| Shear resistance of human umbilical endothelial cells on different materials covered with or without extracellular matrix: controlled in-vitro study.
August 29, 2009 at 12:19 pm
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| | Shear resistance of human umbilical endothelial cells on different materials covered with or without extracellular matrix: controlled in-vitro study. Clin Hemorheol Microcirc. 2009;43(1):157-66 Authors: Hoepken S, Fuhrmann R, Jung F, Franke RP A variety of medical grade polymeric materials are used in tissue engineering and biomedical technology. Dense non-porous polymeric foils were used as substrates for endothelial cell layers. Half a the test samples (polymers and control materials) were seeded with bovine corneal endothelial cells (BCEC) which more or less covered the substrates with an extracellular matrix (ECM) in the consecutive culturing period. Afterwards the ECM covered as well as the uncovered materials were seeded with human umbilical venous endothelial cells (HUVEC). HUVEC seeded samples were cultured either under static or under dynamical conditions in a cone/plate rheometer with a mean low arterial shear stress of 8.2 dyn/cm2 to simulate the flow conditions in a coronary vein graft. With the exemption of polyvinyl chloride all other materials could be coated with ECM at least partially. Under static conditions the best results with respect to complete coverage with ECM and HUVEC were seen on polyester and polyurethane. Under shear load, however, the complete HUVEC layer together with the ECM detached from the polymer surface within a short time. ECM and HUVEC remained no longer than 43 minutes on anyone of the materials tested. The materials as supplied and tested were clearly not appropriate as implants in contact to the flowing blood. PMID: 19713610 [PubMed - in process] |
| Poly(glycerol-dodecanoate), a biodegradable polyester for medical devices and tissue engineering scaffolds.
August 29, 2009 at 12:19 pm
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| | Poly(glycerol-dodecanoate), a biodegradable polyester for medical devices and tissue engineering scaffolds. Biomaterials. 2009 Aug 25; Authors: Migneco F, Huang YC, Birla RK, Hollister SJ In this paper we describe the mechanical and biological features of a thermosetting polyester synthesized from glycerol and dodecanedioic acid named Poly-Glycerol-Dodecanoate (PGD). This polymer shows a glass transition temperature (T(g)) around 32 degrees C, and this accounts for its mechanical properties. At room temperature (21 degrees ) PGD behaves like a stiff elastic-plastic material, while at body temperature (37 degrees C), it shows a compliant non-linear elastic behavior. Together with biodegradability and biocompatibility PGD has distinct shape memory features. After the polymer is cured, no matter what the final configuration is, we can recover the original shape by heating PGD to temperatures of 32 degrees C and higher. The mechanical properties together with biocompatibility/biodegradability and shape memory features make PGD an attractive polymer for biomedical applications. PMID: 19712970 [PubMed - as supplied by publisher] |
| Synthesis by AGET ATRP of Degradable Nanogel Precursors for In Situ Formation of Nanostructured Hyaluronic Acid Hydrogel.
August 29, 2009 at 12:19 pm
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| | Synthesis by AGET ATRP of Degradable Nanogel Precursors for In Situ Formation of Nanostructured Hyaluronic Acid Hydrogel. Biomacromolecules. 2009 Aug 27; Authors: Bencherif SA, Washburn NR, Matyjaszewski K A nanostructured hyaluronic acid (HA) hydrogel was prepared by a combination of atom transfer radical polymerization (ATRP) and Michael-type addition reaction. Biodegradable POEO(300)MA-co-PHEMA nanogels with pendent hydroxy groups were prepared by activators generated by electron transfer ATRP in cyclohexane inverse miniemulsion in the presence of a hydrolytically labile cross-linker. The hydroxy groups were subsequently modified with acryloyl chloride to form reactive acrylated-nanogels (ACRL-nanogels). These nanogels degrade upon hydrolysis into polymeric sols enabling controlled release of entrapped fluorescently labeled biomolecules, such as rhodamine B isothiocyanate-dextran used as a drug model. Thiol-derivatized HA (HA-SH) was prepared by carbodiimide-mediated coupling reaction of HA with cysteamine hydrochloride. The nanostructured hydrogel was formed by mixing HA-SH with ACRL-nanogels under physiological conditions (pH = 7.4, 37 degrees C). Gelation occurred within a few minutes after mixing the precursor liquid solution via a Michael-type addition reaction between unsaturated acrylated moieties and nucleophilic thiols, leading to a chemically cross-linked network. Formation of the nanostructured HA hydrogel was visually observed with digital images after gelation and hydration. The gel was analyzed by scanning electron microscopy for morphological observation. Surface morphology demonstrates that the nanostructured gel was well-constructed with a porous three-dimensional structure and uniform distribution of nanogels. This novel biodegradable scaffold hybridized with nanogels offers the advantage of selective, fast, in situ polymerization and potential as an injectable biocompatible matrix for cell and protein encapsulation in both tissue engineering and drug delivery applications. PMID: 19711888 [PubMed - as supplied by publisher] |
| Improvement in cell proliferation on silicone rubber by carbon nanotube coating.
August 29, 2009 at 12:19 pm
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| | Improvement in cell proliferation on silicone rubber by carbon nanotube coating. Biomed Mater Eng. 2009;19(2-3):155-62 Authors: Matsuoka M, Akasaka T, Hashimoto T, Totsuka Y, Watari F Silicone rubbers are widely used as tissue implants because of their flexibility and chemical stability. However, they have limited cellular adhesiveness and may cause problems in the long term. In this study, a coating of carbon nanotubes (CNTs) was applied to silicone rubber to improve its cellular adhesiveness. Scanning electron micrograph of this coating revealed that CNTs had formed a densely packed meshwork; the Ra values and protein adsorption capacity were enhanced. Although the contact angle did not change after coating, it decreased after immersion into a culture medium. After cultivation for 6 d, while Saos-2 cells were hardly observed on untreated silicone, the cells proliferated on CNT-coated silicone. Thus, CNT coating might be a simple and effective solution to problems associated with silicone implants. PMID: 19581709 [PubMed - indexed for MEDLINE] |
| Adhesion of human osteoblast-like cells (Saos-2) to carbon nanotube sheets.
August 29, 2009 at 12:19 pm
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| | Adhesion of human osteoblast-like cells (Saos-2) to carbon nanotube sheets. Biomed Mater Eng. 2009;19(2-3):147-53 Authors: Akasaka T, Yokoyama A, Matsuoka M, Hashimoto T, Abe S, Uo M, Watari F Carbon nanotubes (CNTs) exhibit excellent cell proliferation properties, which can serve as a scaffold for cell culturing. However, there are only a few reports on adhesion of osteoblast-like cells to a CNT sheet. In this study, we investigated adhesion of osteoblast-like cells to single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) sheets and compared these adhesions with that on a cell culture polystyrene dish by using a cell adhesion test and a scanning electron microscope. The MWNT sheets exhibited faster adhesion of cells at an initial stage than SWNT sheets and cell culture polystyrene dish. The number of attached cells on the MWNT sheets seemed to be greater than on SWNT sheets and cell culture polystyrene. Moreover, the MWNT sheets exhibited both high speed and good capacity for cell adhesion. However, the surface of the MWNT sheets was such that it facilitated cell adherence but hindered the spreading of the attached cells. Interestingly, cell adhesion to CNT sheets was significantly influenced by pre-coating with serum. These results indicate that CNT sheets would play an important role in adsorption of serum proteins, which would consequently facilitate cell adhesion, and that the MWNT sheets have a high cell adhesiveness. PMID: 19581708 [PubMed - indexed for MEDLINE] |
| A novel osteoclast precursor cell line, 4B12, recapitulates the features of primary osteoclast differentiation and function: enhanced transfection efficiency before and after differentiation.
August 29, 2009 at 12:19 pm
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| | A novel osteoclast precursor cell line, 4B12, recapitulates the features of primary osteoclast differentiation and function: enhanced transfection efficiency before and after differentiation. J Cell Physiol. 2009 Oct;221(1):40-53 Authors: Amano S, Sekine K, Bonewald LF, Ohmori Y Osteoclasts are bone-resorbing multinucleated cells differentiated from monocyte/macrophage lineage precursors. A novel osteoclast precursor cell line, 4B12 was established from Mac-1(+)c-Fms(+)RANK(+) cells from calvaria of 14-day-old mouse embryos using immunofluorescence and cell-sorting methods. Like M-CSF-dependent bone marrow macrophages (M-BMMs), M-CSF is required for 4B12 cells to differentiate into TRAP-positive multinucleated cells [TRAP(+) MNCs] in the presence of RANKL. Bone-resorbing osteoclasts differentiated from 4B12 cells on dentine slices possess both a clear zone and ruffled borders and express osteoclast-specific genes. Bone-resorbing activity, but not TRAP, was enhanced in the presence of IL-1alpha. The number of TRAP(+) MNCs and the number of pits formed from 4B12 cells on dentine slices was fourfold higher than that from M-BMMs. 4B12 cells were identified as macrophages with Mac-1 and F4/80, yet lost these markers upon differentiation into osteoclasts as determined by confocal laser scanning microscopy. The 4B12 cells do not have the potential to differentiate into dendritic cells indicating commitment to the osteoclast lineage. 4B12 cells are readily transfectable with siRNA transfection before and after differentiation. These data show that 4B12 cells faithfully replicate the properties of primary cells and are a useful and powerful model for analyzing the molecular and cellular regulatory mechanisms of osteoclastogenesis and osteoclast function. PMID: 19492422 [PubMed - indexed for MEDLINE] |
| Sulfonation of papain-treated chitosan and its mechanism for anticoagulant activity.
August 29, 2009 at 12:19 pm
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| | Sulfonation of papain-treated chitosan and its mechanism for anticoagulant activity. Carbohydr Res. 2009 Jul 6;344(10):1190-6 Authors: Suwan J, Zhang Z, Li B, Vongchan P, Meepowpan P, Zhang F, Mousa SA, Mousa S, Premanode B, Kongtawelert P, Linhardt RJ The novel low-molecular-weight chitosan polysulfate (MW 5120-26,200 Da) was prepared using the depolymerization of chitosan with papain (EC. 3.4.22.2). The sulfonation of depolymerized products was performed using chlorosulfonic acid in N,N-dimethylformamide under semi-heterogeneous conditions. The structures of the products were characterized by FTIR, (13)C NMR, and (1)H NMR (1D, 2D NMR) spectroscopy. The present study sheds light on the mechanism of anticoagulant activity of chitosan polysulfate. Anticoagulant activity was investigated by an activated partial thromboplastin assay, a thrombin time assay, a prothrombin time assay, and thrombelastography. Surface plasmon resonance also provided valuable data for understanding the relationship between the molecular binding of sulfated chitosan to two important blood clotting regulators, antithrombin III and heparin cofactor II. These results show that the principal mechanism by which this chitosan polysulfate exhibits anticoagulant activity is mediated through heparin cofactor II and is dependent on polysaccharide molecular weight. PMID: 19476923 [PubMed - indexed for MEDLINE] |
| The human olfactory mucosa.
August 29, 2009 at 10:45 am
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| | The human olfactory mucosa. Eur Arch Otorhinolaryngol. 2009 Aug 28; Authors: Escada PA, Lima C, Madeira da Silva J Studies of the tissues of the human olfactory mucosa have been performed to investigate olfactory dysfunction and, more recently, olfactory mucosa has attracted a novel interest of investigators because it can be used as an early marker of neurodegenerative conditions of the brain and as a source of multipotent neural stem cells, with applications in regenerative medicine. The olfactory mucosa is readily available to the otolaryngologist, but the harvesting of this tissue must be safe, effective, and reliable, obtaining as little tissue as necessary, while avoiding unnecessary harm to the remaining olfactory tissue and function. The purpose of this review is to summarize the results of the most important studies and knowledge with regard to the human olfactory mucosa and its applications, emphasizing the issue of the distribution of the olfactory mucosa in the nasal cavities. PMID: 19714350 [PubMed - as supplied by publisher] |
| Is There Such a Thing as a Renal Stem Cell?
August 29, 2009 at 10:45 am
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| | Is There Such a Thing as a Renal Stem Cell? J Am Soc Nephrol. 2009 Aug 27; Authors: Little MH, Bertram JF Increasing interest in the potential of adult stem cells in regenerative medicine has led to numerous studies focused on the identification of endogenous renal stem cells within the mature mammalian kidney. A variety of approaches have been taken to identify such cells, including physical location, cell surface marker expression, and functional properties. Proof of clonogenicity or renal potential remains questionable, and few such populations have been characterized in humans; however, recent evidence that even podocytes, a cell type with limited proliferative capacity under normal conditions, are constantly regenerated from a population within the Bowman's capsule has breathed new life into the quest for a renal stem cell. Here we examine whether current evidence is sufficient to conclude such a population does indeed exist or whether the jury is still out. We also ask which properties we would wish such a cell to possess to allow for repair of the diseased kidney. PMID: 19713310 [PubMed - as supplied by publisher] |
| Derivation and characterization of human embryonic germ cells: serum-free culture and differentiation potential.
August 29, 2009 at 10:45 am
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| | Derivation and characterization of human embryonic germ cells: serum-free culture and differentiation potential. Reprod Biomed Online. 2009 Aug;19(2):238-49 Authors: Hua J, Yu H, Liu S, Dou Z, Sun Y, Jing X, Yang C, Lei A, Wang H, Gao Z This study examined the effects of a chemically defined culture medium supplement, knock-out serum replacement (KSR), on the growth and differentiation of human embryonic germ cells (hEgc) and found that the efficiency of the initial establishment of hEGC lines in KSR medium was significantly higher than in fetal calf serum (FCS) medium. The percentage of undifferentiated hEGC colonies growing in KSR medium was significantly higher than in FCS-based medium (P < 0.05). The hEGC colonies showed typical mouse embryonic germ cell-like morphology. They showed normal and stable diploid karyotype and expressed alkaline phosphatase (AP), stage-specific embryonic antigens (SSEA) and other specific markers of pluripotent cells. In addition, hEGC could form simple and cystic embryoid bodies (EB) that consisted of various cell types including neural, epithelial and rhythmically beating cardiac cells, even sperm-like and oocyte-like cells. Tumour-like outgrowths were formed in nude mice and found to contain a variety of cell types, including uterine epithelium, adipocytes, squamous tissue and skin structures. In conclusion, an appropriate serum-free culture system has been developed for the establishment of hEGC lines. This may provide an in-vitro model to study differentiation and can be used as a potential source of therapy for infertility and regenerative medicine. PMID: 19712561 [PubMed - in process] |
| Isoproterenol-induced myocardial injury and diastolic dysfunction in mice: structural and functional correlates.
August 29, 2009 at 9:12 am
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| | Isoproterenol-induced myocardial injury and diastolic dysfunction in mice: structural and functional correlates. Comp Med. 2009 Aug;59(4):339-43 Authors: Brooks WW, Conrad CH The objective of this study was to determine whether a simple, noninvasive method involving administration of isoproterenol could be used to produce myocardial injury and cardiac dysfunction in the mouse heart with a low incidence of mortality. Adult Swiss-Webster mice were injected with isoproterenol (100 mg/kg SC) once daily for 5 d. Myocardial histology and left ventricular (LV) function were assessed 10 to 14 d after the last isoproterenol injection in 14 surviving isoproterenol-treated mice and 15 saline-treated control mice. Left ventricular systolic and diastolic pressures were evaluated in vitro by means of isovolumically contracting, perfused Langendorff preparations. Isoproterenol induced marked endocardial injury, associated with hypertrophy of surviving myocytes, and an increase in myocardial fibrosis (collagen types I and III according to picrosirius red microscopy). The hearts from isoproterenol-treated mice demonstrated decreased LV compliance, as evidenced by an upward shift in the diastolic pressure-volume relationship, with normal LV systolic function. Isoproterenol administration provides a simple, noninvasive means to induce endocardial injury and diastolic dysfunction without significant impairment of systolic function. This model has a low incidence of mortality and may be useful to assess the effects of gene or stem cell therapy on cardiac dysfunction without the potential confounding effects of invasive procedures. PMID: 19712573 [PubMed - in process] | | | 
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