| Hydroxyapatite scaffolds processed using a TBA-based freeze-gel casting/polymer sponge technique.
January 26, 2010 at 7:22 AM
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| | Hydroxyapatite scaffolds processed using a TBA-based freeze-gel casting/polymer sponge technique. J Mater Sci Mater Med. 2010 Jan 23; Authors: Yang TY, Lee JM, Yoon SY, Park HC A novel freeze-gel casting/polymer sponge technique has been introduced to fabricate porous hydroxyapatite scaffolds with controlled "designer" pore structures and improved compressive strength for bone tissue engineering applications. Tertiary-butyl alcohol (TBA) was used as a solvent in this work. The merits of each production process, freeze casting, gel casting, and polymer sponge route were characterized by the sintered microstructure and mechanical strength. A reticulated structure with large pore size of 180-360 mum, which formed on burn-out of polyurethane foam, consisted of the strut with highly interconnected, unidirectional, long pore channels (~4.5 mum in dia.) by evaporation of frozen TBA produced in freeze casting together with the dense inner walls with a few, isolated fine pores (<2 mum) by gel casting. The sintered porosity and pore size generally behaved in an opposite manner to the solid loading, i.e., a high solid loading gave low porosity a! nd small pore size, and a thickening of the strut cross section, thus leading to higher compressive strengths. PMID: 20099009 [PubMed - as supplied by publisher] | | |
| Comparison of Data From the Rostock Cornea Module of the Heidelberg Retina Tomograph, the Oculus Pentacam, and the Endothelial Cell Microscope.
January 26, 2010 at 7:22 AM
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| | Comparison of Data From the Rostock Cornea Module of the Heidelberg Retina Tomograph, the Oculus Pentacam, and the Endothelial Cell Microscope. Cornea. 2010 Jan 21; Authors: Rieth S, Engel F, Bühner E, Uhlmann S, Wiedemann P, Foja C PURPOSE:: The aim of this study was to validate data arising from the Rostock Cornea Module (RCM) of the Heidelberg Retina Tomograph. Morphological parameters of the cornea were analyzed according to their dependency on patient's age. METHODS:: RCM measurements of 60 healthy eyes within 2 different age groups (group 1 <35 years, group 2 >50 years) were compared with the corneal thickness determined by the Oculus Pentacam and the endothelial cell density measured by the Tomey endothelial microscope, EM-2000. RESULTS:: The mean corneal thickness measured with the Heidelberg Retina Tomograph/RCM was 517 +/- 31 mum and 542 +/- 30 mum with the Oculus Pentacam (correlation coefficient, R = 0.78). Group 1 showed a corneal thickness of 509 +/- 24mum with the RCM and 531 +/- 27mum with the Pentacam. In group 2, the corneal thickness was 525 +/- 34 mum and 553 +/- 29 mum, respectively. A significant increase in corneal thickness for older patients could be shown. The ! differences between the methods and the age groups were statistically significant (P < 0.0001). The average endothelial cell density measured with the RCM was 2779 +/- 472 cells per square millimeter. Between the age groups and the methods (RCM and endothelial microscope), no statistically significant differences could be found. Cell densities for the epithelial cell layers and keratocytes showed no significant correlation with age and sex of the patients. CONCLUSIONS:: The RCM provides a reliable procedure for the evaluation of all corneal layers including morphological parameters. Endothelial cell densities either determined with the RCM or the EM-2000 are generally comparable to each other and showed no significant differences. It is suggested that lower corneal thickness measurements of the RCM can be caused by pressure during examination. An increased corneal thickness in the older group could be determined with the RCM and the Oculus Pentacam. PMID: 20098314 [PubMed - as supplied by publisher] | | |
| Functionalization of multi-walled carbon nanotubes via surface unpaired electrons.
January 26, 2010 at 7:22 AM
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| | Functionalization of multi-walled carbon nanotubes via surface unpaired electrons. Nanotechnology. 2010 Jan 25;21(8):85706 Authors: Zhang H, Guo H, Deng X, Gu P, Chen Z, Jiao Z The unpaired electrons on multi-walled carbon nanotubes (MWNTs) treated by nitric-sulfuric mixed acid were detected and characterized by electron spin resonance (ESR). Through reacting with these unpaired electrons, highly soluble acrylamide-grafted MWNTs were successfully prepared and characterized by ESR, FT-IR, UV-vis and atomic force microscopy (AFM), etc. The results indicate that MWNTs could generate more unpaired electrons with longer mixed-acid treatment time and could be well functionalized by acrylamide. By AFM analysis, a 'net' structure was formed on MWNTs after grafting with acrylamide. This new method has some obvious advantages of mild reaction conditions and convenient operation, etc. Furthermore, the grafting of MWNTs may have great potential for biomedical applications in drug delivery and regenerative medicine owing to their excellent networks. PMID: 20097979 [PubMed - as supplied by publisher] | | |
| Hyaluronan mixed esters of butyric and retinoic acid affording myocardial survival and repair without stem cell transplantation.
January 26, 2010 at 7:22 AM
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| | Hyaluronan mixed esters of butyric and retinoic acid affording myocardial survival and repair without stem cell transplantation. J Biol Chem. 2010 Jan 22; Authors: Lionetti V, Cantoni S, Cavallini C, Bianchi F, Valente S, Frascari I, Olivi E, Aquaro GD, Bonavita F, Scarlata I, Maioli M, Vaccari V, Tassinari R, Bartoli A, Recchia FA, Pasquinelli G, Ventura C Possible cardiac repair by adult stem cell transplantation is currently hampered by poor cell viability and delivery efficiency, uncertain differentiating fate in vivo, the needs for ex vivo cell expansion, and consequent delay in transplantation after the onset of heart attack. By the aid of Magnetic Resonance Imaging, Positron Emission Tomography Imaging, and immunohistochemistry, we show that injection of a hyaluronan mixed ester of butyric and retinoic acid (HBR) into infarcted rat hearts afforded substantial cardiovascular repair and recover of myocardial performance. HBR restored cardiac 18F-FDG uptake, increased capillary density and led to the recruitment of endogenous Stro-1-positive stem cells. TUNEL assay demonstrated that HBR-treated hearts exhibited a decrease in the number of apoptotic cardiomyocytes. In isolated rat cardiomyocytes and Stro-1 stem cells HBR enhanced the transcription of VEGF, HGF, KDR, Akt, and Pim-1. HBR also increased the secretion! of VEGF and HGF, suggesting that the mixed ester may have recruited both myocardial and Stro-1 cells into a pro-angiogenic paracrine circuitry of cardiac repair. An increase in capillarogenesis was induced in vitro with medium obtained from HBR-exposed cells. In the infarcted heart tissue, HBR injection increased histone H4 acetylation, as compared with non-injected samples. Acetyl-H4 immunoreactivity was also higher in rat cardiomyocytes and Stro-1 cells exposed to HBR, compared to untreated cells. In conclusion, efficient amelioration of cardiac function can be afforded by HBR without the need of stem cell transplantation or vector-mediated gene delivery. The current findings may pave new perspectives in regenerative medicine. PMID: 20097747 [PubMed - as supplied by publisher] | | |
| Validation of a High Throughput Methodology to Assess the Effects of Biomaterials on Dendritic Cell Phenotype.
January 26, 2010 at 7:22 AM
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| | Validation of a High Throughput Methodology to Assess the Effects of Biomaterials on Dendritic Cell Phenotype. Acta Biomater. 2010 Jan 21; Authors: Kou PM, Babensee JE A variety of combination products composed of biomaterials and biologics have been developed for tissue regeneration or vaccine delivery. The host immune response to the immunogenic biological components in such products may be modulated by the biomaterial component. Distinct biomaterials have been shown to differentially affect the maturation of dendritic cells (DCs). DCs are professional antigen-presenting cells (APCs) that bridge innate and adaptive immunity and play a central role in inducing immunity or initiating immune tolerance. However, the biomaterials systems used to study DC response thus far have been insufficient to draw a clear conclusion as to which biomaterial properties are the key to controlling DC phenotype. In this study, we developed a 96-well filter plate-based high throughput (HTP) methodology to assess DC maturation upon biomaterial treatment. Equivalent biomaterial effects on DC phenotype were measured using the conventional flow cytometr! ic and filter plate method, which validated the HTP methodology. This methodology will be used to screen a large number of biomaterials simultaneously and to draw correlations between material properties and DC phenotype, thereby providing biomaterial design criteria and immunomodulatory strategies for both tissue engineering and vaccine delivery applications. PMID: 20097314 [PubMed - as supplied by publisher] | | |
| Human Amniotic Fluid as a Potential New Source of Organ Specific Precursor Cells for Future Regenerative Medicine Applications.
January 26, 2010 at 7:22 AM
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| | Human Amniotic Fluid as a Potential New Source of Organ Specific Precursor Cells for Future Regenerative Medicine Applications. J Urol. 2010 Jan 21; Authors: Da Sacco S, Sedrakyan S, Boldrin F, Giuliani S, Parnigotto P, Habibian R, Warburton D, De Filippo RE, Perin L PURPOSE: Human amniotic fluid contains multiple cell types, including pluripotent and committed progenitor cells, and fully differentiated cells. We characterized various cell populations in amniotic fluid. MATERIALS AND METHODS: Optimum culture techniques for multiple cell line passages with minimal morphological change were established. Cell line analysis and characterization were done with reverse transcriptase and real-time polymerase chain reaction. Immunoseparation was done to distinguish native progenitor cell lines and their various subpopulations. RESULTS: Endodermal and mesodermal marker expression was greatest in samples of early gestational age while ectodermal markers showed a constant rate across all samples. Pluripotent and mesenchymal cells were always present but hematopoietic cell markers were expressed only in older samples. Specific markers for lung, kidney, liver and heart progenitor cells were increasingly expressed after 18 weeks of gestatio! n. We specifically focused on a CD24+OB-cadherin+ population that could identify uninduced metanephric mesenchyma-like cells, which in vivo are nephron precursors. The CD24+OB-cadherin+ cell line was isolated and subjected to further immunoseparation to select 5 distinct amniotic fluid kidney progenitor cell subpopulations based on E-cadherin, podocalyxin, nephrin, TRKA and PDGFRA expression, respectively. CONCLUSIONS: These subpopulations may represent different precursor cell lineages committed to specific renal cell fates. Committed progenitor cells in amniotic fluid may provide an important and novel resource of useful cells for regenerative medicine purposes. PMID: 20096867 [PubMed - as supplied by publisher] | | |
| Reduced versican cleavage due to Adamts9 haploinsufficiency is associated with cardiac and aortic anomalies.
January 26, 2010 at 7:22 AM
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| | Reduced versican cleavage due to Adamts9 haploinsufficiency is associated with cardiac and aortic anomalies. Matrix Biol. 2010 Jan 20; Authors: Kern CB, Wessels A, McGarity J, Dixon LJ, Alston E, Argraves WS, Geeting D, Nelson CM, Menick DR, Ape SS Here, we demonstrate that ADAMTS9, a highly conserved versican-degrading protease, is required for correct cardiovascular development and adult homeostasis. Analysis of Adamts9(+/LacZ) heterozygous adult mice revealed anomalies in the aortic wall, valvulosinus and valve leaflets. Abnormal myocardial projections and 'spongy' myocardium consistent with non-compaction of the left ventricle were also found in Adamts9(+/LacZ) mice. During development, Adamts9 was expressed in derivatives of the Secondary Heart Field, vascular smooth muscle cells (VSMC) in the arterial wall, mesenchymal cells of the valves, and non-myocardial cells of the ventricular myocardium but expression also continued in the adult heart and ascending aorta. Thus, the adult cardiovascular anomalies found in Adamts9(+/LacZ) hearts could result from subtle developmental alterations in extracellular matrix remodeling or defects in adult homeostasis. The valvular and aortic anomalies of Adamts9(+/LacZ)! hearts were associated with accumulation of versican and a decrease in cleaved versican relative to WT littermates. These data suggest a potentially important role for ADAMTS9 cleavage of versican, or other, as yet undefined substrates in development and allostasis of cardiovascular extracellular matrix. In addition these studies identify ADAMTS9 as a potential candidate gene for congenital cardiac anomalies. Mouse models of ADAMTS9 deficiency may be useful to study myxomatous valve degeneration. PMID: 20096780 [PubMed - as supplied by publisher] | | |
| In situ collagen polymerization of layered cell-seeded electrospun scaffolds for bone tissue engineering applications.
January 26, 2010 at 7:22 AM
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| | In situ collagen polymerization of layered cell-seeded electrospun scaffolds for bone tissue engineering applications. Tissue Eng Part C Methods. 2010 Jan 22; Authors: McCullen S, Miller P, Gittard S, Pourdeyhimi B, Gorga R, Narayan R, Loboa E Electrospun scaffolds have been studied extensively for their potential use in bone tissue engineering applications. However, inherent issues with the electrospinning approach limit the thickness of these scaffolds and constrain their use for repair of critical-size bone defects. One method to increase overall scaffold thickness is to bond multiple electrospun scaffolds together with a biocompatible gel. The objective of this study was to determine if multiple hASC-seeded electrospun, nanofibrous scaffolds could be layered via in situ collagen assembly and whether the addition of laser ablated micron-sized pores within the electrospun scaffold layers was beneficial to the bonding process. Pores were created by a laser ablation technique. We hypothesized that the addition of micron-sized pores within the electrospun scaffolds would encourage collagen integration between scaffold layers, and promote osteogenic differentiation of human adipose-derived stem cells (hAS! Cs) seeded within the layered electrospun scaffolds. To evaluate the benefit of assembled scaffolds with and without engineered pores, hASCs were seeded on individual electrospun scaffolds, hASC-seeded scaffolds were bonded with type I collagen, and the assembled ~3 mm thick constructs were cultured for three weeks to examine their potential as bone tissue engineering scaffolds. Assembled electrospun scaffolds/collagen gel constructs using electrospun scaffolds with pores resulted in enhanced hASC viability, proliferation, and mineralization of the scaffolds after three weeks in vitro compared to constructs using electrsopun scaffolds without pores. Scanning electron microscopy and histological examination revealed that the assembled constructs that included laser ablated electrospun scaffolds were able to maintain a contracted structure and not delaminate, unlike assembled constructs containing non-ablated electrospun scaffolds. This is the first study to show that the int! roduction of engineered pores in electrospun scaffolds assists! with mu lti-layered scaffold integration resulting in thick constructs potentially suitable for use as scaffolds for bone tissue engineering or repair of critical bone defects. PMID: 20095827 [PubMed - as supplied by publisher] | | |
| Influence of intracoronary injections of bone-marrow-derived mononuclear cells on large myocardial infarction outcome: quantum of initial necrosis is the key.
January 26, 2010 at 7:22 AM
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| | Influence of intracoronary injections of bone-marrow-derived mononuclear cells on large myocardial infarction outcome: quantum of initial necrosis is the key. Vojnosanit Pregl. 2009 Dec;66(12):998-1004 Authors: Obradović S, Balint B, Romanovic R, Trifunović Z, Rusović S, Baskot B, Dopudja M, Trifunović G, Rafajlovski S, Jung R, Gligić B BACKGROUND/AIM: Autologous bone-marrow-derived intra= coronary injection of mononuclear cells (MNC) modestly improved left ventricular ejection fraction (LVEF) in the selected patients after acute ST elevation myocardial infarction (STEMI). Major determinants of stem cell therapy outcome in the subacute phase of STEMI still remain unknown. Therefore, the aim of this study was to determine modifying factors for the outcome of stem cell therapy after STEMI. METHODS: Eighteen patients in the stem cell therapy group and 24 patients in the control group with the successfully reperfused first large STEMI (LVEF < or = 40%) were enrolled in the study. The stem cell group was submitted to autologous bone-marrow-derived MNC injection between 7-12 days after MI. Left ventricular ejection fraction and infarction size at baseline and after 4 months were determined by echocardiography and scintigraphy examination. Age, pain onset to reperfusion time, admission glycemia, maxi! mum lactate dehydrogenase (LDH) activity and C-reactive protein level, baseline LVEF and infarction size, and the number of MNC injected were compared between patients with and without significant improvement of LVEF and decrease of myocardial infarct size after 4 months. RESULTS: In the stem cell group, patients with the improvement of LVEF for more than 5.1% had significantly lower levels of LDH than patients without such improvement (1689 +/- 139 vs 2133 +/- 215 IU/L, p < 0.001) and lower baseline infarction size on scintigraphy (26.7 +/- 5.2 vs 34.9 +/- 3.7%, p < 0.001). Such dependence was not found in the control group. CONCLUSION: In the patients with first large STEMI intracoronary injection of autologous bone-marrow-derived MNC leads to the significant decrease of myocardial infarction size but not the significant improvement of LVEF after four months. Higher serum LDH levels after STEMI and very large baseline infarction size are predictors of failure of ste! m cell therapy in our group of STEMI patients. PMID: 20095521 [PubMed - in process] | | |
| [The three-dimensional culture of adult mesenchymal stem cells for intervertebral disc tissue engineering]
January 26, 2010 at 7:22 AM
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| | [The three-dimensional culture of adult mesenchymal stem cells for intervertebral disc tissue engineering] Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2009 Dec;26(6):1300-5 Authors: Feng G, Liu H, Deng L, Chen X, Zhao X, Liang T, Li X Intervertebral disc (IVD) degeneration is one of the major causes of low back pain. As current clinical treatments are aimed at restoring biomechanical function and providing symptomatic relief, the methods focused on biological repair have aroused interest and several tissue engineering approaches using different cell types have been proposed. Owing to the unsuitable nature of degenerate cells for tissue engineering, attention has been given to the use of mesenchymal stem cells (MSCs). In this connection, we have made a study on the characteristics of MSCs derived from adult bone marrow and on the feasibility of constructing IVD tissue-engineering cell under a Three-Dimensional Pellet Culture System. The human bone marrow MSCs were isolated and purified with density gradient solution and attachment-independent culture system. MSCs isolated using this method are a homogeneous population as indicated by morphology and other criteria. They have the capacity for self! -renewal and proliferation, and the multilineage potential to differentiate. PMID: 20095491 [PubMed - in process] | | |
| [Preparation of galactosylated hyaluronic acid/chitosan scaffold for liver tissue engineering]
January 26, 2010 at 7:22 AM
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| | [Preparation of galactosylated hyaluronic acid/chitosan scaffold for liver tissue engineering] Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2009 Dec;26(6):1271-5 Authors: Fan J, Shang Y, Yang J, Yuan Y The purpose of this research is to construct a kind of 3D-Scaffold with galactose-carrying polysaccharide for improving the function of hepatocytes in vitro. Galactose moieties were covalently coupled with hyaluronic acid through ethylenediamine. Galactosylated hyaluronic acid/chitosan scaffolds were prepared by lyophilization. The characteristics of the scaffolds such as morphology, hydrophilicity, and mechanical properties were investigated. The results indicated that the porosity and the pore size of the scaffolds made in -20 degrees C were useful used for culturing hepatocytes. And, the incorporating of hyaluronic acid in chitosan network improved the hydrophilicity and mechanical properties of the scaffolds. Rat primary hepatocytes growing in the scaffolds observed by phase-contrast microscope showed the multicellular spheroid morphologies. Therefore, galactosylated hyaluronic acid/chitosan scaffolds could be used as a promising scaffold for liver tissue engi! neering. PMID: 20095485 [PubMed - in process] | | |
| Drag reducing polymers improve tissue perfusion via modification of the RBC traffic in microvessels.
January 26, 2010 at 7:22 AM
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| | Drag reducing polymers improve tissue perfusion via modification of the RBC traffic in microvessels. Biorheology. 2009;46(4):281-92 Authors: Marhefka JN, Zhao R, Wu ZJ, Velankar SS, Antaki JF, Kameneva MV This paper reports a novel, physiologically significant, microfluidic phenomenon generated by nanomolar concentrations of drag-reducing polymers (DRP) dissolved in flowing blood, which may explain previously demonstrated beneficial effects of DRP on tissue perfusion. In microfluidic systems used in this study, DRP additives were found to significantly modify traffic of red blood cells (RBC) into microchannel branches as well as reduce the near-wall cell-free layer, which normally is found in microvessels with a diameter smaller than 0.3 mm. The reduction in plasma layer size led to attenuation of the so-called "plasma skimming" effect at microchannel bifurcations, increasing the number of RBC entering branches. In vivo, these changes in RBC traffic may facilitate gas transport by increasing the near vessel wall concentration of RBC and capillary hematocrit. In addition, an increase in near-wall viscosity due to the redirection of RBC in this region may potentially! decrease vascular resistance as a result of increased wall shear stress, which promotes endothelium mediated vasodilation. These microcirculatory phenomena can explain the previously reported beneficial effects of DRP on hemodynamics in vivo observed in many animal studies. We also report here our finding that DRP additives reduce flow separations at microchannel expansions, deflecting RBC closer to the wall and eliminating the plasma recirculation zone. Although the exact mechanism of the DRP effects on RBC traffic in microchannels is yet to be elucidated, these findings may further DRP progress toward clinical use. PMID: 19721190 [PubMed - indexed for MEDLINE] | | |
| Whole body regeneration in a colonial ascidian, Botrylloides violaceus.
January 26, 2010 at 7:22 AM
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| | Whole body regeneration in a colonial ascidian, Botrylloides violaceus. J Exp Zool B Mol Dev Evol. 2009 Dec 15;312(8):885-900 Authors: Brown FD, Keeling EL, Le AD, Swalla BJ Colonial ascidians are the only chordates to undergo whole body regeneration (WBR), the ability to form an entirely new individual from the peripheral vasculature. Here we describe WBR in Botrylloides violaceus, a colonial ascidian that reliably regenerates after ablation of all zooids and buds of young colonies. During early regeneration several buds develop within the tunic vasculature, but only one continues development into a complete zooid. We describe some of the first events of vascular budding leading to the vesicle stage with phase contrast microscopy, time-lapse video recording and detailed histological studies of regenerating colonies. The first conspicuous stage of vascular budding is when a single-layered sphere of cells becomes enclosed by vascular epithelium. We report the appearance of Piwi-positive cells in hemocytes surrounding the regenerates. We observed an increase of proliferating cell nuclear antigen (PCNA)-positive cells in circulatory hemo! cytes in late regenerates, and found double-labeled nuclear expression with Piwi in a subset of large circulatory cells. We rarely found Piwi or PCNA in differentiating tissues during vascular budding, suggesting that cells that form the epithelial tissues during budding and WBR originate mostly from circulatory hemocyte precursors. We propose that multiple stem cell types are circulating within B. violaceus and that they undergo proliferation in the peripheral vasculature before differentiating into epithelial tissues for all three germ layers during WBR. PMID: 19588490 [PubMed - indexed for MEDLINE] | | | |
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