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| Regulation of embryonic stem cell self-renewal and differentiation by TGF-beta family signaling.
July 3, 2010 at 1:16 PM
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| | Regulation of embryonic stem cell self-renewal and differentiation by TGF-beta family signaling. Sci China Life Sci. 2010 Apr;53(4):497-503 Authors: Fei T, Chen YG Embryonic stem (ES) cells are characterized by their ability to indefinitely self-renew and potential to differentiate into all the cell lineages of the body. ES cells are considered to have potential applications in regenerative medicine. In particular, the emergence of an ES cell analogue - induced pluripotent stem (iPS) cells via somatic cell reprogramming by co-expressing a limited number of critical stemness-related transcriptional factors has solved the problem of obtaining patient-specific pluripotent cells, encouraging researchers to develop more specific and functional cell lineages from ES or iPS cells for broad therapeutic applications. ES cell fate choice is delicately controlled by a core transcriptional network, epigenetic modification profiles and complex signaling cascades both intrinsically and extrinsically. Of these signals, transforming growth factor beta (TGF-beta) family members, including TGF-beta, bone morphogenetic protein (BMP), Activin and Nodal, have been reported to influence cell self-renewal and a broad spectrum of lineage differentiation in ES cells, in accordance with the key roles of TGF-beta family signaling in early embryo development. In this review, the roles of TGF-beta family signals in coordinating ES cell fate determination are summarized. PMID: 20596917 [PubMed - as supplied by publisher] | | |
| Medaka fish stem cells and their applications.
July 3, 2010 at 1:16 PM
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| | Medaka fish stem cells and their applications. Sci China Life Sci. 2010 Apr;53(4):426-434 Authors: Yi M, Hong N, Li Z, Yan Y, Wang D, Zhao H, Hong Y Stem cells are present in developing embryos and adult tissues of multicellular organisms. Owing to their unique features, stem cells provide excellent opportunities for experimental analyses of basic developmental processes such as pluripotency control and cell fate decision and for regenerative medicine by stem cell-based therapy. Stem cell cultures have been best studied in 3 vertebrate organisms. These are the mouse, human and a small laboratory fish called medaka. Specifically, medaka has given rise to the first embryonic stem (ES) cells besides the mouse, the first adult testis-derived male stem cells spermatogonia capable of test-tube sperm production, and most recently, even haploid ES cells capable of producing Holly, a semi-cloned fertile female medaka from a mosaic oocyte created by microinjecting a haploid ES cell nucleus directly into a normal oocyte. These breakthroughs make medaka a favoring vertebrate model for stem cell research, the topic of this review. PMID: 20596908 [PubMed - as supplied by publisher] | | |
| Effects of chitosan/collagen substrates on the behavior of rat neural stem cells.
July 3, 2010 at 1:16 PM
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| | Effects of chitosan/collagen substrates on the behavior of rat neural stem cells. Sci China Life Sci. 2010 Feb;53(2):215-222 Authors: Yang Z, Mo L, Duan H, Li X Spinal cord and brain injuries usually lead to cavity formation. The transplantation by combining stem cells and tissue engineering scaffolds has the potential to fill the cavities and replace the lost neural cells. Both chitosan and collagen have their unique characteristics. In this study, the effects of chitosan and collagen on the behavior of rat neural stem cells (at the neurosphere level) were tested in vitro in terms of cytotoxicity and supporting ability for stem cell survival, proliferation and differentiation. Under the serum-free condition, both chitosan membranes and collagen gels had low cytotoxicity to neurospheres. That is, cells migrated from neurospheres, and processes extended out from these neurospheres and the differentiated cells. Compared with the above two materials, chitosan-collagen membranes were more suitable for the co-culture with rat neural stem cells, because, except for low cytotoxicity and supporting ability for the cell survival, in this group, a large number of cells were observed to migrate out from neurospheres, and the differentiating percentage from neurospheres into neurons was significantly increased. Further modification of chitosan-collagen membranes may shed light on in vivo nerve regeneration by transplanting neural stem cells. PMID: 20596830 [PubMed - as supplied by publisher] | | |
| Growth and Differentiation Properties of Mesenchymal Stromal Cell Populations Derived from Whole Human Umbilical Cord.
July 3, 2010 at 1:16 PM
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| | Growth and Differentiation Properties of Mesenchymal Stromal Cell Populations Derived from Whole Human Umbilical Cord. Stem Cell Rev. 2010 Jul 2; Authors: Majore I, Moretti P, Stahl F, Hass R, Kasper C Up to 2.8 x 10(7) fibroblast-like cells displaying an abundant presence of mesenchymal stem cell (MSC) markers CD73, CD90, CD105 and a low level of HLA-I expression can be isolated from one whole human umbilical cord (UC) using a simple and highly reproducible explant culture approach. Cells derived from whole UC, similar to cells collected from separate compartments of UC, display a distinct chondrogenic and adipogenic potential. Therefore they are potential candidates for cartilage and adipose tissue engineering. Cell differentiation along the osteogenic pathway is, however, less efficient, even after the addition of 1.25-dihydroxyvitamin D3, a potent osteoinductive substance. Isolated cells are highly proliferative, tolerate cryopreservation with an average survival rate of about 75% and after thawing can be propagated further, at least over 20 population doublings before their proliferative activity begins to decline. More importantly, they synthesize numerous trophic factors including neurotrophins and factors which facilitate angiogenesis and hematopoiesis. In conclusion, cells isolated from whole UC satisfies all requirements essential for the generation of stem cell banks containing permanently available cell material for applications in the field of regenerative medicine. Nevertheless, further studies are needed to improve and adjust the methods which are already employed for adult MSC expansion and differentiation to specific properties and requirements of the primitive stem cells collected from UC. So, our data verify that the choice of individual parameters for cell propagation, such as duration of cell expansion and cell seeding density, has a substantial impact on the quality of UC-derived cell populations. PMID: 20596801 [PubMed - as supplied by publisher] | | |
| Heparinized hydroxyapatite/collagen three-dimensional scaffolds for tissue engineering.
July 3, 2010 at 1:16 PM
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| | Heparinized hydroxyapatite/collagen three-dimensional scaffolds for tissue engineering. J Mater Sci Mater Med. 2010 Jul 2; Authors: Teixeira S, Yang L, Dijkstra PJ, Ferraz MP, Monteiro FJ Currently, in bone tissue engineering research, the development of appropriate biomaterials for the regeneration of bony tissues is a major concern. Bone tissue is composed of a structural protein, collagen type I, on which calcium phosphate crystals are enclosed. For tissue engineering, one of the most applied strategies consists on the development and application of three dimensional porous scaffolds with similar composition to the bone. In this way, they can provide a physical support for cell attachment, proliferation, nutrient transport and new bone tissue infiltration. Hydroxyapatite is a calcium phosphate with a similar composition of bone and widely applied in several medical/dentistry fields. Therefore, in this study, hydroxyapatite three dimensional porous scaffolds were produced using the polymer replication method. Next, the porous scaffolds were homogeneously coated with a film of collagen type I by applying vacuum force. Yet, due to collagen degradability properties, it was necessary to perform an adequate crosslinking method. As a result, N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was employed as an efficient and non-toxic crosslinking method in this research. The composites were characterized by means of SEM, DSC and TNBS. Furthermore, heparin was incorporated in order to accomplish sustained delivery of a growth factor of interest namely, bone morphogenetic proteins (BMP-2). BMP-2 binding and release of non-heparinized and heparinized scaffolds was evaluated at specific time points. The incorporation of heparin leads to a reduced initial burst phase when compared to the non heparinized materials. The results show a beneficial effect with the incorporation of heparin and its potential as a localized drug delivery system for the sustained release of growth factors. PMID: 20596760 [PubMed - as supplied by publisher] | | |
| Design of novel three-phase PCL/TZ-HA biomaterials for use in bone regeneration applications.
July 3, 2010 at 1:16 PM
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| | Design of novel three-phase PCL/TZ-HA biomaterials for use in bone regeneration applications. J Mater Sci Mater Med. 2010 Jul 2; Authors: Salerno A, Oliviero M, Di Maio E, Netti PA, Rofani C, Colosimo A, Guida V, Dallapiccola B, Palma P, Procaccini E, Berardi AC, Velardi F, Teti A, Iannace S The design of bioactive scaffold materials able to guide cellular processes involved in new-tissue genesis is key determinant in bone tissue engineering. The aim of this study was the design and characterization of novel multi-phase biomaterials to be processed for the fabrication of 3D porous scaffolds able to provide a temporary biocompatible substrate for mesenchymal stem cells (MSCs) adhesion, proliferation and osteogenic differentiation. The biomaterials were prepared by blending poly(epsilon-caprolactone) (PCL) with thermoplastic zein (TZ), a thermoplastic material obtained by de novo thermoplasticization of zein. Furthermore, to bioactivate the scaffolds, microparticles of osteoconductive hydroxyapatite (HA) were dispersed within the organic phases. Results demonstrated that materials and formulations strongly affected the micro-structural properties and hydrophilicity of the scaffolds and, therefore, had a pivotal role in guiding cell/scaffold interaction. In particular, if compared to neat PCL, PCL-HA composite and PCL/TZ blend, the three-phase PCL/TZ-HA showed improved MSCs adhesion, proliferation and osteogenic differentiation capability, thus demonstrating potential for bone regeneration. PMID: 20596759 [PubMed - as supplied by publisher] | | |
| Human melanoma-initiating cells express neural crest nerve growth factor receptor CD271.
July 3, 2010 at 1:16 PM
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| | Human melanoma-initiating cells express neural crest nerve growth factor receptor CD271. Nature. 2010 Jul 1;466(7302):133-137 Authors: Boiko AD, Razorenova OV, van de Rijn M, Swetter SM, Johnson DL, Ly DP, Butler PD, Yang GP, Joshua B, Kaplan MJ, Longaker MT, Weissman IL The question of whether tumorigenic cancer stem cells exist in human melanomas has arisen in the last few years. Here we show that in melanomas, tumour stem cells (MTSCs, for melanoma tumour stem cells) can be isolated prospectively as a highly enriched CD271(+) MTSC population using a process that maximizes viable cell transplantation. The tumours sampled in this study were taken from a broad spectrum of sites and stages. High-viability cells isolated by fluorescence-activated cell sorting and re-suspended in a matrigel vehicle were implanted into T-, B- and natural-killer-deficient Rag2(-/-)gammac(-/-) mice. The CD271(+) subset of cells was the tumour-initiating population in 90% (nine out of ten) of melanomas tested. Transplantation of isolated CD271(+) melanoma cells into engrafted human skin or bone in Rag2(-/-)gammac(-/-) mice resulted in melanoma; however, melanoma did not develop after transplantation of isolated CD271(-) cells. We also show that in mice, tumours derived from transplanted human CD271(+) melanoma cells were capable of metastatsis in vivo. CD271(+) melanoma cells lacked expression of TYR, MART1 and MAGE in 86%, 69% and 68% of melanoma patients, respectively, which helps to explain why T-cell therapies directed at these antigens usually result in only temporary tumour shrinkage. PMID: 20596026 [PubMed - as supplied by publisher] | | |
| Optimized multiparametric immunophenotyping of umbilical cord blood cells by flow cytometry.
July 3, 2010 at 1:16 PM
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| | Optimized multiparametric immunophenotyping of umbilical cord blood cells by flow cytometry. Nat Protoc. 2010 Jul;5(7):1337-1346 Authors: Basford C, Forraz N, McGuckin C Umbilical cord blood is a key source of stem cells for transplantation and regenerative medicine. To maximize each cord blood sample, it is important to analyze its cellular populations. Many cord blood banks focus on counts of total nucleated cells and/or cells that carry the CD34 antigen, but this limited focus does not give a true estimation of cord blood content, quality and appropriateness for use. This protocol is the first of its kind to enable a comprehensive investigation of cord blood cellular populations. Using multicolor flow cytometry it is possible to examine expression of 26 antigens-including hematopoietic markers CD45 and CD34, immune markers CD19 and CD3, and HLA-using a total of only 1 x 10(6) cells from each unit for both pre- and post-processing. The samples are stained, lysed, washed and analyzed flow cytometrically. This method also provides valuable information beyond cord blood composition and quality; for example, it can also be used to assess whether maternal factors affect CD34(+) cell numbers. Collection, processing, cryopreservation and initial flow cytometry take approximately 5 h. PMID: 20595961 [PubMed - as supplied by publisher] | | |
| Isolation of adipose-derived stem cells and their induction to a chondrogenic phenotype.
July 3, 2010 at 1:16 PM
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| | Isolation of adipose-derived stem cells and their induction to a chondrogenic phenotype. Nat Protoc. 2010 Jul;5(7):1294-1311 Authors: Estes BT, Diekman BO, Gimble JM, Guilak F The ability to isolate, expand and differentiate adult stem cells into a chondrogenic lineage is an important step in the development of tissue engineering approaches for cartilage repair or regeneration for the treatment of joint injury or osteoarthritis, as well as for their application in plastic or reconstructive surgery. Adipose-derived stem cells (ASCs) provide an abundant and easily accessible source of adult stem cells for use in such regenerative approaches. This protocol first describes the isolation of ASCs from liposuction aspirate. The cell culture conditions provided for ASC expansion provide a large number of multipotent stem cells. Instructions for growth factor-based induction of ASCs into chondrocyte-like cells using either cell pellet or alginate bead systems are detailed. These methods are similar to those published for chondrogenesis of bone marrow-derived mesenchymal stem cells but distinct because of the unique nature of ASCs. Investigators can expect consistent differentiation of ASCs, allowing for slight variation as a result of donor and serum lot effects. Approximately 10-12 weeks are needed for the entire process of ASC isolation, including the characterization of chondrocyte-like cells, which is also described. PMID: 20595958 [PubMed - as supplied by publisher] | | |
| Temporary Angiogenic Transformation of the Skin Graft Vasculature after Reperfusion.
July 3, 2010 at 1:16 PM
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| | Temporary Angiogenic Transformation of the Skin Graft Vasculature after Reperfusion. Plast Reconstr Surg. 2010 Jul;126(1):61-70 Authors: Lindenblatt N, Platz U, Althaus M, Hegland N, Schmidt CA, Contaldo C, Vollmar B, Giovanoli P, Calcagni M BACKGROUND:: In the era of tissue engineering, the physiologic process of skin graft revascularization remains unclear, preventing the successful development of skin substitutes. Therefore, the authors developed a new in vivo model with which to visualize the process of engraftment and its microvascular architecture. The aim of this study was to specifically investigate the vascular transformations within the skin graft to gain applicable knowledge on how vascular processes during engraftment occur. METHODS:: Microsurgical preparation of the modified dorsal skinfold chamber including autologous skin grafting was performed in male C57BL/6J mice (n = 10). In addition, immunohistochemistry of angiogenic factors, endothelial cells, and pericytes, and corrosion casting were performed to further characterize the specific mechanisms. RESULTS:: The graft exhibited capillary widening starting at day 3, resulting in the temporary formation of spherical protrusions at the graft capillary divisions starting in the center of the graft 24 to 48 hours after revascularization. Confocal microscopy showed the simultaneous expression of CD31 and desmin. Corrosion casting and evaluation by light microscopy and scanning electron microscopy showed the three-dimensional formation of capillaries in the wound bed that connected to the preexisting capillary loops of the skin graft. CONCLUSIONS:: The authors were able to show for the first time a temporary angiogenic response within the capillaries of the skin graft. This most likely represents a reaction to reperfusion allowing the supply of proangiogenic factors to the hypoxic skin graft. The detection of an angiogenic response within the graft capillaries is for the first time made possible in the newly developed model and is therefore completely novel. PMID: 20595857 [PubMed - as supplied by publisher] | | |
| Highly efficient lentiviral transduction of phenotypically and genotypically characterized endothelial progenitor cells from adult peripheral blood.
July 3, 2010 at 1:16 PM
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| | Highly efficient lentiviral transduction of phenotypically and genotypically characterized endothelial progenitor cells from adult peripheral blood. Blood Coagul Fibrinolysis. 2010 Jul;21(5):464-473 Authors: Stockschlaeder M, Shardakova O, Weber K, Stoldt VR, Fehse B, Giers G, Scharf RE Postnatal vasculogenesis has been implicated as an important mechanism for neovascularization via bone marrow-derived endothelial progenitor cells (EPCs) circulating in peripheral blood. In preparation of the utilization of EPCs in clinical protocols, we have generated blood-derived EPCs according to two established protocols by culturing either nonadherent mononuclear cells on fibronectin or adherent mononuclear cells on collagen. To explore the feasibility of these EPCs for their potential clinical use as target cells for genetic transduction to enhance their thromboresistance, newly designed retroviral and lentiviral gene ontology expression vectors were tested. Whereas cell clusters derived from the nonadherent cells demonstrated an only limited proliferative potential, cell colonies derived from collagen-adherent cells expanded more than a million-fold. Characterization of the exponentially growing cells by surface antigen and gene expression profiling revealed a consistently strong expression of characteristic endothelial markers, whereas expression of leukocyte markers was gradually lost. Using a single-step transduction protocol, we were able to achieve gene transfer efficiency of up to 99%. Our results suggest that the generated blood-derived EPC population might be attractive target cells for tissue engineering and gene therapy protocols due to their well defined phenotype, extensive proliferative potential, and efficient genetic transducibility, three important qualities that need to be defined prior to any clinical use. PMID: 20595824 [PubMed - as supplied by publisher] | | |
| Identification of a Structural Motif in the Tumor-Suppressive Protein GRIM-19 Required for Its Antitumor Activity.
July 3, 2010 at 1:16 PM
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| | Identification of a Structural Motif in the Tumor-Suppressive Protein GRIM-19 Required for Its Antitumor Activity. Am J Pathol. 2010 Jul 1; Authors: Nallar SC, Kalakonda S, Sun P, Ohmori Y, Hiroi M, Mori K, Lindner DJ, Kalvakolanu DV We have previously isolated GRIM-19, a novel growth suppressor, using a genetic method. GRIM-19 ablates cell growth by inhibiting the transcription factor signal transducer and activator of transcription 3 (STAT3). Up-regulation of STAT3 and growth promotion were observed in a number of human tumors. Although the tumor-suppressive actions of GRIM-19 are known, the structural elements required for its antitumor actions are not understood. Mutational and protein sequence analyses identified a motif in the N terminus of GRIM-19 that exhibited similarity to certain RNA viral proteins. We show that disruption of specific amino acids within this motif cripples the antitumor actions of GRIM-19. These mutants fail to interact with STAT3 efficiently and consequently do not inhibit growth-promoting gene expression. More importantly, we show that a clinically observed mutation in the N terminus of GRIM-19 also weakened its interaction with STAT3 and antitumor action. Together, these studies identify a major role for the N terminus of GRIM-19 in mediating its tumor-suppressive actions. PMID: 20595633 [PubMed - as supplied by publisher] | | |
| The New Concept of "Interventional Heart Failure Therapy": Part 2--Inotropes, Valvular Disease, Pumps, and Transplantation.
July 3, 2010 at 1:16 PM
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| | The New Concept of "Interventional Heart Failure Therapy": Part 2--Inotropes, Valvular Disease, Pumps, and Transplantation. J Cardiovasc Pharmacol Ther. 2010 Jul 1; Authors: Thompson KA, Philip KJ, Simsir S, Schwarz ER Recent advances in heart failure therapy include a variety of mechanical and device-based technologies that target structural aspects of heart failure that cannot be treated with drug therapy alone; these newer therapies can collectively be described as interventional heart failure therapy. This article is the second in a 2-part series reviewing interventional heart failure therapy. Interventions included in this discussion include those indicated for the treatment of end-stage refractory heart failure, including interventional medical therapy, interventional treatment of valvular disease, mechanical assist devices, and heart transplantation. Also included is a review of the currently available catheter-based pumps, which are intended to provide temporary support in patients with acute hemodynamic compromise. The use of cellular or stem cell therapy for the treatment of heart failure is an emerging interventional therapy and data supporting its use for the treatment heart failure will also be presented, as will a discussion of the role of palliative care and self-care in heart failure therapy. PMID: 20595625 [PubMed - as supplied by publisher] | | |
| Towards an optimized culture medium for the generation of mouse induced pluripotent stem cells.
July 3, 2010 at 1:16 PM
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| | Towards an optimized culture medium for the generation of mouse induced pluripotent stem cells. J Biol Chem. 2010 Jul 1; Authors: Chen J, Liu J, Han Q, Qin D, Xu J, Chen Y, Yang J, Song H, Yang D, Peng M, He W, Li R, Wang H, Gan Y, Ding K, Zeng L, Lai L, Esteban MA, Pei D Generation of induced pluripotent stem cells (iPSCs) from somatic cells using defined factors has potential relevant applications in regenerative medicine and biology. However, this promising technology remains inefficient and time consuming. We have devised a serum free culture medium termed iSF1 that facilitates the generation of mouse iPSCs. This optimization of the culture medium is sensitive to the presence of Myc in the reprogramming factors. Moreover, we could reprogram meningeal cells using only two factors Oct4/Klf4. Therefore, iSF1 represents a basal medium that may be used for mechanistic studies and testing new reprogramming approaches. PMID: 20595395 [PubMed - as supplied by publisher] | | |
| Induction of pluripotent stem cells from human third molar mesenchymal stromal cells.
July 3, 2010 at 1:16 PM
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| | Induction of pluripotent stem cells from human third molar mesenchymal stromal cells. J Biol Chem. 2010 Jul 1; Authors: Oda Y, Yoshimura Y, Ohnishi H, Tadokoro M, Katsube Y, Sasao M, Kubo Y, Hattori K, Saito S, Horimoto K, Yuba S, Ohgushi H The expression of four transcription factors (OCT3/4, SOX2, KLF4, and MYC) can reprogram mouse as well as human somatic cells to induced pluripotent stem (iPS) cells. We generated iPS cells from mesenchymal stromal cells (MSCs) derived from human third molars (wisdom teeth) by retroviral transduction of OCT3/4, SOX2, and KLF4 without MYC which is considered as oncogene. Interestingly, some of the clonally-expanded MSCs could be used for iPS cell generation with 30 to 100-fold higher efficiency compared to that of other clonally-expanded MSCs and human dermal fibroblasts. Global gene expression profiles demonstrated some up-regulated genes regarding DNA repair/histone conformational change in the efficient clones, suggesting that the processes of chromatin remodeling have important roles in the cascade of iPS cells generation. The generated iPS cells resembled human embryonic stem (ES) cells in many aspects, including morphology, ES markers expression, global gene expression, epigenetic states, and the ability to differentiate into the three germ layers in vitro and in vivo. Because human third molars are discarded as clinical waste, our data indicate that clonally expanded MSCs derived from human third molars are a valuable cell source for the generation of iPS cells. PMID: 20595386 [PubMed - as supplied by publisher] | | |
| Amyloid beta1-42 oligomer inhibits myelin sheet formation in vitro.
July 3, 2010 at 1:16 PM
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| | Amyloid beta1-42 oligomer inhibits myelin sheet formation in vitro. Neurobiol Aging. 2010 Jun 29; Authors: Horiuchi M, Maezawa I, Itoh A, Wakayama K, Jin LW, Itoh T, Decarli C Accumulating evidence indicates that white matter degeneration contributes to the neural disconnections that underlie Alzheimer's disease pathophysiology. Although this white matter degeneration is partly attributable to axonopathy associated with neuronal degeneration, amyloid beta (Abeta) protein-mediated damage to oligodendrocytes could be another mechanism. To test this hypothesis, we studied effects of soluble Abeta in oligomeric form on survival and differentiation of cells of the oligodendroglial lineage using highly purified oligodendroglial cultures from rats at different developmental stages. Abeta oligomer at 10 muM or higher reduced survival of mature oligodendrocytes, whereas oligodendroglial progenitor cells (OPCs) were relatively resistant to the Abeta oligomer-mediated cytotoxicity. Further study revealed that Abeta oligomer even at 1 muM accelerated 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) formazan exocytosis in mature oligodendrocytes, and, more significantly, inhibited myelin sheet formation after induction of in vitro differentiation of OPCs. These results imply a novel pathogenetic mechanism underlying Abeta oligomer-mediated white matter degeneration, which could impair myelin maintenance and remyelination by adult OPCs, resulting in accumulating damage to myelinating axons thereby contributing to neural disconnections. PMID: 20594620 [PubMed - as supplied by publisher] | | |
| Anisotropic Mechanical Properties of Collagen Hydrogels Induced by Uniaxial-Flow for Ocular Applications.
July 3, 2010 at 1:16 PM
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| | Anisotropic Mechanical Properties of Collagen Hydrogels Induced by Uniaxial-Flow for Ocular Applications. J Biomater Sci Polym Ed. 2010 Jun 30; Authors: Tanaka Y, Kubota A, Matsusaki M, Duncan T, Hatakeyama Y, Fukuyama K, Quantock AJ, Yamato M, Akashi M, Nishida K Engineering of well-organized tissue constructs is active in the field of material science for biomedical applications. Here, we propose a method for orienting collagen in transparent high-density collagen hydrogels using a simple rolling method. Structural organization and mechanical function were adjusted by regulating the thickness of the construct and the cross-linking reagent. Directionality of collagen alignment on the microscopic scale was achieved parallel to the extensional flow. The preferential alignment of collagen significantly affected the mechanical properties of the construct, with strong tensile strength in the direction parallel to the collagen, and high elastic strain in the perpendicular direction. The tensile strength in the parallel direction was effectively increased by 67% by increasing the cross-linking reagents by 33%, without affecting transparency which remained at 70-80% to visible light. The constructs exhibit good biocompatibility for as a substrate for the expansion of corneal epithelial cells isolated from human donor cornea, indicating the potential for tissue engineering and biomedical applications, particularly for ocular treatments. PMID: 20594419 [PubMed - as supplied by publisher] | | |
| Preparation of Interconnected Porous Chitosan Scaffolds by Sodium Acetate Particulate Leaching.
July 3, 2010 at 1:16 PM
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| | Preparation of Interconnected Porous Chitosan Scaffolds by Sodium Acetate Particulate Leaching. J Biomater Sci Polym Ed. 2010 Jun 30; Authors: Lim JI, Lee YK, Shin JS, Lim KJ For tissue-engineering applications, a 3D porous chitosan scaffold was simply prepared from a mixture of acidic chitosan solution and sodium acetate particles as the porogen by a salt-leaching method. Differences in the porous structure in terms of pore morphology and interconnectivity between the salt-leached chitosan scaffold and phase-separated scaffold as the control were examined by using scanning electron microscopy, protein release and enzymatic degradation tests. A fibroblast (NIH-3T3) cell culture was performed for cell affinity evaluation. The chitosan scaffold prepared by salt-leaching showed good interconnectivity and improved mechanical properties. Furthermore, the chitosan scaffolds showed a high initial cell adhesion after 4 h cell culture and increased cell proliferation than the control. Thus, salt-leached chitosan scaffolds can be used for various tissue-engineering applications. PMID: 20594410 [PubMed - as supplied by publisher] | | |
| Cryo DualBeam FIB-SEM to evaluate the interface between cells and nanopatterned scaffolds.
July 3, 2010 at 1:16 PM
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| | Cryo DualBeam FIB-SEM to evaluate the interface between cells and nanopatterned scaffolds. Tissue Eng Part C Methods. 2010 Jul 1; Authors: Jansen J, Lamers E, Walboomers XF, Domanski M, McKerr G, O'Hagan B, Barnes C, Peto L, Luttge R, Winnubst L, Gardeniers H With the advance of nanotechnology in biomaterials science and tissue engineering, it is essential that new techniques become available to visualize processes that take place at the direct interface between tissue and scaffold materials. Here, a cryo DualBeam scanning electron microscope (FIB-SEM) was used as a novel approach to visualize the interactions between frozen hydrated cells and nanometric structures in high detail. Through a comparison of images acquired with transmission electron microscopy (TEM), conventional FIB-SEM operated at ambient temperature and cryo DualBeam FIB-SEM, the advantages and disadvantages of each technique were evaluated. Ultrastructural details of both (extra)cellular components and cell organelles were best visualized with TEM. However, processing artifacts such as shrinkage of cells at the substrate interface were introduced in both TEM and conventional FIB-SEM. In addition, the cellular contrast in conventional FIB-SEM was low; consequently cells were difficult to distinguish from the adjoining substrate. Cryo DualBeam FIB-SEM did preserve (extra)cellular details like the contour, cell membrane and mineralized matrix. The three described techniques have proven to be complementary for the evaluation of processes that take place at the interface between tissue and substrate. PMID: 20594113 [PubMed - as supplied by publisher] | | |
| [Tissue engineering of the oral mucosa]
July 3, 2010 at 1:16 PM
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| | [Tissue engineering of the oral mucosa] Morfologiia. 2010;137(1):62-70 Authors: This review contains the systematized data on the development and application of tissue engineering methods to generate in vitro oral mucosa (OM) tissues and its full-thickness equivalents. The data are presented describing the cultivation of epithelial monolayers and stratified sheets and connective tissue component, as well as their unification into the tissue-engineered constructs reproducing the structure of native OM. The equivalents engineered in vitro are used as the transplants in the areas of the defects of OM, or of some other mucous membranes and the skin. They are also widely applied as test-systems for in vitro experiments conducted to assess the effect of various factors on OM. PMID: 20593591 [PubMed - in process] | | |
| Three dimensional multi-scale modelling and analysis of cell damage in cell-encapsulated alginate constructs.
July 3, 2010 at 1:16 PM
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| | Three dimensional multi-scale modelling and analysis of cell damage in cell-encapsulated alginate constructs. J Biomech. 2010 Apr 19;43(6):1031-8 Authors: Yan KC, Nair K, Sun W One of the major challenges in scaffold guided regenerative therapies is identifying the essential cues such as mechanical forces that induce cellular responses to form functional tissue. Developing multi-scale modelling methods would facilitate in predicting responses of encapsulated cells for controlling and maintaining the cell phenotype in an engineered tissue construct, when mechanical loads are applied. The objective of this study is to develop a 3D multi-scale numerical model for analyzing the stresses and deformations of the cell when the tissue construct is subjected to macro-scale mechanical loads and to predict load-induced cell damage. Specifically, this methodology characterizes the macro-scale structural behavior of the scaffold, and quantifies 3D stresses and deformations of the cells at the micro-scale and at a cellular level, wherein individual cell components are incorporated. Assuming that cells have inherent ability to sustain a critical load without damage, a damage criterion is established and a stochastic simulation is employed to predict the percentage cell viability within the tissue constructs. Bio-printed cell-alginate tissue constructs were tested with 1%, 5% and 10% compression strain applied and the cell viability were characterized experimentally as 23.2+/-16.8%, 9.0+/-5.4% and 4.6+/-2.1%. Using the developed method, the corresponding micro-environments of the cells were analyzed, the mean critical compressive strain was determined as 0.5%, and the cell viability was predicted as 26.6+/-7.0, 13.3+/-4.5, and 10.1+/-2.8. The predicted results capture the trend of the damage observed from the experimental study. PMID: 20096842 [PubMed - indexed for MEDLINE] | | |
| Bioprocessing of human glioblastoma brain cancer tissue.
July 3, 2010 at 1:16 PM
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| | Bioprocessing of human glioblastoma brain cancer tissue. Tissue Eng Part A. 2010 Apr;16(4):1169-77 Authors: Panchalingam KM, Paramchuk WJ, Chiang CY, Shah N, Madan A, Hood L, Foltz G, Behie LA Solid cancer tumors are thought to arise from aberrant stem cell populations, called cancer stem cells (CSCs). Hence, the development of effective cancer therapies may rely on developing methods that specifically target these cells. However, the scarcity of CSCs in vivo represents a major impediment to such research, as there is an insufficient supply for basic biochemical and genetic analyses. It is therefore necessary to develop methods to expand reproducibly CSC tissue in vitro in a controlled environment. To date, we have developed bioreactor protocols for the suspension culture of an aggressive and deadly type of brain cancer called glioblastoma multiforme (GBM). Human GBM-derived cells achieved a maximum cell density of 2.4 x 10(6) cells/mL after 24 days under high shear conditions in batch culture conditions. In comparison, fed-batch cultures achieved 4.5 x 10(6) cells/mL after 32 days. Characterization of bioreactor-expanded cells using both flow cytometry and a differentiation assay indicated that bioreactor-generated human GBM-derived cells have similar characteristics to the initial cell population and achieve >90% CD133 expression. Additionally, genomic characterization indicated that a very small number of key genes were differentially expressed in the bioreactor-expanded GBM-derived cells, thereby conserving the basic nature of the brain cancer tissue in the cell expansion process. PMID: 20021271 [PubMed - indexed for MEDLINE] | | |
| Reversine enhances generation of progenitor-like cells by dedifferentiation of annulus fibrosus cells.
July 3, 2010 at 1:16 PM
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| | Reversine enhances generation of progenitor-like cells by dedifferentiation of annulus fibrosus cells. Tissue Eng Part A. 2010 Apr;16(4):1443-55 Authors: Saraiya M, Nasser R, Zeng Y, Addya S, Ponnappan RK, Fortina P, Anderson DG, Albert TJ, Shapiro IM, Risbud MV The aim of this study was to determine if treatment with reversine, a purine analog, promoted generation of skeletal progenitor cells from lineage-committed annulus fibrosus cells. Reversine modulated cell growth, morphology, and the actin cytoskeleton of annulus fibrosus cells. Microarray profiling coupled with Ingenuity Pathway Analysis revealed that reversine treatment resulted in a significant expression change in many genes including those required for cell-cell interaction, cell movement, cell growth, and development. Further analysis revealed that there was involvement of gene networks concerned with cellular assembly and organization, DNA replication and repair, tissue morphology, and cell-to-cell signaling. The gene expression profile was dependent on reversine concentration. In osteogenic media, cells pretreated with 300 nM reversine exhibited an increased induction in alkaline phosphatase activity and enhanced expression of alkaline phosphatase, bone sialoprotein, osteocalcin, and collagen type I mRNA. Maintained in adipogenic media, the reversine-pretreated annulus cells displayed evidence of adipogenic differentiation: accumulation of cytosolic lipid droplets and increased expression of PPAR-gamma2, LPL, and Fabp mRNA. In chondrogenic media, cells pretreated with reversine exhibited marked increase in the induction of aggrecan, collagen types II, IX, and XI, and versican. It is concluded that reversine treatment induced annulus fibrosus cell plasticity and promoted their differentiation along mesenchymal lineages. This agent could be used to generate skeletal progenitor cells to orchestrate the repair of the intervertebral disc. PMID: 19947906 [PubMed - indexed for MEDLINE] | | |
| Generation of human skin equivalents under submerged conditions-mimicking the in utero environment.
July 3, 2010 at 1:16 PM
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| | Generation of human skin equivalents under submerged conditions-mimicking the in utero environment. Tissue Eng Part A. 2010 Apr;16(4):1433-41 Authors: Thakoersing VS, Ponec M, Bouwstra JA In this study we generated human skin equivalents (HSEs) under submerged conditions mimicking the aqueous in utero environment and investigated the morphology and differentiation process of the formed epidermis. Further, the skin barrier, which resides in the stratum corneum (SC), was characterized by its lipid content, hydration level, and natural moisturizing factor level. The submerged HSEs showed comparable tissue morphology and similar expression of several differentiation markers and SC lipid composition compared with HSEs grown at the air-liquid interface and native human skin. The SC of the submerged HSEs, however, contained more free water and less natural moisturizing factors compared with the air-exposed counterparts. These results show that the presented cell culture method can be utilized to generate HSEs under submerged conditions to study epidermal formation under aqueous conditions. PMID: 19929321 [PubMed - indexed for MEDLINE] | | |
| Functional assessment of skeletal muscle regeneration utilizing homologous extracellular matrix as scaffolding.
July 3, 2010 at 1:16 PM
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| | Functional assessment of skeletal muscle regeneration utilizing homologous extracellular matrix as scaffolding. Tissue Eng Part A. 2010 Apr;16(4):1395-405 Authors: Merritt EK, Hammers DW, Tierney M, Suggs LJ, Walters TJ, Farrar RP The loss of a portion of skeletal muscle poses a unique challenge for the normal regeneration of muscle tissue. A transection injury with tissue loss will not heal due to the gap between muscle segments. A damage model was developed by removing a portion of the lateral gastrocnemius (GAS) of Sprague-Dawley rats. Maximal isometric, tetanic tension (P(o)) was measured after the removal of either a small defect (0.5 x 1.0 cm) or a large defect (1.0 x 1.0 cm) piece of the GAS. In situ P(o) immediately after creation of the defect was 88.3 +/- 2.0% of the nonoperated contralateral GAS force for small defect and 76.9 +/- 3.2% of control for large defect. No functional recovery occurred in either group over the course of 28 days. To enhance recovery, a homologous, decellularized, muscle extracellular matrix (ECM) was implanted into the 1 x 1 cm defect of the lateral GAS of Lewis rats. After 42 days, growth of blood vessels and myofibers into the ECM was apparent, but no restoration of P(o) occurred. These data demonstrate the ability of the ECM to support muscle and blood vessel regeneration, but full recovery of function does not occur after 42 days. PMID: 19929169 [PubMed - indexed for MEDLINE] | | |
| Adipose-derived stem cell delivery into collagen gels using chitosan microspheres.
July 3, 2010 at 1:16 PM
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| | Adipose-derived stem cell delivery into collagen gels using chitosan microspheres. Tissue Eng Part A. 2010 Apr;16(4):1369-84 Authors: Natesan S, Baer DG, Walters TJ, Babu M, Christy RJ Integration of stem cells to injured tissues requires an appropriate delivery device and scaffolding system. In the present study we have developed an in vitro strategy to load and release adipose-derived mesenchymal stem cells (ASC) from chitosan microspheres (CSM) into a collagen gel scaffold. Porous CSM of uniform size and composition were prepared and used as a stem cell carrier. ASC were allowed to attach to the microspheres and infiltrate through the microsphere pores. The number of viable cells was counted in vitro, using MTT and Calcein acetoxymethyl ester (AM) assays, and it showed a proportional increase with seeding density and reached a maximum cell number by 24 h. The cells inside the microspheres remained metabolically active and viable, could be retrieved from the spheres, and maintained expression of stem-cell-specific markers. Electron microscopic evaluation of the cell-microsphere complex showed that the CSM were able to support cell attachment and that the cells had infiltrated into the pores of the microspheres. The ability of the cells to proliferate and differentiate into adipogenic- and osteogenic-like precursors indicates that the cells have maintained their multipotency after migration out of the microspheres. To mimic cell delivery into a tissue, ASC-loaded CSM were embedded in type-1 collagen scaffold by mixing them with type-1 collagen solution while inducing gelation. By 14 days the cells released into the collagen gel and were able to populate the entire scaffold. When observed through transmission electron microscopy, the cells align along the collagen fibrils with a characteristic fibroblast-like morphology. This study provides a model to capture pluripotent stem cells, expand their cell number within a biomaterial scaffold in vitro, and deliver within an appropriate matrix to repair damaged tissue. PMID: 19916819 [PubMed - indexed for MEDLINE] | | |
| Hepatic differentiation of mouse embryonic stem cells in three-dimensional polymer scaffolds.
July 3, 2010 at 1:16 PM
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| | Hepatic differentiation of mouse embryonic stem cells in three-dimensional polymer scaffolds. Tissue Eng Part A. 2010 Apr;16(4):1115-22 Authors: Liu T, Zhang S, Chen X, Li G, Wang Y Embryonic stem cells (ESCs) can have unlimited proliferation potential and the capability to differentiate into almost all types of tissues. The use of ESCs as a novel source of hepatocytes has therefore recently received much attention. To date, however, the efficient and mass differentiation of ESCs into hepatocytes in vitro has been proven to be difficult. In this study, we investigated a three-dimensional (3D) mouse ESC hepatic differentiation system. Cells derived from 5-day-old embryoid bodies were mixed with Matrigel and immediately seeded in a biodegradable polymer scaffold composed of poly-l-lactic acid and polyglycolic acid. Exogenous growth factors and hormones were added sequentially for 20 days to promote hepatic histogenesis. The system enabled spontaneous spheroid formation and mass cultivation of embryoid body-derived cells. The 3D differentiated hepatocyte-like cells were able to express several liver-specific markers and proteins, secrete albumin, store glycogen, and allow the uptake of low-density lipoproteins. These findings suggest that this supportive 3D environment with appropriate inducing factors could provide mouse ESC-derived cells with an environment closely mimicking that of hepatogenesis in vivo. PMID: 19916802 [PubMed - indexed for MEDLINE] | | |
| Interactive cytokine regulation of synoviocyte lubricant secretion.
July 3, 2010 at 1:16 PM
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| | Interactive cytokine regulation of synoviocyte lubricant secretion. Tissue Eng Part A. 2010 Apr;16(4):1329-37 Authors: Blewis ME, Lao BJ, Schumacher BL, Bugbee WD, Sah RL, Firestein GS Cytokine regulation of synovial fluid (SF) lubricants, hyaluronan (HA), and proteoglycan 4 (PRG4) is important in health, injury, and disease of synovial joints, and may also provide powerful regulation of lubricant secretion in bioreactors for articulating tissues. This study assessed lubricant secretion rates by human synoviocytes and the molecular weight (MW) of secreted lubricants in response to interleukin (IL)-1beta, IL-17, IL-32, transforming growth factor-beta 1 (TGF-beta1), and tumor necrosis factor-alpha (TNF-alpha), applied individually and in all combinations. Lubricant secretion rates were assessed using ELISA and binding assays, and lubricant MW was assessed using gel electrophoresis and Western blotting. HA secretion rates were increased approximately 40-fold by IL-1beta, and increased synergistically to approximately 80-fold by the combination of IL-1beta + TGF-beta1 or TNF-alpha + IL-17. PRG4 secretion rates were increased approximately 80-fold by TGF-beta1, and this effect was counterbalanced by IL-1beta and TNF-alpha. HA MW was predominantly <1 MDa for controls and individual cytokine stimulation, but was concentrated at >3 MDa after stimulation by IL-1beta + TGF-beta1 + TNF-alpha to resemble the distribution in human SF. PRG4 MW was unaffected by cytokines and similar to that in human SF. These results contribute to an understanding of the relationship between SF cytokine and lubricant content in health, injury, and disease, and provide approaches for using cytokines to modulate lubricant secretion rates and MW to help achieve desired lubricant composition of fluid in bioreactors. PMID: 19908966 [PubMed - indexed for MEDLINE] | | |
| Ascorbic acid improves embryonic cardiomyoblast cell survival and promotes vascularization in potential myocardial grafts in vivo.
July 3, 2010 at 1:16 PM
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| | Ascorbic acid improves embryonic cardiomyoblast cell survival and promotes vascularization in potential myocardial grafts in vivo. Tissue Eng Part A. 2010 Apr;16(4):1349-61 Authors: Martinez EC, Wang J, Gan SU, Singh R, Lee CN, Kofidis T Organ restoration via cell therapy and tissue transplantation is limited by impaired graft survival. We tested the hypothesis that ascorbic acid (AA) reduces cell death in myocardial grafts both in vitro and in vivo and introduced a new model of autologous graft vascularization for later transplantation. Luciferase (Fluc)- and green fluorescent protein (GFP)-expressing H9C2 cardiomyoblasts were seeded in gelatin scaffolds to form myocardial artificial grafts (MAGs). MAGs were supplemented with AA (5 or 50 mumol/L) or plain growth medium. Bioluminescence imaging showed increased cell photon emission from day 1 to 5 in grafts supplemented with 5 mumol/L (p < 0.001) and 50 mumol/L (p < 0.01) AA. The amount of apoptotic cells in plain MAGs was significantly higher than in AA-enriched grafts. In our in vitro model, AA also enhanced H9C2 cell myogenic differentiation. For in vivo studies, MAGs containing H9C2-GFP-Fluc cells and enriched with AA (n = 10) or phosphate-buffered saline (n = 10) were implanted in the renal pouch of Wistar rats. At day 6, postimplantation bioluminescence signals decreased by 74% of baseline in plain MAGs versus 36% in AA-enriched MAGs (p < 0.0001). AA grafts contained significantly higher amounts of blood vessels, GFP(+) donor cells, and endothelial cells. In this study, we identified AA as a potent supplement that improves cardiomyoblast survival and promotes neovascularization in bioartificial grafts. PMID: 19908964 [PubMed - indexed for MEDLINE] | | |
| Self-assembly of aligned tissue-engineered annulus fibrosus and intervertebral disc composite via collagen gel contraction.
July 3, 2010 at 1:16 PM
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| | Self-assembly of aligned tissue-engineered annulus fibrosus and intervertebral disc composite via collagen gel contraction. Tissue Eng Part A. 2010 Apr;16(4):1339-48 Authors: Bowles RD, Williams RM, Zipfel WR, Bonassar LJ Many cartilaginous tissues such as intervertebral disc (IVD) display a heterogeneous collagen microstructure that results in mechanical anisotropy. These structures are responsible for mechanical function of the tissue and regulate cellular interactions and metabolic responses of cells embedded within these tissues. Using collagen gels seeded with ovine annulus fibrosus cells, constructs of varying structure and heterogeneity were created to mimic the circumferential alignment of the IVD. Alignment was induced within gels by contracting annular gels around an inner boundary using both a polyethylene center and alginate center to create a composite engineered IVD. Collagen alignment and heterogeneity were measured using second harmonic generation microscopy. Decreasing initial collagen density from 2.5 mg/mL to 1 mg/mL produced greater contraction of constructs, resulting in gels that were 55% and 6.2% of the original area after culture, respectively. As a result, more alignment occurred in annular-shaped 1 mg/mL gels compared with 2.5 mg/mL gels (p < 0.05). This alignment was also produced in a composite-engineered IVD with alginate nucleus pulposus. The resulting collagen alignment could promote further aligned collagen development necessary for the creation of a mechanically functional tissue-engineered IVD. PMID: 19905878 [PubMed - indexed for MEDLINE] | | |
| Electrospun silk fibroin scaffolds with macropores for bone regeneration: an in vitro and in vivo study.
July 3, 2010 at 1:16 PM
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| | Electrospun silk fibroin scaffolds with macropores for bone regeneration: an in vitro and in vivo study. Tissue Eng Part A. 2010 Apr;16(4):1271-9 Authors: Park SY, Ki CS, Park YH, Jung HM, Woo KM, Kim HJ We developed three-dimensional electrospun silk fibroin (ESF) scaffolds with controllable pore size. The purpose of this study was to evaluate ESF scaffolds with pores (P-ESF) for bone regeneration via in vitro and in vivo studies, with a comparison to a commercially available porous three-dimensional polylactic acid (PLA) scaffold. P-ESF supported significantly higher proliferation and alkaline phosphatase activity of osteoblasts than PLA in vitro (p < 0.05). Moreover, higher expression levels of activated adhesion-related proteins, including focal adhesion kinase, were observed in the P-ESF than in PLA, as confirmed by western blot analyses. Microcomputed tomography revealed that 78.30% of the original bone volume was attained in the P-ESF implantation group at 7 weeks after critical bone defect formation in rat calvaria. Comparatively, the PLA implantation group showed only 49.31%. Histological evaluation also showed new bone tissue formation upon P-ESF implantation. Taken together, the P-ESF scaffold may be a good bone substitute for bone regeneration. PMID: 19905876 [PubMed - indexed for MEDLINE] | | |
| Controlled release of bone morphogenetic protein-2 enhances recruitment of osteogenic progenitor cells for de novo generation of bone tissue.
July 3, 2010 at 1:16 PM
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| | Controlled release of bone morphogenetic protein-2 enhances recruitment of osteogenic progenitor cells for de novo generation of bone tissue. Tissue Eng Part A. 2010 Apr;16(4):1263-70 Authors: Kimura Y, Miyazaki N, Hayashi N, Otsuru S, Tamai K, Kaneda Y, Tabata Y The objective of this study was to evaluate the cellular contribution to the phenomenon of de novo generation of bone tissue induced by the controlled release of bone morphogenetic protein-2 (BMP-2). Gelatin hydrogels (2 mg) incorporating BMP-2 (3 microg) with different water contents were subcutaneously implanted into the back of enhanced green fluorescent protein-chimeric mice to induce the ectopic de novo generation of bone tissue. The hydrogels incorporating BMP-2 could release BMP-2 at different time profiles. When evaluated radiologically and histologically, the ectopic de novo generation of bone tissue was induced by the controlled release of BMP-2 from the hydrogels around the hydrogel-implanted site. The relative percentage number of green fluorescent protein- to osteocalcin-positive cells recruited into the de novo generated bone tissue depended on the BMP-2 release profile. The higher the percentage, the stronger was the de novo generation of bone tissue. These findings indicate that bone marrow-derived osteoblast progenitor cells were recruited from the blood circulation by BMP-2 release and consequently contributed to the ectopic de novo generation of bone tissue. It is conceivable that the local concentration of BMP-2 modifies the recruitment profile of progenitor cells with an osteogenic potential around the release site of BMP-2, resulting in regulated volume of de novo generated bone tissue. PMID: 19886805 [PubMed - indexed for MEDLINE] | | |
| Heparin-conjugated fibrin as an injectable system for sustained delivery of bone morphogenetic protein-2.
July 3, 2010 at 1:16 PM
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| | Heparin-conjugated fibrin as an injectable system for sustained delivery of bone morphogenetic protein-2. Tissue Eng Part A. 2010 Apr;16(4):1225-33 Authors: Yang HS, La WG, Bhang SH, Jeon JY, Lee JH, Kim BS Long-term release of bone morphogenetic protein-2 (BMP-2) can promote bone regeneration. We developed an injectable system for long-term delivery of BMP-2 by covalently conjugating heparin to fibrinogen. The heparin-conjugated fibrinogen formed an injectable, heparin-conjugated fibrin (HCF) gel when mixed with thrombin. HCF released 89.4 +/- 3.8% of the loaded BMP-2 for 13 days, whereas normal fibrin released 83.7 +/- 7.6% for the initial 3 days. BMP-2 released from HCF significantly increased alkaline phosphatase activity of cultured osteoblasts, whereas BMP-2 released from normal fibrin did not do so, indicating that BMP-2 released from HCF is bioactive and suggesting that long-term delivery of BMP-2 is advantageous over short-term delivery for bone regeneration. HCF, BMP-2-loaded HCF, and BMP-2-loaded normal fibrin containing free heparin were contained in polyester cylindrical tubes and implanted into the hind limb muscle pockets of rats for 8 weeks. Soft X-ray radiography, computed tomography, histomorphometry, calcium assay, and western blot analysis showed that BMP-2-loaded HCF yielded the most extensive bone formation among the groups. Since HCF can deliver BMP-2 over a long term, is an injectable system, and is made of clinically benign materials, this system would have advantages for clinical applications to regenerate bone. PMID: 19886733 [PubMed - indexed for MEDLINE] | | |
| A hyaluronate-atelocollagen/beta-tricalcium phosphate-hydroxyapatite biphasic scaffold for the repair of osteochondral defects: a porcine study.
July 3, 2010 at 1:16 PM
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| | A hyaluronate-atelocollagen/beta-tricalcium phosphate-hydroxyapatite biphasic scaffold for the repair of osteochondral defects: a porcine study. Tissue Eng Part A. 2010 Apr;16(4):1189-200 Authors: Im GI, Ahn JH, Kim SY, Choi BS, Lee SW The authors had devised a novel biphasic scaffold combining hyaluronic acid and atelocallagen for the chondral phase and combining hydroxyapatite and beta-tricalcium phosphate for the osseous phase. Sixty-four osteochondral defects were created in the knee joints of 16 minipigs to evaluate the effectiveness of this scaffold for repairing cartilage in a large animal model. The defects were divided into five groups according to their treatment: filling with a cell/biphasic scaffold composite (Group I, 16 defects); implanting only the biphasic scaffold (Group II, 16 defects); placing the removed osteochondral fragments back into the defect (Group IIIa, 8 defects); autologous chondrocyte implantation (Group IIIb, 8 defects); leaving the defects empty (Group IV, the negative control). After 5 months, the International Cartilage Repair Society Macroscopic Score was similar in Group I (9.0), Group II (9.1), and Group IIIa (9.1), followed by Group IIIb (7.4) and Group IV (6.2). Except for three defects noted in Group IV, all the defects were filled with cartilaginous or fibrous tissue depending on the groups. The junction to the adjacent native cartilage was detectable in all the groups of minipigs. Microscopically, Group II had the highest score from the International Cartilage Repair Society Visual Histological Assessment Scale. The indentation study showed that the maximum loads and time constant of Group I, II, and IIIa defects were comparable to that of native cartilage, whereas the equilibrium loads of these groups were slightly greater than that of native cartilage. In conclusion, our results suggest that a biphasic osteochondral scaffold with a chondral phase, consisting of hyaluronate and atelocollagen, and an osseous phase, consisting of hydroxyapatite and beta-tricalcium phosphate, is effective for repairing osteochondral defects in a large animal model. PMID: 19883204 [PubMed - indexed for MEDLINE] | | |
| Repair of rat mandibular bone defects by alveolar osteoblasts in a novel plasma-derived albumin scaffold.
July 3, 2010 at 1:16 PM
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| | Repair of rat mandibular bone defects by alveolar osteoblasts in a novel plasma-derived albumin scaffold. Tissue Eng Part A. 2010 Apr;16(4):1179-87 Authors: Gallego L, Junquera L, GarcÃa E, GarcÃa V, Alvarez-Viejo M, Costilla S, Fresno MF, Meana A Repair of bone deficiencies in the craniofacial skeleton remains a difficult clinical problem. The aim of this study was to evaluate a novel albumin scaffold seeded with human alveolar osteoblasts and implanted into experimental mandibular defects. An experimental solid protein scaffold was prepared with human plasmatic albumin crossed with a glutaraldehyde-type agent. Microstructure of scaffold and mechanical properties were examined using scanning electron microscopy and a stress-controlled rheometer. Bilateral critical mandibular defects were created in eight immunodeficient rats. Defects of the right side of the mandibles received the cell-scaffold construct in all animals. All left mandibular defects were left untreated as blank controls. Sections of the defects were collected at 5, 8, and 11 weeks postsurgery and processed for histological and immunohistochemical observation, computed tomography examination, and computed tomography digital analysis. Histologically, bone formation was observed in both groups at 5 weeks postsurgery, and the engineered bone became more mature after 8 and 11 weeks, which was similar to normal bone. The origin of bone-forming cells within the defects and the localization of implanted human osteoblasts were confirmed by human vimentin expression. No bone formation could be observed at any control defect. Bone density after 8 weeks was significantly higher than that of the 5-week group (p = 0.02), and significant differences were also observed between 8 and 11 weeks (p < 0.01). The results indicate the clinical feasibility of albumin scaffold loaded with human alveolar cells and that it can be used as a good alternative for bone regeneration. PMID: 19863256 [PubMed - indexed for MEDLINE] | | |
| Role of the N- and C-terminal fragments of parathyroid-hormone-related protein as putative therapies to improve bone regeneration under high glucocorticoid treatment.
July 3, 2010 at 1:16 PM
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| | Role of the N- and C-terminal fragments of parathyroid-hormone-related protein as putative therapies to improve bone regeneration under high glucocorticoid treatment. Tissue Eng Part A. 2010 Apr;16(4):1157-68 Authors: de Castro LF, Lozano D, DapÃa S, Portal-Núñez S, Caeiro JR, Gómez-Barrena E, Esbrit P The parathyroid-hormone-related protein (PTHrP) is an important modulator of bone formation and bone remodeling. High and/or prolonged glucocorticoid (GC) treatments inhibit PTHrP expression in osteoblastic cells and bone formation and repair. We assessed the ability of the N- and C-terminal PTHrP fragments to restore the GC-altered bone regeneration after bone marrow ablation in mice. Animals were administered 3-methylprednisolone or vehicle and PTHrP (1-36) or PTHrP (107-139) every other day, beginning 4 days before marrow ablation in the tibia, and euthanized 12 days later. GC-treated mice showed in the ablated tibia a decrease in bone formation and in osteoblast and sclerostin-positive osteocyte numbers, reduced expression of osteoblastic factors, decreased osteogenesis of bone-marrow-derived cells, an increase in the numbers of multinucleated osteoclasts and adipocytes, and decreased cortical vascularization, as well as altered bone structure (measured by microcomputerized tomography) in the intact femur. These effects were reversed at least in part by either PTHrP peptide. The present novel findings support the use of both PTHrP peptides tested as putative bone regenerative therapies in GC-related bone diseases. PMID: 19860552 [PubMed - indexed for MEDLINE] | | |
| Directed growth of adult human white matter stem cell-derived neurons on aligned fibrillar collagen.
July 3, 2010 at 1:16 PM
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| | Directed growth of adult human white matter stem cell-derived neurons on aligned fibrillar collagen. Tissue Eng Part A. 2010 Apr;16(4):1103-13 Authors: Lanfer B, Hermann A, Kirsch M, Freudenberg U, Reuner U, Werner C, Storch A The nanoscale spatial organization of collagen fibrils as major constituents of extracellular matrices is believed to be crucial for neurite guidance in neural development and repair. To systematically study the influence of collagen fibril alignment, length, and density on human neuronal cell behavior, we used our novel technology to produce aligned collagen matrices by shear flow deposition using a microfluidic channel system and applied these surfaces to functional human neurons and glia derived from white matter neural stem cell cultures. Neurites on aligned collagen were highly oriented in the direction of the underlying fibrils, whereas neurites on nonaligned collagen or poly-d-lysine did not exhibit a preferred direction but formed a web-like morphology. Although the best alignment of collagen fibers in our study was seen using long fibrils at low density, the best neurite orientation was achieved on long fibrils at high density. Neurite outgrowth was enhanced on aligned collagen compared with nonaligned collagen or poly-d-lysine substrates, whereas neural differentiation and cell survival were not influenced by the type of substrate. Our data show that size and density of aligned collagen fibrils are crucial for axonal sprouting of human neural stem cell-derived neurons. The flexibility of our technology, allowing collagen matrix qualities to be adapted to the neuronal cell type of interest, is thus a major advantage for therapeutic reconstruction of axonal pathways in the central or peripheral nervous system. PMID: 19860550 [PubMed - indexed for MEDLINE] | | |
| Peritoneal cavity as bioreactor to grow autologous tubular urethral grafts in a rabbit model.
July 3, 2010 at 1:16 PM
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| | Peritoneal cavity as bioreactor to grow autologous tubular urethral grafts in a rabbit model. World J Urol. 2010 Apr;28(2):227-32 Authors: Gu GL, Zhu YJ, Xia SJ, Zhang J, Jiang JT, Hong Y, Liu GH PURPOSE: To investigate whether peritoneal cavity could function as bioreactor to produce autologous tubular grafts for urethral reconstruction in male rabbits. METHODS: 8Fr silastic tubes were implanted into peritoneal cavities of nine male rabbits. By 2 weeks, tubes were harvested and the tubular tissue covering the tubes was everted. A pendulous urethral segment of 1.5 cm long was totally excised and urethroplasty was performed with the everted tubular tissue in an end-to-end fashion. Another nine male rabbits underwent the same urethral resection and re-anastomosis as controls. Urethrography was performed at 1, 2 and 6 months postoperatively. Meanwhile, the neo-urethra were harvested and analyzed grossly and histologically. RESULTS: Histological analysis of the tubular tissue demonstrated transversely arranged myofibroblasts embedded in homogeneous collagen bundles and an outer layer of mesothelium. The tissue was easily everted and successfully transplanted as a urethral graft. Serial urethrography indicated no stricture or diverticula formation. While all animals of the control group developed stricture. Histological analysis of the neo-urethra demonstrated normal urethral architecture by 1 month, composed of multi-layers of urothelium surrounded by smooth muscle bundles, which became increasingly organized with time. By 6 months, the neo-urethra could be hardly distinguished from native urethra both grossly and histologically. CONCLUSIONS: These results show that the autologous tissue grown within the recipients' peritoneal cavity can be used successfully for tubularized urethral reconstruction in male rabbits. PMID: 19588153 [PubMed - indexed for MEDLINE] | | |
| Comparative characterization of mesenchymal stem cells from different age groups of cynomolgus monkeys.
July 3, 2010 at 1:16 PM
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| | Comparative characterization of mesenchymal stem cells from different age groups of cynomolgus monkeys. Sci China Life Sci. 2010 May;53(5):563-572 Authors: Ren Z, Wang J, Zou C, Guan Y, Zhang YA Bone marrow mesenchymal stem cells (BM-MSCs) are a potential tool for cell therapy and tissue engineering. In this study, we carried on a comparative study of the characteristics of MSCs from different age cynomolgus monkeys. A variety of factors, including donor age, must be considered before further applications, and various tests should be used to properly assess MSCs before the clinical application, especially when a prolonged culture and ex vivo expansion is necessary. PMID: 20596939 [PubMed - as supplied by publisher] | | | | 
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