| Differential expression of a novel gene BRE (TNFRSF1A modulator/BRCC45) in response to stress and biological signals.
September 17, 2009 at 7:49 am
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| | Differential expression of a novel gene BRE (TNFRSF1A modulator/BRCC45) in response to stress and biological signals. Mol Biol Rep. 2009 Sep 16; Authors: Chan JY, Li L, Miao J, Cai DQ, Lee KK, Chui YL Stress-responsive genes play critical roles in many biological functions that includes apoptosis, survival, differentiation and regeneration. We have identified a novel stress-responsive gene called BRE which interacts with TNF-receptor-1 and blocks the apoptotic effect of TNF-alpha. BRE enhances tumor growth in vivo and is up-regulated in hepatocellular and esophageal carcinomas. BRE also regulates the ubiquitination of the DNA repair complex BRCC, and the synthesis of steroid hormones. Here, we examined BRE-mRNA in cells after treatments with UV and ionizing radiation (IR). UV and IR treatment alone suppressed BRE-mRNA levels by more than 90% at 24 h, while hydroxyurea, fluorodeoxyuridine, aphidicolin, known inhibitors of S-phase DNA synthesis, had no significant effect. BRE protein expression was unaltered in cells treated with TNF-alpha, Interleukin-1 and Dexamethasone, while a threefold increase was observed following chorionic gonadotropin exposure. Although BRE plays a regulatory role in many different pathways, yet its expression is apparently under very stringent control. PMID: 19757177 [PubMed - as supplied by publisher] |
| Spray-spinning: a novel method for making alginate/chitosan fibrous scaffold.
September 17, 2009 at 7:49 am
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| | Spray-spinning: a novel method for making alginate/chitosan fibrous scaffold. J Mater Sci Mater Med. 2009 Sep 16; Authors: Wang JZ, Huang XB, Xiao J, Li N, Yu WT, Wang W, Xie WY, Ma XJ, Teng YL The subject of our investigations was the process of obtaining alginate/chitosan polyelectrolyte complex (PEC) fibers. In this study, a novel method named "spray-spinning" was developed for the making of these hybrid fibers. In spray-spinning, a chitosan solution was sprayed into a flowing sodium alginate solution and sheared into streamlines. The elongated streamlines subsequently transformed into alginate/chitosan PEC fibers. Average diameter of the fibers increased with the increasing of chitosan concentration used in spinning. The fibers showed a high water-absorbability of about 45 folds of water to their dry weight and retained their integrity after incubation in Minimum Essential Medium (MEM) for up to 30 days. In vitro co-culture experiments indicated that the fibers could support the three-dimensional growth of HepG2 cells and did not display any cyto-toxicity. Moreover, in vivo implanting experiments indicated that the connective tissue cells infiltrated into the implanted fibrous scaffolds in 3 weeks after surgery. These results demonstrated the potential applications of the as-spun fibers in regenerative medicine and tissue engineering. PMID: 19756966 [PubMed - as supplied by publisher] |
| Variable optimization for the formation of three-dimensional self-organized heart muscle.
September 17, 2009 at 7:49 am
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| | Variable optimization for the formation of three-dimensional self-organized heart muscle. In Vitro Cell Dev Biol Anim. 2009 Sep 15; Authors: Khait L, Hodonsky CJ, Birla RK Cardiac tissue-engineering research is focused on the development of functional three-dimensional (3D) heart muscle in vitro. These models allow the detailed study of critical events in organogenesis, such as the establishment of cell-cell communication and construction and modification of the extracellular matrix. We have previously described a model for 3D heart muscle, termed cardioids, formed by the spontaneous delamination of a cohesive monolayer of primary cells in the absence of any synthetic scaffolding material. In an earlier publication, we have shown that, upon electrical stimulation, cardioids generate a twitch force in the range of 200-300 microN, generate a specific force (twitch force normalized to total cross-sectional area) of 2-4 kN/m(2), and can be electrically paced at frequencies of up to 10 Hz without any notable fatigue. We have two objectives for the current study: model development and model optimization. Our model development efforts are focused on providing additional characterization of the cardioid model. In this study, we show for the first time that cardioids show a pattern of gene expression comparable to that of cells cultured in two dimensions on tissue culture plastic and normal mammalian heart muscle. Compared with primary cardiac cells cultured on tissue culture plastic, the expression of alpha-myosin heavy chain (MHC), beta-MHC, SERCA2, and phospholamban was significantly higher in cardioids. Our second objective, model optimization, is focused on evaluating the effect of several cell culture variables on cardioid formation and function. Specifically, we looked at the effect of plating density (1.0-4.0 x 10(6) cells per cardioid), concentration of two adhesion proteins (laminin at 0.2-2.0 microg/cm(2) and fibronectin at 1-10 microg/cm(2)), myocyte purity (using preplating times of 15 and 60 min), and ascorbic acid stimulation (1-100 microl/ml). For our optimization studies, we utilized twitch force in response to electrical stimulation as our endpoint metric. Based on these studies, we found that cardioids formed with a plating density in the range 3-4 x 10(6) cells per cardioid generated the maximum twitch force, whereas increasing the surface adhesion protein (using either laminin or fibronectin) and increasing the myocyte purity both resulted in a decrease in twitch force. In addition, increasing the ascorbic acid concentration resulted in an increase in the baseline force of cardioids, which was recorded in the absence of electrical stimulation. Based on the model development studies, we have shown that cardioids do indeed exhibit a gene expression pattern similar to normal mammalian heart muscle. This provides further validity for the cardioid model. Based on the model optimization studies, we have identified specific cell culture regimes which support cardioid formation and function. These results are specific to the cardioid model; however, they may be translated and applied to other tissue-engineering models. Collectively, the work described in this study provides insight into the formation of functional 3D heart muscle and the effect of several cell culture variables on tissue formation and function. PMID: 19756885 [PubMed - as supplied by publisher] |
| [Tissue engineering of bone tissue : Principles and clinical applications.]
September 17, 2009 at 7:49 am
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| | [Tissue engineering of bone tissue : Principles and clinical applications.] Unfallchirurg. 2009 Sep;112(9):785-95 Authors: Schmidt-Rohlfing B, Tzioupis C, Menzel CL, Pape HC Complex fractures are still a major clinical challenge. The treatment options of large bony defects either with autografts or allografts are limited in terms of material availability and tissue in-growth. Tissue engineering might offer a solution to this problem. In an interdisciplinary approach artificial bony tissue can be generated which mimics normal bone in terms of function and morphology. So far tissue engineering of bone is mainly confined to laboratory investigations whereas clinical applications are still in the beginning. This manuscript presents the most important scaffolds as well as growth factors and cell systems. Furthermore, it focuses on clinical studies for the treatment of large bony defects using tissue engineered cell-matrix constructs. PMID: 19756458 [PubMed - in process] |
| Strategies for Therapeutic Repair: The "R" Regenerative Medicine Paradigm.
September 17, 2009 at 7:49 am
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| | Strategies for Therapeutic Repair: The "R" Regenerative Medicine Paradigm. Clin Transl Sci. 2008 Sep 10;1(2):168-171 Authors: Nelson TJ, Behfar A, Terzic A Beyond the palliative reach of today, medical therapies of tomorrow aim to treat the root cause of chronic degenerative diseases. Therapeutic repair encompasses the converging triad of rejuvenation, regeneration or replacement strategies that rely on self-healing processes, stem cell regeneration, and/or organ transplantation. Natural healing or rejuvenation exemplify inherent, baseline repair secured by tissue self-renewal and de novo cell biogenesis, particularly effective in organs with a high endogenous reparative capacity. Transplant medicine exploits the replacement strategy as a valuable option to recycle used parts and restore failing organ function by means of exogenous substitutes-it is, however, limited by donor shortage. Stem cell-based regeneration offers the next frontier of medical therapy through delivery of essentially unlimited pools of autologous or allogeneic, naive or modified, progenitor cells to achieve structural and functional repair. Translation into clinical applications requires the establishment of a regenerative medicine community of practice capable to bridge discovery with personalized treatment solutions. Indeed, this multidisciplinary specialized workforce will be capable to integrate the new science of embryology, immunology, and stem cell biology into bioinformatics and network medicine platforms, ensuring implementation of therapeutic repair strategies into individualized disease management algorithms. PMID: 19756244 [PubMed - as supplied by publisher] |
| Cryo-Imaging of Fluorescently-Labeled Single Cells in a Mouse.
September 17, 2009 at 7:49 am
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| | Cryo-Imaging of Fluorescently-Labeled Single Cells in a Mouse. Proc Soc Photo Opt Instrum Eng. 2009 Jan 1;7262:72620W-72620W8 Authors: Steyer GJ, Roy D, Salvado O, Stone ME, Wilson DL We developed a cryo-imaging system to provide single-cell detection of fluorescently labeled cells in mouse, with particular applicability to stem cells and metastatic cancer. The Case cryo-imaging system consists of a fluorescence microscope, robotic imaging positioner, customized cryostat, PC-based control system, and visualization/analysis software. The system alternates between sectioning (10-40 mum) and imaging, collecting color brightfield and fluorescent block-face image volumes >60GB. In mouse experiments, we imaged quantum-dot labeled stem cells, GFP-labeled cancer and stem cells, and cell-size fluorescent microspheres. To remove subsurface fluorescence, we used a simplified model of light-tissue interaction whereby the next image was scaled, blurred, and subtracted from the current image. We estimated scaling and blurring parameters by minimizing entropy of subtracted images. Tissue specific attenuation parameters were found [u(T) : heart (267 +/- 47.6 mum), liver (218 +/- 27.1 mum), brain (161 +/- 27.4 mum)] to be within the range of estimates in the literature. "Next image" processing removed subsurface fluorescence equally well across multiple tissues (brain, kidney, liver, adipose tissue, etc.), and analysis of 200 microsphere images in the brain gave 97+/-2% reduction of subsurface fluorescence. Fluorescent signals were determined to arise from single cells based upon geometric and integrated intensity measurements. Next image processing greatly improved axial resolution, enabled high quality 3D volume renderings, and improved enumeration of single cells with connected component analysis by up to 24%. Analysis of image volumes identified metastatic cancer sites, found homing of stem cells to injury sites, and showed microsphere distribution correlated with blood flow patterns.We developed and evaluated cryo-imaging to provide single-cell detection of fluorescently labeled cells in mouse. Our cryo-imaging system provides extreme (>60GB), micron-scale, fluorescence, and bright field image data. Here we describe our image pre-processing, analysis, and visualization techniques. Processing improves axial resolution, reduces subsurface fluorescence by 97%, and enables single cell detection and counting. High quality 3D volume renderings enable us to evaluate cell distribution patterns. Applications include the myriad of biomedical experiments using fluorescent reporter gene and exogenous fluorophore labeling of cells in applications such as stem cell regenerative medicine, cancer, tissue engineering, etc. PMID: 19756213 [PubMed - as supplied by publisher] |
| "Opening" the mesenchymal stem cell tool box.
September 17, 2009 at 7:49 am
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| | "Opening" the mesenchymal stem cell tool box. Eur J Dent. 2009 Jul;3(3):240-9 Authors: Zeidán-Chuliá F, Noda M Adult mesenchymal stem cells (MSCs) are adherent stromal cells able to self-renew and differentiate into a wide variety of cells and tissues. MSCs can be obtained from distinct tissue sources and have turned out to be successfully manipulated in vitro. As adult stem cells, MSCs are less tumorigenic than their embryonic correlatives and posses another unique characteristic which is their almost null immunogenicity. Moreover, these cells seem to be immunosuppressive in vitro. These facts together with others became MSCs a promising subject of study for future approaches in bioengineering and cell-based therapy. On the other hand, new strategies to achieve long-term integration as well as efficient differentiation of these cells at the area of the lesion are still challenging, and the signalling pathways ruling these processes are not completely well characterized. In this review, we are going summarize the general landscape and current status of the MSC tool as well as their wide potential in tissue engineering, from neuronal to tooth replacement. Highlights and pitfalls for further clinical applications will be discussed. PMID: 19756201 [PubMed - in process] |
| 2007 AIChE Alpha Chi Sigma Award: From Material to Tissue: Biomaterial Development, Scaffold Fabrication, and Tissue Engineering.
September 17, 2009 at 7:49 am
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| | 2007 AIChE Alpha Chi Sigma Award: From Material to Tissue: Biomaterial Development, Scaffold Fabrication, and Tissue Engineering. AIChE J. 2008 Oct 29;54(12):3048-3067 Authors: Kretlow JD, Mikos AG The need for techniques to facilitate the regeneration of failing or destroyed tissues remains great with the aging of the worldwide population and the continued incidence of trauma and diseases such as cancer. A 16-year history in biomaterial scaffold development and tissue engineering is examined, beginning with the synthesis of novel materials and fabrication of 3D porous scaffolds. Exploring cell-scaffold interactions and subsequently cellular delivery using biomaterial carriers, we have developed a variety of techniques for bone and cartilage engineering. In addition to delivering cells, we have utilized growth factors, DNA, and peptides to improve the in vitro and in vivo regeneration of tissues. This review covers important developments and discoveries within our laboratory, and the increasing breadth in the scope of our work within the expanding field of tissue engineering is presented. PMID: 19756176 [PubMed - as supplied by publisher] |
| TC-PTP is required for the maintenance of MYC-driven B-cell lymphomas.
September 17, 2009 at 7:49 am
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| | TC-PTP is required for the maintenance of MYC-driven B-cell lymphomas. Blood. 2009 Sep 15; Authors: Young RM, Polsky A, Refaeli Y We sought to determine the contributions of protein tyrosine phosphatases (PTPs) to the pathogenesis of B-cell lymphomas. We found that T-cell PTP (TC-PTP) was overexpressed in transformed B-cells. We hypothesized that TC-PTP may be a tumor promoting gene that is regulated by MYC overexpression in B-cells. Knockdown of TC-PTP in murine tumors resulted in decreased cell viability in vitro due to an arrest in the G1 phase of the cell cycle. Furthermore, cells with reduced TC-PTP expression were unable to either engraft or expand in vivo. Taken together, these data indicate that TC-PTP is required for B-cell tumor maintenance. Our data also suggested a correlation between TC-PTP expression and MYC overexpression. To investigate this further, we used malignant murine B-cells that contain a doxycycline-repressible MYC transgene. We found that repression of MYC overexpression with doxycycline reduced TC-PTP expression. Moreover, enforced expression of TC-PTP showed partial rescue of the expansion of tumor cells following suppression of MYC overexpression. These results suggest that MYC overexpression induces TC-PTP overexpression, which in turn promotes tumor proliferation, implicating TC-PTP as an important effector of the MYC-driven proliferation program in B-cell lymphomas. Thus, TC-PTP may be a suitable molecular target for the treatment of B-cell lymphomas. PMID: 19755676 [PubMed - as supplied by publisher] |
| Genes and Signals Regulating Murine Trophoblast Cell Development.
September 17, 2009 at 7:49 am
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| | Genes and Signals Regulating Murine Trophoblast Cell Development. Mech Dev. 2009 Sep 12; Authors: El-Hashash AH, Warburton D, Kimber SJ A fundamental step in embryonic development is cell differentiation whereby highly specialised cell types are developed from a single undifferentiated, fertilised egg. One of the earliest lineages to form in the mammalian conceptus is the trophoblast, which contributes exclusively to the extraembryonic structures that form the placenta. Trophoblast giant cells (TGCs) in the rodent placenta form the outermost layer of the extraembryonic compartment, establish direct contact with maternal cells, and produce a number of pregnancy-specific cytokine hormones. Giant cells differentiate from proliferative trophoblasts as they exit the cell cycle and enter a genome-amplifying endocycle. Normal differentiation of secondary TGCs is a critical step toward the formation of the placenta and normal embryonic development. Trophoblast development is also of particular interest to the developmental biologist and immunobiologist, as they constitute the immediate cellular boundary between the embryonic and maternal tissues. Abnormalities in the development of secondary TGCs results in severe malfunction of the placenta. Herein we review new information that has been accumulated recently regarding the molecular and cellular regulation of trophoblast and placenta development. In particular, we discuss the molecular aspects of murine TGC differentiation. We also focus on the role of growth and transcription factors in TGC development. PMID: 19755154 [PubMed - as supplied by publisher] |
| Nonexploratory Movement and Behavioral Alterations in a Thalidomide or Valproic Acid-induced Autism Model Rat.
September 17, 2009 at 7:49 am
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| | Nonexploratory Movement and Behavioral Alterations in a Thalidomide or Valproic Acid-induced Autism Model Rat. Neurosci Res. 2009 Sep 12; Authors: Narita M, Oyabu A, Imura Y, Kamada N, Yokoyama T, Tano K, Uchida A, Narita N Autism is a behaviorally characterized disorder with impairments in social interactions, as well as stereotyped, repetitive patterns of behaviors and interests. Exposure of rat fetuses to thalidomide (THAL) or valproic acid (VPA) on the ninth day of gestation has been reported as a useful model for human autism. We have shown that early serotonergic neural development is disrupted in these rats. In the current study, we used a radial maze and open field experimental paradigm to investigate whether these rats present behavioral and/or learning aberrations. THAL (500mg/kg), VPA (800mg/kg), or vehicle was administered orally to E9 pregnant rats at 7-10 weeks of age. Although the mean number of correct and incorrect arm choices in the initial eight arm choices did not differ between control and teratogen-exposed groups, achievement of learning (seven or eight consecutive correct choices for 3 consecutive days for individual rats) seemed to be impaired in teratogen-exposed groups. Interestingly, average time to explore the maze task was shorter in the teratogen-exposed groups, indicating that correct choice might be due to mere coincidence (i.e.; nonexploratory movement). Unexpectedly, no significant differences were observed in social interaction in these rats. These results indicate that prenatal exposure to THAL and VPA might alter behavior in a manner that is, in part, consistent with human autism. PMID: 19755133 [PubMed - as supplied by publisher] |
| Neural Network Analysis Identifies Scaffold Properties Necessary for In Vitro Chondrogenesis in Elastin-like Polypeptide Biopolymer Scaffolds.
September 17, 2009 at 7:49 am
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| | Neural Network Analysis Identifies Scaffold Properties Necessary for In Vitro Chondrogenesis in Elastin-like Polypeptide Biopolymer Scaffolds. Tissue Eng Part A. 2009 Sep 15; Authors: Nettles DL, Haider MA, Chilkoti A, Setton LA The successful design of biomaterial scaffolds for articular cartilage tissue engineering requires an understanding of the impact of combinations of material formulation parameters on diverse and competing functional outcomes of biomaterial performance. This study sought to explore the use of a type of unsupervised artificial network, a self-organizing map, to identify relationships between scaffold formulation parameters (crosslink density, molecular weight, and concentration) and 11 such outcomes (including mechanical properties, matrix accumulation, metabolite usage and production, and histological appearance) for scaffolds formed from crosslinked elastin-like polypeptide (ELP) hydrogels. The artificial neural network recognized patterns in functional outcomes and provided a set of relationships between ELP formulation parameters and measured outcomes. Mapping resulted in the best mean separation amongst neurons for mechanical properties and pointed to crosslink density as the strongest predictor of most outcomes, followed by ELP concentration. The map also grouped formulations together that simultaneously resulted in the highest values for matrix production, greatest changes in metabolite consumption or production, and highest histological scores, indicating that the network was able to recognize patterns amongst diverse measurement outcomes. These results demonstrated the utility of artificial neural network tools for recognizing relationships in systems with competing parameters, toward the goal of optimizing and accelerating the design of biomaterial scaffolds for articular cartilage tissue engineering. PMID: 19754250 [PubMed - as supplied by publisher] |
| VEGF inhibits BMP2 expression in Rat Mesenchymal Stem Cells.
September 17, 2009 at 7:49 am
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| | VEGF inhibits BMP2 expression in Rat Mesenchymal Stem Cells. Tissue Eng Part A. 2009 Sep 15; Authors: Schönmeyr BH, Soares M, Avraham T, Clavin NW, Gewalli F, Mehrara BJ Introduction: While several studies report that BMPs and VEGF can act synergistically to improve bone tissue engineering, others suggest that VEGF inhibits osteogenesis. The purpose of these experiments was therefore to evaluate the effect of dual transfection of these growth factors and potential mechanisms of interaction on gene expression and osteogenesis in vitro and in vivo. Methods: Marrow-derived mesenchymal stem cells (MSCs) were exposed to recombinant VEGF protein or transfected with adenoviruses encoding BMP2, VEGF, or LacZ in a variety of ratios. Alterations in gene and protein expression in vitro as well as bone formation in vivo were assessed. Results: MSC exposure to AdV-VEGF or recombinant VEGF inhibited BMP2 mRNA expression, protein production and MSC differentiation. Co-culture experiments revealed that BMP2 suppression occurs through both an autocrine and paracrine mechanism, occurring at the transcriptional level. Compared to controls, co-transfection of VEGF and BMP2 transgenes prevented ectopic bone formation in vivo. Conclusion: VEGF is a potent inhibitor of BMP2 expression in MSCs and supplementation or overexpression of VEGF inhibits osteogenesis in vitro and ectopic bone formation in vivo. Strategies to utilize MSCs in bone tissue engineering therefore require careful optimization and precise delivery of growth factors for maximal bone formation. PMID: 19754224 [PubMed - as supplied by publisher] |
| Characteristic change and loss of in vivo osteogenic abilities of human bone marrow stromal cells during passage.
September 17, 2009 at 7:49 am
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| | Characteristic change and loss of in vivo osteogenic abilities of human bone marrow stromal cells during passage. Tissue Eng Part A. 2009 Sep 15; Authors: Agata H, Asahina I, Watanabe N, Ishii Y, Kubo N, Ohshima S, Yamazaki M, Tojo A, Kagami H Although human bone marrow stromal cells (BMSCs) have the ability to form bone when transplanted, the responsible factors for in vivo osteogenic abilities are poorly understood. Here, we report conditions that are required for human BMSCs to demonstrate their in vivo osteogenic abilities. BMSCs were obtained from healthy donors and their in vivo osteogenic abilities were analyzed. Transplantation analyses revealed that passage number and length of osteogenic induction significantly affected ectopic bone formation. Although two weeks induction increased the percentage of success in bone formation compared to one week induction, BMSCs completely lost their in vivo osteogenic ability after passage 4 regardless of the length of osteogenic induction. Despite their in vivo osteogenic ability, no significant difference was observed in alkaline phosphatase activity or gene expression of osteogenic markers between BMSCs at passages 1 and 3. Differences were only observed in in vitro mineralizing abilities. Application of bFGF helped to maintain the BMSCs in vivo osteogenic ability, while bFGF altered cell growth and expression of HLA-DR. The results strongly suggest that there are several required conditions for human BMSCs to demonstrate their bone-forming capabilities, which should be further investigated and considered when designing a protocol for clinical bone tissue engineering. PMID: 19754223 [PubMed - as supplied by publisher] |
| PROTEOGLYCAN AND COLLAGEN ACCUMULATION BY PASSAGED CHONDROCYTES CAN BE ENHANCED THROUGH SIDE BY SIDE CULTURE WITH PRIMARY CHONDROCYTES.
September 17, 2009 at 7:49 am
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| | PROTEOGLYCAN AND COLLAGEN ACCUMULATION BY PASSAGED CHONDROCYTES CAN BE ENHANCED THROUGH SIDE BY SIDE CULTURE WITH PRIMARY CHONDROCYTES. Tissue Eng Part A. 2009 Sep 15; Authors: Taylor DW, Ahmed N, Gan L, Gross AE, Kandel R Identifying a source of sufficient numbers of chondrocytes for cartilage tissue engineering is a major factor limiting its use clinically. Previously we demonstrated that combined co-culture of passaged dedifferentiated articular chondrocytes with primary bovine chondrocytes will induce their redifferentiation. In this study we determine if these two cell types have to be in contact, whether human chondrocytes respond similarly, and if the ability of primary cells to influence passaged cells depends on the age of the donor. Co-culture of primary and passaged bovine chondrocytes grown on filter inserts placed in the same culture well but not in direct contact resulted in the passaged cells accumulating matrix rich in proteoglycans and type II collagen. There was upregulation of type II collagen and Sox9 and decrease in type I collagen gene expression in the passaged cells, to levels not significantly different than in primary chondrocytes. Passaged chondrocytes obtained from older animals responded similarly to cells from younger animals. As well, passaged human chondrocytes were also induced to form cartilage tissue when placed in side-by-side culture with bovine chondrocytes, this data suggests that a soluble factor(s) may be responsible for redifferentiation of passaged chondrocytes and that it is not species specific. The responsiveness of human chondrocytes to this factor(s) suggests that this approach may be suitable to overcome the problem of limited chondrocyte numbers for cartilage tissue engineering. PMID: 19754222 [PubMed - as supplied by publisher] |
| Synthesis and Characterization of Degradable Polar Hydrophobic Ionic Polyurethane Scaffolds for Vascular Tissue Engineering Applications.
September 17, 2009 at 7:49 am
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| | Synthesis and Characterization of Degradable Polar Hydrophobic Ionic Polyurethane Scaffolds for Vascular Tissue Engineering Applications. Biomacromolecules. 2009 Sep 15; Authors: Sharifpoor S, Labow RS, Santerre JP In tissue engineering, the ability to manipulate scaffold design characteristics is important to achieve functional tissue regeneration. In this study, degradable polar hydrophobic ionic polyurethane (D-PHI) porous scaffolds were synthesized using a lysine-based divinyl oligomer (DVO). Optimization studies on the DVO and D-PHI scaffold synthesis were conducted to maximize isocyanate and methacrylate monomer conversion, respectively. D-PHI scaffold properties were manipulated through the introduction of a lysine-based cross-linker. Specifically, increasing D-PHI cross-linker concentration resulted in an increase of the elastic modulus (0.5-21 MPa), a decrease of the elongation-at-yield (45-5%) and a reduction of scaffold swelling (170-100%). Based on a preliminary study with A10 vascular smooth muscle cells, D-PHI scaffolds demonstrated the ability to support cell adhesion and growth during 2 weeks of culture, suggesting their potential suitability for longer term vascular tissue engineering. The versatility of the D-PHI properties may allow for the tailoring of cell-material interaction and ultimately functional tissue regeneration. PMID: 19754121 [PubMed - as supplied by publisher] |
| Generation and transplantation of an autologous vascularized bioartificial human tissue.
September 17, 2009 at 7:49 am
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| | Generation and transplantation of an autologous vascularized bioartificial human tissue. Transplantation. 2009 Jul 27;88(2):203-10 Authors: Mertsching H, Schanz J, Steger V, Schandar M, Schenk M, Hansmann J, Dally I, Friedel G, Walles T BACKGROUND: The lack of transplant vascularization forecloses the generation and clinical implementation of bioartificial tissues. We developed techniques to generate a bioartificial human tissue with an innate vascularization. The tissue was implanted clinically as proof of concept to evaluate vascular network thrombogenicity and tissue viability after transplantation. METHODS: A porcine small bowl segment was decellularized in a two-step procedure, preserving its vascular structures. The extracellular matrix was characterized quantitatively for DNA residues and protein composition. The vascular remainings were reseeded with human endothelial cells in a dynamic tissue culture. The engineered tissue was characterized by (1) histology, (2) immune-histology, (3) life-dead assay, and (4) metabolic activity. To evaluate the tissue capabilities, it was implanted clinically and recovered after 1 week. RESULTS: Tissue preparation with sodium desoxycholate monohydrate solution resulted in an incomplete decellularization. Cell residues were removed by additional tissue incubation with DNAse. The human endothelial cells formed a viable endothelium inside the primarily porcine extracellular matrix, expressing CD31, Flk-1, and vascular endothelium-cadherin. The metabolic activity of the bioartificial tissue increased continuously over time in vitro. Clinical tissue transplantation confirmed vessel patency and tissue viability for 1 week. CONCLUSIONS: The feasibility to bioengineer a human tissue with an innate vascularization has been shown in vitro and the clinical setting. These results may open the door for the clinical application of various sophisticated bioartificial tissue substitutes and organ replacements. PMID: 19623015 [PubMed - indexed for MEDLINE] |
| Wnt7a activates the planar cell polarity pathway to drive the symmetric expansion of satellite stem cells.
September 17, 2009 at 7:49 am
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| | Wnt7a activates the planar cell polarity pathway to drive the symmetric expansion of satellite stem cells. Cell Stem Cell. 2009 Jun 5;4(6):535-47 Authors: Le Grand F, Jones AE, Seale V, Scimè A, Rudnicki MA Satellite cells in skeletal muscle are a heterogeneous population of stem cells and committed progenitors. We found that quiescent satellite stem cells expressed the Wnt receptor Fzd7 and that its candidate ligand Wnt7a was upregulated during regeneration. Wnt7a markedly stimulated the symmetric expansion of satellite stem cells but did not affect the growth or differentiation of myoblasts. Silencing of Fzd7 abrogated Wnt7a binding and stimulation of stem cell expansion. Wnt7a signaling induced the polarized distribution of the planar cell polarity effector Vangl2. Silencing of Vangl2 inhibited Wnt7a action on satellite stem cell expansion. Wnt7a overexpression enhanced muscle regeneration and increased both satellite cell numbers and the proportion of satellite stem cells. Muscle lacking Wnt7a exhibited a marked decrease in satellite cell number following regeneration. Therefore, Wnt7a signaling through the planar cell polarity pathway controls the homeostatic level of satellite stem cells and hence regulates the regenerative potential of muscle. PMID: 19497282 [PubMed - indexed for MEDLINE] |
| Origins.
September 17, 2009 at 7:49 am
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| | Origins. Tissue Eng Part A. 2009 Jul;15(7):1449-50 Authors: Lysaght MJ, Crager J PMID: 19327019 [PubMed - indexed for MEDLINE] |
| Long-term survival and integration of transplanted engineered nervous tissue constructs promotes peripheral nerve regeneration.
September 17, 2009 at 7:49 am
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| | Long-term survival and integration of transplanted engineered nervous tissue constructs promotes peripheral nerve regeneration. Tissue Eng Part A. 2009 Jul;15(7):1677-85 Authors: Huang JH, Cullen DK, Browne KD, Groff R, Zhang J, Pfister BJ, Zager EL, Smith DH Although peripheral nerve injury is a common consequence of trauma or surgery, there are insufficient means for repair. In particular, there is a critical need for improved methods to facilitate regeneration of axons across major nerve lesions. Here, we engineered transplantable living nervous tissue constructs to provide a labeled pathway to guide host axonal regeneration. These constructs consisted of stretch-grown, longitudinally aligned living axonal tracts inserted into poly(glycolic acid) tubes. The constructs (allogenic) were transplanted to bridge an excised segment of sciatic nerve in the rat, and histological analyses were performed at 6 and 16 weeks posttransplantation to determine graft survival, integration, and host regeneration. At both time points, the transplanted constructs were found to have maintained their pretransplant geometry, with surviving clusters of graft neuronal somata at the extremities of the constructs spanned by tracts of axons. Throughout the transplanted region, there was an intertwining plexus of host and graft axons, suggesting that the transplanted axons mediated host axonal regeneration across the lesion. By 16 weeks posttransplant, extensive myelination of axons was observed throughout the transplant region. Further, graft neurons had extended axons beyond the margins of the transplanted region, penetrating into the host nerve. Notably, this survival and integration of the allogenic constructs occurred in the absence of immunosuppression therapy. These findings demonstrate the promise of living tissue-engineered axonal constructs to bridge major nerve lesions and promote host regeneration, potentially by providing axon-mediated axonal outgrowth and guidance. PMID: 19231968 [PubMed - indexed for MEDLINE] |
| Synthesis of a tissue-engineered periosteum with acellular dermal matrix and cultured mesenchymal stem cells.
September 17, 2009 at 7:49 am
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| | Synthesis of a tissue-engineered periosteum with acellular dermal matrix and cultured mesenchymal stem cells. Tissue Eng Part A. 2009 Jul;15(7):1833-41 Authors: Schönmeyr B, Clavin N, Avraham T, Longo V, Mehrara BJ Periosteal grafts can aid in bone repair by providing bone progenitor cells and acting as a barrier to scar tissue. Unfortunately, these grafts have many of the same disadvantages as bone grafts (donor site morbidity and limited donor sites). In this article, we describe a method of synthesizing a periosteum-like material using acellular human dermis and osteoblasts or mesenchymal stem cells (MSC). We show that osteoblasts readily attach to and proliferate on the acellular human dermis in vitro. In addition, osteoblasts retained the potential for differentiation in response to bone morphogenetic protein stimulation. Cells grown on the acellular human dermis were efficiently transfected with adenoviruses with no evidence of cellular toxicity. To assess for in vivo cell delivery and bone-forming potential, the acellular human dermis was seeded with green fluorescent protein (GFP)-positive MSCs, transfected with bone morphogenetic protein 2, wrapped around the adductor muscle in syngeneic mice, and used to treat critical-sized mandibular defects in nude rats. After 3 weeks, GFP-positive cells were still present, and bone had replaced the interface between the muscle and the constructs. After 6 weeks, critical-sized bone defects had been successfully healed. In conclusion, we show that an acellular human dermis can be used to synthesize a tissue-engineered periosteum capable of delivering cells and osteoinductive proteins. PMID: 19125645 [PubMed - indexed for MEDLINE] |
| Macrophage participation in the degradation and remodeling of extracellular matrix scaffolds.
September 17, 2009 at 7:49 am
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| | Macrophage participation in the degradation and remodeling of extracellular matrix scaffolds. Tissue Eng Part A. 2009 Jul;15(7):1687-94 Authors: Valentin JE, Stewart-Akers AM, Gilbert TW, Badylak SF Biologic scaffolds composed of extracellular matrix (ECM) are widely used to facilitate remodeling and reconstruction of a variety of tissues in both preclinical animal studies and human clinical applications. The mechanisms by which such scaffolds influence the host tissue response are only partially understood, but it is logical that the mononuclear macrophage cell population plays a central role. The present study evaluated the role of macrophages that derive from peripheral blood in the degradation of ECM scaffolds. An established rat body wall reconstruction model was used to evaluate the degradation of carbodiimide (CDI)-crosslinked scaffolds composed of porcine small intestinal submucosa (SIS), noncrosslinked SIS, and autologous body wall. To assess the role of circulating macrophages in the degradation process, the degradation of each scaffold was assessed with and without macrophage depletion caused by administration of clodronate-containing liposomes. Results showed that peripheral blood monocytes are required for the early and rapid degradation of both SIS scaffolds and autologous body wall, and that CDI crosslinked SIS is resistant to macrophage-mediated degradation. PMID: 19125644 [PubMed - indexed for MEDLINE] |
| Enhanced tissue integration during cartilage repair in vitro can be achieved by inhibiting chondrocyte death at the wound edge.
September 17, 2009 at 7:49 am
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| | Enhanced tissue integration during cartilage repair in vitro can be achieved by inhibiting chondrocyte death at the wound edge. Tissue Eng Part A. 2009 Jul;15(7):1739-49 Authors: Gilbert SJ, Singhrao SK, Khan IM, Gonzalez LG, Thomson BM, Burdon D, Duance VC, Archer CW OBJECTIVE: Experimental wounding of articular cartilage results in cell death at the lesion edge. The objective of this study was to investigate whether inhibition of this cell death results in enhanced integrative cartilage repair. METHODS: Bovine articular cartilage discs (6 mm) were incubated in media containing inhibitors of necrosis (Necrostatin-1, Nec-1) or apoptosis (Z-VAD-FMK, ZVF) before cutting a 3 mm inner core. This core was left in situ to create disc/ring composites, cultured for up to 6 weeks with the inhibitors, and analyzed for cell death, sulfated glycosaminoglycan release, and tissue integration. RESULTS: Creating the disc/ring composites resulted in a significant increase in necrosis. ZVF significantly reduced necrosis and apoptosis at the wound edge. Nec-1 reduced necrosis. Both inhibitors reduced the level of wound-induced sulfated glycosaminoglycan loss. Toluidine blue staining and electron microscopy of cartilage revealed significant integration of the wound edges in disc/ring composites treated with ZVF. Nec-1 improved integration, but to a lesser extent. Push-out testing revealed that ZVF increased adhesive strength compared to control composites. CONCLUSIONS: This study shows that treatment of articular cartilage with cell death inhibitors during wound repair increases the number of viable cells at the wound edge, prevents matrix loss, and results in a significant improvement in cartilage-cartilage integration. PMID: 19119922 [PubMed - indexed for MEDLINE] |
| Tissue reactions to engineered cartilage based on poly-L-lactic acid scaffolds.
September 17, 2009 at 7:49 am
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| | Tissue reactions to engineered cartilage based on poly-L-lactic acid scaffolds. Tissue Eng Part A. 2009 Jul;15(7):1565-77 Authors: Fujihara Y, Asawa Y, Takato T, Hoshi K Tissue reactions against poly-L-lactic acid (PLLA) in engineered cartilage may influence the size or maturity of regenerative tissue. To understand the biological events in these reactions, we subcutaneously transplanted engineered constructs of PLLA scaffolds with or without human chondrocytes or atelocollagen in nude mice and evaluated neovascularization and macrophage activation, which can be assessed even in nude mice. Although not showing cartilage regeneration, PLLA alone demonstrated dense localization of macrophages and blood vessels, as well as a high level of interleukin-1 beta and tissue hemoglobin at 2 and 8 weeks. Otherwise, constructs with PLLA and chondrocytes with or without atelocollagen (PLLA/cell/gel or PLLA/cell) formed mature cartilage by 8 weeks, which was more prominent in PLLA/cell/gel. Although accumulation of macrophages and blood vessels in PLLA/cell/gel and PLLA/cell was comparable with that in PLLA at 2 weeks, that in PLLA/cell/gel markedly decreased by 8 weeks, with blood vessels and macrophages excluded into non-cartilage areas. Macrophage migration inhibitory factor could be involved in these suppressed tissue reactions, because it was expressed in chondrocytes of engineered cartilage. Intense tissue reactions inevitably occurred in biopolymers alone, but it is possible that maturation of engineered cartilage suppressed these reactions, which may contribute to circumventing deformity or malformation of engineered tissues. PMID: 19115823 [PubMed - indexed for MEDLINE] |
| In vivo comparison of biomimetic approaches for tissue regeneration of the scarred vocal fold.
September 17, 2009 at 7:49 am
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| | In vivo comparison of biomimetic approaches for tissue regeneration of the scarred vocal fold. Tissue Eng Part A. 2009 Jul;15(7):1481-7 Authors: Thibeault SL, Klemuk SA, Smith ME, Leugers C, Prestwich G The objective of this study was to determine if three different biomimetic approaches could facilitate tissue regeneration and improve viscoelastic properties in the scarred vocal fold lamina propria extracellular matrix (ECM). Twenty rabbit vocal folds were biopsied bilaterally; 2 months postinjury rabbits were unilaterally treated with (i) autologous fibroblasts, (ii) a semisynthetic ECM (sECM), or (iii) autologous fibroblasts encapsulated in sECM. Saline was injected as a control into the contralateral fold. Animals were sacrificed 2 months after treatment. Outcomes measured were procollagen, collagen, and fibronectin levels in the lamina propria, and tissue viscosity and elasticity across three frequency decades. All treatment groups demonstrated accelerated proliferation of the ECM. Vocal fold lamina propria treated with autologous fibroblasts were found to have significantly improved viscosity (p = 0.0077) and elasticity (p = 0.0081) compared to saline. This treatment group had significantly elevated fibronectin levels. sECM and autologous fibroblasts/sECM groups had significantly elevated levels of procollagen, collagen, and fibronectin, indicating abundant matrix production as compared to saline with viscoelastic measures that did not differ statistically from controls. The use of autologous fibroblasts led to better restoration of the vocal fold lamina propria biomechanical properties. Optimization of cell-scaffold interactions and subsequent cell behavior is necessary for utilization of scaffold and scaffold-cell approaches. PMID: 19072088 [PubMed - indexed for MEDLINE] |
| Reconstruction of engineered uterine tissues containing smooth muscle layer in collagen/matrigel scaffold in vitro.
September 17, 2009 at 7:49 am
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| | Reconstruction of engineered uterine tissues containing smooth muscle layer in collagen/matrigel scaffold in vitro. Tissue Eng Part A. 2009 Jul;15(7):1611-8 Authors: Lü SH, Wang HB, Liu H, Wang HP, Lin QX, Li DX, Song YX, Duan CM, Feng LX, Wang CY OBJECTIVE: This study attempted to reconstruct engineered uterine tissues (EUTs) containing smooth muscle layer, akin to the normal uterine wall. METHODS: EUTs were reconstructed by seeding epithelial cells on top of the constructed stromal layer over smooth muscle layer. A self-made mold was used to keep the EUTs from contraction. At the same time, it provided static stretch to the EUTs. After 14 days of culture, the structure of the EUTs was analyzed histologically and immunohistochemically, or by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The expression of integrin beta3 subunit, heparin-binding epidermal growth factor (EGF)-like growth factor (HB-EGF), and HOXA-10 was detected by reverse transcription-polymerase chain reaction (RT-PCR). The ability of the EUTs supporting the development of embryos was estimated by coculturing embryos on the EUTs. We also tried a new method to reconstruct EUTs by mixing epithelial cell and stromal cells (1:2) in collagen/Matrigel to form an endometrial layer and putting it on top of the smooth muscle layer. The self-assembling ability of the endometrial epithelial cells and stromal cells in the reconstructed EUTs was analyzed histologically and immunohistochemically. RESULTS: The results found that the constructed EUTs with the first and the second method showed three-layered structures. The epithelial layer, stromal layer, and smooth muscle layer were stained by cytokeratin 18, vimentin, and alpha-actin, respectively. TEM showed that the cells in the EUTs reconstructed by the first method were attached to each other by apical tight junctions and rivet-like desmosomes. SEM showed protruded pinopodes, microvilli, and cilium of epithelial cells. The RT-PCR analysis showed that integrin beta3 subunit, HB-EGF, and HOXA-10 were expressed in EUTs. The coculture system of EUTs improved the development rate and quality of murine embryo significantly in comparison with those of control Chatot Ziomek Bavister culture. In the EUTs reconstructed by the second method, the epithelial cells demonstrated self-assembling ability and formed epithelial cell layer on top of the stromal layer and glandular tube-like structures in the stromal layer. Columnar epithelial cells existed in some parts of the epithelial layer. CONCLUSION: We engineered EUTs containing smooth muscle layer by two methods. The reconstructed EUTs could support the development of embryos. The epithelial cells showed self-assembling ability in the EUTs. PMID: 19061433 [PubMed - indexed for MEDLINE] |
| Chitosan nano-/microfibrous double-layered membrane with rolled-up three-dimensional structures for chondrocyte cultivation.
September 17, 2009 at 7:49 am
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| | Chitosan nano-/microfibrous double-layered membrane with rolled-up three-dimensional structures for chondrocyte cultivation. J Biomed Mater Res A. 2009 Aug;90(2):595-602 Authors: Shim IK, Suh WH, Lee SY, Lee SH, Heo SJ, Lee MC, Lee SJ With an aim to mimic natural extracellular matrix, we fabricated the nano- and microfibrous matrix with chitosan by electrospinning nanofibers onto predefined microfibrous mesh for effective chondrocytes cultivation. Rolling the double-layered nano-/microfibrous membranes produced three-dimensional (3-D) scaffolds that exhibited the interconnected open pore structure in their scanning electron microscopy images. In vitro chondrocyte culture experiment showed that this nano-/microfibrous 3-D matrix provided a significantly greater microenvironment for chondrocytes to proliferate and produce glycosaminoglycan as compared with only microfibrous 3-D matrix. This difference could be explained by the result on 2-D membrane, where chitosan nanofibrous surface substantially facilitated the cellular attachment and proliferation, and efficiently prevented phenotypic changes of chondrocytes, when compared with chitosan microfibrous membrane and film. In this regard, the nano-/microfibrous 3-D matrix we fabricated in this study would possess a great potential as a system for effective chondrocyte cultivation and also for application to cartilage regeneration therapy. PMID: 18563820 [PubMed - indexed for MEDLINE] |
| Bone growth is enhanced by novel bioceramic coatings on Ti alloy implants.
September 17, 2009 at 7:49 am
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| | Bone growth is enhanced by novel bioceramic coatings on Ti alloy implants. J Biomed Mater Res A. 2009 Aug;90(2):419-28 Authors: Wang C, Karlis GA, Anderson GI, Dunstan CR, Carbone A, Berger G, Ploska U, Zreiqat H Calcium phosphate ceramics are widely used as coating materials to orthopedic implants and are found to enhance initial bony ingrowth by stimulating osseous apposition to the implant surface. In this study, two novel calcium orthophosphate materials were selected for coating onto the commonly used orthopedic implant material Ti-6Al- 4V. One was calcium alkali orthophosphate with the crystalline phase Ca10[K/Na](PO4)7 with a small addition of SiO2 (AW-Si) and the other was calcium orthophosphate composed of 70 mol % fluorapatite, Ca10(PO4)6F2 and 30 mol % CaZr4(PO4)6 (FA7Z). The coated implants were placed in cortical and cortico-cancellous bone of sheep femur for six weeks. Retrieved samples were tested for osseointegration and mechanical strength. It was found that both coatings produced enhanced bone/implant contact rate compared to the control when implanted in cortico-cancellous bone. This study demonstrates that the two coatings have the capability of encouraging bone growth, and hence the potential for being used as coating materials on Ti implants. PMID: 18523954 [PubMed - indexed for MEDLINE] |
| Effect of seeding technique and scaffold material on bone formation in tissue-engineered constructs.
September 17, 2009 at 7:49 am
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| | Effect of seeding technique and scaffold material on bone formation in tissue-engineered constructs. J Biomed Mater Res A. 2009 Aug;90(2):429-37 Authors: Schliephake H, Zghoul N, Jäger V, van Griensven M, Zeichen J, Gelinsky M, Wülfing T The aim of the present study was to test the hypothesis that both scaffold material and the type of cell culturing contribute to the results of in vivo osteogenesis in tissue-engineered constructs in an interactive manner. CaCO3 scaffolds and mineralized collagen scaffolds were seeded with human trabecular bone cells at a density of 5 x 10(6) cells/cm(3) and were left to attach under standard conditions for 24 h. Subsequently, they were submitted to static and dynamic culturing for 14 days (groups III and IV, respectively). Dynamic culturing was carried out in a continuous flow perfusion bioreactor. Empty scaffolds and scaffolds that were seeded with cells and kept under standard conditions for 24 h served as controls (groups I and II, respectively). Five scaffolds of each biomaterial and from each group were implanted into the gluteal muscles of rnu rats for 6 weeks. Osteogenesis was assessed quantitatively by histomorphometry and expression of osteocalcin (OC) and vascular endothelial growth factor (VEGF) was determined by immunohistochemistry. CaCO3 scaffolds exhibited 15.8% (SD 3.1) of newly formed bone after static culture and 22.4% (SD 8.2) after dynamic culture. Empty control scaffolds did not show bone formation, and scaffolds after 24 h of standard conditions produced 8.2% of newly formed bone (SD 4.0). Differences between the controls and the scaffolds cultured for 14 days were significant, but there was no significant difference between static and dynamic culturing. Mineralized collagen scaffolds did not show bone formation in any group. There was a significant difference in the expression of OC within the scaffolds submitted to static versus dynamic culturing in the CaCO3 scaffolds. VEGF expression did not show significant differences between static and dynamic culturing in the two biomaterials tested. It is concluded that within the limitations of the study the type of biomaterial had the dominant effect on in vivo bone formation in small tissue-engineered scaffolds. The culture period additionally affected the amount of bone formed, whereas the type of culturing may have had a positive effect on the expression of osteogenic markers but not on the quantity of bone formation. PMID: 18523951 [PubMed - indexed for MEDLINE] | | | 
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