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| Biomaterial mediated epithelial-mesenchymal interaction of salivary tissue under serum free condition.
February 18, 2010 at 6:11 AM
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| | Biomaterial mediated epithelial-mesenchymal interaction of salivary tissue under serum free condition. Biomaterials. 2010 Jan;31(2):288-95 Authors: Yang TL, Hsiao YC, Lin SJ, Lee HW, Lou PJ, Ko JY, Young TH Many organs develop from epithelial-mesenchymal interactions such that in order to regenerate these organs, it might be a preferable strategy to recapitulate this process. However, in the current culture system designed for tissue interaction, the supplement of serum is required. The aim of this study is to explore the possibility of reproducing epithelial-mesenchymal interaction and ensuing morphogenesis in a serum-free condition. In accordance with the previous studies, by using a standard model of murine fetal submandibular gland (SMG), the tissue interaction and the morphogenesis were largely dependent on serum. Nonetheless, when tissue recombinants were cultivated on polyvinylidene fluoride (PVDF), but not on other biomaterials, the serum-deprived effect could be rescued. On PVDF, SMG tissue recombinant was able to increase epithelial size, de novo synthesize basement membrane, and develop new branches without serum. Although the gene expression levels of sel! ected morphogens were not significantly altered, the precise localization of morphogenetic-decisive extracellular matrix such as type III collagen and the superior adsorbing capacity of essential diffusible factors like fibroblast growth factor 7 (FGF7) might account for PVDF effect. Accordingly, the result demonstrates that it is possible to establish a serum-free system that is competent in facilitating epithelial-mesenchymal interaction of salivary tissue. With PVDF, the crosstalk between SMG epithelia and mesenchyme could be sustained without serum. PMID: 19853295 [PubMed - indexed for MEDLINE] | | |
| The development of a tissue-engineered artery using decellularized scaffold and autologous ovine mesenchymal stem cells.
February 18, 2010 at 6:11 AM
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| | The development of a tissue-engineered artery using decellularized scaffold and autologous ovine mesenchymal stem cells. Biomaterials. 2010 Jan;31(2):296-307 Authors: Zhao Y, Zhang S, Zhou J, Wang J, Zhen M, Liu Y, Chen J, Qi Z Alternatives to using native arteries in vascular surgery are urgently needed. Vessels made from synthetic polymers have shortcomings such as thrombosis, rejection, intimal hyperplasia, calcification, infection, chronic inflammation and no growth potential. Tissue-engineered blood vessels (TEBV) may overcome these problems. We developed a tissue-engineered artery using autologous bone marrow derived mesenchymal stem cells (MSCs) and a decellularized arterial scaffold. Vascular smooth muscle cell (SMCs)-like cells and endothelial cell (ECs)-like cells were differentiated from MSCs in vitro. We constructed TEBV by seeding these autologous cells onto decellularized ovine carotid arteries and interposed into the carotid arteries in an ovine host models. The scaffold retained the main structural components of a blood vessel, such as collagen and elastin. The TEBVs were patent, anti-thrombogenic, and mechanically stable for 5 months in vivo, whereas non-seeded grafts oc! cluded within 2 weeks. Histological, immunohistochemical, and electron microscopic analyses of the TEBVs demonstrated the existence of endothelium, smooth muscle and the presence of collagen and elastin both at 2 and 5 months, respectively. MSCs labeled with a fluorescent dye prior to implantation were detected in the harvested TE artery 2 months after implantation, indicating that the MSCs survived and contributed to the vascular tissue regeneration. Therefore, TEBVs can be assembled from autologous MSCs and decellularized bioscaffold. PMID: 19819544 [PubMed - indexed for MEDLINE] | | |
| Scaffolds with covalently immobilized VEGF and Angiopoietin-1 for vascularization of engineered tissues.
February 18, 2010 at 6:11 AM
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| | Scaffolds with covalently immobilized VEGF and Angiopoietin-1 for vascularization of engineered tissues. Biomaterials. 2010 Jan;31(2):226-41 Authors: Chiu LL, Radisic M The aim of this study was to engineer a biomaterial capable of supporting vascularization in vitro and in vivo. We covalently immobilized vascular endothelial growth factor (VEGF) and Angiopoietin-1 (Ang1) onto three-dimensional porous collagen scaffolds using 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride (EDC) chemistry. Over both 3 and 7 days in vitro, seeded endothelial cells (ECs) had increased proliferation on scaffolds with immobilized VEGF and/or Ang1 compared to unmodified scaffolds and soluble growth factor controls. Notably, the group with co-immobilized VEGF and Ang1 showed significantly higher cell number (P=0.0079), higher overall lactate production rate (P=0.0044) and higher overall glucose consumption rate (P=0.0034) at Day 3, compared to its corresponding soluble control for which growth factors were added to culture medium. By Day 7, hematoxylin and eosin, live/dead, CD31, and von Willebrand factor staining all showed improved tube f! ormation by ECs when cultivated on scaffolds with co-immobilized growth factors. Interestingly, scaffolds with co-immobilized VEGF and Ang1 showed increased EC infiltration in the chorioallantoic membrane (CAM) assay, compared to scaffolds with independently immobilized VEGF/Ang1. This study presents an alternative method for promoting the formation of vascular structures, via covalent immobilization of angiogenic growth factors that are more stable than soluble ones and have a localized effect. PMID: 19800684 [PubMed - indexed for MEDLINE] | | |
| Fabrication and characterization of porous tubular silk fibroin scaffolds.
February 18, 2010 at 6:11 AM
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| | Fabrication and characterization of porous tubular silk fibroin scaffolds. J Biomater Sci Polym Ed. 2009;20(13):1961-74 Authors: Min S, Gao X, Liu L, Tian L, Zhu L, Zhang H, Yao J Silk fibroin (SF) has been one of promising resources of biotechnology and biomedical materials due to its unique properties. Here, different sizes of porous tubular scaffolds were fabricated from a SF aqueous solution with the addition of poly(ethylene glycol diglycidyl ether) (PGDE). The scaffolds were generally flexible and transparent at the wet state with a pore size of 81-128 mum and porosity of 90-96%, depending on the concentrations of SF and PGDE. The mechanical properties measurement showed that the tubular SF scaffolds had satisfying tensile and compression properties, especially the excellent deformation-recovery ability. FT-IR spectra indicated that the SF in the tubular scaffolds was in a beta-sheet structure, and no PGDE characteristic band was observed, suggesting that the PGDE could be removed from the scaffolds by soaking in deionized water. The cell compatibility of scaffolds was evaluated, and no obvious cytotoxicity to mouse L-929 fibroblasts ! was detected. PMID: 19793450 [PubMed - indexed for MEDLINE] | | |
| Impact of RGD micro-patterns on cell adhesion.
February 18, 2010 at 6:11 AM
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| | Impact of RGD micro-patterns on cell adhesion. Colloids Surf B Biointerfaces. 2010 Jan 1;75(1):107-14 Authors: Chollet C, Lazare S, Guillemot F, Durrieu MC In order to avoid the problems related to biomaterial use (inflammation, infections, aseptic loosening, etc.), a new approach consisting of associating the material and autologous cells before implantation is being developed, thus requiring a perfect cooperation between the material's surface and the cell. To improve cell adhesion to biomaterials, a suitable method is to functionalize their surface by pro-adhesive ligand grafting. The aim of this study was to covalently graft RGD containing peptides onto a poly-(ethylene terephthalate) surface in well-defined microstructures in order to control MC3T3 cell adhesion. We followed two different routes for obtaining micro-patterned materials: (1) a photoablation technique using an excimer laser and (2) a photolithography process. The resulting patterns were characterized by optical microscopy, scanning electron microscopy, optical profilometry and high resolution mu-imager. The biological evaluation of cell adhesion on! to the micro-patterned surfaces was carried out using optical microscopy, scanning electron microscopy and fluorescence microscopy. Cells seeded onto photolithographical or photoablated micro-patterned PET exhibited an alignment with the RGD domains and appear to be connecting through pseudopods extending towards each other. Whatever the technique used to create micro-patterns, a cell alignment occurs once the thickness of the RGD line reaches approximately 100 microm. These results prove the importance of microstructured surfaces for the elaboration of tissue engineered biomaterials. PMID: 19775874 [PubMed - indexed for MEDLINE] | | |
| A novel three-dimensional tubular scaffold prepared from silk fibroin by electrospinning.
February 18, 2010 at 6:11 AM
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| | A novel three-dimensional tubular scaffold prepared from silk fibroin by electrospinning. Int J Biol Macromol. 2009 Dec 1;45(5):504-10 Authors: Zhou J, Cao C, Ma X Effects of electrospinning parameters (including voltage, collection distance, solution concentration and flow rate) on the morphology and diameter distribution of regenerated SF (silk fibroin) fiber were investigated. Afterward, SF tubular scaffold composed of homogenous fibers was fabricated at voltage of 18kV, collection distance of 18cm, concentration of 37%, and flow rate of 0.15mL/min. After methanol treatment, SF tubular scaffold showed tensile strength of 3.57MPa and porosity of 80.85%. It is satisfied that our work offers a simple method to fabricate seamless and porous tubular scaffold from SF without any additives and organic solvents. Furthermore, the results suggest that this tubular scaffold shows promising applications in small-diameter vascular graft. PMID: 19772871 [PubMed - indexed for MEDLINE] | | |
| Isolation of cancer-specific chimeric transcripts induced by hypomethylation of the LINE-1 antisense promoter.
February 18, 2010 at 6:11 AM
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| | Isolation of cancer-specific chimeric transcripts induced by hypomethylation of the LINE-1 antisense promoter. Genomics. 2009 Dec;94(6):397-406 Authors: Cruickshanks HA, Tufarelli C The antisense promoter of human LINE-1 (L1) retroelements can direct transcription of adjacent unique genomic sequences generating chimeric RNAs, which can perturb transcription of neighbouring genes. As L1 elements constitute 17% of the human genome, chimeric transcription is potentially widespread, but the extent to which this occurs is largely unknown. Using a genome-wide screen we have isolated novel chimeric transcripts that are unique to breast cancer cell lines, primary tumours and colon cancer cells. Expression of the cancer-specific chimeric transcripts can be induced in non-malignant breast epithelial cells by the demethylating drug 5-azacytidine. These findings indicate that loss of L1 methylation in cancer cells is linked to the expression of L1-chimeric transcripts which may therefore constitute a useful set of markers of malignancy. PMID: 19720139 [PubMed - indexed for MEDLINE] | | |
| Histone deacetylase 4 promotes TGF-beta1-induced synovium-derived stem cell chondrogenesis but inhibits chondrogenically differentiated stem cell hypertrophy.
February 18, 2010 at 6:11 AM
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| | Histone deacetylase 4 promotes TGF-beta1-induced synovium-derived stem cell chondrogenesis but inhibits chondrogenically differentiated stem cell hypertrophy. Differentiation. 2009 Dec;78(5):260-8 Authors: Pei M, Chen D, Li J, Wei L The transforming growth factor-beta (TGF-beta) superfamily members play diverse roles in cartilage development and maintenance. TGF-beta up-regulates chondrogenic gene expression by enhancing transcription factor SRY (sex determining region Y)-box 9 (Sox9) and inhibits osteoblast differentiation by repressing runt-related transcription factor 2 (Runx2). Recently, histone deacetylases (HDACs) were reported to act as negative regulators of chondrocyte hypertrophy. It was speculated that HDAC4 may promote TGF-beta1-induced MSC chondrogenesis. In this study, the adenovirus-mediated HDAC4 gene (Ad.HDAC4) was utilized to infect synovium-derived stem cells (SDSCs). Adenovirus-mediated LacZ (Ad.LacZ) served as a control. The infected cells were centrifuged to form SDSC pellets followed by incubation in a serum-free chondrogenic medium for 15 days with or without 10ng/mL TGF-beta1. Transfection efficiency was determined in SDSCs using Ad.LacZ. Cytotoxicity was measured usi! ng lactate dehydrogenase assay. Histology, immunostaining, biochemical analysis, and real-time polymerase chain reaction were performed to assess chondrogenesis at protein and mRNA levels in infected SDSCs. Our data demonstrated that supplementation with TGF-beta1 could initiate and promote SDSC chondrogenesis; however, TGF-beta1 alone was insufficient to fully differentiate SDSCs into chondrocytes. Ad.HDAC4 could be efficiently transfected into SDSCs. Without TGF-beta1 treatment, HDAC4 had no effect on SDSC chondrogenesis; however, in the presence of TGF-beta1, HDAC4 could speed up and maintain a high level of chondrogenesis while down-regulating the hypertrophic marker - type X collagen expression. This study is the first report showing that HDAC4 overexpression promotes TGF-beta1-induced SDSC chondrogenesis but inhibits chondrogenically differentiated stem cell hypertrophy. The mechanism underlying this process needs further investigation. PMID: 19716643 [PubMed - indexed for MEDLINE] | | |
| Release characteristics and osteogenic activity of recombinant human bone morphogenetic protein-2 grafted to novel self-assembled poly(lactide-co-glycolide fumarate) nanoparticles.
February 18, 2010 at 6:11 AM
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| | Release characteristics and osteogenic activity of recombinant human bone morphogenetic protein-2 grafted to novel self-assembled poly(lactide-co-glycolide fumarate) nanoparticles. J Control Release. 2009 Dec 3;140(2):148-56 Authors: Mercado AE, Ma J, He X, Jabbari E Functionalized biodegradable nanoparticles (NPs) provide reactive groups and large surface area for grafting recombinant human bone morphogenetic protein-2 (rhBMP-2) to reduce protein diffusion and maintain sufficient concentration for recruitment and differentiation of osteoprogenitor cells. The objective of this work was to investigate release characteristics and osteogenic activity of rhBMP-2, grafted to biodegradable NPs based on succinimide-terminated poly(lactide fumarate) (PLAF-NHS) and poly(lactide-co-glycolide fumarate) (PLGF-NHS) macromers. The release of rhBMP-2 from the NPs, measured by enzyme-linked immunosorbent assay, was linear with time in the first two weeks, and 24.70+/-1.30% and 48.7+/-0.7% of the protein grafted to PLGF-NHS and PLAF-NHS NPs, respectively, was released in the enzymatically active conformation after complete degradation/erosion of the NPs. After 14 days of incubation with bone marrow stromal (BMS) cells, rhBMP-2 grafted to PLAF-! NHS and PLGF-NHS NPs was as effective in inducing mineralization as the native rhBMP-2 that was directly added to the cell culture media. At any incubation time, rhBMP-2 grafted to PLAF had the highest expression of osteopontin (OP) and osteocalcin (OC), followed by rhBMP-2 grafted to PLGF and rhBMP-2 directly added to media. Higher OP and OC expression for BMP-gPLAF and BMP-gPLGF groups may be related to other factors in the cascade of osteogenesis, such as differentiation of BMS cells to the vasculogenic lineage and formation of a vascularized/mineralized matrix. PMID: 19699244 [PubMed - indexed for MEDLINE] | | |
| Combining scaffolds and osteogenic cells in regenerative bone surgery: a preliminary histological report in human maxillary sinus augmentation.
February 18, 2010 at 6:11 AM
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| | Combining scaffolds and osteogenic cells in regenerative bone surgery: a preliminary histological report in human maxillary sinus augmentation. Clin Implant Dent Relat Res. 2009 Oct;11 Suppl 1:e92-102 Authors: Mangano C, Piattelli A, Mangano A, Mangano F, Mangano A, Iezzi G, Borges FL, d'Avila S, Shibli JA PURPOSE: The following case series evaluated the maxillary sinus augmentation responses to tissue-engineered bone graft obtained by a culture of autogenous osteoblasts seeded on polyglycolic-polylactic scaffolds and calcium phosphate. MATERIALS AND METHODS: Sinus floor augmentation was performed bilaterally in five patients (mean age 58.4 years) with tissue-engineered bone (test site - Oral Bone, BioTissue, Freiburg, Germany) or calcium phosphate (control site - Biocoral, Novaxa Spa, Milan, Italy). Biopsies were harvested 6 months after sinus augmentation for histometric evaluation. Volumetric measurements were taken at baseline and 6 months after the surgical procedure. RESULTS: The mean of vertical bone gain was 6.47 +/- 1.39 mm and 9.14 +/- 1.19 mm to test and control sites, respectively. The histological sections depicted mature bone with compact and cancellous areas. All biopsies contained varying percentages of newly formed bone and marrow spaces. The mean o! f bone tissue in the grafted area was 37.32 +/- 19.59% and 54.65 +/- 21.17% for tissue-engineered bone and calcium phosphate, respectively. CONCLUSION: Within the limits of the present report, the histological data in humans confirmed that tissue-engineered bone and calcium phosphate allowed newly formed bone after maxillary sinus augmentation. PMID: 19673958 [PubMed - indexed for MEDLINE] | | |
| Evaluation of the long-term reconstituting subset of hematopoietic stem cells with CD150.
February 18, 2010 at 6:11 AM
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| | Evaluation of the long-term reconstituting subset of hematopoietic stem cells with CD150. Stem Cells. 2009 Oct;27(10):2498-508 Authors: Papathanasiou P, Attema JL, Karsunky H, Xu J, Smale ST, Weissman IL Blood is a tissue with a high cell turnover rate that is constantly being replenished by bone marrow hematopoietic stem cells (HSCs) seeded during fetal ontogeny from the liver. Here we show that the long-term (LT) reconstituting subset of cKit(+)Thy1.1(lo)Lin(-/lo)Sca1(+)Flk2(-) HSCs is CD150(+). HSCs sourced from the fetal liver show LT, multilineage engraftment from E14.5 onward, and the CD150 cell surface molecule can readily substitute Thy1.1 as a positive marker of LT-HSCs in this tissue. From both fetal liver and adult bone marrow, cKit(+)Thy1.1(lo)Lin(-/lo)Sca1(+)Flk2(-) CD150(+) cells exhibit robust LT competitive engraftment, self-renewal, multilineage differentiation capacity, and an accessible chromatin configuration consistent with high expression of erythroid/megakaryoid genes in purified cell subsets. Our data show that, with appropriate combinations of cell surface markers, stem cells can be accurately isolated to high purity and characterized. Thi! s is important for the clarification of lineage relationships and the identification of bona fide regulators of stem cell self-renewal and differentiation both in normal and neoplastic tissues. PMID: 19593793 [PubMed - indexed for MEDLINE] | | |
| Three-dimensional loading model for periodontal ligament regeneration in vitro.
February 18, 2010 at 6:11 AM
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| | Three-dimensional loading model for periodontal ligament regeneration in vitro. Tissue Eng Part C Methods. 2009 Dec;15(4):561-70 Authors: Berendsen AD, Smit TH, Walboomers XF, Everts V, Jansen JA, Bronckers AL In this study we present a new three-dimensional (3D) model to study effects of mechanical loading on tendon/ligament formation in vitro. The model mimics a functional periodontal ligament (PDL), which anchors dental roots to the jaw bone and transfers the axial load of mastication to the jaw bone. A collagen gel containing human PDL fibroblasts was seeded in a PDL space between an artificial root and bone surface. The effects of 3-day loading on the fibroblasts were studied in vitro by axial and intermittent displacement of the root to which the gel was attached. Cell responses were recorded by measuring expression of three sets of genes: (i) cyclooxygenase 1 and 2 (COX-1, COX-2) producing prostaglandins (signaling molecules); (ii) Runx2, a transcription factor for the osteogenic lineage; and (iii) the extracellular matrix proteins osteopontin, dentin matrix protein 1, and collagen type I (COL1). Loading for 3 days resulted in magnitude-dependent changes in the e! xpression of COX-2 and COL1. A low loading magnitude significantly decreased COX-2 expression, an intermediate magnitude increased its expression, while a high magnitude increased COL1 expression. We concluded that the 3D loading model provides a useful, well-controlled method to examine ligament fibroblast responses to mechanical loading. The model may serve to explore the application of mechanical loading as an anabolic factor for ligament reconstruction. PMID: 19216643 [PubMed - indexed for MEDLINE] | | |
| A new route to produce starch-based fiber mesh scaffolds by wet spinning and subsequent surface modification as a way to improve cell attachment and proliferation.
February 18, 2010 at 6:11 AM
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| | A new route to produce starch-based fiber mesh scaffolds by wet spinning and subsequent surface modification as a way to improve cell attachment and proliferation. J Biomed Mater Res A. 2010 Jan;92(1):369-77 Authors: Tuzlakoglu K, Pashkuleva I, Rodrigues MT, Gomes ME, van Lenthe GH, Müller R, Reis RL This study proposes a new route for producing fiber mesh scaffolds from a starch-polycaprolactone (SPCL) blend. It was demonstrated that the scaffolds with 77% porosity could be obtained by a simple wet-spinning technique based on solution/precipitation of a polymeric blend. To enhance the cell attachment and proliferation, Ar plasma treatment was applied to the scaffolds. It was observed that the surface morphology and chemical composition were significantly changed because of the etching and functionalization of the fiber surfaces. XPS analyses showed an increase of the oxygen content of the fiber surfaces after plasma treatment (untreated scaffolds O/C:0.32 and plasma-treated scaffolds O/C:0.41). Both untreated and treated scaffolds were examined using a SaOs-2 human osteoblast-like cell line during 2 weeks of culture. The cell seeded on wet-spun SPCL fiber mesh scaffolds showed high viability and alkaline phosphatase enzyme activity, with those values being ev! en higher for the cells seeded on the plasma-treated scaffolds. PMID: 19191314 [PubMed - indexed for MEDLINE] | | |
| An engineering, multiscale constitutive model for fiber-forming collagen in tension.
February 18, 2010 at 6:11 AM
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| | An engineering, multiscale constitutive model for fiber-forming collagen in tension. J Biomed Mater Res A. 2010 Jan;92(1):254-66 Authors: Annovazzi L, Genna F This work proposes a nonlinear constitutive model for a single collagen fiber. Fiber-forming collagen can exhibit different hierarchies of basic units, called fascicles, bundles, fibrils, microfibrils, and so forth, down to the molecular (tropocollagen) level. Exploiting the fact that at each hierarchy level the microstructure can be seen, at least approximately, as that of a wavy, or crimped, extensible cable, the proposed stress-strain model considers a given number of levels, each of which contributes to the overall mechanical behavior according to its own geometrical features (crimp, or waviness), as well as to the basic mechanical properties of the tropocollagen. The crimp features at all levels are assumed to be random variables, whose statistical integration furnishes a stress-strain curve for a collagen fiber. The soundness of this model-the first, to the Authors' knowledge, to treat a single collagen fiber as a microstructured nonlinear structural element! -is checked by its application to collagen fibers for which experimental results are available: rat tail tendon, periodontal ligament, and engineered ones. Here, no attempt is made to obtain a stress-strain law for generic collagenous tissues, which exhibit specific features, often much more complex than those of a single fiber. However, it is trivial to observe that the availability of a sound, microstructurally based constitutive law for a single collagen fiber (but applicable at any sub-level, or to any other material with a similar microstructure) is essential for assembling complex constitutive models for any collagenous fibrous tissue. PMID: 19180522 [PubMed - indexed for MEDLINE] | | |
| The effect of scaffold architecture on properties of direct 3D fiber deposition of porous Ti6Al4V for orthopedic implants.
February 18, 2010 at 6:11 AM
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| | The effect of scaffold architecture on properties of direct 3D fiber deposition of porous Ti6Al4V for orthopedic implants. J Biomed Mater Res A. 2010 Jan;92(1):33-42 Authors: Li JP, de Wijn JR, van Blitterswijk CA, de Groot K 3D porous Ti6Al4V scaffolds were directly fabricated by a rapid prototyping technology, 3D fiber deposition (3DF). In this study, scaffolds with different structures were fabricated by changing fiber spacing and fiber orientation. The influence of different architectures on mechanical properties and permeability of the scaffold were investigated. Mechanical analysis revealed that compressive strength and E-modulus increase with decreasing the porosity. Permeability measurements showed that not only the total porosity but also the porous structure can influence the permeability. 3DF was found to provide good control and reproducibility of the desired degree of porosity and the 3D structure. Results of this study demonstrate that the 3DF of Ti6Al4V give us flexibility and versatility to fabricate and improve scaffolds to better mimic the architecture and properties of natural bone and meet the requirements of bone graft substitutes and orthopedic and dental implants! . PMID: 19165798 [PubMed - indexed for MEDLINE] | | |
| Enzymatically crosslinked porous composite matrices for bone tissue regeneration.
February 18, 2010 at 6:11 AM
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| | Enzymatically crosslinked porous composite matrices for bone tissue regeneration. J Biomed Mater Res A. 2010 Jan;92(1):137-51 Authors: Ciardelli G, Gentile P, Chiono V, Mattioli-Belmonte M, Vozzi G, Barbani N, Giusti P Three-dimensional porous hydroxyapatite/collagen (HA/Coll) composites with a random pore structure were obtained by freeze-drying and crosslinked by an enzymatic treatment using microbial transglutaminase (mTGase). The procedure resulted in improved mechanical strength and thermal stability of the scaffolds. The scaffolds were characterized in terms of their stability (Coll release, swelling, collagenase-mediated degradation), thermal properties (thermogravimetric analysis, differential scanning calorimetry), mechanical behavior under compression and cell compatibility. Enzymatic treatment stabilized the sponges to water vapors, with measurable swelling ratio between 100% for HA/Coll/mTGase 0/100 to 5% for HA/Coll/mTGase 80/20. Weight loss in water due to Coll release was between 2 and 10% in mTGase-crosslinked samples and decreased with increasing HA content. Cultures of MG63 osteoblast-like cells and human umbilical vein endothelial cells (HUVEC) showed good adh! esion and proliferation on the scaffolds, good viability (through MTT test, 100-150% of control), and good differentiation (alkaline phosphatase, up to 40 UI/L with respect to 35 UI/L for control). PMID: 19165785 [PubMed - indexed for MEDLINE] | | |
| Sorbitan monooleate and poly(L-lactide-co-epsilon-caprolactone) electrospun nanofibers for endothelial cell interactions.
February 18, 2010 at 6:11 AM
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| | Sorbitan monooleate and poly(L-lactide-co-epsilon-caprolactone) electrospun nanofibers for endothelial cell interactions. J Biomed Mater Res A. 2009 Dec;91(3):878-85 Authors: Li X, Su Y, He C, Wang H, Fong H, Mo X The aim of this study was to investigate electrospinning of emulsions to prepare core-shell type of nanofibers for being an innovative type of cell-growth scaffolds with potentially controllable drug-releasing capabilities. The hypothesis was that the poly(L-lactide-co-epsilon-caprolactone) [P(LLA-CL), shell] nanofibrous mats containing sorbitan monooleate (Span-80, core) could be appropriate scaffolds for growing pig iliac endothelium cells (PIECs). To test the hypothesis, the electrospinning of emulsions made of P(LLA-CL), chloroform, Span-80, and distilled water to prepare P(LLA-CL)/Span-80 nanofibers was systematically investigated. The effects of water content and P(LLA-CL) concentration in the emulsions on the morphologies of the nanofibers were studied. The morphologies, mechanical properties, and surface hydrophilicity of the nanofibrous mats were examined. The performance for being scaffolds was investigated by examination of the viability (anchorage and ! proliferation) and morphology of PIECs on the nanofibrous mats. There were no statistically significant differences in endothelial cell growth on the core-shell nanofibrous mats compared to the polymeric nanofibrous mats, and the P(LLA-CL)/Span-80 nanofiber mats could be used as an innovative type of scaffolds with potentially controllable drug-releasing capabilities. PMID: 19065570 [PubMed - indexed for MEDLINE] | | |
| Monocyte inflammatory and matrix remodeling response modulated by grafted ECM-derived ligand concentration.
February 18, 2010 at 6:11 AM
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| | Monocyte inflammatory and matrix remodeling response modulated by grafted ECM-derived ligand concentration. J Biomed Mater Res A. 2009 Dec;91(3):742-52 Authors: Chung AS, Waldeck H, Schmidt DR, Kao WJ Ligands presented on biomaterials are a common method to facilitate and control the host response. In a gelatin and polyethylene glycol diacrylate (PEGdA) based semi-interpenetrating network (sIPN), the effects of extracellular matrix (ECM)-derived peptide amount on monocyte adhesion and subsequent protein and mRNA expression were examined. Peptide amount on the sIPN surface was controlled by varying the wt % ratio of the peptide-PEG grafted gelatin to PEGdA. We hypothesized that increasing bioactive peptide amount would modulate human blood-derived monocyte adhesion, cytokine expression, and gene regulation. Monocyte adhesion, release of gelatin degrading proteases matrix metalloprotease-2 (MMP-2), matrix metalloprotease-9 (MMP-9), and proinflammatory protein interleukin-1beta (IL-1beta), and mRNA expression of these proteins were evaluated. We found RGD-PEG grafted sIPNs with higher surface RGD concentrations showed increased adherent density. MMP-2 and IL-1beta! protein release was also influenced by the ligand concentration, as initial increase in protein concentration was observed at higher ligand concentrations. MMP-9 protein showed an initial increase that subsided then increased. A decreased IL-1beta protein and mRNA expression was observed over time but MMP-2 mRNA was not detected at any time though MMP-2 protein concentrations showed an initial burst. Hence, monocyte behavior was modulated by surface ligand identity in tandem with ligand concentration. PMID: 19051303 [PubMed - indexed for MEDLINE] | | |
| Genipin enhances the mechanical properties of tissue-engineered cartilage and protects against inflammatory degradation when used as a medium supplement.
February 18, 2010 at 6:11 AM
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| | Genipin enhances the mechanical properties of tissue-engineered cartilage and protects against inflammatory degradation when used as a medium supplement. J Biomed Mater Res A. 2009 Dec;91(3):692-700 Authors: Lima EG, Tan AR, Tai T, Marra KG, DeFail A, Ateshian GA, Hung CT Genipin is a naturally-derived biocompatible cross-linking agent commonly used to generate three dimensional tissue-engineered scaffolds or to fix biologically derived scaffolds prior to implantation. Here we propose a novel use for genipin as a long-term culture medium supplement to promote cross-linking of de novo cell products that are produced in engineered cartilage. We hypothesize that the application of genipin will stabilize the extracellular matrix components and increase the mechanical properties of developing engineered cartilage. Chondrocytes encapsulated in agarose hydrogel (a neutrally charged polysaccharide scaffold that is unaffected by genipin cross-linking) were cultured in a chemically-defined growth medium that was supplemented with varying concentrations of genipin (22 microM, 220 microM, 2200 microM) for various durations (continuous or intermittent). Tissues developed significantly higher mechanical properties (+28% dynamic modulus and +20% ! Young's modulus) by day 42 with genipin treatment compared to untreated controls. These increases were not immediate, but presented over culture time after genipin treatment. The genipin treated groups were also more resistant to cytokine-induced degradation with interleukin-1alpha; maintaining an E(Y) (+218%), G* (+390%) and glycosaminoglycan (GAG) content (+477%) over genipin-untreated constructs subjected to interleukin. We hypothesize two mechanisms through which the physical enhancement of tissue properties may be fostered: (1) by cross-link mediated reorganization and enhanced retention of cell-elaborated extracellular matrix components, and (2) through reduction of the loss of extracellular matrix components by increasing their resilience to catabolic degradation. These studies demonstrate a potential use of genipin as a medium supplement to develop enhanced engineered cartilage. PMID: 19025982 [PubMed - indexed for MEDLINE] | | |
| Solid freeform fabrication and characterization of porous calcium polyphosphate structures for tissue engineering purposes.
February 18, 2010 at 6:11 AM
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| | Solid freeform fabrication and characterization of porous calcium polyphosphate structures for tissue engineering purposes. J Biomed Mater Res B Appl Biomater. 2010 Feb 16; Authors: Shanjani Y, De Croos JN, Pilliar RM, Kandel RA, Toyserkani E Solid freeform fabrication (SFF) enables the fabrication of anatomically shaped porous components required for formation of tissue engineered implants. This article reports on the characterization of a three-dimensional-printing method, as a powder-based SFF technique, to create reproducible porous structures composed of calcium polyphosphate (CPP). CPP powder of 75-150 mum was mixed with 10 wt % polyvinyl alcohol (PVA) polymeric binder, and used in the SFF machine with appropriate settings for powder mesh size. The PVA binder was eliminated during the annealing procedure used to sinter the CPP particles. The porous SFF fabricated components were characterized using scanning electron microscopy, micro-CT scanning, X-ray diffraction, and mercury intrusion porosimetry. In addition, mechanical testing was conducted to determine the compressive strength of the CPP cylinders. The 35 vol % porous structures displayed compressive strength on average of 33.86 MPa, a value! 57% higher than CPP of equivalent volume percent porosity made through conventional gravity sintering. Dimensional deviation and shrinkage analysis was conducted to identify anisotropic factors required for dimensional compensation during SFF sample formation and subsequent sintering. Cell culture studies showed that the substrate supported cartilage formation in vitro, which was integrated with the top surface of the porous CPP similar to that observed when chondrocytes were grown on CPP formed by conventional gravity sintering methods as determined histologically and biochemically. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20162726 [PubMed - as supplied by publisher] | | |
| Progenitor Cells for Regenerative Medicine and Consequences of ART and Cloning-Associated Epimutations.
February 18, 2010 at 6:11 AM
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| | Progenitor Cells for Regenerative Medicine and Consequences of ART and Cloning-Associated Epimutations. Mol Biotechnol. 2010 Feb 17; Authors: Laprise SL The "holy grail" of regenerative medicine is the identification of an undifferentiated progenitor cell that is pluripotent, patient specific, and ethically unambiguous. Such a progenitor cell must also be able to differentiate into functional, transplantable tissue, while avoiding the risks of immune rejection. With reports detailing aberrant genomic imprinting associated with assisted reproductive technologies (ART) and reproductive cloning, the idea that human embryonic stem cells (hESCs) derived from surplus in vitro fertilized embryos or nuclear transfer ESCs (ntESCs) harvested from cloned embryos may harbor dangerous epigenetic errors has gained attention. Various progenitor cell sources have been proposed for human therapy, from hESCs to ntESCs, and from adult stem cells to induced pluripotent stem cells (iPS and piPS cells). This review highlights the advantages and disadvantages of each of these technologies, with particular emphasis on epigenetic stabilit! y. PMID: 20162468 [PubMed - as supplied by publisher] | | |
| AAA Stent-Grafts: Past Problems and Future Prospects.
February 18, 2010 at 6:11 AM
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| | AAA Stent-Grafts: Past Problems and Future Prospects. Ann Biomed Eng. 2010 Feb 17; Authors: Desai M, Eaton-Evans J, Hillery C, Bakhshi R, You Z, Lu J, Hamilton G, Seifalian AM Endovascular aneurysm repair (EVAR) has quickly gained popularity for infrarenal abdominal aortic aneurysm repair during the last two decades. The improvement of available EVAR devices is critical for the advancement of patient care in vascular surgery. Problems are still associated with the grafts, many of which can necessitate the conversion of the patient to open repair, or even result in rupture of the aneurysm. This review attempts to address these problems, by highlighting why they occur and what the failings of the currently available stent grafts are, respectively. In addition, the review gives critical appraisal as to the novel methods required for dealing with these problems and identifies the new generation of stent grafts that are being or need to be designed and constructed in order to overcome the issues that are associated with the existing first- and second-generation devices. PMID: 20162359 [PubMed - as supplied by publisher] | | |
| Maintaining cell depth viability: on the efficacy of a trimodal scaffold pore architecture and dynamic rotational culturing.
February 18, 2010 at 6:11 AM
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| | Maintaining cell depth viability: on the efficacy of a trimodal scaffold pore architecture and dynamic rotational culturing. J Mater Sci Mater Med. 2010 Feb 17; Authors: Buckley CT, O'Kelly KU Tissue-engineering scaffold-based strategies have suffered from limited cell depth viability when cultured in vitro with viable cells typically existing at the fluid-scaffold interface. This is primarily believed to be due to the lack of nutrient delivery into and waste removal from the inner regions of the scaffold construct. This work focused on the assessment of a hydroxyapatite multi-domain porous scaffold architecture (i.e. a scaffold providing a discrete domain for cell occupancy and a separate domain for nutrient delivery). It has been demonstrated that incorporating unidirectional channels into a porous scaffold material significantly enhanced initial cell seeding distribution, while maintaining relatively high seeding efficiencies. In vitro static culturing showed that providing a discrete domain for nutrient diffusion and metabolic waste removal is insufficient to enhance or maintain homogeneous cell viability throughout the entire scaffold depth during ! a 7-day culture period. In contrast, scaffolds subjected to dynamic rotational culturing maintained uniform cell viability throughout the scaffold depth with increasing culturing time and enhanced the extent of cell proliferation (~2-2.4-fold increase) compared to static culturing. PMID: 20162335 [PubMed - as supplied by publisher] | | |
| Bioglass as a carrier for reindeer bone protein extract in the healing of rat femur defect.
February 18, 2010 at 6:11 AM
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| | Bioglass as a carrier for reindeer bone protein extract in the healing of rat femur defect. J Mater Sci Mater Med. 2010 Feb 17; Authors: Tölli H, Kujala S, Levonen K, Jämsä T, Jalovaara P Bioactive glasses have been developed as scaffolds for bone tissue engineering but combination with reindeer bone protein extract has not been evaluated. We investigated the effects of bone protein extract implants (5-40 mg dosages) with bioglass (BG) carrier on the healing of rat femur defects. Bioglass implants and untreated defects served as controls. All doses of extract increased bone formation compared with the control groups, and bone union was enhanced with doses of 10 mg or more. In comparison with untreated defect, mean cross-sectional bone area at the defect site was greater when implants with BG + 15 mg of extract or bioglass alone were used, bone density at the defect site was higher in all bioglass groups with and without bone extract, and the BG + 15 mg extract dosage marginally increased bone torsional stiffness in mechanical testing. Bioglass performed well as a carrier candidate for reindeer bone protein extract. PMID: 20162331 [PubMed - as supplied by publisher] | | |
| Glycine-spacers influence functional motifs exposure and self-assembling propensity of functionalized substrates tailored for neural stem cell cultures.
February 18, 2010 at 6:11 AM
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| | Glycine-spacers influence functional motifs exposure and self-assembling propensity of functionalized substrates tailored for neural stem cell cultures. Front Neuroengineering. 2010;3:1 Authors: Taraballi F, Natalello A, Campione M, Villa O, Doglia SM, Paleari A, Gelain F The understanding of phenomena involved in the self-assembling of bio-inspired biomaterials acting as three-dimensional scaffolds for regenerative medicine applications is a necessary step to develop effective therapies in neural tissue engineering. We investigated the self-assembled nanostructures of functionalized peptides featuring four, two or no glycine-spacers between the self-assembly sequence RADA16-I and the functional biological motif PFSSTKT. The effectiveness of their biological functionalization was assessed via in vitro experiments with neural stem cells (NSCs) and their molecular assembly was elucidated via atomic force microscopy, Raman and Fourier Transform Infrared spectroscopy. We demonstrated that glycine-spacers play a crucial role in the scaffold stability and in the exposure of the functional motifs. In particular, a glycine-spacer of four residues leads to a more stable nanostructure and to an improved exposure of the functional motif. Acco! rdingly, the longer spacer of glycines, the more effective is the functional motif in both eliciting NSCs adhesion, improving their viability and increasing their differentiation. Therefore, optimized designing strategies of functionalized biomaterials may open, in the near future, new therapies in tissue engineering and regenerative medicine. PMID: 20162033 [PubMed - in process] | | |
| Bridging the Divide between Neuroprosthetic Design, Tissue Engineering and Neurobiology.
February 18, 2010 at 6:11 AM
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| | Bridging the Divide between Neuroprosthetic Design, Tissue Engineering and Neurobiology. Front Neuroengineering. 2010;2:18 Authors: Leach JB, Achyuta AK, Murthy SK Neuroprosthetic devices have made a major impact in the treatment of a variety of disorders such as paralysis and stroke. However, a major impediment in the advancement of this technology is the challenge of maintaining device performance during chronic implantation (months to years) due to complex intrinsic host responses such as gliosis or glial scarring. The objective of this review is to bring together research communities in neurobiology, tissue engineering, and neuroprosthetics to address the major obstacles encountered in the translation of neuroprosthetics technology into long-term clinical use. This article draws connections between specific challenges faced by current neuroprosthetics technology and recent advances in the areas of nerve tissue engineering and neurobiology. Within the context of the device-nervous system interface and central nervous system implants, areas of synergistic opportunity are discussed, including platforms to present cells with! multiple cues, controlled delivery of bioactive factors, three-dimensional constructs and in vitro models of gliosis and brain injury, nerve regeneration strategies, and neural stem/progenitor cell biology. Finally, recent insights gained from the fields of developmental neurobiology and cancer biology are discussed as examples of exciting new biological knowledge that may provide fresh inspiration toward novel technologies to address the complexities associated with long-term neuroprosthetic device performance. PMID: 20161810 [PubMed - in process] | | |
| Biomedical applications of chemically-modified silk fibroin.
February 18, 2010 at 6:11 AM
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| | Biomedical applications of chemically-modified silk fibroin. J Mater Chem. 2009 Jun 23;19(36):6443-6450 Authors: Murphy AR, Kaplan DL Silk proteins belong to a class of unique, high molecular weight, block copolymer-like proteins that have found widespread use in biomaterials and regenerative medicine. The useful features of these proteins, including self-assembly, robust mechanical properties, biocompatibility and biodegradability can be enhanced through a variety of chemical modifications. These modifications provide chemical handles for the attachment of growth factors, cell binding domains and other polymers to silk, expanding the range of cell and tissue engineering applications attainable. This review focuses on the chemical reactions that have been used to modify the amino acids in silk proteins, and describes their utility in biomedical applications. PMID: 20161439 [PubMed - as supplied by publisher] | | |
| Biodegradable Fibrous Scaffolds with Tunable Properties Formed from Photocrosslinkable Poly(glycerol sebacate).
February 18, 2010 at 6:11 AM
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| | Biodegradable Fibrous Scaffolds with Tunable Properties Formed from Photocrosslinkable Poly(glycerol sebacate). ACS Appl Mater Interfaces. 2009 Sep 30;1(9):1878-1892 Authors: Ifkovits JL, Devlin JJ, Eng G, Martens TP, Vunjak-Novakovic G, Burdick JA It is becoming increasingly apparent that the architecture and mechanical properties of scaffolds, particularly with respect to mimicking features of natural tissues, are important for tissue engineering applications. Acrylated poly(glycerol sebacate) (Acr-PGS) is a material that can be crosslinked upon exposure to ultraviolet light, leading to networks with tunable mechanical and degradation properties through simple changes during Acr-PGS synthesis. For example, the number of acrylate functional groups on the macromer dictates the concentration of crosslinks formed in the resulting network. Three macromers were synthesized that form networks that vary dramatically with respect to their tensile modulus (~30 kPa to 6.6 MPa) and degradation behavior (~20 to 100% mass loss at 12 weeks) based on the extent of acrylation (~1 to 24%). These macromers were processed into biodegradable fibrous scaffolds using electrospinning, with gelatin as a carrier polymer to facilita! te fiber formation and cell adhesion. The resulting scaffolds were also diverse with respect to their mechanics (tensile modulus ranging from ~60 kPa to 1 MPa) and degradation (~45 to 70% mass loss by 12 weeks). Mesenchymal stem cell adhesion and proliferation on all fibrous scaffolds was indistinguishable from controls. The scaffolds showed similar diversity when implanted on the surface of hearts in a rat model of acute myocardial infarction and demonstrated a dependence on scaffold thickness and chemistry in the host response. In summary, these diverse scaffolds with tailorable chemical, structural, mechanical and degradation properties are potentially useful for the engineering of a wide range of soft tissues. PMID: 20160937 [PubMed - as supplied by publisher] | | |
| The future: optimizing the healing environment in anterior cruciate ligament reconstruction.
February 18, 2010 at 6:11 AM
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| | The future: optimizing the healing environment in anterior cruciate ligament reconstruction. Sports Med Arthrosc. 2010 Mar;18(1):48-53 Authors: Sánchez M, Anitua E, Lopez-Vidriero E, Andía I The therapeutic use of autologous platelet-rich plasma constitutes a breakthrough in the stimulation and acceleration of soft-tissue healing and bone regeneration. Platelet-rich technologies seek to facilitate anterior cruciate ligament replacement by mimicking the native tissue and improving the adequacy of tissue function with appropriate cues, ultimately leading to better patient care. There are different technical protocols for preparing platelet-rich plasma, and the resultant products are typically heterogeneous; moreover, protocols for administrating the products in patients vary extensively. Poor standardization in the field makes full evaluation of different plasma products and establishing standards for the most beneficial applications of this technology difficult. This article presents the current data on the use of platelet-rich plasma in the reconstruction of the anterior cruciate ligament. Although the findings are not conclusive, the use of autologou! s platelet-rich plasma is shown to be safe, reproducible, and effective in mimicking the natural processes of soft tissue and bone healing. Platelet-rich technologies offer new opportunities for research and the application of anterior cruciate ligament tissue engineering. PMID: 20160631 [PubMed - in process] | | |
| Human iPS cell-based therapy: Considerations before clinical applications.
February 18, 2010 at 6:11 AM
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| | Human iPS cell-based therapy: Considerations before clinical applications. Cell Cycle. 2010 Mar 2;9(5) Authors: Sun N, Longaker MT, Wu JC Generation of induced pluripotent stem (iPS) cells has revolutionized the field of regenerative medicine. With the exponential increase in iPS cell research in the past three years, human iPS cells have been derived with different technologies and from various cell types. From a translational perspective, however, a number of issues must be addressed before safe and high quality patient-specific iPS cells can be derived for clinical applications. In addition, iPS cell-based therapies also need to be thoroughly evaluated in pre-clinical animal models before they can be applied to human subjects. PMID: 20160515 [PubMed - as supplied by publisher] | | |
| Active multilayered capsules for in vivo bone formation.
February 18, 2010 at 6:11 AM
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| | Active multilayered capsules for in vivo bone formation. Proc Natl Acad Sci U S A. 2010 Feb 16; Authors: Facca S, Cortez C, Mendoza-Palomares C, Messadeq N, Dierich A, Johnston AP, Mainard D, Voegel JC, Caruso F, Benkirane-Jessel N Interest in the development of new sources of transplantable materials for the treatment of injury or disease has led to the convergence of tissue engineering with stem cell technology. Bone and joint disorders are expected to benefit from this new technology because of the low self-regenerating capacity of bone matrix secreting cells. Herein, the differentiation of stem cells to bone cells using active multilayered capsules is presented. The capsules are composed of poly-L-glutamic acid and poly-L-lysine with active growth factors embedded into the multilayered film. The bone induction from these active capsules incubated with embryonic stem cells was demonstrated in vitro. Herein, we report the unique demonstration of a multilayered capsule-based delivery system for inducing bone formation in vivo. This strategy is an alternative approach for in vivo bone formation. Strategies using simple chemistry to control complex biological processes would be particularly p! owerful, as they make production of therapeutic materials simpler and more easily controlled. PMID: 20160118 [PubMed - as supplied by publisher] | | |
| Caspase 3/caspase-activated DNase promote cell differentiation by inducing DNA strand breaks.
February 18, 2010 at 6:11 AM
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| | Caspase 3/caspase-activated DNase promote cell differentiation by inducing DNA strand breaks. Proc Natl Acad Sci U S A. 2010 Feb 16; Authors: Larsen BD, Rampalli S, Burns LE, Brunette S, Dilworth FJ, Megeney LA Caspase 3 is required for the differentiation of a wide variety of cell types, yet it remains unclear how this apoptotic protein could promote such a cell-fate decision. Caspase signals often result in the activation of the specific nuclease caspase-activated DNase (CAD), suggesting that cell differentiation may be dependent on a CAD-mediated modification in chromatin structure. In this study, we have investigated if caspase 3/CAD plays a role in initiating the DNA strand breaks that are known to occur during the terminal differentiation of skeletal muscle cells. Here, we show that inhibition of caspase 3 or reduction of CAD expression leads to a dramatic loss of strand-break formation and a block in the myogenic program. Caspase-dependent induction of differentiation results in CAD targeting of the p21 promoter, and loss of caspase 3 or CAD leads to a significant down-regulation in p21 expression. These results show that caspase 3/CAD promotes cell differentiatio! n by directly modifying the DNA/nuclear microenvironment, which enhances the expression of critical regulatory genes. PMID: 20160104 [PubMed - as supplied by publisher] | | |
| Apatite Containing Aspartic Acid for Selective Protein Loading.
February 18, 2010 at 6:11 AM
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| | Apatite Containing Aspartic Acid for Selective Protein Loading. J Dent Res. 2010 Feb 16; Authors: Hafiz Uddin M, Matsumoto T, Ishihara S, Nakahira A, Okazaki M, Sohmura T Physico-chemical modifications of hydroxyapatite (HAp) materials are considered as pre-requisites for the development of new bioactive carrier materials for drug delivery and tissue engineering applications. Since acidic amino acids have well-documented affinities to both HAp and basic proteins, HAp modified by aspartic acid (Asp, acidic amino acid) might be one of the candidate substrates for a basic protein carrier. Here, we synthesized HAp in the presence of various concentrations of Asp and observed that HAp crystallinity and other physico-chemical properties were effectively modulated. Detailed studies indicated that Asp was not incorporated in the HAp crystal lattice, but rather was trapped in HAp crystals. Protein adsorption studies indicated that the HAp particles modified by Asp had a selective loading capacity for basic protein. Therefore, HAp particles containing Asp might have potential in drug delivery applications, especially as the carrier of basic ! proteins including bFGF and BMP. PMID: 20160067 [PubMed - as supplied by publisher] | | |
| Regenerative Medicine for Craniomaxillofacial Surgery.
February 18, 2010 at 6:11 AM
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| | Regenerative Medicine for Craniomaxillofacial Surgery. Oral Maxillofac Surg Clin North Am. 2010 Feb;22(1):33-42 Authors: Costello BJ, Shah G, Kumta P, Sfeir CS Regenerative medicine has recently seen much activity in basic and translational research. These advances are now making their way into surgical practice. A convergence of technologies has afforded opportunities previously not available with conventional surgical reconstructive techniques. Patients requiring complex reconstructive surgery in the craniomaxillofacial region typically benefit from local or regional flaps, nonvascularized grafts, microvascular tissue transfer, or substitute alloplastic materials to restore function and form. In these clinical situations, grafting procedures or alloplastic substitute materials provide best-case replacements for resected, injured, or congenitally missing tissues. However, ideal reconstructive goals, such as a complete return to original form and function, are frequently not completely achieved. Regenerative techniques now in clinical use and at the translational research stage hold promise for custom-tailored constructs! with the potential to regenerate tissue in the host without significant donor site morbidity. These techniques may provide better structure, aesthetics, and function than the best currently available options. This article presents the latest concepts in craniomaxillofacial regenerative medicine and reviews the multipronged approach to restoring architecture using novel "smart" multifunctional scaffolds, cellular technologies, growth factors, and other novel regenerative medical strategies. PMID: 20159476 [PubMed - as supplied by publisher] | | |
| Cord blood: the future of regenerative medicine?
February 18, 2010 at 6:11 AM
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| | Cord blood: the future of regenerative medicine? Reprod Biomed Online. 2010 Jan;20(1):98-102 Authors: Seres KB, Hollands P Cord blood stem cells have been in routine clinical practice for the past 20 years. The development of new therapeutic protocols in regenerative medicine require the use of stem cells and umbilical cord blood is an important and readily available source of cells for these applications. The latest concepts in routine transplantation of cord blood are reviewed followed by the critical role of cord blood stem cells in regenerative medicine research and novel approaches using cord blood as a source of whole blood for transfusion. PMID: 20158994 [PubMed - as supplied by publisher] | | |
| Interferon Beta Modulates Endothelial Damage in Patients with Cardiac Persistence of Human Parvovirus B19 Infection.
February 18, 2010 at 6:11 AM
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| | Interferon Beta Modulates Endothelial Damage in Patients with Cardiac Persistence of Human Parvovirus B19 Infection. J Infect Dis. 2010 Feb 16; Authors: Schmidt-Lucke C, Spillmann F, Bock T, Kühl U, Van Linthout S, Schultheiss HP, Tschöpe C Background. In a phase 1 study, we investigated whether interferon beta reduced endothelial damage in patients with cardiac persistence of human parvovirus B19 (B19V) infection. Methods and results. In vitro, B19V infected cultivated endothelial cells (ECs), which led to a reduction in their viability ([Formula: see text]). Interferon beta suppressed B19V replication by 63% ([Formula: see text]) in ECs and increased their viability ([Formula: see text]). Circulating mature apoptotic ECs (CMAECs [CD45(-)CD146(+) cells expressing von Willebrand factor and annexin V]) and circulating progenitor cells (CPCs [CD34(+)KDR(+) cells]) were quantified by flow cytometry in 9 symptomatic patients with cardiac B19V infection before and after 6 months of interferon beta therapy (16 MU) and were compared to levels in 9 healthy control subjects. Endothelial dysfunction was measured using flow-mediated dilatation of the forearm. Patients with B19V persistence had significantly hig! her ([Formula: see text]) levels of CMAECs than did control subjects, which normalized after treatment (mean +/- standard deviation, [Formula: see text] vs [Formula: see text]; [Formula: see text]). Similar improvement was shown for flow-mediated dilatation ([Formula: see text]) in the treatment group only ([Formula: see text] for the comparison with untreated patients with B19V persistence [[Formula: see text]]). There were significantly higher numbers of CPCs in patients with B19V persistence before therapy (mean +/- standard deviation, [Formula: see text] vs [Formula: see text]; [Formula: see text]) than in control subjects, which normalized after treatment ([Formula: see text]). Conclusion. Thus, we present (for the first time, to our knowledge) a modulation of virally induced chronic endothelial damage-specifically, EC apoptosis and endothelial regeneration. PMID: 20158391 [PubMed - as supplied by publisher] | | |
| Biomimetic Branched Hollow Fibers Templated by Self-Assembled Fibrous Polyvinylpyrrolidone Structures in Aqueous Solution.
February 18, 2010 at 6:11 AM
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| | Biomimetic Branched Hollow Fibers Templated by Self-Assembled Fibrous Polyvinylpyrrolidone Structures in Aqueous Solution. ACS Nano. 2010 Feb 16; Authors: Qiu P, Mao C Branched hollow fibers are common in nature, but to form artificial fibers with a similar branched hollow structure is still a challenge. We discovered that polyvinylpyrrolidone (PVP) could self-assemble into branched hollow fibers in an aqueous solution after aging the PVP solution for about two weeks. On the basis of this finding, we demonstrated two approaches by which the self-assembly of PVP into branched hollow fibers could be exploited to template the formation of branched hollow inorganic fibers. First, inorganic material such as silica with high affinity against the PVP could be deposited on the surface of the branched hollow PVP fibers to form branched hollow silica fibers. To extend the application of PVP self-assembly in templating the formation of hollow branched fibers, we then adopted a second approach where the PVP molecules bound to inorganic nanoparticles (using gold nanoparticles as a model) co-self-assemble with the free PVP molecules in an aqu! eous solution, resulting in the formation of the branched hollow fibers with the nanoparticles embedded in the PVP matrix constituting the walls of the fibers. Heating the resultant fibers above the glass transition temperature of PVP led to the formation of branched hollow gold fibers. Our work suggests that the self-assembly of the PVP molecules in the solution can serve as a general method for directing the formation of branched hollow inorganic fibers. The branched hollow fibers may find potential applications in microfluidics, artificial blood vessel generation, and tissue engineering. PMID: 20158250 [PubMed - as supplied by publisher] | | |
| Self-Assembling Multidomain Peptide Hydrogels: Designed Susceptibility to Enzymatic Cleavage Allows Enhanced Cell Migration and Spreading.
February 18, 2010 at 6:11 AM
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| | Self-Assembling Multidomain Peptide Hydrogels: Designed Susceptibility to Enzymatic Cleavage Allows Enhanced Cell Migration and Spreading. J Am Chem Soc. 2010 Feb 16; Authors: Galler KM, Aulisa L, Regan KR, D'Souza RN, Hartgerink JD Multidomain peptides are a class of amphiphilic self-assembling peptides with a modular ABA block motif in which the amphiphilic B block drives self-assembly while the flanking A blocks, which are electrostatically charged, control the conditions under which assembly takes place. Previously we have shown that careful selection of the amino acids in the A and B blocks allow one to control the self-assembled fiber length and viscoelastic properties of formed hydrogels. Here we demonstrate how the modular nature of this peptide assembler can be designed for biological applications. With control over fiber length and diameter, gelation conditions, and viscoelastic properties, we can develop suitable materials for biological applications. Going beyond a simple carrier for cell delivery, a biofunctional scaffold will interact with the cells it carries, promoting advantageous cell-matrix interactions. We demonstrate the design of a multidomain peptide into a bioactive va! riant by incorporation of a matrix metalloprotease 2 (MMP-2) specific cleavage site and cell adhesion motif. Gel formation and rheological properties were assessed and compared to related peptide hydrogels. Proteolytic degradation by collagenase IV was observed in a gel weight loss study and confirmed by specific MMP-2 degradation monitored by mass spectrometry and cryo-transmission electron microscopy (cryo-TEM). Combination of this cleavage site with the cell adhesion motif RGD resulted in increased cell viability and cell spreading and encouraged cell migration into the hydrogel matrix. Collectively the structural, mechanical, and bioactive properties of this multidomain peptide hydrogel make it suitable as an injectable material for a variety of tissue engineering applications. PMID: 20158218 [PubMed - as supplied by publisher] | | |
| Microfluidic Assays for DNA Manipulation Based on a Block Copolymer Immobilization Strategy.
February 18, 2010 at 6:11 AM
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| | Microfluidic Assays for DNA Manipulation Based on a Block Copolymer Immobilization Strategy. Biomacromolecules. 2010 Feb 16; Authors: Vasdekis AE, O'Neil CP, Hubbell JA, Psaltis D Methods to manipulate and visualize isolated DNA and oligonucleotide strands are important for investigation of their biophysics as well as their interactions with proteins. Herein, we report such a method by combining a block copolymer surface functionalization strategy with microfluidics. The copolymer poly(l-lysine-graft-polyethylene glycol) (PLL-g-PEG) coated one surface of the microfluidic channels, rendering it passive to adsorption and thus minimizing any noise arising from nontargeted adsorbed molecules. Single lambda-phage DNA molecules were immobilized and were extended by molecular combing. Their extension did not exceed their contour length, which we attribute to the low surface tension of the coated surface. To demonstrate further the applicability of our method, the anchored DNA was extended by hydrodynamic flow. We propose this method for exploring DNA-protein interactions due to the copolymer's enhanced capacity for single-molecule detection, stabi! lity under wet or dry conditions, hydrophilicity, full compatibility with microfluidics and simplicity being a one-step process. PMID: 20158193 [PubMed - as supplied by publisher] | | |
| DNMT1 maintains progenitor function in self-renewing somatic tissue.
February 18, 2010 at 6:11 AM
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| | DNMT1 maintains progenitor function in self-renewing somatic tissue. Nature. 2010 Jan 28;463(7280):563-7 Authors: Sen GL, Reuter JA, Webster DE, Zhu L, Khavari PA Progenitor cells maintain self-renewing tissues throughout life by sustaining their capacity for proliferation while suppressing cell cycle exit and terminal differentiation. DNA methylation provides a potential epigenetic mechanism for the cellular memory needed to preserve the somatic progenitor state through repeated cell divisions. DNA methyltransferase 1 (DNMT1) maintains DNA methylation patterns after cellular replication. Although dispensable for embryonic stem cell maintenance, the role for DNMT1 in maintaining the progenitor state in constantly replenished somatic tissues, such as mammalian epidermis, is unclear. Here we show that DNMT1 is essential for epidermal progenitor cell function. DNMT1 protein was found enriched in undifferentiated cells, where it was required to retain proliferative stamina and suppress differentiation. In tissue, DNMT1 depletion led to exit from the progenitor cell compartment, premature differentiation and eventual tissue loss! . Genome-wide analysis showed that a significant portion of epidermal differentiation gene promoters were methylated in self-renewing conditions but were subsequently demethylated during differentiation. Furthermore, UHRF1 (refs 9, 10), a component of the DNA methylation machinery that targets DNMT1 to hemi-methylated DNA, is also necessary to suppress premature differentiation and sustain proliferation. In contrast, Gadd45A and B, which promote active DNA demethylation, are required for full epidermal differentiation gene induction. These data demonstrate that proteins involved in the dynamic regulation of DNA methylation patterns are required for progenitor maintenance and self-renewal in mammalian somatic tissue. PMID: 20081831 [PubMed - indexed for MEDLINE] | | |
| Flk-1+ mesenchymal stem cells aggravate collagen-induced arthritis by up-regulating interleukin-6.
February 18, 2010 at 6:11 AM
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| | Flk-1+ mesenchymal stem cells aggravate collagen-induced arthritis by up-regulating interleukin-6. Clin Exp Immunol. 2010 Mar;159(3):292-302 Authors: Chen B, Hu J, Liao L, Sun Z, Han Q, Song Z, Zhao RC The immunomodulatory ability of mesenchymal stem cells (MSCs) may be used to develop therapies for autoimmune diseases. Flk-1(+) MSCs are a population of MSCs with defined phenotype and their safety has been evaluated in Phase 1 clinical trials. We designed this study to evaluate whether Flk-1(+) MSCs conferred a therapeutic effect on collagen-induced arthritis (CIA), an animal model of rheumatic arthritis, and to explore the underlying mechanisms. Flk-1(+) MSCs, 1-2 x 10(6), were injected into CIA mice on either day 0 or day 21. The clinical course of arthritis was monitored. Serum cytokine profile was determined by cytometric bead array kit or enzyme-linked immunosorbent assay. Flk-1(+) MSCs and splenocytes co-culture was conducted to explore the underlying mechanisms. Flk-1(+) MSCs did not confer therapeutic benefits. Clinical symptom scores and histological evaluation suggested aggravation of arthritis in mice treated with MSCs at day 21. Serum cytokine profil! e analysis showed marked interleukin (IL)-6 secretion immediately after MSC administration. Results of in vitro culture of splenocytes confirmed that the addition of Flk-1(+) MSCs promoted splenocyte proliferation and increased IL-6 and IL-17 secretion. Moreover, splenocyte proliferation was also enhanced in mice treated with MSCs at day 21. Accordingly, MSCs at low concentrations were found to promote lipopolysaccharide-primed splenocytes proliferation in an in vitro co-culture system. We propose that Flk-1(+) MSCs aggravate arthritis in CIA model by at least up-regulating secretion of IL-6, which favours Th17 differentiation. When Flk-1(+) MSCs are used for patients, we should be cautious about subjects with rheumatoid arthritis. PMID: 20002448 [PubMed - indexed for MEDLINE] | | |
| Cardiac and vascular functions of the zebrafish orthologues of the type I neurofibromatosis gene NFI.
February 18, 2010 at 6:11 AM
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| | Cardiac and vascular functions of the zebrafish orthologues of the type I neurofibromatosis gene NFI. Proc Natl Acad Sci U S A. 2009 Dec 29;106(52):22305-10 Authors: Padmanabhan A, Lee JS, Ismat FA, Lu MM, Lawson ND, Kanki JP, Look AT, Epstein JA Von Recklinghausen neurofibromatosis is a common autosomal dominant genetic disorder characterized by benign and malignant tumors of neural crest origin. Significant progress in understanding the pathophysiology of this disease has occurred in recent years, largely aided by the development of relevant animal models. Von Recklinghausen neurofibromatosis is caused by mutations in the NF1 gene, which encodes neurofibromin, a large protein that modulates the activity of Ras. Here, we describe the identification and characterization of zebrafish nf1a and nf1b, orthologues of NF1, and show neural crest and cardiovascular defects resulting from morpholino knockdown, including vascular and cardiac valvular abnormalities. Development of a zebrafish model of von Recklinghausen neurofibromatosis will allow for structure-function analysis and genetic screens in this tractable vertebrate system. PMID: 19966217 [PubMed - indexed for MEDLINE] | | |
| Prolactin induces MAPK signaling in neural progenitors without alleviating glucocorticoid-induced inhibition of in vitro neurogenesis.
February 18, 2010 at 6:11 AM
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| | Prolactin induces MAPK signaling in neural progenitors without alleviating glucocorticoid-induced inhibition of in vitro neurogenesis. Cell Physiol Biochem. 2009;24(5-6):397-406 Authors: Wagner K, Couillard-Despres S, Lehner B, Brockhoff G, Rivera FJ, Blume A, Neumann I, Aigner L We recently demonstrated that prolactin (PRL) prevents chronic stress-induced inhibition of adult hippocampal neurogenesis. It remained unsettled, however, whether PRL is acting directly on neural stem and progenitors cells (NPCs) or if neurogenesis is affected by an indirect mechanism, for example through the extensively described effects of PRL on the HPA axis. To address this point, we used neurosphere cultures derived from the adult rat hippocampus as an in vitro model for NPCs. Dexamethasone (DEX) was applied to stress the NPCs, and proliferation, survival and differentiation of cells were examined. DEX markedly inhibited proliferation of NPCs and cells entered the G(0) phase of cell cycle. Moreover, DEX reduced NPC survival and repressed astroglial differentiation, which is normally induced by serum or bone morphogenetic protein application. Even though we could demonstrate that NPCs express the PRL receptor and ERK1/2 signaling is induced by PRL, we did not! observe any effect of PRL on NPCs proliferation, differentiation or survival, neither in the presence nor during absence of DEX. In summary, our results indicate that PRL action on NPCs and neurogenesis in vivo occurs via an indirect mechanism. PMID: 19910680 [PubMed - indexed for MEDLINE] | | | | 
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