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| IOM Study of California Stem Cell Agency Proposed
May 19, 2010 at 7:04 PM
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| A directors subcommittee of the California stem cell agency next week will consider commissioning a blue-ribbon, outside study of its work, ranging from its organizational structure to its scientific performance.
The study would be conducted by the prestigious Institute of Medicine and be paid for by CIRM. The proposal comes as legislation is being considered in Sacramento that would require | | |
| CIRM Legislation Noted on HealthyCal
May 19, 2010 at 12:14 PM
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| Legislation to remove the 50-person cap on the number of employees at the California stem cell agency drew a smidgen of notice on HealthyCal.org, a relatively new Web site that deals extensively with health policy issues.
Dan Weintraub, former columnist for The Sacramento Bee, posted a brief item linking to our piece last week on the measure. Among other things, he said,
"A lot of people have | | |
| Stem cell tracking by nanotechnologies.
May 19, 2010 at 8:32 AM
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| | Stem cell tracking by nanotechnologies. Int J Mol Sci. 2010;11(3):1070-81 Authors: Villa C, Erratico S, Razini P, Fiori F, Rustichelli F, Torrente Y, Belicchi M Advances in stem cell research have provided important understanding of the cell biology and offered great promise for developing new strategies for tissue regeneration. The beneficial effects of stem cell therapy depend also by the development of new approachs for the track of stem cells in living subjects over time after transplantation. Recent developments in the use of nanotechnologies have contributed to advance of the high-resolution in vivo imaging methods, including positron emission tomography (PET), single-photon emission tomography (SPECT), magnetic resonance (MR) imaging, and X-Ray computed microtomography (microCT). This review examines the use of nanotechnologies for stem cell tracking. PMID: 20480000 [PubMed - in process] | | |
| Therapeutic Applications of Mesenchymal Stem Cells to Repair Kidney Injury.
May 19, 2010 at 8:32 AM
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| | Therapeutic Applications of Mesenchymal Stem Cells to Repair Kidney Injury. J Urol. 2010 May 15; Authors: Asanuma H, Meldrum DR, Meldrum KK PURPOSE: The potential use of stem cells for acute and chronic renal injury is under intensive investigation. We summarized the current literature on the potential therapeutic role of mesenchymal stem cells for kidney injury. MATERIALS AND METHODS: We reviewed the pertinent literature on mesenchymal stem cell therapy for acute and chronic renal injury. RESULTS: Experimental evidence suggests that administering exogenous mesenchymal stem cells during acute and chronic kidney injury may improve functional and structural recovery of the tubular, glomerular and interstitial kidney compartments. Several studies point to a paracrine and/or endocrine mechanism of action rather than to direct repopulation of cells in the injured nephron. Multiple questions remain unanswered regarding the protective action of mesenchymal stem cells during renal injury, including signals that regulate stem cell homing to injured tissue, factors regulating paracrine and/or endocrine activity! of exogenous mesenchymal stem cells and particularly the long-term behavior of administered stem cells in vivo. CONCLUSIONS: Many questions remain unanswered but mesenchymal stem cell based therapy is a promising new strategy for acute and chronic kidney disease. PMID: 20478602 [PubMed - as supplied by publisher] | | |
| Intracardiac injection of matrigel induces stem cell recruitment and improves cardiac functions in a rat myocardial infarction model.
May 19, 2010 at 8:32 AM
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| | Intracardiac injection of matrigel induces stem cell recruitment and improves cardiac functions in a rat myocardial infarction model. J Cell Mol Med. 2010 May 14; Authors: Ou L, Li W, Zhang Y, Wang W, Liu J, Sorg H, Furlani D, Gäbel R, Mark P, Klopsch C, Wang L, Lützow K, Lendlein A, Wagner K, Klee D, Liebold A, Li RK, Kong D, Steinhoff G, Ma N Abstract Background: Matrigel promotes angiogenesis in the myocardium from ischemic injury and prevents remodeling of the myocardium. We assessed the therapeutic efficacy of intracardiac Matrigel injection and matrigel-mediated stem cell homing in a rat myocardial infarction (MI) model. Methods and Results: Following MI, Matrigel (250mul) or PBS was delivered by intracardiac injection. Compared to myocardial infarction control group (MI-PBS), Matrigel significantly improved left ventricular function (n=11, P<0.05) assessed by pressure-volume loops after 4 weeks. There is no significant difference in infarct size between MI-M (21.48+/-1.49%, n=10) and MI-PBS hearts (20.98+/-1.25%, n=10). The infarct wall thickness of left ventricular (LWT) is significantly higher (P<0.01) in MI-M (0.72+/-0.02mm, n=10) compared with MI-PBS (0.62+/-0.02mm, n=10). MI-Matrigel (MI-M) hearts exhibited higher capillary density (border 130.8+/-4.7 vs.115.4 +/- 6.0, P<0.05; vessel! s per HPF (400x), n=6) than MI-PBS hearts. c-Kit(+) stem cells (38.3+/-5.3 vs. 25.7+/-1.5 c-Kit(+) cells per HPF(630x), n=5, P<0.05) and CD34(+) cells (13.0+/-1.51 vs. 5.6+/-0.68 CD34(+) cells per HPF (630x), n=5, P<0.01) were significantly more numerous in MI-Matrigel than in MI-PBS in the infarcted hearts (n=5, P<0.05). Conclusions: Intracardiac Matrigel injection restores myocardial functions following MI, which may attribute to the improved recruitment of CD34(+) and c-Kit(+) stem cells. PMID: 20477905 [PubMed - as supplied by publisher] | | |
| Advances in surgical approaches to Crohn's disease: minimally invasive surgery and biologic therapy.
May 19, 2010 at 8:32 AM
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| | Advances in surgical approaches to Crohn's disease: minimally invasive surgery and biologic therapy. Expert Rev Clin Immunol. 2009 Jul;5(4):463-70 Authors: Holubar SD, Wolff BG In the last 5 years, significant advances have been made in the surgical approaches to, and medical management of, Crohn's disease (CD). This review summarizes these advances as they relate to the care of surgical patients with CD, with an emphasis on innovations in surgical techniques, specifically minimally invasive (laparoscopic) surgery, as well as on recent developments in biologic pharmacotherapies for CD that have important clinical implications for surgical patients. These include recent insights gained into the role of biologic therapy with infliximab and other newer agents in preoperative and postoperative therapy of CD patients. We will also review other recent developments relevant to the current and future surgical care of CD patients, including the treatment of less common forms of CD, such as duodenal and colonic CD, and the role of novel strategies such as fibrin glue, fistula plugs and stem cell therapy for the treatment of fistulizing anorectal C! D. PMID: 20477042 [PubMed - in process] | | |
| Technological Aspects of Regenerative Medicine and Tissue Engineering of Articular Cartilage.
May 19, 2010 at 6:59 AM
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| | Technological Aspects of Regenerative Medicine and Tissue Engineering of Articular Cartilage. Handchir Mikrochir Plast Chir. 2010 May 17; Authors: Pörtner R, Meenen NM The main problem in the treatment of orthopaedic joint-surface defects will be solved by tissue enginering of cartilage implants. Entire biological osteochondral implants can be grown from autologous cells of the patient. The nutrition of articular cartilage is by diffusion only. Therefore the chondrocyte as the unique cell type is perfectly dedicated to the tissue culture approach. Engineering techniques of bioreactors are prerequisite for these biological and medical solutions. With our tissue engineering project for the generation of osteochondral constructs we demonstrate possibilities and characteristics of bioreactors for the modification of cell culture techniques and mechanical conditioning of cartilage tissue for fully operable implants. PMID: 20480456 [PubMed - as supplied by publisher] | | |
| Neurobiology of injury to the developing brain.
May 19, 2010 at 6:59 AM
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| | Neurobiology of injury to the developing brain. Nat Rev Neurol. 2010 May 18; Authors: Deng W Owing to improved survival rates of premature newborns, the number of very low birth weight infants is rising. Preterm infants display a greater propensity for brain injury caused by hypoxic or ischemic events, infection and/or inflammation that results in prominent white matter injury (WMI) than infants carried to full term. The intrinsic vulnerability of developing oligodendroglia to excitotoxic, oxidative and inflammatory forms of injury is a major factor in the pathogenesis of this condition. Furthermore, activated microglia and astrogliosis are critically involved in triggering WMI. Currently, no specific treatment is available for this kind of injury. Injury to the premature brain can substantially influence brain development and lead to disability. Impairment of the main motor pathways, such as the corticospinal tract, in the perinatal period contributes substantially to clinical outcome. Advanced neuroimaging techniques have led to greater understanding of! the nature of both white and gray matter injury in preterm infants. Further research is warranted to examine the translational potential of preclinical therapeutic strategies for controlling such injury and preserving the integrity of motor pathways in preterm infants. PMID: 20479779 [PubMed - as supplied by publisher] | | |
| Activation of dormant ovarian follicles to generate mature eggs.
May 19, 2010 at 6:59 AM
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| | Activation of dormant ovarian follicles to generate mature eggs. Proc Natl Acad Sci U S A. 2010 May 17; Authors: Li J, Kawamura K, Cheng Y, Liu S, Klein C, Liu S, Duan EK, Hsueh AJ Although multiple follicles are present in mammalian ovaries, most of them remain dormant for years or decades. During reproductive life, some follicles are activated for development. Genetically modified mouse models with oocyte-specific deletion of genes in the PTEN-PI3K-Akt-Foxo3 pathway exhibited premature activation of all dormant follicles. Using an inhibitor of the Phosphatase with TENsin homology deleted in chromosome 10 (PTEN) phosphatase and a PI3K activating peptide, we found that short-term treatment of neonatal mouse ovaries increased nuclear exclusion of Foxo3 in primordial oocytes. After transplantation under kidney capsules of ovariectomized hosts, treated follicles developed to the preovulatory stage with mature eggs displaying normal epigenetic changes of imprinted genes. After in vitro fertilization and embryo transfer, healthy progeny with proven fertility were delivered. Human ovarian cortical fragments from cancer patients were also treated w! ith the PTEN inhibitor. After xeno-transplantation to immune-deficient mice for 6 months, primordial follicles developed to the preovulatory stage with oocytes capable of undergoing nuclear maturation. Major differences between male and female mammals are unlimited number of sperm and paucity of mature oocytes. Thus, short-term in vitro activation of dormant ovarian follicles after stimulation of the PI3K-Akt pathway allows the generation of a large supply of mature female germ cells for future treatment of infertile women with a diminishing ovarian reserve and for cancer patients with cryo-preserved ovaries. Generation of a large number of human oocytes also facilitates future derivation of embryonic stem cells for regenerative medicine. PMID: 20479243 [PubMed - as supplied by publisher] | | |
| Smad7 regulates the adult neural stem/progenitor cell pool in a TGF-{beta} and BMP-independent manner.
May 19, 2010 at 6:59 AM
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| | Smad7 regulates the adult neural stem/progenitor cell pool in a TGF-{beta} and BMP-independent manner. Mol Cell Biol. 2010 May 17; Authors: Krampert M, Chirasani SR, Wachs FP, Aigner R, Bogdahn U, Yingling JM, Heldin CH, Aigner L, Heuchel R Members of the transforming growth factor (TGF)-beta family of proteins modulate the proliferation, differentiation and survival of many different cell types. Neural stem and progenitor cells (NPCs) in the adult brain are inhibited in their proliferation by TGF-beta and by bone morphogenetic proteins (BMPs). Here, we investigated neurogenesis in a hypomorphic mouse model for the TGF-beta and BMP inhibitor Smad7, with the hypothesis that NPC proliferation might be reduced due to increased TGF-beta and BMP signaling. Unexpectedly, we found enhanced NPC proliferation as well as an increased number of label-retaining cells in vivo. The enhanced proliferation potential of mutant cells was retained in vitro in neurosphere cultures. We observed both a higher sphere-forming capacity as well as faster growth and cell cycle progression. Use of specific inhibitors revealed that these effects were independent of TGF-beta and BMP signaling. The enhanced proliferation might be ! at least partially mediated by elevated signaling via epidermal growth factor (EGF) receptor, as mutant cells showed higher expression and activation levels of the EGF-receptor. Conversely, an EGF receptor inhibitor reduced the proliferation of these cells. Our data indicate that endogenous Smad7 regulates neural stem/progenitor cell proliferation in a TGF-beta and BMP-independent manner. PMID: 20479122 [PubMed - as supplied by publisher] | | |
| A role for the Werner syndrome protein in epigenetic inactivation of the pluripotency factor Oct4.
May 19, 2010 at 6:59 AM
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| | A role for the Werner syndrome protein in epigenetic inactivation of the pluripotency factor Oct4. Aging Cell. 2010 May 10; Authors: Smith JA, Ndoye AM, Geary K, Lisanti MP, Igoucheva O, Daniel R Summary Werner syndrome (WS) is an autosomal recessive disorder, the hallmarks of which are premature aging and early onset of neoplastic diseases (Orren 2006; Bohr 2008). The gene, whose mutation underlies the WS phenotype, is called WRN. The protein encoded by the WRN gene, WRNp, has DNA helicase activity (Gray et al. 1997; Orren 2006; Bohr 2008; Opresko 2008). Extensive evidence suggests that WRNp plays a role in DNA replication and DNA repair (Chen et al. 2003; Hickson 2003; Orren 2006; Turaga et al. 2007; Bohr 2008). However, WRNp function is not yet fully understood. In this study, we show that WRNp is involved in de novo DNA methylation of the promoter of the Oct4 gene, which encodes a crucial stem cell transcription factor. We demonstrate that WRNp localizes to the Oct4 promoter during retinoic acid-induced differentiation of human pluripotent cells, and associates with the de novo methyltransferase Dnmt3b in the chromatin of differentiating pluripotent ce! lls. Depletion of WRNp does not affect demethylation of lysine 4 of the histone H3 at the Oct4 promoter, nor methylation of lysine 9 of H3, but it blocks recruitment of Dnmt3b to the promoter and results in reduced methylation of CpG sites within the Oct4 promoter. The lack of DNA methylation was associated with continued, albeit greatly reduced, Oct4 expression in WRN-deficient, retinoic acid-treated cells, which resulted in attenuated differentiation. The presented results reveal a novel function of WRNp, and demonstrate that WRNp controls a key step in pluripotent stem cell differentiation. PMID: 20477760 [PubMed - as supplied by publisher] | | |
| Novel gene therapeutic strategies for the induction of tolerance in cornea transplantation.
May 19, 2010 at 6:59 AM
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| | Novel gene therapeutic strategies for the induction of tolerance in cornea transplantation. Expert Rev Clin Immunol. 2009 Nov;5(6):749-64 Authors: Ritter T, Pleyer U With more than 100,000 procedures each year, corneal transplantation (keratoplasty) is the most frequent transplantation procedure in humans. Technical advances in microsurgery have moved forward to transplant isolated layers of the cornea; however, immune-mediated allograft rejection is still a key problem and continued therapeutic efforts are required to improve the prognosis of keratoplasty. New treatment protocols need to be introduced to prevent the rejection of allogeneic grafts. The genetic modification of the graft or cells prior to transplantation is an attractive approach to protect the graft from allogeneic rejection. The transplant setting offers the unique advantage for gene therapy to modify allografts ex vivo prior to transplantation. In this review, novel therapeutic strategies using recombinant viruses as gene-transfer vehicles and, more recently, the use of gene-modified dendritic cells or regulatory T cells to protect the graft from immune-media! ted rejection will be discussed. PMID: 20477694 [PubMed - in process] | | |
| Skin Tissue Engineering - from Split Skin to Engineered Skin Grafts?
May 19, 2010 at 6:26 AM
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| | Skin Tissue Engineering - from Split Skin to Engineered Skin Grafts? Handchir Mikrochir Plast Chir. 2010 May 17; Authors: Beier JP, Boos AM, Kamolz L, Vogt PM, Koller R, Horch RE Today split or full skin grafts are still the gold standard in the treatment of substance defects of the skin. Such results can be seen, for example, in the therapy for burn patients. However, in patients with more than 50% burned skin area, donor sites are limited. Likewise in chronic wound patients inferior take rates of skin grafts as compared to burn wounds are observed. This may be attributed, for example, to accompanying or underlying chronic diseases or a higher rate of local infections. These phenomena also lead to a lack of availability of transplantable skin grafts. Hence the need for cost effective and user friendly synthetic or engineered skin grafts, which can serve for acute and chronic wounds and which can be also used in critically ill patients, is at hand. During the last 30 years a huge number of biological and synthetic skin graft materials and products based on the patient's own cells were launched on the market. Researchers and clinicians are ! constantly working on further improvements. One possibility is the engineering of skin grafts in vitro, which have to be integrated into the wound bed after transplantation. Another approach is the fabrication of biocompatible and bioresorbable matrices, which can attract host cells and stimulate a wound-healing process without scars. However, the skin graft materials available today cannot yet replace split or full skin grafts completely because of their inherent limitations such as insufficient take rates and/or the lack of mechanical stability and differentiated structures of the grafted artificial skin. Thus researchers in the field of skin tissue engineering are still working on the final goal of developing a skin graft which has all the features of healthy human skin and is capable of replacing human skin completely. This article gives on overview of the currently available solutions and products in the field of skin tissue engineering. PMID: 20480457 [PubMed - as supplied by publisher] | | |
| Technological Aspects of Regenerative Medicine and Tissue Engineering of Articular Cartilage.
May 19, 2010 at 6:26 AM
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| | Technological Aspects of Regenerative Medicine and Tissue Engineering of Articular Cartilage. Handchir Mikrochir Plast Chir. 2010 May 17; Authors: Pörtner R, Meenen NM The main problem in the treatment of orthopaedic joint-surface defects will be solved by tissue enginering of cartilage implants. Entire biological osteochondral implants can be grown from autologous cells of the patient. The nutrition of articular cartilage is by diffusion only. Therefore the chondrocyte as the unique cell type is perfectly dedicated to the tissue culture approach. Engineering techniques of bioreactors are prerequisite for these biological and medical solutions. With our tissue engineering project for the generation of osteochondral constructs we demonstrate possibilities and characteristics of bioreactors for the modification of cell culture techniques and mechanical conditioning of cartilage tissue for fully operable implants. PMID: 20480456 [PubMed - as supplied by publisher] | | |
| Spatially controlled cell adhesion on three-dimensional substrates.
May 19, 2010 at 6:26 AM
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| | Spatially controlled cell adhesion on three-dimensional substrates. Biomed Microdevices. 2010 May 18; Authors: Richter C, Reinhardt M, Giselbrecht S, Leisen D, Trouillet V, Truckenmüller R, Blau A, Ziegler C, Welle A The microenvironment of cells in vivo is defined by spatiotemporal patterns of chemical and biophysical cues. Therefore, one important goal of tissue engineering is the generation of scaffolds with defined biofunctionalization in order to control processes like cell adhesion and differentiation. Mimicking extrinsic factors like integrin ligands presented by the extracellular matrix is one of the key elements to study cellular adhesion on biocompatible scaffolds. By using special thermoformable polymer films with anchored biomolecules micro structured scaffolds, e.g. curved and micro-patterned substrates, can be fabricated. Here, we present a novel strategy for the fabrication of micro-patterned scaffolds based on the "Substrate Modification and Replication by Thermoforming" (SMART) technology: The surface of a poly lactic acid membrane, having a low forming temperature of 60 degrees C and being initially very cell attractive, was coated with a photopatterned layer! of poly(L-lysine) (PLL) and hyaluronic acid (VAHyal) to gain spatial control over cell adhesion. Subsequently, this modified polymer membrane was thermoformed to create an array of spherical microcavities with diameters of 300 microm for 3D cell culture. Human hepatoma cells (HepG2) and mouse fibroblasts (L929) were used to demonstrate guided cell adhesion. HepG2 cells adhered and aggregated exclusively within these cavities without attaching to the passivated surfaces between the cavities. Also L929 cells adhering very strongly on the pristine substrate polymer were effectively patterned by the cell repellent properties of the hyaluronic acid based hydrogel. This is the first time cell adhesion was controlled by patterned functionalization of a polymeric substrate with UV curable PLL-VAHyal in thermoformed 3D microstructures. PMID: 20480241 [PubMed - as supplied by publisher] | | |
| Synthesis of a novel biodegradable polyurethane with phosphatidylcholines.
May 19, 2010 at 6:26 AM
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| | Synthesis of a novel biodegradable polyurethane with phosphatidylcholines. Int J Mol Sci. 2010;11(4):1870-7 Authors: Cao J, Chen N, Chen Y, Luo X A novel polyurethane was successfully synthesized by chain-extension of biodegradable poly (l-lactide) functionalized phosphatidylcholine (PC) with hexamethylene diisocyanate (HDI) as chain extender (PUR-PC). The molecular weights, glass transition temperature (Tg) increased significantly after the chain-extension. The hydrophilicity of PUR-PC was better than the one without PC, according to a water absorption test. Moreover, the number of adhesive platelets and anamorphic platelets on PUR-PC film were both less than those on PUR film. These preliminary results suggest that this novel polyurethane might be a better scaffold than traditional biodegradable polyurethanes for tissue engineering due to its better blood compatibility. Besides, this study also provides a new method to prepare PC-modified biodegradable polyurethanes. PMID: 20480047 [PubMed - in process] | | |
| High-throughput three-dimensional lithographic microfabrication.
May 19, 2010 at 6:26 AM
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| | High-throughput three-dimensional lithographic microfabrication. Opt Lett. 2010 May 15;35(10):1602-4 Authors: Kim D, So PT A 3D lithographic microfabrication process has been developed that is high throughput, scalable, and capable of producing arbitrary patterns. It offers the possibility for industrial scale manufacturing of 3D microdevices such as photonic crystals, tissue engineering scaffolds, and microfluidics chips. This method is based on depth-resolved wide-field illumination by temporally focusing femtosecond light pulses. We characterized the axial resolution of this technique, and the result is consistent with the theoretical prediction. As proof-of-concept experiments, we demonstrated photobleaching of 3D resolved patterns in a fluorescent medium and fabricating 3D microstructures with SU-8 photoresist. PMID: 20479822 [PubMed - in process] | | |
| A review on stereolithography and its applications in biomedical engineering.
May 19, 2010 at 6:26 AM
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| | A review on stereolithography and its applications in biomedical engineering. Biomaterials. 2010 May 15; Authors: Melchels FP, Feijen J, Grijpma DW Stereolithography is a solid freeform technique (SFF) that was introduced in the late 1980s. Although many other techniques have been developed since then, stereolithography remains one of the most powerful and versatile of all SFF techniques. It has the highest fabrication accuracy and an increasing number of materials that can be processed is becoming available. In this paper we discuss the characteristic features of the stereolithography technique and compare it to other SFF techniques. The biomedical applications of stereolithography are reviewed, as well as the biodegradable resin materials that have been developed for use with stereolithography. Finally, an overview of the application of stereolithography in preparing porous structures for tissue engineering is given. PMID: 20478613 [PubMed - as supplied by publisher] | | |
| Strain transfer in the annulus fibrosus under applied flexion.
May 19, 2010 at 6:26 AM
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| | Strain transfer in the annulus fibrosus under applied flexion. J Biomech. 2010 May 15; Authors: Desrochers J, Duncan NA A detailed understanding of the anatomical and mechanical environment in the intervertebral disc at the scale of the cell is necessary for the design of tissue engineering repair strategies and to elucidate the role of mechanical factors in pathology. The objective of this study was to measure and compare the macroscale to microscale strains in the outer annulus fibrosus in various cellular regions of intact discs over a range of applied flexion. Macroscale strains were measured on the annulus fibrosus surface, and contrasted to in situ microscale strains using novel confocal microscopy techniques for dual labeling of the cell and the extracellular matrix. Fiber oriented surface strains were significantly higher than in situ fiber strains, which implies a mechanism of load redistribution that minimizes strain along the fibers. Non-uniformity of the strains and matrix distortion occurred immediately and most interestingly varied little with increase in flexion (3-1! 6 degrees ), suggesting that inter-fiber shear is important in the initial stages of strain redistribution. Fiber oriented intercellular strains were significantly larger and compressive compared to in situ strains in other regions of the extracellular matrix indicating that the mechanical environment in this region may be unique. Further examination of the structural morphology in this pericellular region is needed to fully understand the pathway of strain transfer from the tissue to the cell. This study provides new knowledge on the complex in situ micro-mechanical environment of the annulus fibrosus that is essential to understanding the mechanobiological behavior of this tissue. PMID: 20478561 [PubMed - as supplied by publisher] | | |
| Three dimensional chitin-based scaffolds from Verongida sponges (Demospongiae: Porifera). Part II. Biomimetic potential and applications.
May 19, 2010 at 6:26 AM
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| | Three dimensional chitin-based scaffolds from Verongida sponges (Demospongiae: Porifera). Part II. Biomimetic potential and applications. Int J Biol Macromol. 2010 May 14; Authors: Ehrlich H, Steck E, Ilan M, Maldonado M, Muricy G, Bavestrello G, Kljajic Z, Carballo JL, Shiaparelli S, Ereskovsky A, Schupp P, Born R, Worch H, Bazhenov VV, Kurek D, Varlamow V, Vyalikh D, Kummer K, Sivkov VV, Molodtsov SL, Meissner H, Richter G, Hunoldt S, Kammer M, Paasch S, Krasokhin V, Patzke G, Brunner E, Richter W In order to evaluate the biomedical potential of three dimensional chitinous scaffolds of poriferan origin, chondrocyte culturing experiments were performed. It was shown for the first time that freshly isolated chondrocytes attached well to the chitin scaffold and synthesized an extracellular matrix similar to that found in other cartilage tissue engineering constructs. Chitin scaffolds also supported deposition of a proteoglycan-rich extracellular matrix of chondrocytes seeded bioconstructs in an in vivo environment. We suggest that chitin sponge scaffolds, apart from the demonstrated biomedical applications, are highly optimized structures for use as filtering systems, templates for biomineralization as well as metallization in order to produce catalysts. PMID: 20478334 [PubMed - as supplied by publisher] | | |
| Developing biodegradable scaffolds for tissue engineering of the urethra.
May 19, 2010 at 6:26 AM
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| | Developing biodegradable scaffolds for tissue engineering of the urethra. BJU Int. 2010 May 12; Authors: Selim M, Bullock AJ, Blackwood KA, Chapple CR, Macneil S OBJECTIVES To develop a synthetic biodegradable alternative to using human allodermis for the production of tissue-engineered buccal mucosa for substitution urethroplasty, looking specifically at issues of sterilization and cell-seeding protocols and, comparing the results to native buccal mucosa. MATERIAL AND METHODS Three methods of sterilization, peracetic acid (PAA), gamma-irradiation and ethanol, were evaluated for their effects on a biodegradable electrospun scaffold of polylactide-co-glycolide (PLGA, 85 : 15), to identify a sterilization method with minimal adverse effects on the scaffolds. Two protocols for seeding oral cells on the scaffold were compared, co-culture of fibroblasts and keratinocytes on the scaffolds for 14 days, and seeding fibroblasts for 5 days then adding keratinocytes for a further 10 days. Cell viability and proliferation on the scaffolds, scaffold contraction and mechanical properties of the scaffolds with and without cells were exam! ined. RESULTS gamma-irradiation and PAA sterilized scaffolds remained sterile for >3 months when incubated in antibiotic-free culture medium, while ethanol sterilized and unsterilized samples became infected within 2-14 days. All scaffolds showed extensive contraction (up to 50% over 14 days) irrespective of the method of sterilization or the presence of cells. All methods of sterilization, particularly ethanol, reduced the tensile strength of the scaffolds. The addition of cells tended to further reduce mechanical properties but increased elasticity. The cell-seeding protocol of adding fibroblasts for 5 days followed by keratinocytes for 10 days was the most promising, achieving a mean (sem) ultimate tensile stress of 1.20 (0.24) x 10(5) N/m(2) compared to 3.77 (1.05) x 10(5) N/m(2) for native buccal mucosa, and a Young's modulus of 2.40 (0.25) MPa, compared to 0.73 (0.09) MPa for the native buccal mucosa. CONCLUSION This study adds to our understanding of how steri! lization and cell seeding affect the physical properties of sc! affolds. Both PAA and gamma-irradiation appear to be suitable methods for sterilizing PLGA scaffolds, although both reduce the tensile properties of the scaffolds. Cells grow well on the sterilized scaffolds, and with our current protocol produce constructs which have approximately 30% of the mechanical strength and elasticity of the native buccal mucosa. We conclude that sterilized PLGA 85 : 15 is a promising material for producing tissue-engineered buccal mucosa. PMID: 20477828 [PubMed - as supplied by publisher] | | |
| [Implication of hyaluronic acid in normal and pathological angiogenesis. Application for cellular engineering]
May 19, 2010 at 6:26 AM
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| | [Implication of hyaluronic acid in normal and pathological angiogenesis. Application for cellular engineering] Ann Dermatol Venereol. 2010 Apr;137 Suppl 1:S15-22 Authors: Lataillade JJ, Albanese P, Uzan G Angiogenesis is a physiological process that allows the formation of new blood vessels, either from the local vascular structures, or from circulating endothelial progenitor cells, mobilized from the bone marrow, and attracted to the neovascularization site. This mechanism is controlled by pro-angiogenic molecules. It is crucial to supply oxygen and nutrients to tissues during growth, embryonic development or tissue regeneration in response to injuries. Thus, the dermis part of the skin is highly vascularized by a dense network of small and medium arteries and of capillaries and venules. In case of injury, rapid tissue repair is possible through this vascular network. However, once the vascularization is restored in tissue repair, the process of angiogenesis is negatively regulated by anti-angiogenic molecules. Controling the balance between pro-and anti-angiogenic agents is crucial and its deregulation leads to serious disease. The extracellular matrix plays an i! mportant role in controlling angiogenesis, allowing at least, the distribution of growth factors and the regulation of endothelial cell migration. Among these matrix components, hyaluronic acid plays a major role in the mechanical properties of connective tissues in ensuring their hydration. This glycosaminoglycan is a large size polymer, whose breakdown products strongly act on angiogenesis, especially in pathological situations (cancer, inflammation). Regarding its biological and mechanical properties, hyaluronic acid is used as matrix in tissue engineering, for improving the revascularization of tissues like skin. PMID: 20435250 [PubMed - in process] | | |
| Growth and differentiation potentials in confluent state of culture of human skeletal muscle myoblasts.
May 19, 2010 at 6:26 AM
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| | Growth and differentiation potentials in confluent state of culture of human skeletal muscle myoblasts. J Biosci Bioeng. 2010 Mar;109(3):310-3 Authors: Chowdhury SR, Muneyuki Y, Takezawa Y, Kino-oka M, Saito A, Sawa Y, Taya M The transitional behaviors of myoblasts toward differentiation were investigated in the cultures at the low and high seeding densities (respectively, X(0)=1.0x10(3) and 2.0x10(5) cells/cm(2)). In the culture at the low seeding density, an increase in confluence degree accompanied a decrease in growth potential (R(p)), being R(p)=0.85 and 0.11 at t=48 and 672 h, respectively. Myoblasts seeded at the high density resulted in the immediate cessation of growth with keeping the low range of R(p)=0.02-0.09 throughout the culture. The reduction of R(p) led to the generation of three subpopulations of cells in proliferative, quiescent and differentiated states. Close cell contacts in the confluent state of high seeding culture induced cell quiescence to a higher extent with suppressing differentiation. PMID: 20159584 [PubMed - indexed for MEDLINE] | | |
| Heat treatment of electrospun silicate fiber substrates enhances cellular adhesion and proliferation.
May 19, 2010 at 6:26 AM
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| | Heat treatment of electrospun silicate fiber substrates enhances cellular adhesion and proliferation. J Biosci Bioeng. 2010 Mar;109(3):304-6 Authors: Yamaguchi T, Sakai S, Watanabe R, Tarao T, Kawakami K Synthetic scaffolds support cell attachment in vitro. We prepared ultra-fine silicate fibers using the sol-gel process and electrospinning, heated the fibers to 500 degrees C and investigated their effects on the behavior of human hepatocellular carcinoma (HepG2) cells. Alterations in surface composition following heat treatment improved cell adhesion and influenced cell migration. PMID: 20159582 [PubMed - indexed for MEDLINE] | | |
| Regenerative medicine for craniomaxillofacial surgery.
May 19, 2010 at 6:26 AM
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| | Regenerative medicine for craniomaxillofacial surgery. Oral Maxillofac Surg Clin North Am. 2010 Feb;22(1):33-42 Authors: Costello BJ, Shah G, Kumta P, Sfeir CS Regenerative medicine has recently seen much activity in basic and translational research. These advances are now making their way into surgical practice. A convergence of technologies has afforded opportunities previously not available with conventional surgical reconstructive techniques. Patients requiring complex reconstructive surgery in the craniomaxillofacial region typically benefit from local or regional flaps, nonvascularized grafts, microvascular tissue transfer, or substitute alloplastic materials to restore function and form. In these clinical situations, grafting procedures or alloplastic substitute materials provide best-case replacements for resected, injured, or congenitally missing tissues. However, ideal reconstructive goals, such as a complete return to original form and function, are frequently not completely achieved. Regenerative techniques now in clinical use and at the translational research stage hold promise for custom-tailored constructs! with the potential to regenerate tissue in the host without significant donor site morbidity. These techniques may provide better structure, aesthetics, and function than the best currently available options. This article presents the latest concepts in craniomaxillofacial regenerative medicine and reviews the multipronged approach to restoring architecture using novel "smart" multifunctional scaffolds, cellular technologies, growth factors, and other novel regenerative medical strategies. PMID: 20159476 [PubMed - indexed for MEDLINE] | | | | 
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