfm-B or NVEfm-B was not measurable. The elongation at break of PVEfm-B or NVEfm-B was significantly higher than that of PVEfm or NVEfm. Using NV-electrospinning or a combination of NV- and PV-electrospinning may be very useful for developing suitable scaffolds for tissue engineering applications. PMID: 20876963 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Interactions between chitosan and cells measured by AFM. Biomed Mater. 2010 Sep 28;5(5):054117 Authors: Hsiao SW, Thien DV, Ho MH, Hsieh HJ, Li CH, Hung CH, Li HH Chitosan, a biocompatible material that has been widely used in bone tissue engineering, is believed to have a high affinity to osteoblastic cells. This research is the first to prove this hypothesis. By using atomic force microscopy (AFM) with a chitosan-modified cantilever, quantitative evaluation of the interforce between chitosan and cells was carried out. A chitosan tip functionalized with Arg-Gly-Asp (RGD) was also used to measure the interforce between RGD-chitosan and osteoblastic cells. This research concluded by examining cell adhesion and spreading of chitosan substrates as further characterization of the interactions between cells and chitosan. The force measured by AFM showed that the interforce between chitosan and osteoblasts was the highest (209 nN). The smallest adhesion force (61.8 nN) appeared between chitosan and muscle fibroblasts, which did not demonstrate any osteoblastic properties. This result proved that there was a significant interaction between chitosan and bone cells, and correlated with the observations of cell attachment and spreading. The technique developed in this research directly quantified the adhesion between chitosan and cells. This is the first study to demonstrate that specific interaction exists between chitosan and osteoblasts. PMID: 20876961 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Electrospinning, characterization and in vitro biological evaluation of nanocomposite fibers containing carbonated hydroxyapatite nanoparticles. Biomed Mater. 2010 Sep 28;5(5):054111 Authors: Tong HW, Wang M, Li ZY, Lu WW Poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) fibers containing carbonated hydroxyapatite (CHA) nanoparticles with different CHA amounts (5, 10 and 15 wt%) were electrospun with the aid of ultrasonic power for dispersing the nanoparticles. Scanning electron microscopy and energy-dispersive x-ray spectroscopy results showed that the distribution of CHA within the CHA/PHBV nanocomposite fibers was homogeneous when the CHA content was 10 wt%. Slight particle agglomeration occurred when the CHA content was 15 wt%. The diameters of the electrospun CHA/PHBV nanocomposite fibers and PHBV polymer fibers were around 3 µm. Fourier transform infrared spectroscopic analysis further confirmed the presence of CHA in CHA/PHBV nanocomposite fibers. Both PHBV and CHA/PHBV fibrous membranes exhibited similar tensile properties. Compared with PHBV solvent-cast film, the PHBV fibrous membrane was hydrophobic but the incorporation of CHA nanoparticles dramatically enhanced its wettability. In vitro studies revealed that both types of electrospun fibrous membranes (PHBV and CHA/PHBV) supported the proliferation of human osteoblastic cells (SaOS-2). The alkaline phosphatase activity of SaOS-2 cells seeded on the CHA/PHBV fibrous membranes was higher than that of the cells seeded on the PHBV fibrous membranes after 14 days of cell culture. The electrospun CHA/PHBV nanocomposite fibrous membranes show promises for bone tissue engineering applications. PMID: 20876957 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Cellular compatibility of RGD-modified chitosan nanofibers with aligned or random orientation. Biomed Mater. 2010 Sep 28;5(5):054112 Authors: Wang YY, Lü LX, Feng ZQ, Xiao ZD, Huang NP Aligned and randomly oriented chitosan nanofibers were prepared by electrospinning. The fibers were modified with the RGD cell-adhesive peptide through a heterobifunctional crosslinker containing a segment of poly(ethylene glycol) (PEG). PEG rendered the surface hydrophilic and provided flexible spacers, allowing the preservation of the bioactivity of further captured RGD peptides. NIH 3T3 cells were used to test the cellular compatibility of these chitosan nanofibrous scaffolds. Cell morphology and viability were investigated by SEM, fluorescent staining and cell counting. The results indicate that RGD-modified surfaces significantly improve the cellular compatibility of chitosan nanofibers and suggest a good candidate as a scaffold employed in tissue engineering. PMID: 20876956 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Differential Adhesiveness and Neurite-promoting Activity for Neural Cells of Chitosan, Gelatin, and Poly-L-Lysine Films. J Biomater Appl. 2010 Sep 28; Authors: MartÃn-López E, Nieto-DÃaz M, Nieto-Sampedro M Chitosan (Ch) and some of its derivatives have been proposed as good biomaterials for tissue engineering, to construct scaffolds promoting tissue regeneration. In this work we made composite films from Ch and mixtures of Ch with gelatin (G) and poly-L-lysine (PLL), and evaluated the growth on these films of PC12 and C6 lines as well as neurons and glial cells derived from cerebral tissue and dorsal root ganglia (DRG). C6 glioma cells proliferated on Ch, G, and Ch + G films, although metabolic activity was decreased by the presence of the G in the mixtures. NGF-differentiated PC12 cells, adhered preferentially on Ch and films containing PLL. Unlike NGF-treated PC12 cells, cortical and hippocampal neurons showed good adhesion to Ch and Ch + G films, where they extended neurites. Astrocytes adhered on Ch, Ch + G, and Ch + PLL mixtures, although viability decreased during the culture time. Olfactory ensheathing cells (OEC) adhered and proliferated to confluency on the wells covered with Ch + G films. Neurites from DRGs exhibited high extension on these films. These results demonstrate that Ch + G films have excellent adhesive properties for both neurons and regeneration-promoting glia (OEC). These films also promoted neurite extension from DRG, making them good candidates for tissue engineering of nerve repair. PMID: 20876636 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Recombinant spider silk as matrices for cell culture. Biomaterials. 2010 Sep 26; Authors: Widhe M, Bysell H, Nystedt S, Schenning I, Malmsten M, Johansson J, Rising A, Hedhammar M The recombinant miniature spider silk protein, 4RepCT, was used to fabricate film, foam, fiber and mesh matrices of different dimensionality, microstructure and nanotopography. These matrices were evaluated regarding their suitability for cell culturing. Human primary fibroblasts attached to and grew well on all matrix types, also in the absence of serum proteins or other animal-derived additives. The highest cell counts were obtained on matrices combining film and fiber/mesh. The cells showed an elongated shape that followed the structure of the matrices and exhibited prominent actin filaments. Moreover, the fibroblasts produced, secreted and deposited collagen type I onto the matrices. These results, together with findings of the matrices being mechanically robust, hold promise not only for in vitro cell culturing, but also for tissue engineering applications. PMID: 20875917 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Functional analysis of a murine monoclonal antibody against the repetitive region of the fibronectin-binding adhesins fibronectin-binding protein A and fibronectin-binding protein B from Staphylococcus aureus. FEBS J. 2010 Aug 31; Authors: Provenza G, Provenzano M, Visai L, Burke FM, Geoghegan JA, Stravalaci M, Gobbi M, Mazzini G, Arciola CR, Foster TJ, Speziale P Fibronectin-binding proteins A and B are multifunctional LPXTG staphylococcal adhesins, comprising an N-terminal region that binds fibrinogen and elastin, and a C-terminal domain that interacts with fibronectin. The C-terminal domain of fibronectin-binding protein A is organized into 11 tandem repeats, six of which bind the ligand with high affinity; other sites bind more weakly. Fibronectin-binding protein B has been postulated to harbor 10 rather than 11 repeats, but it contains the same number of high-affinity fibronectin-binding sites as fibronectin-binding protein A. In this study, we confirm this prediction and show that six of 10 sites bind with dissociation constants in the nanomolar range. We also found that the full-length repetitive region of fibronectin-binding protein B stimulated the production of a mAb (15E11) that binds with high affinity to an epitope shared by repeats 9 and 10 from both adhesins. With the use of truncated fragments of repeat 9 of fibronectin-binding protein A, we mapped the antibody epitope to the N-terminal segment and the fibronectin-binding site to the C-terminal segment of the repeat. The distinct localization of the 15E11 epitope and the fibronectin-binding site suggests that the interfering effect of the antibody might result from steric hindrance or a conformational change in the structure that reduces the accessibility of fibronectin to its binding determinant. The epitope is well exposed on the surface of staphylococcal cells, as determined by genetic analyses, fluorescence microscopy, and flow cytometry. When incubated with cells of Staphylococcs aureus strains, 15E11 inhibits attachment of bacteria to surface-coated fibronectin by almost 70%. Structured digital abstract: •  MINT-7991189, MINT-7991227, MINT-7991305, MINT-7991292, MINT-7991279, MINT-7991266, MINT-7991253, MINT-7991622: fnbA (uniprotkb:P14738) binds (MI:0407) to Fibronectin (uniprotkb:P02751) by enzyme linked immunosorbent assay (MI:0411) •  MINT-7991435, MINT-7991636, MINT-7991447, MINT-7991462, MINT-7991477, MINT-7991492, MINT-7991507, MINT-7991522: fnbA (uniprotkb:P14738) binds (MI:0407) to Fibronectin (uniprotkb:P02751) by filter binding (MI:0049) •  MINT-7991577, MINT-7991594: fnbB (uniprotkb:Q53682) binds (MI:0407) to Fibronectin (uniprotkb:P02751) by surface plasmon resonance (MI:0107) •  MINT-7991321, MINT-7991345, MINT-7991360, MINT-7991375, MINT-7991390, MINT-7991405, MINT-7991420: fnbB (uniprotkb:Q53682) binds (MI:0407) to Fibronectin (uniprotkb:P02751) by filter binding (MI:0049) •  MINT-7991103, MINT-7991114, MINT-7991126, MINT-7991138, MINT-7991153, MINT-7991165, MINT-7991177: fnbB (uniprotkb:Q53682) binds (MI:0407) to Fibronectin (uniprotkb:P02751) by enzyme linked immunosorbent assay (MI:0411) •  MINT-7991540, MINT-7991558: fnbA (uniprotkb:P14738) binds (MI:0407) to Fibronectin (uniprotkb:P02751) by surface plasmon resonance (MI:0107). PMID: 20875085 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Selective Activation of Sphingosine 1-Phosphate Receptors 1 and 3 Promotes Local Microvascular Network Growth. Tissue Eng Part A. 2010 Sep 27; Authors: Sefcik LS, Petrie Aronin C, Awojoodu A, Shin SJ, Mac Gabhann F, Macdonald TL, Wamhoff BR, Lynch KR, Peirce SM, Botchwey E Proper spatial and temporal regulation of microvascular remodeling is critical to the formation of functional vascular networks, spanning the various arterial, venous, capillary, and collateral vessel systems. Recently, our group has demonstrated that sustained release of sphingosine 1-phosphate (S1P) from biodegradable polymers promotes microvascular network growth and arteriolar expansion. In this study, we employed S1P receptor-specific compounds to activate and antagonize different combinations of S1P receptors to elucidate those receptors most critical for promotion of pharmacologically-induced microvascular network growth. We show that S1P1 and S1P3 receptors act synergistically to enhance functional network formation via increased functional length density, arteriolar diameter expansion, and increased vascular branching in the dorsal skinfold window chamber model. FTY720, a potent activator of S1P1 and S1P3, promoted a 107% and 153% increase in length density 3 and 7 days after implantation, respectively. It also increased arteriolar diameters by 60% and 85% 3 and 7 days after implantation. FTY720 stimulated branching in venules significantly more than unloaded PLAGA. When implanted on the mouse spinotrapezius muscle, FTY720 stimulated an arteriogenic response characterized by increased tortuosity and collateralization of branching microvascular networks. Our results demonstrate the effectiveness of S1P1 and S1P3 receptor-selective agonists (such as FTY720) in promoting microvascular growth and tissue engineering. PMID: 20874260 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Application of smart nanostructures in medicine. Nanomedicine (Lond). 2010 Sep;5(7):1129-38 Authors: He J, Qi X, Miao Y, Wu HL, He N, Zhu JJ Smart nanostructures are sensitive to various environmental or biological parameters. They offer great potential for numerous biomedical applications such as monitoring, diagnoses, repair and treatment of human biological systems. The present work introduces smart nanostructures for biomedical applications. In addition to drug delivery, which has been extensively reported and reviewed, increasing interest has been observed in using smart nanostructures to develop various novel techniques of sensing, imaging, tissue engineering, biofabrication, nanodevices and nanorobots for the improvement of healthcare. PMID: 20874025 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Platelet gel from cord blood: A novel tool for tissue engineering. Platelets. 2010 Sep 27; Authors: Parazzi V, Lazzari L, Rebulla P Recent findings show that growth factors (GF) play a relevant role in regenerative medicine. Platelets (PLT) may be used as “drug-stores” of GF that can be released upon activation by PLT granules. In this context, PLT gel (PG) from peripheral blood is currently used to improve tissue healing in orthopedic, oral maxillofacial and dermatologic surgery. Recent findings on multiple biological properties of human umbilical cord blood (CB) and its high level of viral safety prompted us to investigate the characteristics of its PLTs and the possibility to produce PLT gel from cord blood. Our study shows that CB PG releases high levels of vascular endothelial growth factor (VEGF) and platelet-derived growth factor-BB (PDGF-BB), substantial amounts of fibroblast growth factor (FGF), hepatocyte growth factor (HGF) and transforming growth factor-beta 1 (TGFbeta1), and minimal amounts of PDGF-AB. These findings suggest that CB PG can be a preferable tool for tissue engineering applications where high levels of VEGF and PDGF may be desirable. PMID: 20873963 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Effect of PEGylation on the Toxicity and Permeability Enhancement of Chitosan. Biomacromolecules. 2010 Sep 27; Authors: Casettari L, Vllasaliu D, Mantovani G, Howdle SM, Stolnik S, Illum L The aim of the present work is to investigate if conditions can be devised where PEGylation of chitosan would reduce its toxicity toward the nasal mucosa while maintaining its ability to open the cellular tight junctions and, consequently, produce an enhancement of macromolecular permeability. A series of mPEG-g-chitosan copolymers with varying levels of mPEG substitution, mPEG molecular weight, and chitosan molecular weight were synthesized by grafting carboxylic acid-terminated mPEGs (M(w) 1.9 and 5.0 × 10(3) g mol(-1)) to chitosans (M(w) 28.9 and 82.0 × 10(3) g mol(-1)) using a NHS/EDC coupling system. The synthesized mPEG-g-chitosans were fully characterized using a number of techniques, including FT-IR, (1)H NMR, and SEC-MALLS and their physicochemical properties were analyzed by TGA and DSC. Thereafter, the conjugates were tested for their cytotoxicity and tight junction modulating property in a relevant cell model, a mucus producing Calu-3 monolayer. mPEG-g-chitosan conjugates exhibited reduced toxicity toward cells, as compared to unmodified chitosan counterparts. Furthermore, the conjugates demonstrated a dramatic effect on cell monolayer transepithelial electrical resistance (TEER) and enhancement of permeability of model macromolecules. TEER and permeability-enhancing effects, as measurable indicators of tight junction modulation, were found to be pH-dependent and were notably more pronounced than those exhibited by unmodified chitosans. This work therefore demonstrates that conditions can be contrived where PEGylation improves the toxicity profile of chitosan, while preserving its effect on epithelial tight junctions in the nose. PMID: 20873757 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biomimetics for the induction of bone formation. Expert Rev Med Devices. 2010 Jul;7(4):469-79 Authors: Ripamonti U, Roden L The new strategy to initiate the induction of bone formation is to carve smart, self-inducing geometric cues assembled within biomimetic medical devices. These are endowed with the striking prerogative of differentiating myoblastic and/or pericytic stem cells into osteoblastic-like cells attached to the morphogenetic concavities; osteoblastic-like cells secrete osteogenic gene products of the TGF-beta supergene family, further differentiating invading stem cells into osteoblastic-like cells, and initiating bone formation by induction as a secondary response. PMID: 20583884 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The antimicrobial peptide LL37 induces the migration of human pulp cells: a possible adjunct for regenerative endodontics. J Endod. 2010 Jun;36(6):1009-13 Authors: Kajiya M, Shiba H, Komatsuzawa H, Ouhara K, Fujita T, Takeda K, Uchida Y, Mizuno N, Kawaguchi H, Kurihara H INTRODUCTION: The antimicrobial peptide LL37 has multiple functions, such as the induction of angiogenesis and migration. Pulp cell migration is a key phenomenon in the early stage of pulp-dentin complex regeneration. In this study, we examined the effect of LL37 on the migration of human pulp (HP) cells. METHODS: HP cells at the sixth passage were exposed to LL37. The migration of HP cells was assessed by a wound-healing assay. The phosphorylation of epidermal growth factor receptor (EGFR) and c-Jun N-terminal kinase (JNK) was analyzed by immunoblotting. RESULTS: LL37 as well as heparin binding (HB)-EGF, which is an agonist of EGFR, induced HP cell migration. LL37 increased the level of phosphorylated EGFR. An anti-EGFR antibody, an EGFR tyrosine kinase inhibitor, and a JNK inhibitor abolished the migration induced by both LL37 and HB-EGF. Furthermore, the two peptides increased the levels of phosphorylated JNK. CONCLUSIONS: LL37 activates EGFR and JNK to induce HP cell migration, and it may contribute to enhancing the regeneration of pulp-dentin complexes. PMID: 20478456 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
