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| Reinforcing Silk Scaffolds with Silk Particles.
February 19, 2010 at 10:09 AM
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| | Reinforcing Silk Scaffolds with Silk Particles. Macromol Biosci. 2010 Feb 18; Authors: Rajkhowa R, Gil ES, Kluge J, Numata K, Wang L, Wang X, Kaplan DL Silk fibroin is a useful protein polymer for biomaterials and tissue engineering. In this work, porogen leached scaffolds prepared from aqueous and HFIP silk solutions were reinforced through the addition of silk particles. This led to about 40 times increase in the specific compressive modulus and the yield strength of HFIP-based scaffolds. This increase in mechanical properties resulted from the high interfacial cohesion between the silk matrix and the reinforcing silk particles, due to partial solubility of the silk particles in HFIP. The porosity of scaffolds was reduced from approximately 90% (control) to approximately 75% for the HFIP systems containing 200% particle reinforcement, while maintaining pore interconnectivity. The presence of the particles slowed the enzymatic degradation of silk scaffolds. PMID: 20166230 [PubMed - as supplied by publisher] | | |
| Osteochondral repair using porous poly(lactide-co-glycolide)/nano-hydroxyapatite hybrid scaffolds with undifferentiated mesenchymal stem cells in a rat model.
February 19, 2010 at 10:09 AM
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| | Osteochondral repair using porous poly(lactide-co-glycolide)/nano-hydroxyapatite hybrid scaffolds with undifferentiated mesenchymal stem cells in a rat model. J Biomed Mater Res A. 2010 Feb 17; Authors: Xue D, Zheng Q, Zong C, Li Q, Li H, Qian S, Zhang B, Yu L, Pan Z In this study, a novel three-dimensional poly (lactide-co-glycolide) (PLGA)/nano-hydroxyapatite (NHA) scaffold was fabricated by a thermally induced phase separation technique and its potential application in cartilage tissue-engineering was investigated. The PLGA scaffold was used as a control and mesenchymal stem cells (MSCs) were seeded in both scaffolds. After 12-days culture, SEM images and confocal laser scanning microscopy illustrated that MSCs attached more moderately and more cells distributed in PLGA/NHA scaffolds. MTT test and DNA assay showed that the viability and proliferation of MSCs in PLGA/NHA scaffolds were significantly superior to PLGA scaffolds during in vitro culture. Through in vivo study, the efficacy of this scaffold combining with MSCs for repairing articular osteochondral defects was evaluated in a rat model. Osteochondral defects in rats knees were left untreated, or treated with PLGA/NHA-MSCs composites or PLGA-MSCs composites. Twelve ! weeks after operation, histological examination revealed that the defects in the PLGA/NHA-MSCs treated group were filled with smooth and hyaline-like cartilage with abundant glycosaminoglycan and collagen type II deposition, but deficient in collagen type I at 12 weeks after operation. To investigate the final fate of MSCs transplanted into the defect areas, the fluorescent dye CM-DiI was used to prelabel cells. At 12 weeks after transplantation, we still observed the red fluorescence in the repair area. These findings suggest that the PLGA/NHA-MSCs composite may be potentially used for cartilage repair in clinical application. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20166224 [PubMed - as supplied by publisher] | | |
| Evaluation of the biocompatibility and mechanical properties of naturally derived and synthetic scaffolds for urethral reconstruction.
February 19, 2010 at 10:09 AM
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| | Evaluation of the biocompatibility and mechanical properties of naturally derived and synthetic scaffolds for urethral reconstruction. J Biomed Mater Res A. 2010 Feb 17; Authors: Feng C, Xu YM, Fu Q, Zhu WD, Cui L, Chen J The aim of this study was to evaluate the mechanical properties and biocompatibility of biomaterials, including bladder submucosa (BAMG), small intestinal submucosa (SIS), acellular corpus spongiosum matrix (ACSM), and polyglycolic acid (PGA), to identify the optimal scaffold for urethral tissue engineering. Tensile mechanical testing was conducted to evaluate mechanical properties of each scaffold. Rabbit corporal smooth muscle cells were cultured with the extracts of biomaterials and mitochondrial metabolic activity assay was used to determine the cytotoxicity of scaffold. The pore sizes of each scaffold were measured. Additionally, smooth muscle cells were seeded on biomaterials. Cell infiltration was evaluated. Mechanical evaluation showed that Young modulus, stress at break in ACSM were prior to those in other biomaterials (p < 0.05). MTT assay confirmed that all scaffolds supported normal cellular mitochondrial metabolic without inducing cytotoxic events.! SEM demonstrated that PGA has the largest pore size (>200 mum). The ACSM has different pore sizes in urethral (<5 mum) and cavernosal surfaces (>10 mum). Widespread distribution of cells could be observed in PGA 14 days after seeding. Multilayer cellular coverage developed in BAMG and urethral surface of ACSM without any sign of cellular invasion. Moderated cellular penetration could be found in SIS and cavernosal surface of ACSM. Although each scaffold demonstrated suitable mechanical properties, which is similar to normal urethra, ACSM showed better response in some parameters than those in other biomaterials. It suggested that this scaffold may be an alternative for urethral reconstruction in the future. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20166222 [PubMed - as supplied by publisher] | | |
| Polycaprolactone/hydroxyapatite composite scaffolds: Preparation, characterization, and in vitro and in vivo biological responses of human primary bone cells.
February 19, 2010 at 10:09 AM
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| | Polycaprolactone/hydroxyapatite composite scaffolds: Preparation, characterization, and in vitro and in vivo biological responses of human primary bone cells. J Biomed Mater Res A. 2010 Feb 17; Authors: Chuenjitkuntaworn B, Inrung W, Damrongsri D, Mekaapiruk K, Supaphol P, Pavasant P Polycaprolactone (PCL) is a synthetic biodegradable polymer that has been approved for use as bone graft substitutes. In this study, PCL scaffolds incorporating hydroxyapatite (HAp) particles were fabricated by combined solvent casting and particulate leaching techniques. The average pore dimension was in the range of about 480-500 mum. The porosity, water absorption, and compressive modulus of the scaffold were evaluated. The responses of primary bone cells cultured on the PCL and PCL/HAp scaffolds were examined both in vitro and invivo. In comparison with the cells grown on the PCL scaffold, those cultured on the PCL/HAp counterpart positively expressed the markers of osteogenic differentiation. Cells increased the mRNA expressions of type I collagen and osteocalcin on day 10 and demonstrated a significant increase in calcium deposition. In coherence with the in vitro appearance, histomorphometric analysis in a mouse calvarial model showed a significantly greate! r amount of new bone formation. The results demonstrated that the prepared PCL/HAp scaffold could be a good candidate as synthetic substitute for bone tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20166220 [PubMed - as supplied by publisher] | | |
| Osteoblastic induction on calcium phosphate cement-chitosan constructs for bone tissue engineering.
February 19, 2010 at 10:09 AM
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| | Osteoblastic induction on calcium phosphate cement-chitosan constructs for bone tissue engineering. J Biomed Mater Res A. 2010 Feb 17; Authors: Weir MD, Xu HH Calcium phosphate cement (CPC) is osteoconductive and moldable, and it can conform to complex cavity shapes and set in situ to form hydroxyapatite. Chitosan could increase the strength and toughness of CPC, but there has been no investigation on recombinant human bone morphogenic protein-2 (rhBMP-2) delivery via CPC-chitosan composite and its effect on osteogenic induction of cells. The objective of this research was to investigate the mechanical properties and osteoblastic induction of MC3T3-E1 cells cultured on CPC-containing chitosan and rhBMP-2. Cell viability for CPC with chitosan and rhBMP-2 was comparable with that of control CPC, whereas the CPC-chitosan composite was stronger and tougher than CPC control. After 14 days, osteoblastic induction was quantified by measuring alkaline phosphatase (ALP) activity. ALP (mean +/- SD; n = 6) of cells seeded on conventional CPC without rhBMP-2 was (143 +/- 19) (mM pNpp/min)/(mug DNA). The addition of chitosan resulte! d in an ALP of 161 +/- 27. Further addition of rhBMP-2 to the CPC-chitosan composite increased the ALP to 305 +/- 111 (p < 0.05). All ALP activity on CPC composites was significantly higher when compared with the 10.0 +/- 3.3 of tissue culture polystyrene (p < 0.05). Flexural strength of CPC containing 15% (mass fraction) chitosan was 19.8 +/- 1.4 MPa, which is more than double the 8.0 +/- 1.4 MPa of conventional CPC (p < 0.05). The addition of chitosan to CPC increased the fracture toughness from 0.18 +/- 0.01 MPa.m(1/2) to 0.23 +/- 0.02 MPa.m(1/2) (p < 0.05). The relatively high strength, self-hardening CPC-chitosan composite scaffold is promising as a moderate load-bearing matrix for bone repair, with potential to serve as an injectable delivery vehicle for osteoinductive growth factors to promote osteoblastic induction and bone regeneration. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20166217 [PubMed - as supplied by publisher] | | |
| Fabrication and characterization of a porous multidomain hydroxyapatite scaffold for bone tissue engineering investigations.
February 19, 2010 at 10:09 AM
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| | Fabrication and characterization of a porous multidomain hydroxyapatite scaffold for bone tissue engineering investigations. J Biomed Mater Res B Appl Biomater. 2010 Feb 17; Authors: Buckley CT, O'Kelly KU Tissue-engineering scaffold-based strategies have suffered from limited cell depth viability when cultured in vitro, with viable cells existing within the outer periphery of the fluid-scaffold interface. This is primarily believed to be due to the lack of nutrient delivery into and waste removal from the inner regions of the scaffold construct. This work develops a hydroxyapatite trimodal porous scaffold architecture (i.e., a scaffold providing a discrete domain for cell occupancy and a separate domain for nutrient delivery) through a freeze drying process. Unidirectional channels (500 mum diameter) were incorporated through CNC machining with total combined apparent porosities of 85.1% +/- 0.22%. Effective diffusion coefficients for the bimodal phase (consisting of micro- and meso-pores, without channels) were also determined (7.9 x 10(-10) m(2) s(-1)). Trimodal scaffolds also demonstrated enhanced permeability values ( approximately 18-fold increase) compared wi! th bimodal scaffold architectures. In vitro experiments were used to assess initial seeding efficiency and distribution as well as cell viability. The presence of unidirectional channels significantly enhanced initial cell seeding distribution throughout the scaffold depth, while maintaining relatively high seeding efficiencies (67.7% +/- 2.2% for trimodal, 79.1% +/- 2.1% for bimodal scaffolds). Numerical models demonstrated the effectiveness and efficacy of incorporating channels to increase the core oxygen concentration, with the accuracy of these models improved by using experimentally measured cellular oxygen consumption rates and effective diffusion coefficients. The presence of channels had a positive influence in minimizing the concentration gradients compared with bimodal scaffolds for the same cell density distributions. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20166121 [PubMed - as supplied by publisher] | | |
| Regulatory T cells contribute to the protective effect of ischemic preconditioning in the kidney.
February 19, 2010 at 10:09 AM
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| | Regulatory T cells contribute to the protective effect of ischemic preconditioning in the kidney. Kidney Int. 2010 Feb 17; Authors: Kinsey GR, Huang L, Vergis AL, Li L, Okusa MD Reperfusion following ischemia is associated with acute kidney injury and inflammation. Using a mouse model, we exposed the kidney to a nonlethal period of ischemia, rendering it refractory to future ischemia-induced dysfunction. This ischemic preconditioning is partially mediated by Treg lymphocytes that suppress immune responses. We found that this maneuver significantly inhibited the accumulation of neutrophils and macrophages, tubular necrosis, and loss of kidney function caused by a subsequent ischemia/reperfusion injury 1 week later. The initial ischemia/reperfusion caused a significant increase in CD4(+)CD25(+)FoxP3(+) and CD4(+)CD25(+)IL-10(+) Treg cells within the kidney at 7 days of reperfusion. Treatment of preconditioned mice with a Treg cell-depleting antibody (PC61) reversed the effect of preconditioning on kidney neutrophil accumulation and partially inhibited the functional and histological protection of preconditioning. Adoptive transfer of Treg c! ells in naive mice, before ischemia/reperfusion, mimicked the protective and anti-inflammatory effects of ischemic preconditioning on the kidney. These studies highlight the role of Treg cells in ischemic preconditioning.Kidney International advance online publication, 17 February 2010; doi:10.1038/ki.2010.12. PMID: 20164824 [PubMed - as supplied by publisher] | | |
| Elevation of Zinc Transporter ZnT3 Protein in the Cerebellar Cortex of the AbetaPP/PS1 Transgenic Mouse.
February 19, 2010 at 10:09 AM
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| | Elevation of Zinc Transporter ZnT3 Protein in the Cerebellar Cortex of the AbetaPP/PS1 Transgenic Mouse. J Alzheimers Dis. 2010 Feb 17; Authors: Zheng W, Wang T, Yu D, Feng WY, Nie YX, Stoltenberg M, Danscher G, Wang ZY The presence of senile plaques containing abundant amyloid-beta (Abeta) peptide is one of the major pathological hallmarks of Alzheimer's disease (AD). Recent studies support the notion that overexpression of zinc transporters (ZnT) is involved in zinc metabolic disturbances and Abeta aggregation in AD brains. Here we present data showing an elevated expression of zinc transporter 3 (ZnT3) protein, revealed by immunoblotting assay, in the cerebellum of the amyloid-beta protein precursor (AbetaPP)/presenilin 1 (PS1) transgenic mouse. Confocal microscopic and autometallographic results showed that ZnT3 immunofluorescence and zinc ions were predominantly located in the amyloid plaques. ZnT3 protein was abundantly distributed throughout the plaques, whereas zinc ions were mainly located in the peripheral parts of rosette-shaped plaques with a lightly stained center. Collectively, our results suggest that ZnT3 protein is involved in the Abeta aggregation in the cerebel! lum of the AbetaPP/PS1 mouse. PMID: 20164588 [PubMed - as supplied by publisher] | | |
| Preparation and characterization of decellularized cornea using high-hydrostatic pressurization for corneal tissue engineering.
February 19, 2010 at 10:09 AM
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| | Preparation and characterization of decellularized cornea using high-hydrostatic pressurization for corneal tissue engineering. Biomaterials. 2010 Feb 15; Authors: Hashimoto Y, Funamoto S, Sasaki S, Honda T, Hattori S, Nam K, Kimura T, Mochizuki M, Fujisato T, Kobayashi H, Kishida A To prepare acellular corneal scaffold, we used high-hydrostatic pressurization (HHP) to decellularize porcine cornea. The HHP method disrupts cells by hydrostatic pressurization, and then the disrupted cells' components are removed by washing with a cell culture medium. Porcine corneas were hydrostatically pressed at 980MPa at 10 or 30 degrees C for 10min to make them opaque. There was no change in the thickness of the corneas immediately after the pressurization, but they swelled during the washing process. The cornea swelling caused by HHP was suppressed when medium containing 3.5% w/v dextran was used. For H-E staining of the cornea decellularized with the HHP method, the complete removal of corneal cells was confirmed. Furthermore, when the corneas were immersed in glycerol for 1hour, their optical properties were restored to those of native corneas. In an animal study, when acellular porcine corneas were implanted into rabbit cornea, no immune reaction occurr! ed and the turbid corneas became clear. The decellularized corneas obtained through HHP could be useful as a corneal scaffold for tissue regeneration. PMID: 20163852 [PubMed - as supplied by publisher] | | |
| Quantitative monitoring of lipid accumulation over time in cultured adipocytes as function of culture conditions: Towards controlled adipose tissue engineering.
February 19, 2010 at 10:09 AM
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| | Quantitative monitoring of lipid accumulation over time in cultured adipocytes as function of culture conditions: Towards controlled adipose tissue engineering. Tissue Eng Part C Methods. 2010 Feb 17; Authors: Or-Tzadikario S, Sopher R, Gefen A Adipose tissue engineering is investigated for native fat substitutes and wound healing model systems. Research and clinical applications of bioartificial fat require a quantitative and objective method to continuously measure adipogenesis in living cultures as opposed to currently used culture-destructive techniques that stain lipid droplet (LD) accumulation. To allow standardization, automatic quantification of LD sizes is further needed, but currently LD sizes are measured mostly manually. We developed an image-processing-based method which does not require staining to monitor adipose cell maturation in vitro non-destructively using optical micrographs taken consecutively during culturing. We employed our method to monitor LD accumulation in 3T3-L1 and mesenchymal stem cells (MSC) over 37 days. For each cell type, percentage lipid area, number of droplets per cell and droplet diameter were obtained every 2-3 days. In 3T3-L1 cultures, high insulin concentration ! (10mug/ml) yielded a significantly different (p<0.01) timecourse of all 3 outcome measures. In MSC cultures, high FBS concentration (12.5%) produced significantly more lipid area (p<0.01). Our method was able to successfully characterize timecourses and extents of adipogenesis, and is useful for a wide range of applications testing the effects of biochemical, mechanical and thermal stimulations in tissue engineering of bioartificial fat constructs. PMID: 20163242 [PubMed - as supplied by publisher] | | |
| Comparison of Potentials between Stem Cells Isolated from Human Anterior Cruciate Ligament and Bone Marrow for Ligament Tissue Engineering.
February 19, 2010 at 10:09 AM
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| | Comparison of Potentials between Stem Cells Isolated from Human Anterior Cruciate Ligament and Bone Marrow for Ligament Tissue Engineering. Tissue Eng Part A. 2010 Feb 17; Authors: Cheng MT, Liu CL, Chen TH, Lee OK We have previously isolated and identified stem cells from human anterior cruciate ligament (ACL). The purpose of this study was to evaluate the differences in proliferation, differentiation, and extracellular matrix (ECM) formation abilities between bone marrow stem cells (BMSCs) and ACL-derived stem cells (LSCs) from the same donors when cultured with different growth factors including basic fibroblast growth factor (bFGF), epidermal growth factor (EGF), and transforming growth factor-beta 1 (TGF-beta1). Ligament tissues and bone marrow aspirate were obtained from patients undergoing total knee arthroplasty and ACL reconstruction surgeries. Proliferation, colony formation, and population doubling capacity as well as multi-lineage differentiation potentials of LSCs and BMSCs were compared. Gene expression and ECM production for ligament engineering were also evaluated. It was found that BMSCs possessed better osteogenic differentiation potentials then LSCs, while! similar adipogenic and chondrogenic differentiation abilities were observed. Proliferation rates of both LSCs and BMSCs were enhanced by bFGF and TGF-beta1. TGF-beta1 treatment significantly increased the expression of type I collagen, type III collagen, fibronectin, and alpha-smooth muscle actin (alpha-SMA) in LSCs, but TGF-beta1 only up-regulated type I collagen and tenascin-c on BMSCs. Protein quantification further confirmed the results of differential gene expression and suggested that LSCs and BMSCs increase ECM production upon TGF-beta1 treatment. In summary, in comparison with BMSCs, LSCs proliferate faster and maintain undifferentiated with bFGF treatment, while under TGF-beta1 treatment, LSCs upregulate major tedinous gene expression and produce a robust amount of ligament ECM protein, making LSCs a potential cell source in future applications of ACL tissue engineering. PMID: 20163211 [PubMed - as supplied by publisher] | | |
| Ethical aspects of soft tissue engineering for congenital birth defects in children - What do experts in the field say?
February 19, 2010 at 10:09 AM
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| | Ethical aspects of soft tissue engineering for congenital birth defects in children - What do experts in the field say? Tissue Eng Part B Rev. 2010 Feb 17; Authors: Oerlemans AJ, Rodrigues CH, Verkerk MA, van den Berg PP, Dekkers WJ This paper is part of the EuroSTEC project, which aims at developing tissue engineering-based treatments for structural disorders present at birth. EuroSTEC is positioned at the intersection of three areas with their own ethical issues: (1) regenerative medicine, (2) research with pregnant women and fetuses, and (3) research with neonates. Because of the overlap of these three areas in this project, we can expect to be confronted with new ethical challenges. To be able to respond adequately and timely to current and possible future ethical issues, a prospective and anticipatory ethical analysis is essential. To obtain a first survey of ethical issues that might arise during the different phases of the project, the Delphi method was used. The professionals directly involved in the EuroSTEC project were questioned about their views on possible ethical issues. The first round yielded 27 ethical issues that the respondents were asked to prioritize in the second round.! For the fundamental research phase, issues deemed most important were privacy and informed consent of the tissue donor. For the animal experimentation phase, three issues were mentioned (in order of decreasing priority): the suffering of animals, the use of animals as means to an end, and the limited adequacy of the animal models. Issues that were deemed most important during the clinical (trial) phase pertained to the problem of weighing risks and benefits for the fetus/child and the pregnant woman. PMID: 20163208 [PubMed - as supplied by publisher] | | |
| Mesenchymal Stem Cells, Osteoblasts And Extracellular Matrix (ECM) Proteins: Enhancing Cell Adhesion And Differentiation For Bone Tissue Engineering.
February 19, 2010 at 10:09 AM
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| | Mesenchymal Stem Cells, Osteoblasts And Extracellular Matrix (ECM) Proteins: Enhancing Cell Adhesion And Differentiation For Bone Tissue Engineering. Tissue Eng Part B Rev. 2010 Feb 17; Authors: Hidalgo-Bastida LA, Cartmell S Cell adhesion to scaffolds has remained one of the challenges in tissue engineering. Although protein surface-modification has been proven to enhance cell adhesion and retention, its specificity depending on cell and biomaterial types means that the best protein and concentration must be established for each specific application. This review focuses on the improvement of cell adhesion for human mesenchymal stem cells (MSCs) with an osteogenesis approach. A brief outline of the cell adhesion process and extracellular matrix (ECM) proteins precedes an overview of works focused on the adhesion of MSCs and osteoblasts to biomaterials and this effect in their differentiation into osteoblasts. PMID: 20163206 [PubMed - as supplied by publisher] | | |
| Gli2 trafficking links Hedgehog-dependent activation of Smoothened in the primary cilium to transcriptional activation in the nucleus.
February 19, 2010 at 10:09 AM
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| | Gli2 trafficking links Hedgehog-dependent activation of Smoothened in the primary cilium to transcriptional activation in the nucleus. Proc Natl Acad Sci U S A. 2009 Dec 22;106(51):21666-71 Authors: Kim J, Kato M, Beachy PA Stimulation by the extracellular Hedgehog (Hh) protein signal has been shown to alter ciliary localization of the mammalian Hh receptor components Smoothened (Smo) and Patched (Ptc), and mutations that disrupt the structure and function of the cilium also disrupt Hh-induced changes in gene expression. But how ciliary events affect gene expression in the nucleus is not known, and to address this question we have characterized the cellular trafficking of Gli2, the principal mediator of Hh-dependent transcriptional activation. From a combination of pharmacological and genetic manipulations we find in resting cells that both Gli2 and Smo appear to shuttle in and out of the cilium, with Gli2 but not Smo requiring intact cytoplasmic microtubules for ciliary entry and both requiring the ciliary retrograde motor, cytoplasmic dynein 2, for ciliary exit. We also find that changes in ciliary and nuclear trafficking of Gli2 are triggered by the Hh-dependent accumulation of ac! tivated Smo in the cilium, resulting in a shift from primarily cytoplasmic localization to accumulation at the distal tip of the cilium and within the nucleus. Gli2 thus functions as a dynamic monitor of Smo activity in the cilium and thereby links Hh pathway activation in the cilium to transcriptional activation in the nucleus. PMID: 19996169 [PubMed - indexed for MEDLINE] | | |
| Human cloning, stem cell research. An Islamic perspective.
February 19, 2010 at 10:09 AM
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| | Human cloning, stem cell research. An Islamic perspective. Saudi Med J. 2009 Dec;30(12):1507-14 Authors: Al-Aqeel AI The rapidly changing technologies that involve human subjects raise complex ethical, legal, social, and religious issues. Recent advances in the field of cloning and stem cell research have introduced new hopes for the treatment of serious diseases. But this promise has raised many complex questions. This field causes debate and challenge, not only among scientists but also among ethicists, religious scholars, governments, and politicians. There is no consensus on the morality of human cloning, even within specific religious traditions. In countries in which religion has a strong influence on political decision making, the moral status of the human embryo is at the center of the debate. Because of the inevitable consequences of reproductive cloning, it is prohibited in Islam. However, stem cell research for therapeutic purposes is permissible with full consideration, and all possible precautions in the pre-ensoulment stages of early fetus development, if the sourc! e is legitimate. PMID: 19936411 [PubMed - indexed for MEDLINE] | | |
| Biosurface engineering through ink jet printing.
February 19, 2010 at 10:09 AM
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| | Biosurface engineering through ink jet printing. Colloids Surf B Biointerfaces. 2010 Feb 1;75(2):441-7 Authors: Khan MS, Fon D, Li X, Tian J, Forsythe J, Garnier G, Shen W The feasibility of thermal ink jet printing as a robust process for biosurface engineering was demonstrated. The strategy investigated was to reconstruct a commercial printer and take advantage of its colour management interface. High printing resolution was achieved by formulating bio-inks of viscosity and surface tension similar to those of commercial inks. Protein and enzyme denaturation during thermal ink jet printing was shown to be insignificant. This is because the time spent by the biomolecules in the heating zone of the printer is negligible; in addition, the air and substrate of high heat capacity absorb any residual heat from the droplet. Gradients of trophic/tropic factors can serve as driving force for cell growth or migration for tissue regeneration. Concentration gradients of proteins were printed on scaffolds to show the capability of ink jet printing. The printed proteins did not desorb upon prolonged immersion in aqueous solutions, thus allowing ! printed scaffold to be used under in vitro and in vivo conditions. Our group portrait was ink jet printed with a protein on paper, illustrating that complex biopatterns can be printed on large area. Finally, patterns of enzymes were ink jet printed within the detection and reaction zones of a paper diagnostic. PMID: 19879112 [PubMed - indexed for MEDLINE] | | |
| Lysyl oxidase enhances elastin synthesis and matrix formation by vascular smooth muscle cells.
February 19, 2010 at 10:09 AM
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| | Lysyl oxidase enhances elastin synthesis and matrix formation by vascular smooth muscle cells. J Tissue Eng Regen Med. 2009 Dec;3(8):655-61 Authors: Kothapalli CR, Ramamurthi A Lysyl oxidase (LOX) is a copper-dependent enzyme that initiates covalent crosslinking of elastin precursors by oxidizing peptidyl lysine to aminoadipic semi-aldehydes. Previous studies have shown LOX deficiency to affect crosslinking of elastin and collagen in vivo, resulting in disorganized connective tissue formation. In this study, we investigated the utility of exogenously supplemented LOX peptides (50-100 microl/well) to elastin synthesis, crosslinking efficiency and matrix deposition in adult rat aortic smooth muscle cell (RASMC) cultures. Additionally, we also examined the role of LOX peptides on SMC proliferation and matrix metalloproteinase (MMP) synthesis in these cultures. Highly purified bovine aorta LOX peptide was found to increase matrix elastin synthesis by 40-80% to that in control cultures in a dose-dependent manner, while the crosslinking efficiency significantly (as measured by the ratio of matrix elastin protein to the total elastin protein sy! nthesized) improved to 45-55% of total elastin synthesized under these conditions. However, LOX peptides affected neither SMC proliferation relative to controls, nor elastin precursor (tropoelastin) synthesis, nor the total elastin synthesis on a per-cell basis. In general, LOX peptides also did not affect MMP-2 and MMP-9 activities relative to control cultures, except for MMP-9 activity suppression at a higher LOX dose, suggesting that these LOX peptide cues could be safely used to enhance tropoelastin crosslinking into matrix structures and elastin matrix yield, within tissue-engineered constructs, a major challenge in the field. PMID: 19813219 [PubMed - indexed for MEDLINE] | | |
| Engineered human skin substitutes undergo large-scale genomic reprogramming and normal skin-like maturation after transplantation to athymic mice.
February 19, 2010 at 10:09 AM
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| | Engineered human skin substitutes undergo large-scale genomic reprogramming and normal skin-like maturation after transplantation to athymic mice. J Invest Dermatol. 2010 Feb;130(2):587-601 Authors: Klingenberg JM, McFarland KL, Friedman AJ, Boyce ST, Aronow BJ, Supp DM Bioengineered skin substitutes can facilitate wound closure in severely burned patients, but deficiencies limit their outcomes compared with native skin autografts. To identify gene programs associated with their in vivo capabilities and limitations, we extended previous gene expression profile analyses to now compare engineered skin after in vivo grafting with both in vitro maturation and normal human skin. Cultured skin substitutes were grafted on full-thickness wounds in athymic mice, and biopsy samples for microarray analyses were collected at multiple in vitro and in vivo time points. Over 10,000 transcripts exhibited large-scale expression pattern differences during in vitro and in vivo maturation. Using hierarchical clustering, 11 different expression profile clusters were partitioned on the basis of differential sample type and temporal stage-specific activation or repression. Analyses show that the wound environment exerts a massive influence on gene expr! ession in skin substitutes. For example, in vivo-healed skin substitutes gained the expression of many native skin-expressed genes, including those associated with epidermal barrier and multiple categories of cell-cell and cell-basement membrane adhesion. In contrast, immunological, trichogenic, and endothelial gene programs were largely lacking. These analyses suggest important areas for guiding further improvement of engineered skin for both increased homology with native skin and enhanced wound healing. PMID: 19798058 [PubMed - indexed for MEDLINE] | | |
| Polyurethane-based leukocyte-inspired biocidal materials.
February 19, 2010 at 10:09 AM
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| | Polyurethane-based leukocyte-inspired biocidal materials. Biomaterials. 2009 Nov;30(33):6522-9 Authors: Amitai G, Andersen J, Wargo S, Asche G, Chir J, Koepsel R, Russell AJ During the neutrophil respiratory burst myeloperoxidase uses hydrogen peroxide and chloride ion to generate hypochlorite which kills pathogens. Synthetic antimicrobial materials based on this chemistry are described herein. The oxidizing enzymes glucose oxidase (GOX) and horseradish peroxidase (HRP) catalyze two reactions in tandem using glucose, hydrogen peroxide and sodium halide (iodide or bromide). The final product of these two consecutive enzymatic reactions is either iodine or bromine. HRP, acting as haloperoxidase, utilizes the H(2)O(2) generated by GOX to oxidize halide ions into free halogens. Typically, 15 units/ml HRP and 25 units/ml GOX reacted with 0.8mm NaI and 5mm glucose to generate 5-7 ppm free iodine within 30 min. Medical grade polyurethane ChronoFlex AR (CF) was electrospun together with GOX and HRP. The electrospun fibers were collected as a uniform, water-insoluble, flexible elastomeric matrix with an average fiber diameter of 1+/-0.2 microm! . Biocidal activity of CF/enzyme fibers resulted in >6-log unit reduction of both Escherichia coli and Staphylococcus aureus challenges. A time-course of biocidal activity displayed a 3-4 log reduction of E. coli and S. aureus within the first 5 min and complete kill (>6 logs) within 15 min. A dose-response study of fiber weight (0.5-30 mg/ml) exhibited complete kill of E. coli (>6 logs) and at least 99.99% S. aureus kill (>4 logs) with as little as 1mg fiber. The fibers were reusable with slightly less activity on the second use and significant activity after continuous soaking in buffer for up to 7 days. Electrospun CF/GOX/HRP fibers adhered to a thin film with embedded NaI and glucose caused a complete kill of E. coli (>7-log units) and MRSA (6-log unit reduction) within 1h at 37 degrees C. PMID: 19733392 [PubMed - indexed for MEDLINE] | | |
| Determination of critical size defect of minipig mandible.
February 19, 2010 at 10:09 AM
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| | Determination of critical size defect of minipig mandible. J Tissue Eng Regen Med. 2009 Dec;3(8):615-22 Authors: Ma JL, Pan JL, Tan BS, Cui FZ The critical size defect (CSD) of bone can provide a standard for evaluating the usefulness of bone repair materials or methods. The present study aimed to determine the CSDs of the minipig mandible with and without the periosteum. Ten 18 month-old female minipigs were used. First, the premolars and the first molar in the right mandible of each minipig were extracted. Two months later, the animals were randomly divided into two groups, with six animals in group A and four in group B. In group A, bone segments of 4, 5 and 6 cm were removed from the right mandible and the neighbouring periosteum was preserved. In group B, bone segments of 1 and 2 cm were removed from the right mandible and the periosteum was removed. The defects were retained with two reconstructive titanium plates. The mandibles underwent X-ray examinations at 4, 8 and 12 weeks after the operation. The animals were sacrificed at 12 weeks after the operation, and specimens were evaluated by gross an! d histological examinations. For defects retained by two reconstructive plates, the CSDs in the minipig mandible models with and without periosteum were determined as 6 and 2 cm, respectively. PMID: 19731258 [PubMed - indexed for MEDLINE] | | |
| Evidence of innervation following extracellular matrix scaffold-mediated remodelling of muscular tissues.
February 19, 2010 at 10:09 AM
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| | Evidence of innervation following extracellular matrix scaffold-mediated remodelling of muscular tissues. J Tissue Eng Regen Med. 2009 Dec;3(8):590-600 Authors: Agrawal V, Brown BN, Beattie AJ, Gilbert TW, Badylak SF Naturally occurring porcine-derived extracellular matrix (ECM) has successfully been used as a biological scaffold material for site-specific reconstruction of a wide variety of tissues. The site-specific remodelling process includes rapid degradation of the scaffold, with concomitant recruitment of mononuclear, endothelial and bone marrow-derived cells, and can lead to the formation of functional skeletal and smooth muscle tissue. However, the temporal and spatial patterns of innervation of the remodelling scaffold material in muscular tissues are not well understood. A retrospective study was conducted to investigate the presence of nervous tissue in a rat model of abdominal wall reconstruction and a canine model of oesophageal reconstruction in which ECM scaffolds were used as inductive scaffolds. Evidence of mature nerve, immature nerve and Schwann cells was found within the remodelled ECM at 28 days in the rat body wall model, and at 91 days post surgery in a! canine model of oesophageal repair. Additionally, a microscopic and morphological study that investigated the response of primary cultured neurons seeded upon an ECM scaffold showed that neuronal survival and outgrowth were supported by the ECM substrate. Finally, matricryptic peptides resulting from rapid degradation of the ECM scaffold induced migration of terminal Schwann cells in a concentration-dependent fashion in vitro. The findings of this study suggest that the reconstruction of tissues in which innervation is an important functional component is possible with the use of biological scaffolds composed of extracellular matrix. PMID: 19701935 [PubMed - indexed for MEDLINE] | | |
| Impact of human amniotic membrane preparation on release of angiogenic factors.
February 19, 2010 at 10:09 AM
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| | Impact of human amniotic membrane preparation on release of angiogenic factors. J Tissue Eng Regen Med. 2009 Dec;3(8):651-4 Authors: Wolbank S, Hildner F, Redl H, van Griensven M, Gabriel C, Hennerbichler S Preserved amniotic membrane (AM) has been used in the field of ophthalmology and wound care due to its bacteriostatic, antiphlogistic, protease-inhibiting, re-epithelialization, wound-protecting and scar formation-reducing properties. Typically, AM is applied after banking in a glycerol-preserved or freeze-dried state. Cell viabilities in different forms of preparation vary substantially, which in consequence may also be reflected in the amount and type of growth factors released from the preserved material. Therefore, we characterized the angiogenic factor (AF) profile released from different AM preparations. For this, medium was conditioned with non-preserved, glycerol- and cryo-preserved AM for 48 h, which was screened for AFs using a protein array system. In parallel, the preparations were tested for cell viability. Non-preserved as well as cryo-preserved AM maintained viabilities at 106.5 +/- 23.9% and 21.9 +/- 23.3%, respectively, whereas glycerol-preserved ! AM was found to be non-viable. Of the 20 investigated factors, high levels of angiogenin, GRO, IL-6/8, TIMP-1/2 and MCP-1 and low levels of EGF, IFNgamma, IGF-1, leptin, RANTES, TGFbeta1 and thrombopoietin were identified to be secreted from non-preserved AM. Cryo-preserved AM secreted high levels of IL-8, intermediate levels of GRO and TIMP-1/2 but only low levels of angiogenin, IFNgamma, IL-6 and MCP-1 and no detectable EGF, IGF-1, leptin, RANTES, TGFbeta1 and thrombopoietin. After banking in glycerol, AM releases only minute amounts of TIMP-1/2. Along with viability, the AF profile of amniotic membrane largely depends on the preparation method applied for banking. This should be considered for selection of an AM product for a specific clinical application. PMID: 19701933 [PubMed - indexed for MEDLINE] | | |
| Repairing large bone fractures with low frequency electromagnetic fields.
February 19, 2010 at 10:09 AM
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| | Repairing large bone fractures with low frequency electromagnetic fields. J Orthop Res. 2010 Feb;28(2):265-70 Authors: Lin HY, Lu KH The healing effects of low frequency pulse electromagnetic field (EMF) on bone fractures larger than 1 cm are unsatisfactory. Three- dimensional chitosan scaffolds are designed to fill in larger bone fractures and have been shown to be osteogenic. We hypothesized that EMF could accelerate the repair process of larger bone fractures with the use of chitosan scaffolds. Chitosan (96% deacetylation) films and lyophilized scaffolds, with and without osteoblast cells, were exposed to EMF (18-30 Gauss, 75 Hz) for 2 h a day for 3 weeks. Each week, the growth and phenotype expressions of osteoblasts and properties of chitosan were examined. The hydrophilicity, Young's modulus, and biodegradability of chitosan were not altered by EMF exposure. EMF osteoblasts showed 37% higher cell proliferation, 15% lower alkaline phosphatase activity, and 74% more calcium deposition than the controls. Based on SEM photomicrographs, EMF- treated cells appeared to produce more collagen fibr! ils, matrix vesicles, and calcium in the extracellular matrix than the controls. In conclusion, EMF was capable of enhancing the proliferation and mineralization of osteoblasts cultured on chitosan scaffolds. PMID: 19639630 [PubMed - indexed for MEDLINE] | | | | 
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