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| Multipotent mesenchymal stem cell grafting to treat cutaneous radiation syndrome: development of a new minipig model.
July 6, 2010 at 9:06 AM
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| | Multipotent mesenchymal stem cell grafting to treat cutaneous radiation syndrome: development of a new minipig model. Exp Hematol. 2010 Jun 25; Authors: Agay D, Scherthan H, Forcheron F, Grenier N, Hérodin F, Meineke V, Drouet M OBJECTIVES: Cutaneous radiation syndrome (CRS) is the delayed consequence of localized skin exposure to high doses of ionizing radiation (IR). Recent grafting of three IR-burned patients has suggested the benefit of local bone marrow mesenchymal stem cell (MSC) injection in favour of wound healing and pain control. Here, we have developed a new minipig model of severe CRS to study underlying mechanisms of this cell therapy approach. MATERIALS AND METHODS: Göttingen minipigs were locally irradiated using a (60)Co gamma source as follows: ungrafted 50 and 60 Gy (n=4); grafted 50 and 60 Gy (n=3). Bone marrow MSCs were cultured in MEM with 10% fetal calf serum and basic fibroblast growth factor (2ng.mL(-1)). Autologous MSCs were intradermally injected twice or three times from days 27 to 96 (range 99-128.5x10(6) MSCs per injection). RESULTS: All animals exhibited a clinical evolution similar to human after a latency phase of several weeks: early erythema, hair loss, dry/moist desquamation followed by necrosis during 81 - 222 days post IR. Skin damage in higher exposed animals appeared slightly earlier. Immuno-histology revealed severe skin damage in all animals and rhabdomyolysis in the muscle tissue below the entry area, with the latter being more severe in controls. In grafted animals, the MSCs led to local accumulation of lymphocytes at the dermis/subcutis border and improved vascularization. CONCLUSION: This study establishes a new minipig model that is close to human and allows the development of stem cell therapy strategies that may be applied in treatment of human radiation burns. PMID: 20600578 [PubMed - as supplied by publisher] | | |
| Oxygen and oxygenation in stem-cell therapy for myocardial infarction.
July 6, 2010 at 9:06 AM
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| | Oxygen and oxygenation in stem-cell therapy for myocardial infarction. Life Sci. 2010 Jun 28; Authors: Khan M, Kwiatkowski P, Rivera BK, Kuppusamy P Myocardial infarction (MI) is caused by deprivation of oxygen and nutrients to the cardiac tissue due to blockade of coronary artery. It is a major contributor to chronic heart disease, a leading cause of mortality in the modern world. Oxygen is required to meet the constant energy demands for heart contractility, and also plays an important role in the regulation of heart function. However, reoxygenation of the ischemic myocardium upon restoration of blood flow may lead to further injury. Controlled oxygen delivery during reperfusion has been advocated to prevent this consequence. Monitoring the myocardial oxygen concentration would play a vital role in understanding the pathological changes in the ischemic heart following myocardial infarction. During the last two decades, several new techniques have become available to monitor myocardial oxygen concentration in vivo. Electron paramagnetic resonance (EPR) oximetry would appear to be the most promising and reliable of these techniques. EPR utilizes crystalline probes which yield a single sharp line, the width of which is highly sensitive to oxygen tension. Decreased oxygen tension results in a sharpening of the EPR spectrum, while an increase results in widening. In our recent studies, we have used EPR oximetry as a valuable tool to monitor myocardial oxygenation for several applications like ischemia-reperfusion injury, stem-cell therapy and hyperbaric oxygen therapy. The results obtained from these studies have demonstrated the importance of tissue oxygen in the application of stem cell therapy to treat ischemic heart tissues. These results have been summarized in this review article. PMID: 20600148 [PubMed - as supplied by publisher] | | |
| Gene therapy for ischemic heart disease.
July 6, 2010 at 9:06 AM
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| | Gene therapy for ischemic heart disease. J Mol Cell Cardiol. 2010 Jul 2; Authors: Lavu M, Gundewar S, Lefer DJ Current pharmacologic therapy for ischemic heart disease suffers multiple limitations such as compliance issues and side effects of medications. Revascularization procedures often end with need for repeat procedures. Patients remain symptomatic despite maximal medical therapy. Gene therapy offers an attractive alternative to current pharmacologic therapies and may be beneficial in refractory disease. Gene therapy with isoforms of growth factors such as VEGF, FGF and HGF induces angiogenesis, decreases apoptosis and leads to protection in the ischemic heart. Stem cell therapy augmented with gene therapy used for myogenesis has proven to be beneficial in numerous animal models of myocardial ischemia. Gene therapy coding for antioxidants, eNOS, HSP, mitogen-activated protein kinase and numerous other anti apoptotic proteins have demonstrated significant cardioprotection in animal models. Clinical trials have demonstrated safety in humans apart from symptomatic and objective improvements in cardiac function. Current research efforts are aimed at refining various gene transfection techniques and regulation of gene expression in vivo in the heart and circulation to improve clinical outcomes in patients that suffer from ischemic heart disease. In this review article we will attempt to summarize the current state of both preclinical and clinical studies of gene therapy to combat myocardial ischemic disease. PMID: 20600100 [PubMed - as supplied by publisher] | | |
| Carboxymethylchitosan/Poly(amidoamine) Dendrimer Nanoparticles in Central Nervous Systems-Regenerative Medicine: Effects on Neuron/Glial Cell Viability and Internalization Efficiency.
July 6, 2010 at 8:26 AM
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| | Carboxymethylchitosan/Poly(amidoamine) Dendrimer Nanoparticles in Central Nervous Systems-Regenerative Medicine: Effects on Neuron/Glial Cell Viability and Internalization Efficiency. Macromol Biosci. 2010 Jul 2; Authors: Salgado AJ, Oliveira JM, Pirraco RP, Pereira VH, Fraga JS, Marques AP, Neves NM, Mano JF, Reis RL, Sousa N The applicability of CMCht/PAMAM dendrimer nanoparticles for CNS applications was investigated. AFM and TEM observations revealed that the nanoparticles possessed a nanosphere-like shape with a size from 22.0 to 30.7 nm. The nanoparticles could be bound to fluorescent-probe FITC for tracing purposes. Post-natal hippocampal neurons and cortical glial cells were both able to internalize the FITC-labeled CMCht/PAMAM dendrimer nanoparticles with high efficiency. The percentage of positive cells internalizing the nanoparticles varied, reaching a peak after 48 h of incubation. Further experiments for periods up to 7 d revealed that the periodical addition of FITC-labelled CMCht/PAMAM dendrimer nanoparticles was needed to maintain the overall percentage of cells internalizing them. Finally, it was also observed that cell viability was not significantly affected by the incubation of dendrimer nanoparticles. PMID: 20602413 [PubMed - as supplied by publisher] | | |
| Development of Cell-processing Systems for Human Stem Cells (Neural Stem Cells, Mesenchymal Stem Cells, and iPS Cells) for Regenerative Medicine.
July 6, 2010 at 8:26 AM
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| | Development of Cell-processing Systems for Human Stem Cells (Neural Stem Cells, Mesenchymal Stem Cells, and iPS Cells) for Regenerative Medicine. Keio J Med. 2010 Jun;59(2):35-45 Authors: Kanemura Y Regenerative medicine using human stem cells is one of the newest and most promising fields for treating various intractable diseases and damaged organs. For clinical applications, choosing which human stem cells to use, i.e. according to tissue of origin and progenitor type, is a critical issue. Neural stem/progenitor cells (NSPCs) hold promise for treating various neurological diseases. We have shown that the transporter protein ABCB1 is predominantly expressed in immature human fetal NSPCs, and thus could be used as a phenotypic marker to investigate and monitor NSPCs in culture. We describe our proposed model for the in vitro proliferative process of aggregated human NSPCs and show that neurosphere enlargement and NSPC proliferation are mutually reinforcing. We have established that human neurospheres contain a heterogeneous cell population, knowledge that will contribute to the development of human neurospheres with desirable characteristics for clinical applications. Furthermore, decidua-derived mesenchymal cells (DMCs), which we isolated from human placenta, have unique properties as mesenchymal stem cells. They also generate a pericellular matrix (PCM-DM) that supports the growth and pluripotency of human embryonic stem cells and induced pluripotent stem cells (hiPS) cells. The newly developed re-programming techniques for generating hiPS cells should greatly contribute to cell therapies using human pluripotent stem cells, including those derived from DMCs. Our DMC-derived hiPS cells are a promising candidate source of allogeneic hiPS cells for clinical applications. We hope our findings will contribute to the development of cell-culture systems for generating human allogeneic stem cells for clinical use in regenerative medicine. PMID: 20601839 [PubMed - in process] | | |
| The anti-calcification potential of a silsesquioxane nanocomposite polymer under in vitro conditions: Potential material for synthetic leaflet heart valve.
July 6, 2010 at 8:26 AM
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| | The anti-calcification potential of a silsesquioxane nanocomposite polymer under in vitro conditions: Potential material for synthetic leaflet heart valve. Acta Biomater. 2010 Jun 18; Authors: Ghanbari H, Kidane AG, Burriesci G, Ramesh B, Darbyshire A, Seifalian AM Calcification currently represents a major cause of failure of biological tissue heart valves. It is a complex phenomenon influenced by a number of biochemical and mechanical factors. Recent advances in material science offer new polymers with improved properties, potentially suitable for synthetic leaflets heart valves manufacturing. In this study, the calcification-resistance efficacy and mechanical and surface properties of a new nanocomposite polymeric material (polyhedral oligomeric silsesquioxane-poly(carbonate-urea)urethane; POSS-PCU) which has been developed by our group are assessed by means of in vitro testing. In particular, thin sheets of nanocomposite, glutaraldehyde-fixed bovine pericardium (BP) and polyurethane (PU) were exposed to a calcium solution into a specially designed in vitro accelerated physiological pulsatile pressure system for a period of 31days and a total of 4x10(7) cycles. The samples were investigated for signs of calcification after exposure to calcium solution by means of X-ray, microscopic and chemical inspections. Mechanical and surface properties were also studied using stress-strain behaviour and surface morphology and hydrophobicity. Comparison shows that, in the experimental conditions, the level of calcification for the nanocomposite is considerably lower than for the fixed BP (p=0.008) and PU samples (p=0.015). Also, mechanical properties were unchanged in POSS-PCU, while there was a significant deterioration in PU samples (p<0.05). Hydrophobicity was significantly reduced in both the POSS-PCU and PU samples (p<0.0001). However, the POSS-PCU nanocomposite remained more hydrophobic than the PU sample (p<0.0001). Less platelet adhered to the POSS-PCU compared to the PU (p<0.0001). These results indicate that the use of this nanocomposite in synthetic leaflets heart valves may lead to potential advantages in terms of long-term performances and durability. PMID: 20601232 [PubMed - as supplied by publisher] | | |
| In vivo short-term and long-term host reaction to starch-based scaffolds.
July 6, 2010 at 8:26 AM
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| | In vivo short-term and long-term host reaction to starch-based scaffolds. Acta Biomater. 2010 Jun 23; Authors: Santos TC, Marques AP, Höring B, Martins AR, Tuzlakoglu K, Castro AG, van Griensven M, Reis RL The implantation of biomaterials may elicit a host response to this foreign body, and the magnitude of that reaction depends on the host and on the implanted material. The aim of this study was to compare the inflammatory response induced by the implantation of starch-based (SPCL) scaffolds in two implantation rat models: subcutaneous (SC) and intramuscular (IM). Moreover, two methodologies, wet spinning (WS) and fibre-bonding (FB), were used to prepare the scaffolds. The short-term inflammatory/immune host reaction was assessed by SC and IM implantations in rats after 1 and 2weeks, and the long-term host response was addressed after 8 and 12weeks of SC implantation of both types of SPCL scaffolds in rats. After each time period, the scaffolds, surrounding tissue and nearby lymph nodes were explanted, and used for histological analysis and molecular biology evaluation. The results showed that SPCL-WS scaffolds seem to induce a slight lower inflammatory/immune reaction in both types of implantation models. Nonetheless, comparing the two models, the IM implantation resulted in a slightly higher inflammatory response than the SC implantation with early activation of the lymph nodes. The overall data suggests a good integration of the materials in the host, independently of the tissue location with a normal progress of the reaction for all the conditions. PMID: 20601228 [PubMed - as supplied by publisher] | | |
| Can controlled cellular reprogramming be achieved using microRNAs?
July 6, 2010 at 8:26 AM
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| | Can controlled cellular reprogramming be achieved using microRNAs? Ageing Res Rev. 2010 Jun 20; Authors: Sun X, Fu X, Han W, Zhao Y, Liu H Since a technique was reported for generating induced pluripotent stem cells (iPSCs), various groups worldwide have reprogrammed human and mouse somatic cells into iPSCs using a range of techniques and pluripotency genes. Progress in iPSC research has opened up a novel avenue in autologous regenerative medicine, whereby patient-specific pluripotent cells could potentially be derived from adult somatic cells. However, several limitations currently prohibit their use in clinical settings, including the viral DNA delivery system and the exogenous overexpression of pluripotency genes. New strategies are therefore needed to ensure the safe and efficient production of iPSCs, and to guide their differentiation into the desired lineages required to repair damaged tissue and treat disease. Here, we present an overview of recent research into cellular reprogramming. We focus on the feasibility of microRNA-based strategies for reprogramming somatic cells into pluripotent stem cells, thus obviating the need to introduce viruses or DNA into donor cells, and therefore ameliorating the risks associated with reprogramming techniques. In light of the critical roles of microRNAs in maintaining the pluripotent state and in regulating cell-lineage specification and epigenetic modifications of chromatin, we also discuss the potential role of microRNAs as candidates for controlled cellular reprogramming and induction of cell fate conversion beyond lineages without reversion to a pluripotent state. Further research into the microRNAs involved in iPSC reprogramming and their potential roles in controlled cellular reprogramming will add another dimension to our understanding of the molecular mechanisms involved in cellular reprogramming. PMID: 20601195 [PubMed - as supplied by publisher] | | |
| Comprehension of ECM-Cell dynamics; A prerequisite for tissue regeneration.
July 6, 2010 at 8:26 AM
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| | Comprehension of ECM-Cell dynamics; A prerequisite for tissue regeneration. Biotechnol Adv. 2010 Jun 18; Authors: Dutta RC, Dutta AK Tissue regeneration and cell therapy has an enormous potential in healthcare through the creation of artificial human tissues and organs. Possibility of producing functional replica of tissues and organs can offer a common, solitary solution for various kinds of inflictions. It can also provide an ultimate test model for drug discovery. There exists convincing evidence that if cells are cultured in extra cellular matrix (ECM) mimicking 3D scaffolds infused with tissue specific biochemical cues they grow and differentiate to express functionality. However, comprehensive understanding of ECM and its dynamic relation with the growing cells is vital for creating functional tissue models ex vivo. Different medical and non-medical groups all over the world are working towards achieving affordable, user friendly and technically viable solutions for improving our understanding of Cell-ECM dynamics for tissue engineering (TE). Successful TE, an ambitious goal that includes tissue neogenesis in vitro and functional tissue mending (regenerative medicine) in vivo, however involves innumerable challenges. Present review discusses some of the major technical hurdles that hinder the pace of progress in tissue regeneration/engineering (TE). PMID: 20600786 [PubMed - as supplied by publisher] | | |
| The use of transcranial magnetic stimulation in cognitive neuroscience: A new synthesis of methodological issues.
July 6, 2010 at 8:26 AM
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| | The use of transcranial magnetic stimulation in cognitive neuroscience: A new synthesis of methodological issues. Neurosci Biobehav Rev. 2010 Jun 25; Authors: Sandrini M, Umiltà C, Rusconi E Transcranial magnetic stimulation (TMS) has become a mainstay of cognitive neuroscience, thus facing new challenges due to its widespread application on behaviorally silent areas. In this review we will summarize the main technical and methodological considerations that are necessary when using TMS in cognitive neuroscience, based on a corpus of studies and technical improvements that has become available in most recent years. Although TMS has been applied only relatively recently on a large scale to the study of higher functions, a range of protocols that elucidate how this technique can be used to investigate a variety of issues is already available, such as single pulse, paired pulse, dual-site, repetitive and theta burst TMS. Finally, we will touch on recent promising approaches that provide powerful new insights about causal interactions among brain regions (i.e., TMS with other neuroimaging techniques) and will enable researchers to enhance the functional resolution of TMS (i.e., state-dependent TMS). We will end by briefly summarizing and discussing the implications of the newest safety guidelines. PMID: 20599555 [PubMed - as supplied by publisher] | | |
| MALDI-TOF mass array analysis of RASSF1A and SERPINB5 methylation patterns in human placenta and plasma.
July 6, 2010 at 8:26 AM
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| | MALDI-TOF mass array analysis of RASSF1A and SERPINB5 methylation patterns in human placenta and plasma. Biol Reprod. 2010 Apr;82(4):745-50 Authors: Bellido ML, Radpour R, Lapaire O, De Bie I, Hösli I, Bitzer J, Hmadcha A, Zhong XY, Holzgreve W Differences in DNA methylation patterns between placenta and blood cells of pregnant women have been suggested as potential biomarkers for noninvasive prenatal diagnostic strategies, including for common obstetrical complications, such as preeclampsia. New findings in epigenetic origins of fetal or placental disorders may improve our ability for optimal management of these conditions. Using a novel high-throughput mass spectrometry on matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass array, we compared the quantitative methylation changes of RASSF1 and SERPINB5 (also known as MASPIN) genes in placenta and plasma samples. We analyzed the methylation status of a total of 3569 CpG dinucleotides on these two genes in 83 different samples: 50 plasma samples (20 from pregnant women and 30 from nonpregnant women) and 33 placenta tissue samples (25 from normal pregnancies and eight from preeclamptic pregnancies). The aim of this study was to assess the utility of epigenetic changes as biomarkers for noninvasive prenatal diagnostic procedures. Using a two-way hierarchical cluster analysis, significantly different methylation levels of the RASSF1 gene were found between placenta (normal and preeclamptic) and plasma samples of pregnant women. Although the SERPINB5 gene was hypomethylated in placenta DNA more than in plasma DNA, it did not demonstrate significant differences between studied groups. The MALDI-TOF mass spectrometry analysis of placenta and plasma DNA methylation patterns may serve as a tool for the study of gender-independent biomarkers in noninvasive prenatal diagnosis. PMID: 20075396 [PubMed - indexed for MEDLINE] | | |
| Recombinant Spider Silk Proteins for Applications in Biomaterials.
July 6, 2010 at 6:50 AM
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| | Recombinant Spider Silk Proteins for Applications in Biomaterials. Macromol Biosci. 2010 Jul 5; Authors: Spiess K, Lammel A, Scheibel T Due to their extraordinary mechanical and biochemical properties, silks have long been in focus of research. In vivo, fibers are formed from silk proteins, in vitro, however, a variety of materials can be produced in addition to fibers including capsules, particles, films, foams, and gels. The versatility of silk proteins, along with their biocompatibility, biodegradability, and potential for processing in aqueous solution under ambient conditions make silk-based materials good candidates for biomedical applications such as drug delivery systems and scaffolds for tissue engineering. Here, we summarize recent progress in research employing recombinantly produced engineered spider silk proteins with a focus on the fundamentals of silk protein processing. We highlight recombinant spider silk films and particles as morphologies that represent model systems with adjustable material properties controlled by process parameters. PMID: 20602494 [PubMed - as supplied by publisher] | | |
| Fat grafting to the breast and adipose-derived stem cells: recent scientific consensus and controversy.
July 6, 2010 at 6:50 AM
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| | Fat grafting to the breast and adipose-derived stem cells: recent scientific consensus and controversy. Aesthet Surg J. 2010 May 1;30(3):381-7 Authors: Mizuno H, Hyakusoku H Recent technical advances in fat grafting and the development of surgical devices such as liposuction cannulae have made fat grafting a relatively safe and effective procedure. However, new guidelines issued by the American Society of Plastic Surgeons in 2009 announced that fat grafting to the breast is not a strongly recommended procedure, as there are limited scientific data on the safety and efficacy of this particular type of fat transfer. Recent progress by several groups has revealed that multipotent adult stem cells are present in human adipose tissue. This cell population, termed adipose-derived stem cells (ADSC), represents a promising approach to future cell-based therapies, such as tissue engineering and regeneration. In fact, several reports have shown that ADSC play a pivotal role in graft survival through both adipogenesis and angiogenesis. Although tissue augmentation by fat grafting does have several advantages in that it is a noninvasive procedure and results in minimal scarring, it is essential that such a procedure be supported by evidence-based medicine and that further basic scientific and clinical research is conducted to ensure that fat grafting is a safe and effective procedure. PMID: 20601560 [PubMed - in process] | | |
| Bio-functionalization of Materials for Implants Using Engineered Peptides.
July 6, 2010 at 6:50 AM
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| | Bio-functionalization of Materials for Implants Using Engineered Peptides. Acta Biomater. 2010 Jul 2; Authors: Khatayevich D, Gungormus M, Yazici H, So C, Cetinel S, Ma H, Jen A, Tamerler C, Sarikaya M Uncontrolled interactions between synthetic materials and human body are a major concern in implants and tissue engineering. The most successful approaches to circumvent this issue involve the modification of the implant or scaffold surfaces with various functional molecules, such as anti-fouling polymers or cell growth factors. To date, such techniques have relied on surface immobilization methods that are often applicable only to a limited range of materials and require the presence of specific functional groups, synthetic pathways, or biologically hostile environments. In this study we use peptide motifs that have been selected to bind to gold, platinum, glass and titanium to modify surfaces with Poly(ethylene glycol) anti-fouling polymer and the integrin-binding RGD sequence. The peptides have several advantages over conventional molecular immobilization techniques; they require no biologically hostile environments to bind, are specific to their substrates, and could be adapted to carry various active entities. We successfully imparted cell-resistant properties to gold and platinum surfaces using gold and platinum binding peptides respectively, in conjunction with PEG. We also induced a several-fold increase in the number and spreading of fibroblast cells on glass and titanium surfaces using quartz and titanium binding peptides in conjunction with the integrin ligand RGD. The results presented here indicate that control over the extent of the cell-material interactions can be achieved by relatively simple and biocompatible surface modification procedures using inorganic binding peptides as linker molecules. PMID: 20601249 [PubMed - as supplied by publisher] | | |
| Three-dimensional Nanocomposite Scaffolds Fabricated via Selective Laser Sintering for Bone Tissue Engineering.
July 6, 2010 at 6:50 AM
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| | Three-dimensional Nanocomposite Scaffolds Fabricated via Selective Laser Sintering for Bone Tissue Engineering. Acta Biomater. 2010 Jul 2; Authors: Duan B, Wang M, Zhou WY, Cheung WL, Li ZY, Lu WW Bionanocomposites formed by combining biodegradable polymers and nanosized osteoconductive inorganic solids have been regarded as promising biomimetic systems which possess much improved structural and functional properties for bone tissue regeneration. In this study, three-dimensional nanocomposite scaffolds based on calcium phosphate (Ca-P)/poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) and carbonated hydroxyapatite (CHAp)/poly((L)-lactic acid) (PLLA) nanocomposite microspheres were successfully fabricated using selective laser sintering (SLS), which is one of the rapid prototyping technologies. The sintered scaffolds had controlled material microstructure, totally interconnected porous structure and high porosity. The morphology and mechanical properties of Ca-P/PHBV and CHAp/PLLA nanocomposite scaffolds as well as PHBV and PLLA polymer scaffolds were studied. In vitro biological evaluation showed that SaOS-2 cells had high cell viability and normal morphology and phenotype after 3 day and 7 day culture on all scaffolds. The incorporation of Ca-P nanoparticles significantly improved cell proliferation and alkaline phosphatase (ALP) activity for Ca-P/PHBV scaffolds, whereas CHAp/PLLA nanocomposite scaffolds exhibited a similar level of cell response as compared with PLLA polymer scaffolds. The nanocomposite scaffolds provide biomimetic environment for osteoblastic cell attachment, proliferation and differentiation and have great potential for bone tissue engineering applications. PMID: 20601244 [PubMed - as supplied by publisher] | | |
| Design Principles for Cytokine-Neutralizing Gels: Cross-linking Effects.
July 6, 2010 at 6:50 AM
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| | Design Principles for Cytokine-Neutralizing Gels: Cross-linking Effects. Acta Biomater. 2010 Jul 2; Authors: Sun LT, Bencherif SA, Gilbert TW, Lotze MT, Washburn NR Constructs composed of cytokine-neutralizing antibodies conjugated to high molecular weight hyaluronic acid have been shown to be effective at controlling inflammatory responses in vivo. A critical question in the development of this new class of biomaterial is whether cross-linked conjugates have similar anti-inflammatory effects, which would open up a broad range of tissue engineering applications in which the material would have intrinsic inflammation-controlling function. To test this, high molecular weight hyaluronic acid was conjugated with monoclonal antibodies to the pro-inflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha in two forms of the material: viscous, non-cross-linked polymer-antibody conjugates and cross-linked, elastomeric polymer-antibody conjugates. The cytokine affinities of both constructs were validated using molecular characterization methods, and the biological activities were tested through subcutaneous implantation in Sprague-Dawley rats. In vitro, both forms of these constructs are capable of binding cytokines, but in vivo only the non-cross-linked polymer significantly reduces markers of acute inflammation compared to controls that lack the antibodies. We propose that these materials function by retarding cytokine diffusion, with non-cross-linked polymers being capable of retarding the diffusion of cytokines in the extracellular matrix and preventing engagement with receptors. In contrast, cross-linked materials have long diffusion lengths into the gel compared with those between cells on the surface of the material, which may make them ineffective at sequestering pro-inflammatory cytokines on biologically relevant timescales. These results suggest an important design principle for preparing cytokine-regulating materials based on consideration of transport phenomena. PMID: 20601239 [PubMed - as supplied by publisher] | | |
| Genetic profiling of osteoblast-like cells cultured on a novel bone reconstructive material, consisting of poly-l-lactide, carbon nanotubes and microhydroxyapatite, in the presence of bone morphogenetic protein-2.
July 6, 2010 at 6:50 AM
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| | Genetic profiling of osteoblast-like cells cultured on a novel bone reconstructive material, consisting of poly-l-lactide, carbon nanotubes and microhydroxyapatite, in the presence of bone morphogenetic protein-2. Acta Biomater. 2010 Jun 19; Authors: van der Zande M, Walboomers XF, Brännvall M, Olalde B, Jurado MJ, Alava JI, Jansen JA In bone tissue engineering composite materials have been introduced, combining a degradable polymer matrix with, for instance, carbon nanotubes (CNTs) to improve mechanical properties or with microhydroxyapatite (muHA) to improve osteoconduction. The addition of bone morphogenetic protein-2 (BMP-2) can further improve the biological response to the material. However, the influence of such an elaborate composite formation on osteoprogenitor cells is unknown. To examine this, rat bone marrow (RBM) cells were cultured on porous poly-l-lactic acid and composite scaffolds, with or without added BMP-2. Cell proliferation and differentiation were studied using DNA, alkaline phosphatase and scanning electron microscopic analysis. Further, genetic profiles were examined by microarray investigation. Results showed that the composite scaffold had no significant effect on the proliferation of RBM cells, but indicated a negative effect on cell differentiation. The addition of BMP-2 also had no significant effect on the proliferation of RBM cells, but differentiation towards the osteogenic lineage was confirmed. In the arrays results, the addition of BMP-2 alone led to the expression of genes involved in (minor) inflammation. The composite scaffold, and even more distinctly the combination of the composite scaffold with BMP-2, led to the expression of genes, based on gene ontology, connected to tumorigenesis. Therefore, CNT- and muHA-containing composite materials are not recommended as a bone restorative material. PMID: 20601234 [PubMed - as supplied by publisher] | | |
| Manipulation of the adhesive behaviour of skeletal muscle cells on soft and stiff polyelectrolyte multilayers.
July 6, 2010 at 6:50 AM
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| | Manipulation of the adhesive behaviour of skeletal muscle cells on soft and stiff polyelectrolyte multilayers. Acta Biomater. 2010 Jun 19; Authors: Ren K, Fourel L, Rouvière CG, Albiges-Rizo C, Picart C Polyelectrolyte multilayer coatings have emerged as substrates to control a variety of cell behaviour, including adhesion, proliferation and differentiation. In particular, it is possible to modulate film stiffness by physical or chemical cross-linking. In this study, we evaluate the adhesive behaviour of skeletal muscle cells (C2C12 myoblasts) during the initial steps of spreading on layer-by-layer films of controlled stiffness made of poly(l-lysine) and hyaluronan as model biomaterial surfaces for muscle tissue engineering. We show that integrin clustering, integrin actin cytoskeleton connection and focal adhesion formation for cell spreading can be decoupled by controlling film stiffness. This made it possible to switch the cells morphologically between round and spreading shapes depending on the stiffness of the microenvironment. Although hyaluronan is one of the main components of cross-linked multilayer films, the HA receptor CD44 did not appear to mediate early adhesion as suggested by the use of blocking antibodies. In contrast, integrins were found to play a pivotal role in early adhesion: their activation significantly enhanced C2C12 myoblast spreading on soft films, where they were otherwise round. Integrin clustering was also induced by the softer films and enhanced on the stiffest films. Conversely, the use of soluble inhibitors or blocking antibodies directed against integrins induced a round phenotype on stiff films, where cells were well spread out in control conditions. We show that specific integrins were involved in the adhesion process as blocking beta(3), but not beta(1), integrins inhibited cell adhesion. These soft, stiff films can thus be used to tune the adhesion of C2C12 myoblasts, an early key event in myogenesis, via integrin clustering and subsequent signalling. They may be further used to decorticate the signalling pathways associated with beta(3) integrins. PMID: 20601233 [PubMed - as supplied by publisher] | | |
| A study of vascular smooth muscle cell function under cyclic mechanical loading in a polyurethane scaffold with optimized porosity.
July 6, 2010 at 6:50 AM
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| | A study of vascular smooth muscle cell function under cyclic mechanical loading in a polyurethane scaffold with optimized porosity. Acta Biomater. 2010 Jun 20; Authors: Sharifpoor S, Simmons CA, Labow RS, Santerre JP High porosity and pore interconnectivity are important features of a successful tissue engineering scaffold. The objective of this work was to optimize the pore interconnectivity and to increase the porosity of an elastomeric degradable/polar/hydrophobic/ionic (D-PHI) polyurethane porous scaffold while maintaining its mechanical integrity in order to allow for the transfer of mechanical stimulus to vascular smooth muscle cells (VSMCs) seeded onto the scaffold. The effect of varying porogen (sodium bicarbonate (salt) and polyethylene glycol (PEG)) composition and concentration on the mechanical properties, degree of swelling and porosity of the scaffolds was investigated. It was found that the use of 10wt.% PEG and 65wt.% salt in scaffold fabrication (D-PHI-75T) resulted in micropore (1-5mum) formation, a high porosity (79+/-3%) and mechanical properties (elastic modulus=0.16+/-0.03MPa, elongation-at-yield=31+/-5% and tensile strength=0.04+/-0.01MPa) required to withstand the physiologically relevant mechanical strain experienced by VMSCs in vivo. This study also investigated the influence of cyclic mechanical strain (CMS) on select molecular markers of A10 VSMCs when seeded into the optimized D-PHI scaffold. To study the interaction of A10 cells with the optimized D-PHI-75T scaffold in the presence of uniaxial strain (10%, 1Hz), a CMS bioreactor was designed and constructed. Molecular marker studies showed a statistical increase in DNA mass and calponin expression after 3 and 7days of CMS when compared to static samples, indicating that the translation of mechanical loading from the novel polyurethane elastomeric scaffold onto VSMCs will be important to consider with regard to modulating cell phenotype. PMID: 20601230 [PubMed - as supplied by publisher] | | |
| In vivo short-term and long-term host reaction to starch-based scaffolds.
July 6, 2010 at 6:50 AM
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| | In vivo short-term and long-term host reaction to starch-based scaffolds. Acta Biomater. 2010 Jun 23; Authors: Santos TC, Marques AP, Höring B, Martins AR, Tuzlakoglu K, Castro AG, van Griensven M, Reis RL The implantation of biomaterials may elicit a host response to this foreign body, and the magnitude of that reaction depends on the host and on the implanted material. The aim of this study was to compare the inflammatory response induced by the implantation of starch-based (SPCL) scaffolds in two implantation rat models: subcutaneous (SC) and intramuscular (IM). Moreover, two methodologies, wet spinning (WS) and fibre-bonding (FB), were used to prepare the scaffolds. The short-term inflammatory/immune host reaction was assessed by SC and IM implantations in rats after 1 and 2weeks, and the long-term host response was addressed after 8 and 12weeks of SC implantation of both types of SPCL scaffolds in rats. After each time period, the scaffolds, surrounding tissue and nearby lymph nodes were explanted, and used for histological analysis and molecular biology evaluation. The results showed that SPCL-WS scaffolds seem to induce a slight lower inflammatory/immune reaction in both types of implantation models. Nonetheless, comparing the two models, the IM implantation resulted in a slightly higher inflammatory response than the SC implantation with early activation of the lymph nodes. The overall data suggests a good integration of the materials in the host, independently of the tissue location with a normal progress of the reaction for all the conditions. PMID: 20601228 [PubMed - as supplied by publisher] | | |
| Comprehension of ECM-Cell dynamics; A prerequisite for tissue regeneration.
July 6, 2010 at 6:50 AM
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| | Comprehension of ECM-Cell dynamics; A prerequisite for tissue regeneration. Biotechnol Adv. 2010 Jun 18; Authors: Dutta RC, Dutta AK Tissue regeneration and cell therapy has an enormous potential in healthcare through the creation of artificial human tissues and organs. Possibility of producing functional replica of tissues and organs can offer a common, solitary solution for various kinds of inflictions. It can also provide an ultimate test model for drug discovery. There exists convincing evidence that if cells are cultured in extra cellular matrix (ECM) mimicking 3D scaffolds infused with tissue specific biochemical cues they grow and differentiate to express functionality. However, comprehensive understanding of ECM and its dynamic relation with the growing cells is vital for creating functional tissue models ex vivo. Different medical and non-medical groups all over the world are working towards achieving affordable, user friendly and technically viable solutions for improving our understanding of Cell-ECM dynamics for tissue engineering (TE). Successful TE, an ambitious goal that includes tissue neogenesis in vitro and functional tissue mending (regenerative medicine) in vivo, however involves innumerable challenges. Present review discusses some of the major technical hurdles that hinder the pace of progress in tissue regeneration/engineering (TE). PMID: 20600786 [PubMed - as supplied by publisher] | | |
| Intracellular ice formation in confluent monolayers of human dental stem cells and membrane damage.
July 6, 2010 at 6:50 AM
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| | Intracellular ice formation in confluent monolayers of human dental stem cells and membrane damage. Cryobiology. 2010 Jun 22; Authors: Zhurova M, Woods EJ, Acker JP Dental pulp stem cells (DPSCs) are of interest to researchers and clinicians due to their ability to differentiate into various tissue types and potential uses in cell-mediated therapies and tissue engineering. Currently DPSCs are cryopreserved in suspension using Me2SO. However, preservation as two and three dimensional constructs, along with the elimination of toxic Me2SO, may be required. It was shown that intracellular ice formation (IIF), lethal to cells in suspensions, may be innocuous in cell monolayers due to ice propagation between cells through gap junctions, that results in improved postthaw recovery. We hypothesized that innocuous IIF protects confluent DPSC monolayers against injury during cryopreservation. The objective was to examine the effects of IIF on post-thaw viability of both confluent monolayers and suspensions of DPSCs. Confluent DPSC monolayers were assessed for the expression of gap junction protein Connexin-43. IIF was induced on the cryostage and in the methanol bath at different subzero temperatures. Membrane integrity and colony forming ability were assessed post-thaw. Confluent DPSC monolayers expressed Connexin-43. In cell suspensions, 85.9+/-1.7% of cells were damaged after 100% IIF. In cell monolayers, after 100% IIF, only 25.5+/-5.5% and 14.8+/-3.3% of cells were damaged on the cryostage and in the methanol bath respectively. However, DPSC monolayers exposed to 100% IIF showed no colony forming ability. We conclude that confluent monolayers of DPSCs express the gap junction-forming protein Connexin-43 and upon IIF retain membrane integrity, however lose the ability to proliferate. PMID: 20599884 [PubMed - as supplied by publisher] | | |
| Rapid construction of mechanically- confined multi- cellular structures using dendrimeric intercellular linker.
July 6, 2010 at 6:50 AM
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| | Rapid construction of mechanically- confined multi- cellular structures using dendrimeric intercellular linker. Biomaterials. 2010 Jul 2; Authors: Mo X, Li Q, Yi Lui LW, Zheng B, Kang CH, Nugraha B, Yue Z, Jia RR, Fu HX, Choudhury D, Arooz T, Yan J, Lim CT, Shen S, Hong Tan C, Yu H Tissue constructs that mimic the in vivo cell-cell and cell-matrix interactions are especially useful for applications involving the cell- dense and matrix- poor internal organs. Rapid and precise arrangement of cells into functional tissue constructs remains a challenge in tissue engineering. We demonstrate rapid assembly of C3A cells into multi- cell structures using a dendrimeric intercellular linker. The linker is composed of oleyl- polyethylene glycol (PEG) derivatives conjugated to a 16 arms- polypropylenimine hexadecaamine (DAB) dendrimer. The positively charged multivalent dendrimer concentrates the linker onto the negatively charged cell surface to facilitate efficient insertion of the hydrophobic oleyl groups into the cellular membrane. Bringing linker- treated cells into close proximity to each other via mechanical means such as centrifugation and micromanipulation enables their rapid assembly into multi- cellular structures within minutes. The cells exhibit high levels of viability, proliferation, three- dimensional (3D) cell morphology and other functions in the constructs. We constructed defined multi- cellular structures such as rings, sheets or branching rods that can serve as potential tissue building blocks to be further assembled into complex 3D tissue constructs for biomedical applications. PMID: 20599265 [PubMed - as supplied by publisher] | | |
| No effect in combining chondrogenic predifferentiation and mechanical cyclic compression on osteochondral constructs stimulated in a bioreactor.
July 6, 2010 at 6:50 AM
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| | No effect in combining chondrogenic predifferentiation and mechanical cyclic compression on osteochondral constructs stimulated in a bioreactor. Ann Anat. 2010 Jun 11; Authors: Budde S, Jagodzinski M, Wehmeier M, Hurschler C, Richter B, Broese M, Paulsen F, Tschernig T, Krettek C, Haasper C Traumatic and degenerative osteochondral lesions are a common problem in orthopaedic surgery. The concept of tissue engineering represents the possibility of a promising therapeutical approach. The purpose of this study has been to improve the characteristics of osteochondral grafts consisting of a human certified collagen I-bone hybrid matrix seeded with human bone marrow stromal cells and stimulated in a custom-made biomechanoreactor. This study was undertaken as a follow-up to our prior studies. Based on our established system, we added chondrogenic growth factors (IGF-1 and TGF-beta(2)) and evaluated their effect on chondrogenic differentiation. Constructs were stimulated for 14, 21 and 28 days respectively by different protocols, including cyclic mechanical stimulation, hormonal stimulation or a combination of both. More than 70% of the cells were viable throughout the entire experimental period. Histological analysis revealed a homogeneous distribution of cells in a cartilage-like matrix organization. Immunohistological collagen II staining was positive irrespective of stimulation manner and time. Levels of DNA and glycosaminoglycans, having been normalized to DNA, did not change. Analysis of the biomechanical stiffness after 14 days showed increased stiffness in the hormonally and mechanically stimulated group compared to the static group. Stimulation time did not have a significant influence. The media supplements to foster the quality of the tissue tested here did not show any progress in our system. We conclude that cyclic compression enhances matrix stiffness, but stimulation time should be kept short and growth factors should be left out in this system with regard to clinical applicability and financial concerns. PMID: 20598515 [PubMed - as supplied by publisher] | | |
| A rabbit anterior cornea replacement derived from acellular porcine cornea matrix, epithelial cells and keratocytes.
July 6, 2010 at 6:50 AM
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| | A rabbit anterior cornea replacement derived from acellular porcine cornea matrix, epithelial cells and keratocytes. Biomaterials. 2010 Jun 30; Authors: Pang K, Du L, Wu X The aim of this study was to construct a rabbit anterior cornea replacement with an acellular porcine cornea matrix (APCM) as a scaffold. The scaffold was prepared from fresh porcine corneas which were treated with 0.5% (wt./vol.) sodium dodecyl sulfate (SDS) solution and stirred for 24 h in a 4 degrees C refrigeration chamber. The complete removal of corneal cells was confirmed by H&E and DAPI staining. The stroma structure and mechanical properties were well preserved. The extracts had no cytotoxicity to rabbit corneal keratocytes, epithelial and endothelial cells as determined by MTT assay. Moreover, there was no sign that an immune reaction occurred in or around the transplanted disks within 6 months of animal implantation. To construct a rabbit anterior cornea replacement, keratocytes were injected into APCM and cultured for 7 days in a dynamic culturing system, followed by culturing corneal epithelial cells on the stroma construct surface for another 7 days. The phenotype of the construct was similar to normal rabbit corneas, with high expression of cytokeratin 3 in the epithelial cell layer and expression of vimentin in the stromal cells. These results suggested that the APCM developed by using SDS might be a suitable scaffold for cornea tissue engineering. PMID: 20598368 [PubMed - as supplied by publisher] | | |
| Influence of Chondrocytes on the Chondrogenic Differentiation of Adipose Stem Cells.
July 6, 2010 at 6:50 AM
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| | Influence of Chondrocytes on the Chondrogenic Differentiation of Adipose Stem Cells. Tissue Eng Part A. 2010 Jul 3; Authors: Lee JS, Im GI In the current study, whether or not chondrogenic differentiation of ASCs could be enhanced by soluble factors from or co-culture with chondrocytes was determined. In vitro pellet cultures were carried out in five ways using ASCs or chondrocytes in passage 3, as follows: #1, 2.5 x 10<sup>5</sup> ASCs were cultured in DMEM/F-12 supplemented with 1% ITS, 10<sup>-7 </sup>M dexamethasone, 50 muM ascorbate-2-phosphate, 50 muM L-proline, 1 mM sodium pyruvate; #2, 2.5 x 10<sup>5</sup> chondrocytes were cultured in the same medium as #1: #3, 1.25 x 10<sup>5</sup> ASCs and 1.25 x 10<sup>5</sup> chondrocytes were mixed and co-cultured in the same medium as #1; #4, 2.5 x 10<sup>5</sup> ASCs were cultured in a medium which was a 1:1 mixture of the same fresh medium as #1 and conditioned medium from chondrocyte culture (#2); #5, 2.5 x 10<sup>5</sup> ASCs were cultured in the same medium as #1 plus 5 ng/ml of TGF-beta2 and 100 ng/ml of BMP-7. After 3 weeks, the GAG level normalized to the DNA amount was significantly increased by 25% in ASCs treated with condition medium from chondrocyte cultures (p=0.028) and 37% from ASC-chondrocyte co-cultures (p=0.042). The GAG level was 37% greater in chondrocytes (p=0.046) and 50% greater in ASCs cultured under growth factor cocktails than the control ASCS. The gene expression of SOX-9 significantly increased by > 10-fold (p<0.05) in ASCs treated with the conditioned medium from chondrocyte cultures and ASC-chondrocyte co-cultures compared with the control ASCs, while COL2A1 significantly increased approximately 100-fold (p<0.05) in either condition. COL10A1 gene expression increased by either treating with conditioned medium or by co-culture (p<0.05), but COL1A1 gene expression did not significantly change in either condition. Western blotting of SOX-9 and immunochemistry for Types II, I, and X collagen largely parallel the results from gene expression studies. It is concluded that that the signals from chondrocytes, in the form of soluble factors or by direct interaction, effectively promote chondrogenic differentiation of ASCs during in vitro pellet culture. This work may present a simple and innovative method for generating cartilaginous tissue from ASC, and shed a new light in cartilage tissue engineering from ASCs. PMID: 20597811 [PubMed - as supplied by publisher] | | |
| Chitosan produces potent neuroprotection and physiological recovery following traumatic spinal cord injury.
July 6, 2010 at 6:50 AM
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| | Chitosan produces potent neuroprotection and physiological recovery following traumatic spinal cord injury. J Exp Biol. 2010 May;213(Pt 9):1513-20 Authors: Cho Y, Shi R, Borgens RB Chitosan, a non-toxic biodegradable polycationic polymer with low immunogenicity, has been extensively investigated in various biomedical applications. In this work, chitosan has been demonstrated to seal compromised nerve cell membranes thus serving as a potent neuroprotector following acute spinal cord trauma. Topical application of chitosan after complete transection or compression of the guinea pig spinal cord facilitated sealing of neuronal membranes in ex vivo tests, and restored the conduction of nerve impulses through the length of spinal cords in vivo, using somatosensory evoked potential recordings. Moreover, chitosan preferentially targeted damaged tissues, served as a suppressor of reactive oxygen species (free radical) generation, and the resultant lipid peroxidation of membranes, as shown in ex vivo spinal cord samples. These findings suggest a novel medical approach to reduce the catastrophic loss of behavior after acute spinal cord and brain injury. PMID: 20400636 [PubMed - indexed for MEDLINE] | | |
| CIRM's Self Interest Demands More Openness
July 6, 2010 at 12:31 AM
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| Cobbling together a $3 billion research program from scratch is no simple task. No chairs, no phones, no computers, no payroll system but no employees either or, for that matter, an office – that was picture more than five years ago when the California stem cell agency launched its unprecedented enterprise.
Adding to CIRM's teething problems were the state's "sunshine" laws. They require the | | |
| The Agenda from the Incident at the Marriott
July 6, 2010 at 12:24 AM
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| CIRM barred two academics from a meeting last month in what appears to be a violation of the state open meeting laws. Below is the agenda, as provided by the two, for the meeting that they were attempting to attend.
A scientist from New York and one from Australia were on the panel at the meeting, whose topics included the level of reimbursement for human egg donors, a subject that readily | | | | 
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