| Evidence of innervation following extracellular matrix scaffold-mediated remodelling of muscular tissues.
August 25, 2009 at 11:46 am
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| | Evidence of innervation following extracellular matrix scaffold-mediated remodelling of muscular tissues. J Tissue Eng Regen Med. 2009 Aug 21; 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. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19701935 [PubMed - as supplied by publisher] |
| Biomimetic Ca-P coatings incorporating bisphosphonates produced on starch-based degradable biomaterials.
August 25, 2009 at 11:46 am
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| | Biomimetic Ca-P coatings incorporating bisphosphonates produced on starch-based degradable biomaterials. J Biomed Mater Res B Appl Biomater. 2009 Aug 21; Authors: Oliveira AL, Pedro AJ, Arroyo CS, Mano JF, Rodriguez G, Roman JS, Reis RL In this study, sodium clodronate, a well-known therapeutic agent from the family of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating, previously formed on the surface of a starch-based biomaterial by a sodium silicate methodology, as a strategy to develop a site-specific drug delivery system for bone tissue regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the release profiles of sodium clodronate was also assessed. As a preliminary approach, this first study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic cell line since there is still little information available on the interaction between BPs and this type of cells. Sodium clodronate was successfully incorporated, at different doses, in the structure of a biomimetic CaP layer previously formed by a sodium silicate process. This type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be produced on the surface of degradable polymers and then used for regulating the equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect at the interface between the biomaterial and bone. (c) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009. PMID: 19701915 [PubMed - as supplied by publisher] |
| A molecularly defined array based on native fibrillar collagen for the assessment of skin tissue engineering biomaterials.
August 25, 2009 at 11:46 am
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| | A molecularly defined array based on native fibrillar collagen for the assessment of skin tissue engineering biomaterials. Biomaterials. 2009 Aug 20; Authors: Lammers G, Tjabringa GS, Schalkwijk J, Daamen WF, van Kuppevelt TH Large-scale in vivo evaluation of biomaterials is time-consuming and limited by ethical considerations. The availability of a library of biomaterials would allow a fast and rational in vitro selection of those biomaterials to be evaluated in vivo. For this reason, we developed an array of 48 different, molecularly-defined films based on native fibrillar collagen. The films differed in the type and amount of extracellular matrix components (type I/IV collagens, fibrous/solubilised elastin, glycosaminoglycans, heparin, chondroitin sulfate or dermatan sulfate), method of preparation (homogenisation) and method and extent of crosslinking (carbodiimide (EDC/NHS) or glutaraldehyde). The array was evaluated by studying morphology, proliferation and differentiation of primary human keratinocytes/fibroblasts. Major differences were observed. Only a small selection of films (especially those containing elastin fibres) specifically stimulated the proliferation of keratinocytes, but not fibroblasts. Such films may be the biomaterials of choice for in vivo evaluation for skin tissue engineering and regenerative medicine. PMID: 19699517 [PubMed - as supplied by publisher] |
| The role of hypoxia in MSCs: Considerations for regenerative medicine approaches.
August 25, 2009 at 11:46 am
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| | The role of hypoxia in MSCs: Considerations for regenerative medicine approaches. Tissue Eng Part B Rev. 2009 Aug 21; Authors: Das R, Jahr H, van Osch G, Farrell E Bone marrow derived mesenchymal stem cells (MSCs) have demonstrated potential for regenerative medicine strategies. Knowledge of the way these cells respond to their environment in in-vitro culture and after implantation in vivo is crucial for successful therapy. Oxygen tension plays a pivotal role in both situations. In vivo, a hypoxic environment can lead to apoptosis but hypoxic preconditioning of MSCs and overexpression of pro-survival genes like Akt can reduce hypoxia-induced cell death. In cell culture, hypoxia can increase proliferation rates and enhance differentiation along the different mesenchymal lineages. Hypoxia also modulates the paracrine activity of MSCs, causing upregulation of various secretable factors, among which are important angiogenic factors such as VEGF and IL-6. Finally, hypoxia plays an important role in mobilization and homing of MSCs, primarily by its ability to induce SDF-1 expression along with its receptor CXCR4. This paper reviews the current literature on the effects of hypoxia on MSCs and aims to elucidate its potential role in regenerative medicine strategies. PMID: 19698058 [PubMed - as supplied by publisher] |
| Icariin: A Potential Osteoinductive Compound for Bone Tissue Engineering.
August 25, 2009 at 11:46 am
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| | Icariin: A Potential Osteoinductive Compound for Bone Tissue Engineering. Tissue Eng Part A. 2009 Aug 21; Authors: Zhao J, Ohba S, Komiyama Y, Shinkai M, Chung UI, Nagamune T To effectively treat bone diseases using bone regenerative medicine, there is an urgent need to develop safe and cheap drugs that can potently induce bone formation. Here, we demonstrate the osteogenic effects of icariin, the main active compound of Epimedium pubescens. Icariin induced osteogenic differentiation of pre-osteoblastic cells. The combination of icariin and a helioxanthin-derived small compound synergistically induced osteogenic differentiation of MC3T3-E1 cells to a similar extent to bone morphogenetic protein (BMP)-2. Icariin enhanced the osteogenic induction activity of BMP-2 in a fibroblastic cell line. Mineralization was enhanced by treatment with a combination of icariin and calcium-enriched medium. The in vivo anabolic effect of icariin was confirmed in a mouse calvarial defect model. Eight-week-old male C57BL/6N mice were transplanted with icariin-calcium phosphate cement (CPC) tablets or CPC tablets only (n=5 for each), and bone regeneration was evaluated after 4 and 6 weeks. Significant new bone formation was observed in the icariin-CPC group at 4 weeks and the new bone thickness had increased by 6 weeks. Obvious blood vessel formation was observed in the icariin-induced new bone. Treatment of senescence-accelerated mouse prone 1 and senescence-accelerated mouse prone 6 models further demonstrated that icariin was able to enhance bone formation in vivo. Therefore, icariin is a strong candidate for an osteogenic compound for use in bone tissue engineering. PMID: 19698057 [PubMed - as supplied by publisher] |
| [Transcriptional network controlling pluripotency in embryonic stem cells]
August 25, 2009 at 11:46 am
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| | [Transcriptional network controlling pluripotency in embryonic stem cells] Seikagaku. 2009 Jul;81(7):597-601 Authors: Masui S PMID: 19697863 [PubMed - in process] |
| Force generation and protease gene expression in organotypic co-cultures of fibroblasts and keratinocytes.
August 25, 2009 at 11:18 am
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| | Force generation and protease gene expression in organotypic co-cultures of fibroblasts and keratinocytes. J Tissue Eng Regen Med. 2009 Aug 21; Authors: Wall IB, Bhadal N, Broad S, Whawell SA, Mudera V, Lewis MP Fibroblast-epithelium interactions are crucial for successful tissue engineering of skin and oral mucosal equivalents. In this study, we assessed early force generation in organotypic fibroblast-epithelium co-cultures, using normal human keratinocytes (NHK) and HPV16-transformed (UP) cells. During the initial 2 h period, organotypic co-cultures containing both epithelial cell types produced significantly more force than fibroblasts alone (p < 0.05). After 2 h, the epithelial contribution became diminished and did not significantly contribute to intrinsic force generation by fibroblasts, and no differences were observed when using UP vs. NHK. We then measured protease gene expression at the end of the experimental period. Distinct differences were evident in protease expression both between NHK-human skin fibroblast (HSF) vs. UP-HSF co-cultures and compared to fibroblasts alone. We conclude that whilst the very early contractile response of fibroblasts is enhanced by the overlying epithelium, this becomes diminished as the fibroblast response becomes predominant and it does contribute to tissue remodelling via regulation of protease expression. Copyright (c) 2009 John Wiley & Sons, Ltd. PMID: 19701934 [PubMed - as supplied by publisher] |
| Tracking large solid constructs suspended in a rotating bioreactor: A combined experimental and theoretical study.
August 25, 2009 at 11:18 am
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| | Tracking large solid constructs suspended in a rotating bioreactor: A combined experimental and theoretical study. Biotechnol Bioeng. 2009 Aug 21; Authors: Cummings LJ, Sawyer NB, Morgan SP, Rose FR, Waters SL We present a combined experimental and theoretical study of the trajectory of a large solid cylindrical disc suspended within a fluid-filled rotating cylindrical vessel. The experimental set-up is relevant to tissue-engineering applications where a disc-shaped porous scaffold is seeded with cells to be cultured, placed within a bioreactor filled with nutrient-rich culture medium, which is then rotated in a vertical plane to keep the growing tissue construct suspended in a state of "free fall".The experimental results are compared with theoretical predictions based on the model of Cummings ' Waters (2007), who showed that the suspended disc executes a periodic motion. For anticlockwise vessel rotation three regimes were identified: (i) disc remains suspended at a fixed position on the right-hand side of the bioreactor; (ii) disc executes a periodic oscillatory motion on the right-hand side of the bioreactor; (iii) disc orbits the bioreactor. All three regimes are captured experimentally, and good agreement between theory and experiment is obtained. For the tissue engineering application computation of the fluid dynamics allows the nutrient concentration field surrounding a tissue construct (a property that cannot be measured experimentally) to be determined (Cummings ' Waters 2007). The implications for experimental cell-culture protocols are discussed. (c) 2009 Wiley Periodicals, Inc. PMID: 19701926 [PubMed - as supplied by publisher] |
| Biomimetic Ca-P coatings incorporating bisphosphonates produced on starch-based degradable biomaterials.
August 25, 2009 at 11:18 am
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| | Biomimetic Ca-P coatings incorporating bisphosphonates produced on starch-based degradable biomaterials. J Biomed Mater Res B Appl Biomater. 2009 Aug 21; Authors: Oliveira AL, Pedro AJ, Arroyo CS, Mano JF, Rodriguez G, Roman JS, Reis RL In this study, sodium clodronate, a well-known therapeutic agent from the family of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating, previously formed on the surface of a starch-based biomaterial by a sodium silicate methodology, as a strategy to develop a site-specific drug delivery system for bone tissue regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the release profiles of sodium clodronate was also assessed. As a preliminary approach, this first study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic cell line since there is still little information available on the interaction between BPs and this type of cells. Sodium clodronate was successfully incorporated, at different doses, in the structure of a biomimetic CaP layer previously formed by a sodium silicate process. This type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be produced on the surface of degradable polymers and then used for regulating the equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect at the interface between the biomaterial and bone. (c) 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009. PMID: 19701915 [PubMed - as supplied by publisher] |
| Fibrin glue in ophthalmology.
August 25, 2009 at 11:18 am
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| | Fibrin glue in ophthalmology. Indian J Ophthalmol. 2009 Sep-Oct;57(5):371-9 Authors: Panda A, Kumar S, Kumar A, Bansal R, Bhartiya S Suturing is a time consuming task in ophthalmology and suture induced irritation and redness are frequent problems. Postoperative wound infection and corneal graft rejection are examples of possible suture related complications. To prevent these complications, ophthalmic surgeons are switching to sutureless surgery. A number of recent developments have established tissue adhesives like cyanoacrylate glue and fibrin glue as attractive alternatives to sutures. A possible and promising new application for tissue adhesives is to provide a platform for tissue engineering. Currently, tissue glue is being used for conjunctival closure following pterygium and strabismus surgery, forniceal reconstruction surgery, amniotic membrane transplantation, lamellar corneal grafting, closure of corneal perforations and descematoceles, management of conjunctival wound leaks after trabeculectomy, lid surgery, adnexal surgery and as a hemostat to minimise bleeding. The purpose of this review is to discuss the currently available information on fibrin glue. PMID: 19700876 [PubMed - in process] |
| Controlled and Extended Drug Release Behavior of Chitosan-Based Nanoparticle Carrier.
August 25, 2009 at 11:18 am
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| | Controlled and Extended Drug Release Behavior of Chitosan-Based Nanoparticle Carrier. Acta Biomater. 2009 Aug 20; Authors: Yuan Q, Shah J, Hein S, Misra RD Controlled drug release is presently gaining significant attention. In this regard, we describe here the synthesis (based on the understanding of chemical structure), structural morphology, swelling behavior, and drug release response of chitosan intercalated in an expandable layered aluminosilicate. In contrast to pure chitosan, where there is a continuous increase in drug release with time, the chitosan-aluminosilicate nanocomposite carrier was characterized by controlled and extended release. The drug release from the nanocomposite particle carrier occurs by the degradation of nanocomposite particle carrier to individual components or nanostructures with different composition. In both layered aluminosilicate-based mineral and chitosan-aluminosilicate nanocomposite carrier, the investigated positively-charged chemotherapeutic drug strongly binds to the negatively charged aluminosilicate and the release of drug is slow. Furthermore, the drug release pattern of chitosan-aluminosilicate nanocomposite carrier is affected by pH and the chitosan/aluminosilicate ratio. The study points toward the potential application of hybrid nanocomposite carrier in biomedical applications including tissue engineering and controlled drug delivery. PMID: 19699817 [PubMed - as supplied by publisher] |
| Partially nanofibrous architecture of 3D tissue engineering scaffolds.
August 25, 2009 at 11:18 am
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| | Partially nanofibrous architecture of 3D tissue engineering scaffolds. Biomaterials. 2009 Aug 20; Authors: Wei G, Ma PX An ideal tissue-engineering scaffold should provide suitable pores and appropriate pore surface to induce desired cellular activities and to guide 3D tissue regeneration. In the present work, we have developed macroporous polymer scaffolds with varying pore wall architectures from smooth (solid), microporous, partially nanofibrous, to entirely nanofibrous ones. All scaffolds are designed to have well-controlled interconnected macropores, resulting from leaching sugar sphere template. We examine the effects of material composition, solvent, and phase separation temperature on the pore surface architecture of 3D scaffolds. In particular, phase separation of PLLA/PDLLA or PLLA/PLGA blends leads to partially nanofibrous scaffolds, in which PLLA forms nanofibers and PDLLA or PLGA forms the smooth (solid) surfaces on macropore walls, respectively. Specific surface areas are measured for scaffolds with similar macroporosity but different macropore wall architectures. It is found that the pore wall architecture predominates the total surface area of the scaffolds. The surface area of a partially nanofibrous scaffold increases linearly with the PLLA content in the polymer blend. The amounts of adsorbed proteins from serum increase with the surface area of the scaffolds. These macroporous scaffolds with adjustable pore wall surface architectures may provide a platform for investigating the cellular responses to pore surface architecture, and provide us with a powerful tool to develop superior scaffolds for various tissue-engineering applications. PMID: 19699518 [PubMed - as supplied by publisher] |
| A molecularly defined array based on native fibrillar collagen for the assessment of skin tissue engineering biomaterials.
August 25, 2009 at 11:18 am
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| | A molecularly defined array based on native fibrillar collagen for the assessment of skin tissue engineering biomaterials. Biomaterials. 2009 Aug 20; Authors: Lammers G, Tjabringa GS, Schalkwijk J, Daamen WF, van Kuppevelt TH Large-scale in vivo evaluation of biomaterials is time-consuming and limited by ethical considerations. The availability of a library of biomaterials would allow a fast and rational in vitro selection of those biomaterials to be evaluated in vivo. For this reason, we developed an array of 48 different, molecularly-defined films based on native fibrillar collagen. The films differed in the type and amount of extracellular matrix components (type I/IV collagens, fibrous/solubilised elastin, glycosaminoglycans, heparin, chondroitin sulfate or dermatan sulfate), method of preparation (homogenisation) and method and extent of crosslinking (carbodiimide (EDC/NHS) or glutaraldehyde). The array was evaluated by studying morphology, proliferation and differentiation of primary human keratinocytes/fibroblasts. Major differences were observed. Only a small selection of films (especially those containing elastin fibres) specifically stimulated the proliferation of keratinocytes, but not fibroblasts. Such films may be the biomaterials of choice for in vivo evaluation for skin tissue engineering and regenerative medicine. PMID: 19699517 [PubMed - as supplied by publisher] |
| In situ gelling properties of chitosan-thioglycolic acid conjugate in the presence of oxidizing agents.
August 25, 2009 at 11:18 am
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| | In situ gelling properties of chitosan-thioglycolic acid conjugate in the presence of oxidizing agents. Biomaterials. 2009 Aug 20; Authors: Sakloetsakun D, Hombach JM, Bernkop-Schnürch A The rheological behaviour of chitosan-thioglycolic acid conjugate (chitosan-TGA) in the presence of four oxidizing agents was investigated. Chitosan-TGA was synthesized via amide bond formation between the primary amino group of chitosan and the carboxylic acid group of thioglycolic acid. The sol-gel phase transition of the polymer was determined by rheological measurements. Moreover, cytotoxicity of the gel in combination with each oxidizing agent was evaluated utilizing LDH and MTT assay. The modified chitosan displayed 1053+/-44mumol/g thiol groups. Results of rheological studies showed that 1% (m/v) chitosan-TGA without any oxidizing agents became gel within 40min. In contrast, when the oxidizing agents hydrogen peroxide, sodium periodate, ammonium persulfate and sodium hypochlorite were added, respectively, gelation took place within a few minutes. Within 20min, hydrogen peroxide having been added in a final concentration of 25.2nmol/L increased dynamic viscosity of 1% (m/v) chitosan-TGA up to 16,500-fold. This can be explained by the formation of inter- and/or intramolecular disulfide bonds which were indirectly verified via the decrease in thiol groups. Additionally, evidence of an increase in cross-linking of thiolated chitosan as a function of time was provided by frequency sweep measurements. Furthermore, viability of Caco-2 cells having been incubated with chitosan-TGA/oxidizing agent systems assessed by MTT assay was 70-85% and the percentage of LDH release was only in case of the chitosan-TGA/ammonium persulfate system significantly (p<0.05) raising compared to the negative control. According to these results, chitosan-TGA/oxidizing agent combinations might be a promising novel in situ gelling system for various pharmaceutical applications such as a controlled drug release carrier or for tissue engineering. PMID: 19699516 [PubMed - as supplied by publisher] |
| "Linear" Shear Conditioning Improves Vascular Graft Retention of Adipose-Derived Stem Cells by Up-regulation of the alpha5beta1 Integrin.
August 25, 2009 at 11:18 am
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| | "Linear" Shear Conditioning Improves Vascular Graft Retention of Adipose-Derived Stem Cells by Up-regulation of the alpha5beta1 Integrin. Tissue Eng Part A. 2009 Aug 21; Authors: McIlhenny SE, Hager ES, Grabo DJ, Dimatteo C, Shapiro IM, Tulenko TN, Dimuzio PJ Use of adult adipose-derived stem cells (ASC) as endothelial cell (EC) substitutes in vascular tissue engineering is attractive due to their availability. However, when seeded onto decellularized vascular scaffolding and exposed to physiological fluid shear force, ASC are physically separated from the graft lumen. Herein we have investigated methods of increasing initial ASC attachment using luminal pre-coats and a novel protocol for the gradual introduction of shear stress optimizing ASC retention. Fibronectin coating of the graft lumen increased ASC attachment by nearly six-fold compared to negative controls. Gradual introduction of fluid shear stress using a novel bioreactor whereby flow rate was increased every second at a rate of 1.5 dynes/cm2 per day resulted in complete luminal coverage compared to near complete cell loss following conventional daily abrupt increases. An up-regulation of the alpha5beta1 integrin was evinced following shear stress exposure, which accounts for the observed increase in ASC retention on the graft lumen. These results indicate a novel method for the seeding, conditioning, and retaining of adult stem cells on a decellularized vein scaffold within a high shear stress microenvironment. PMID: 19698069 [PubMed - as supplied by publisher] |
| Challenges in Cardiac Tissue Engineering.
August 25, 2009 at 11:18 am
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| | Challenges in Cardiac Tissue Engineering. Tissue Eng Part B Rev. 2009 Aug 21; Authors: Vunjak-Novakovic G, Tandon N, Godier A, Maidhof R, Marsano A, Martens T, Radisic M Cardiac tissue engineering aims to create functional tissue constructs that can re-establish the structure and function of injured myocardium. Engineered constructs can also serve as high-fidelity models for studies of cardiac development and disease. In a general case, the biological potential of the cell - the actual "tissue engineer" - is mobilized by providing highly controllable three-dimensional environments that can mediate cell differentiation and functional assembly. For cardiac regeneration, some of the key requirements that need to be met are the selection of a human cell source, establishment of cardiac tissue matrix, electromechanical cell coupling, robust and stable contractile function, and functional vascularization. We review here the potential and challenges of cardiac tissue engineering for developing therapies that could prevent or reverse heart failure. PMID: 19698068 [PubMed - as supplied by publisher] |
| Icariin: A Potential Osteoinductive Compound for Bone Tissue Engineering.
August 25, 2009 at 11:18 am
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| | Icariin: A Potential Osteoinductive Compound for Bone Tissue Engineering. Tissue Eng Part A. 2009 Aug 21; Authors: Zhao J, Ohba S, Komiyama Y, Shinkai M, Chung UI, Nagamune T To effectively treat bone diseases using bone regenerative medicine, there is an urgent need to develop safe and cheap drugs that can potently induce bone formation. Here, we demonstrate the osteogenic effects of icariin, the main active compound of Epimedium pubescens. Icariin induced osteogenic differentiation of pre-osteoblastic cells. The combination of icariin and a helioxanthin-derived small compound synergistically induced osteogenic differentiation of MC3T3-E1 cells to a similar extent to bone morphogenetic protein (BMP)-2. Icariin enhanced the osteogenic induction activity of BMP-2 in a fibroblastic cell line. Mineralization was enhanced by treatment with a combination of icariin and calcium-enriched medium. The in vivo anabolic effect of icariin was confirmed in a mouse calvarial defect model. Eight-week-old male C57BL/6N mice were transplanted with icariin-calcium phosphate cement (CPC) tablets or CPC tablets only (n=5 for each), and bone regeneration was evaluated after 4 and 6 weeks. Significant new bone formation was observed in the icariin-CPC group at 4 weeks and the new bone thickness had increased by 6 weeks. Obvious blood vessel formation was observed in the icariin-induced new bone. Treatment of senescence-accelerated mouse prone 1 and senescence-accelerated mouse prone 6 models further demonstrated that icariin was able to enhance bone formation in vivo. Therefore, icariin is a strong candidate for an osteogenic compound for use in bone tissue engineering. PMID: 19698057 [PubMed - as supplied by publisher] |
| Translational Models for Studying Meniscal Repair and Replacement: What they can and cannot tell us.
August 25, 2009 at 11:18 am
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| | Translational Models for Studying Meniscal Repair and Replacement: What they can and cannot tell us. Tissue Eng Part B Rev. 2009 Aug 21; Authors: Arnoczky SP, Cook JL, Carter T, Turner S Advances in clinical practice often have their roots in basic science investigations that provide the "proof of principle" of the treatment concept in question. However, if these concepts are to become reality, they first must be tested in translational animal models to confirm both safety and efficacy. The need to identify appropriate translational models in musculoskeletal tissue engineering and regenerative repair is of critical importance. This is especially true in meniscal research, where the functional anatomy of the structure is directly related to its contribution to the complex biomechanics of the joint and its role in chondroprotection. While no one animal model has established itself as the most appropriate for all aspects of meniscal research several species have been used to successfully test specific hypotheses. A careful and comprehensive comparison must always be done to validate the utility of a specific animal model. Therefore, it is the purpose of this article to provide an overview of the considerations involved when selecting a translational model for meniscal research. PMID: 19698055 [PubMed - as supplied by publisher] |
| Phosphatase actions at the site of appositional mineralization in bisphosphonate-affected bones of the rat.
August 25, 2009 at 11:18 am
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| | Phosphatase actions at the site of appositional mineralization in bisphosphonate-affected bones of the rat. J Med Dent Sci. 2008 Sep;55(3-4):255-65 Authors: Li Y, Nakayama H, Notani T, Ahmad M, Tabata MJ, Takano Y Tissue-nonspecific alkaline phosphatase (TNSALP) and Ca-ATPase are known to play roles in bone mineralization, but how these enzymes contribute to appositional mineralization has been illusive. Here we examined the active sites of these enzymes in appositional mineralization using the bones of young rats being administered with 1-hydroxyethylidene-1,1-bisphosphonate (HEBP) for 5 days. The doses of HEBP totally abolished mineralization of newly formed bone matrix except in matrix vesicles (MVs), and hence allowed precise localization of MVs and phosphatase reactions within non-mineralized extracellular matrix. Intense TNSALP and ATPase reactions were confirmed along the limited portions of osteoblast membranes where intimate cell-cell contacts were maintained. Diffuse reactions of these enzymes were throughout the osteoid implicating efflux of TNSALP and ATPase molecules into extracellular matrix from the osteoblast membranes. Phosphatase reactions associated with MVs varied both in intensity and location among the individual vesicles; newly formed MVs were almost free of reactions but appeared to gain those activities later in the osteoid. These data suggest that TNSALP and ATPase are released from the osteoblast membrane and later integrated into MVs within the osteoid. The osteoblasts may thus regulate appositional mineralization of bone from a distance at least in part by providing phosphatases via MVs. PMID: 19697513 [PubMed - in process] |
| Inkjet printing of laminin gradient to investigate endothelial cellular alignment.
August 25, 2009 at 11:18 am
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| | Inkjet printing of laminin gradient to investigate endothelial cellular alignment. Colloids Surf B Biointerfaces. 2009 Sep 1;72(2):230-5 Authors: Cai K, Dong H, Chen C, Yang L, Jandt KD, Deng L To investigate the influence of the protein surface-density gradient on endothelial cell alignment, a novel approach for the fabrication of a laminin gradient on gold-coated substrates has been developed in this study. Our approach involves programmed inkjet printing of an alkanethiol (11-mercaptoundecanoic acid, C(10)COOH, MUA) gradient onto gold-coated substrates, followed by backfilling with 11-mercapto-1-undecanol (C(11)OH, MUD). The -COOH moieties were activated and then covalently linked with laminin. This treatment led to a surface-density gradient of laminin. Contact angle measurement, X-ray photoelectron spectroscopy (XPS) and fluorescence microscopy were employed to characterize the self-assembled monolayers (SAMs) and protein gradient, respectively. Results proved the feasibility of the fabrication of a protein gradient by using the inkjet printing technique. The self-assembled monolayer gradients displayed a high packing density, as indicated by dynamic contact angle measurement. More importantly, the gradient slope was easily tunable over a significant distance from 20 to 30 mm. The laminin gradient was clearly visible by fluorescence microscopy observation. Endothelial cells cultured on the surface-density gradient of laminin demonstrated a strong alignment tendency in parallel to the gradient. The higher the laminin density the more cells were observed. The result indicates that cell attachment is dependent on the surface density of laminin. This work broadens our methodology to investigate chemical stimuli-induced cell directional alignment. It is potentially important for understanding cell alignment/ingrowth behavior for angiogenesis and implant technology including tissue-engineered structures. PMID: 19419847 [PubMed - indexed for MEDLINE] | | | 
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