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| Self-Assembly-Peptide Hydrogels as Tissue-Engineering Scaffolds for Three-Dimensional Culture of Chondrocytes in vitro.
June 17, 2010 at 7:01 AM
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| | Self-Assembly-Peptide Hydrogels as Tissue-Engineering Scaffolds for Three-Dimensional Culture of Chondrocytes in vitro. Macromol Biosci. 2010 Jun 15; Authors: Liu J, Song H, Zhang L, Xu H, Zhao X The promising potential of a RAD-16 self-assembly-peptide hydrogel as a scaffold for tissue-engineered cartilage was investigated. Within 3 weeks of in vitro culture, chondrocytes within the hydrogel produced a high amount of GAG and type-II collagen, which are the components of cartilage-specific extracellular matrix (ECM). With the culture time increased, toluidine-blue staining for GAG and immuno-histochemistry staining for type-II collagen of the chondrocytes-hydrogel composites became more intense. Analysis of the gene expression of the ECM molecules also confirmed the chondrocytes in the peptide hydrogel maintained their phenotype within 3 weeks of in vitro culture. PMID: 20552605 [PubMed - as supplied by publisher] | | |
| Feeder-independent culture of mouse embryonic stem cells using vitamin a/retinol.
June 17, 2010 at 7:01 AM
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| | Feeder-independent culture of mouse embryonic stem cells using vitamin a/retinol. Methods Mol Biol. 2010;652:75-83 Authors: Khillan JS, Chen L Embryonic stem (ES) cells derived from the inner cell mass of a mammalian blastocyst represent unlimited source of all types of cells for regenerative medicine and for drug discovery. Mouse and human ES cells require mouse embryonic fibroblast feeder cells to maintain their undifferentiated state which involve additional time-consuming and labor-intensive steps. Recently we reported a novel function of retinol, the alcohol form of vitamin A, in preventing the differentiation of mouse ES cells. Retinol/vitamin A induces the overexpression of Nanog, a key transcription factor that is important for maintaining the pluripotency of mouse and human ES cells. Further, retinol/vitamin A also supports feeder-independent culture of ES cells in long-term cultures. The cells continue to maintain the expression of pluripotent cell-specific markers such as Nanog, Oct4, and Sox2 and form chimeric animals after injection into blastocysts. In this chapter, we describe feeder-independent cultures of mouse ES cells in the medium supplemented with retinol. The ES cells are cultured over plates coated with gelatin in ES medium with leukemia inhibitory factor (LIF) which is supplemented with 0.5 muM retinol/vitamin A. The cells are passaged every 3-5 days by trypsinization. The pluripotency of the cells is tested by different undifferentiated ES cell-specific markers. PMID: 20552422 [PubMed - in process] | | |
| Adhesion and proliferation of skeletal muscle cells on single layer poly(lactic acid) ultra-thin films.
June 17, 2010 at 7:01 AM
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| | Adhesion and proliferation of skeletal muscle cells on single layer poly(lactic acid) ultra-thin films. Biomed Microdevices. 2010 Jun 16; Authors: Ricotti L, Taccola S, Pensabene V, Mattoli V, Fujie T, Takeoka S, Menciassi A, Dario P An increasing interest in bio-hybrid systems and cell-material interactions is evident in the last years. This leads towards the development of new nano-structured devices and the assessment of their biocompatibility. In the present study, the development of free-standing single layer poly(lactic acid) (PLA) ultra-thin films is described, together with the analysis of topography and roughness properties. The biocompatibility of the PLA films has been tested in vitro, by seeding C2C12 skeletal muscle cells, and thus assessing cells shape, density and viability after 24, 48 and 72 h. The results show that free-standing flexible PLA nanofilms represent a good matrix for C2C12 cells adhesion, spreading and proliferation. Early differentiation into myotubes is also allowed. The biocompatibility of the novel ultra-thin films as substrates for cell growth promotes their application in the fields of regenerative medicine, muscle tissue engineering, drug delivery, and-in general-in the field of bio-hybrid devices. PMID: 20552402 [PubMed - as supplied by publisher] | | |
| Stem cell therapies for spinal cord injury.
June 17, 2010 at 7:01 AM
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| | Stem cell therapies for spinal cord injury. Nat Rev Neurol. 2010 Jun 15; Authors: Sahni V, Kessler JA Stem cell therapy is a potential treatment for spinal cord injury (SCI), and a variety of different stem cell types have been evaluated in animal models and humans with SCI. No consensus exists regarding the type of stem cell, if any, that will prove to be effective therapeutically. Most data suggest that no single therapy will be sufficient to overcome all the biological complications caused by SCI. Rationales for therapeutic use of stem cells for SCI include replacement of damaged neurons and glial cells, secretion of trophic factors, regulation of gliosis and scar formation, prevention of cyst formation, and enhancement of axon elongation. Most therapeutic approaches that use stem cells involve implantation of these cells into the spinal cord. The attendant risks of stem cell therapy for SCI-including tumor formation, or abnormal circuit formation leading to dysfunction-must be weighed against the potential benefits of this approach. This Review will examine the biological effects of SCI, the opportunities for stem cell treatment, and the types of stem cells that might be used therapeutically. The limited information available on the possible benefits of stem cell therapy to humans will also be discussed. PMID: 20551948 [PubMed - as supplied by publisher] | | |
| Fast and Forceful Refolding of Stretched alpha-Helical Solenoid Proteins.
June 17, 2010 at 7:01 AM
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| | Fast and Forceful Refolding of Stretched alpha-Helical Solenoid Proteins. Biophys J. 2010 Jun 16;98(12):3086-3092 Authors: Kim M, Abdi K, Lee G, Rabbi M, Lee W, Yang M, Schofield CJ, Bennett V, Marszalek PE Anfinsen's thermodynamic hypothesis implies that proteins can encode for stretching through reversible loss of structure. However, large in vitro extensions of proteins that occur through a progressive unfolding of their domains typically dissipate a significant amount of energy, and therefore are not thermodynamically reversible. Some coiled-coil proteins have been found to stretch nearly reversibly, although their extension is typically limited to 2.5 times their folded length. Here, we report investigations on the mechanical properties of individual molecules of ankyrin-R, beta-catenin, and clathrin, which are representative examples of over 800 predicted human proteins composed of tightly packed alpha-helical repeats (termed ANK, ARM, or HEAT repeats, respectively) that form spiral-shaped protein domains. Using atomic force spectroscopy, we find that these polypeptides possess unprecedented stretch ratios on the order of 10-15, exceeding that of other proteins studied so far, and their extension and relaxation occurs with minimal energy dissipation. Their sequence-encoded elasticity is governed by stepwise unfolding of small repeats, which upon relaxation of the stretching force rapidly and forcefully refold, minimizing the hysteresis between the stretching and relaxing parts of the cycle. Thus, we identify a new class of proteins that behave as highly reversible nanosprings that have the potential to function as mechanosensors in cells and as building blocks in springy nanostructures. Our physical view of the protein component of cells as being comprised of predominantly inextensible structural elements under tension may need revision to incorporate springs. PMID: 20550922 [PubMed - as supplied by publisher] | | |
| Biomarker use in tailored combat casualty care.
June 17, 2010 at 7:01 AM
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| | Biomarker use in tailored combat casualty care. Biomark Med. 2010 Jun;4(3):465-73 Authors: Brown TS, Safford S, Caramanica J, Elster EA Modern war wounds are complex and primarily involve extremities. They require multiple operative interventions to achieve wound closure and begin rehabilitation. Current assessment of the suitability of surgical wound closure is based upon subjective methods coupled with a semiquantitative determination of the wound bacterial burden. Measurement of the systemic and local response to injury using inflammatory biomarkers may allow for accelerated wound closure and treatment of other combat-related morbidity. This article presents the introduction of personalized medicine into combat casualty care. PMID: 20550480 [PubMed - in process] | | |
| Amino acid sequence requirements of laminin ss1 chain peptide B133 (DISTKYFQMSLE) for amyloid-like fibril formation, syndecan binding, and neurite outgrowth promotion.
June 17, 2010 at 7:01 AM
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| | Amino acid sequence requirements of laminin ss1 chain peptide B133 (DISTKYFQMSLE) for amyloid-like fibril formation, syndecan binding, and neurite outgrowth promotion. Biochemistry. 2010 Jun 15; Authors: Katagiri F, Takeyama K, Ohga Y, Hozumi K, Kikkawa Y, Kadoya Y, Nomizu M Peptide B133 (DSITKYFQMSLE), derived from mouse laminin ss1 chain (1298--1309), promotes cell attachment, neurite outgrowth, and amyloid-like fibril formation. Previously, we showed that the N-terminal Asp-deleted peptide B133a (SITKYFQMSLE) promotes integrin alpha2beta1-mediated cell attachment and spreading but does not form amyloid-like fibrils, and that the C-terminal Glu-deleted peptide B133g (DSITKYFQMSL) attaches cells without cell spreading and forms amyloid-like fibrils. In this study, we further investigated the amino acid sequence requirements of B133 for biological function using a set of truncated and Ala-substituted peptides. Cell attachment to B133g was inhibited by only heparin, and Congo red analysis indicated that the amyloid-like fibril formation activity of B133g was stronger than that of B133. Alanine scan analysis for the B133g peptide indicated that Asp and Ile residues are essential for cell attachment. Additionally, the N-terminus Asp residue was required for neurite outgrowth. Further, amyloid-like fibril formation required Asp and Ile residues. These data suggest that the cell attachment activity of B133g is required for the amyloid-like fibril formation. We also evaluated cell attachment to the peptides using syndecans and glypican over-expressing cells. B133g attached to syndecan-over-expressing cells but not to glypican-over-expressing cells, suggesting that the amyloidogenic peptides promote syndecan-mediated cell attachment. These findings were useful to clarify the mechanism of amyloid-like fibril formation and the biological functions. The B133 peptide promotes amyloid-like fibril formation, syndecan-mediated cell attachment, and neurite outgrowth, and has a potential for use as a biomaterial for tissue engineering. PMID: 20550135 [PubMed - as supplied by publisher] | | |
| Cellular therapy in 2010: focus on autoimmune and cardiac diseases.
June 17, 2010 at 7:01 AM
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| | Cellular therapy in 2010: focus on autoimmune and cardiac diseases. Isr Med Assoc J. 2010 Feb;12(2):110-5 Authors: Perl L, Weissler A, Mekori YA, Mor A Stem cell therapy has developed extensively in recent years, leading to several new clinical fields. The use of mesenchymal stromal cells sparks special interest, as it reveals the importance of the paracrine and immunomodulatory effects of these supporting cells, in disease and in cure. This review discusses our current understanding of the basic clinical principles of stem cell therapy and demonstrates the broad range of this treatment modality by examining two relatively new therapeutic niches--autoimmune and cardiac diseases. PMID: 20550037 [PubMed - in process] | | |
| Critical role of tissue mast cells in controlling long-term glucose sensor function in vivo.
June 17, 2010 at 7:01 AM
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| | Critical role of tissue mast cells in controlling long-term glucose sensor function in vivo. Biomaterials. 2010 Jun;31(16):4540-51 Authors: Klueh U, Kaur M, Qiao Y, Kreutzer DL Little is known about the specific cells, mediators and mechanisms involved in the loss of glucose sensor function (GSF) in vivo. Since mast cells (MC) are known to be key effector cells in inflammation and wound healing, we hypothesized that MC and their products are major contributors to the skin inflammation and wound healing that controls GSF at sites of sensor implantation. To test this hypothesis we utilized a murine model of continuous glucose monitoring (CGM) in vivo in both normal C57BL/6 mice (mast cell sufficient), as well as mast cell deficient B6.Cg-Kit(W-sh)/HNihrJaeBsmJ (Sash) mice over a 28 day CGM period. As expected, both strains of mice displayed excellent CGM for the first 7 days post sensor implantation (PSI). CGM in the mast cell sufficient C57BL/6 mice was erratic over the remaining 21 days PSI. CGM in the mast cell deficient Sash mice displayed excellent sensor function for the entire 28 day of CGM. Histopathologic evaluation of implantation sites demonstrated that tissue reactions in Sash mice were dramatically less compared to the reactions in normal C57BL/6 mice. Additionally, mast cells were also seen to be consistently associated with the margins of sensor tissue reactions in normal C57BL/6 mice. Finally, direct injection of bone marrow derived mast cells at sites of sensor implantation induced an acute and dramatic loss of sensor function in both C57BL/6 and Sash mice. These results demonstrate the key role of mast cells in controlling glucose sensor function in vivo. PMID: 20226521 [PubMed - indexed for MEDLINE] | | |
| Tickled PINK1: mitochondrial homeostasis and autophagy in recessive Parkinsonism.
June 17, 2010 at 7:01 AM
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| | Tickled PINK1: mitochondrial homeostasis and autophagy in recessive Parkinsonism. Biochim Biophys Acta. 2010 Jan;1802(1):20-8 Authors: Chu CT Dysregulation of mitochondrial structure and function has emerged as a central factor in the pathogenesis of Parkinson's disease and related parkinsonian disorders (PD). Toxic and environmental injuries and risk factors perturb mitochondrial complex I function, and gene products linked to familial PD often affect mitochondrial biology. Autosomal recessive mutations in PTEN-induced kinase 1 (PINK1) cause an L-DOPA responsive parkinsonian syndrome, stimulating extensive interest in the normal neuroprotective and mitoprotective functions of PINK1. Recent data from mammalian and invertebrate model systems converge upon interactions between PINK1 and parkin, as well as DJ-1, alpha-synuclein and leucine rich repeat kinase 2 (LRRK2). While all studies to date support a neuroprotective role for wild type, but not mutant PINK1, there is less agreement on subcellular compartmentalization of PINK1 kinase function and whether PINK1 promotes mitochondrial fission or fusion. These controversies are reviewed in the context of the dynamic mitochondrial lifecycle, in which mitochondrial structure and function are continuously modulated not only by the fission-fusion machinery, but also by regulation of biogenesis, axonal/dendritic transport and autophagy. A working model is proposed, in which PINK1 loss-of-function results in mitochondrial reactive oxygen species (ROS), cristae/respiratory dysfunction and destabilization of calcium homeostasis, which trigger compensatory fission, autophagy and biosynthetic repair pathways that dramatically alter mitochondrial structure. Concurrent strategies to identify pathways that mediate normal PINK1 function and to identify factors that facilitate appropriate compensatory responses to its loss are both needed to halt the aging-related penetrance and incidence of familial and sporadic PD. PMID: 19595762 [PubMed - indexed for MEDLINE] | | |
| The role of redox regulation in the normal physiology and inflammatory diseases of skin.
June 17, 2010 at 7:01 AM
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| | The role of redox regulation in the normal physiology and inflammatory diseases of skin. Front Biosci (Elite Ed). 2009;1:123-41 Authors: Korkina L, Pastore S Skin is the largest organ which contains complex and tightly regulated redox network of the reactive oxygen/nitrogen/lipid species producing components as well as the redox damage protective systems. This redox balancing system has evolved to regulate normal physiological processes and to protect skin and the internal organs against environmental damage. Exposure to some physical, chemical, and biological agents results in the excessive formation of free radicals and non-radical redox active species within the skin. Normally, skin reacts to this overproduction by sacrificing non-enzymatic antioxidants and by adaptive induction of both protective detoxifying and damage-eliminating systems. Thus, fast restoration of redox balance necessary to maintain normal skin structure and functioning occurs. In the case of excessive exposure or defects in the adaptive reactions, redox damage to skin components occurs. Here, we focus on the role of redox status in the acute inflammatory response to wounding and chronic inflammatory skin diseases such as psoriasis, atopic and contact dermatitis. Redox-mediated chronic inflammation and immunosuppression as risk factors for tumorigenesis are also reviewed. PMID: 19482631 [PubMed - indexed for MEDLINE] | | |
| Effect of collagen hydrolysate on chondrocyte-seeded agarose constructs.
June 17, 2010 at 7:01 AM
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| | Effect of collagen hydrolysate on chondrocyte-seeded agarose constructs. Biomed Mater Eng. 2009 Jan 1;19(6):409-14 Authors: Elder SH, Borazjani A The mechanical properties of engineered cartilage are strongly dependent on collagen content, but the collagen to glycosaminoglycan ratio in engineered cartilage is often much lower than that of the native tissue. Therefore culture medium supplements which increase collagen production by chondrocytes are of interest. It had previously been reported that collagen hydrolysate stimulated type II collagen biosynthesis in short-term, high density monolayer chondrocyte cultures. It was hypothesized that collagen hydrolysate added to the culture medium of three dimensional chondrocyte-agarose constructs would enhance their mechanical properties. Porcine articular chondrocytes were embedded in 2% agarose and cultured for up to 6 weeks with and without 1 mg/ml collagen hydrolysate. The instantaneous compressive modulus and equilibrium compressive modulus were significantly lower in the collagen hydrolysate-treated constructs, consistent with the finding of lower collagen and GAG content. Contrary to our hypothesis, our results indicate that 1 mg/ml collagen hydrolysate may actually inhibit macromolecule biosynthesis and be detrimental to the mechanical properties of long term chondrocyte-agarose constructs. PMID: 20231793 [PubMed - indexed for MEDLINE] | | |
| A modular culture system for the generation of multiple specialized tissues.
June 17, 2010 at 2:01 AM
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| | A modular culture system for the generation of multiple specialized tissues. Biomaterials. 2010 Apr;31(11):2945-54 Authors: Minuth WW, Denk L, Glashauser A Numerous factors influence cell functions and tissue development in culture. A modular culture system has been developed to allow the control of many of these important environmental parameters. Optimal adhesion of cells is obtained by selecting an individual biomaterial. Selected specimens are mounted in a tissue carrier in order to protect it against damage during handling and after seeding cells, the carriers can be used in a series of compatible perfusion culture containers. This technique allows the simple bathing of growing tissue under continuous medium transport and the exposure of epithelia to a gradient with different fluids at the luminal and basal sides. A further container is made of transparent material to observe microscopically the developing tissue. In addition, a special model features a flexible silicone lid to apply force to mimic the mechanical load required for developing connective and muscular tissue. Perfusion culture of stem/progenitor cells at the interface of an artificial interstitium made by a polyester fleece results in the spatial development of tubules. During long term culture over weeks the growing tissue is continuously exposed to fresh nutrition and respiratory gas. The medium is transported in a constant flow or in pulses, preventing unstirred layers of fluid. A variety of applications of this modular system, described in this paper, demonstrates that the biological profile of cells and tissues can be strongly improved when perfusion culture with a permanent provision of fresh medium is applied. PMID: 20096452 [PubMed - indexed for MEDLINE] | | | | 
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