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| The acellular matrix (ACM) for bladder tissue engineering: A quantitative magnetic resonance imaging study.
July 29, 2010 at 10:45 PM
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| | The acellular matrix (ACM) for bladder tissue engineering: A quantitative magnetic resonance imaging study. Magn Reson Med. 2010 Aug;64(2):341-8 Authors: Cheng HL, Loai Y, Beaumont M, Farhat WA Bladder acellular matrices (ACMs) derived from natural tissue are gaining increasing attention for their role in tissue engineering and regeneration. Unlike conventional scaffolds based on biodegradable polymers or gels, ACMs possess native biomechanical and many acquired biologic properties. Efforts to optimize ACM-based scaffolds are ongoing and would be greatly assisted by a noninvasive means to characterize scaffold properties and monitor interaction with cells. MRI is well suited to this role, but research with MRI for scaffold characterization has been limited. This study presents initial results from quantitative MRI measurements for bladder ACM characterization and investigates the effects of incorporating hyaluronic acid, a natural biomaterial useful in tissue-engineering and regeneration. Measured MR relaxation times (T(1), T(2)) and diffusion coefficient were consistent with increased water uptake and glycosaminoglycan content observed on biochemistry in hyaluronic acid ACMs. Multicomponent MRI provided greater specificity, with diffusion data showing an acellular environment and T(2) components distinguishing the separate effects of increased glycosaminoglycans and hydration. These results suggest that quantitative MRI may provide useful information on matrix composition and structure, which is valuable in guiding further development using bladder ACMs for organ regeneration and in strategies involving the use of hyaluronic acid. Magn Reson Med, 2010. (c) 2010 Wiley-Liss, Inc. PMID: 20665777 [PubMed - in process] | | |
| Hydroxyapatite/polyurethane scaffold incorporated with drug-loaded ethyl cellulose microspheres for bone regeneration.
July 29, 2010 at 10:45 PM
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| | Hydroxyapatite/polyurethane scaffold incorporated with drug-loaded ethyl cellulose microspheres for bone regeneration. J Biomed Mater Res B Appl Biomater. 2010 Jul 27; Authors: Liu H, Zhang L, Shi P, Zou Q, Zuo Y, Li Y The purpose of this study is to explore and develop biodegradable scaffold for bone regeneration or tissue engineering with the capacity of controlled drug delivery. Ceftazidime as a model drug was encapsulated in ethyl cellulose (EC) microspheres, which were subsequently incorporated in a hydroxyapatite/polyurethane (HA/PU) composite scaffold to generate an antibiotic drug delivery system. HA/PU scaffolds had an interconnected pore network with an average porosity of about 83%. The presence of microspheres in the composite scaffolds was confirmed by scanning electron microscopy. The drug-loaded EC microspheres were uniformly distributed in the HA/PU scaffold matrix and showed no significant effect on the pore structure of the scaffold. Incorporation of microspheres into scaffolds significantly reduced the initial burst release, and the system exhibited a sustained release of the model drug for up to 60 days. Moreover, the scaffold with drug-loaded microspheres was proved to be an effective drug delivery system with good cytocompatibility and antibacterial properties. The novel drug-loaded microsphere/scaffold composites developed in this study are promising to serve as vehicles for controlled drug delivery in bone regeneration or bone tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20665683 [PubMed - as supplied by publisher] | | |
| PLGA nanofiber-coated silk microfibrous scaffold for connective tissue engineering.
July 29, 2010 at 10:45 PM
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| | PLGA nanofiber-coated silk microfibrous scaffold for connective tissue engineering. J Biomed Mater Res B Appl Biomater. 2010 Jul 27; Authors: Sahoo S, Lok Toh S, Hong Goh JC A modified degumming technique, involving boiling in 0.25% Na(2)CO(3) with addition of 1% sodium dodecyl sulphate and intermittent ultrasonic agitation, was developed for knitted silk scaffolds. Sericin was efficiently removed, while mechanical and structural properties of native silk fibroin were preserved. Biocompatible and mechanically robust hybrid nano-microscaffolds were fabricated by coating these degummed silk scaffolds with an intervening adhesive layer of silk solution followed by electrospun poly-lactic-co-glycolic acid (PLGA) nanofibers. Cell proliferation on the hybrid silk scaffolds was improved by seeding cells on both surfaces of the flat scaffolds. Rolling up and continued culture of the cell-seeded hybrid scaffolds yielded cylindrical constructs that permitted cell proliferation, extracellular matrix deposition, and generated ligament/tendon graft analogs. Although PLGA-based hybrid scaffolds have earlier been proposed for dense connective tissue engineering, rapid biodegradation of PLGA was a drawback. In contrast, the underlying strong and slowly-degrading microfibrous silk scaffold used in this study ensured that the hybrid scaffold maintained adequate mechanical properties for longer periods, which is vital for continued support to the injured ligament/tendon throughout its healing period. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20665681 [PubMed - as supplied by publisher] | | |
| Apoptosis of mesenchymal stem cells induced by hydrogen peroxide concerns both endoplasmic reticulum stress and mitochondrial death pathway through regulation of caspases, p38 and JNK.
July 29, 2010 at 10:45 PM
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| | Apoptosis of mesenchymal stem cells induced by hydrogen peroxide concerns both endoplasmic reticulum stress and mitochondrial death pathway through regulation of caspases, p38 and JNK. J Cell Biochem. 2010 Jul 27; Authors: Wei H, Li Z, Hu S, Chen X, Cong X Poor survival of mesenchymal stem cells (MSCs) compromised the efficacy of stem cell therapy for myocardial infarction. The increase of exogenous reactive oxygen species (ROS) in infracted heart is one of the important factors that challenged the survival of donor MSCs. In the study we aimed to evaluate the effect of oxidative stress on the cell death of MSCs and investigate its mechanisms in order to help with the identification of new biological compounds to reduce donor cells damage. Apoptosis of MSCs were evaluated with Hoechst33342 staining and flow cytometry analysis. The mitochondrial membrane potential of MSCs was analyzed with JC-1 staining. Signaling pathways involved in H(2)O(2) induced apoptosis were analyzed with western blot. H(2)O(2) induced apoptosis of MSCs in a dose and time dependent manner. H(2)O(2) induced apoptosis of MSCs via both endoplasmic reticulum (ER) and mitochondrial pathways rather than extrinsic apoptosis pathway. H(2)O(2) caused transient rather than sustained activation of p38 and JNK with no effect on ERK1/2 pathway. P38 was involved in the regulation of early apoptosis of MSCs while JNK was involved in the late apoptosis. P38 directed both ER stress and mitochondria death pathway in the early apoptosis. In conclusion, Exogenous ROS was a major factor to induce apoptosis of MSCs. Both ER stress and mitochondria death pathway were involved in the apoptosis of MSCs. H(2)O(2) activated p38 that directed the above two pathways in the regulation of early apoptosis of MSCs while JNK was involved in the late apoptosis of MSCs. J. Cell. Physiol. (c) 2010 Wiley-Liss, Inc. PMID: 20665666 [PubMed - as supplied by publisher] | | |
| Chondrogenic potential of subpopulations of cells expressing mesenchymal stem cell markers derived from human synovial membranes.
July 29, 2010 at 10:45 PM
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| | Chondrogenic potential of subpopulations of cells expressing mesenchymal stem cell markers derived from human synovial membranes. J Cell Biochem. 2010 Jul 21; Authors: Arufe MC, Fuente AD, Fuentes I, de Toro FJ, Blanco FJ In this study we analyzed the chondrogenic potential of subpopulations of MSCs derived from human synovial membranes enriched for CD73, CD106 and CD271 markers.Subpopulations of human synovial membrane MSCs enriched for CD73, CD106 and CD271 markers were isolated using a cytometry sorter and characterized by flow cytometry for MSC markers. The expression of Sox9, Nanog and Runx2 genes by these cells was measured by reverse transcriptase-polymerase chain reaction. The chondrogenesis of each subpopulation was assessed by culturing the cells in a defined medium to produce spontaneous spheroid formation and differentiation towards chondrocyte-like cells. The examination of the spheroids by histological and immunohistochemical analyses for collagen type II (COL2), aggrecan, collagen type I (COL1), metalloprotease 13 (MMP13) and collagen type X (COLX) levels were performed to assess their chondrogenesis capacity. The adipogenesis and osteogenesis potential of each subpopulation was determined using commercial media; the resulting cells were stained with oil red O or red alizarin to test the degree of differentiation.The subpopulations had different profiles of cells positive for the MSC markers CD44, CD69, CD73, CD90 and CD105 and showed different expression levels of the genes Sox9, Nanog, Runx2 involved in chondrogenesis, undifferentiation and osteoblastogenesis, respectively. Immunohistochemical analysis demonstrated that COL1, COL2, COLX, MMP13 and aggrecan were expressed in the spheroids as soon as 14 days of culture. The CD271(+) subpopulation expressed the highest levels of COL2 staining compared to the other subpopulations. CD105 and Runx2 were shown by immunohistochemistry and genetic analysis to have significantly higher expression CD271+ subpopulation than the other subpopulations.Spheroids formed from CD271-enriched and CD73-enriched MSCs from normal human synovial membranes mimic the native cartilage extracellular matrix more closely than CD106(+) MSCs and are possible candidates for use in cartilage tissue engineering. Both cell types have potential for promoting the differentiation of MSCs into chondrocytes, presenting new possibilities for achieving intrinsic cartilage repair. (c) 2010 Wiley-Liss, Inc. PMID: 20665538 [PubMed - as supplied by publisher] | | |
| Modification of the chiral selectivity of d-glucose oxidase and l-lactate oxidase in a collagen matrix.
July 29, 2010 at 10:45 PM
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| | Modification of the chiral selectivity of d-glucose oxidase and l-lactate oxidase in a collagen matrix. Phys Chem Chem Phys. 2010 Jul 22; Authors: Kataky R, Zawawi RM A chiral, biocompatible, conducting material comprising collagen I, silica gel and ferrocene was found to modify and invert, the chiral selectivity of d-glucose oxidase and l-lactate oxidase. This result may have implications as collagen matrices are widely used in drug delivery, biosensing and tissue engineering. Investigations were carried out using electrochemical methods, FTIR spectroscopy and circular dichroism. PMID: 20664851 [PubMed - as supplied by publisher] | | |
| Stimuli-responsive microwells for formation and retrieval of cell aggregates.
July 29, 2010 at 10:45 PM
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| | Stimuli-responsive microwells for formation and retrieval of cell aggregates. Lab Chip. 2010 Jul 27; Authors: Tekin H, Anaya M, Brigham MD, Nauman C, Langer R, Khademhosseini A Generating cell aggregates is beneficial for various applications ranging from biotechnology to regenerative therapies. Previously, poly(ethylene glycol) (PEG) microwells have been demonstrated as a potentially useful method for generating controlled-size cell aggregates. In addition to controlling cell aggregate size and homogeneity, the ability to confine cell aggregates on glass adhesive substrates and subsequently retrieve aggregates from microwells for further experimentation and analysis could be beneficial for various applications. However, it is often difficult to retrieve cell aggregates from these microwells without the use of digestive enzymes. This study describes the stable formation of cell aggregates in responsive microwells with adhesive substrates and their further retrieval in a temperature dependent manner by exploiting the stimuli responsiveness of these microwells. The responsive polymer structure of the arrays can be used to thermally regulate the microwell diameters causing a mechanical force on the aggregates, subsequently facilitating the retrieval of cell aggregates from the microwells with high efficiency compared to PEG arrays. This approach can be potentially integrated into high-throughput systems and may become a versatile tool for various applications that require aggregate formation and experimentation, such as tissue engineering, drug discovery, and stem cell biology. PMID: 20664846 [PubMed - as supplied by publisher] | | |
| Modulation of rabbit corneal epithelial cells fate using embryonic stem cell extract.
July 29, 2010 at 10:45 PM
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| | Modulation of rabbit corneal epithelial cells fate using embryonic stem cell extract. Mol Vis. 2010;16:1154-61 Authors: Zhan W, Liu Z, Liu Y, Ke Q, Ding Y, Lu X, Wang Z PURPOSE: To develop a new culture system to cultivate differentiated autologous cells in vitro for cell therapy and tissue engineering. METHODS: After incubation in murine embryonic stem cell (ESC) extract for 1 h, streptolysin-O (SLO) permeabilized cells were resealed with CaCl(2) and continually cultured for weeks. The morphological study was analyzed by light microscopy. Isolated colonies were selected and expanded to establish cell lines. Octamer-4 (Oct-4), stage-specific embryonic antigen-1 (SSEA-1), transformation-related protein 63 (p63), ATP-binding cassette subfamily G, member 2 (ABCG2), and cytokeratin3 (K3) were detected by indirect immunofluorescent staining. Oct-4, K3, and p63 were also detected by RT-PCR analysis. To examine the stemness characteristics of the induced cells, both alkaline phosphatase (AKP) staining and tumorigenicity detection were performed, respectively. RESULTS: Reprogramming was induced in corneal epithelial cells. The reprogrammed cells showed characteristics similar to ESCs in the early weeks, including colony formation, positive AKP staining, and multi-potential differentiation in vivo. Oct-4 and SSEA1 protein expression was upregulated. However, these changes were not persistent or stable. With the passage of time, the colonies became flat. The ESC markers were downregulated, while epithelial cell related proteins gradually increased. CONCLUSIONS: Less terminal differentiated rabbit corneal epithelial cells could be induced to a more pluripotent state with embryonic stem cell extract (ESC-E). These cells have the potential to return to the beginning of their own lineage and obtain the ability of long-term growth. Our fi ndings indicate that this culture system can generate low-immunogenic autologous cells for use in regenerative medicine. PMID: 20664691 [PubMed - in process] | | |
| Cellular Antioxidant Levels Influence Muscle Stem Cell Therapy.
July 29, 2010 at 10:45 PM
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| | Cellular Antioxidant Levels Influence Muscle Stem Cell Therapy. Mol Ther. 2010 Jul 27; Authors: Drowley L, Okada M, Beckman S, Vella J, Keller B, Tobita K, Huard J Although cellular transplantation has been shown to promote improvements in cardiac function following injury, poor cell survival following transplantation continues to limit the efficacy of this therapy. We have previously observed that transplantation of muscle-derived stem cells (MDSCs) improves cardiac function in an acute murine model of myocardial infarction to a greater extent than myoblasts. This improved regenerative capacity of MDSCs is linked to their increased level of antioxidants such as glutathione (GSH) and superoxide dismutase. In the current study, we demonstrated the pivotal role of antioxidant levels on MDSCs survival and cardiac functional recovery by either reducing the antioxidant levels with diethyl maleate or increasing antioxidant levels with N-acetylcysteine (NAC). Both the anti- and pro-oxidant treatments dramatically influenced the survival of the MDSCs in vitro. When NAC-treated MDSCs were transplanted into infarcted myocardium, we observed significantly improved cardiac function, decreased scar tissue formation, and increased numbers of CD31(+) endothelial cell structures, compared to the injection of untreated and diethyl maleate-treated cells. These results indicate that elevating the levels of antioxidants in MDSCs with NAC can significantly influence their tissue regeneration capacity. PMID: 20664528 [PubMed - as supplied by publisher] | | |
| Regulatory mechanisms in vascular calcification.
July 29, 2010 at 10:45 PM
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| | Regulatory mechanisms in vascular calcification. Nat Rev Cardiol. 2010 Jul 27; Authors: Sage AP, Tintut Y, Demer LL In the past decade, the prevalence, significance, and regulatory mechanisms of vascular calcification have gained increasing recognition. Over a century ago, pathologists recognized atherosclerotic calcification as a form of extraskeletal ossification. Studies are now identifying the mechanism of this remarkable process as a recapitulation of embryonic endochondral and membranous ossification through phenotypic plasticity of vascular cells that function as adult mesenchymal stem cells. These embryonic developmental programs, involving bone morphogenetic proteins and potent osteochondrogenic transcription factors, are triggered and modulated by a variety of inflammatory, metabolic, and genetic disorders, particularly hyperlipidemia, chronic kidney disease, diabetes, hyperparathyroidism, and osteoporosis. They are also triggered by loss of powerful inhibitors, such as fetuin A, matrix Gla protein, and pyrophosphate, which ordinarily restrict biomineralization to skeletal bone. Teleologically, soft-tissue calcification might serve to create a wall of bone to sequester noxious foci such as chronic infections, parasites, and foreign bodies. This Review focuses on atherosclerotic and medial calcification. The capacity of the vasculature to produce mineral in culture and to produce de novo, vascularized, trabecular bone and cartilage tissue, even in patients with osteoporosis, should intrigue investigators in tissue engineering and regenerative biology. PMID: 20664518 [PubMed - as supplied by publisher] | | |
| Modified Gellan Gum hydrogels with tunable physical and mechanical properties.
July 29, 2010 at 10:45 PM
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| | Modified Gellan Gum hydrogels with tunable physical and mechanical properties. Biomaterials. 2010 Jul 19; Authors: Coutinho DF, Sant SV, Shin H, Oliveira JT, Gomes ME, Neves NM, Khademhosseini A, Reis RL Gellan Gum (GG) has been recently proposed for tissue engineering applications. GG hydrogels are produced by physical crosslinking methods induced by temperature variation or by the presence of divalent cations. However, physical crosslinking methods may yield hydrogels that become weaker in physiological conditions due to the exchange of divalent cations by monovalent ones. Hence, this work presents a new class of GG hydrogels crosslinkable by both physical and chemical mechanisms. Methacrylate groups were incorporated in the GG chain, leading to the production of a methacrylated Gellan Gum (MeGG) hydrogel with highly tunable physical and mechanical properties. The chemical modification was confirmed by proton nuclear magnetic resonance ((1)H NMR) and Fourier transform infrared spectroscopy (FTIR-ATR). The mechanical properties of the developed hydrogel networks, with Young's modulus values between 0.15 and 148 kPa, showed to be tuned by the different crosslinking mechanisms used. The in vitro swelling kinetics and hydrolytic degradation rate were dependent on the crosslinking mechanisms used to form the hydrogels. Three-dimensional (3D) encapsulation of NIH-3T3 fibroblast cells in MeGG networks demonstrated in vitro biocompatibility confirmed by high cell survival. Given the highly tunable mechanical and degradation properties of MeGG, it may be applicable for a wide range of tissue engineering approaches. PMID: 20663552 [PubMed - as supplied by publisher] | | |
| X-Ray Imaging of Poly(Ethylene Glycol) Hydrogels Without Contrast Agents.
July 29, 2010 at 10:45 PM
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| | X-Ray Imaging of Poly(Ethylene Glycol) Hydrogels Without Contrast Agents. Tissue Eng Part C Methods. 2010 Jul 27; Authors: Brey EM, Appel A, Chiu YC, Zhong Z, Cheng MH, Engel H, Anastasio MA Hydrogels have shown promise for a number of tissue engineering applications. However, their high water content results in little or no image contrast when using conventional X-ray imaging techniques. X-ray imaging techniques based on phase-contrast have shown promise for biomedical application due to their ability to provide information about the X-ray refraction properties of samples. Nonporous and porous poly(ethylene glycol) hydrogels were synthesized and imaged using a synchrotron light source employing a silicon analyzer crystal and an X-ray energy of 40-keV. Data were acquired at 21 angular analyzer positions spanning the range of -5 to 5 murad. Images that depict the projected X-ray absorption, refraction, and ultra-small-angle scatter (USAXS) properties of the hydrogels were reconstructed from the measurement data. The poly(ethylene glycol) hydrogels could be discerned from surrounding water and soft tissue in the refraction image but not the absorption or USAXS images. In addition, the refraction images of the porous hydrogels have a speckle pattern resulting in increased image texture in comparison to nonporous hydrogels. To our knowledge, this is the first study to show that X-ray phase-contrast imaging techniques can identify and provide detail on hydrogel structure without the addition of contrast agents. PMID: 20662738 [PubMed - as supplied by publisher] | | |
| Comparative study of stemness characteristics of mesenchymal cells from bone marrow of children and adults.
July 29, 2010 at 10:45 PM
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| | Comparative study of stemness characteristics of mesenchymal cells from bone marrow of children and adults. Cytotherapy. 2010 Jul 22; Authors: Choumerianou DM, Martimianaki G, Stiakaki E, Kalmanti L, Kalmanti M, Dimitriou H Abstract Background aims. Age-related changes that could affect the biologic features of mesenchymal stromal cells (MSC), such as a decrease in proliferation and osteoblast differentiation capacity and an increase of senescence markers and apoptosis, have been reported recently. The aim of this study was the evaluation of age-related characteristics and the correlation of age with the functional properties of MSC. Methods. The doubling time (DT), colony-forming unit-fibroblast (CFU-F) colonies and surface antigen expression of MSC isolated from bone marrow (BM) of children (C-MSC) were compared with those from adults (A-MSC). The expression of Oct-4 and Nanog transcripts and the relative telomere length were evaluated in both groups. Results. DT values were lower in C-MSC compared with A-MSC, and a higher CFU-F count was observed in children. However, the expression of Oct-4 and Nanog did not differ between C-MSC and A-MSC and was not correlated with the proliferative capacity. The telomere length was significantly higher in C-MSC compared with A-MSC. Conclusions. These data suggest that children's BM-derived MSC could be a more advantageous source of these cells for tissue engineering and cell therapy. PMID: 20662612 [PubMed - as supplied by publisher] | | |
| Growth factor and cytokine expression of human mesenchymal stromal cells is not altered in an in vitro model of tissue damage.
July 29, 2010 at 10:45 PM
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| | Growth factor and cytokine expression of human mesenchymal stromal cells is not altered in an in vitro model of tissue damage. Cytotherapy. 2010 Jul 22; Authors: Montzka K, Führmann T, Müller-Ehmsen J, Wöltje M, Brook GA Abstract Background aims. The beneficial effect of human (h) mesenchymal stromal cell (MSC) transplantation in a variety of cell-based intervention strategies is widely believed to be because of paracrine mechanisms. The modification of hMSC cytokine and growth-factor expression patterns were studied following exposure to lipopolysaccharide (LPS) and tissue homogenates (representing tissue debris) from normal and pathologic tissues. Methods. Human bone marrow-derived MSC were stimulated with LPS or exposed to homogenate from normal or pathologic rat spinal cord or heart. The expression profiles of a number of cytokines and growth factors were investigated using quantitative reverse transcription (RT)-polymerase chain reaction (PCR) with human-specific primers. The effects of tissue homogenates on hMSC proliferation and migratory behavior were also investigated. Results. Stimulation of hMSC with LPS resulted in an up-regulation of interleukin (IL)-1beta, IL-6 and IL-8. However, the pattern of up-regulation varied between donor samples. Furthermore, LPS treatment resulted in a donor-dependent alteration of growth factor expression. Induction of a shift in expression pattern was not observed following exposure to homogenates from either normal or pathologic tissues. Tissue homogenates did stimulate cell proliferation, but not migration. Conclusions. The hMSC expression pattern is apparently stable, even when cells are confronted by debris from different tissue types. However, treatment of hMSC with LPS is able to change the expression of cytokines and growth factors in a donor-dependent manner that may enhance their potential use in regenerative medicine. PMID: 20662610 [PubMed - as supplied by publisher] | | |
| Impaired bladder function in aging male rats.
July 29, 2010 at 10:45 PM
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| | Impaired bladder function in aging male rats. J Urol. 2010 Jul;184(1):378-85 Authors: Zhao W, Aboushwareb T, Turner C, Mathis C, Bennett C, Sonntag WE, Andersson KE, Christ G PURPOSE: The prevalence of bladder dysfunctions increases with age. In humans it is difficult to separate changes related to exogenous factors from those directly related to the aging process. Some confounding variables can be avoided by studying age related changes in an animal model. We evaluated the impact of age on bladder function in vivo and in vitro, and characterized the corresponding morphological changes. MATERIALS AND METHODS: Young (4 to 6 months old) and old (older than 28 to 30 months) male Fischer/Brown Norway rats were used in the study. Cystometric studies were done in conscious, freely moving rats. After cystometry tissue strips from the bladder body were used in in vitro studies of muscarinic receptor activation and electrical field stimulation, and histological examination. RESULTS: Old rats had higher bladder weight than young rats but the bladder-to-body weight ratio did not change. We noted significant age related differences in 8 of 10 cystometric parameters. Old rats had increased bladder capacity, post-void residual volume, micturition volume and frequency, baseline and intermicturition pressure, and spontaneous activity but decreased micturition pressure. Bladder strip responses to carbachol and electrical field stimulation were significantly lower in old than in young rats. Histological examination revealed urothelial thinning, lower muscle mass and higher collagen content in the bladders of old vs young rats. CONCLUSIONS: Physiological aging alters bladder function in male rats even when external factors remain constant. Thus, in old rats bladder capacity, post-void residual urine and spontaneous activity are higher, and responses to muscarinic receptor stimulation and electrical field stimulation are lower than in young rats. Such changes correspond to findings in aging human bladders, supporting the view that the Fischer/Brown Norway rat is a useful model in which to study age related bladder function changes. PMID: 20488483 [PubMed - indexed for MEDLINE] | | |
| A novel biomimetic composite scaffold hybridized with mesenchymal stem cells in repair of rat bone defects models.
July 29, 2010 at 5:45 PM
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| | A novel biomimetic composite scaffold hybridized with mesenchymal stem cells in repair of rat bone defects models. J Biomed Mater Res A. 2010 Jul 27; Authors: Xu C, Su P, Wang Y, Chen X, Meng Y, Liu C, Yu X, Yang X, Yu W, Zhang X, Xiang AP In this study, the in vivo bone-regenerative potential of a novel bioactive glass-collagen-hyaluronic acid-Phosphatidylserine (BG-COL-HYA-PS) composite scaffold hybridized with mesenchymal stem cells (MSCs) was investigated in a rat bone defect model. HrGFP-labeled MSCs were cultured for 2 weeks on the BG-COL-HYA-PS scaffold before implantation into the defect. A cell-free scaffold and an untreated defect were used as controls. The regeneration process was evaluated by histology, X-ray, and mechanical rigidity experiments at different time points post-implantation. The results revealed that BG-COL-HYA-PS scaffold exhibited a low inflammatory response and foreign body response within 3 weeks. At week 6, those responses disappeared following the resorption of scaffolds and the formation of new bone. Compared with the pure scaffold or empty group, the introduction of MSCs into the porous scaffold dramatically enhanced the efficiency of the new bone formation and biomechanical property of the femur. In addition, the transplanted MSCs could survive for up to 3 weeks or longer. The results demonstrated that the BG-COL-HYA-PS scaffold was biocompatible and osteoconductive and the transplanted MSCs with the scaffold enhanced the healing of the bone defect. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20665678 [PubMed - as supplied by publisher] | | |
| A cloned pig model for examining atherosclerosis induced by high fat, high cholesterol diets.
July 29, 2010 at 5:45 PM
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| | A cloned pig model for examining atherosclerosis induced by high fat, high cholesterol diets. Anim Biotechnol. 2010 Jul;21(3):179-87 Authors: Jensen TW, Mazur MJ, Pettigew JE, Perez-Mendoza VG, Zachary J, Schook LB The pig is a recognized model for the onset of coronary heart disease and heart attacks. Previous studies have shown that serum cholesterol levels in the pig can be elevated using a high fat, high cholesterol (HFHC) diet. What has been lacking is a genetically defined model corresponding to human ApoE4 susceptibility that can be linked to diets capable of inducing atherosclerosis. This study used a cloned pig model to examine the impact of cholesterol levels with the development of aorta fatty deposits leading to atherosclerosis. Diets were formulated using vegetable sources of protein to provide similar intakes of metabolizable energy, calcium, phosphorous and principal amino acids in both control and HFHC groups. After 60 days, the HFHC group demonstrated a 40-fold increase in aortic fatty streak lesion area combined with 6- and 11-fold increases in total and LDL cholesterol, respectively, over control diet fed cloned pigs. Previous studies have suffered from either imbalanced total caloric intake, an overall imbalance in the nutrition of the control versus HFHC groups or genetic heterogeneity when evaluating dietary constraints related to atherosclerosis. This study demonstrated that cloned, genetically-defined ApoE4 pigs provided balanced nutrition diets provide an experimental system ideally suited to examining atherosclerosis and the onset of coronary heart disease. PMID: 20665290 [PubMed - in process] | | | | 
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