|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Surgical approaches to gene and stem cell therapy for retinal disease. Hum Gene Ther. 2011 Apr 11; Authors: Stout T As pointed out in the articles in this special issue, the eye presents a unique opportunity to study the delivery of therapeutic genetic material. There are many factors that make ocular gene therapy attractive and successful: i) Almost all of the structures of the eye are visible and can be examined in the clinic at the slit lamp - treatment response and potential complications can be visualized in real time. ii) A wide variety of objective, non-invasive imaging and functional assessment modalities have been developed to evaluate visual function. iii) Almost all of the structures of the eye are surgically approachable via minimally invasive procedures that are performed in the outpatient setting under local anesthesia. iv) The eye is relatively immunoprivileged with a robust blood-retinal barrier and essentially no lymphatic system. v) The eye is a compact organ that requires relatively small volumes and doses of therapeutic agents and, finally, vi) the vision loss associated with many ophthalmic diseases are symptomatic at stages that are amenable to intervention. PMID: 21480778 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | High-mobility group protein HMGA2-derived fragments stimulate the proliferation of chondrocytes and adipose tissue-derived stem cells. Eur Cell Mater. 2011;21:355-63 Authors: Richter A, Lübbing M, Frank HG, Nolte I, Bullerdiek JC, von Ahsen I In previous research, it was shown that recombinant HMGA2 protein enhances the proliferation of porcine chondrocytes grown in vitro, opening up promising applications of this embryonic architectural transcription factor for tissue engineering, such as in cartilage repair. In this paper, we describe the development and analyses of two synthetic fragments comprising the functional AT-hook motifs of the HMGA2 protein, as well as the nuclear transport domain. They can be synthesised up to large scales, while eliminating some of the problems of recombinant protein production, including unwanted modification or contamination by the expression hosts, or of gene therapy approaches such as uncontrolled viral integration and transgene expression even after therapy. Application of one of these peptides onto porcine hyaline cartilage chondrocytes, grown in in vitro monolayer cell culture, showed a growth-promoting effect similar to that of the wild type HMGA2 protein. Furthermore, it also promoted cell growth of adult adipose tissue derived stem cells. Due to its proliferation inducing function and vast availability, this peptide is thus suitable for further application and investigation in various fields such as tissue engineering and stem cell research. PMID: 21484705 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Texture analysis of TEM micrographs of alginate gels for cell microencapsulation. Microsc Res Tech. 2011 Jan;74(1):58-66 Authors: Brun F, Accardo A, Marchini M, Ortolani F, Turco G, Paoletti S In this work, the morphological characteristics of a calcium alginate gel and a binary (gel) mixture composed of (calcium) alginate and lactose-modified chitosan (chitlac) are evaluated and compared to quantify the differences between the two three-dimensional (3D) structures. A set of textural descriptors based on histogram analysis as well as on gray level co-occurrence matrix and on fractal dimension is extracted from transmission electron microscopy micrographs to describe the morphological differences that the images present. The obtained results reveal significant quantitative morphological differences between the calcium alginate gel and the binary gel mixture that were already inferred from rheological experiments, so as to provide a structural basis for developing new encapsulation systems based on such mixed polymer gels. PMID: 21181711 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Magnetic resonance imaging tracking of human adipose derived stromal cells within three-dimensional scaffolds for bone tissue engineering. Eur Cell Mater. 2011;21:341-54 Authors: Lalande C, Miraux S, Derkaoui SM, Mornet S, Bareille R, Fricain JC, Franconi JM, Le Visage C, Letourneur D, Amédée J, Bouzier-Sore AK For bone tissue engineering, human Adipose Derived Stem Cells (hADSCs) are proposed to be associated with a scaffold for promoting bone regeneration. After implantation, cellularised scaffolds require a non-invasive method for monitoring their fate in vivo. The purpose of this study was to use Magnetic Resonance Imaging (MRI)-based tracking of these cells, labelled with magnetic agents for in vivo longitudinal assessment. hADSCs were isolated from adipose tissue and labelled with USPIO-rhodamine (Ultrasmall SuperParamagnetic Iron Oxide). USPIO internalisation, absence of toxicity towards hADSCs, and osteogenic differentiation of the labelled cells were evaluated in standard culture conditions. Labelled cells were then seeded within a 3D porous polysaccharide-based scaffold and imaged in vitro using fluorescence microscopy and MRI. Cellularised scaffolds were implanted subcutaneously in nude mice and MRI analyses were performed from 1 to 28 d after implantation. In vitro, no effect of USPIO labelling on cell viability and osteogenic differentiation was found. USPIO were efficiently internalised by hADSCs and generated a high T2* contrast. In vivo MRI revealed that hADSCs remain detectable until 28 d after implantation and could migrate from the scaffold and colonise the area around it. These data suggested that this scaffold might behave as a cell carrier capable of both holding a cell fraction and delivering cells to the site of implantation. In addition, the present findings evidenced that MRI is a reliable technique to validate cell-seeding procedures in 3D porous scaffolds, and to assess the fate of hADSCs transplanted in vivo. PMID: 21484704 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Human dental pulp progenitor cell behavior on aqueous and hexafluoroisopropanol based silk scaffolds. J Biomed Mater Res A. 2011 Apr 11; Authors: Zhang W, Ahluwalia IP, Literman R, Kaplan DL, Yelick PC Silk scaffolds have been successfully used for a variety of tissue engineering applications due to their biocompatibility, diverse physical characteristics, and ability to support cell attachment and proliferation. Our prior characterization of 4-day postnatal rat tooth bud cells grown on hexafluoro-2-propanol (HFIP) silk scaffolds showed that the silk scaffolds not only supported osteodentin formation, but also guided the size and shape of the formed osteodentin. In this study, interactions between human dental pulp cells and HFIP and aqueous based silk scaffolds were studied under both in vitro and in vivo conditions. Silk scaffold porosity and incorporation of RGD and DMP peptides were examined. We found that the degradation of aqueous based silk is much faster than HFIP based silk scaffolds. Also, HFIP based silk scaffolds supported the soft dental pulp formation better than the aqueous based silk scaffolds. No distinct hard tissue regeneration was found in any of the implants, with or without additional cells. We conclude that alternative silk scaffold materials, and hDSC pre-seeding cell treatments or sorting and enrichment methods, need to be considered for successful dental hard tissue regeneration. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 2011. PMID: 21484985 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The Influence of Patterned Nanofiber Meshes on Human Mesenchymal Stem Cell Osteogenesis. Macromol Biosci. 2011 Apr 11; Authors: Martins A, Alves da Silva ML, Faria S, Marques AP, Reis RL, Neves NM A specially designed electroconductive collector enables the electrospinning of P-NFM composed of areas of parallel/uniaxially aligned fibers and areas of random/orthogonal nanofiber distribution. The biological relevance of P-NFM is demonstrated using hBMSCs as an autologous cell source. The structures induce cell orientation along the uniaxially aligned fibers, mainly during earlier culturing periods under basal and osteogenic differentiation conditions. The microtopography of the P-NFM also controls the deposition of mineralized extracellular matrix along the pre-defined fiber direction. Genotypic characterization confirms the successful differentiation into the osteogenic lineage. PMID: 21485007 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Quantification of the forces driving self-assembly of three-dimensional microtissues. Proc Natl Acad Sci U S A. 2011 Apr 11; Authors: Youssef J, Nurse AK, Freund LB, Morgan JR In a nonadhesive environment, cells will self-assemble into microtissues, a process relevant to tissue engineering. Although this has been recognized for some time, there is no basis for quantitative characterization of this complex process. Here we describe a recently developed assay designed to quantify aspects of the process and discuss its application in comparing behaviors between cell types. Cells were seeded in nonadhesive micromolded wells, each well with a circular trough at its base formed by the cylindrical sidewalls and by a central peg in the form of a right circular cone. Cells settled into the trough and coalesced into a toroid, which was then driven up the conical peg by the forces of self-assembly. The mass of the toroid and its rate of upward movement were used to calculate the cell power expended in the process against gravity. The power of the toroid was found to be 0.31 ± 0.01 pJ/h and 4.3 ± 1.7 pJ/h for hepatocyte cells and fibroblasts, respectively. Blocking Rho kinase by means of Y-27632 resulted in a 50% and greater reduction in power expended by each type of toroid, indicating that cytoskeletal-mediated contraction plays a significant role in the self-assembly of both cell types. Whereas the driving force for self-assembly has often been viewed as the binding of surface proteins, these data show that cellular contraction is important for cell-cell adhesion. The power measurement quantifies the contribution of cell contraction, and will be useful for understanding the concerted action of the mechanisms that drive self-assembly. PMID: 21482784 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Hes1 is required for contact inhibition of cell proliferation in 3T3-L1 preadipocytes. Genes Cells. 2011 Apr 12; Authors: Noda N, Honma S, Ohmiya Y Cell-cell contact causes the growth arrest of cells in culture, which is referred to as contact inhibition of cell proliferation. Notch signaling is involved in the growth arrest of cells represented by contact inhibition of cell proliferation. The Notch effector, Hes1 (Hairy and enhancer of split 1), promotes or inhibits cell proliferation by repressing the expression of cyclin-dependent kinase inhibitors. However, it is still unclear whether Hes1 is involved in the mechanisms responsible for contact inhibition of cell proliferation. Here, we examined the involvement of Hes1 in contact inhibition of cell proliferation using a γ-secretase inhibitor and a stable 3T3-L1 preadipocyte cell line expressing Hes1-shRNA as a model cell. The cell cycle was not arrested in Hes1-knockdown cells even after the cells reached confluence. Reduced Hes1 levels failed to repress the expression of E2F-1, a transcription factor required for the progression of the cell cycle. The expression of Myc, cyclin E1, and cyclin A2 in E2F-1 target genes was also higher in Hes1-knockdown cells compared with the negative control. These results suggest that Hes1 plays essential roles in contact inhibition of cell proliferation in 3T3-L1 cells by repressing E2F-1 expression. PMID: 21481105 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Progress on the molecular mechanism and research methods of the interaction between cell and silk fibroin material]. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2011 Feb;28(1):189-94 Authors: Qin B, Zhao D This paper took silk fibroin material as an example to explain the effect of a variety of physical and chemical properties of the silk material on cell adhesion and reviewed the molecular mechanism between cell and materials in tissue engineering in recent years. According to this, the present paper outlines a set of research systems to explore the interaction between cell and material in tissue engineering. PMID: 21485211 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | A saccharide-based supramolecular hydrogel for cell culture. Carbohydr Res. 2011 Mar 23; Authors: Wang W, Wang H, Ren C, Wang J, Tan M, Shen J, Yang Z, Wang PG, Wang L It is well known that the saccharides forming the intricate sugar coat that surrounds the cells play important biological roles in intercellular communication and cell differentiation. Therefore, it is worthwhile developing saccharide-based hydrogels for cell culture study. In this study, three novel saccharide-based compounds were designed and synthesized. It was found that one of them could form hydrogels efficiently, while the other two precipitated from water. The stability of the resulting hydrogel was tested, and the supramolecular nanofiber with fiber diameters in the range of 80-300nm was characterized as the structural element by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fluorescence microscopy revealed that extensive hydrogen bonds between sugar rings assisted the formation of efficient π-π stacking between aromatic naphthalene groups, thus resulting in the formation of a stable hydrogel in aqueous solution. When the gel was applied for mouse embryonic fibroblast (NIH 3T3), human hepatocellular carcinoma (HepG2), AD293 and HeLa cells culture in two dimensional environments, all of them showed a very good adhesion and good proliferation rate on the top of the hydrogel. These results indicates that the biocompatible hydrogel reported here has a potential to be developed into useful materials for in vitro cell culture, drug delivery, and tissue engineering. PMID: 21482421 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Heparin-conjugated scaffolds with pore structure of inverted colloidal crystals for cartilage regeneration. Colloids Surf B Biointerfaces. 2011 Feb 1;82(2):616-23 Authors: Kuo YC, Tsai YT A uniform de novo production of neocartilage is a critical issue in the fabrication of tissue-engineered diarthrodial substitutes. The aim of this work is to develop homogeneous chondrogenesis in heparinized scaffolds with pores of inverted colloidal crystal (ICC) geometry. Monodispersed polystyrene microspheres were self-assembled by floating in the medium containing ethylene glycol, dried, annealed and infiltrated with heparin/chitin/chitosan gels. The results indicated that the colloidal template was in a structure of hexagonal arrays. In addition, the regularity of the organized pores in the scaffolds reduced when the concentration of ethylene glycol decreased. An increase in the weight percentage of heparin enhanced the viability of bovine knee chondrocytes (BKCs) in ICC matrices. Over 4 weeks of cultivation, the amount of cartilaginous components including BKCs, glycosaminoglycans (GAGs) and collagen enhanced with time. Moreover, an increase in the weight percentage of heparin promoted the production of BKCs, GAGs and collagen in ICC constructs. Histological and immunochemical staining of the cultured ICC constructs revealed minor differences in BKCs, GAGs and type II collagen between the peripheral and core regions. Therefore, the ordered pores in the heparinized ICC constructs could favor the chondrocyte culture to regenerate a uniform distribution of cartilage. PMID: 21074384 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The therapeutic potential of engineered human neovessels for cell-based gene therapy. Expert Opin Biol Ther. 2011 Jan;11(1):67-76 Authors: Alvarez-Vallina L, Sanz L Importance of the field: Several works have shown the feasibility of engineering functional blood vessels in vivo using human endothelial cells and mural cells. In this context, the genetic modification of endothelial cells would ensure the secretion of a therapeutic protein into the systemic circulation for a prolonged period of time. Areas covered in this review: We discuss the different strategies aimed at the formation of long-lasting neovessels in vivo, using human endothelial and mural cells. The main focus is the potential of these constructs in gene therapy strategies for the in vivo production of therapeutic proteins. What the reader will gain: The reader will have an outline of the different types of cells that have been used for microvessel engineering in vivo, as well as scaffolds employed to seed these cells. We provide a critical review of their advantages and drawbacks, along with examples of their potential in cell-based gene therapy strategies. Take home message: There is a real potential for neovessels derived from human endothelial and mural cells to be incorporated in clinical interventions, either as a cell-based gene therapy to produce a therapeutic protein or as a component of engineered tissue constructs in regenerative medicine. PMID: 21080857 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Encapsulation of eukaryotic cells in alginate microparticles: cell signaling by TNF-alpha through capsular structure of cystic fibrosis cells. J Cell Commun Signal. 2010 Nov 25; Authors: Mazzitelli S, Borgatti M, Breveglieri G, Gambari R, Nastruzzi C Entrapment of mammalian cells in natural or synthetic biomaterials represents an important tool for both basic and applied research in tissue engineering. For instance, the encapsulation procedures allow to physically isolate cells from the surrounding environment, after their transplantation maintaining the normal cellular physiology. The first part of the current paper describes different microencapsulation techniques including bulk emulsion technique, vibrating-nozzle procedure, gas driven mono-jet device protocol and microfluidic based approach. In the second part, the application of a microencapsulation procedure to the embedding of IB3-1 cells is also described. IB3-1 is a bronchial epithelial cell line, derived from a cystic fibrosis (CF) patient. Different experimental parameters of the encapsulation process were analyzed, including frequency and amplitude of vibration, polymer pumping rate and distance between the nozzle and the gelling bath. We have found that the microencapsulation procedure does not alter the viability of the encapsulated IB3-1 cells. The encapsulated IB3-1 cells were characterized in term of protein secretion, analysing the culture medium by Bio-Plex strategy. The analyzed factors include members of the interleukin family (IL-6), chemokines (IL-8 and MCP-1) and growth factors (G-CSF). The experiments demonstrated that most of the analyzed proteins, were secreted both by the free and encapsulated cells, even if in a different extent. PMID: 21484183 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Activation of cyclic amp/protein kinase: a signaling pathway enhances osteoblast cell adhesion on biomaterials for regenerative engineering. J Orthop Res. 2011 Apr;29(4):602-8 Authors: Lo KW, Ashe KM, Kan HM, Lee DA, Laurencin CT Osteoblast cell adhesion on biomaterials is an important goal for implants to be useful in bone regeneration technologies. The adhesion of osteoblastic cells to biomaterials has been investigated in the field of bone regenerative engineering. Previous work from our group demonstrated that osteoblastic cells adhering to biodegradable biomaterials require the expression of integrins on the cell surface. However, the underlying molecular signaling mechanism is still not fully clear. We report here that cyclic adenosine monophosphate (cAMP), a small signaling molecule, regulates osteoblast cell adhesion to biomaterial surfaces. We used an in vitro cell adhesion assay to demonstrate that at 0.1 mM, 8-Br-cAMP, a cell-permeable cAMP analog, significantly enhances osteoblast-like cells' (MC3T3-E1) adherence to biomaterials. Moreover, we demonstrate that a commonly used cAMP-elevating agent, forskolin, promotes cell adhesion similar to that of the cell permeable cAMP analog. By using different target-specific cAMP analogs: 8-CPT-2Me-cAMP which specifically activates exchange protein activated by cAMP (Epac), and 6-Bnz-cAMP which specifically activates protein kinase A (PKA), we observed that the PKA signaling pathway plays a dominant role in this process. Thus, this report suggests a new method to enhance osteoblast cell adhesion on biodegradable biomaterials for bone regenerative engineering applications. PMID: 20957743 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Formation of tissue engineered composite construct of cartilage and skin using high density polyethylene as inner scaffold in the shape of human helix. Int J Pediatr Otorhinolaryngol. 2011 Apr 8; Authors: Ruszymah BH, Chua KH, Mazlyzam AL, Aminuddin BS BACKGROUND: Formation of external ear via tissue engineering has created interest amongst surgeons as an alternative for ear reconstruction in congenital microtia. OBJECTIVE: To reconstruct a composite human construct of cartilage and skin in the shape of human ear helix in athymic mice. METHODS: Six human nasal cartilages were used and digested with Collagenase II. Chondrocytes were passaged in 175cm(2) culture flasks at a density of 10,000cells/cm(2). Frozen human plasma was then mixed with human chondrocytes. Six human skin samples were cut into small pieces trypsinized and resuspended. The keratinocytes were plated in six-well plate culture dishes at a density of 2×105 cells per well. Dermis tissues were digested and the fibroblast cells resuspended in six-well plate at the density of 10,000 cells per well. Fibrin-fibroblast layer and fibrin-keratinocytes were formed by mixing with human plasma to create 6 bilayered human skin equivalent (BSE) constructs. The admixture of fibrin chondrocytes layers was wrapped around high density polyethylene (HDP), and implanted at the dorsum of the athymic mice. The construct was left for 4 weeks and after maturation the mice skin above the implanted construct was removed and replaced by BSE for another 4 weeks. RESULTS: Haematoxylin and Eosin showed that the construct consists of fine arrangement and organized tissue structure starting with HDP followed by cartilage, dermis and epidermis. Safranin-O staining was positive for proteoglycan matrix production. Monoclonal mouse antihuman cytokeratin, 34βE12 staining displayed positive result for human keratin protein. CONCLUSIONS: The study has shown the possibility to reconstruct ear helix with HDP and tissue engineered human cartilage and skin. This is another step to form a human ear and hopefully will be an alternative in reconstructive ear surgery. PMID: 21481479 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | siRNA therapy for cancer and non-lethal diseases such as arthritis and osteoporosis. Expert Opin Biol Ther. 2011 Jan;11(1):5-16 Authors: Shi Q, Zhang XL, Dai KR, Benderdour M, Fernandes JC Gene silencing mediated by siRNA has been widely investigated as a potential therapeutic approach. The success of these therapies depends on effective systems capable of selectively and efficiently conveying siRNA to targeted cells/organs with minimal toxicity. PMID: 21058934 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Engineered tissue scaffolds with variational porous architecture. J Biomech Eng. 2011 Jan;133(1):011001 Authors: Khoda AK, Ozbolat IT, Koc B This paper presents a novel computer-aided modeling of 3D tissue scaffolds with a controlled internal architecture. The complex internal architecture of scaffolds is biomimetically modeled with controlled micro-architecture to satisfy different and sometimes conflicting functional requirements. A functionally gradient porosity function is used to vary the porosity of the designed scaffolds spatially to mimic the functionality of tissues or organs. The three-dimensional porous structures of the scaffold are geometrically partition into functionally uniform porosity regions with a novel offsetting operation technique described in this paper. After determining the functionally uniform porous regions, an optimized deposition-path planning is presented to generate the variational internal porosity architecture with enhanced control of interconnected channel networks and continuous filament deposition. The presented methods are implemented, and illustrative examples are presented in this paper. Moreover, a sample optimized tool path for each example is fabricated layer-by-layer using a micronozzle biomaterial deposition system. PMID: 21186891 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | High-mobility group protein HMGA2-derived fragments stimulate the proliferation of chondrocytes and adipose tissue-derived stem cells. Eur Cell Mater. 2011;21:355-63 Authors: Richter A, Lübbing M, Frank HG, Nolte I, Bullerdiek JC, von Ahsen I In previous research, it was shown that recombinant HMGA2 protein enhances the proliferation of porcine chondrocytes grown in vitro, opening up promising applications of this embryonic architectural transcription factor for tissue engineering, such as in cartilage repair. In this paper, we describe the development and analyses of two synthetic fragments comprising the functional AT-hook motifs of the HMGA2 protein, as well as the nuclear transport domain. They can be synthesised up to large scales, while eliminating some of the problems of recombinant protein production, including unwanted modification or contamination by the expression hosts, or of gene therapy approaches such as uncontrolled viral integration and transgene expression even after therapy. Application of one of these peptides onto porcine hyaline cartilage chondrocytes, grown in in vitro monolayer cell culture, showed a growth-promoting effect similar to that of the wild type HMGA2 protein. Furthermore, it also promoted cell growth of adult adipose tissue derived stem cells. Due to its proliferation inducing function and vast availability, this peptide is thus suitable for further application and investigation in various fields such as tissue engineering and stem cell research. PMID: 21484705 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The reconstructed skin micronucleus assay (RSMN) in EpiDerm™: detailed protocol and harmonized scoring atlas. Mutat Res. 2011 Feb 28;720(1-2):42-52 Authors: Dahl EL, Curren R, Barnett BC, Khambatta Z, Reisinger K, Ouedraogo G, Faquet B, Ginestet AC, Mun G, Hewitt NJ, Carr G, Pfuhler S, Aardema MJ The European Cosmetic Toiletry and Perfumery Association (COLIPA), along with contributions from the European Centre for the Validation of Alternative Methods (ECVAM), initiated a multi-lab international prevalidation project on the reconstructed skin micronucleus (RSMN) assay in EpiDerm™ for the assessment of the genotoxicity of dermally applied chemicals. The first step of this project was to standardize the protocol and transfer it to laboratories that had not performed the assay before. Here we describe in detail the protocol for the RSMN assay in EpiDerm™ and the harmonized guidelines for scoring, with an atlas of cell images. We also describe factors that can influence the performance of the assay. Use of these methods will help new laboratories to conduct the assay, thereby further increasing the database for this promising new in vitro genotoxicity test. PMID: 21147256 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | The next step in urethral reconstruction. Lancet. 2011 Apr 2;377(9772):1130-1 Authors: Sievert KD PMID: 21388672 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | [Preliminary evaluation of the biological properties of poly-lactide-co-glycolic acid (PLGA) knitted mesh]. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2011 Feb;28(1):163-9 Authors: Yu W, Wang X, Hu X, Sun H, Han C This is a work aimed to investigate the biodegradability, biocompatibility and mechanical property of the poly-lactide-co-glycolic acid (PLGA) knitted mesh preliminarily and to further explore its applications in tissue engineering and regenerative medicine. The biological property of PLGA mesh was investigated comprehensively with the degradation experiment in vitro, the acute cytotoxicity assay, the intradermal irritation test and the subcutaneous implantation test in vivo utilized. The degradation experiment in vitro demonstrated that the pH value of the removed solution fluctuated between 6.68 and 7.33. The elastic modulus of the PLGA mesh increased at first and then decreased afterwards. The acute toxicity test and the intradermal irritation test indicated that the PLGA mesh was with innocuity safety. The PLGA mesh accelerated degradation and was replaced gradually by the neotissue. The results of immunohistochemical staining demonstrated that the number of ED-1+ cells increased at first and then decreased afterwards. The PLGA mesh with excellent mechanical properties, good biocompatibility and favorable degradation ratio has the potential to be employed as a "skeleton" to reinforce the mechanical property of collagen-based dermal substitutes in tissue engineering. PMID: 21485206 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication of porous beta-tricalcium phosphate with microchannel and customized geometry based on gel-casting and rapid prototyping. Proc Inst Mech Eng H. 2011 Mar;225(3):315-23 Authors: Li X, Bian W, Li D, Lian Q, Jin Z The tissue engineering scaffolds with three-dimensional porous structure are regarded to be beneficial to facilitate a sufficient supply of nutrients and enable cell ingrowth in bone reconstruction. However, the pores in scaffolds tend to be blocked by the cell ingrowth and result in a restraint of nutrient supply in the further side of the scaffold. An indirect approach of combining the rapid prototyping and gel-casting technique is introduced in this study to fabricate beta-tricalcium phosphate (beta-TCP) scaffolds which not only have interconnected porous structure, but also have a microchannel network inside. The scaffold was designed with customized geometry that matches the defect area, and a double-scale (micropores-microchannel) porous structure inside that is beneficial for cell ingrowth. The scaffolds fabricated have an open, uniform, and interconnected porous architecture with a pore size of 200-400 microm, and posses an internal channel network with a diameter of 600 microm. The porosity was controllable. The compressive yield strength was 4.5 MPa with a porosity of 70 per cent. X-ray diffraction analysis shows that these fabrication processes do not change the crystal structure and chemical composition of beta-TCP. With this technique, it was also possible to fabricate porous scaffolds with desired pore size, porosity, and microchannel, as well as customized geometries by other bioceramics. PMID: 21485332 [PubMed - in process] | | | | | | | | | |  | |  | |  |
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