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| Bad Link Fixed
March 9, 2010 at 6:56 PM
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| | A bad link to the "extraordinary petition" mentioned in the item below has been fixed. | | |
| $50 Million Clinical Trial Effort Proposed to CIRM Directors
March 9, 2010 at 12:44 PM
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| The California stem cell agency has released additional information on its proposed, first-ever funding round for participation in clinical trials.
The plan, expected to be approved on Thursday by directors, would provide $50 million for one or two trials and would be limited to "novel cell therapies from pluripotent stem cells." Both businesses and non-profit institutions could compete, but | | |
| Howlers: Loud as Thunder
March 9, 2010 at 11:47 AM
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| From time to time, we have discussed the media and its behavior in connection with the California stem cell agency.
The other day, we ran across an apt, media-related commentary in Barbara Kingsolver's new novel, "The Lacuna."
The remark was offered by one of her characters during a discussion of newspapers with Leon Trotsky in Mexico prior to World War II. One could say that it still applies | | |
| Communications Subcommittee Meeting Delayed
March 9, 2010 at 11:44 AM
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| The California stem cell agency yesterday postponed the first meeting of the directors new subcommittee aimed at improving communications with the public.
CIRM Chairman Robert Klein cancelled the session for personal reasons, the agency said. The session has not yet been rescheduled. | | |
| An effective serum- and xeno-free chemically defined freezing procedure for human embryonic and induced pluripotent stem cells.
March 9, 2010 at 7:01 AM
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| | An effective serum- and xeno-free chemically defined freezing procedure for human embryonic and induced pluripotent stem cells. Hum Reprod. 2010 Mar 5; Authors: Holm F, Ström S, Inzunza J, Baker D, Strömberg AM, Rozell B, Feki A, Bergström R, Hovatta O BACKGROUND Both human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) bear a great potential in regenerative medicine. In addition to optimized clinical grade culture conditions, efficient clinical grade cryopreservation methods for these cells are needed. Obtaining good survival after thawing has been problematic. METHODS We used a novel, chemically defined effective xeno-free cryopreservation system for cryostorage and banking of hESCs and iPSCs. The earlier established slow freezing protocols have, even after recent improvements, resulted in low viability and thawed cells had a high tendency to differentiate. The medium is a completely serum and animal substance free product containing dimethylsulfoxide, anhydrous dextrose and a polymer as cryoprotectants. The cells were directly frozen at -70 degrees C, without a programmed freezer. RESULTS The number of frozen colonies versus the number of surviving colonies differed significantly for ! both HS293 (chi(2) = 9.616 with one degree of freedom and two-tailed P = 0.0019) and HS306 (chi(2) = 8.801 with one degree of freedom and two-tailed P = 0.0030). After thawing, the cells had a high viability (90-96%) without any impact on proliferation and differentiation, compared with the standard freezing procedure where viability was much lower (49%). The frozen-thawed hESCs and iPSCs had normal karyotype and maintained properties of pluripotent cells with corresponding morphological characteristics, and expressed pluripotency markers after 10 passages in culture. They formed teratomas containing tissue components of the three germ layers. CONCLUSION The defined freezing-thawing system described here offers an excellent simple option for banking of hESCs and iPSCs. PMID: 20208061 [PubMed - as supplied by publisher] | | |
| Effects of Cannabinor, a Novel Selective Cannabinoid 2 Receptor Agonist, on Bladder Function in Normal Rats.
March 9, 2010 at 7:01 AM
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| | Effects of Cannabinor, a Novel Selective Cannabinoid 2 Receptor Agonist, on Bladder Function in Normal Rats. Eur Urol. 2010 Mar 1; Authors: Gratzke C, Streng T, Stief CG, Downs TR, Alroy I, Rosenbaum JS, Andersson KE, Hedlund P BACKGROUND: Cannabinoid (CB) receptors may be involved in the control of bladder function; the role of CB receptor subtypes in micturition has not been established. OBJECTIVES: Our aim was to evaluate the effects of cannabinor, a novel CB2 receptor agonist, on rat bladder function. DESIGN, SETTING, AND PARTICIPANTS: Sprague Dawley rats were used. Distribution of CB2 receptors in sensory and cholinergic nerves of the detrusor was studied. Selectivity of cannabinor for human and rat CB receptors was evaluated. Effects of cannabinor on rat detrusor and micturition were investigated. MEASUREMENTS: Immunohistochemistry, radioligand binding, tritium outflow assays, organ bath studies of isolated bladder tissue, and cystometry in awake rats were used. RESULTS AND LIMITATIONS: CB2 receptor immunoreactivity was expressed in the urothelium and in sensory and cholinergic bladder nerves. Cannabinor exhibited similar binding at human and rat CB2 receptors and a 321-fold functi! onal selectivity for the CB2 receptor versus the CB1 receptor. Cannabinor had no effect on isolated detrusor muscle function. In vivo, cannabinor 3.0mg/kg increased micturition intervals and volumes by 52% (p<0.05) and 96% (p<0.01), respectively, and increased threshold and flow pressures by 73% (p<0.01) and 49% (p<0.001), respectively. Cannabinor 0.3 or 1.0mg/kg or vehicle did not affect urodynamic parameters. CONCLUSIONS: Considering that CB2 receptors are localized on sensory nerves and on the urothelium and that cannabinor had effects on "afferent" urodynamic parameters, peripheral CB2 receptors may be involved in sensory functions of rat micturition. Effects of cannabinor on cholinergic nerve activity in normal bladder tissue appear to be limited. PMID: 20207474 [PubMed - as supplied by publisher] | | |
| Distinct Hematopoietic Stem Cell Subtypes Are Differentially Regulated by TGF-beta1.
March 9, 2010 at 7:01 AM
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| | Distinct Hematopoietic Stem Cell Subtypes Are Differentially Regulated by TGF-beta1. Cell Stem Cell. 2010 Mar 5;6(3):265-278 Authors: Challen GA, Boles NC, Chambers SM, Goodell MA The traditional view of hematopoiesis has been that all the cells of the peripheral blood are the progeny of a unitary homogeneous pool of hematopoietic stem cells (HSCs). Recent evidence suggests that the hematopoietic system is actually maintained by a consortium of HSC subtypes with distinct functional characteristics. We show here that myeloid-biased HSCs (My-HSCs) and lymphoid-biased HSCs (Ly-HSCs) can be purified according to their capacity for Hoechst dye efflux in combination with canonical HSC markers. These phenotypes are stable under natural (aging) or artificial (serial transplantation) stress and are exacerbated in the presence of competing HSCs. My- and Ly-HSCs respond differently to TGF-beta1, presenting a possible mechanism for differential regulation of HSC subtype activation. This study demonstrates definitive isolation of lineage-biased HSC subtypes and contributes to the fundamental change in view that the hematopoietic system is maintained by ! a continuum of HSC subtypes, rather than a functionally uniform pool. PAPERFLICK: PMID: 20207229 [PubMed - as supplied by publisher] | | |
| G-CSF Promotes the Proliferation of Developing Cardiomyocytes In Vivo and in Derivation from ESCs and iPSCs.
March 9, 2010 at 7:01 AM
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| | G-CSF Promotes the Proliferation of Developing Cardiomyocytes In Vivo and in Derivation from ESCs and iPSCs. Cell Stem Cell. 2010 Mar 5;6(3):227-237 Authors: Shimoji K, Yuasa S, Onizuka T, Hattori F, Tanaka T, Hara M, Ohno Y, Chen H, Egasgira T, Seki T, Yae K, Koshimizu U, Ogawa S, Fukuda K During a screen for humoral factors that promote cardiomyocyte differentiation from embryonic stem cells (ESCs), we found marked elevation of granulocyte colony-stimulating factor receptor (G-CSFR) mRNA in developing cardiomyocytes. We confirmed that both G-CSFR and G-CSF were specifically expressed in embryonic mouse heart at the midgestational stage, and expression levels were maintained throughout embryogenesis. Intrauterine G-CSF administration induced embryonic cardiomyocyte proliferation and caused hyperplasia. In contrast, approximately 50% of csf3r(-/-) mice died during late embryogenesis because of the thinning of atrioventricular walls. ESC-derived developing cardiomyocytes also strongly expressed G-CSFR. When extrinsic G-CSF was administered to the ESC- and human iPSC-derived cardiomyocytes, it markedly augmented their proliferation. Moreover, G-CSF-neutralizing antibody inhibited their proliferation. These findings indicated that G-CSF is critically in! volved in cardiomyocyte proliferation during development, and may be used to boost the yield of cardiomyocytes from ESCs for their potential application to regenerative medicine. PMID: 20207226 [PubMed - as supplied by publisher] | | |
| Controlled-size embryoid body formation in concave microwell arrays.
March 9, 2010 at 7:01 AM
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| | Controlled-size embryoid body formation in concave microwell arrays. Biomaterials. 2010 Mar 4; Authors: Choi YY, Chung BG, Lee DH, Khademhosseini A, Kim JH, Lee SH Embryonic stem (ES) cells hold great potential as a renewable cell source for regenerative medicine and cell-based therapy. Despite the potential of ES cells, conventional stem cell culture methods do not enable the control of the microenvironment. A number of microscale engineering approaches have been recently developed to control the extracellular microenvironment and to direct embryonic stem cell fate. Here, we used engineered concave microwell arrays to regulate the size and shape of embryoid bodies (EBs)-cell aggregate intermediates derived from ES cells. Murine ES cells were aggregated within concave microwells, and their aggregate sizes were controlled by varying the microwell widths (200, 500, and 1000 mum). Differentiation of murine ES cells into three germ layers was assessed by analyzing gene expression. We found that ES cell-derived cardiogenesis and neurogenesis were strongly regulated by the EB size, showing that larger concave microwell arrays indu! ced more neuronal and cardiomyocyte differentiation than did smaller microwell arrays. Therefore, this engineered concave microwell array could be a potentially useful tool for controlling ES cell behavior. PMID: 20206991 [PubMed - as supplied by publisher] | | |
| The effects of controlled HGF delivery from an affinity-binding alginate biomaterial on angiogenesis and blood perfusion in a hindlimb ischemia model.
March 9, 2010 at 7:01 AM
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| | The effects of controlled HGF delivery from an affinity-binding alginate biomaterial on angiogenesis and blood perfusion in a hindlimb ischemia model. Biomaterials. 2010 Mar 4; Authors: Ruvinov E, Leor J, Cohen S Enhancing tissue self-repair through the use of active acellular biomaterials is one of the main goals of regenerative medicine. We now describe the features of an injectable alginate biomaterial designed to affinity-bind heparin-binding proteins and release them at a rate reflected by their association constant to alginate-sulfate. The interactions of hepatocyte growth factor (HGF) with alginate-sulfate resulted in factor protection from proteolysis, as shown by mass spectroscopy analysis after trypsin digestion. When the HGF/alginate-sulfate bioconjugate was incorporated into alginate hydrogel, HGF release was sustained by a factor of 3, as compared to the release rate from non-modified hydrogel. The released factor retained activity, as shown by its induction of ERK1/2 activation and affording cytoprotection in rat neonatal cardiomyocyte cultures. In vivo, an injectable form of the affinity-binding alginate system extended by 10-fold, as compared to a saline-tr! eated group, retention of HGF in myocardial tissue when delivered immediately after myocardial infarction. In a severe murine hindlimb ischemia model, HGF delivery from the affinity-binding system improved tissue blood perfusion and induced mature blood vessel network formation. The therapeutic efficacy of the affinity-binding system, as well as its ease of delivery by injection, provides a proof-of-concept for the potential use of this bioactive biomaterial strategy in cardiovascular repair. PMID: 20206988 [PubMed - as supplied by publisher] | | |
| Phosphatidylserine immobilization of lentivirus for localized gene transfer.
March 9, 2010 at 7:01 AM
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| | Phosphatidylserine immobilization of lentivirus for localized gene transfer. Biomaterials. 2010 Mar 3; Authors: Shin S, Tuinstra HM, Salvay DM, Shea LD Localized and efficient gene transfer can be promoted by exploiting the interaction between the vector and biomaterial. Regulation of the vector-material interaction was investigated by capitalizing on the binding between lentivirus and phosphatidylserine (PS), a component of the plasma membrane. PS was incorporated into microspheres composed of the copolymers of lactide and glycolide (PLG) using an emulsion process. Increasing the weight ratio of PS to PLG led to a greater incorporation of PS. Lentivirus, but not adenovirus, associated with PS-PLG microspheres, and binding was specific to PS relative to PLG alone or PLG modified with phosphatidylcholine. Immobilized lentivirus produced large numbers of transduced cells, and increased transgene expression relative to virus alone. Microspheres were subsequently formed into porous tissue engineering scaffolds, with retention of lentivirus binding. Lentivirus immobilization resulted in long-term and localized express! ion within a subcutaneously implanted scaffold. Microspheres were also formed into multiple channel bridges for implantation into the spinal cord. Lentivirus delivery from the bridge produced maximal expression at the implant and a gradient of expression rostrally and caudally. This specific binding of lentiviral vectors to biomaterial scaffolds may provide a versatile tool for numerous applications in regenerative medicine or within model systems that investigate tissue development. PMID: 20206382 [PubMed - as supplied by publisher] | | |
| The optimization of porous polymeric scaffolds for chondrocyte/atelocollagen based tissue-engineered cartilage.
March 9, 2010 at 7:01 AM
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| | The optimization of porous polymeric scaffolds for chondrocyte/atelocollagen based tissue-engineered cartilage. Biomaterials. 2010 Mar 3; Authors: Tanaka Y, Yamaoka H, Nishizawa S, Nagata S, Ogasawara T, Asawa Y, Fujihara Y, Takato T, Hoshi K To broaden the clinical application of cartilage regenerative medicine, we should develop an implant-type tissue-engineered cartilage with firmness and 3-D structure. For that, we attempted to use a porous biodegradable polymer scaffold in the combination with atelocollagen hydrogel, and optimized the structure and composition of porous scaffold. We administered chondrocytes/atelocollagen mixture into the scaffolds with various kinds of porosities (80-95%) and pore sizes (0.3-2.0 mm), consisting of PLLA or related polymers (PDLA, PLA/CL and PLGA), and transplanted the constructs in the subcutaneous areas of nude mice. The constructs using scaffolds of excessively large pore sizes (>1 mm) broke out on the skin and impaired the host tissue. The scaffold with the porosity of 95% and pore size of 0.3 mm could effectively retain the cells/gel mixture and indicated a fair cartilage regeneration. Regarding the composition, the tissue-engineered cartilage was superior ! in PLGA and PLLA to that in PLA/CA and PDLA. The latter two showed the dense accumulation of macrophages, which may deteriorate the cartilage regeneration. Although PLGA or PLLA has been currently recommended for the scaffold of cartilage, the polymer for which biodegradation was exactly synchronized to the cartilage regeneration would improve the quality of the tissue-engineered cartilage. PMID: 20206380 [PubMed - as supplied by publisher] | | |
| Runx1 Isoforms Show Differential Expression Patterns During Hematopoietic Development But Have Similar Functional Effects in Adult Hematopoietic Stem Cells.
March 9, 2010 at 7:01 AM
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| | Runx1 Isoforms Show Differential Expression Patterns During Hematopoietic Development But Have Similar Functional Effects in Adult Hematopoietic Stem Cells. Exp Hematol. 2010 Mar 2; Authors: Challen GA, Goodell MA OBJECTIVE: RUNX1/AML1 is an essential regulator of hematopoiesis and has multiple isoforms arising from differential splicing and utilization of two promoters. We hypothesized that the rare Runx1c isoform has a distinct role in hematopoietic stem cells (HSCs). METHODS: We have characterized the expression pattern of Runx1c in mouse embryos and human embryonic stem cell (hESC)-derived embryoid bodies using in situ hybridization, and expression levels in mouse and human HSCs by real-time PCR. We then determined the functional effects of Runx1c using enforced retroviral over-expression in mouse HSCs. RESULTS: We observed differential expression profiles of RUNX1 isoforms during hematopoietic differentiation of hESCs. The RUNX1a and RUNX1b isoforms were expressed consistently throughout hematopoietic differentiation whereas the RUNX1c isoform was only expressed at the time of emergence of definitive HSCs. RUNX1c was also expressed in the AGM region of E10.5-11.5 mouse! embryos, the region where definitive HSCs arise. These observations suggested that the RUNX1c isoform may be important for the specification or function of definitive HSCs. However, using retroviral over-expression to study the effect of RUNX1 isoforms on HSCs in a gain-of-function system, no discernable functional difference could be identified between RUNX1 isoforms in mouse HSCs. Over-expression of both RUNX1b and RUNX1c induced quiescence in mouse HSCs in vitro and in vivo. CONCLUSIONS: Although the divergent expression profiles of Runx1 isoforms during development suggest specific roles for these proteins at different stages of HSC maturation, we could not detect an important functional distinction in adult mouse HSCs using our assay systems. PMID: 20206228 [PubMed - as supplied by publisher] | | |
| Inflammation, Immunity, and Alzheimer's Disease.
March 9, 2010 at 7:01 AM
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| | Inflammation, Immunity, and Alzheimer's Disease. CNS Neurol Disord Drug Targets. 2010 Mar 6; Authors: Town T Few topics in the field of Alzheimer's disease (AD) research have brought about the level of excitement and interest as the role of inflammation and immunity in the pathobiology and treatment of the disease. In this special issue of the journal, experts in the field give their views on how inflammatory processes and the immune system intersect- at both etiological and treatment levels- with disease biology. Collectively, nearly three decades of work are covered in this special issue, beginning with the first epidemiologic studies that showed an inverse risk relationship between AD and use of non-steroidal anti-inflammatory drugs, and ending with "immunotherapy" approaches and recent studies examining the roles of innate immune cells including microglia and peripheral mononuclear phagocytes in AD. Despite considerable work in this area, many important questions remain concerning the nature and timing of immune/inflammatory responses in the context of AD, and at wha! t point and how to therapeutically intervene. PMID: 20205648 [PubMed - as supplied by publisher] | | |
| Encapsulation of Curcumin in Pluronic Block Copolymer Micelles for Drug Delivery Applications.
March 9, 2010 at 6:56 AM
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| | Encapsulation of Curcumin in Pluronic Block Copolymer Micelles for Drug Delivery Applications. J Biomater Appl. 2010 Mar 5; Authors: Sahu A, Kasoju N, Goswami P, Bora U We report here the potential of Pluronic tri-block copolymer micelles for the formulation of curcumin, a natural dietary compound having great therapeutic potential against many diseases including cancer. Two most commonly used Pluronic F127 and F68 were used for the formulation and analyzed for curcumin encapsulation efficiency and stability. The encapsulation of drug in micelle was highly dependent on drug-to-copolymer ratio. Pluronic F127 showed better encapsulation efficiency than Pluronic F68. In vitro release profile demonstrated slower and sustained release of curcumin from Pluronic micelles. The lyophilized form of the formulations exhibited good stability for long-term storage. The physical interaction of curcumin with Pluronic was evident by XRD analysis, UV-visible, fluorescence, and FT-IR spectroscopy. AFM study showed that the drug-encapsulated micelles were spherical in shape with diameters below 100 nm. The in vitro cytotoxicity of the drug formulat! ions was investigated with HeLa cancer cells. Pluronic-encapsulated curcumin showed comparable anticancer activity with free curcumin. PMID: 20207782 [PubMed - as supplied by publisher] | | |
| Biocompatibility of Osteogenic Predifferentiated Human Cord Blood Stem Cells with Biomaterials and the Influence of the Biomaterial on the Process of Differentiation.
March 9, 2010 at 6:56 AM
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| | Biocompatibility of Osteogenic Predifferentiated Human Cord Blood Stem Cells with Biomaterials and the Influence of the Biomaterial on the Process of Differentiation. J Biomater Appl. 2010 Mar 5; Authors: Naujoks C, Langenbach F, Berr K, Depprich R, Kübler N, Meyer U, Handschel J, Kögler G Modern cell-based bone reconstruction therapies offer new therapeutic opportunities and tissue engineering represents a more biological-oriented approach to heal bone defects of the skeleton. Human unrestricted somatic stem cells (USSCs) derived form umbilical cord blood offer new promising aspects e.g., can differentiate into osteogenetic cells. Furthermore these cells have fewer ethical and legal restrictions compared to embryonic stem cells (ESCs). The purpose of this study was to evaluate the compatibility of osteogenic pre-differentiated USSCs with various biomaterials and to address the question, whether biomaterials influence the process of differentiation of the USSCs. After osteogenic differentiation with DAG USSCs were cultivated with various biomaterials. To asses the biocompatibility of USSCs the attachment and the proliferation of the cells on the biomaterial were measured by a CyQUANT(R) assay, the morphology was analyzed by scanning electron microsc! opy and the influence of the gene expression was analyzed by real time PCR. Our results provide evidence that insoluble collagenous bone matrix followed by beta-tricalciumphosphate is highly suitable for bone tissue engineering regarding cell attachment and proliferation. The gene expression analysis indicates that biomaterials influence the gene expression of USSCs. These results are in concordance with our previous study with ESCs. PMID: 20207776 [PubMed - as supplied by publisher] | | |
| Biocompatibility and Antibacterial Effect of Silver Doped 3d-Glass-Ceramic Scaffolds for Bone Grafting.
March 9, 2010 at 6:56 AM
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| | Biocompatibility and Antibacterial Effect of Silver Doped 3d-Glass-Ceramic Scaffolds for Bone Grafting. J Biomater Appl. 2010 Mar 5; Authors: Balagna C, Vitale-Brovarone C, Miola M, Verne E, Canuto RA, Saracino S, Muzio G, Fucale G, Maina G A 3D-glass-ceramic scaffold for bone tissue engineering with an interconnected macroporous network of pores was doped with silver ions in order to confer antibacterial properties. For this purpose, silver ions were selectively added to the scaffold surfaces through ion-exchange using an aqueous silver nitrate solution. The silver-doped scaffolds were characterized by means of leaching, in vitro antibacterial, and citotoxicity tests. In particular, the silver effect was examined through a broth dilution test in order to evaluate the proliferation of bacteria by counting the colonies forming units. Moreover, cytotoxicity tests were carried out to understand the effect of silver-containing scaffolds on cell adhesion, proliferation, and vitality. For all tests a comparison between silver-doped scaffold and silver-doped scaffold dry sterilized was performed. PMID: 20207775 [PubMed - as supplied by publisher] | | |
| The cytoskeletal organization of breast carcinoma and fibroblast cells inside three dimensional (3-D) isotropic silicon microstructures.
March 9, 2010 at 6:56 AM
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| | The cytoskeletal organization of breast carcinoma and fibroblast cells inside three dimensional (3-D) isotropic silicon microstructures. Biomaterials. 2010 Mar 5; Authors: Nikkhah M, Strobl JS, De Vita R, Agah M Studying the cytoskeletal organization as cells interact in their local microenvironment is interest of biological science, tissue engineering and cancer diagnosis applications. Herein, we describe the behavior of cell lines obtained from metastatic breast tumor pleural effusions (MDA-MB-231), normal fibrocystic mammary epithelium (MCF10A), and HS68 normal fibroblasts inside three dimensional (3-D) isotropic silicon microstructures fabricated by a single-mask, single-isotropic-etch process. We report differences in adhesion, mechanism of force balance within the cytoskeleton, and deformability among these cell types inside the 3-D microenvironment. HS68 fibroblasts typically stretched and formed vinculin-rich focal adhesions at anchor sites inside the etched cavities. In contrast, MCF10A and MDA-MB-231 cells adopted the curved surfaces of isotropic microstructures and exhibited more diffuse vinculin cytoplasmic staining in addition to vinculin localized in focal a! dhesions. The measurement of cells elasticity using atomic force microscopy (AFM) indentation revealed that HS68 cells are significantly stiffer (p < 0.0001) than MCF10A and MDA-MB-231 cells. Upon microtubule disruption with nocodazole, fibroblasts no longer stretched, but adhesion of MCF10A and MDA-MB-231 within the etched features remained unaltered. Our findings are consistent with tensegrity theory. The 3-D microstructures have the potential to probe cytoskeletal-based differences between healthy and diseased cells that can provide biomarkers for diagnostics purposes. PMID: 20207413 [PubMed - as supplied by publisher] | | |
| Modulation of polycaprolactone composite properties through incorporation of mixed phosphate glass formulations.
March 9, 2010 at 6:56 AM
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| | Modulation of polycaprolactone composite properties through incorporation of mixed phosphate glass formulations. Acta Biomater. 2010 Mar 3; Authors: Mohammadi MS, Ahmed I, Marelli B, Rudd C, Bureau MN, Nazhat SN Phosphate-based glasses (PGs) and their composites are of interest as bone repair and tissue engineering scaffolds due to the totally degradable nature of the materials. This study investigated the effect of Si and Fe on the properties of PG particulate-filled polycaprolactone (PCL) matrix composites. Two glass compositions were investigated (in mol%): 50 P(2)O(5), 40 CaO and 10 SiO(2) or Fe(2)O(3) (Si(10) and Fe(10) respectively). All composites contained 40 vol% particulate filler, either of Si(10), Fe(10), or a blend (40Si(10)/0Fe(10), 30Si(10)/10Fe(10), 20Si(10)/20Fe(10), 10Si(10)/30Fe(10), 0Si(10)/40Fe(10)). Ion release, weight loss and composite mechanical properties were characterized as a function of time in deionised water (DW) and phosphate buffered saline (PBS), respectively. The potential for calcium phosphate deposition was assessed in simulated body fluid (SBF). Calcium and phosphate ions released in DW increased in tandem with the rate of composite ! weight loss, which increased with Si(10) content. A Si(10) content dependent rate of pH reduction was observed in DW. At day 56, PG in 40Si(10)/0Fe(10) composite completely dissolved, whereas 67% of the 0Si(10)/40Fe(10) remained. The initial flexural strength of 40Si(10)/0Fe(10) composites was significantly lower when compared to the other materials. An increase in Si(10) content led to an increase in Young's modulus and a concomitant decrease in flexural strain. It was found that the PCL molecular weight (M(w)) was dramatically decreased with an increase in Si(10) content. FTIR analysis showed that Si incorporation into PG led to their reaction with the PCL ester bonds resulting in a reduction in PCL M(w) when processed at elevated temperatures. Changes in mechanical properties with time in PBS were glass blend dependent and a more rapid rate of reduction was observed in Si(10) dominant composites. At day 28 in SBF, surface deposited brushite was formed in 20Si(10)/20Fe(10! ) PG containing composites. Therefore the properties of PCL-PG! composi tes could be tailored by controlling the phosphate glass blend composition. PMID: 20206722 [PubMed - as supplied by publisher] | | |
| Beta-tricalcium phosphate exerts osteo-conductivity through alpha2beta1 integrin and down-stream MAPK/ERK signaling pathway.
March 9, 2010 at 6:56 AM
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| | Beta-tricalcium phosphate exerts osteo-conductivity through alpha2beta1 integrin and down-stream MAPK/ERK signaling pathway. Biochem Biophys Res Commun. 2010 Mar 3; Authors: Lu Z, Zreiqat H Beta-tricalcium phosphate (beta-TCP) has been clinically used as a bone graft substitute for decades because its excellent osteo-conductivity. However, the exact mechanism(s) by which beta-TCP exerts osteo-conductivity are not fully documented. This study was aimed to investigate the molecular mechanism(s) by which beta-TCP modulates the biological response of primary human osteoblasts (HOBs). It was showed that HOBs seeded into the beta-TCP scaffolds expressed significantly higher levels of osteogenic genes, compared to those cultured on tissue culture plastic; meanwhile these cells showed 7-fold increase in alpha2 integrin subunit gene expression and the activation of MAPK/ERK signaling pathway. In addition, the osteogenic conduction by beta-TCP scaffolds was attenuated directly by inhibiting the mitogen activated protein kinase (MAPK)/extracellular related kinase (ERK) signaling pathway or indirectly by blocking the alpha2beta1 integrin signaling pathway. We co! ncluded that beta-TCP scaffold exerts osteo-conductivity through alpha2beta1 integrin and down-stream MAPK/ERK signaling pathway, suggesting a feasible approach to consider when designing or fabricating the scaffolds for bone tissue engineering. PMID: 20206607 [PubMed - as supplied by publisher] | | |
| Differentiation of mouse embryonic stem cells into dental epithelial-like cells induced by ameloblasts serum-free conditioned medium.
March 9, 2010 at 6:56 AM
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| | Differentiation of mouse embryonic stem cells into dental epithelial-like cells induced by ameloblasts serum-free conditioned medium. Biochem Biophys Res Commun. 2010 Mar 3; Authors: Ning F, Guo Y, Tang J, Zhou J, Zhang H, Lu W, Gao Y, Wang L, Pei D, Duan Y, Jin Y Embryonic stem cells (ESCs) possess an intrinsic self-renewal ability and can differentiate into numerous types of functional tissue cells; however, whether ESCs can differentiate toward the odontogenic lineage is still unknown. In this study, we developed an efficient culture strategy to induce the differentiation of murine ESCs (mESCs) into dental epithelial cells. By culturing mESCs in ameloblasts serum-free conditioned medium (ASF-CM), we could induce their differentiation toward dental epithelial cell lineages; however, similar experiments with the tooth germ cell conditioned medium (TGC-CM) did not yield effective results. After culturing the cells for 14 days in the differentiation-inducing media, the expression of ameloblast-specific proteins such as cytokeratin (CK)14, ameloblastin (AMBN), and amelogenin (AMGN) was markedly higher in mESCs obtained with embryoid body (EB) formation than in mESCs obtained without EB formation. We observed that immunocompro! mised mice implanted with induced murine EBs (mEBs) showed tissue regenerative capacity and produced odontogenic epithelial-like structures, whereas those implanted with mSCE monolayer cells mainly formed connective tissues. Thus, for the first time, we report that ASF-CM provides a suitable microenvironment for inducing mESC differentiation along the odontogenic epithelial cell lineage. This result has important implications for tooth tissue engineering. PMID: 20206604 [PubMed - as supplied by publisher] | | |
| Phosphatidylserine immobilization of lentivirus for localized gene transfer.
March 9, 2010 at 6:56 AM
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| | Phosphatidylserine immobilization of lentivirus for localized gene transfer. Biomaterials. 2010 Mar 3; Authors: Shin S, Tuinstra HM, Salvay DM, Shea LD Localized and efficient gene transfer can be promoted by exploiting the interaction between the vector and biomaterial. Regulation of the vector-material interaction was investigated by capitalizing on the binding between lentivirus and phosphatidylserine (PS), a component of the plasma membrane. PS was incorporated into microspheres composed of the copolymers of lactide and glycolide (PLG) using an emulsion process. Increasing the weight ratio of PS to PLG led to a greater incorporation of PS. Lentivirus, but not adenovirus, associated with PS-PLG microspheres, and binding was specific to PS relative to PLG alone or PLG modified with phosphatidylcholine. Immobilized lentivirus produced large numbers of transduced cells, and increased transgene expression relative to virus alone. Microspheres were subsequently formed into porous tissue engineering scaffolds, with retention of lentivirus binding. Lentivirus immobilization resulted in long-term and localized express! ion within a subcutaneously implanted scaffold. Microspheres were also formed into multiple channel bridges for implantation into the spinal cord. Lentivirus delivery from the bridge produced maximal expression at the implant and a gradient of expression rostrally and caudally. This specific binding of lentiviral vectors to biomaterial scaffolds may provide a versatile tool for numerous applications in regenerative medicine or within model systems that investigate tissue development. PMID: 20206382 [PubMed - as supplied by publisher] | | |
| Structure-Function Characteristics of the Biomaterials based on Milk-derived Proteins.
March 9, 2010 at 6:56 AM
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| | Structure-Function Characteristics of the Biomaterials based on Milk-derived Proteins. Int J Biol Macromol. 2010 Mar 2; Authors: Ghosh A, Ali MA, Selvanesan L, Dias GJ There is an impetus on development of implantable biomaterials with the characteristics of improved biodegradability, bio-absorbability and wound healing activities. The milk proteins have valuable nutritional and biological properties, which lead to the promotion of quality health. In this study, whey protein isolate or WPI (highly aggregated) and its component lactalbumin (less aggregated) were melt blended with polycaprolactone (PCL) and then compression moulded into thin sheets ( approximately 1mm thickness). The effects of structural morphologies of the proteins on the mechanical, morphological, in-vitro enzymatic degradation, and cytotoxicity and cell proliferation characteristics of the biomaterials were examined. In general, the tensile strength and modulus of the biomaterials decreased with increasing protein content. Compared to WPI, lactalbumin showed a better compatibility with the PCL matrix as observed in the mechanical properties and scanning electr! on microscopic morphology. The biomaterials exhibited a good retention of the mechanical characteristics after digestion in a physiologically simulated fluid containing trypsin enzyme. However, lactalbumin containing biomaterials showed a better retention of the tensile properties compared to WPI containing biomaterials. The cell culture studies indicated that the biomaterials have no cytotoxic effects, moreover they enhanced the proliferation of L929 cells compared to the pure PCL. Finally, this study indicated that the PCL based biomaterials with a protein content of 20 wt% may be applied in fabrication of implantable devices for soft tissue engineering, where it requires a reasonably low to moderate mechanical strength (e.g., approximately 10 MPa tensile strength), and improved biodegradability, biocompatibility and tissue healing activities. PMID: 20206202 [PubMed - as supplied by publisher] | | |
| Development of a rapid culture method to induce adipocyte differentiation of human bone marrow-derived mesenchymal stem cells.
March 9, 2010 at 6:56 AM
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| | Development of a rapid culture method to induce adipocyte differentiation of human bone marrow-derived mesenchymal stem cells. Biochem Biophys Res Commun. 2010 Mar 2; Authors: Ninomiya Y, Sugahara-Yamashita Y, Nakachi Y, Tokuzawa Y, Okazaki Y, Nishiyama M Human mesenchymal stem cells (hMSCs) derived from bone marrow are multipotent stem cells that can regenerate mesenchymal tissues such as adipose, bone or muscle. It is thought that hMSCs can be utilized as a cell resource for tissue engineering and as human models to study cell differentiation mechanisms, such as adipogenesis, osteoblastogenesis and so on. Since it takes 2-3 weeks for hMSCs to differentiate into adipocytes using conventional culture methods, the development of methods to induce faster differentiation into adipocytes is required. In this study we optimized the culture conditions for adipocyte induction to achieve a shorter cultivation time for the induction of adipocyte differentiation in bone marrow-derived hMSCs. Briefly, we used a cocktail of dexamethasone, insulin, metylisobutylxanthine (DIM) plus a peroxisome proliferator-activated receptor gamma agonist, rosiglitazone (DIMRo) as a new adipogenic differentiation medium. We successfully shorten! ed the period of cultivation to 7-8 days from 2-3 weeks. We also found that rosiglitazone alone was unable to induce adipocyte differentiation from hMSCs in vitro. However, rosiglitazone appears to enhance hMSC adipogenesis in the presence of other hormones and/or compounds, such as DIM. Furthermore, the inhibitory activity of TGF on adipogenesis could be investigated using DIMRo-treated hMSCs. We conclude that our rapid new culture method is very useful in measuring the effect of molecules that affect adipogenesis in hMSCs. PMID: 20206132 [PubMed - as supplied by publisher] | | | | 
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