| |  | | | | | | | | | | | | | | | |  | | | | | | | | | | | | | | | | | | | | | | | | Adipose-derived stem and stromal cells for cell-based therapy: Current status of preclinical studies and clinical trials. Curr Opin Mol Ther. 2010 Aug;12(4):442-9 Authors: Mizuno H The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs offers a paradigm shift that may provide alternative therapeutic solutions for several diseases. The clinical use of either embryonic stem cells or induced pluripotent stem cells remains limited because of cell regulations, ethical considerations and the requirement for genetic manipulation, although these cells are theoretically highly beneficial. Adipose-derived stem cells (ASCs) appear to be an ideal population of stem cells for practical regenerative medicine, given that they are plentiful, of autologous tissue origin and thus non-immunogenic, and are more easily available because of minimal ethical considerations. Although ASCs originate from mesodermal lineages, recent preclinical studies have demonstrated that the use of ASCs in regenerative medicine is not limited to mesodermal tissue, but can also extend to both exodermal and endodermal tissues and organs. This review summarizes and discusses current preclinical and clinical data on the use of ASCs in regenerative medicine and discusses the future applications of such cell-based therapies. PMID: 20677095 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The expansion of human ES and iPS cells on porous membranes and proliferating human adipose-derived feeder cells. Biomaterials. 2010 Jul 29; Authors: Hwang ST, Kang SW, Lee SJ, Lee TH, Suh W, Shim SH, Lee DR, Taite LJ, Kim KS, Lee SH For clinical application of human embryonic stem cells (hESCs), it is critical to develop hESC culture techniques that completely exclude the use of animal feeder cells, mitotic inhibition, and enzyme treatments used in conventional hESC culture systems. Toward this goal, we attempted to maintain hESCs and induced pluripotent stem (iPS) cells on porous membranes (PMs) with proliferative human adipose-derived stromal cells (ASCs) seeded on the bottom surface of inverted PMs. This culture condition will ensure that the two cell types are separate from each other, yet retain the ability to interact through the pores of the membrane. We found that hESCs and iPS cells can be maintained stably and mechanically transferred without the need for enzyme treatment. In addition, the pluripotency of hESCs and iPS cells was stably maintained, as evidenced by immunostaining of Oct4, SSEA3/4 and TRA-1-60 as well as RT-PCR analyses of Nanog, Oct4 and Sox2 expression. Furthermore, hESCs cultured on PMs showed a normal karyotype and in vivo teratoma formation containing all three germ layers. PMID: 20674000 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Dose-dependent effect of adipose-derived adult stem cells on vertical bone regeneration in rabbit calvarium. Biomaterials. 2010 May;31(13):3527-35 Authors: Pieri F, Lucarelli E, Corinaldesi G, Aldini NN, Fini M, Parrilli A, Dozza B, Donati D, Marchetti C Previous in vivo studies have shown a limited potential for vertical bone regeneration using osteoconductive scaffolds alone. In the present study, we investigated whether the association of adipose-derived adult stem cells (ASCs) with anorganic bovine bone (ABB) scaffold improved bone formation and implant osseointegration in a vertical guided bone regeneration model. Two pre-formed titanium domes were placed on the calvaria of 12 rabbits. Four treatment modalities were evenly distributed among the 24 domes: ABB alone, and ABB containing 3 x 10(5), 3 x 10(6), or 3 x 10(7) cells/graft. After 1 month, the domes were removed and one titanium implant was placed into each augmented site. One month after the second operation, the animals were killed and biopsy specimens were examined by histomorphometric and micro-CT analyses. Results indicated that at all concentrations, the ASC-loaded groups showed significantly more new bone formation and higher mean values of bone-implant contact and bone density inside threads than the ABB group. Furthermore, ASCs demonstrated a dose-response relationship, with the highest dose chosen inducing more robust bone regeneration. This study suggests that the delivery of ASCs on ABB might effectively increase vertical bone regeneration and implant osseointegration, versus ABB alone. PMID: 20170950 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Overexpression of YAP1 induces immortalization of normal human keratinocytes by blocking clonal evolution. Histochem Cell Biol. 2010 Jul 31; Authors: D'Addario I, Abbruzzese C, Lo Iacono M, Teson M, Golisano O, Barone V YAP1 is a transcriptional co-activator able to bind several transcription factors. YAP1 was termed a candidate oncogene after it was shown to be in human chromosome 11q22 amplicon; besides the genomic amplification, several experiments indicated that it has oncogenic function. However, YAP1 was also reported to be a tumor suppressor as its gene locus is deleted in some breast cancers. To clarify the role of this protein in the physiology of rapidly renewal cells, we investigated YAP1 in human keratinocytes. Here, we show that YAP1 overexpression in primary human keratinocytes blocks clonal evolution and induces cell immortalization, but not malignant transformation. YAP1 overexpression led to an increase in cell proliferation, colony forming efficiency and holoclone percentage. Cells escaped from senescence, immortalized but still remained unable to grow in soft agar or express mesenchymal markers, suggesting that YAP1 overexpression is not sufficient to promote a complete epithelial-mesenchymal transition and tumorigenic transformation. Protein analysis showed an increase in epithelial proliferation markers and a decrease in epithelial differentiation markers. The expression of LEKTI, a late differentiation marker, dramatically dropped to undetectable levels. Taken together, these data suggest that YAP1-overexpressing keratinocytes are maintained in the proliferative compartment. PMID: 20677011 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Designing Bioactive Delivery Systems for Tissue Regeneration. Ann Biomed Eng. 2010 Jul 30; Authors: Davis HE, Leach JK The direct infusion of macromolecules into defect sites generally does not impart adequate physiological responses. Without the protection of delivery systems, inductive molecules may likely redistribute away from their desired locale and are vulnerable to degradation. In order to achieve efficacy, large doses supplied at interval time periods are necessary, often at great expense and ensuing detrimental side effects. The selection of a delivery system plays an important role in the rate of re-growth and functionality of regenerating tissue: not only do the release kinetics of inductive molecules and their consequent bioactivities need to be considered, but also how the delivery system interacts and integrates with its surrounding host environment. In the current review, we describe the means of release of macromolecules from hydrogels, polymeric microspheres, and porous scaffolds along with the selection and utilization of bioactive delivery systems in a variety of tissue-engineering strategies. PMID: 20676773 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Mathematical Modeling in Wound Healing, Bone Regeneration and Tissue Engineering. Acta Biotheor. 2010 Jul 31; Authors: Geris L, Gerisch A, Schugart RC The processes of wound healing and bone regeneration and problems in tissue engineering have been an active area for mathematical modeling in the last decade. Here we review a selection of recent models which aim at deriving strategies for improved healing. In wound healing, the models have particularly focused on the inflammatory response in order to improve the healing of chronic wound. For bone regeneration, the mathematical models have been applied to design optimal and new treatment strategies for normal and specific cases of impaired fracture healing. For the field of tissue engineering, we focus on mathematical models that analyze the interplay between cells and their biochemical cues within the scaffold to ensure optimal nutrient transport and maximal tissue production. Finally, we briefly comment on numerical issues arising from simulations of these mathematical models. PMID: 20676732 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | More than just bare scaffolds: towards multi-component and decorated fibrous biomaterials. Chem Soc Rev. 2010 Aug 2; Authors: Woolfson DN, Mahmoud ZN We are entering a new phase in biomaterials research in which rational design is being used to produce functionalised materials tailored to specific applications. As is evident from this Themed Issue, there are now a number of distinct types of designed, self-assembling, fibrous biomaterials. Many of these are ripe for development and application for example as scaffolds for 3D cell culture and tissue engineering, and in templating inorganic materials. Whilst a number of groups are making headway towards such applications, there is a general challenge to translate a wealth of excellent basic research into materials with a genuine future in real-life applications. Amongst other contemporary aspects of this evolving research area, a key issue is that of decorating or functionalising what are mostly bare scaffolds. There are a number of hurdles to overcome to achieve effective and controlled labelling of the scaffolds, for instance: maintaining biocompatibility, i.e., by minimising covalent chemistry, or using milder bioconjugation methods; attaining specified levels of decoration, and, in particular, high and stoichiometric labelling; introducing orthogonality, such that two or more functions can be appended to the same scaffold; and, in relevant cases, maintaining the possibility for recombinant peptide/protein production. In this critical review, we present an overview of the different approaches to tackling these challenges largely for self-assembled, peptide-based fibrous systems. We review the field as it stands by placing work within general routes to fibre functionalisation; give worked examples on our own specific system, the SAFs; and explore the potential for future developments in the area. Our feeling is that by tackling the challenges of designing multi-component and functional biomaterials, as a community we stand to learn a great deal about self-assembling biomolecular systems more broadly, as well as, hopefully, delivering new materials that will be truly useful in biotechnology and biomedical applications (107 references). PMID: 20676443 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | FGF-2 and VEGF functionalization of starPEG-heparin hydrogels to modulate biomolecular and physical cues of angiogenesis. Biomaterials. 2010 Jul 30; Authors: Zieris A, Prokoph S, Levental KR, Welzel PB, Grimmer M, Freudenberg U, Werner C Tissue engineering therapies require biomaterials capable of encouraging an angiogenic response. To dissect the influence of different pro-angiogenic stimuli a set of starPEG-heparin hydrogels with varied physicochemical properties was used as a highly efficient reservoir and tunable delivery system for basic fibroblast growth factor (FGF-2) and vascular endothelial growth factor (VEGF). The engineered gel materials could be precisely tailored by decoupling the biomolecular functionalization from the variation of the viscoelastic matrix characteristics. Culture experiments with human umbilical vein endothelial cells (HUVECs) revealed the interplay of growth factor presentation, adhesive characteristics and elasticity of the gel matrices in triggering differential cellular behavior which allowed identifying effective pro-angiogenic conditions. PMID: 20674970 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Nanostructured bacterial materials for innovative medicines. Trends Microbiol. 2010 Jul 29; Authors: RodrÃguez-Carmona E, Villaverde A The development of innovative medicines and personalized biomedical approaches require the identification and implementation of new biocompatible materials produced by methodologically simple and cheap fabrication methods. The biological fabrication of materials, mostly carried out by microorganisms, has historically provided organic compounds with wide-spectrum biomedical applications, including hyaluronic acid, poly(gamma-glutamic acid) and polyhydroxyalkanoates. Additionally, the implementation of new methodological platforms such as metabolic engineering and systems biology have facilitated the controlled production of natural nanoparticles produced by bacteria, including metallic deposits of Au, Ag, Cd, Zn or Fe, virus-like particles or other nanoscale protein-only entities. The unexpected potential of such self-organized and functional materials in nanomedical scenarios (especially in drug delivery, imaging and tissue engineering) prompts serious consideration of further exploitation of bacterial cell factories as convenient alternatives to chemical synthesis and as sources of novel bioproducts that could dramatically expand the existing catalog of biomedical materials. PMID: 20674365 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Patterning network structure to spatially control cellular remodeling and stem cell fate within 3-dimensional hydrogels. Biomaterials. 2010 Jul 29; Authors: Khetan S, Burdick JA The spatially directed 3-dimensional (3D) remodeling of synthetic materials may be useful to regionally control cell behavior. In this work, we developed a process to synthesize hyaluronic acid hydrogels using multiple modes of crosslinking applied sequentially; a primary addition reaction to introduce protease degradable peptide crosslinks, then a UV light-induced secondary radical reaction (enabling spatial control) to introduce non-degradable kinetic chains. These differential network structures either permitted (primary crosslinking only, "-UV") or inhibited (sequential crosslinking, "+UV") cellular remodeling. This behavior was validated by controlling the outgrowth from chick aortic arches or the spreading of encapsulated mesenchymal stem cells (MSCs), where only -UV regions permitted arch outgrowth and MSC spreading. Additionally, network structures dictated adipogenic/osteogenic MSC fate decisions, with spatial control, by controlling encapsulated MSC spreading. This manipulation of microenvironmental cues may be valuable for advanced tissue engineering applications requiring the spatial control of cells in 3D. PMID: 20674004 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Porous nanofibrous PLLA scaffolds for vascular tissue engineering. Biomaterials. 2010 Jul 29; Authors: Hu J, Sun X, Ma H, Xie C, Chen YE, Ma PX Tissue-engineered small-diameter vascular grafts are needed for patients requiring replacement of their injured coronary and below-the-knee vessels. Understanding the interactions between the scaffolds and implanted cells and therefore the phenotype control of smooth muscle cells (SMCs) is critical for constructing functional vascular grafts. In this study, the effect of nanofibrous (NF) poly-l-lactide (PLLA) scaffolds on phenotype control of human aortic smooth muscle cells (HASMCs) was investigated. A tubular NF PLLA scaffold for blood vessel regeneration was fabricated and cell seeding studies showed cell distribution throughout the scaffold. It was found that NF PLLA scaffolds preferentially supported contractile phenotype of HASMCs under the in vitro culture conditions, as evidenced by elevated gene expression level of SMCs contractile markers including smooth muscle myosin heavy chain, smoothelin and myocardin. In vivo subcutaneous implantation studies confirmed HASMCs differentiation in the implants. Taken together, the results showed promising application of the porous NF PLLA scaffolds for reconstruction of tissue-engineered vascular grafts. PMID: 20673997 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Finite element analysis of an accordion-like honeycomb scaffold for cardiac tissue engineering. J Biomech. 2010 Jul 29; Authors: Jean A, Engelmayr GC Optimizing the function of tissue engineered cardiac muscle is becoming more feasible with the development of microfabricated scaffolds amenable to mathematical modeling. In the current study, the elastic behavior of a recently developed poly(glycerol sebacate) (PGS) accordion-like honeycomb (ALH) scaffold [Engelmayr et al., 2008. Nature Materials 7 (12), 1003-1010] was analyzed. Specifically, 2D finite element (FE) models of the ALH unit cell (periodic boundary conditions) and tessellations (kinematic uniform boundary conditions) were utilized to determine a representative volume element (RVE) and to retrospectively predict the elastic effective stiffnesses. An RVE of 90 ALH unit cells ( approximately 3.18x4.03mm) was found, indicating that previous experimental uni-axial test samples were mechanically representative. For ALH scaffolds microfabricated from PGS cured 7.5h at 160 degrees C, FE predicted effective stiffnesses in the two orthogonal material directions (0.081+/-0.012 and 0.033+/-0.005MPa) matched published experimental data (0.083+/-0.004 and 0.031+/-0.002MPa) within 2.4% and 6.4%. Of potential use as a design criterion, model predicted global strain amplifications were lower in ALH (0.54 and 0.34) versus rectangular honeycomb (1.19 and 0.74) scaffolds, appearing to be inversely correlated with previously measured strains-to-failure. Important in matching the anisotropic mechanical properties of native cardiac muscle, FE predicted ALH scaffolds with 50mum wide PGS struts to be maximally anisotropic. The FE model will thus be useful in designing future variants of the ALH pore geometry that simultaneously provide proper cardiac anisotropy and reduced stiffness to enhance heart cell-mediated contractility. PMID: 20673666 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Establishment of Immortal Multipotent Rat Salivary Progenitor Cell Line Toward Salivary Gland Regeneration. Tissue Eng Part C Methods. 2010 Aug 1; Authors: Yaniv A, Neumann Y, David R, Stiubea-Cohen R, Orbach Y, Lang S, Rotter N, Ginzberg MD, Aframian DJ, Palmon A Adult salivary gland stem cells are promising candidates for cell therapy and tissue regeneration in cases of irreversible damage to salivary glands in head and neck cancer patients undergoing irradiation therapy. At present, the major restriction in handling such cells is their relatively limited life span during in vitro cultivation, resulting in an inadequate experimental platform to explore the salivary gland-originated stem cells as candidates for future clinical application in therapy. We established a spontaneous immortal integrin alpha6beta1-expressing cell line of adult salivary progenitor cells from rats (RSC) and investigated their ability to sustain cellular properties. This line was able to propagate for more than 400 doublings without loss of differentiation potential. RSC could differentiate in vitro to both acinar- and ductal-like structures and could be further manipulated upon culturing on a 3D scaffolds with different media supplements. Moreover, RSC expressed salivary specific mRNAs and proteins as well as the epithelial stem cell markers and upon differentiation process their expression were changed. These results suggest RSC as a good model for further studies exploring cellular senescence, differentiation and in vitro tissue engineering features as a crucial step toward re-engineering irradiation-impaired salivary glands. PMID: 20673137 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Osteogenic differentiation of human Wharton's jelly Stem Cells (hWJSCs) on nanofibrous substrates <i>in vitro</i> Tissue Eng Part A. 2010 Aug 1; Authors: Gauthaman K, Venugopal JR, Chui Yee F, Biswas A, Ramakrishna S, Bongso A Abstract Most tissue engineering studies use human bone marrow mesenchymal stem cells for differentiation into desirable lineages. We derived a novel stem cell from the human umbilical cord Wharton's jelly (hWJSC) that has numerous advantages over other stem cell types in that they can be harvested in abundance very efficiently and painlessly with no risk of patient morbidity, have prolonged stemness properties <i>in vitro</i>, are hypoimmunogenic and can be differentiated into many tissue types in two dimensional (2D) culture. We compared four different 3D nanofibrous scaffolds [polycaprolactone (PCL), PCL/Collagen (PCL/Coll), PCL/hydroxyapatite (PCL/HA) and PCL/Coll/HA] for the attachment, proliferation, differentiation and mineralization of hWJSCs into an osteogenic lineage. The collagen based scaffolds (PCL/Coll and PCL/Coll/HA) showed better cell attachment and proliferation compared to PCL and PCL/HA, with increases of 41.80% and 38.52% respectively. hWJSCs cultured on PCL/Coll/HA in osteogenic medium up to 21 days demonstrated increased alkaline phosphatase activity, greater expression of osteocalcin, mineralization and osteogenic related genes compared to controls. Given the advantages of hWJSCs over other stem cell types, we propose that hWJSCs may be efficiently differentiated into an osteogenic lineage on a 3D PCL/Coll/HA nanofibrous scaffold for the treatment of bone defects. Keywords: Human Wharton's Jelly stem cells, Nanofibres, Cell proliferation, Mineralization, Osteocalcin, Osteopontin. PMID: 20673136 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Hypoxia and amino acid supplementation synergistically promote the osteogenesis of human mesenchymal stem cells on silk protein scaffolds. Tissue Eng Part A. 2010 Aug 1; Authors: Sengupta S, Park S, Patel A, Carn J, Lee K, Kaplan DL Tailoring tissue engineering strategies to match patient and tissue specific bone regeneration needs offers to improve clinical outcomes. As a step toward this goal, osteogenic outcomes and metabolic parameters were assessed when varying inputs into the bone formation process. Silk protein scaffolds seeded with human mesenchymal stem cells in osteogenic differentiation media were used to study in-vitro osteogenesis under varied conditions of amino acid (lysine and proline) concentration and oxygen level. The cells were assessed to probe how the microenvironment impacted metabolic pathways and thus osteogenesis. The most favorable osteogenesis outcomes were found in the presence of low (5%) oxygen combined with high lysine and proline concentrations during in vitro cultivation. This same set of culture conditions also showed the highest glucose consumption, lactate synthesis and certain amino acid consumption rates. Based on these results and known pathways, a holistic metabolic model was derived which shows that lysine and proline supplements as well as low (5%) oxygen levels regulate collagen matrix synthesis and thereby rates of osteogenesis. This study establishes early steps toward a foundation for patient and tissue specific matches between metabolism, repair site and tissue engineering approaches towards optimized bone regeneration. PMID: 20673134 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Assembly and testing of stem cell-seeded layered collagen constructs for heart valve tissue engineering. Tissue Eng Part A. 2010 Jul 30; Authors: Tedder ME, Simionescu A, Chen J, Liao J, Simionescu DT Tissue engineering holds great promise for treatment of valvular diseases. Despite excellent progress in the field, current approaches do not fully take into account each patient's valve anatomical uniqueness, the presence of a middle spongiosa cushion that allows shearing of external fibrous layers (fibrosa and ventricularis) and the need for autologous valvular interstitial cells (VICs). In this study we propose a novel approach to heart valve tissue engineering based on bioreactor conditioning of mesenchymal stem cell-seeded, valve-shaped constructs assembled from layered collagenous scaffolds. Fibrous scaffolds were prepared by decellularization of porcine pericardium and spongiosa scaffolds by decellularization and elastase treatment of porcine pulmonary arteries. To create anatomically correct constructs, we created silicone molds from native porcine aortic valves, dried two identical fibrous scaffolds onto the molds and stabilized them with Penta-Galloyl-Glucose (PGG) a reversible collagen-binding polyphenol that reduces biodegradation. The layers were fused with a protein/aldehyde scaffold bio-adhesive and neutralized to reduce cytotoxicity. Spongiosa scaffolds, seeded with human bone marrow derived stem cells were inserted within the valve-shaped layered scaffolds and sutured inside the original aortic root. The final product was mounted in a heart valve bioreactor and cycled in cell culture conditions. Most cells were alive after 8 days, elongated significantly and stained positive for vimentin, similar to native human VICs, indicating feasibility of our approach. PMID: 20673028 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inhibition of aortic valvular interstitial cell degeneration by ECM modification - Implications for heart valve engineering. Tissue Eng Part A. 2010 Jul 30; Authors: Gwanmesia P, Ziegler H, Eurich R, Barth M, Kamiya H, Karck M, Lichtenberg A, Akhyari P The enhancement of valvular interstitial cell (VIC) calcification by TGF-beta1 (TGF-ss1) and the endothelial inducing effect of vascular endothelial growth factor (VEGF) have been demonstrated. Here we report the modulating properties of extracellular matrix modification on VIC calcification in the presence of TGF-ss1 and VEGF. Ovine aortic VIC cultured on collagen, fibronectin, laminin or uncoated surfaces were exposed to TGF-ss1, VEGF or left untreated. VEGF significantly inhibited the formation of calcific nodules independent of ECM protein coating (P<0.05). TGF-ss1 exposition resulted in the formation of calcific nodules on collagen, laminin and uncoated control surfaces. In contrast, fibronectin coating resulted in significantly reduced nodule formation despite TGF-ss1 administration. Furthermore we showed a marked increase of apoptotic and dead cells in calcific nodules. Overall, our data demonstrate that, an additive protective effect on VICs can be achieved by providing specific growth factors or a specific ECM environment. Here, VEGF administration inhibited calcification and apoptosis, particularly in combination with fibronectin coating. This combination appears to be a promising tool for modification of heart valve scaffolds for tissue engineering purposes and preclinical trials. PMID: 20673026 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Proliferation and differentiation of mesenchymal stem cell on collagen sponge reinforced with polypropylene/ polyethylene terephathalate blend fibers. Tissue Eng Part A. 2010 Jul 30; Authors: Mohajeri S, Hosseinkhani H, Golshan Ebrahimi N, Nikfarjam L, Soleimani M, Kajbafzadeh AM Abstract Despite the fact that tissue engineered scaffolds made from collagen sponge is suitable for cell infiltrating, easily supplying oxygen and nutrients to cells and removing the waste products; its mechanical properties are not satisfactory to be used as scaffold materials for tissue engineering applications. In order to improve mechanical properties of collagen, a novel porous scaffold for bone tissue engineering was prepared with collagen sponge reinforced by poly propylene/polyethylene terphthalate (PP/PET) fibers. Collagen solution (6.33 mg/ml) with PP/PET fibers (collagen/fiber ratio (w/w): 1.27, 0.63, 0.42, 0.25) was freeze-dried, followed by cross-linking of combined dehydrothermal and glutaraldehyde. A scanning electron microscopy (SEM)-based analysis of surface of the sponges demonstrated that the sponge with collagen/fiber less than 0.25 exhibited homogenous and interconnected pore structure with an average pore size of 200 mum. Incorporation of PP/PET fibers significantly enhanced the compressive strength of the collagen sponge. Proliferation and osteogenic differentiation of mesenchymal stem cell (MSC) in collagen sponges reinforced with PP/PET fibers incorporation were significantly enhanced compared with collagen sponge without PP/PET incorporation. We conclude that incorporation of PP/PET fibers not only improve the mechanical properties of collagen sponge, but also enable MSC to positively improve their proliferation and differentiation as well. PMID: 20673024 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Laser printing of stem cells for biofabrication of scaffold-free autologous grafts. Tissue Eng Part C Methods. 2010 Jul 30; Authors: Gruene M, Deiwick A, Koch L, Schlie S, Unger C, Hofmann N, Bernemann I, Glasmacher B, Chichkov BN Stem cells are of widespread interest in regenerative medicine due to their capability of self-renewal and differentiation, which is regulated by their three-dimensional microenvironment. In this study, a computer-aided biofabrication technique based on laser-induced forward transfer (LIFT) is used to generate grafts consisting of mesenchymal stem cells (MSCs). We demonstrate that: (i) laser printing does not cause any cell damage; (ii) laser printed MSC grafts can be differentiated towards bone and cartilage; (iii) LIFT allows printing of cell densities high enough for the promotion of chondrogenesis; (iv) with LIFT three-dimensional scaffold-free autologous tissue grafts can be fabricated keeping their predefined structure, and (v) pre-differentiated MSCs survived the complete printing procedure and kept their functionality. We believe that our results will find important applications in stem cell biology and tissue engineering. PMID: 20673023 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Chondrogenesis and mineralization during in vitro culture of human mesenchymal stem cells on 3D-woven scaffolds. Tissue Eng Part A. 2010 Jul 30; Authors: Abrahamsson CK, Yang F, Park H, Brunger JM, Valonen PK, Langer RS, Welter JF, Caplan AI, Guilak F, Freed LE Human mesenchymal stem cells (hMSCs) and three dimensionally (3D)-woven poly(e-caprolactone) (PCL) scaffolds are promising tools for skeletal tissue engineering. We hypothesized that in vitro culture duration and medium additives can individually and interactively influence the structure, composition, mechanical and molecular properties of engineered tissues based on hMSCs and 3D PCL. Bone marrow hMSCs were suspended in collagen gel, seeded on scaffolds, and cultured for 1, 21, or 45 days in under chondrogenic and/or osteogenic conditions. Structure, composition, biomechanics and gene expression were analyzed. In chondrogenic medium, cartilaginous tissue formed by day 21, and hypertrophic mineralization was observed in the newly formed extracellular matrix at the interface with underlying scaffold by day 45. Glycosaminoglycan, hydroxyproline, and calcium contents, and alkaline phosphatase activity depended on culture duration and medium additives, with significant interactive effects (all p<0.0001). The 45-day constructs exhibited mechanical properties on the order of magnitude of native articular cartilage (aggregate, Young's and shear moduli of 0.15 MPa, 0.12 MPa and 0.033 MPa, respectively). Gene expression was characteristic of chondrogenesis and endochondral bone formation, with sequential regulation of Sox-9, collagen type II, aggrecan, Cbfalpha1/Runx2, bone sialoprotein, bone morphogenic protein-2, and osteocalcin. In contrast, osteogenic medium produced limited osteogenesis. Long-term culture of hMSC on 3D scaffolds resulted in chondrogenesis and regional mineralization at the interface between soft, newly formed engineered cartilage and stiffer underlying scaffold. These findings merit consideration when developing grafts for osteochondral defect repair. PMID: 20673022 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Enhanced biochemical and biomechanical properties of scaffolds generated by flock technology for cartilage tissue engineering. Tissue Eng Part A. 2010 Jul 30; Authors: Steck E, Bertram H, Walther A, Brohm K, Mrozik B, Rathmann M, Merle C, Gelinsky M, Richter W Natural cartilage shows column orientation of cells and anisotropic direction of collagen fibers. However, matrices presently used in matrix assisted autologous chondrocyte implantation do not show any fiber orientation. Our aim was to develop anisotropic scaffolds with parallel fiber orientation that were capable to support a cellular cartilaginous phenotype in vitro. Scaffolds were created by flock technology and consisted of a membrane of mineralized collagen-type-I as substrate, gelatine as adhesive, and parallel oriented polyamide flock fibers vertically to the substrate. Confocal laser-scan microscopy demonstrated that mesenchymal stem cells (MSC) adhered and proliferated well in the scaffolds and cell vitality remained high over time. Articular chondrocytes seeded in a collagen-type-I gel into flock scaffolds deposited increasing amounts of proteoglycans and collagen-type-II over time. MSC-seeded flock scaffold constructs under chondrogenic conditions deposited significantly more proteoglycans and collagen-type-II compared to MSC collagen-type-I-gel-constructs only. Biomechanical testing revealed higher initial hardness of flock scaffolds compared to a clinically applied collagen-type-I/III scaffold combined with superior relaxation and an increasing hardness in MSC loaded flock biocomposites during chondrogenesis. In conclusion, flock technology allows fabrication of scaffolds with anisotropic fiber orientation which mediate superior biomechanical and biochemical composition of tissue engineering constructs for cartilage repair. PMID: 20673020 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Functional Evaluation of Artificial Skeletal Muscle Tissue Constructs Fabricated by a Magnetic Force-Based Tissue Engineering Technique. Tissue Eng Part A. 2010 Jul 30; Authors: Yamamoto Y, Ito A, Fujita H, Nagamori E, Kawabe Y, Kamihira M Skeletal muscle tissue engineering is currently applied in a variety of research fields, including regenerative medicine, drug screening and bio-actuator development, all of which require the fabrication of bio-mimic and functional skeletal muscle tissues. In the present study, magnetite cationic liposomes were used to magnetically label C2C12 myoblast cells for the construction of three-dimensional artificial skeletal muscle tissues by an applied magnetic force. Skeletal muscle functions, such as biochemical and contractile properties, were evaluated for the artificial tissue constructs. Histological studies revealed that elongated and multinucleated myotubes were observed within the tissue. Expression of muscle specific markers, such as myogenin, myosin heavy chain and tropomyosin, were detected in the tissue constructs by western blot analysis. Furthermore, creatine kinase activity increased during differentiation. In response to electric pulses, the artificial tissue constructs contracted to generate a physical force [the maximum twitch force, 33.2 microN (1.06 mN/mm<sup>2</sup>)]. Rheobase and chronaxie of the tissue were determined as 4.45 V and 0.72 ms, respectively. These results indicate that the artificial skeletal muscle tissue constructs fabricated in this study were physiologically functional and the data obtained for the evaluation of their functional properties may provide useful information for future skeletal muscle tissue engineering studies. PMID: 20672996 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Controlled delivery of TGF-beta1 by self-assembling peptide hydrogels induces chondrogenesis of bone marrow stromal cells and modulates Smad 2/3 signaling. Tissue Eng Part A. 2010 Jul 30; Authors: Kopesky PW, Vanderploeg EJ, Kisiday J, Frisbie DD, Sandy JS, Grodzinsky A Self-assembling peptide hydrogels were modified to deliver TGF-beta1 to encapsulated bone-marrow derived stromal cells (BMSCs) for cartilage tissue engineering applications using two different approaches: biotin-streptavidin tethering or adsorption to the peptide scaffold. Initial studies to determine the duration of TGF-beta1 medium supplementation necessary to stimulate chondrogenesis showed that 4 days of transient soluble TGF-beta1 to newborn bovine BMSCs resulted in 10-fold higher proteoglycan accumulation than TGF-beta1-free culture after 3 weeks. Subsequently BMSC-seeded peptide hydrogels with either tethered or adsorbed TGF-beta1 were cultured in TGF-beta1-free medium, and chondrogenesis was compared to that for BMSCs encapsulated in unmodified peptide hydrogels, both with and without soluble TGF-beta1 medium supplementation. Adsorbed TGF-beta1 peptide hydrogels stimulated chondrogenesis of BMSCs as demonstrated by cell proliferation and cartilage-like ECM accumulation, while tethered TGF-beta1 did not stimulate chondrogenesis. In parallel experiments, TGF-beta1 adsorbed to agarose hydrogels stimulated comparable chondrogenesis. Full-length aggrecan was produced by BMSCs in response to adsorbed TGF-beta1 in both peptide and agarose hydrogels, while medium-delivered TGF-beta1 stimulated catabolic aggrecan cleavage product formation in agarose but not peptide scaffolds. Smad2/3 was transiently phosphorylated in response to adsorbed but not tethered TGF-beta1, while medium-delivered TGF-beta1 produced sustained signaling, suggesting that dose and signal duration are potentially important for minimizing aggrecan cleavage product formation. Robustness of this technology for use in multiple species and ages was demonstrated by effective chondrogenic stimulation of adult equine BMSCs, an important translational model used prior to the initiation of human clinical studies. PMID: 20672992 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [The genetic basis for skeletal disease. Stem cell therapy for genetic bone disorders.] Clin Calcium. 2010 Aug;20(8):1228-35 Authors: Tadokoro M, Machida H, Ohgushi H Mesenchymal stem cells (MSCs) can show osteogenic differentiation capability when implanted in vivo , as well as cultured in vitro ; therefore we attempted to use allogeneic MSCs for a patient with hypophosphatasia, which is caused by mutations in tissue non-specific alkaline phosphatase (TNSALP) gene. Donor MSCs were obtained by culture expansion of fresh marrow from the patient's father. Some of the MSCs were further cultured under osteogenic conditions on a culture dish or porous hydroxyapatite ceramics, resulting in cultured osteoblasts and osteogenic constructs, respectively. After traditional bone marrow transplantation, The donor MSCs and osteoblasts were injected into the patient and the constructs were implanted subcutaneously or intraosseous lesions. The patient's respiratory condition improved and donor cells were detected in newly formed bone tissue. These findings showed the importance of allogeneic MSC transplantation for the hypophosphatasia patient. PMID: 20675934 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Cholesterol myristate suppresses the apoptosis of mesenchymal stem cells via upregulation of inhibitor of differentiation. Steroids. 2010 Jul 29; Authors: Chen DF, Zhang HL, Du SH, Li H, Zhou JH, Li YW, Zeng HP, Hua ZC To identify small molecules that suppress the apoptosis of mesenchymal stem cells (MSCs) is promising for stem cell therapy. We recently showed that BMP4 signaling involves effect of cholesterol myristate on proliferation of MSCs. The present study evaluated the effects of cholesterol myristate on the apoptosis of MSCs and the inhibitor of differentiation (Id1), target gene of BMP4 signaling. MSCs transfected by Id1 promoter reporter construct, cholesterol myristate increases the activity of Id1 promoter. However, structurally-related steroids such as cholesterol, beta-sitosterol and cholesten-3-one, lack of the myristate, did not affect the activity of Id1 promoter, suggesting that myristate is essential for this effects. This effect depends on BMP signaling. Apoptosis analysis indicated that cholesterol myristate inhibited the apoptosis of MSCs induced by serum-free. Cholesterol myristate increases the expression of Id1 and its target gene bcl-x/l in MSCs treated with serum-free. Moreover, noggin, BMP antagonist, reduced the anti-apoptotic effects of cholesterol myristate. Thus, this study is to provide evidence that cholesterol myristate suppresses the apoptosis of MSCs via up-regulation of Id1. These findings can be applied for improving MSCs survival in stem cell transplantation, bone marrow transplantation, treatment of bone diseases such as osteoporosis and chemotherapy. PMID: 20674581 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Adipose-derived stem and stromal cells for cell-based therapy: Current status of preclinical studies and clinical trials. Curr Opin Mol Ther. 2010 Aug;12(4):442-9 Authors: Mizuno H The potential use of stem cell-based therapies for the repair and regeneration of various tissues and organs offers a paradigm shift that may provide alternative therapeutic solutions for several diseases. The clinical use of either embryonic stem cells or induced pluripotent stem cells remains limited because of cell regulations, ethical considerations and the requirement for genetic manipulation, although these cells are theoretically highly beneficial. Adipose-derived stem cells (ASCs) appear to be an ideal population of stem cells for practical regenerative medicine, given that they are plentiful, of autologous tissue origin and thus non-immunogenic, and are more easily available because of minimal ethical considerations. Although ASCs originate from mesodermal lineages, recent preclinical studies have demonstrated that the use of ASCs in regenerative medicine is not limited to mesodermal tissue, but can also extend to both exodermal and endodermal tissues and organs. This review summarizes and discusses current preclinical and clinical data on the use of ASCs in regenerative medicine and discusses the future applications of such cell-based therapies. PMID: 20677095 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | From hemorheology to microcirculation and regenerative medicine: FÃ¥hraeus Lecture 2009. Clin Hemorheol Microcirc. 2010;45(2-4):79-99 Authors: Jung F PMID: 20675888 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Post Translational Modification by SUMO. Toxicology. 2010 Jul 29; Authors: Hannoun Z, Greenhough S, Jaffray E, Hay RT, Hay DC Post translational modifications (PTMs) are chemical alterations to a protein following translation, regulating stability and function. Reversible phosphorylation is an example of an important and well studied PTM involved in a number of cellular processes. SUMOylation is another PTM known to modify a large number of proteins and plays a role in various cellular processes including; cell cycle regulation, gene transcription, differentiation and cellular localisation. Therefore, understanding the role of SUMOylation in cell biology may allow the development of more efficient models, important in streamlining the drug discovery process. This review will focus on protein SUMOylation and its role in stem cell and somatic cell biology. PMID: 20674646 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pluripotent Stem Cell Derived Hepatocyte Like Cells and their Potential in Toxicity Screening. Toxicology. 2010 Jul 29; Authors: Greenhough S, Medine CN, Hay DC Despite considerable progress in modelling human liver toxicity, the requirement still exists for efficient, predictive and cost effective in vitro models to reduce attrition during drug development. Thousands of compounds fail in this process, with hepatotoxicity being one of the significant causes of failure. The cost of clinical studies is substantial, therefore it is essential that toxicological screening is performed early on in the drug development process. Human hepatocytes represent the gold standard model for evaluating drug toxicity, but are a limited resource. Current alternative models are based on immortalised cell lines and animal tissue, but these are limited by poor function, exhibit species variability and show instability in culture. Pluripotent stem cells are an attractive alternative as they are capable of self renewal and differentiation to all three germ layers, and thereby represent a potentially inexhaustible source of somatic cells. The differentiation of human embryonic stem cells and induced pluripotent stem cells to functional hepatocyte like cells has recently been reported. Further development of this technology could lead to the scalable production of hepatocyte like cells for liver toxicity screening and clinical therapies. Additionally, induced pluripotent stem cell derived hepatocyte like cells may permit in vitro modelling of gene polymorphisms and genetic diseases. PMID: 20674645 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Sequential delivery of vascular endothelial growth factor and sphingosine 1-phosphate for angiogenesis. Biomaterials. 2010 Jul 29; Authors: Tengood JE, Kovach KM, Vescovi PE, Russell AJ, Little SR Angiogenesis is an organized series of events, beginning with vessel destabilization, followed by endothelial cell re-organization, and ending with vessel maturation. Vascular endothelial growth factor (VEGF) aids in vascular permeability and endothelial cell recruitment while sphingosine 1-phosphate (S1P) stimulates vascular stability. Accordingly, VEGF may inhibit vessel stabilization while S1P may inhibit endothelial cell recruitment. For this reason, we created a new externally-regulated delivery model that not only permits sustained release of bioactive factors, but also temporal separation of the delivery of growth factors. Using this model, sequential delivery of factors was first confirmed in vitro with associated endothelial cells responding in a dose dependent manner. Furthermore, using a modified murine Matrigel plug model, it is apparent that delivery strategies where VEGF presentation is temporally separated from S1P presentation not only led to greater recruitment of endothelial cells, but also higher maturation index of associated vessels. PMID: 20674008 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Finite element analysis of an accordion-like honeycomb scaffold for cardiac tissue engineering. J Biomech. 2010 Jul 29; Authors: Jean A, Engelmayr GC Optimizing the function of tissue engineered cardiac muscle is becoming more feasible with the development of microfabricated scaffolds amenable to mathematical modeling. In the current study, the elastic behavior of a recently developed poly(glycerol sebacate) (PGS) accordion-like honeycomb (ALH) scaffold [Engelmayr et al., 2008. Nature Materials 7 (12), 1003-1010] was analyzed. Specifically, 2D finite element (FE) models of the ALH unit cell (periodic boundary conditions) and tessellations (kinematic uniform boundary conditions) were utilized to determine a representative volume element (RVE) and to retrospectively predict the elastic effective stiffnesses. An RVE of 90 ALH unit cells ( approximately 3.18x4.03mm) was found, indicating that previous experimental uni-axial test samples were mechanically representative. For ALH scaffolds microfabricated from PGS cured 7.5h at 160 degrees C, FE predicted effective stiffnesses in the two orthogonal material directions (0.081+/-0.012 and 0.033+/-0.005MPa) matched published experimental data (0.083+/-0.004 and 0.031+/-0.002MPa) within 2.4% and 6.4%. Of potential use as a design criterion, model predicted global strain amplifications were lower in ALH (0.54 and 0.34) versus rectangular honeycomb (1.19 and 0.74) scaffolds, appearing to be inversely correlated with previously measured strains-to-failure. Important in matching the anisotropic mechanical properties of native cardiac muscle, FE predicted ALH scaffolds with 50mum wide PGS struts to be maximally anisotropic. The FE model will thus be useful in designing future variants of the ALH pore geometry that simultaneously provide proper cardiac anisotropy and reduced stiffness to enhance heart cell-mediated contractility. PMID: 20673666 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Long-Term Phenotypic Study after Allogeneic Cultivated Corneal Limbal Epithelial Transplantation for Severe Ocular Surface Diseases. Ophthalmology. 2010 Jul 27; Authors: Nakamura T, Sotozono C, Bentley AJ, Mano S, Inatomi T, Koizumi N, Fullwood NJ, Kinoshita S PURPOSE: To determine the long-term epithelial lineage of origin of surgically removed grafts after allogeneic cultivated corneal limbal epithelial transplantation (CLET). DESIGN: Interventional case reports. PARTICIPANTS: We studied 2 eyes from 2 patients with total corneal stem cell destruction; 1 eye was from a patient with Stevens-Johnson syndrome and 1 eye had sustained chemical injury. METHODS: Allogeneic cultivated corneal limbal epithelial sheets on human amniotic membrane (AM) were transplanted onto the ocular surface. Regrafting (1 eye, 42 months later) or penetrating keratoplasty (1 eye, 75 months later) were performed after the initial transplantation procedure for further visual rehabilitation. MAIN OUTCOME MEASURES: The excised grafts were subjected to clinical evaluation and to light- and transmission electron microscopy (TEM) examination and to immunohistochemical analysis. RESULTS: In clinically conjunctival grafts, TEM and immunohistochemical analysis disclosed only small areas where the original cultivated corneal epithelial cells persisted. Neighboring conjunctival epithelial cells had apparently invaded a large portion of the corneal surface (keratin 3/12(-), Muc5ac(+)). In clinically corneal grafts, transplanted allogeneic cultivated corneal epithelial cells clearly survived for a long period of time (keratin 3/12(+), Muc5ac(-)); there was no infiltration by inflammatory cells, nor was there dissolution of the AM substrate. CONCLUSIONS: We theorize that the process of graft opacification after allogeneic CLET is responsible for the loss of transplanted cultivated corneal epithelial cells and that this is followed by conjunctival cell invasion onto the corneal surface. The results of this study confirmed that in the clinically evaluated corneal graft, transplanted cultivated corneal epithelial cells indeed survived for a long period of time on the corneal surface and maintained ocular surface integrity, even though the transplanted cells were allogeneic. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any of the materials discussed in this article. PMID: 20673588 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | ISOLATION AND CHARACTERIZATION OF MESENCHYMAL STEM CELLS FROM HUMAN AMNIOTIC MEMBRANE. Tissue Eng Part C Methods. 2010 Aug 1; Authors: Diaz-Pardo S, Muiños-Lopez E, Hermida T, Rendal E, Fuentes-Boquete I, de Toro FJ, Blanco FJ Introduction: The human amniotic membrane (HAM), a highly abundant and readily available tissue that may be useful for regenerative medicine and cell therapy. Aim: To compare two previously published protocols for the isolation of human amnion mesenchymal stromal cells (hAMSCs), including their phenotypic characterization and in vitro potential for differentiation toward osteogenic, adipogenic and chondrogenic mesodermal lineages. Materials and Methods: Human placentas were obtained from selected caesarean-sectioned births. Two different protocols (Alviano et al. [1] and Soncini et al. [2]) for the isolation of hAMSCs were performed. After monolayer expansion of adherent cells from both protocols, the cells were characterized by flow cytometry and for multipotentiality, as assessed by their capability to differentiate toward adipocyte-, osteoblast- and chondocyte-like cells. Results: Both protocols yielded hAMSCs that showed plastic adherence, fibroblast-like growth and well-defined human MSC markers. The cell yield and mesodermal differentiation capability of hAMSCs were higher in cells isolated using the Soncini protocol. Conclusions: Our data demonstrated the successful isolation of hAMSCs from full-term placentas using two published protocols. Differences between the two protocols in cell yield and in vitro differentiation potential were shown. PMID: 20673138 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Laser printing of stem cells for biofabrication of scaffold-free autologous grafts. Tissue Eng Part C Methods. 2010 Jul 30; Authors: Gruene M, Deiwick A, Koch L, Schlie S, Unger C, Hofmann N, Bernemann I, Glasmacher B, Chichkov BN Stem cells are of widespread interest in regenerative medicine due to their capability of self-renewal and differentiation, which is regulated by their three-dimensional microenvironment. In this study, a computer-aided biofabrication technique based on laser-induced forward transfer (LIFT) is used to generate grafts consisting of mesenchymal stem cells (MSCs). We demonstrate that: (i) laser printing does not cause any cell damage; (ii) laser printed MSC grafts can be differentiated towards bone and cartilage; (iii) LIFT allows printing of cell densities high enough for the promotion of chondrogenesis; (iv) with LIFT three-dimensional scaffold-free autologous tissue grafts can be fabricated keeping their predefined structure, and (v) pre-differentiated MSCs survived the complete printing procedure and kept their functionality. We believe that our results will find important applications in stem cell biology and tissue engineering. PMID: 20673023 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Functional Evaluation of Artificial Skeletal Muscle Tissue Constructs Fabricated by a Magnetic Force-Based Tissue Engineering Technique. Tissue Eng Part A. 2010 Jul 30; Authors: Yamamoto Y, Ito A, Fujita H, Nagamori E, Kawabe Y, Kamihira M Skeletal muscle tissue engineering is currently applied in a variety of research fields, including regenerative medicine, drug screening and bio-actuator development, all of which require the fabrication of bio-mimic and functional skeletal muscle tissues. In the present study, magnetite cationic liposomes were used to magnetically label C2C12 myoblast cells for the construction of three-dimensional artificial skeletal muscle tissues by an applied magnetic force. Skeletal muscle functions, such as biochemical and contractile properties, were evaluated for the artificial tissue constructs. Histological studies revealed that elongated and multinucleated myotubes were observed within the tissue. Expression of muscle specific markers, such as myogenin, myosin heavy chain and tropomyosin, were detected in the tissue constructs by western blot analysis. Furthermore, creatine kinase activity increased during differentiation. In response to electric pulses, the artificial tissue constructs contracted to generate a physical force [the maximum twitch force, 33.2 microN (1.06 mN/mm<sup>2</sup>)]. Rheobase and chronaxie of the tissue were determined as 4.45 V and 0.72 ms, respectively. These results indicate that the artificial skeletal muscle tissue constructs fabricated in this study were physiologically functional and the data obtained for the evaluation of their functional properties may provide useful information for future skeletal muscle tissue engineering studies. PMID: 20672996 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Electrospun Chitosan-Alginate Nanofibers with In Situ Polyelectrolyte Complexation for Use as Tissue Engineering Scaffolds. Tissue Eng Part A. 2010 Jul 30; Authors: Jeong SI, Krebs MD, Bonino CA, Samorezov JE, Khan SA, Alsberg E Electrospun natural biopolymers are of great interest in the field of regenerative medicine due to their unique structure, biocompatibility, and potential to support controlled release of bioactive agents and/or the growth of cells near a site of interest. The ability to electrospin chitosan and alginate to form polyionic complexed nanofibrous scaffolds was investigated. These nanofibers crosslink in situ during the electrospinning process, and thus do not require an additional chemical crosslinking step. Although poly(ethylene oxide) (PEO) is required for the electrospinning, it can be subsequently removed from the nanofibers simply by incubating in water for a few days, as confirmed by ATR FT-IR. Solutions that allowed uniform nanofiber formation were found to have viscosities in the range of 0.15-0.7 Pa*s and conductivities below 4 mS/cm for chitosan-PEO and below 2.2 mS/cm for alginate-PEO. The resultant nanofibers both before and after PEO-extraction were found to be uniform and on the order of 100 nm as determined by scanning electron microscopy. The dynamic rheological properties of the polymer mixtures during gelation indicated that the hydrogel mixtures with low storage moduli provided uniform nanofiber formation without beaded structures. Increased amounts of chitosan in the PEO-extracted chitosan-alginate nanofibers resulted in a lower swelling ratio. Additionally, these nanofibrous scaffolds exhibit increased cell adhesion and proliferation compared to those made of alginate alone, due to the presence of the chitosan which promotes the adsorption of serum proteins. Thus, these nanofibrous scaffolds formed purely via ionic complexation without toxic crosslinking agents have great potential for guiding cell behavior in tissue regeneration applications. PMID: 20672984 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | [Erythropoietin: pleiotropic actions] Recenti Prog Med. 2010 Jun;101(6):253-67 Authors: Buemi M, Donato V, Bolignano D The erythropoietin is produced by the kidney and other organs. EPO does not only affect erythroid cells, but also other blood cell lines, such as myeloid cells, lymphocytes and megakaryocytes. This hormone can also enhance phagocytes function of the polymorph nuclear cells and reduces the activation of macrophages, thus modulating the inflammatory process. Hematopoietic and endothelial cells probably have the same cellular origin, and the discovery of erythropoietin receptors also on mesangial and myocardial cells and smooth muscle fibro-cells has prompted the study of the pleiotropic actions of this hormone. Through its receptors, spread out over the body, it carries out many actions which range from the erythrogenesis after hypoxic stimuli to the tissue protection of the heart and the brain after ischemia. Erythropoietin also acts in the endothelial proliferation of new vessels involving the tumor genesis, but it opens new frontiers to the employment of rHuEPO in the Regenerative Medicine. PMID: 20672574 [PubMed - in process] | | | | | | | | | | |  |
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