| Detrusor myocyte activity and afferent signaling.
December 22, 2009 at 8:49 am
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| | Detrusor myocyte activity and afferent signaling. Neurourol Urodyn. 2009 Dec 18;29(1):97-106 Authors: Andersson KE AIMS: To discuss (1) mechanisms involved in the generation and control of myocyte contractions and consequent afferent nerve activity and (2) these mechanisms as targets for drugs aimed for treatment of overactive bladder (OAB) symptoms and detrusor overactivity (DO). METHODS: Literature review of myocyte activation, bladder afferent nerves, mediators in the bladder, and translational aspects of the findings. RESULTS: During bladder filling, there is normally no parasympathetic outflow from the spinal cord. Despite this, the bladder develops tone during filling and also exhibits non-synchronized local contractions and relaxations that are caused by a basal myogenic mechanical activity that may be reinforced by release of, for example, acetylcholine from non-neuronal and/or neuronal sources or local mediators, such as prostaglandins and endothelins. It is suggested that these spontaneous contractions are able to generate activity in afferent nerves ("afferent noise") that may contribute to DO and OAB. CONCLUSIONS: Spontaneous bladder myocyte contractions and factors that are able to modulate them, as well as the consequent afferent nerve activity, may be targets for drugs meant for treatment of OAB/DO. Neurourol. Urodynam. 29: 97-106, 2010. (c) 2009 Wiley-Liss, Inc. PMID: 20025035 [PubMed - as supplied by publisher] |
| In vitro studies on the influence of surface modification of Ni-Ti alloy on human bone cells.
December 22, 2009 at 8:49 am
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| | In vitro studies on the influence of surface modification of Ni-Ti alloy on human bone cells. J Biomed Mater Res A. 2009 Dec 18; Authors: Chrzanowski W, Neel EA, Armitage DA, Zhao X, Knowles JC, Salih V The in vitro cell behavior on Nitinol after different surface treatments was investigated. As references samples, commercially pure titanium (cpTi) and bioactive titanium were used. The surface treatments influenced the topography, surface energy, crystallographic structure, ion release, chemistry, and ability to form apatite layer from simulated body fluids. Regardless of the surface treatment, the bioactivity study showed that the kinetics of apatite film formation was similar for all tested samples. No clear indication of the surface characteristics influence on the ability for calcium-phosphate precipitation was evident. Cell activity studies showed that ground nickel titanium, spark oxidized and thermally oxidized (at 400 degrees C and below) had higher cellular activity and caused increased alkaline phosphatase (ALP) and osteocalcin (OC) expression which was comparable to control tissue culture plastic and titanium reference samples. Regardless of surface modifications, preimmersion of the samples in media for 72 h resulted in cell proliferation at the same level for all samples. Therefore, it can be concluded that preconditioning of samples alters surface properties and modulates the cell response regardless of the initial surface treatment and its properties. Moreover, a detrimental effect on cell response was observed after 7 and 14 days in culture for alkali treated samples. This was attributed to a high surface nickel concentration and a high nickel ion release rate from these surfaces. (c) 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20024896 [PubMed - as supplied by publisher] |
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December 22, 2009 at 8:49 am
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Analyst. 2010 Jan 14;135(1):182-188 Authors: Rakmanee T, Olsen I, Griffiths GS, Donos N Large amounts of biological samples are usually required to measure multiple components by the enzyme-linked immunosorbant assay. However, the amounts of many tissue extracts and fluids, including gingival crevicular fluid (GCF), are generally extremely small. The aim of this study was, therefore, to develop and validate a novel multiplex bead assay (MBA) to simultaneously measure a profile of healing-related mediators in the GCF of treated periodontal wounds. An MBA was developed and validated by assessment of assay selectivity, recovery, precision and sensitivity, using eight recombinant human growth mediators as assay standards. GCF samples were collected on paper strips from healing wound (test) and healthy unaffected (control) sites of 15 patients with periodontitis, seven days post-periodontal surgery. Each GCF sample was eluted and the levels of the mediators measured using the MBA and antibody pairs specific for angiopoietin-1, vascular endothelial growth-factor, bone morphogenetic protein-2, osteoprotegerin, tissue inhibitor of metalloprotease-1 (TIMP-1), basic fibroblast growth-factor, keratinocyte growth-factor, and platelet derived growth-factor. Less than 1.8% of cross-reactivity was observed between antibodies and the eight different analytes, for which the recovery was more than 85%. Mean intra- and inter-assay precision were within the acceptance criteria of 20% and 25%, respectively. Detection of all mediators was highly sensitive (</=70 ng/L) except for TIMP-1 (215 ng/L). Angiogenic factors were the most highly secreted in the GCF seven days post-surgery. This new MBA can simultaneously measure small amounts of eight different growth mediators in the GCF of healing periodontal wounds. It might also be a valuable tool for evaluating the components of wound fluids as a prognostic indicator of the success of therapeutic intervention. PMID: 20024200 [PubMed - as supplied by publisher] |
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December 22, 2009 at 8:49 am
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Lab Chip. 2010 Jan 7;10(1):116-122 Authors: Keenan TM, Frevert CW, Wu A, Wong V, Folch A During inflammation neutrophils rapidly migrate to the site of tissue damage or infection by following complex gradients of bacterial peptides and host-derived chemokines. The efficiency and speed of neutrophil migration is critically dependent upon the ability of neutrophils to sense new gradients and utilize only those that provide the most direct path to the damaged or infected site. Receptor desensitization plays an important role in migration efficiency and is most commonly studied using bath application of chemotactic factor solutions instead of presenting cells with gradients analogous to those they would experience in vivo. Here we describe a new method for examining gradient-induced neutrophil desensitization using a previously-developed open-chamber microfluidic gradient generator. PMID: 20024059 [PubMed - as supplied by publisher] |
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December 22, 2009 at 8:49 am
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Lab Chip. 2010 Jan 7;10(1):36-42 Authors: Jang KJ, Suh KY We have developed a simple multi-layer microfluidic device by integrating a polydimethyl siloxane (PDMS) microfluidic channel and a porous membrane substrate to culture and analyze the renal tubular cells. As a model cell type, primary rat inner medullary collecting duct (IMCD) cells were cultured inside the channel. To generate in vivo-like tubular environments for the cells, a fluidic shear stress of 1 dyn/cm(2) was applied for 5 hours, allowing for optimal fluidic conditions for the cultured cells, as verified by enhanced cell polarization, cytoskeletal reorganization, and molecular transport by hormonal stimulations. These results suggest that the microfluidic device presented here is useful for resembling an in vivo renal tubule system and has potential applications in drug screening and advanced tissue engineering. PMID: 20024048 [PubMed - as supplied by publisher] |
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December 22, 2009 at 8:49 am
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Chem Soc Rev. 2010 Jan 14;39(1):354-378 Authors: Robertus J, Browne WR, Feringa BL In complex organisms, cells are often dependent on their extracellular matrix (ECM) for structural integrity, the mechanical properties of tissues, and for signaled regulation of cellular processes including adhesion, migration, growth, secretion, gene expression and apoptosis. Achieving dynamic control, i.e. by using an external stimulus, over the interactions between cells and artificial interfaces holds considerable promise in tissue engineering, medicine, cell biology and immunology. For example, improved spatial control over cell-surface interaction is potentially useful in the design of cell-based screening devices. Dynamic control over SAMs for cell adhesion provides an additional handle to direct and study the attachment of cells to surfaces, e.g., in studying cell spreading from a predetermined pattern in order to screen the cytotoxicity of drug candidates. However, 'reversible' control of cell adhesion onto substrates is an area that is still in its infancy. In this critical review recent developments in cell adhesion of mammalian cells to SAM-modified surfaces, the physical properties of which can be controlled by an external stimulus, e.g. by light, electrochemistry, etc., are discussed (118 references). PMID: 20023857 [PubMed - as supplied by publisher] |
| Surface topography induces 3D self-orientation of cells and extracellular matrix resulting in improved tissue function.
December 22, 2009 at 8:49 am
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| | Surface topography induces 3D self-orientation of cells and extracellular matrix resulting in improved tissue function. Integr Biol (Camb). 2009 Feb;1(2):196-204 Authors: Guillemette MD, Cui B, Roy E, Gauvin R, Giasson CJ, Esch MB, Carrier P, Deschambeault A, Dumoulin M, Toner M, Germain L, Veres T, Auger FA The organization of cells and extracellular matrix (ECM) in native tissues plays a crucial role in their functionality. However, in tissue engineering, cells and ECM are randomly distributed within a scaffold. Thus, the production of engineered-tissue with complex 3D organization remains a challenge. In the present study, we used contact guidance to control the interactions between the material topography, the cells and the ECM for three different tissues, namely vascular media, corneal stroma and dermal tissue. Using a specific surface topography on an elastomeric material, we observed the orientation of a first cell layer along the patterns in the material. Orientation of the first cell layer translates into a physical cue that induces the second cell layer to follow a physiologically consistent orientation mimicking the structure of the native tissue. Furthermore, secreted ECM followed cell orientation in every layer, resulting in an oriented self-assembled tissue sheet. These self-assembled tissue sheets were then used to create 3 different structured engineered-tissue: cornea, vascular media and dermis. We showed that functionality of such structured engineered-tissue was increased when compared to the same non-structured tissue. Dermal tissues were used as a negative control in response to surface topography since native dermal fibroblasts are not preferentially oriented in vivo. Non-structured surfaces were also used to produce randomly oriented tissue sheets to evaluate the impact of tissue orientation on functional output. This novel approach for the production of more complex 3D tissues would be useful for clinical purposes and for in vitro physiological tissue model to better understand long standing questions in biology. PMID: 20023803 [PubMed - as supplied by publisher] |
| The evolution of chemotaxis assays from static models to physiologically relevant platforms.
December 22, 2009 at 8:49 am
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| | The evolution of chemotaxis assays from static models to physiologically relevant platforms. Integr Biol (Camb). 2009 Feb;1(2):170-181 Authors: Toetsch S, Olwell P, Prina-Mello A, Volkov Y The role of chemotactic gradients in the immunological response is an area which elicits a lot of attention due to its impact on the outcome of the inflammatory process. Consequently there are numerous standard in vitro designs which attempt to mimic chemotactic gradients, albeit in static conditions, and with no control over the concentration of the chemokine gradient. In recent times the design of the standard chemotaxis assay has incorporated modern microfluidic platforms, computer controlled flow devices and cell tracking software. Assays under fluid flow which use biochips have provided data which highlight the importance of shear stress on cell attachment and migration towards a chemokine gradient. However, the in vivo environment is far more complex in comparison to conventional cell assay chambers. The designs of biochips are therefore in constant flux as advances in technology permit ever greater imitations of in vivo conditions. Researchers are focused on designing a generation of new biochips and enhancing the physiological relevance of the current assays. The challenge is to combine a shear flow with a 3D scaffold containing the endothelial layer and permitting a natural diffusion of chemokines through a tissue-like basal matrix. Here we review the latest range of chemotaxis assays and assess the innovative features of their designs which enable them to better imitate the in vivo environment. We also present some alternative designs that were initially employed in tissue engineering which could potentially be used in the establishment of novel chemotaxis assays. PMID: 20023801 [PubMed - as supplied by publisher] |
| Directing hepatic differentiation of embryonic stem cells with protein microarray-based co-cultures.
December 22, 2009 at 8:49 am
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| | Directing hepatic differentiation of embryonic stem cells with protein microarray-based co-cultures. Integr Biol (Camb). 2009 Jul;1(7):460-468 Authors: Lee JY, Tuleuova N, Jones CN, Ramanculov E, Zern MA, Revzin A Embryonic stem cells hold considerable promise in tissue engineering and regenerative medicine as a source of tissue-specific cells. However, realizing this promise requires novel methods for guiding lineage-specific differentiation of stem cells. In this study, we developed a micropatterned co-culture platform for stimulating hepatic differentiation of mouse embryonic stem cells (mESCs). Studies of mESC and hepatic cell adhesion preferences revealed that mESCs required fibronectin for attachment, while hepatic cells (HepG2) preferred collagen (I) substrate and did not adhere to fibronectin. Printing columns of collagen (I) and fibronectin spots (300 mum diameter), followed by sequential seeding of the two cell types, allowed the positioning of clusters of mESCs adjacent to groups of hepatic cells within the same microarray. These micropatterned co-cultures were maintained for up to two weeks in hepatic differentiation media supplemented. To examine the differentiation, mESCs were selectively extracted from the co-culture using laser microdissection and analyzed using real-time reverse transcriptase (RT)-polymerase chain reaction (PCR). These analyses revealed that mESCs co-cultured with HepG2 cells showed a decrease in pluripotency gene expression concomitant with up-regulation of endodermal genes. In addition, the co-culture format induced a significant increase in the expression of liver genes compared to mESCs cultured alone. In conclusion, micropatterned co-cultures of mESCs and hepatic cells showed a significant promise in driving stem cell differentiation towards hepatic phenotype. In the future, this cell culture platform will be further enhanced to enable efficient conversion of mouse and human ESCs to hepatocytes. PMID: 20023756 [PubMed - as supplied by publisher] |
| Integration column: Biofunctional polymeric nanoparticles for spatio-temporal control of drug delivery and biomedical applications.
December 22, 2009 at 8:49 am
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| | Integration column: Biofunctional polymeric nanoparticles for spatio-temporal control of drug delivery and biomedical applications. Integr Biol (Camb). 2009 Jul;1(7):446-451 Authors: Rothenfluh DA, Hubbell JA Polymeric nanoparticle technology has evolved from drug carrier design to advanced multifunctional macromolecular structures. They enable drug delivery and release of a bioactive under spatio-temporal control rather than just passive release by a long-circulating carrier. As such, the carrier is enabling the biomolecule or the bioactive to carry out its designed biological function. Due to their small size nanoparticles may also induce perturbations of biological systems different from any other biomaterials, therefore opening up new biomedical applications as well as raising concerns about adverse effects. PMID: 20023754 [PubMed - as supplied by publisher] |
| Bio-electrospraying embryonic stem cells: interrogating cellular viability and pluripotency.
December 22, 2009 at 8:49 am
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| | Bio-electrospraying embryonic stem cells: interrogating cellular viability and pluripotency. Integr Biol (Camb). 2009 Mar;1(3):260-266 Authors: Abeyewickreme A, Kwok A, McEwan JR, Jayasinghe SN Bio-electrospraying, a recently discovered, direct electric field driven cell engineering process, has been demonstrated to have no harmful effects on treated cells at a molecular level. Although several cell types from both immortalized and primary cultures have been assessed post-treatment as a function of time in comparison to controls, the protocol has yet to be applied on embryonic stem cells. This is most important if bio-electrosprays are to further their applicability, in particular with regard to tissue engineering and regenerative medicine, where embryonic stem cells play a fundamental role. In the study presented herein the chosen stem cells are mouse embryonic stem (ES) cells. Hence, these first examples where embryonic stem cells have been jetted by way of bio-electrosprays, demonstrate the cellular viability and the cell's pluripotency indistinguishable when comparing those post-treated cells with their respective controls. PMID: 20023737 [PubMed - as supplied by publisher] |
| Tissue engineering of skin.
December 22, 2009 at 8:49 am
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| | Tissue engineering of skin. Burns. 2009 Dec 18; Authors: Böttcher-Haberzeth S, Biedermann T, Reichmann E The engineering of skin substitutes and their application on human patients has become a reality. However, cell biologists, biochemists, technical engineers, and surgeons are still struggling with the generation of complex skin substitutes that can readily be transplanted in large quantities, possibly in only one surgical intervention and without significant scarring. Constructing a dermo-epidermal substitute that rapidly vascularizes, optimally supports a stratifying epidermal graft on a biodegradable matrix, and that can be conveniently handled by the surgeon, is now the ambitious goal. After all, this goal has to be reached coping with strict safety requirements and the harsh rules of the economic market. PMID: 20022702 [PubMed - as supplied by publisher] |
| In vitro engineering of human ear-shaped cartilage assisted with CAD/CAM technology.
December 22, 2009 at 8:49 am
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| | In vitro engineering of human ear-shaped cartilage assisted with CAD/CAM technology. Biomaterials. 2009 Dec 17; Authors: Liu Y, Zhang L, Zhou G, Li Q, Liu W, Yu Z, Luo X, Jiang T, Zhang W, Cao Y Due to the lack of appropriate scaffolds, the in vitro engineering of cartilage tissue with a sophisticated structure, such as a human ear, remains a great challenge. Although polyglycolic acid (PGA) has become one of the most successful scaffolds for cartilage regeneration, how to overcome its limitations in achieving desirable mechanical strength and accurate control over shape remains an unsolved problem. In this study, the mechanical strength of PGA scaffold was enhanced by coating with polylactic acid (PLA). The content of PLA was optimized by balancing the scaffold's biocompatibility and mechanical strength. The PLA/PGA scaffold was then fabricated into a human ear-shape mirror-symmetrical to a normal ear by pressing the scaffold in the ear negative molds, which were fabricated by the computer aided design and manufacturing (CAD/CAM) technique according to the CT scan data from the normal ear. The ear-shaped scaffold reached a similarity level of over 97% compared to the positive ear mold by the shape analysis using a 3D laser scan system. Most importantly, after chondrocyte seeding, the constructs largely retained the original shape during culture with a similarity level of over 84%. Furthermore, the constructs formed ear-shaped cartilage-like tissues at 12 weeks, which revealed a tissue structure with abundant cartilage extracellular matrices and mature lacuna. Additionally, the ear-shaped cartilage at 12 weeks also exhibited fine elasticity and good mechanical strength. These results may provide a useful strategy for reconstructing cartilage tissue with complicated shapes such as a human ear by an in vitro engineering approach. PMID: 20022366 [PubMed - as supplied by publisher] |
| Effect of surface modification on the in vitro calcium phosphate growth on the surface of poly(methyl methacrylate) and bioactivity.
December 22, 2009 at 8:49 am
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| | Effect of surface modification on the in vitro calcium phosphate growth on the surface of poly(methyl methacrylate) and bioactivity. Colloids Surf B Biointerfaces. 2009 Nov 20; Authors: Choi SM, Yang WK, Yoo YW, Lee WK Poly(methyl methacrylate) (PMMA) is a biocompatible polymer widely used for bone substitutes. Its surface properties, however, are not favorable for the induction of biological apatite which can be directly related to natural bone formation. In this study, the surface of PMMA was modified by NaOH treatment or sequential treatments with ethanol (EtOH) and NaOH. Results displayed that surface hydrophilicity was improved for increasing treatment time and NaOH concentration. Field-emission scanning electron microscope (FE-SEM) displayed that in vitro formation of calcium phosphate (CaP) coating was significantly promoted by the surface modifications. X-ray photon spectroscopy (XPS) examination elucidated that the films prepared on PMMA consisted of calcium and phosphorus and their values for Ca/P ratio were closed to octacalcium phosphate (OCP). Fourier transform infrared (FT-IR) spectra of the film coated on PMMA revealed a band characteristic of phosphate groups confirming that CaP films were formed and their characteristics were dependent on the surface properties of PMMA. Cellular assay demonstrated that the adhesion of osteoblast-like MG63 cells was significantly promoted on CaP-coated PMMA. Proliferation assay showed that CaP films appeared not to exert any cytotoxic effects on the growth of MG63 cells. PMID: 20022226 [PubMed - as supplied by publisher] |
| Bladder Dysfunction in a New Mutant Mouse Model With Increased Superoxide-Lack of Nitric Oxide?
December 22, 2009 at 8:49 am
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| | Bladder Dysfunction in a New Mutant Mouse Model With Increased Superoxide-Lack of Nitric Oxide? J Urol. 2009 Dec 16; Authors: Soler R, Füllhase C, Lu B, Bishop CE, Andersson KE PURPOSE: Nitric oxide mediates urethral smooth muscle relaxation and may also be involved in detrusor activity control. Mice with mutation in the Immp2l gene have high superoxide ion levels and a consequent decrease in the bioavailable amount of nitric oxide. We studied bladder function in this mouse model. MATERIAL AND METHODS: Young male mutants at ages 4 to 6 months, old female mutants at age 18 months and healthy WT age matched controls were used. The detrusor contractile response to carbachol and electrical field stimulation was tested in isolated detrusor strips in organ baths. In vivo bladder function was evaluated by cystometry in conscious animals. RESULTS: Young male mutants had significantly lower micturition and higher post-void residual volume than WT controls. They had pronounced voiding difficulty and strained when initiating micturition. Detrusor contractile responses to carbachol and electrical field stimulation were similar in mutant and WT mice. Old female mutant mice had lower bladder capacity and micturition volume, and higher micturition frequency and bladder-to-body weight ratio than WT controls. In the in vitro study detrusor strips from mutants showed a lower maximum response to carbachol. CONCLUSIONS: Mice with mutation in the Immp2l gene have bladder dysfunction, mainly characterized by emptying abnormalities in young males and increased detrusor activity in old females. Detrusor function was preserved in young males and impaired in old females. These animals are a natural model of oxidative stress with low bioavailable nitric oxide. Thus, they are interesting tools in which to evaluate the role of these conditions on bladder dysfunction. PMID: 20022053 [PubMed - as supplied by publisher] |
| [Improve efficacy of stem cell therapy for coronary heart diseases: choosing "seed cells"]
December 22, 2009 at 8:49 am
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| | [Improve efficacy of stem cell therapy for coronary heart diseases: choosing "seed cells"] Zhonghua Xin Xue Guan Bing Za Zhi. 2009 Aug;37(8):675-9 Authors: Huang RC, Ge JB PMID: 20021916 [PubMed - in process] |
| Differentiation of Human Bone Marrow Mesenchymal Stem Cells into Bladder Cells: Potential for Urological Tissue Engineering.
December 22, 2009 at 8:49 am
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| | Differentiation of Human Bone Marrow Mesenchymal Stem Cells into Bladder Cells: Potential for Urological Tissue Engineering. Tissue Eng Part A. 2009 Dec 18; Authors: Tian H, Bharadwaj S, Liu Y, Ma PX, Atala A, Zhang Y Bone marrow mesenchymal stem cells (BMSC) are capable of differentiating into multiple cell types, providing an alternative cell source for cell-based therapy and tissue engineering. Simultaneously differentiating human BMSC into smooth muscle cell (SMC) and urothelium would be beneficial for clinical applications in bladder regeneration for patients with bladder exstrophy or cancer who need cystoplasty. We investigated the ability of human BMSC to differentiate towards both SMC and urothelium with co-cultured or conditional media and analyzed growth factors from a co-culture system. After being co-cultured with urothelium or cultured using urothelium-derived conditioned medium, human BMSC expressed urothelium-specific genes and proteins: uroplakin-Ia, cytokeratin-7 and cytokeratin-13. When co-cultured with SMC or cultured in SMC-conditioned medium, human BMSC expressed SMC-specific genes and proteins: desmin and myosin. Several growth factors (HGF, PDGF-BB, TGF- beta1 and VEGF) were detected in the SMC co-cultured media and in the urothelium co-cultured media (EGF, PDGF-BB, TGF-beta1 and VEGF). BMSC-scaffold constructs significantly improved cell contractility after myogenic differentiation. In vivo grafted cells displayed significant matrix infiltration and expressed SMC-specific markers in the nano-fibrous PLLA scaffolds. In conclusions, smooth muscle- and urothelium-like cells derived from human BMSC provide an alternative cell source for potential use in bladder tissue engineering. PMID: 20020816 [PubMed - as supplied by publisher] |
| Bonelike Apatite Formation Utilizing Carbon Nanotubes as Template.
December 22, 2009 at 8:49 am
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| | Bonelike Apatite Formation Utilizing Carbon Nanotubes as Template. Langmuir. 2009 Dec 18; Authors: Niu L, Kua H, Chua DH Template-induced hydroxyapatite (HA) has broad prospects in the applied fields of regenerative medicine and bone repair. HA thin coatings have been deposited on vertically aligned multiwalled carbon nanotubes (CNTs) via the high-temperature radio-frequency (rf) magnetron sputtering deposition technique. Simulated body fluid (SBF) solution has been used to soak and incubate the HA/CNTs nanocomposites at 37 degrees C. SEM, EDS, XRD, and FTIR characterizations revealed bonelike apatite formation on top of HA/CNTs composites. Coating HA material on well-aligned CNT-template provides a way of combining the superior mechanical properties and chemical stability of the CNTs with the excellent biochemical properties of HA. PMID: 20020722 [PubMed - as supplied by publisher] | 
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