| Centrifugal seeding of mammalian cells in nonwoven fibrous matrices.
September 29, 2009 at 8:38 am
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| | Centrifugal seeding of mammalian cells in nonwoven fibrous matrices. Biotechnol Prog. 2009 Sep 25; Authors: Ng R, Gurm JS, Yang ST Three-dimensional (3D) cell cultures have many advantages over two-dimensional cultures. However, seeding cells in 3D scaffolds such as nonwoven fibrous polyethylene terephthalate (PET) matrices has been a challenge task in tissue engineering and cell culture bioprocessing. In this study, a centrifugal seeding method was investigated to improve the cell seeding efficiency in PET matrices with two different porosities (93% and 88%). Both the centrifugal force and centrifugation time were found to affect the seeding efficiency. With an appropriate centrifugation speed, a high 80-90% cell seeding efficiency was achieved and the time to reach this high seeding efficiency was less than 5 min. The seeding efficiency was similar for matrices with different porosities, although the optimal seeding time was significantly shorter for the low-porosity scaffold. Post seeding cell viability was demonstrated by culturing colon cancer cells seeded in PET matrices for over 5 days. The centrifugal seeding method developed in this work can be used to efficiently and uniformly seed small fibrous scaffolds for applications in 3D cell-based assays for high-throughput screening. (c) 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009. PMID: 19785042 [PubMed - as supplied by publisher] |
| Fabrication and biocompatibility of nano non-stoichiometric apatite and poly(epsilon-caprolactone) composite scaffold by using prototyping controlled process.
September 29, 2009 at 8:38 am
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| | Fabrication and biocompatibility of nano non-stoichiometric apatite and poly(epsilon-caprolactone) composite scaffold by using prototyping controlled process. J Mater Sci Mater Med. 2009 Sep 27; Authors: Ye L, Zeng X, Li H, Ai Y Nano biocomposite scaffolds of non-stoichiometric apatite (ns-AP) and poly(epsilon-caprolactone) (PCL) were prepared by a prototyping controlled process (PCP). The results show that the composite scaffolds with 40 wt% ns-AP contained open and well interconnected pores with a size of 400-500 mum, and exhibited a maximum porosity of 76%. The ns-AP particles were not completely embedded in PCL matrix while exposed on the composite surface, which might be useful for cell attachment and growth. Proliferation of MG(63) cells was significantly better on the composite scaffolds with porosity of 76% than that those with porosity of 53%, indicating that the scaffolds with high porosity facilitated cell growth, and could promote cell proliferation. The composite scaffolds were implanted into rabbit thighbone defects to investigate the in vivo biocompatibility and osteogenesis. Radiological and histological examination confirmed that the new bony tissue had grown easily into the entire composite scaffold. The results suggest that the well-interconnected pores in the scaffolds might encourage cell proliferation, and migration to stimulate cell functions, thus enhancing bone formation in the scaffolds. This study shows that bioactive and biocompatible ns-AP/PCL composite scaffolds have potential applications in bone tissue engineering. PMID: 19784867 [PubMed - as supplied by publisher] |
| Interaction between hepatocytes and collagen gel in hollow fibers.
September 29, 2009 at 8:38 am
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| | Interaction between hepatocytes and collagen gel in hollow fibers. Cytotechnology. 2009 Sep 27; Authors: Dai J, Zhang GL, Meng Q Gel entrapment culture of primary mammalian cells within collagen gel is one important configuration for construction of bioartificial organ as well as in vitro model for predicting drug situation in vivo. Gel contraction in entrapment culture, resulting from cell-mediated reorganization of the extracellular matrix, was commonly used to estimate cell viability. However, the exact influence of gel contraction on cell activities has rarely been addressed. This paper investigated the gel contraction under varying culture conditions and its effect on the activities of rat hepatocyte entrapped in collagen gel within hollow fibers. The hepatocyte activities were reflected by cell viability together with liver-specific functions on urea secretion and cytochrome P450 2E1. Unexpectedly, no gel contraction occurred during gel entrapment culture of hepatocyte under a high collagen concentration, but hepatocytes still maintained cell viability and liver-specific functions at a similar level to the other cultures with normal gel contraction. It seems that cell activities are unassociated with gel contraction. Alternatively, the mass transfer resistance induced by the combined effect of collagen concentration, gel contraction and cell density could be a side effect to reduce cell activities. The findings with gel entrapment culture of hepatocytes would be also informative for the other cell culture targeting pathological studies and tissue engineering. PMID: 19784829 [PubMed - as supplied by publisher] |
| Increased oral fibroblast lifespan is telomerase-independent.
September 29, 2009 at 8:38 am
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| | Increased oral fibroblast lifespan is telomerase-independent. J Dent Res. 2009 Oct;88(10):916-21 Authors: Enoch S, Wall I, Peake M, Davies L, Farrier J, Giles P, Baird D, Kipling D, Price P, Moseley R, Thomas D, Stephens P Oral mucosal wound-healing is characterized by rapid re-epithelialization and remodeling, with minimal scar formation. This may be attributed to the distinct phenotypic characteristics of the resident fibroblasts. To test this hypothesis, we investigated patient-matched oral mucosal and skin fibroblasts. Compared with skin fibroblasts, oral mucosal fibroblasts had longer proliferative lifespans, underwent more population doublings, and experienced senescence later, which was directly related to longer telomere lengths within oral mucosal fibroblasts. The presence of these longer telomeres was independent of telomerase expression, since both oral oral mucosal fibroblasts and skin fibroblasts were negative for active telomerase, as assessed according to the Telomeric Repeat Amplification Protocol. This study has demonstrated that, compared with skin fibroblasts, oral mucosal fibroblasts are 'younger', with a more embryonic/fetal-like phenotype that may provide a notable advantage for their ability to repair wounds in a scarless fashion. PMID: 19783799 [PubMed - in process] |
| Allogenic stem cell therapy improves right ventricular function by improving lung pathology in rats with pulmonary hypertension.
September 29, 2009 at 8:38 am
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| | Allogenic stem cell therapy improves right ventricular function by improving lung pathology in rats with pulmonary hypertension. Am J Physiol Heart Circ Physiol. 2009 Sep 25; Authors: Umar S, de Visser YP, Steendijk P, Schutte CI, Laghmani EH, Wagenaar GT, Bax WH, Mantikou E, Pijnappels DA, Atsma DE, Schalij MJ, van der Wall EE, van der Laarse A Pulmonary arterial hypertension (PAH) is a chronic lung disease that leads to right ventricular hypertrophy (RVH), remodeling and failure. We tested treatment with bone marrow-derived mesenchymal stem cells (MSCs) obtained from donor rats with monocrotaline (MCT)-induced PAH to recipient rats with MCT-induced PAH on pulmonary artery pressure, lung pathology and RV function. This model was chosen to mimic autologous MSC therapy. At day 1, PAH was induced by MCT (60 mg/kg) in 20 female Wistar rats. At day 14, rats were treated with 10(6) MSCs i.v. (MCT+MSC) or saline (MCT60). MSCs were obtained from donor rats with PAH at 28 days after MCT. A control group received saline at days 1 and 14. At day 28 RV function of recipient rats was assessed, followed by isolation of lungs and heart. RVH was quantified by weight ratio of RV/(LV+interventricular septum). MCT induced an increase of RV peak pressure from 27+/-5 to 42+/-17 mmHg, RVH (from 0.25+/-0.04 to 0.47+/-0.12), depressed RV ejection fraction (RVEF) (from 56+/-11 to 43+/-6%) and increased lung weight (from 0.96+/-0.15 to 1.66+/-0.32 g) including thickening of arteriolar walls and alveolar septa. MSC treatment attenuated PAH (31+/-4 mmHg), RVH (0.32+/-0.07), normalized RVEF (52+/-5%), reduced lung weight (1.16+/-0.24 g) and inhibited thickening of arterioles and alveolar septa. We conclude that application of MSCs from donor rats with PAH reduces RV pressure overload, RV dysfunction, and lung pathology in recipient rats with PAH. These results suggest that autologous MSC therapy may alleviate cardiac and pulmonary symptoms in PAH patients. Key words: stem cells, pulmonary arterial hypertension, heart failure, hypertrophy. PMID: 19783775 [PubMed - as supplied by publisher] |
| Early lineage specification of long-lived germline precursors in the colonial ascidian Botryllus schlosseri.
September 29, 2009 at 8:38 am
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| | Early lineage specification of long-lived germline precursors in the colonial ascidian Botryllus schlosseri. Development. 2009 Oct;136(20):3485-94 Authors: Brown FD, Tiozzo S, Roux MM, Ishizuka K, Swalla BJ, De Tomaso AW In many taxa, germline precursors segregate from somatic lineages during embryonic development and are irreversibly committed to gametogenesis. However, in animals that can propagate asexually, germline precursors can originate in adults. Botryllus schlosseri is a colonial ascidian that grows by asexual reproduction, and on a weekly basis regenerates all somatic and germline tissues. Embryonic development in solitary ascidians is the classic example of determinative specification, and we are interested in both the origins and the persistence of stem cells responsible for asexual development in colonial ascidians. In this study, we characterized vasa as a putative marker of germline precursors. We found that maternally deposited vasa mRNA segregates early in development to a posterior lineage of cells, suggesting that germline formation is determinative in colonial ascidians. In adults, vasa expression was observed in the gonads, as well as in a population of mobile cells scattered throughout the open circulatory system, consistent with previous transplantation/reconstitution results. vasa expression was dynamic during asexual development in both fertile and infertile adults, and was also enriched in a population of stem cells. Germline precursors in juveniles could contribute to gamete formation immediately upon transplantation into fertile adults, thus vasa expression is correlated with the potential for gamete formation, which suggests that it is a marker for embryonically specified, long-lived germline progenitors. Transient vasa knockdown did not have obvious effects on germline or somatic development in adult colonies, although it did result in a profound heterochrony, suggesting that vasa might play a homeostatic role in asexual development. PMID: 19783737 [PubMed - in process] |
| Films based on human hair keratin as substrates for cell culture and tissue engineering.
September 29, 2009 at 8:38 am
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| | Films based on human hair keratin as substrates for cell culture and tissue engineering. Biomaterials. 2009 Sep 22; Authors: Reichl S Keratin from hair or wool has been proposed as an appropriate material for producing films or cell cultivation scaffolds. The current study was performed to characterize two different approaches involving substrate coating based on keratin from human hair. Our goal was to evaluate cell growth behavior in these systems in comparison with a standard polystyrene substrate. The coating was made in two different ways: (i) by trichloroacetic acid precipitation or (ii) by casting a keratin nanosuspension. The resulting films were characterized using SDS-PAGE, SEM, and X-ray studies. The growth behaviors of twelve cell lines on the keratin films and on polystyrene were estimated using proliferation studies. Furthermore, we assessed the cell detachment behavior during trypsinization and the seeding efficiency. For epithelial cell lines with tight junction proteins, the transepithelial electrical resistance was measured and compared with values achieved using common coating materials. Both of the keratin coatings exhibited similar protein patterns and X-ray diffraction profiles, but we also detected differences in the transparency and ultrastructural surface morphologies. Culture dishes coated with keratin nanoparticles were used to create a transparent substrate that supports cell adherence and improves cell growth as compared with uncoated polystyrene or coatings that use trichloroacetic acid precipitation. We conclude that this coating method may be a new promising substrate for standard cell cultivation. PMID: 19783297 [PubMed - as supplied by publisher] |
| Interaction of human mesenchymal stem cells with osteopontin coated hydroxyapatite surfaces.
September 29, 2009 at 8:38 am
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| | Interaction of human mesenchymal stem cells with osteopontin coated hydroxyapatite surfaces. Colloids Surf B Biointerfaces. 2009 Aug 25; Authors: Jensen T, Dolatshahi-Pirouz A, Foss M, Baas J, Lovmand J, Duch M, Pedersen FS, Kassem M, Bünger C, Søballe K, Besenbacher F In vitro studies of the initial attachment, spreading and motility of human bone mesenchymal stem cells have been carried out on bovine osteopontin (OPN) coated hydroxyapatite (HA) and gold (Au) model surfaces. The adsorption of OPN extracted from bovine milk was monitored by the quartz crystal microbalance with dissipation (QCM-D) and the ellipsometry techniques, and the OPN coated surfaces were further investigated by antigen-antibody interaction. It is shown that the OPN surface mass density is significantly lower and that the number of antibodies binding to the resulting OPN layers is significantly higher on the HA as compared to the Au surfaces. The initial attachment, spreading and motility of human mesenchymal stem cells show a larger cell area, a faster arrangement of vinculin in the basal cell membrane and more motile cells on the OPN coated HA surfaces as compared to the OPN coated Au surfaces and to the uncoated Au and HA surfaces. These in vitro results indicate that there may be great potential for OPN coated biomaterials, for instance as functional protein coatings or drug delivery systems on orthopaedic implants or scaffolds for tissue-engineering. PMID: 19783129 [PubMed - as supplied by publisher] |
| Regenerative medicine: A primer for paediatricians.
September 29, 2009 at 8:38 am
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| | Regenerative medicine: A primer for paediatricians. Early Hum Dev. 2009 Sep 25; Authors: Polak DJ Regenerative medicine is a multidisciplinary field concerned with the replacement, repair or restoration of injured tissues. Cell therapy and tissue engineering are part of the broader remit of regenerative medicine. The ultimate aim is to provide safe and efficient therapies for a large number of clinical conditions. Novel regenerative therapies are already in use in initial clinical trials. The main components of regenerative medicine are cells and specially designed materials. A vast variety of cells types are currently used including: adult and stem cells. Equally a large number of natural and man-made materials have been investigated. Despite of considerable advances many challenges lie ahead. These are summarised in this review article. The field is slowly maturing and the initial unhelpful hype has been replaced by a more measured, mature and realistic outlook. PMID: 19783108 [PubMed - as supplied by publisher] |
| Thermosensitive injectable hyaluronic acid hydrogel for adipose tissue engineering.
September 29, 2009 at 8:38 am
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| | Thermosensitive injectable hyaluronic acid hydrogel for adipose tissue engineering. Biomaterials. 2009 Sep 25; Authors: Tan H, Ramirez CM, Miljkovic N, Li H, Rubin JP, Marra KG A series of thermosensitive copolymer hydrogels, aminated hyaluronic acid-g-poly(N-isopropylacrylamide) (AHA-g-PNIPAAm), were synthesized by coupling carboxylic end-capped PNIPAAm (PNIPAAm-COOH) to AHA through amide bond linkages. AHA was prepared by grafting adipic dihydrazide to the HA backbone and PNIPAAm-COOH copolymer was synthesized via a facile thermo-radical polymerization technique by polymerization of NIPAAm using 4,4'-azobis(4-cyanovaleric acid) as an initiator, respectively. The structure of AHA and AHA-g-PNIPAAm copolymer was determined by (1)H NMR. Two AHA-g-PNIPAAm copolymers with different weight ratios of PNIPAAm on the applicability of injectable hydrogels were characterized. The lower critical solution temperature (LCST) of AHA-g-PNIPAAm copolymers in PBS were measured as approximately 30 degrees C by rheological analysis, regardless of the grafting degrees. Enzymatic resistance of AHA-g-PNIPAAm hydrogels with 28% and 53% of PNIPAAm in 100U/mL hyaluronidase/PBS at 37 degrees C was 12.3% and 37.6% over 28 days, respectively. Equilibrium swelling ratios of AHA-g-PNIPAAm hydrogels with 28% of PNIPAAm were 21.5, and significantly decreased to 13.3 with 53% of PNIPAAm in PBS at 37 degrees C. Results from SEM observations confirm a porous 3D AHA-g-PNIPAAm hydrogel structure with interconnected pores after freeze-drying and the pore diameter depends on the weight ratios of PNIPAAm. Encapsulation of human adipose-derived stem cells (ASCs) within hydrogels showed the AHA-g-PNIPAAm copolymers were noncytotoxic and preserved the viability of the entrapped cells. A preliminary in vivo study demonstrated the usefulness of the AHA-g-PNIPAAm copolymer as an injectable hydrogel for adipose tissue engineering. This newly described thermoresponsive AHA-g-PNIPAAm copolymer demonstrated attractive properties to serve as cell or pharmaceutical delivery vehicles for a variety of tissue engineering applications. PMID: 19783043 [PubMed - as supplied by publisher] |
| The nanofibrous architecture of poly(l-lactic acid)-based functional copolymers.
September 29, 2009 at 8:38 am
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| | The nanofibrous architecture of poly(l-lactic acid)-based functional copolymers. Biomaterials. 2009 Sep 25; Authors: Liu X, Ma PX It remains a challenge to synthesize functional materials that can develop advanced scaffolding architectures for tissue engineering. In this study, a series of biodegradable amphiphilic poly(hydroxyalkyl (meth)acrylate)-graft-poly(l-lactic acid) (PHAA-g-PLLA) copolymers have been synthesized and fabricated into nano-fibrous scaffolds. These copolymers can be further functionalized, are more hydrophilic, and have faster degradation rates than the PLLA homopolymer, which are advantageous for certain tissue engineering applications. First, PLLA-based macromonomers were prepared by using functional hydroxyalkyl (meth)acrylates (HAA) as initiators. The PHAA-g-PLLA copolymers were then synthesized using free radical copolymerization of PLLA-based macromonomers and HAA. Nano-fibrous architecture was created using a thermally induced phase separation technique from these functional PHAA-g-PLLA copolymers. The nano-fibrous structure mimics the architecture of natural collagen matrix at the nanometer scale. The effects of the macromonomer composition, copolymer composition, blending ratio, and solvent selection on nano-scale structures were studied. In general, the nano-fibrous structure was created when the amount of HAA in the macromonomer was low. By increasing the amount of HAA in the macromonomer, microspheres with nano-fibrous surfaces were obtained. Further increasing the amount of HAA led to the creation of microspheres with leaf-like surfaces. These PLLA-based materials had much faster degradation rates than the PLLA, and could be completely degraded from several weeks to a few months depending on their composition and molecular weight. Furthermore, the PHAA-g-PLLA copolymers possess functional hydroxyl groups, which can be used to couple with bioactive molecules to control cell-material interactions. Therefore, these biodegradable functional copolymers have the design flexibility to fabricate various biomimetic materials for tissue engineering applications. PMID: 19783035 [PubMed - as supplied by publisher] |
| Modulating cellular adhesion through nanotopography.
September 29, 2009 at 8:38 am
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| | Modulating cellular adhesion through nanotopography. Biomaterials. 2009 Sep 25; Authors: Decuzzi P, Ferrari M Cellular adhesion is a fundamental process in the development of scaffolds for tissue engineering; in the design of biosensors and in preparing antibacterial substrates. A theoretical model is presented for predicting the strength of cellular adhesion to originally inert surfaces as a function of the substrate topography, accounting for both specific (ligand-receptor) and non-specific interfacial interactions. Three regimes have been identified depending on the surface energy (gamma) of the substrate: for small gamma, any increase in roughness is detrimental to adhesion; for large gamma, an optimal roughness exists that maximizes adhesion; and for intermediate gamma, surface roughness has a minor effect on adhesion. The results presented are in qualitative agreement with several experimental observations and can capture the long-term equilibrium configuration of the system. The model proposed supports the notion for rationally designing substrates where topography and physico-chemical properties are tailored to favour cellular proliferation whilst repelling bacterial adhesion. PMID: 19783034 [PubMed - as supplied by publisher] |
| Effects of Granulocyte Colony-Stimulating Factor on the Proliferation and Cell-Fate Specification of Neural Stem Cells.
September 29, 2009 at 8:38 am
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| | Effects of Granulocyte Colony-Stimulating Factor on the Proliferation and Cell-Fate Specification of Neural Stem Cells. Neuroscience. 2009 Sep 24; Authors: Liu H, Jia D, Fu J, Zhao S, He G, Ling EA, Gao J, Hao A Granulocyte-colony stimulating factor is a growth factor that regulates proliferation, differentiation and survival of hematopoietic progenitor cells. There is growing evidence to suggest that G-CSF exerts a powerful neuroprotective effect in different neurological disorders. However, it has remained to be elucidated if G-CSF has a direct effect on neural stem cells (NSCs). Here, we show that G-CSF could stimulate the proliferation of NSCs and promote their differentiation in vitro. Additionally, we have shown that G-CSF-induced proliferation of NSCs is associated with phosphorylation of STAT3, and the differentiation is linked to altered expression of differentiation-related genes. Remarkably, G-CSF could not initiate the differentiation of NSCs. The added roles of G-CSF in regulating proliferation and differentiation of NSCs as shown in this study would serve as a useful reference in designing new stem cell therapy strategies for promoting brain recovery and repair. PMID: 19782730 [PubMed - as supplied by publisher] |
| Tissue-engineered skin substitutes in regenerative medicine.
September 29, 2009 at 8:38 am
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| | Tissue-engineered skin substitutes in regenerative medicine. Curr Opin Biotechnol. 2009 Sep 24; Authors: Mansbridge J Recent advance in cellular tissue-engineered skin constructs have refined the applications already commercially available, in particular, by the use of genetically modified cells to enhance their properties on the treatment of wounds and to ease the application of epidermis using sprayed keratinocytes. This approach lends itself to use of chimeric epidermis, cultured allogeneic cells, to provide short-term coverage, together with minimally cultured autologous cells for long-term repair. Experimental models of skin include pathological conditions, phenomena such as aging and organogenesis, as in the hair follicle grown from isolated cells in vitro. The recent development of induced pluripotent stem cells raises the possibility of realizing the dream of skin and even limb regeneration shown by animals such as the salamander. PMID: 19782559 [PubMed - as supplied by publisher] |
| Controlled compaction with ruthenium-catalyzed photochemical cross-linking of fibrin-based engineered connective tissue.
September 29, 2009 at 8:38 am
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| | Controlled compaction with ruthenium-catalyzed photochemical cross-linking of fibrin-based engineered connective tissue. Biomaterials. 2009 Sep 24; Authors: Syedain ZH, Bjork J, Sando L, Tranquillo RT Tissue engineering utilizing fibrin gel as a scaffold has the advantage of creating a completely biological replacement. Cells seeded in a fibrin gel can induce fibril alignment by traction forces when subjected to appropriate mechanical constraints. While gel compaction is key to successful tissue fabrication, excessive compaction can result due to low gel stiffness. This study investigated using ruthenium-catalyzed photo-cross-linking as a method to increase gel stiffness in order to minimize over-compaction. Cross-links between the abundant tyrosine molecules that comprise fibrin were created upon exposure to blue light. Cross-linking was effective in increasing the stiffness of the fibrin gel by 93% with no adverse effects on cell viability. Long-term culture of cross-linked tubular constructs revealed no detrimental effects on cell proliferation or collagen deposition due to cross-linking. After 4 weeks of cyclic distension, the cross-linked samples were more than twice as long as non-cross-linked controls, with similar cell and collagen contents. However, the cross-linked samples required a longer incubation period to achieve a UTS and modulus comparable to controls. This study shows that photo-cross-linking is an attractive option to stiffen the initial fibrin gel and thereby reduce cell-induced compaction, which can allow for longer incubation periods and thus more tissue growth without compaction below a useful size. PMID: 19782397 [PubMed - as supplied by publisher] |
| Engineering human neo-tendon tissue in vitro with human dermal fibroblasts under static mechanical strain.
September 29, 2009 at 8:38 am
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| | Engineering human neo-tendon tissue in vitro with human dermal fibroblasts under static mechanical strain. Biomaterials. 2009 Sep 24; Authors: Deng D, Liu W, Xu F, Yang Y, Zhou G, Zhang WJ, Cui L, Cao Y Proper cell source is one of the key issues for tendon engineering. Our previous study showed that dermal fibroblasts could be used to successfully engineer tendon in vivo and tenocytes could engineer neo-tendon in vitro with static strain. This study further investigated the possibility of engineering human neo-tendon tissue in vitro using dermal fibroblasts. Human dermal fibroblasts were seeded on polyglycolic acid (PGA) fibers pre-fixed on a U-shape as a mechanical loading group, or simply cultured in a dish as a tension-free group. In addition, human tenocytes were also seeded on PGA fibers with tension as a comparison to human dermal fibroblasts. The results showed that human neo-tendon tissue could be generated using dermal fibroblasts during in vitro culture under static strain and the tissue structure became more mature with the increase of culture time. Longitudinally aligned collagen fibers and spindle shape cells were observed histologically and collagen fibril diameter and tensile strength increased with time and reached a peak at 14 weeks. In contrast, the dermal fibroblast-PGA constructs failed to form neo-tendon, but formed disorganized fibrous tissue in tension-free condition with significantly weaker strength and poor collagen fiber formation. Interestingly, neo-tendon tissues generated with human dermal fibroblasts were indistinguishable from the counterpart engineered with human tenocytes, which supports the viewpoint that human dermal fibroblasts is likely to replace tenocytes for future tendon graft development in vitro with dynamic mechanical loading in a bioreactor system. PMID: 19782396 [PubMed - as supplied by publisher] |
| Anti-inflammatory peptide-functionalized hydrogels for insulin-secreting cell encapsulation.
September 29, 2009 at 8:38 am
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| | Anti-inflammatory peptide-functionalized hydrogels for insulin-secreting cell encapsulation. Biomaterials. 2009 Sep 24; Authors: Su J, Hu BH, Lowe WL, Kaufman DB, Messersmith PB Pancreatic islet encapsulation within semi-permeable materials has been proposed for transplantation therapy of type I diabetes mellitus. Polymer hydrogel networks used for this purpose have been shown to provide protection from islet destruction by immunoreactive cells and antibodies. However, one of the fundamental deficiencies with current encapsulation methods is that the permselective barriers cannot protect islets from cytotoxic molecules of low molecular weight that are diffusible into the capsule material, which subsequently results in beta-cell destruction. Use of materials that can locally inhibit the interaction between the permeable small cytotoxic factors and islet cells may prolong the viability and function of encapsulated islet grafts. Here we report the design of anti-inflammatory hydrogels supporting islet cell survival in the presence of diffusible pro-inflammatory cytokines. We demonstrated that a poly(ethylene glycol)-containing hydrogel network, formed by native chemical ligation and presenting an inhibitory peptide for islet cell surface IL-1 receptor, was able to maintain the viability of encapsulated islet cells in the presence of a combination of cytokines including IL-1beta, TNF-alpha, and INF-gamma. In stark contrast, cells encapsulated in unmodified hydrogels were mostly destroyed by cytokines which diffused into the capsules. At the same time, these peptide-modified hydrogels were able to efficiently protect encapsulated cells against beta-cell specific T-lymphocytes and maintain glucose-stimulated insulin release by islet cells. With further development, the approach of encapsulating cells and tissues within hydrogels presenting anti-inflammatory agents may represent a new strategy to improve cell and tissue graft function in transplantation and tissue engineering applications. PMID: 19782393 [PubMed - as supplied by publisher] |
| On the effect of substrate curvature on cell mechanics.
September 29, 2009 at 8:38 am
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| | On the effect of substrate curvature on cell mechanics. Biomaterials. 2009 Sep 23; Authors: Sanz-Herrera JA, Moreo P, García-Aznar JM, Doblaré M Cell movement on a substrate or within the extracellular matrix is the phenomenological response to a biochemical signals' cascade transcripted into biophysical processes and viceversa. The process is complex in nature, including different length scales from the whole cell to organelle and protein levels, where substrate/ECM curvature has been shown to play an important role on cell's behavior. From a macroscopic perspective, the cytoskeleton may be modeled as a continuum body unbalanced by internal protein motors. In this work, we propose a cell constitutive model to simulate cell attachment on curved substrates, activated by contractile forces. We first analyze a single fiber bundle composed by microtubules, actin filaments and myosin machinery. Then, the model is macroscopically extended to the cytoskeletal level using homogenization. Substrate curvature has two implications in our model: (i) it forces fibers to work in a curved (bent) position and (ii) it eventually creates a pre-deformation state in the cytoskeleton. Interestingly, the model shows higher contractile force inhibition as curvature increases when implemented over different substrate morphologies, being this consistent with experimental results. The presented model may result useful in many new regenerative medicine techniques, miniaturized experimental tests, or to analyze cell behavior on manufactured nanoscaffolds for tissue engineering. PMID: 19781764 [PubMed - as supplied by publisher] |
| Controlled presentation of recombinant proteins via a zinc-binding peptide-linker in two and three dimensional formats.
September 29, 2009 at 8:38 am
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| | Controlled presentation of recombinant proteins via a zinc-binding peptide-linker in two and three dimensional formats. Biomaterials. 2009 Sep 23; Authors: Doran MR, Markway BD, Croll TI, Sara S, Munro TP, Cooper-White JJ The presentation of proteins on surfaces is fundamental to numerous cell culture and tissue engineering applications. While a number of physisorption and cross-linking methods exist to facilitate this process, few avoid denaturation of proteins or allow control over protein orientation, both of which are critical to the functionality of many signal proteins and ligands. Often recombinant protein sequences include a poly-histidine tag to facilitate purification. We utilize this sequence to anchor proteins to biosurfaces via a peptide bonded to the surface which conjugates with the poly-histidine tag in the presence of zinc rather than nickel, which is more traditionally used to conjugate poly-histidine tags to surfaces. We demonstrate that this strategy enables the display of proteins on 2D and 3D surfaces without compromising protein function through direct cross-linking or physisorption. PMID: 19781762 [PubMed - as supplied by publisher] |
| Repair of left ventricular aneurysm: ten-year experience in Chinese patients.
September 29, 2009 at 8:38 am
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| | Repair of left ventricular aneurysm: ten-year experience in Chinese patients. Chin Med J (Engl). 2009 Sep 5;122(17):1963-8 Authors: Fan HG, Zheng Z, Feng W, Yuan X, Wang W, Hu SS BACKGROUND: A large transmural myocardial infarction often results in a dyskinetic or akinetic left ventricular aneurysm (LVA). This study aimed to explore the early and long-term clinical outcomes and to identify predictors for survivals and hospital re-admission after the repair of left ventricular aneurysm. METHODS: We followed up 497 patients who had undergone LVA repair from a single center in China between 1995 and 2005. The perioperative parameters were recorded. Risk factors for early mortality and long-term results were analyzed by multivariate Logistic regression. Cox's proportional hazard model was used to calculate risk factors for major adverse cardiac and cerebrovascular events, cause of death and re-admission. Kaplan-Meier curve was employed to analyze long-term survival. RESULTS: The operative mortality was 2.0%. The long-term mortality was 11.1% and cardiac causes contributed to 61.8% of the overall long-term mortality. Four hundred and thirty-two patients survived during the follow-up period and 37.5% of them had been re-admitted at least one time. One hundred and five patients experienced major adverse cardiac and cerebrovascular events. Survival analysis exhibited that the probability of survival at 1 and 5 years after operation was 96% and 86% respectively. Previous atrial fibrillation was the independent risk factor for early mortality. Independent risk factors for long-term mortality were poor left ventricular ejection fraction and stroke,and risk factors for cardiac mortality were intraventricular block, stroke and poor left ventricular ejection fraction. Stroke, intraventricular block and advanced age were independent risk factors for major adverse cardiac and cerebrovascular events, and New York Heart Association (NYHA) class III-IV was the only risk factor for hospital re-admission. CONCLUSIONS: Postinfarction LVA can be repaired and satisfying early and long-term clinical outcome can be obtained. Endoventricular circular plasty technique is the better choice than linear repair in patients with large LVA. Survival is affected in patients with poor heart function, intraventricular block and stroke. PMID: 19781378 [PubMed - in process] |
| Current state of myocardial tissue engineering.
September 29, 2009 at 8:38 am
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| | Current state of myocardial tissue engineering. Chin Med J (Engl). 2009 Aug 5;122(15):1811-5 Authors: Xing YJ, Lü AL, Zhao XM, Li F, Wang L, DU JJ PMID: 19781331 [PubMed - in process] |
| [The current state of stem cells and myocardial tissue engineering research.]
September 29, 2009 at 8:38 am
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| | [The current state of stem cells and myocardial tissue engineering research.] Zhonghua Xin Xue Guan Bing Za Zhi. 2009 Mar;37(3):280-2 Authors: Wu KH, Mo XM, Liu YL PMID: 19781158 [PubMed - in process] |
| [The Chinese coronary artery bypass grafting registry report: 2004-2005.]
September 29, 2009 at 8:38 am
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| | [The Chinese coronary artery bypass grafting registry report: 2004-2005.] Zhonghua Xin Xue Guan Bing Za Zhi. 2009 Mar;37(3):240-243 Authors: , Hu SS OBJECTIVE: Number of coronary artery bypass grafting (CABG) increased steadily during the past decade as a result of a higher incidence of coronary artery disease in China. However, little is known about the current status of CABG surgery in contemporary China. This study was to get exact information on CABG in China. METHODS: A national multicentre database of patients undergoing CABG with the name of the Chinese CABG Registry Study was established at Fuwai hospital, Beijing, China which is the biggest cardiac centre of China in 2006 and 32 centers of cardiac surgery all over China (mainland) participated in the study. Registry forms were used to collect related information of patients undergoing CABG in these centers for statistical analysis. RESULTS: From January 2004 to December 2005, CABG was performed in 9247 consecutive patients with coronary artery disease. Mean age was (62.1 +/- 9.1) years and 21.5% patients were female, 76.7% patients had triple vessel disease, and 25.8% patients had left main disease. Overall in-hospital mortality was 3.3%. The in-hospital mortality of isolated CABG was 2.2%. CONCLUSION: The in-hospital mortality and the incidences of major accidents of surgery were low in these patients underwent CABG. The operative risk evaluating system for the Chinese CABG patients should be established to improve the survival of CABG operation in China. PMID: 19781149 [PubMed - as supplied by publisher] |
| Human adipose tissue precursor cells: a new factor linking regulation of fat mass to obesity and type 2 diabetes?
September 29, 2009 at 8:38 am
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| | Human adipose tissue precursor cells: a new factor linking regulation of fat mass to obesity and type 2 diabetes? Arch Physiol Biochem. 2009 Oct;115(4):218-26 Authors: Perrini S, Cignarelli A, Ficarella R, Laviola L, Giorgino F The current epidemic of obesity has caused a surge of interest in the study of the mechanisms regulating adipose tissue formation. It has been observed that adipose tissue contains a pool of adult stem cells with multipotent properties, which provide for the physiological cell turnover, and can be isolated and potentially utilized for tissue engineering and regenerative medical applications. These "stromal" cells exhibit pre-adipocyte characteristics, can be isolated from adipose tissue of adult subjects, propagated in vitro, and induced to differentiate into adipocytes. Different populations of multi-potent precursor cells can be isolated from human fat fragments. Thus, adipose precursors cells are a heterogeneous cells population, consisting of fibroblast-like multi-potential stem cells generally termed adipose-derived stem cells (ASCs). In this review, we discuss some aspects of ASCs basic biology, the methodology involved in ASCs isolation and culture, and some implications of ASCs availability for the understanding of metabolic diseases in humans. PMID: 19780715 [PubMed - in process] |
| Responses of adipose-derived stem cells during hypoxia: enhanced skin-regenerative potential.
September 29, 2009 at 8:38 am
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| | Responses of adipose-derived stem cells during hypoxia: enhanced skin-regenerative potential. Expert Opin Biol Ther. 2009 Sep 28; Authors: Chung HM, Won CH, Sung JH Mesenchymal stem cells within the stromal-vascular fraction of subcutaneous adipose tissue (i.e., adipose-derived stem cells (ASCs)), have been used for tissue engineering. In addition to serving a building-block function, ASCs are reported to secrete growth factors that are essential for their function. Increasing evidence indicates that ASCs play a significant role in skin regeneration, a function that is enhanced by hypoxia through upregulating secretion of growth factors. Although the anatomical sites of ASCs in the body are relatively oxygen-deficient, ASCs are usually cultured under normoxic conditions (i.e., atmospheric oxygen levels). Culturing ASCs under physiologically relevant low-oxygen-tension conditions may uniquely benefit the expansion, differentiation, adhesion, growth factor secretion and regenerative potential of ASCs. Therefore, understanding the response and adaptation of ASCs to hypoxia may be invaluable for developing novel cell- and cyto-therapy strategies. This review highlights our current understanding of cellular and molecular responses of ASCs to hypoxia, focusing on the enhancement of ASC function and secretory activity by hypoxic culture conditions. PMID: 19780713 [PubMed - as supplied by publisher] |
| Acellular cardiac extracellular matrix as a scaffold for tissue engineering: In-vitro cell support, remodeling and biocompatibility.
September 29, 2009 at 8:38 am
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| | Acellular cardiac extracellular matrix as a scaffold for tissue engineering: In-vitro cell support, remodeling and biocompatibility. Tissue Eng Part C Methods. 2009 Sep 25; Authors: Eitan Y, Sarig U, Dahan N, Machluf M We have developed an efficient decellularization process for the isolation of extracellular matrix (ECM) from native cardiac tissue. The isolated ECM exhibited desirable mechanical properties in terms of elasticity, strength and durability, properties required from scaffolds used for cardiac tissue repair. The present study further investigates the potential use of this scaffold for cardiac tissue engineering or repair in terms of interactions with seeded cells and biocompatibility. We used the commonly studied fibroblasts, cardiomyocytes and mesenchymal stem cells, which were isolated and seeded on the scaffold. Cell density and distribution were followed by DiO staining, and their proliferation and viability was assessed by AlamarBlue(R) assay and FDA/PI staining. Fibroblast seeded scaffolds shrank to 1-2mm3 spheroids, and their glycosaminoglycans significantly increased by 23%. The expression of ECM remodeling-related mRNAs of collagens I and III, MMP2 and TIMP1 was quantified by real-time PCR, and were significantly elevated in fibroblasts seeded scaffold, compared to control cells on plates. Fibroblast seeded scaffolds lost some flexibility, yet gained strength compared to acellular scaffolds, as shown by mechanical testing. Scaffold seeded with cardiomyocyte began to beat in concert few days post seeding and the myocytes expressed typical functional cardiac markers such as alpha-actinin, Troponin I and connexin43. The cells revealed aligned elongated morphology, as presented by immunofluorescent staining and SEM. Mesenchymal stem cells seeded scaffolds maintained viability over 24 days in culture. These findings further strengthen the potential use of acellular cardiac ECM as a biomaterial for heart regeneration. PMID: 19780649 [PubMed - as supplied by publisher] |
| Hemangioblastic characteristics of human adipose tissue-derived adult stem cells in vivo.
September 29, 2009 at 8:38 am
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| | Hemangioblastic characteristics of human adipose tissue-derived adult stem cells in vivo. Arch Med Res. 2009 May;40(4):311-7 Authors: Fang B, Luo S, Song Y, Li N, Cao Y Recent studies have demonstrated the existence of a population of adipose tissue-derived adult stem (ADAS) cells that can undergo multilineage differentiation in vitro. However, it remains unclear whether these cells maintain their multilineage potential in vivo. The aim of this study was to investigate whether Flk1(+)CD31(-)CD34(-) ADAS cells have characteristics of hemangioblasts. These human ADAS (hADAS) cells were able to differentiate into endothelial and hematopoietic cells at the single-cell level in vivo. These postnatal Flk1(+)CD31(-)CD34(-) hADAS cells bear characteristics of hemangioblast and may have potential application for the hematopoietic and vascular diseases. PMID: 19608022 [PubMed - indexed for MEDLINE] |
| Temporomandibular joint reconstruction.
September 29, 2009 at 8:38 am
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| | Temporomandibular joint reconstruction. Alpha Omegan. 2009 Jun;102(2):51-4 Authors: Mercuri LG Temporomandibular joint (TMJ) reconstruction presents unique problems because of the integral and complex roles this joint plays in establishing and maintaining proper form and function of the stomatognathic system. The TMJ not only acts as a secondary growth center for the mandible in prepubescence, but it is also essential for the functions of mastication, speech, airway support, and deglutition in both the child and the adult. PMID: 19591328 [PubMed - indexed for MEDLINE] |
| Contemporary oral and maxillofacial surgery.
September 29, 2009 at 8:38 am
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| | Contemporary oral and maxillofacial surgery. Alpha Omegan. 2009 Jun;102(2):45 Authors: Laskin DM PMID: 19591326 [PubMed - indexed for MEDLINE] |
| Primary cultures from rat vibrissae as a potential cell source for in vitro construction of urinary bladder wall grafts.
September 29, 2009 at 8:38 am
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| | Primary cultures from rat vibrissae as a potential cell source for in vitro construction of urinary bladder wall grafts. Transplant Proc. 2009 Jun;41(5):1932-5 Authors: Drewa T, Joachimiak R, Kaznica A, Sarafian V, Sir J BACKGROUND: In vitro-constructed grafts can be used for human bladder augmentation. There are many diseases in which autologous cells cannot be used for this purpose. The aim of the present study was to examine the potential of rat vibrissae hair follicle cells to form cultures, which could serve as a source for in vitro creation of urinary bladder wall grafts. METHODS: Two hundred vibrissae were excised from young Wistar male rats. Two different digestions were performed, in dispase and in collagenase. All follicles were additionally incubated in trypsin and ethylenediamine tetraacetic acid. Two different culture media based on DMEM (Dulbecco's Modified Eagle's Medium) were used: the first was supplemented with keratinocyte growth factor (KGF) and the second with epidermal growth factor. Immunocytochemical detection of cytokeratin, CD34, p63, Ki-67 (proliferation index), and HMB45 (Human Melanoma Black 45) was performed. RESULTS: Forty-eight primary cultures of rat follicle vibrissae cells were established from 200 hair follicles (24% successful rate). Twenty-four primary cultures were obtained after dispase digestion and 24 after collagenase treatment. Each group was cultured in 2 different media. A heterogeneity of primary cultures was observed. Cells formed a monolayer within a period of 2 to 4 weeks. The 24 primary cultures established after dispase treatment exhibited monolayers of small cuboid cells expressing cytokeratin and CD34. In the 40th passage 20%-40% of cells expressed p63; 85% of these cells from late passages were positive for Ki-67, indicating preserved mitotic potential. Epithelial-like phenotype was observed after dispase digestion and cultivation in KGF-supplemented medium. After 3 weeks, the morphology of these cells changed into fibroblast-like. These cultures were negative for CD34. Fibroblast-like cell growth was observed after collagenase treatment in both KGF- and EGF-supplemented media. These cells were positive for the melanocyte cell marker (HMB45). CONCLUSIONS: Culture media and isolation conditions influence hair follicle stem cell differentiation. The stem cell niche within the hair follicles is a reservoir of cells, which can be potentially used for in vitro creation of urinary bladder wall grafts. PMID: 19545759 [PubMed - indexed for MEDLINE] |
| T17b murine embryonal endothelial progenitor cells can be induced towards both proliferation and differentiation in a fibrin matrix.
September 29, 2009 at 8:38 am
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| | T17b murine embryonal endothelial progenitor cells can be induced towards both proliferation and differentiation in a fibrin matrix. J Cell Mol Med. 2009 May;13(5):926-35 Authors: Bleiziffer O, Horch RE, Hammon M, Arkudas A, Naschberger E, Rath S, Pryymachuk G, Beier JP, Hatzopoulos AK, Stürzl M, Kneser U Endothelial progenitor cells (EPC) may enhance blood vessel formation in a variety of clinical settings such as ischaemia and tumour angiogenesis as well as in tissue-engineered matrices. In the present study, we cultured a murine endothelial progenitor cell line, T17b, in vitro in cell culture as well as in an FDA-approved fibrin matrix and investigated cell proliferation, differentiation and secretion patterns of the angiogenic growth factor VEGF under hypoxia and differentiation. We show that T17b EPC remain viable for at least 8 days in the fibrin matrix where they proliferate and form clusters including lumen-like structures. Proliferation in fibrin clots overlayed with basal medium (BM) was confirmed morphologically and immunohistochemically by positive Ki67 staining, indicating mitotic activity. Significant cell proliferation and Ki-67 expression were absent when cells were incubated with dibutyryl-cAMP and retinoic acid (RA). Incubation with dibutyryl-cAMP and RA stimulated the expression of the EPC differentiation markers von Willebrand Factor (vWF) and VEGF receptor 2 (VEGFR-2), indicating successful differentiation in the fibrin clot. EPC differentiation induced by dibutyryl-cAMP and RA was confirmed in 2-D chamber slide cultures by positive vWF immunostaining, which was absent in BM controls. EPC chamber slides also displayed positive vWF staining when exposed to hypoxia under BM conditions, indicating EPC activation and differentiation could also be induced by hypoxia. Taken together, T17b EPC secrete increased levels of VEGF when submitted to either hypoxia or differentiation and can be differentiated into mature endothelial cells not only in cell and matrigel cultures but also in a fibrin matrix that is FDA approved for clinical application. PMID: 19538255 [PubMed - indexed for MEDLINE] | | | 
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