|  |  |  | | | | | pubmed: "regenerative medici... | | | | | | | | | | | | | | | | | | | State-of-the-art techniques in operative dentistry: contemporary teaching of posterior composites in UK and Irish dental schools. Br Dent J. 2010 Aug 14;209(3):129-36 Authors: Lynch CD, Frazier KB, McConnell RJ, Blum IR, Wilson NH Aim Advances of composite systems and their application have revolutionised the management of posterior teeth affected by caries, facilitating a minimally invasive approach. Previous surveys have indicated that the teaching of posterior composites within dental schools was developing, albeit not keeping pace with clinical evidence and the development of increasingly predictable techniques and materials. Concurrently, surveys of dental practice indicate that dental amalgam still predominates as the 'material of choice' for the restoration of posterior teeth within UK general dental practice. In light of such considerations, the aim of this study was to investigate current teaching of posterior composites in Irish and UK dental schools.Methods An online questionnaire which sought information in relation to the current teaching of posterior composites was developed and distributed to the 17 established Irish and UK dental schools with undergraduate teaching programmes in late 2009.Results Completed responses were received from all 17 schools (response rate = 100%). All 17 schools taught the placement of occlusal and two-surface occlusoproximal composites in premolar and permanent molar teeth. Two schools did not teach placement of three-surface occlusoproximal composites in either premolars or molars. In their preclinical courses, ten schools taught posterior composites before teaching dental amalgams. Fifty-five percent of posterior restorations placed by dental students were of composite (range = 10-90%) and 44% amalgam (range = 10-90%), indicating an increase of 180% in the numbers of posterior composites placed over the past five years. Diversity was noted in the teaching of clinical techniques and students at different schools are trained with different composites and bonding systems. Some cause for concern was noted in the teaching of certain techniques that were not in keeping with existing best evidence, such as the teaching of transparent matrix bands and light-transmitting wedges for occluso-proximal composites (eight schools) and the teaching of bevels on the cavosurface enamel margins of both the occlusal and proximal box margins (three schools).Conclusion The teaching of posterior composites in the Irish and UK dental schools has substantially increased over the last five years. Dental students in these schools often gain more experience in the placement of posterior composites than amalgam. However, practice trends indicate that a majority of GDPs continue to place amalgam in preference to composite, thereby suggesting a source of tension as current dental students emerge into the dental workforce over the coming years. There is, as a consequence, a challenge to the dental profession and its funding agencies in the UK to encourage more of a shift towards the minimally interventive use of composite systems in the restoration of posterior teeth, in particular among established practitioners. PMID: 20706252 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The Future of Cell Transplant Therapies: A Need for Tissue Grafting. Transplantation. 2010 Aug 11; Authors: Turner R, Gerber D, Reid L Current methodologies of solid organ-derived cell transplant therapies introduce donor cells into hosts through a vascular route, a strategy modeled after hematopoietic therapies. These strategies fail because of inefficient engraftment, poor survival of the cells, and propensity for formation of life-threatening emboli. Transplant success necessitates grafting methods, requiring a mixture of appropriate cell sources embedded into or onto precise mixes of extracellular matrix components and then localized to the diseased or dysfunctional tissue, promoting necessary proliferation, engraftment, and vascularization. Grafting technologies are rapidly translatable to therapeutic uses in patients and provide alternative treatments for regenerative medicine. PMID: 20706179 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Enhancing research in regenerative medicine. Blood. 2010 Aug 12;116(6):866-7 Authors: Williams DA, Keating A PMID: 20705767 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The expansion of T-cells and hematopoietic progenitors as a result of overexpression of the lymphoblastic leukemia gene, Lyl1 can support leukemia formation. Leuk Res. 2010 Aug 10; Authors: Lukov GL, Rossi L, Souroullas GP, Mao R, Goodell MA This study investigates the function of the lymphoblastic leukemia gene, Lyl1 in the hematopoietic system and its oncogenic potential in the development of leukemia. Overexpression of Lyl1 in mouse bone marrow cells caused T-cell increase in the peripheral blood and expansion of the hematopoietic progenitors in culture and in the bone marrow. These observations were the result of increased proliferation and suppressed apoptosis of the progenitor cells caused by the Lyl1-overexpression. Our studies present substantial evidence supporting the secondary, pro-leukemic effect of Lyl1 in early hematopoietic progenitors with the potential to cause expansion of malignant cells with a stem/early progenitor-like phenotype. PMID: 20705338 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Functionalization of Hyaluronic Acid with Chemoselective Groups via a Disulfide-Based Protection Strategy for In Situ Formation of Mechanically Stable Hydrogels. Biomacromolecules. 2010 Aug 12; Authors: Ossipov DA, Piskounova S, Varghese OP, Hilborn J Functionalization of hyaluronic acid (HA) with chemoselective groups enables in situ (in vivo) formation of HA-based materials in minimally invasive injectable manner. Current methods of HA modification with such groups primarily rely on the use of a large excess of a reagent to introduce a unique reactive handle into HA and, therefore, are difficult to control. We have developed the new protective group strategy based on initial mild cleavage of a disulfide bond followed by elimination of the generated 2-thioethoxycarbonyl moiety ultimately affording free amine-type functionality, such as hydrazide, aminooxy, and carbazate. Specifically, new modifying homobifunctional reagents have been synthesized that contain a new divalent disulfide-based protecting group. Amidation of HA with these reagents gives rise to either one-end coupling product or to intra/intermolecular cross-linking of the HA chains. However, after subsequent treatment of the amidation reaction mixture with dithiothreitol (DTT), these cross-linkages are cleaved, ultimately exposing free amine-type groups. The same methodology was applied to graft serine residues to the HA backbone, which were subsequently oxidized into aldehyde groups. The strategy therefore encompasses a new approach for mild and highly controlled functionalization of HA with both nucleophilic and electrophilic chemoselective functionalities with the emphasis for the subsequent conjugation and in situ cross-linking. A series of new hydrogel materials were prepared by mixing the new HA-aldehyde derivative with different HA-nucleophile counterparts. Rheological properties of the formed hydrogels were determined and related to the structural characteristics of the gel networks. Human dermal fibroblasts remained viable while cultured with the hydrogels for 3 days, with no sign of cytotoxicity, suggesting that the gels described in this study are candidates for use as growth factors delivery vehicles for tissue engineering applications. PMID: 20704177 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Establishment of immortalized periodontal ligament progenitor cell line and its behavioural analysis on smooth and rough titanium surface. Eur Cell Mater. 2010;19:228-41 Authors: Docheva D, Padula D, Popov C, Weishaupt P, Prägert M, Miosge N, Hickel R, Böcker W, Clausen-Schaumann H, Schieker M Periodontal ligament (PDL) can be obtained from patients undergoing orthodontic treatment. PDL contains progenitor cells that can be expanded and differentiated towards several mesenchymal lineages in vitro. Furthermore, PDL-derived cells have been shown to generate bone- and PDL-like structures in vivo. Thus, PDL cells, combined with suitable biomaterials, represent a promising tool for periodontitis-related research and PDL engineering. Here, a new PDL cell line using lentiviral gene transfer of human telomerase reverse transcriptase (hTERT) was created. HTERT-expressing PDL cells showed similar morphology and population doubling time but an extended lifespan compared to the primary cells. In addition, PDL-hTERT cells expressed several characteristic genes and upon osteogenic stimulation produced a calcified matrix in vitro. When cultivated on two topographically different titanium scaffolds (MA and SLA), PDL-hTERT cells exhibited augmented spreading, survival and differentiation on smooth (MA) compared to rough (SLA) surfaces. These findings differ from previously reported osteoblast behaviour, but they are in agreement with the behaviour of chondrocytes and gingival fibroblasts, suggesting a very cell type-specific response to different surface textures. In summary, we report the testing of titanium biomaterials using a new PDL-hTERT cell line and propose this cell line as a useful model system for periodontitis research and development of novel strategies for PDL engineering. PMID: 20473831 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Bacterial biofilm formation versus mammalian cell growth on titanium-based mono- and bi-functional coating. Eur Cell Mater. 2010;19:205-13 Authors: Subbiahdoss G, Pidhatika B, Coullerez G, Charnley M, Kuijer R, van der Mei HC, Textor M, Busscher HJ Biomaterials-associated-infections (BAI) are serious complications in modern medicine. Although non-adhesive coatings, like polymer-brush coatings, have been shown to prevent bacterial adhesion, they do not support cell growth. Bi-functional coatings are supposed to prevent biofilm formation while supporting tissue integration. Here, bacterial and cellular responses to poly(ethylene glycol) (PEG) brush-coatings on titanium oxide presenting the integrin-active peptide RGD (arginine-glycine-aspartic acid) (bioactive "PEG-RGD") were compared to mono-functional PEG brush-coatings (biopassive "PEG") and bare titanium oxide (TiO2) surfaces under flow. Staphylococcus epidermidis ATCC 35983 was deposited on the surfaces under a shear rate of 11 s-1 for 2 h followed by seeding of U2OS osteoblasts. Subsequently, both S. epidermidis and U2OS cells were grown simultaneously on the surfaces for 48 h under low shear (0.14 s-1). After 2 h, staphylococcal adhesion was reduced to 3.6-/+1.8 x 103 and 6.0-/+3.9 x 103 cm-2 on PEG and PEG-RGD coatings respectively, compared to 1.3-/+0.4 x 105 cm-2 for the TiO2 surface. When allowed to grow for 48 h, biofilms formed on all surfaces. However, biofilms detached from the PEG and PEG-RGD coatings when exposed to an elevated shear (5.6 s-1) U2OS cells neither adhered nor spread on PEG brush-coatings, regardless of the presence of biofilm. In contrast, in the presence of biofilm, U2OS cells adhered and spread on PEG-RGD coatings with a significantly higher surface coverage than on bare TiO2. The detachment of biofilm and the high cell surface coverage revealed the potential significance of PEG-RGD coatings in the context of the "race for the surface" between bacteria and mammalian cells. PMID: 20467966 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Aligned electrospun polymer fibres for skeletal muscle regeneration. Eur Cell Mater. 2010;19:193-204 Authors: Aviss KJ, Gough JE, Downes S Skeletal muscle repair is often overlooked in surgical procedures and in serious burn victims. Creating a tissue-engineered skeletal muscle would not only provide a grafting material for these clinical situations, but could also be used as a valuable true-to-life research tool into diseases affecting muscle tissue. Electrospinning of the elastomer PLGA produced aligned fibres that had the correct topology to provide contact guidance for myoblast elongation and alignment. In addition, the electrospun scaffold required no surface modifications or incorporation of biologic material for adhesion, elongation, and differentiation of C2C12 murine myoblasts. PMID: 20467965 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The effect of electrospun fibre alignment on the behaviour of rat periodontal ligament cells. Eur Cell Mater. 2010;19:180-92 Authors: Shang S, Yang F, Cheng X, Walboomers XF, Jansen JA It is envisioned that for the regeneration of highly organized structures, like tendon and ligaments, only aligned fibrous scaffolds can provide adequate topographic guidance to cells. In this study, a novel method to electrospin an aligned scaffold is presented. Electrospun fibres were deposited into a water bath and then the fibres were drawn to a rotating mandrel in a controlled manner. In this way, parallel and cross-aligned fibrous poly (lactide-co-glycolide) (PLGA) scaffolds were fabricated, which were subsequently used to study their effect on the growth behaviour of rat periodontal ligament (PDL) cells. First, the scaffolds were characterized regarding mechanical properties, scaffold stability and degradation in vitro. Then, rat PDL cells were seeded and cultured on these scaffolds for up to 7 days. Randomly oriented PLGA and solvent cast plain PLGA films served as controls. Results showed that the alignment of fibres resulted in a higher tensile stress and Young's modulus. Aligned scaffolds maintained their structural stability better compared to the controls after incubation in phosphate-buffered saline for 6 weeks. Further, cells were observed to elongate along the fibre after 3 days of culture. Proliferation and migration of PDL cells was significantly more prevalent on the aligned fibres compared to the controls. It was concluded that aligned scaffolds seem to be able to promote the organized regeneration of periodontal tissue. PMID: 20419630 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Low-level Er:YAG laser irradiation enhances osteoblast proliferation through activation of MAPK/ERK. Lasers Med Sci. 2010 Jul;25(4):559-69 Authors: Aleksic V, Aoki A, Iwasaki K, Takasaki AA, Wang CY, Abiko Y, Ishikawa I, Izumi Y Although the use of high-level Er:YAG laser irradiation has been increasing in periodontal and peri-implant therapy, the effects of low-level Er:YAG laser on surrounding tissues and cells remain unclear. In the present study, the effects of low-level Er:YAG laser irradiation on osteoblast proliferation were investigated. Cells of the osteoblastic cell line MC3T3-E1 were treated with low-level Er:YAG laser irradiation with various combinations of laser settings (fluence 0.7-17.2 J/cm(2)) and in the absence or presence of culture medium during irradiation. On day 1 and/or day 3, cell proliferation and death were determined by cell counting and by measurement of lactate dehydrogenase (LDH) levels. Further, the role of mitogen-activated protein kinase (MAPK) pathways in laser-enhanced cell proliferation was investigated by inhibiting the MAPK pathways and then measuring MAPK phosphorylation by Western blotting. Higher proliferation rates were found with various combinations of irradiation parameters on days 1 and 3. Significantly higher proliferation was also observed in laser-irradiated MC3T3-E1 cells at a fluence of approximately 1.0-15.1 J/cm(2), whereas no increase in LDH activity was observed. Further, low-level Er:YAG irradiation induced the phosphorylation of extracellular signal-regulated protein kinase (MAPK/ERK) 5 to 30 min after irradiation. Although MAPK/ERK 1/2 inhibitor U0126 significantly inhibited laser-enhanced cell proliferation, activation of stress-activated protein kinases/Jun N-terminal kinase (SAPK/JNK) and p38 MAPK was not clearly detected. These results suggest that low-level Er:YAG laser irradiation increases osteoblast proliferation mainly by activation of MAPK/ERK, suggesting that the Er:YAG laser may be able to promote bone healing following periodontal and peri-implant therapy. PMID: 20186556 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | S100A8 and S100A9 in experimental osteoarthritis. Arthritis Res Ther. 2010;12(1):R16 Authors: Zreiqat H, Belluoccio D, Smith MM, Wilson R, Rowley LA, Jones K, Ramaswamy Y, Vogl T, Roth J, Bateman JF, Little CB INTRODUCTION: The objective was to evaluate the changes in S100A8 S100A9, and their complex (S100A8/S100A9) in cartilage during the onset of osteoarthritis (OA) as opposed to inflammatory arthritis. METHODS: S100A8 and S100A9 protein localization were determined in antigen-induced inflammatory arthritis in mice, mouse femoral head cartilage explants stimulated with interleukin-1 (IL-1), and in surgically-induced OA in mice. Microarray expression profiling of all S100 proteins in cartilage was evaluated at different times after initiation of degradation in femoral head explant cultures stimulated with IL-1 and surgically-induced OA. The effect of S100A8, S100A9 or the complex on the expression of aggrecan (Acan), collagen II (Col2a1), disintegrin and metalloproteases with thrombospondin motifs (Adamts1, Adamts 4 &Adamts 5), matrix metalloproteases (Mmp1, Mmp3, Mmp13 &Mmp14) and tissue inhibitors of metalloproteinases (Timp1, Timp2 &Timp3), by primary adult ovine articular chondrocytes was determined using real time quantitative reverse transcription polymerase chain reaction (qRT-PCR). RESULTS: Stimulation with IL-1 increased chondrocyte S100a8 and S100a9 mRNA and protein levels. There was increased chondrocyte mRNA expression of S100a8 and S100a9 in early but not late mouse OA. However, loss of the S100A8 staining in chondrocytes occurred as mouse OA progressed, in contrast to the positive reactivity for both S100A8 and S100A9 in chondrocytes in inflammatory arthritis in mice. Homodimeric S100A8 and S100A9, but not the heterodimeric complex, significantly upregulated chondrocyte Adamts1, Adamts4 and Adamts 5, Mmp1, Mmp3 and Mmp13 gene expression, while collagen II and aggrecan mRNAs were significantly decreased. CONCLUSIONS: Chondrocyte derived S100A8 and S100A9 may have a sustained role in cartilage degradation in inflammatory arthritis. In contrast, while these proteins may have a role in initiating early cartilage degradation in OA by upregulating MMPs and aggrecanases, their reduced expression in late stages of OA suggests they do not have an ongoing role in cartilage degradation in this non-inflammatory arthropathy. PMID: 20105291 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Identification, isolation and characterization of HCN4-positive pacemaking cells derived from murine embryonic stem cells during cardiac differentiation. Pacing Clin Electrophysiol. 2010 Mar;33(3):290-303 Authors: Morikawa K, Bahrudin U, Miake J, Igawa O, Kurata Y, Nakayama Y, Shirayoshi Y, Hisatome I BACKGROUND: Development of biological pacemaker is a potential treatment for bradyarrhythmias. Pacemaker cells could be extracted from differentiated embryonic stem (ES) cells based on their specific cell marker hyperpolarization-activated cyclic nucleotide-gated (HCN)4. The goal of this study was to develop a method of identification, isolation, and characterization of pacemaking cells derived from differentiated ES cells with GFP driven by HCN4 promoter. METHODS AND RESULTS: Polymerase chain reaction (PCR) screening and southern blot analysis revealed that HCN4p-EGFP trans-gene was stably integrated into the chromosome of mouse AB1 ES cells. RT-PCR and immunostaining results showed similar expression of the specific cardiac pacemaker markers of the HCN4p-EGFP ES cells and its parental AB1 ES cell lines. Although HCN4p-EGFP trans-gene may have slight effect on the general mesodermal differentiation, it had no effect on the pluripotency of ES cells, on the transcription of cardiac specific factors and cardiac contractile proteins, and on the capability of ES cells to differentiate into pacemaker cells. Electrophysiological study indicated that HCN4p-GFP-positive cells revealed the spontaneous action potential, which was slowed by the treatment with 2 mM Cs(+), and expressed the hyperpolarization-activeted cation current I(f) encoded by HCN4 gene. CONCLUSION: By the approach of using stable transfectant of HCN4p-EGFP gene, the identification, isolation, and characterization of ES cell-derived pacemaking cells could be carried out. PMID: 19895411 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
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