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| Establishment and characterization of human embryonic stem cell lines, Turkey perspectives.
March 30, 2010 at 6:31 AM
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| | Establishment and characterization of human embryonic stem cell lines, Turkey perspectives. In Vitro Cell Dev Biol Anim. 2010 Mar 27; Authors: Candan ZN, Kahraman S Human embryonic stem cells (hESC), which are derived from the inner cell mass (ICM) of blastocyst stage embryos, are of great importance because of their unpredictable two unique features: their differentiation ability into all types of cells derived from three germ layers and their potentially unlimited capacity of self renewing with stable karyotype. These distinguished properties make hESC very promising cell source for regenerative medicine, tissue replacement therapies, and drug screening studies as well as genomics. However, due to the several technical problems, such as risk of teratoma formation, immune response, and unknown genetic pathways for lineage specific differentiation, and ethical drawbacks of their using in clinical treatments, hESC researches are still waiting to advance beyond to animal trials and drug studies. During the last decade, more than 300 new hESC lines have been derived and published by researchers worldwide. However, despite their ! similar well-known unique properties, recent studies reported that hESC lines have very individual properties and are differed from each other with regards to their differentiation ability and gene expression profiles. Therefore, all hESC lines should be characterized in detail and then registered in a stem cell bank for generating global database. In this report, the characteristic of hESC lines, which were established in Istanbul Memorial Hospital between 2003 and 2005, and derivation methods were described in detail to inform researchers and to facilitate new prospective cooperative studies. PMID: 20349214 [PubMed - as supplied by publisher] | | |
| Growth factor production from fibrin-encapsulated human keratinocytes.
March 30, 2010 at 6:31 AM
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| | Growth factor production from fibrin-encapsulated human keratinocytes. Biotechnol Lett. 2010 Mar 27; Authors: Acevedo CA, Somoza RA, Weinstein-Oppenheimer C, Brown DI, Young ME Fibrin has been used extensively in cell encapsulation because it has important biological properties. Keratinocyte encapsulation in fibrin is a widely used technique in skin tissue engineering. The production of growth factors (EGF, TGF-beta1 and PDGF-BB) was evaluated when keratinocytes are encapsulated in fibrin. Secretions of TGF-beta1 and PDGF-BB increased more than five times compared to monolayer cultures. Encapsulated cells secreted about 80% active form of TGF-beta1 (monolayer cells only secreted inactive form). An enhanced secretion of TGF-beta1 and PDGF-BB was found in encapsulated cells, showing that fibrin capsules are favourable for the production of these growth factors. PMID: 20349112 [PubMed - as supplied by publisher] | | |
| Transcriptome and proteome of dental follicle cells.
March 30, 2010 at 6:31 AM
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| | Transcriptome and proteome of dental follicle cells. J Dent Res. 2010 Mar 26; Authors: Morsczeck C, Schmalz G Ectomesenchymal dental stem cells could be feasible tools for dental tissue engineering. Dental follicle cells are a promising example, since they are capable of differentiation into various dental tissue cells, such as osteoblasts or cementoblasts. However, cellular mechanisms of cell proliferation and differentiation are not understood in detail. Basic knowledge of these molecular processes may shorten the time before ectomesenchymal dental stem cells can be exploited for bone augmentation in regenerative medicine. Recent developments in proteomics and transcriptomics have made information about genome-wide expression profiles accessible, which can aid in clarifying molecular mechanisms of cells. This review describes the transcriptomes and proteomes of dental follicle cells before and after differentiation, and compares them with differentially expressed populations from dental tissue or bone marrow. PMID: 20348482 [PubMed - as supplied by publisher] | | |
| Support of human adipose-derived mesenchymal stem cell multipotency by a poloxamer-octapeptide hybrid hydrogel.
March 30, 2010 at 6:31 AM
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| | Support of human adipose-derived mesenchymal stem cell multipotency by a poloxamer-octapeptide hybrid hydrogel. Biomaterials. 2010 Mar 25; Authors: Wang Y, Zhao L, Hantash BM The development of new biological materials, particularly those capable of serving as permissive substrates for cell growth, differentiation, and biological function, is a key area for advancing medical technology. In this work, we examined the characteristics of a hybrid hydrogel scaffold composed of poloxamer 407 (PO) and the self-assembling oligopeptdide EFK8 in vitro and in vivo. Rheological tests showed that the storage modulus of EFK8-PO increased by 4 orders of magnitude compared to that of EFK8 alone, indicating that EFK8-PO integrates PO's high and tunable mechanical strength and integrity with the superior bioactivity of EFK8. When human adipose-derived mesenchymal stem cells (hAMSCs) were cultured in PO, we observed severe aggregation. Conversely, almost no aggregation was observed in EFK8 or EFK8-PO after 6 days of culture. hAMSC viability in all 3 hydrogels remained above 80% after 2 weeks of culture. EFK8 and EFK8-PO significantly increased hAMSC pro! liferation rates. In addition, EFK8- and EFK8-PO- but not PO encapsulated hAMSCs differentiated into adipocytes or osteoblasts when exposed to appropriate induction medium, suggesting EFK8 supports hAMSC multipotency in vitro. Moreover, only EFK8-PO supported hAMSC engraftment and adipogenic differenitiation post-transplantation into nude mice. Immunohistochemical analysis confirmed the new tissue was human in origin. Our studies show that EFK8-PO maintains improved mechanical properties and bioactivity relative to its individual constituents, supporting its potential use as a stem cell scaffold in soft tissue engineering. PMID: 20347134 [PubMed - as supplied by publisher] | | |
| Incorporation of tripolyphosphate nanoparticles into fibrous poly(lactide-co-glycolide) scaffolds for tissue engineering.
March 30, 2010 at 6:31 AM
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| | Incorporation of tripolyphosphate nanoparticles into fibrous poly(lactide-co-glycolide) scaffolds for tissue engineering. Biomaterials. 2010 Mar 26; Authors: Xie S, Zhu Q, Wang B, Gu H, Liu W, Cui L, Cen L, Cao Y Poly(lactide-co-glycolide) (PLGA) has been widely used for scaffolding materials in tissue engineering. It degrades mainly via hydrolysis of the ester bonds into lactic acid and glycolic acid leading to the decrease in pH of the surrounding microenvironment. The current study was designed to quickly neutralize the acidic degradation products of PLGA fibrous scaffolds by incorporating tripolyphosphate (TPP) nanoparticles into PLGA fibers. A homogeneous mixture of PLGA and TPP was first obtained by water-in-oil emulsion-dispersion followed by freeze-drying. The dried blend was melt-spun to yield fibers which were processed into scaffolds and subsequently immersed into phosphate-buffered saline (PBS) to verify the degradation properties. The pH of the saline was monitored for a duration of 80 days. The amount of TPP was optimized to obtain a PLGA based scaffolds without acidic degradation problems. Cellular compatibility of the modified and pristine scaffolds was eva! luated using rabbit adipose-derived stem cells (rASCs). It was shown that TPP particles within the fibers were roughly 100nm in diameter and mainly located inside fibers instead of on the superficial layer. The acidic degradation of PT-16 and PT-64 (PT-X is termed when the monomer molar ratio of TPP to PLGA was 1:X) was significantly improved as the pH values of their respective solutions were maintained in a well neutralized state during the degradation. PT-64 and PT-16 scaffolds could well support the attachment and proliferation of rASCs. Hence, the incorporation of TPP nanoparticles via an emulsion-dispersion method could be an effective strategy to improve/adjust the acidic degradation of PLGA and further pave the way for clinical applications of such polyesters. PMID: 20347132 [PubMed - as supplied by publisher] | | |
| The role of a recombinant fragment of laminin-332 in integrin alpha3beta1-dependent cell binding, spreading and migration.
March 30, 2010 at 6:31 AM
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| | The role of a recombinant fragment of laminin-332 in integrin alpha3beta1-dependent cell binding, spreading and migration. Biomaterials. 2010 Mar 26; Authors: Yamashita H, Tripathi M, Harris MP, Liu S, Weidow B, Zent R, Quaranta V The extracellular matrix (ECM) is thought to be an essential component of tissue scaffolding and engineering because it fulfills fundamental functions related to cell adhesion, migration, and three-dimensional organization. Natural ECM preparations, however, are challenging to work with because they are comprised of macromolecules that are large and insoluble in their functional state. Functional fragments of ECM macromolecules are a viable answer to this challenge, as demonstrated by the RGD-based engineered scaffolds, where the tri-peptide, Arg-Gly-Asp (RGD), represents the minimal functional unit of fibronectin and related ECM. Laminins (Ln) are main components of epithelial tissues, since they enter into the composition of basement membranes. Application of Ln to epithelial tissue engineering would be desirable, since they could help mimic ideal functional conditions for both lining and glandular epithelial tissues. However, functional fragments of Ln that cou! ld be used in artificial settings have not been characterized in detail. In this paper, we describe the production and application of the recombinant LG4 (rLG4) fragment of laminin-332 (Ln-332), and show that it mimics three fundamental functional properties of Ln-332: integrin-mediated cell adhesion, spreading, and migration. Adhesive structures formed by cells on rLG4 closely resemble those formed on Ln-332, as judged by microscopy-based analyses of their molecular composition. As on Ln-332, focal adhesion kinase (FAK) is phosphorylated in cells adhering to rLG4, and colocalized with other focal adhesion components. We conclude that rLG4 could be a useful substitute to recapitulate, in vitro, the tissue scaffolding properties of Ln-332. PMID: 20347131 [PubMed - as supplied by publisher] | | |
| Design and synthesis of a potent peptide containing both specific and non-specific cell-adhesion motifs.
March 30, 2010 at 6:31 AM
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| | Design and synthesis of a potent peptide containing both specific and non-specific cell-adhesion motifs. Biomaterials. 2010 Mar 24; Authors: Lai Y, Xie C, Zhang Z, Lu W, Ding J This article reports a potent chemical to promote cell adhesion on a substrate by combination of both moieties for specific and non-specific adhesion. The cyclic (-RGDfK-) (R: arginine, G: glycine, D: aspartic acid, f: d-phenylalanine, K: lysine) is employed to trigger specific cell adhesion, and a linear tripeptide KKK is introduced to enhance early non-specific cell adhesion. A series of cyclic and linear peptides with different charges were synthesized and then functionalized with thiol end-group. All the peptides were immobilized on gold layers, which were later passivated by bovine serum albumin. The coverage of NIH/3T3 fibroblast cells on the substrate modified by the linker containing both cyclic (-RGDfK-) and linear KKK is, surprisingly, significantly better than the summation using one of them, which reveals the strong cooperativity of specific and non-specific cell adhesions. The resultant cell adhesion on the substrates modified by appropriate linkers w! as much better than on tissue-culture plates. The cooperativity principle and the design strategy of the combined linker might be helpful for fundamental research of cell-material or cell-extracellular matrix interactions, and for modification of new biomaterials in regenerative medicine and targeted drug delivery. PMID: 20346502 [PubMed - as supplied by publisher] | | |
| A defined long-term in vitro tissue engineered model of neuromuscular junctions.
March 30, 2010 at 6:31 AM
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| | A defined long-term in vitro tissue engineered model of neuromuscular junctions. Biomaterials. 2010 Mar 24; Authors: Das M, Rumsey JW, Bhargava N, Stancescu M, Hickman JJ Neuromuscular junction (NMJ) formation, occurring between motoneurons and skeletal muscle, is a complex multistep process involving a variety of signaling molecules and pathways. In vitro motoneuron-muscle co-cultures are powerful tools to study the role of different growth factors, hormones and cellular structures involved in NMJ formation. In this study, a serum-free culture system utilizing defined temporal growth factor application and a non-biological substrate resulted in the formation of robust NMJs. The system resulted in long-term survival of the co-culture and selective expression of neonatal myosin heavy chain, a marker of myotube maturation. NMJ formation was verified by colocalization of dense clusters of acetylcholine receptors visualized using alpha-bungarotoxin and synaptophysin containing vesicles present in motoneuron axonal terminals. This model will find applications in basic NMJ research and tissue engineering applications such as bio-hybrid d! evice development for limb prosthesis and regenerative medicine as well as for high-throughput drug and toxin screening applications. PMID: 20346499 [PubMed - as supplied by publisher] | | |
| The influence of discoidin domain receptor 2 on the persistence length of collagen type I fibers.
March 30, 2010 at 6:31 AM
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| | The influence of discoidin domain receptor 2 on the persistence length of collagen type I fibers. Biomaterials. 2010 Mar 24; Authors: Sivakumar L, Agarwal G Collagen fibers in the vertebrate tissue are responsible for its tensile strength. A disruption in the morphological or mechanical properties of collagen fibers is bound to impact tensile strength and contractility of tissues and affect several cellular processes. We had recently established that binding of discoidin domain receptor (DDR2) with collagen type I results in disruption of the native structure and morphology of collagen fibers. In this study we investigate if DDR2 affects the mechanical properties of collagen fibers. We used an analytical approach to determine the persistence length (P(L)) of collagen fibers from transmission electron microscope images of immobilized collagen. Fluctuations in the curvature of collagen fibers formed in-vitro (with or without recombinant DDR2) were analyzed to ascertain their P(L). The P(L) values and fiber-diameter measurements were utilized to estimate Young's Modulus (E) of collagen fibers. Our results show that DDR2 ! significantly reduced P(L) and E of collagen fibers. We further found that P(L) for native collagen fibers increases as a function of collagen concentration with little dependence on fiber diameter. These results signify a physiological role of DDR2 in modulating extracellular matrix stiffness, which may be of relevance for tissue engineering and medical implants especially in diseases where DDR2 is upregulated. PMID: 20346496 [PubMed - as supplied by publisher] | | |
| Shaping the micromechanical behavior of multi-phase composites for bone tissue engineering.
March 30, 2010 at 6:31 AM
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| | Shaping the micromechanical behavior of multi-phase composites for bone tissue engineering. Acta Biomater. 2010 Mar 23; Authors: Ranganathan SI, Yoon DM, Henslee A, Nair MB, Smid C, Kasper KF, Tasciotti E, Mikos AG, Decuzzi P, Ferrari M Mechanical stiffness is a fundamental parameter in the rational design of composites for bone tissue engineering in that it affects both the mechanical stability and the osteo-regeneration process at the fracture site. A mathematical model is presented for predicting the effective Young's (E) and shear (G) moduli of a multi-phase biocomposite as a function of the geometry, material properties and volume concentration of each individual phase. It is demonstrated that the shape of the reinforcing particles may dramatically affect the mechanical stiffness: E and G can be maximized by employing particles with large geometrical anisotropy, such as thin platelet-like or long fibrillar-like particles. For a porous poly(propylene fumarate) (PPF) (60% porosity) scaffold reinforced with silicon particles (10% volume concentration), the Young's (shear) modulus could be increased more than 10 times by just using thin platelet-like as opposed to classical spherical particles, ! achieving an effective modulus of E approximately 8 GPa (G approximately 3.5 GPa). The mathematical model proposed provides results in good agreement with several experimental test cases and could help in identifying the proper formulation of bone scaffolds, reducing the development time and guiding the experimental testing. PMID: 20346422 [PubMed - as supplied by publisher] | | |
| Augmentation of bone defect healing using a new biocomposite scaffold: An in vivo study in sheep.
March 30, 2010 at 6:31 AM
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| | Augmentation of bone defect healing using a new biocomposite scaffold: An in vivo study in sheep. Acta Biomater. 2010 Mar 26; Authors: van der Pol U, Mathieu L, Zeiter S, Bourban PE, Zambelli PY, Pearce SG, Bouré L, Pioletti DP Previous studies support resorbable biocomposites made of poly(l-lactic acid) (PLA) and beta-tricalcium phosphate (TCP) produced by supercritical gas foaming as a suitable scaffold for tissue engineering. The present study was undertaken to demonstrate the biocompatibility and osteoconductive properties of such a scaffold in a large animal cancellous bone model. The biocomposite (PLA/TCP) was compared with a currently used beta-TCP bone substitute (ChronOS, Dr. Robert Mathys Foundation), representing a positive control, and empty defects, representing a negative control. Ten defects were created in sheep cancellous bone, three in the distal femur and two in the proximal tibia of each hind limb, with diameters of 5mm and depths of 15mm. New bone in-growth (osteoconductivity) and biocompatibility were evaluated using microcomputed tomography and histology at 2, 4 and 12months after surgery. The in vivo study was validated by the positive control (good bone formation! with ChronOS) and the negative control (no healing with the empty defect). A major finding of this study was incorporation of the biocomposite in bone after 12months. Bone in-growth was observed in the biocomposite scaffold, including its central part. Despite initial fibrous tissue formation observed at 2 and 4months, but not at 12months, this initial fibrous tissue does not preclude long-term application of the biocomposite, as demonstrated by its osteointegration after 12months, as well as the absence of chronic or long-term inflammation at this time point. PMID: 20346421 [PubMed - as supplied by publisher] | | |
| Proteome analysis of human Wharton's jelly cells during in vitro expansion.
March 30, 2010 at 6:31 AM
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| | Proteome analysis of human Wharton's jelly cells during in vitro expansion. Proteome Sci. 2010 Mar 26;8(1):18 Authors: Angelucci S, Marchisio M, Di Giuseppe F, Pierdomenico L, Sulpizio M, Eleuterio E, Lanuti P, Sabatino G, Miscia S, Di Ilio C ABSTRACT: BACKGROUND: The human umbilical cord contains mucoid connective tissue and fibroblast-like cells. These cells, named Wharton's jelly cells, (WJCs) display properties similar to mesenchymal stem cells representing, therefore a rich source of primitive cells to be potentially used in regenerative medicine. RESULTS: To better understand their self-renewal and potential in vitro expansion capacity, a reference 2D map as proteomic data set was constructed. 158 unique proteins were identified. More than 30% of these proteins belongs to cytoskeleton compartment. We have also found that several proteins including Shootin1, Adenilate kinase 5 and Plasminogen activator-inhibitor type-2 are no more expressed after the second passage of in vitro replication. This indicates that the proliferative potency of these cells is reduced after the initial stage of in vitro growing. On the other hand, at the end of cellular culturing, new synthetized proteins, including Oxido! reductin-1-Lalpha, Aspartyl-tRNA synthetase and Prolyl-4-hydroxylase were identified. It is suggested that these new synthetized proteins are involved in the impairment of cellular surviving during replication and differentiation time. Conclusion: Our work represents an essential step in the knowledge of the molecular properties of WJCs to better understand their possible use in the field of cell therapy and regenerative medicine. PMID: 20346146 [PubMed - as supplied by publisher] | | |
| Segmental bone defects: from cellular and molecular pathways to the development of novel biological treatments.
March 30, 2010 at 6:31 AM
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| | Segmental bone defects: from cellular and molecular pathways to the development of novel biological treatments. J Cell Mol Med. 2010 Mar 25; Authors: Pneumaticos SG, Triantafyllopoulos GK, Basdra EK, Papavassiliou AG ABSTRACT Several conditions in clinical orthopaedic practice can lead to the development of a diaphyseal segmental bone defect, which cannot heal without intervention. Segmental bone defects have been traditionally treated with bone grafting and/or distraction osteogenesis, methods that have many advantages, but also major drawbacks, such as limited availability, risk of disease transmission, prolonged treatment. In order to overcome such limitations, biological treatments have been developed based on specific pathways of bone physiology and healing. Bone tissue engineering is a dynamic field of research, combining osteogenic cells, osteoinductive factors, such as bone morphogenetic proteins, and scaffolds with osteoconductive and osteoinductive attributes, to produce constructs that could be used as bone graft substitutes for the treatment of segmental bone defects. Scaffolds are usually made of ceramic or polymeric biomaterials, or combinations of both in compos! ite materials. The purpose of the present review is to discuss in detail the molecular and cellular basis for the development of bone tissue engineering constructs. PMID: 20345845 [PubMed - as supplied by publisher] | | |
| Isolation and Differentiation of Mesenchymal Stem Cells From Bovine Umbilical Cord Blood.
March 30, 2010 at 6:31 AM
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| | Isolation and Differentiation of Mesenchymal Stem Cells From Bovine Umbilical Cord Blood. Reprod Domest Anim. 2010 Mar 22; Authors: Raoufi M, Tajik P, Dehghan M, Eini F, Barin A Contents Currently, mesenchymal stem cells (MSCs) are used in veterinary clinical applications. Bone marrow and adipose tissue are the most common sources of stem cells derived from adult animals. However, cord blood which is collected non-invasively is an alternative source of stem cells other than bone marrow and adipose tissue. Moreover, high availability and lower immunogenicity of umbilical cord blood (UCB) haematopoietic stem cells compared to other sources of stem cell therapy such as bone marrow have made them a considerable source for cell therapy, but MSCs is not highly available in cord blood and their immunogenicity is poorly understood. In this study, the cells with spindle morphology from 7 of 9 bovine UCB samples were isolated and cultured. These mesenchymal stromal cells were successfully differentiated to osteocytes, chondrocytes and adipocytes. In addition, Oct-4 and SH3 were determined by RT-PCR assay. It is the first report of isolation, cultur! e, characterization and differentiation of bovine umbilical stem cells. PMID: 20345587 [PubMed - as supplied by publisher] | | |
| Hypoxia responsive mesenchymal stem cells derived from human umbilical cord blood are effective for bone repair.
March 30, 2010 at 6:31 AM
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| | Hypoxia responsive mesenchymal stem cells derived from human umbilical cord blood are effective for bone repair. Stem Cells Dev. 2010 Mar 26; Authors: Nagano M, Kimura K, Yamashita T, Ohneda K, Nozawa D, Hamada H, Yoshikawa H, Ochiai N, Ohneda O Abstract The differentiation of mesenchymal stem cells (MSC) is multipotential and these cells are a most potential cell-type for a variety of cell therapies. Currently, MSC derived from umbilical cord blood are generally isolated by their plastic adherence without using specific cell surface markers and examined for their osteogenic, adipogenic and chondrogenic differentiation properties retrospectively. Here, we report that MSC can be separated into two subpopulations based on aldehyde dehydrogenase (ALDH) activity. MSC with a high ALDH activity (Alde-High) are more highly proliferating than those with a low ALDH activity (Alde-Low). Moreover, in vitro culture, Alde-High MSC have a greater ability to differentiate than Alde-Low MSC. In fact, early repair and rapid bony substitution took place following the transplantation of Alde-High MSC, rather than Alde-Low MSC, into fractured mouse femurs. Alde-High MSC were also more responsive to hypoxia than Alde-Low MSC,! with the upregulation of Flt-1, CXCR4 and Angiopoietin-2. Thus, MSC with a high ALDH activity might serve as an effective therapeutic tool for healing fractures within a short period of time. PMID: 20345248 [PubMed - as supplied by publisher] | | |
| Macroporous Hydrogels Upregulate Osteogenic Signal Expression and Promote Bone Regeneration.
March 30, 2010 at 6:31 AM
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| | Macroporous Hydrogels Upregulate Osteogenic Signal Expression and Promote Bone Regeneration. Biomacromolecules. 2010 Mar 26; Authors: Betz MW, Yeatts AB, Richbourg WJ, Caccamese JF, Coletti DP, Falco EE, Fisher JP The objective of this work was to investigate the effects of macroporous hydrogel architecture on the osteogenic signal expression and differentiation of human mesenchymal stem cells (hMSCs). In particular, we have proposed a tissue engineering approach for orbital bone repair based on a cyclic acetal biomaterial formed from 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD) and poly(ethylene glycol) diacrylate (PEGDA). The EHD monomer and PEGDA polymer may be fabricated into macroporous EH-PEG hydrogels by radical polymerization and subsequent porogen leaching, a novel technique for hydrophilic gels. We hypothesized that EH-PEG hydrogel macroporosity facilitates intercellular signaling among hMSCs. To investigate this phenomenon, hMSCs were loaded into EH-PEG hydrogels with varying pore size and porosity. The viability of hMSCs, the expression of bone morphogenetic protein-2 (BMP-2), BMP receptor type 1A, and BMP receptor type 2 b! y hMSCs, and the differentiation of hMSCs were then assessed. Results demonstrate that macroporous EH-PEG hydrogels support hMSCs and that this macroporous environment promotes a dramatic increase in BMP-2 expression by hMSCs. This upregulation of BMP-2 expression is associated by a more rapid hMSC differentiation, as measured by alkaline phosphatase expression. Altering hMSC interactions with the EH-PEG hydrogel surface, by the addition of fibronectin, did not appear to augment BMP-2 expression. We therefore speculate that EH-PEG hydrogel macroporosity facilitates autocrine and paracrine signaling by localizing endogenously expressed factors within the hydrogel's pores and thus promotes hMSC osteoblastic differentiation and bone regeneration. PMID: 20345129 [PubMed - as supplied by publisher] | | |
| Distinct hematopoietic stem cell subtypes are differentially regulated by TGF-beta1.
March 30, 2010 at 6:31 AM
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| | Distinct hematopoietic stem cell subtypes are differentially regulated by TGF-beta1. Cell Stem Cell. 2010 Mar 5;6(3):265-78 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. PMID: 20207229 [PubMed - indexed for MEDLINE] | | |
| Translational systems biology of inflammation and healing.
March 30, 2010 at 6:31 AM
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| | Translational systems biology of inflammation and healing. Wound Repair Regen. 2010 Jan-Feb;18(1):3-7 Authors: Vodovotz Y Personalized medicine is a major goal for the future of healthcare, and we suggest that computational simulations are necessary in order to achieve it. Inflammatory diseases, both acute and chronic, represent an area in which personalized medicine is especially needed, given the high level of individual variability that characterizes these diseases. We have created such simulations, and have used them to gain basic insights into the inflammatory response under baseline, gene-knockout, and drug-treated experimental animals; for in silico experiments and clinical trials in sepsis, trauma, and wound healing; and to create patient-specific simulations in polytrauma, traumatic brain injury, and vocal fold inflammation. Since they include both circulating and tissue-level inflammatory mediators, these simulations transcend typical cytokine networks by associating inflammatory processes with tissue/organ damage via tissue damage/dysfunction. We suggest that computational! simulations are the cornerstone of Translational Systems Biology approaches for inflammatory diseases. PMID: 20082674 [PubMed - indexed for MEDLINE] | | |
| Biomimetic Ca-P coatings incorporating bisphosphonates produced on starch-based degradable biomaterials.
March 30, 2010 at 6:31 AM
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| | Biomimetic Ca-P coatings incorporating bisphosphonates produced on starch-based degradable biomaterials. J Biomed Mater Res B Appl Biomater. 2010 Jan;92(1):55-67 Authors: Oliveira AL, Pedro AJ, Arroyo CS, Mano JF, Rodriguez G, San Roman J, Reis RL In this study, sodium clodronate, a well-known therapeutic agent from the family of bisphosphonates (BPs), is incorporated in a biomimetic calcium phosphate (CaP) coating, previously formed on the surface of a starch-based biomaterial by a sodium silicate methodology, as a strategy to develop a site-specific drug delivery system for bone tissue regeneration applications. The effects on the resulting CaP coatings were evaluated in terms of morphology, chemistry, and structure. The dissolution of Ca and P from the coating and the release profiles of sodium clodronate was also assessed. As a preliminary approach, this first study also aimed at evaluating the effects of this BP on the viability of a human osteoblastic cell line since there is still little information available on the interaction between BPs and this type of cells. Sodium clodronate was successfully incorporated, at different doses, in the structure of a biomimetic CaP layer previously formed by a sodi! um silicate process. This type of BPs had a stimulatory effect on osteoblastic activity, particularly at the specific concentration of 0.32 mg/mL. It is foreseen that these coatings can, for instances, be produced on the surface of degradable polymers and then used for regulating the equilibrium on osteoblastic/osteoclastic activity, leading to a controlled regenerative effect at the interface between the biomaterial and bone. PMID: 19701915 [PubMed - indexed for MEDLINE] | | | | 
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