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| Engineering Musculoskeletal Tissues with Human Embryonic Germ Cell Derivatives.
February 24, 2010 at 6:23 AM
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| | Engineering Musculoskeletal Tissues with Human Embryonic Germ Cell Derivatives. Stem Cells. 2010 Feb 22; Authors: Varghese S, Hwang N, Ferran A, Hillel A, Theprungsirikul P, Canver AC, Zhang Z, Gearhart J, Elisseeff J The cells derived from differentiating embryoid bodies of human embryonic germ (hEG) cells express a broad spectrum of gene markers and have been induced towards ecto- and endodermal lineages. We describe here in vitro and in vivo differentiation of hEG-derived cells (LVEC line) towards mesenchymal tissues. The LVEC cells express many surface marker proteins characteristic of mesenchymal stem cells and differentiated into cartilage, bone, and fat. Homogenous hyaline cartilage was generated from cells after 63 population-doublings. In vivo results demonstrate cell survival, differentiation, and tissue formation. The high proliferative capacity of hEG-derived cells and their ability to differentiate and form 3D mesenchymal tissues without teratoma formation underscores their significant potential for regenerative medicine. The adopted coculture system also provides new insights into how a microenvironment comprising of extracellular and cellular components may be ha! rnessed to generate hierarchically complex tissues from pluripotent cells. PMID: 20178108 [PubMed - as supplied by publisher] | | |
| Derivation of the King's College London human embryonic stem cell lines.
February 24, 2010 at 6:23 AM
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| | Derivation of the King's College London human embryonic stem cell lines. In Vitro Cell Dev Biol Anim. 2010 Feb 23; Authors: Stephenson EL, Braude PR Since the derivation of the first human embryonic stem cell (hESC) line in 1998, there has been substantial interest in the potential of these cells for regenerative medicine and cell therapy and in the use of hESCs carrying clinically relevant genetic mutations as models for disease research and therapeutic target identification. There is still a need to improve derivation efficiency and further the understanding of the basic biology of these cells and to develop clinical grade culture systems with the aim of producing cell lines suitable for subsequent manipulation for therapy. The derivation of initial hESC lines at King's College London is discussed here, with focus on derivation methodology. Each of the derivations was distinctive. Although the stage and morphology of each blastocyst were generally similar in each attempt, the behaviour of the colonies was unpredictable; colony morphology and development was different with each attempt. Days 5, 6 and 7 blasto! cysts were used successfully, and the number of days until appearance of stem-like cells varied from 4 to 14 d. Routine characterisation analyses were performed on three lines, all of which displayed appropriate marker expression and survived cryopreservation-thaw cycles. From the lines discussed, four are at various stages of the deposition process with the UKSCB, one is pending submission and two are unsuitable for banking. Continued open and transparent reporting of results and collaborations will maximise the efficiency of derivation and facilitate the development of standardised protocols for the derivation and early culture of hESC lines. PMID: 20178004 [PubMed - as supplied by publisher] | | |
| Derivation of a new human embryonic stem cell line, Endeavour-2, and its characterization.
February 24, 2010 at 6:23 AM
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| | Derivation of a new human embryonic stem cell line, Endeavour-2, and its characterization. In Vitro Cell Dev Biol Anim. 2010 Feb 23; Authors: Sidhu KS, Ryan JP, Lees JG, Tuch BE Here, we describe the derivation of a novel human embryonic stem cell (hESC) line, Endeavour-2 (E-2), propagated on human fetal fibroblasts (HFF) in a serum-replacement media. The inner cell mass (ICM) was manually dissected from the blastocyst without using immunodissection and, therefore, antibodies from animal sources. A total of 20 embryos were thawed and cultured, eight embryos were hatched, and five ICMs were obtained. They were transferred onto HFF used as feeder layer, and one colony representing the initial cell proliferation of a new hESC line, E-2, was obtained. The newly emerged hESC colony was passaged first by physical dissection and subsequently by enzymatic dissociation. E-2 has been in culture for over 6 months and has been shown to possess typical features of a pluripotent hESC line including expression of stem cell surface markers (SSEA4, TRA-160, and integrin alpha-6), intracellular alkaline phosphatase, and pluripotency gene markers, OCT4 and ! NANOG. This hESC line shows lineage-specific differentiation into various representative cell types expressing markers characteristic of the three somatic germ layers under both in vitro and in vivo conditions. E-2 line shows a normal karyotype (46 XX) and has been successfully cryopreserved and thawed several times using slow-freezing procedures. E-2 adds to the repertoire of existing hESC lines for research and development purposes in the field of regenerative medicine. PMID: 20178001 [PubMed - as supplied by publisher] | | |
| Derivation and characterization of three new human embryonic stem cell lines in Finland.
February 24, 2010 at 6:23 AM
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| | Derivation and characterization of three new human embryonic stem cell lines in Finland. In Vitro Cell Dev Biol Anim. 2010 Feb 23; Authors: Skottman H Human embryonic stem cell (hESC) lines can be established from the preimplantation embryos. Due to their ability to differentiate into all three embryonic layers, hESC are of significant interest as a renewable source of cell material for different applications, especially for cell replacement therapy. Since the establishment of the first hESC lines in 1998, several studies have described the derivation and culture of new hESC lines using various derivation methods and culture conditions. Our group has currently established eight new hESC lines of which three of the latest ones are described in a more detailed way in this report. The described lines have been established using mechanical derivation methods for surplus bad quality embryos and culture conditions containing human foreskin fibroblast feeder cells and serum-free culture medium. All the new lines have a normal karyotype and typical hESC characteristics analyzed in vitro. The described hESC lines are ava! ilable for research purposes upon request ( www.regea.fi ). PMID: 20177999 [PubMed - as supplied by publisher] | | |
| Derivation of human embryonic stem cells at the Center of Regenerative Medicine in Barcelona.
February 24, 2010 at 6:23 AM
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| | Derivation of human embryonic stem cells at the Center of Regenerative Medicine in Barcelona. In Vitro Cell Dev Biol Anim. 2010 Feb 23; Authors: Aran B, Rodríguez-Pizà I, Raya A, Consiglio A, Muñoz Y, Barri PN, Izpisúa JC, Veiga A We report here the legislative issues related to embryo research and human embryonic stem cell (hESC) research in Spain and the derivation of nine hESC lines at the Center of Regenerative Medicine in Barcelona. You can find the information for obtaining our lines for research purposes at blc@cmrb.eu . PMID: 20177997 [PubMed - as supplied by publisher] | | |
| Characterization and differentiation potential of rat ventral mesencephalic neuronal progenitor cells immortalized with SV40 large T antigen.
February 24, 2010 at 6:23 AM
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| | Characterization and differentiation potential of rat ventral mesencephalic neuronal progenitor cells immortalized with SV40 large T antigen. Cell Tissue Res. 2010 Feb 23; Authors: Nobre A, Kalve I, Cesnulevicius K, Rangancokova D, Ratzka A, Halfer N, Wesemann M, Krampfl K, Claus P, Grothe C Neuronal progenitor cells (NPCs) possess high potential for use in regenerative medicine. To overcome their limited mitotic competence, various immortalization strategies have been applied that allow their prolonged maintenance and expansion in vitro. Such immortalized cells can be used for the design and discovery of new cell-based therapies for neurodegenerative diseases, such as Parkinson's disease. We immortalized rat ventral mesencephalic NPCs by using SV40 large T antigen (SV40Tag). All cell clones displayed a two- to three-fold higher proliferation rate compared with the primary cells. In order to induce dopaminergic differentiation of generated cell clones, both glial-derived neurotrophic factor and di-butyryl cyclic adenosine monophosphate were applied. Treated cells were then characterized regarding the expression of dopaminergic lineage markers, differentiation of various cell populations, calcium imaging in the presence of kainate, and immunohistochemi! stry after intrastriatal transplantation. Treated cells displayed morphological maturation, and calcium imaging revealed neuronal properties in the presence of kainate. These cells also expressed low mRNA levels of the dopamine transporter and tyrosine hydroxylase (TH), although no TH-immunopositive neurons were found. Intrastriatal transplantation into the neurotoxin-lesioned rats did not induce further differentiation. As an alternative approach, we silenced SV40Tag with short interfering RNA, but this was not sufficient to trigger differentiation into dopaminergic neurons. Nevertheless, neuronal and glial cells were detected as shown by beta-tubulin type III and glial fibrillary acidic protein staining, respectively. SV40Tag cells are suitable for carrying out controlled genetic modifications as shown by overexpression of enhanced green fluorescence protein after efficient non-viral transfection. PMID: 20177706 [PubMed - as supplied by publisher] | | |
| Alginate-encapsulated human hepatoma C3A cells for use in a bioartificial liver device - the hybrid-MDS.
February 24, 2010 at 6:23 AM
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| | Alginate-encapsulated human hepatoma C3A cells for use in a bioartificial liver device - the hybrid-MDS. Int J Artif Organs. 2009 Nov;32(11):769-78 Authors: Harm S, Stroble K, Hartmann J, Falkenhagen D PURPOSE: The aim of this study was to encapsulate C3A cells into alginate microcapsules with an average diameter of < or =100 microm, thus enabling them to be recirculated in a bioartificial liver device based on MDS (Microsphere-based Detoxification System) technology. The microcapsules have to be permeable for essential proteins such as albumin. METHODS: C3A cells were encapsulated using alginate. The resulting alginate beads were coated with poly(diallyldimethylammoniumchloride) (pDADMAC) and poly(sodium-p-styrenesulfonate) (pSS). Their mechanical stability was tested by recirculation of the microcapsule suspension, while their permeability was determined by reverse-size exclusion chromatography and by the use of a confocal laser microscope. The metabolic activities of encapsulated C3A cells were compared to freely growing adherent C3A cells in static cultivation models. The metabolic functionality of encapsulated C3A cells in static conditions was compared ! to encapsulated C3A cells in a dynamic model. RESULTS: The mean diameter of the resulting microcapsules was 86 mum. Our experiments show that these microcapsules were permeable for albumin and the high flow rate of 600 ml/min in a dynamic model has no influence on the survival and the metabolic activities of the encapsulated cells during the tested time of 24 hours. CONCLUSIONS: Alginate microcapsules containing C3A cells can be used to produce albumin and growth factors in a bioartificial or hybrid liver support system. Thanks to their small diameter, the microcapsules in suspension can be recirculated in the MDS. PMID: 20020408 [PubMed - indexed for MEDLINE] | | |
| Tissue engineering toward organ replacement: a promising approach in airway transplant.
February 24, 2010 at 6:23 AM
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| | Tissue engineering toward organ replacement: a promising approach in airway transplant. Int J Artif Organs. 2009 Nov;32(11):763-8 Authors: Asnaghi A, Macchiarini P, Mantero S Autologous tissue transfer, allografts and prosthetic replacements have so far failed to offer functional solutions for the treatment of long circumferential tracheal defects. Because of the shortcomings related with these strategies, interest has turned increasingly to the field of tissue engineering which applies the principles of engineering and life sciences in an effort to develop in vitro biological substitutes able to restore, maintain, or improve tissue and organ function. The advances in this field during the past decade have thus provided a new attractive approach toward the concept of functional substitutes and may represent an alternative to the shortage of suitable grafts for reconstructive airway surgery. This article gives an overview of the tissue engineering approach and of the encouraging strategies attempted so far in trachea regeneration. PMID: 20020407 [PubMed - indexed for MEDLINE] | | |
| Innovation in basic science: stem cells and their role in the treatment of paediatric cardiac failure--opportunities and challenges.
February 24, 2010 at 6:23 AM
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| | Innovation in basic science: stem cells and their role in the treatment of paediatric cardiac failure--opportunities and challenges. Cardiol Young. 2009 Nov;19 Suppl 2:74-84 Authors: Kaushal S, Jacobs JP, Gossett JG, Steele A, Steele P, Davis CR, Pahl E, Vijayan K, Asante-Korang A, Boucek RJ, Backer CL, Wold LE Heart failure is a leading cause of death worldwide. Current therapies only delay progression of the cardiac disease or replace the diseased heart with cardiac transplantation. Stem cells represent a recently discovered novel approach to the treatment of cardiac failure that may facilitate the replacement of diseased cardiac tissue and subsequently lead to improved cardiac function and cardiac regeneration. A stem cell is defined as a cell with the properties of being clonogenic, self-renewing, and multipotent. In response to intercellular signalling or environmental stimuli, stem cells differentiate into cells derived from any of the three primary germ layers: ectoderm, endoderm, and mesoderm, a powerful advantage for regenerative therapies. Meanwhile, a cardiac progenitor cell is a multipotent cell that can differentiate into cells of any of the cardiac lineages, including endothelial cells and cardiomyocytes. Stem cells can be classified into three categories: ! (1) adult stem cells, (2) embryonic stem cells, and (3) induced pluripotential cells. Adult stem cells have been identified in numerous organs and tissues in adults, including bone-marrow, skeletal muscle, adipose tissue, and, as was recently discovered, the heart. Embryonic stem cells are derived from the inner cell mass of the blastocyst stage of the developing embryo. Finally through transcriptional reprogramming, somatic cells, such as fibroblasts, can be converted into induced pluripotential cells that resemble embryonic stem cells. Four classes of stem cells that may lead to cardiac regeneration are: (1) Embryonic stem cells, (2) Bone Marrow derived stem cells, (3) Skeletal myoblasts, and (4) Cardiac stem cells and cardiac progenitor cells. Embryonic stem cells are problematic because of several reasons: (1) the formation of teratomas, (2) potential immunologic cellular rejection, (3) low efficiency of their differentiation into cardiomyocytes, typically 1% in culture! , and (4) ethical and political issues. As of now, bone marrow! derived stem cells have not been proven to differentiate reproducibly and reliably into cardiomyocytes. Skeletal myoblasts have created in vivo myotubes but have not electrically integrated with the myocardium. Cardiac stem cells and cardiac progenitor cells represent one of the most promising types of cellular therapy for children with cardiac failure. PMID: 19857353 [PubMed - indexed for MEDLINE] | | |
| Gellan gum injectable hydrogels for cartilage tissue engineering applications: in vitro studies and preliminary in vivo evaluation.
February 24, 2010 at 6:23 AM
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| | Gellan gum injectable hydrogels for cartilage tissue engineering applications: in vitro studies and preliminary in vivo evaluation. Tissue Eng Part A. 2010 Jan;16(1):343-53 Authors: Oliveira JT, Santos TC, Martins L, Picciochi R, Marques AP, Castro AG, Neves NM, Mano JF, Reis RL Gellan gum is a polysaccharide that we have previously proposed for applications in the cartilage tissue engineering field. In this work, gellan gum hydrogels were tested for their ability to be used as injectable systems using simple processing methods, able to deliver and maintain chondrocytes by in situ gelation, and support cell viability and production of extracellular matrix (ECM). Rheological measurements determined that the sol-gel transition occurred near the body temperature at 39 degrees C, upon temperature decrease, in approximately 20 s. Gellan gum discs shows a storage compression modulus of around 80 kPa at a frequency of 1 Hz by dynamic mechanical analysis. Human articular chondrocytes were encapsulated in the gels, cultured in vitro for total periods of 56 days, and analyzed for cell viability and ECM production. Calcein AM staining showed that cell kept viable after 14 days and the histological analysis and real-time quantitative polymerase chain! reaction revealed that hyaline-like cartilage ECM was synthesized. Finally, the in vivo performance of the gellan gum hydrogels, in terms of induced inflammatory reaction and integration into the host tissue, was evaluated by subcutaneous implantation in Balb/c mice for 21 days. Histological analysis showed a residual fibrotic capsule at the end of the experiments. Dynamic mechanical analysis revealed that the gels were stable throughout the experiments while evidencing a tendency for decreasing mechanical properties, which was consistent with weight measurements. Altogether, the results demonstrate the adequacy of gellan gum hydrogels processed by simple methods for noninvasive injectable applications toward the formation of a functional cartilage tissue-engineered construct and originally report the preliminary response of a living organism to the subcutaneous implantation of the gellan gum hydrogels. These are the two novel features of this work. PMID: 19702512 [PubMed - indexed for MEDLINE] | | |
| Development and characterization of a novel hybrid tissue engineering-based scaffold for spinal cord injury repair.
February 24, 2010 at 6:23 AM
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| | Development and characterization of a novel hybrid tissue engineering-based scaffold for spinal cord injury repair. Tissue Eng Part A. 2010 Jan;16(1):45-54 Authors: Silva NA, Salgado AJ, Sousa RA, Oliveira JT, Pedro AJ, Leite-Almeida H, Cerqueira R, Almeida A, Mastronardi F, Mano JF, Neves NM, Sousa N, Reis RL Spinal cord injury (SCI) represents a significant health and social problem, and therefore it is vital to develop novel strategies that can specifically target it. In this context, the objective of the present work was to develop a new range of three-dimensional (3D) tubular structures aimed at inducing the regeneration within SCI sites. Up to six different 3D tubular structures were initially developed by rapid prototyping: 3D bioplotting-based on a biodegradable blend of starch. These structures were then further complemented by injecting Gellan Gum, a polysaccharide-based hydrogel, in the central area of structures. The mechanical properties of these structures were assessed using dynamic mechanical analysis, under both dry and wet conditions, and their morphologies/porosities were analyzed using micro-computed tomography and scanning electron microscopy. Biological evaluation was carried out to determine their cytotoxicity, using both minimum essential medium ! (MEM) extraction and MTS tests, as well as by encapsulation of an oligodendrocyte-like cell (M03-13 cell line) within the hydrogel phase. The histomorphometric analysis showed a fully interconnected network of pores with porosity ranging from 70% to 85%. Scaffolds presented compressive modulus ranging from 17.4 to 62.0 MPa and 4.42 to 27.4 MPa under dry and wet conditions, respectively. Cytotoxicity assays revealed that the hybrid starch/poly-epsilon-caprolactone/Gellan Gum scaffolds were noncytotoxic, as they did not cause major alterations on cell morphology, proliferation, and metabolic viability. Moreover, preliminary cell encapsulation assays showed that the hybrid scaffolds could support the in vitro culture of oligodendrocyte-like cells. Finally, preliminary in vivo studies conducted in a hemisection rat SCI model revealed that the above-referred structures were well integrated within the injury and did not trigger chronic inflammatory processes. The results herein p! resented indicate that these 3D systems might be of use in fut! ure SCI regeneration approaches. PMID: 19614546 [PubMed - indexed for MEDLINE] | | |
| In vivo cyclic loading as a potent stimulatory signal for bone formation inside tissue engineering scaffold.
February 24, 2010 at 6:18 AM
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| | In vivo cyclic loading as a potent stimulatory signal for bone formation inside tissue engineering scaffold. Eur Cell Mater. 2010;19:41-9 Authors: Roshan-Ghias A, Terrier A, Bourban PE, Pioletti DP In clinical situations, bone defects are often located at load bearing sites. Tissue engineering scaffolds are future bone substitutes and hence they will be subjected to mechanical stimulation. The goal of this study was to test if cyclic loading can be used as stimulatory signal for bone formation in a bone scaffold. Poly(L-lactic acid) (PLA)/ 5% beta-tricalcium phosphate (beta-TCP) scaffolds were implanted in both distal femoral epiphyses of eight rats. Right knees were stimulated (10N, 4Hz, 5 min) five times, every two days, starting from the third day after surgery while left knees served as control. Finite element study of the in vivo model showed that the strain applied to the scaffold is similar to physiological strains. Using micro-computed tomography (CT), all knees were scanned five times after the surgery and the related bone parameters of the newly formed bone were quantified. Statistical modeling was used to estimate the evolution of these parameters! as a function of time and loading. The results showed that mechanical stimulation had two effects on bone volume (BV): an initial decrease in BV at week 2, and a long-term increase in the rate of bone formation by 28%. At week 13, the BV was then significantly higher in the loaded scaffolds. PMID: 20178097 [PubMed - in process] | | |
| Histone Deacetylase Inhibitors Attenuate Acute Lung Injury During Cecal Ligation and Puncture-Induced Polymicrobial Sepsis.
February 24, 2010 at 6:18 AM
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| | Histone Deacetylase Inhibitors Attenuate Acute Lung Injury During Cecal Ligation and Puncture-Induced Polymicrobial Sepsis. World J Surg. 2010 Feb 23; Authors: Zhang L, Jin S, Wang C, Jiang R, Wan J BACKGROUND: The histone deacetylase (HDAC) inhibitors have emerged as the useful reagents that epigenetically modulate the expression of various genes. In the present study, the effects of HDAC inhibitors on the expression of inflammation-related genes and lung injury during sepsis were investigated. METHODS: Mice were pretreated with two structurally unrelated HDAC inhibitors, Trichostatin A (TSA) and sodium butyrate (SB). Thirty minutes later, mice underwent cecal ligation and puncture (CLP)-induced sepsis. Lung injury and the expression of inflammation-related molecules were determined. In addition, survival was assessed post-CLP. RESULTS: Our results indicated that administration of TSA or SB alleviated sepsis-induced lung injury. This was accompanied by reduced neutrophil infiltration, decreased intercellular adhesion molecule-1 (ICAM-1) and E-selectin expression in lung tissue, and lower interleukin-6 (IL-6) level in plasma. In addition, treatment with HDAC ! inhibitors significantly prolonged the survival time of CLP mice. CONCLUSIONS: These data indicated that the HDAC inhibitors, based on modulating the key enzymes linked to acetylation modification, effectively attenuate intrapulmonary inflammatory response, thus significantly alleviating lung injury during sepsis. PMID: 20177680 [PubMed - as supplied by publisher] | | |
| Follistatin-like-1, a diffusible mesenchymal factor determines the fate of epithelium.
February 24, 2010 at 6:18 AM
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| | Follistatin-like-1, a diffusible mesenchymal factor determines the fate of epithelium. Proc Natl Acad Sci U S A. 2010 Feb 22; Authors: Umezu T, Yamanouchi H, Iida Y, Miura M, Tomooka Y Mesenchyme is generally believed to play critical roles in "secondary induction" during organogenesis. Because of the complexity of tissue interactions in secondary inductions, however, little is known about the precise mechanisms at the cellular and molecular levels. We have demonstrated that, in mouse oviductal development, the mesenchyme determines the fate of undetermined epithelial cells to become secretory or cilial cells. We have established a model for studying secondary induction by establishing clonal epithelial and mesenchymal cell lines from perinatal p53(-/-) mouse oviducts. The signal sequence trap method collected candidate molecules secreted from mesenchymal cell lines. Naive epithelial cells exposed to Follistatin-like-1 (Fstl1), one of the candidates, became irreversibly committed to expressing a cilial epithelial marker and differentiated into ciliated cells. We concluded that Fstl1 is one of the mesenchymal factors determining oviductal epithel! ial cell fate. This is a unique demonstration that the determination of epithelial cell fate is induced by a single diffusible factor. PMID: 20176958 [PubMed - as supplied by publisher] | | |
| The effect of BMP-2 on micro and macroscale osteointegration of biphasic calcium phosphate scaffolds with multiscale porosity.
February 24, 2010 at 6:18 AM
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| | The effect of BMP-2 on micro and macroscale osteointegration of biphasic calcium phosphate scaffolds with multiscale porosity. Acta Biomater. 2010 Feb 19; Authors: Lan Levengood SK, Polak SJ, Poellmann MJ, Hoelzle DJ, Maki AJ, Clark SG, Wheeler MB, Wagoner Johnson AJ It is well established that scaffolds for applications in bone tissue engineering require interconnected pores on the order of 100um for bone growth, and nutrient and waste transport. As a result, most studies of have focused on macroporosity (>100um). More recently, researchers have also investigated the role of microporosity in calcium phosphaste (CaP) based scaffolds. Osteointegration into macropores improves when scaffold rods or struts contain micropores, typically defined as pores less than approximately 50um. We recently demonstrated multiscale osteointegration, or growth into both macropores and micropores (<10um), of rods in biphasic CaP (BCP) scaffolds. The combined effect of BMP-2, a potent osteoinductive growth factor, and multiscale porosity has yet to be investigated. In this study, we implanted BCP scaffolds into porcine mandibles for 3, 6, 12, and 24 weeks and evaluated the effect of BMP-2 on multiscale osteointegration. Results showed, for t! his in vivo model, that BMP-2 influences osteointegration at the microscale, but not at the macroscale. Cell density was higher in the rod micropores for scaffolds containing BMP-2 compared to controls at all time points, but BMP-2 was not required for bone formation in micropores. In contrast, there was essentially no difference in fraction of bone in macropores for scaffolds with BMP-2 compared to controls. Additionally, bone in macropores seemed to have reached steady state by 3 weeks. Multiscale osteointegration results in composites that are fully osteointegrated, with no "dead space," and are likely to have not only a continuous cell network, but also the potential for enhanced load transfer and improved mechanical properties. PMID: 20176148 [PubMed - as supplied by publisher] | | |
| Fibroblasts facilitate the engraftment of embryonic stem cell-derived cardiomyocytes on three-dimensional collagen matrices and aggregation in hanging drops.
February 24, 2010 at 6:18 AM
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| | Fibroblasts facilitate the engraftment of embryonic stem cell-derived cardiomyocytes on three-dimensional collagen matrices and aggregation in hanging drops. Stem Cells Dev. 2010 Feb 22; Authors: Pfannkuche K, Neuss S, Pillekamp F, Frenzel L, Attia W, Hannes T, Salber J, Hoss M, Zenke M, Fleischmann B, Hescheler J, Saric T There is growing interest in use of cardiomyocytes purified from embryonic stem (ES) cells for tissue engineering and cardiomyoplasty. However, most of transplanted cells are lost shortly after transplantation due to the lack of integration into the host tissue and subsequent apoptosis. Here we examine whether murine embryonic fibroblasts (MEFs) can support the integration of purified murine ES cell-derived cardiomyocytes in a three-dimensional tissue culture model based on a freezed-dryed collagen matrix with tubular structure. Collagen matrix was seeded either with cardiomyocytes alone or in combination with MEFs. The collagen sponges that were transplanted with cardiomyocytes alone did neither show morphological nor functional integration of viable cells. Cardiomyocytes also did not appear to be capable of attaching quantitatively to any of 16 different two-dimensional biomaterials. However, cardiomyocytes co-cultured with MEFs formed fibre-like structures of r! od-shaped cells with organized sarcomeric structure that contracted spontaneously. Electrical coupling between cardiomyocytes was suggested by strong expression of connexin 43. In addition, MEFs as well as cardiac fibroblasts supported re-aggregation of dissociated cardiomyocytes in hanging drops in the absence of collagen matrix. We conclude that fibroblasts promote cardiomyocyte engraftment and formation of functional three-dimensional tissue in vitro. Elucidation of the mechanism of this phenomenon may help improving the integration of cardiomyocytes in vivo. PMID: 20175666 [PubMed - as supplied by publisher] | | |
| Invited commentary.
February 24, 2010 at 6:18 AM
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| | Invited commentary. J Vasc Surg. 2010 Jan;51(1):183 Authors: Golden MA PMID: 20117501 [PubMed - indexed for MEDLINE] | | |
| The fate of an endothelium layer after preconditioning.
February 24, 2010 at 6:18 AM
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| | The fate of an endothelium layer after preconditioning. J Vasc Surg. 2010 Jan;51(1):174-83 Authors: Yazdani SK, Tillman BW, Berry JL, Soker S, Geary RL BACKGROUND: A strategy in minimizing thrombotic events of vascular constructs is to seed the luminal surface with autologous endothelial cells (ECs). The task of seeding ECs can be achieved via bioreactors, which induce mechanical forces (shear stress, strain, pressure) onto the ECs. Although bioreactors can achieve a confluent layer of ECs in vitro, their acute response to blood remains unclear. Moreover, the necessary mechanical conditions that will increase EC adhesion and function remain unclear. We hypothesize that preconditioning seeded endothelium under physiological flow will enhance their retention and function. OBJECTIVE: To determine the role of varying preconditioning protocols on seeded ECs in vitro and in vivo. METHODS: Scaffolds derived from decelluarized arteries seeded with autologous ECs were preconditioned for 9 days. Three specific protocols, low steady shear stress (SS), high SS, and cyclic SS were investigated. After preconditioning, the seed! ed grafts were exposed to 15 minutes of blood via an ex vivo arteriovenous shunt model or alternately an in vivo arteriovenous bypass graft model. RESULTS: The shunt model demonstrated ECs remained intact for all conditions. In the arteriovenous bypass model, only the cyclic preconditioned grafts remained intact, maintained morphology, and resisted the attachment of circulating blood elements such as platelets, red blood cells, and leukocytes. Western blotting analysis demonstrated an increase in the protein expression of eNOS and prostaglandin I synthase for the cyclic high shear stress-conditioned cells relative to cells conditioned with high shear stress alone. CONCLUSION: Cyclic preconditioning has been shown here to increase the ECs ability to resist blood flow-induced shear stress and the attachment of circulating blood elements, key attributes in minimizing thrombotic events. These studies may ultimately establish protocols for the formation of a more durable endothe! lial monolayer that may be useful in the context of small vess! el arter ial reconstruction. PMID: 20117500 [PubMed - indexed for MEDLINE] | | |
| CIRM Directors to Take Position on Affordability, Accountability Measure
February 24, 2010 at 2:39 AM
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| Directors of the California stem cell agency on March 4 will take their first public look at new legislation aimed at ensuring affordable access to therapies financed by taxpayers, including proposals to improve accountability and openness at the state research effort.
Also on the table at the meeting of the directors' Legislative Subcommittee is legislation to create a state board to deal with | | | | 
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