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| Induction of complete and molecular remissions in acute myeloid leukemia by Wilms' tumor 1 antigen-targeted dendritic cell vaccination.
July 16, 2010 at 8:14 AM
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| | Induction of complete and molecular remissions in acute myeloid leukemia by Wilms' tumor 1 antigen-targeted dendritic cell vaccination. Proc Natl Acad Sci U S A. 2010 Jul 14; Authors: Van Tendeloo VF, Van de Velde A, Van Driessche A, Cools N, Anguille S, Ladell K, Gostick E, Vermeulen K, Pieters K, Nijs G, Stein B, Smits EL, Schroyens WA, Gadisseur AP, Vrelust I, Jorens PG, Goossens H, de Vries IJ, Price DA, Oji Y, Oka Y, Sugiyama H, Berneman ZN Active immunization using tumor antigen-loaded dendritic cells holds promise for the adjuvant treatment of cancer to eradicate or control residual disease, but so far, most dendritic cell trials have been performed in end-stage cancer patients with high tumor loads. Here, in a phase I/II trial, we investigated the effect of autologous dendritic cell vaccination in 10 patients with acute myeloid leukemia (AML). The Wilms' tumor 1 protein (WT1), a nearly universal tumor antigen, was chosen as an immunotherapeutic target because of its established role in leukemogenesis and superior immunogenic characteristics. Two patients in partial remission after chemotherapy were brought into complete remission after intradermal administration of full-length WT1 mRNA-electroporated dendritic cells. In these two patients and three other patients who were in complete remission, the AML-associated tumor marker returned to normal after dendritic cell vaccination, compatible with the induction of molecular remission. Clinical responses were correlated with vaccine-associated increases in WT1-specific CD8(+) T cell frequencies, as detected by peptide/HLA-A*0201 tetramer staining, and elevated levels of activated natural killer cells postvaccination. Furthermore, vaccinated patients showed increased levels of WT1-specific IFN-gamma-producing CD8(+) T cells and features of general immune activation. These data support the further development of vaccination with WT1 mRNA-loaded dendritic cells as a postremission treatment to prevent full relapse in AML patients. PMID: 20631300 [PubMed - as supplied by publisher] | | |
| Retargeting of adenovirus vectors through genetic fusion of a single-chain or single-domain antibody to capsid protein IX.
July 16, 2010 at 8:14 AM
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| | Retargeting of adenovirus vectors through genetic fusion of a single-chain or single-domain antibody to capsid protein IX. J Virol. 2010 Jul 14; Authors: Poulin KL, Lanthier RM, Smith AC, Christou C, Quiroz MR, Powell KL, O'Meara RW, Kothary R, Lorimer IA, Parks RJ Adenovirus (Ad) vectors are the most commonly used system for gene therapy applications due in part to its ability to infect a wide array of cell types and tissues. However, many therapies would benefit from the ability to target the Ad vector only to specific cells such as tumor cells for cancer gene therapy. In this study, we investigate the utility of capsid protein IX (pIX) as a platform for the presentation of single-chain (scFv) and single-domain (sdAb) antibodies for virus retargeting. We show that scFv can be displayed on the capsid through genetic fusion to native pIX, but these molecules fail to retarget the virus due to improper folding of the scFv. Redirecting expression of the fusion protein to the endoplasmic reticulum (ER) results in correct folding of the scFv and allows it to recognize its epitope; however, ER-targeted pIX-scFv were incorporated into the Ad capsid at a very low level which was not sufficient to retarget virus infection. In contrast, a pIX-sdAb was efficiently incorporated into the Ad capsid and enhanced virus infection of cells expressing the targeted receptor. Taken together, our data indicates that pIX is an effective platform for presentation of large targeting polypeptides on the surface of the virus capsid, but the nature of the ligand can significantly affect its association with virions. PMID: 20631131 [PubMed - as supplied by publisher] | | |
| Effects of Long Term Culture on Human Embryonic Stem Cell Aging.
July 16, 2010 at 8:14 AM
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| | Effects of Long Term Culture on Human Embryonic Stem Cell Aging. Stem Cells Dev. 2010 Jul 14; Authors: Xie X, Hiona A, Lee AS, Cao F, Huang M, Li Z, Cherry A, Pei XT, Wu JC In recent years, human embryonic stem (hES) cells have become a promising cell source for regenerative medicine. Although hES cells have the ability for unlimited self-renewal, potential adverse effects of long-term cell culture upon hES cells must be investigated before therapeutic applications of hES cells can be realized. Here we investigated changes in molecular profiles associated with young (<60 passages) and old (>120 passages) cells of the H9 hES cell line as well as young (<85 passages) and old (>120 passages) cells of the PKU1 hES cell line. Our results show that morphology, stem cell markers, and telomerase activity do not differ significantly between young and old passage cells. Cells from both age groups were also shown to differentiate into derivatives of all three germ layers upon spontaneous differentiation in vitro. Interestingly, mitochondrial dysfunction was found to occur with prolonged culture. Old passage cells of both the H9 and PKU1 lines were characterized by higher mitochondrial membrane potential, larger mitochondrial morphology, and higher reactive oxygen species (ROS) content compared to their younger counterparts. Teratomas derived from higher passage cells were also found to have an uneven preference for differentiation as compared to tumors derived from younger cells. These findings suggest that prolonged culture of hES cells may negatively impact mitochondrial function and possibly affect long-term pluripotency. PMID: 20629482 [PubMed - as supplied by publisher] | | |
| Caloric restriction attenuates the age-associated increase of adipose-derived stem cells but further reduces their proliferative capacity.
July 16, 2010 at 8:14 AM
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| | Caloric restriction attenuates the age-associated increase of adipose-derived stem cells but further reduces their proliferative capacity. Age (Dordr). 2010 Jul 14; Authors: Schmuck EG, Mulligan JD, Saupe KW White adipose tissue is a promising source of mesenchymal stem cells. Currently, little is known about the effect of age and caloric restriction (CR) on adipose-derived stem cells (ASC). This is important for three reasons: firstly, age and CR cause extensive remodeling of WAT; it is currently unknown how this remodeling affects the resident stem cell population. Secondly, stem cell senescence has been theorized as one of the causes of aging and could reduce the utility of a stem cell as a reagent. Thirdly, the mechanism by which CR extends lifespan is currently not known, one theory postulates that CR maintains the resident stem cell population in youthful "fit" state. For the purpose of this study, we define ASC as lineage negative (lin(-))/CD34(+(low))/CD31(-). We show that aging increases the abundance of ASC and the expression of Cdkn2a 9.8-fold and Isl1 60.6-fold. This would suggest that aging causes an accumulation of non-replicative ASC. CR reduced the percentage of ASC in the lin(-) SVF while also reducing colony forming ability. Therefore, CR appears to have anti-proliferative effects on ASC that may be advantageous from the perspective of cancer, but our data raises the possibility that it may be disadvantageous for regenerative medicine applications. PMID: 20628827 [PubMed - as supplied by publisher] | | |
| MicroRNA-34a induces endothelial progenitor cell senescence and impedes its angiogenesis via suppressing silent information regulator 1.
July 16, 2010 at 8:14 AM
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| | MicroRNA-34a induces endothelial progenitor cell senescence and impedes its angiogenesis via suppressing silent information regulator 1. Am J Physiol Endocrinol Metab. 2010 Jul;299(1):E110-6 Authors: Zhao T, Li J, Chen AF Endothelial progenitor cells (EPCs) play an important role in angiogenesis, which is essential for numerous physiological processes as well as tumor growth. Several microRNAs (miRNAs) have been reported to be involved in angiogenesis. MiR-34a, recently reported as a tumor suppressor, has been found to target silent information regulator 1 (Sirt1), leading to cell cycle arrest or apoptosis. However, the role of miR-34a in EPC-mediated angiogenesis was unknown. The present study tested the hypothesis that miR-34a inhibits EPC-mediated angiogenesis by inducing senescence via suppressing Sirt1. Bone marrow-derived EPCs from adult male Sprague-Dawley rats were used. Results of flow cytometry showed that EPCs after 7 days of culture expressed both stem cell markers CD34 and CD133 and endothelial cell markers VEGFR-2 (flk-1) and VE-cadherin. MiR-34a was expressed in normal EPCs, and overexpression of miR-34a via its mimic transfection significantly increased its expression and impaired in vitro EPC angiogenesis. MiR-34a overexpression led to a significantly increased EPC senescence, paralleled with an approximately 40% Sirt1 reduction. Furthermore, knockdown of Sirt1 by its siRNA resulted in diminished EPC angiogenesis and increased senescence. Finally, overexpression of miR-34a increased the level of Sirt1 effector-acetylated forkhead box O transcription factors 1 (FoxO1), an effect mimicked in EPCs following Sirt1 knockdown. In conclusion, miR-34a impairs EPC-mediated angiogenesis by induction of senescence via inhibiting Sirt1. PMID: 20424141 [PubMed - indexed for MEDLINE] | | |
| Differentiation of human bone marrow mesenchymal stem cells into bladder cells: potential for urological tissue engineering.
July 16, 2010 at 8:14 AM
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| | Differentiation of human bone marrow mesenchymal stem cells into bladder cells: potential for urological tissue engineering. Tissue Eng Part A. 2010 May;16(5):1769-79 Authors: Tian H, Bharadwaj S, Liu Y, Ma PX, Atala A, Zhang Y Bone marrow mesenchymal stem cells (BMSCs) are capable of differentiating into multiple cell types, providing an alternative cell source for cell-based therapy and tissue engineering. Simultaneous differentiation of human BMSCs into smooth muscle cells (SMCs) and urothelium would be beneficial for clinical applications in bladder regeneration for patients with bladder exstrophy or cancer who need cystoplasty. We investigated the ability of human BMSCs to differentiate toward both SMCs and urothelium with cocultured or conditioned media and analyzed growth factors from a coculture system. After being cocultured with urothelium or cultured using urothelium-derived conditioned medium, human BMSCs expressed urothelium-specific genes and proteins: uroplakin-Ia, cytokeratin-7, and cytokeratin-13. When cocultured with SMCs or cultured in SMC-conditioned medium, human BMSCs expressed SMC-specific genes and proteins: desmin and myosin. Several growth factors (hepatocyte growth factor, platelet-derived growth factor-homodimer polypeptide of B chain (BB), transforming growth factor-beta1, and vascular endothelial growth factor) were detected in the SMC cocultured media and in the urothelium cocultured media (epidermal growth factor, platelet-derived growth factor-BB, transforming growth factor-beta1, and vascular endothelial growth factor). BMSC-scaffold constructs significantly improved cell contractility after myogenic differentiation. In vivo-grafted cells displayed significant matrix infiltration and expressed SMC-specific markers in the nanofibrous poly-l-lactic acid scaffolds. In conclusion, smooth muscle- and urothelium-like cells derived from human BMSCs provide an alternative cell source for potential use in bladder tissue engineering. PMID: 20020816 [PubMed - indexed for MEDLINE] | | |
| Principles of biomimetic vascular network design applied to a tissue-engineered liver scaffold.
July 16, 2010 at 8:14 AM
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| | Principles of biomimetic vascular network design applied to a tissue-engineered liver scaffold. Tissue Eng Part A. 2010 May;16(5):1469-77 Authors: Hoganson DM, Pryor HI, Spool ID, Burns OH, Gilmore JR, Vacanti JP Branched vascular networks are a central component of scaffold architecture for solid organ tissue engineering. In this work, seven biomimetic principles were established as the major guiding technical design considerations of a branched vascular network for a tissue-engineered scaffold. These biomimetic design principles were applied to a branched radial architecture to develop a liver-specific vascular network. Iterative design changes and computational fluid dynamic analysis were used to optimize the network before mold manufacturing. The vascular network mold was created using a new mold technique that achieves a 1:1 aspect ratio for all channels. In vitro blood flow testing confirmed the physiologic hemodynamics of the network as predicted by computational fluid dynamic analysis. These results indicate that this biomimetic liver vascular network design will provide a foundation for developing complex vascular networks for solid organ tissue engineering that achieve physiologic blood flow. PMID: 20001254 [PubMed - indexed for MEDLINE] | | |
| Tissue engineering of lung: the effect of extracellular matrix on the differentiation of embryonic stem cells to pneumocytes.
July 16, 2010 at 8:14 AM
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| | Tissue engineering of lung: the effect of extracellular matrix on the differentiation of embryonic stem cells to pneumocytes. Tissue Eng Part A. 2010 May;16(5):1515-26 Authors: Lin YM, Zhang A, Rippon HJ, Bismarck A, Bishop AE We have previously differentiated lung epithelium from human and murine embryonic stem cells (mESCs) and are now exploring the potential applications of these cells, including in the engineering of lung tissue constructs. In this study, we hypothesized that the differentiation and maintenance of lung epithelium derived from mESCs can be enhanced by extracellular matrix (ECM) proteins. Our established differentiation protocol was applied to mESCs grown on a range of ECMs: collagen I, laminin 332, fibronectin, Matrigel, and, as an experimental control, gelatin. The ECMs were coated onto tissue culture plastic (TCP) and poly-DL-lactic acid (PDLLA), a biodegradable polymer we have previously shown to support the growth of mature pneumocytes. Matrigel or Laminin-332 coating of either TCP or PDLLA film resulted in enhanced surfactant protein C gene expression in differentiating mESCs, a direct indication of the upregulation of lung epithelial differentiation. For each combination, changes in the contact angle and zeta potential of protein-coated TCP and PDLLA film confirmed protein adsorption. We conclude that the choice of the coating protein can greatly affect the differentiation of ESCs, and laminin-332-coated PDLLA provided an ECM-degradable scaffold combination that is suitable for engineering of lung tissue constructs. PMID: 20001250 [PubMed - indexed for MEDLINE] | | |
| Bolus delivery of mesenchymal stem cells to injured vasculature in the rabbit carotid artery produces a dysfunctional endothelium.
July 16, 2010 at 8:14 AM
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| | Bolus delivery of mesenchymal stem cells to injured vasculature in the rabbit carotid artery produces a dysfunctional endothelium. Tissue Eng Part A. 2010 May;16(5):1657-65 Authors: O'Shea CA, Hynes SO, Shaw G, Coen BA, Hynes AC, McMahon J, Murphy M, Barry F, O'Brien T Endothelial dysfunction is an important factor in cardiovascular pathology. It has been suggested that pluripotent mesenchymal stem cells (MSCs) may contribute to repair of the endothelium through paracrine pathways. Enhanced re-endothelialization may be associated with a better outcome following angioplasty procedures. We examined the effect of the delivery of MSCs to a denuded vessel in vivo. The right carotid arteries of New Zealand white rabbits were denuded using an uninflated 3-French Fogarty balloon catheter. 1 x 10(5) MSCs in a bolus of 150 microL were then delivered intraluminally and allowed to dwell for 20 min. MSC engraftment was assessed using PKH-26 labeling and transduction with adenoviral reporter genes. Vessels were examined at 2 weeks for levels of endothelialization, as well as for neointimal hyperplasia and vasomotor function. Engraftment of MSCs was noted in the vessel wall following local arterial delivery. Endothelialization was improved following bolus MSC delivery at 2 weeks post-intervention. However, this endothelium is manifestly dysfunctional as indicated by a significant impairment in vasomotor activity and a significant increase in neointimal formation post-bolus delivery. Consistent with the formation of a dysfunctional endothelium, there was a higher rate of vessel occlusions in bolus-treated vessels due to not only predominately thrombosis but also neointimal hyperplasia. Our results suggest that naive MSCs delivered as a bolus to the occluded injured vascular segment generate dysfunctional endothelium presenting a risk of vessel occlusion. Such risks are important and need to be further assessed. PMID: 20001215 [PubMed - indexed for MEDLINE] | | |
| Transcoronary Bone Marrow-Derived Progenitor Cells in a Child With Myocardial Infarction: First Pediatric Experience.
July 16, 2010 at 7:29 AM
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| | Transcoronary Bone Marrow-Derived Progenitor Cells in a Child With Myocardial Infarction: First Pediatric Experience. Clin Cardiol. 2010 Jun 15; Authors: Limsuwan A, Pienvichit P, Limpijankit T, Khowsathit P, Hongeng S, Pornkul R, Siripornpitak S, Boonbaichaiyapruk S BACKGROUND: Recent advances in stem cell therapy to restore cardiac function have great promise for patients with congestive heart failure after myocardial infarction in an adult population. OBJECTIVE: We examined the benefits of bone marrow-derived progenitor cells treatment modality for the pediatric patient. METHODS AND RESULTS: We present our first case of transcoronary autologous stem cell transplantation in a 9-year-old girl with refractory congestive heart failure secondary to myocardial infarction 1 year after transcatheter revascularization. The child received daily injections of granulocyte colony-stimulating factor for 3 days prior to the bone marrow aspiration. The bone marrow cells were isolated to constitute CD133 + /CD34 + more than 90% of the total number. Subsequently, the progenitor cell suspension was injected via a transcoronary catheter without any complication. Three months after stem cell therapy, her cardiac function, assessed by both cardiac magnetic resonance and echocardiogram, has been improved with the left ventricular ejection fraction at 47% compared to the baseline of 30%. CONCLUSION: This is the first reported pediatric case of successful transcoronary injection of bone marrow-derived progenitor cells for end-stage heart disease. The procedure is considered safe and feasible for the pediatric population. Copyright (c) 2010 Wiley Periodicals, Inc. PMID: 20632394 [PubMed - as supplied by publisher] | | |
| Lentivirus-mediated knockdown of aggrecanase-1 and -2 promotes chondrocyte-engineered cartilage formation in vitro.
July 16, 2010 at 6:46 AM
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| | Lentivirus-mediated knockdown of aggrecanase-1 and -2 promotes chondrocyte-engineered cartilage formation in vitro. Biotechnol Bioeng. 2010 Jul 14; Authors: Wang ZH, Yang ZQ, He XJ, Kamal BE, Xing Z Chondrocyte-based tissue engineering has emerged as a promising approach for repair of injured cartilage tissues that have a poor self-healing capacity. However, this technique faces a major limitation: dedifferentiation of chondrocytes occurs following several passages in culture. Aggrecan, a major component of cartilage extracellular matrix, plays an essential role in chondrocyte differentiation. The aim of this study is to determine whether inhibition of chondrocyte aggrecanases, key degratative enzymes for aggrecan in cartilage, could benefit chondrocyte differentiation and the preservation of chondrocyte phenotype within a long-term period. Lentivirus-mediated RNA interference (RNAi) was employed to target both aggrecanase-1 and -2 in primary rat chondrocytes, and the transduced cells were seeded into chitosan-gelatin three-dimensional scaffolds. Histological, morphological and biochemical analyses were performed at 1-8 weeks post-implantation to study chondrocyte survival, differentiation, and function. We found that lentivirus-mediated RNAi notably decreased the abundance of aggrecanase transcripts in chondrocytes, but did not affect cell viability. Most importantly, compared to the control constructs seeded with untransduced chondrocytes, the aggrecanase inhibition increased chondrocyte proliferation, and reinforced the production of glycosaminoglycans and total collagen, indicative of chondrocyte differentiation. The mRNA expression of chondrocyte marker genes (collagen II and aggrecan) was enhanced by aggrecanase silencing relative to the control. Together our data demonstrate that inhibition of endogenous aggrecanases facilitates chondrocyte differentiation and chondrocyte-engineered cartilage formation in vitro. The combination of lentiviral delivery system and genetic manipulation techniques provides a useful tool for modulation of chondrocyte phenotype in cartilage engineering. (c) 2010 Wiley Periodicals, Inc. PMID: 20632367 [PubMed - as supplied by publisher] | | |
| [Heart valve and myocardial tissue engineering.]
July 16, 2010 at 6:46 AM
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| | [Heart valve and myocardial tissue engineering.] Herz. 2010 Jul 16; Authors: Cebotari S, Tudorache I, Schilling T, Haverich A Cardiac function, including the heart muscle and valves, can be severely altered by congenital and acquired heart diseases. Several graft materials are currently used to replace diseased cardiac tissue and valvular segments. Implantable grafts are either non-vital or can trigger an immune response which leads to graft calcification and degeneration. None of the existing grafts have the ability to remodel and grow in tandem with the physiological growth of a child and therefore require re-operation. Novel approaches such as tissue engineering have emerged as possible alternatives for cardiac reconstruction. The main concept of tissue engineering includes the use of biological and artificial scaffolds that form the shape of the organ structures for subsequent tissue replacement, which will provide absolute biocompatibility, no thrombogenicity, no teratogenicity, long-term durability and growth.Heart valve tissue engineering represents an important field especially in pediatric patients with valve pathologies. In order to create an autologous valve equivalent myofibroblasts and/or endothelial cells are seeded on specially designed scaffolds. Here we describe the different types of cell sources and different types of matrices currently used in heart valve tissue engineering. Valve manufacture is carried out in specially designed bioreactors providing physiological conditions. The number of clinical studies using tissue engineered valves is still limited; however, several promising results have already demonstrated their durability and ability to grow.Myocardial tissue engineering aims to repair, replace and regenerate damaged cardiac tissue using tissue constructs created ex vivo. Conceivable indications for clinical application of tissue engineered myocardial-implant substitutes include ischemic cardiomyopathies, as well as right ventricular outflow tract reconstruction in patients with congenital heart diseases. Therapeutic application of functional (contractile) tissue engineered heart muscle appears feasible once key issues such as identification of the suitable human cell source, large scale expansion and suitable scaffolds are solved. In addition, the present article discusses the importance of vascularization as an important prerequisite for successful bio-artificial myocardial tissue.Further experimental and clinical research on cardiovascular tissue engineering is felt to be of great importance for others as well as for us in order to create an ideal heart valve/myocardial substitute and help our patients with advanced cardiac pathologies. PMID: 20631970 [PubMed - as supplied by publisher] | | |
| Transforming Growth Factor beta, Bone Morphogenetic Protein, and Vascular Endothelial Growth Factor Mediate Phenotype Maturation and Tissue Remodeling by Embryonic Valve Progenitor Cells: Relevance for Heart Valve Tissue Engineering.
July 16, 2010 at 6:46 AM
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| | Transforming Growth Factor beta, Bone Morphogenetic Protein, and Vascular Endothelial Growth Factor Mediate Phenotype Maturation and Tissue Remodeling by Embryonic Valve Progenitor Cells: Relevance for Heart Valve Tissue Engineering. Tissue Eng Part A. 2010 Jul 14; Authors: Chiu YN, Norris RA, Mahler G, Recknagel A, Butcher JT Despite years of research, limited understanding of heart valve cell and tissue biology remains a key impediment to valvular tissue engineering progress. Heart valves rapidly evolve structural and cellular composition naturally during embryonic development, which suggests that mimicking these signaling events could advance engineered valve tissue research. Many inductive factors participate in the initial endocardial to mesenchymal transformation event necessary to form the prevalvular cushion, but far less is known about the regulation of cushion remodeling into fibrous leaflets and the associated maturation of valvular progenitors into fibroblasts. In this study, we combine in vitro three-dimensional tissue-engineered models of embryonic valvular remodeling with in vivo analysis to determine the roles of three prominent growth factors during avian mitral valvulogenesis. We show that transforming growth factor-beta3 (TGFbeta3), bone morphogenetic protein 2 (BMP2), and vascular endothelial growth factor A (VEGFA) are expressed in spatiotemporally distinct patterns and at significantly different levels within remodeling embryonic valves in vivo. We then establish dose-dependent functional roles for each growth factor in 3D cultured embryonic valve progenitor cells. TGFbeta3 induced cell migration, invasion, and matrix condensation; BMP2 induced invasion. VEGFA inhibited invasion but increased migration. Finally, we determine that TGFbeta3 induced myofibroblastic differentiation in a dose-dependent manner, whereas VEGFA and BMP2 did not. Collectively, these findings frame a naturally derived blueprint for controlling valvulogenic remodeling and phenotype maturation, which can be integrated into clinically needed regenerative strategies for heart valve disease and to accelerate the development of engineered tissue valves. PMID: 20629541 [PubMed - as supplied by publisher] | | |
| Crosslinked urethane doped polyester biphasic scaffolds: Potential for in vivo vascular tissue engineering.
July 16, 2010 at 6:46 AM
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| | Crosslinked urethane doped polyester biphasic scaffolds: Potential for in vivo vascular tissue engineering. J Biomed Mater Res A. 2010 Jul 13; Authors: Dey J, Xu H, Nguyen KT, Yang J In vivo tissue engineering uses the body as a bioreactor for tissue regeneration, thus placing stringent requirements on tissue scaffolds, which should be mechanically robust for immediate implantation without a long in vitro cell culture time. In addition to mechanical strength, vascular grafts fabricated for in vivo tissue engineering approach must have matching mechanical properties to the target tissues to avoid compliance mismatch, which is one of the reasons for graft failure. We recently synthesized a new generation of strong and elastic biodegradable crosslinked urethane-doped polyesters (CUPE) to address the challenge of developing soft, elastic yet strong biodegradable polymers. This study evaluated the tensile strength, burst pressure, and suture retention of CUPE biphasic scaffolds to determine if the scaffolds met the requirements for immediate implantation in an in vivo tissue engineering approach. In addition, we also examined the hemocompatibility and inflammatory potential of CUPE to demonstrate its potential in serving as a blood-contacting vascular graft material. Tensile strength of CUPE biphasic scaffolds (5.02 +/- 0.70 MPa) was greater than native vessels (1.43 +/- 0.60 MPa). CUPE scaffolds exhibited tunable burst pressure ranging from 1500 mmHg to 2600 mmHg, and adequate suture retention values (2.45 +/- 0.23 N). CUPE showed comparable leukocyte activation and whole blood clotting kinetics to poly(L-lactic acid) PLLA. However, CUPE incited a lesser release of inflammatory cytokines and was found to be non hemolytic. Combined with the mechanical properties and previously demonstrated anti-thrombogenic nature, CUPE may serve as a viable graft material for in vivo blood vessel tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20629026 [PubMed - as supplied by publisher] | | |
| Biological performance of biodegradable amino acid-based poly(ester amide)s: Endothelial cell adhesion and inflammation in vitro.
July 16, 2010 at 6:46 AM
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| | Biological performance of biodegradable amino acid-based poly(ester amide)s: Endothelial cell adhesion and inflammation in vitro. J Biomed Mater Res A. 2010 Jul 13; Authors: Horwitz JA, Shum KM, Bodle JC, Deng M, Chu CC, Reinhart-King CA Functionalized amino-acid-based poly(ester-amide)s (PEA) are a new family of synthetic biodegradable polymers consisting of three naturally occurring building blocks (amino acids, diols, and dicarboxylic acids) that have been suggested to be promising biomaterials for therapeutic use. However, little is known about their cytotoxicity, ability to support cell growth, inflammatory properties, or mechanical properties, key aspects to most biomaterials designed for in vivo implantation and tissue engineering applications. In this study, we investigated the ability of two functionalized PEA materials (amino-functionalized and carboxylic acid functionalized) and a neutral PEA control to support endothelial cell viability, proliferation, and adhesion. Additionally, we investigated the inflammatory response elicited by these functionalized PEA materials using a macrophage cell model. Our results indicate that all forms of PEA were noncytotoxic and noninflammatory in vitro. The amino-functionalized PEA bests supports endothelial cell adhesion, growth, and monolayer formation. Mechanical testing indicates that the elastic moduli of these materials are strongly dependent on the charge formulation, but do exhibit linearly elastic behavior at small strains (<10%). Our data suggest that PEA may be a viable biomaterial for use in tissue engineering applications, particularly for use as a vascular graft. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20629024 [PubMed - as supplied by publisher] | | |
| Topological optimization for designing patient-specific large craniofacial segmental bone replacements.
July 16, 2010 at 6:46 AM
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| | Topological optimization for designing patient-specific large craniofacial segmental bone replacements. Proc Natl Acad Sci U S A. 2010 Jul 13; Authors: Sutradhar A, Paulino GH, Miller MJ, Nguyen TH Restoring normal function and appearance after massive facial injuries with bone loss is an important unsolved problem in surgery. An important limitation of the current methods is heuristic ad hoc design of bone replacements by the operating surgeon at the time of surgery. This problem might be addressed by incorporating a computational method known as topological optimization into routine surgical planning. We tested the feasibility of using a multiresolution three-dimensional topological optimization to design replacements for massive midface injuries with bone loss. The final solution to meet functional requirements may be shaped differently than the natural human bone but be optimized for functional needs sufficient to support full restoration using a combination of soft tissue repair and synthetic prosthetics. Topological optimization for designing facial bone tissue replacements might improve current clinical methods and provide essential enabling technology to translate generic bone tissue engineering methods into specific solutions for individual patients. PMID: 20628014 [PubMed - as supplied by publisher] | | |
| Long-Term Stabilization of Polysaccharide Electrospun Fibres by In Situ Cross-linking.
July 16, 2010 at 6:46 AM
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| | Long-Term Stabilization of Polysaccharide Electrospun Fibres by In Situ Cross-linking. J Biomater Sci Polym Ed. 2010 Jul 12; Authors: Shi L, Visage CL, Chew SY Cross-linking of polysaccharide electrospun constructs using currently available techniques results in poor scaffold structural stability. In general, cross-linked substrates lose their nanofibrous architecture within a short time under physiological conditions. In this study, we introduce an in situ cross-linking electrospinning technique to fabricate and stabilize pullulan/dextran fibres. Pullulan/dextran (4:1 weight ratio, 16.7 and 20 wt%) solutions were preloaded with the chemical cross-linker, trisodium trimetaphosphate (STMP), to enable cross-linking during electrospinning. By increasing STMP from 4 to 16 wt%, the average diameter of electrospun fibres increased significantly from 268+/-35 nm to 416+/-74 nm (P<0.05). Additionally, the enhanced cross-linking effectively decreased the swelling extent of the scaffolds. In particular, in the presence of 10 wt% gelatin, a significant decrease in scaffold swelling ratio was observed (208.5+/-31.3% at 4 wt% STMP vs 133.1+/-9.1% at 16 wt% STMP, P<0.05). In vitro stability studies demonstrated the retention of scaffold fibrous morphology and negligible weight loss in all samples after 28 days. Environmental SEM analysis revealed that at least 16 wt% STMP was required in order to retain the nanofibrous structure of the scaffolds under hydrated conditions. Compared with hydrogels of similar chemical content, the nanofibrous architecture of electrospun scaffolds significantly enhanced human dermal fibroblast (HDF) viability at days 3 and 7 (P<0.05). The incorporation of gelatin and the increase in scaffold cross-linking density favoured HDF cell attachment and spreading. In particular, 16 wt% STMP promoted actin stress fibre formation. Taken together, the results support the promise of using STMP in situ cross-linking for long-term stabilization of polysaccharide electrospun fibres and the advantage of polysaccharide nanofibrous constructs for tissue engineering. PMID: 20626930 [PubMed - as supplied by publisher] | | |
| Hierarchically Designed Agarose and Poly(Ethylene Glycol) Interpenetrating Network Hydrogels for Cartilage Tissue Engineering.
July 16, 2010 at 6:46 AM
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| | Hierarchically Designed Agarose and Poly(Ethylene Glycol) Interpenetrating Network Hydrogels for Cartilage Tissue Engineering. Tissue Eng Part C Methods. 2010 Jul 13; Authors: Dekosky BJ, Dormer NH, Ingavle GC, Roatch CH, Lomakin J, Detamore MS, Gehrke SH A new method for encapsulating cells in interpenetrating network (IPN) hydrogels of superior mechanical integrity was developed. In this study, two biocompatible materials-agarose and poly(ethylene glycol) (PEG) diacrylate-were combined to create a new IPN hydrogel with greatly enhanced mechanical performance. Unconfined compression of hydrogel samples revealed that the IPN displayed a fourfold increase in shear modulus relative to a pure PEG-diacrylate network (39.9 vs. 9.9 kPa) and a 4.9-fold increase relative to a pure agarose network (8.2 kPa). PEG and IPN compressive failure strains were found to be 71% +/- 17% and 74% +/- 17%, respectively, while pure agarose gels failed around 15% strain. Similar mechanical property improvements were seen when IPNs-encapsulated chondrocytes, and LIVE/DEAD cell viability assays demonstrated that cells survived the IPN encapsulation process. The majority of IPN-encapsulated chondrocytes remained viable 1 week postencapsulation, and chondrocytes exhibited glycosaminoglycan synthesis comparable to that of agarose-encapsulated chondrocytes at 3 weeks postencapsulation. The introduction of a new method for encapsulating cells in a hydrogel with enhanced mechanical performance is a promising step toward cartilage defect repair. This method can be applied to fabricate a broad variety of cell-based IPNs by varying monomers and polymers in type and concentration and by adding functional groups such as degradable sequences or cell adhesion groups. Further, this technology may be applicable in other cell-based applications where mechanical integrity of cell-containing hydrogels is of great importance. PMID: 20626274 [PubMed - as supplied by publisher] | | |
| Model for estimating the threshold mechanical stability of structural cartilage grafts used in rhinoplasty.
July 16, 2010 at 6:46 AM
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| | Model for estimating the threshold mechanical stability of structural cartilage grafts used in rhinoplasty. Laryngoscope. 2010 Jun;120(6):1089-93 Authors: Zemek A, Garg R, Wong BJ OBJECTIVES/HYPOTHESIS: Characterizing the mechanical properties of structural cartilage grafts used in rhinoplasty is valuable because softer engineered tissues are more time- and cost-efficient to manufacture. The aim of this study is to quantitatively identify the threshold mechanical stability (e.g., Young's modulus) of columellar, L-strut, and alar cartilage replacement grafts. STUDY DESIGN: Descriptive, focus group survey. METHODS: Ten mechanical phantoms of identical size (5 x 20 x 2.3 mm) and varying stiffness (0.360 to 0.85 MPa in 0.05 MPa increments) were made from urethane. A focus group of experienced rhinoplasty surgeons (n = 25, 5 to 30 years in practice) were asked to arrange the phantoms in order of increasing stiffness. Then, they were asked to identify the minimum acceptable stiffness that would still result in favorable surgical outcomes for three clinical applications: columellar, L-strut, and lateral crural replacement grafts. Available surgeons were tested again after 1 week to evaluate intra-rater consistency. RESULTS: For each surgeon, the threshold stiffness for each clinical application differed from the threshold values derived by logistic regression by no more than 0.05 MPa (accuracy to within 10%). Specific thresholds were 0.56, 0.59, and 0.49 MPa for columellar, L-strut, and alar grafts, respectively. For comparison, human nasal septal cartilage is approximately 0.8 MPa. CONCLUSIONS: There was little inter- and intra-rater variation of the identified threshold values for adequate graft stiffness. The identified threshold values will be useful for the design of tissue-engineered or semisynthetic cartilage grafts for use in structural nasal surgery. PMID: 20513022 [PubMed - indexed for MEDLINE] | | |
| Development of an inductively coupled MR coil system for imaging and spectroscopic analysis of an implantable bioartificial construct at 11.1 T.
July 16, 2010 at 6:46 AM
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| | Development of an inductively coupled MR coil system for imaging and spectroscopic analysis of an implantable bioartificial construct at 11.1 T. Magn Reson Med. 2010 Apr;63(4):998-1006 Authors: Volland NA, Mareci TH, Constantinidis I, Simpson NE Developing a method to noninvasively monitor tissue-engineered constructs is critical for the optimization of construct design and for assessing therapeutic efficacy. For this purpose, NMR is a powerful technique that can be used to obtain both images and spectroscopic data. But the inherent sensitivity of NMR limits the observation of a bioartificial construct with current NMR surface coil technology. In this study, we address this limitation through the development of an inductively coupled, implantable coil system, demonstrate its use at high field (11.1 T), and investigate the use of this coil system for monitoring a bioartificial construct in vitro and in vivo. The results establish that large gains in signal to noise can be obtained with this coil system over that obtainable with a surface coil. This coil system provides a means to quantitatively analyze the structure and function of implanted bioartificial organs. PMID: 20373400 [PubMed - indexed for MEDLINE] | | |
| A novel single-step self-assembly approach for the fabrication of tissue-engineered vascular constructs.
July 16, 2010 at 6:46 AM
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| | A novel single-step self-assembly approach for the fabrication of tissue-engineered vascular constructs. Tissue Eng Part A. 2010 May;16(5):1737-47 Authors: Gauvin R, Ahsan T, Larouche D, Lévesque P, Dubé J, Auger FA, Nerem RM, Germain L There is a clinical need for a functional tissue-engineered blood vessel because small-caliber arterial graft (<5 mm) applications are limited by the availability of suitable autologous vessels and suboptimal performances of synthetic grafts. This study presents an analysis of the mechanical properties of tissue-engineered vascular constructs produced using a novel single-step self-assembly approach. Briefly, the tissue-engineered vascular media were produced by culturing smooth muscle cell in the presence of sodium l-ascorbate until the formation of a cohesive tissue sheet. This sheet was then rolled around a tubular support to create a media construct. Alternatively, the tissue-engineered vascular adventitia was produced by rolling a tissue sheet obtained from dermal fibroblasts or saphenous vein fibroblasts. The standard self-assembly approach to obtain the two-layer tissue-engineered vascular constructs comprising both media and adventitia constructs consists of two steps in which tissue-engineered vascular media were first rolled on a tubular support and a tissue-engineered vascular adventitia was then rolled on top of the first layer. This study reports an original alternative method for assembling tissue-engineered vascular constructs comprising both media and an adventitia in a single step by rolling a continuous tissue sheet containing both cell types contiguously. This tissue sheet was produced by growing smooth muscle cells alongside fibroblasts (saphenous vein fibroblasts or dermal fibroblasts) in the same culture dish separated by a spacer, which is removed later in the culture period. The mechanical strength assessed by uniaxial tensile testing, burst pressure measurements, and viscoelastic behavior evaluated by stepwise stress relaxation tests reveals that the new single-step fabrication method significantly improves the mechanical properties of tissue-engineered vascular construct for both ultimate tensile strength and all the viscoelastic moduli. PMID: 20038201 [PubMed - indexed for MEDLINE] | | |
| Inkjet-based biopatterning of bone morphogenetic protein-2 to spatially control calvarial bone formation.
July 16, 2010 at 6:46 AM
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| | Inkjet-based biopatterning of bone morphogenetic protein-2 to spatially control calvarial bone formation. Tissue Eng Part A. 2010 May;16(5):1749-59 Authors: Cooper GM, Miller ED, Decesare GE, Usas A, Lensie EL, Bykowski MR, Huard J, Weiss LE, Losee JE, Campbell PG The purpose of this study was to demonstrate spatial control of osteoblast differentiation in vitro and bone formation in vivo using inkjet bioprinting technology and to create three-dimensional persistent bio-ink patterns of bone morphogenetic protein-2 (BMP-2) and its modifiers immobilized within microporous scaffolds. Semicircular patterns of BMP-2 were printed within circular DermaMatrix human allograft scaffold constructs. The contralateral halves of the constructs were unprinted or printed with BMP-2 modifiers, including the BMP-2 inhibitor, noggin. Printed bio-ink pattern retention was validated using fluorescent or (125)I-labeled bio-inks. Mouse C2C12 progenitor cells cultured on patterned constructs differentiated in a dose-dependent fashion toward an osteoblastic fate in register to BMP-2 patterns. The fidelity of spatial restriction of osteoblastic differentiation at the boundary between neighboring BMP-2 and noggin patterns improved in comparison with patterns without noggin. Acellular DermaMatrix constructs similarly patterned with BMP-2 and noggin were then implanted into a mouse calvarial defect model. Patterns of bone formation in vivo were comparable with patterned responses of osteoblastic differentiation in vitro. These results demonstrate that three-dimensional biopatterning of a growth factor and growth factor modifier within a construct can direct cell differentiation in vitro and tissue formation in vivo in register to printed patterns. PMID: 20028232 [PubMed - indexed for MEDLINE] | | |
| Development and preclinical evaluation of acellular collagen scaffolding and autologous artificial connective tissue in the regeneration of oral mucosa wounds.
July 16, 2010 at 6:46 AM
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| | Development and preclinical evaluation of acellular collagen scaffolding and autologous artificial connective tissue in the regeneration of oral mucosa wounds. Tissue Eng Part A. 2010 May;16(5):1667-79 Authors: Espinosa L, Sosnik A, Fontanilla MR This work assessed wound healing response in rabbit oral lesions grafted with autologous artificial connective tissue or acellular collagen scaffolds. Autologous artificial oral connective tissue (AACT) was produced using rabbit fibroblasts and collagen I scaffolds. Before implantation, AACT grafts were assayed to demonstrate the presence of fibroblasts and extracellular matrix components, as well as the expression of characteristic genes and secretion of chemokines, cytokines, and growth factors. AACT grafts were tested in the rabbits from which the fibroblasts were obtained, whereas acellular collagen type I scaffolds (CS) were evaluated in a separate group of rabbits. In both cases, contralateral wounds closed by secondary intention were used as controls. In a separate experiment, AACT-grafted wounds were directly compared with contralateral CS-grafted wounds in the same animals. Wound contraction and histological parameters were examined to evaluate closure differences between the treatments in the three animal experiments performed. Contraction of wounds grafted with AACT and CS was significantly lower than in their controls (p < 0.05). Additionally, AACT significantly lowered wound contraction when compared with CS (p < 0.05). Intriguingly, it was observed that AACT-grafted wounds initially displayed a significantly higher (p < 0.05)-albeit transient-inflammatory response than seen in CS-grafted wounds and secondary healed wounds. This suggests that an early inflammatory component may contribute to tissue regeneration. Altogether, the results suggest that AACT- and CS-grafted wounds favor regeneration of oral mucosa. PMID: 20001832 [PubMed - indexed for MEDLINE] | | |
| The inductive effect of bone morphogenetic protein-4 on chondral-lineage differentiation and in situ cartilage repair.
July 16, 2010 at 6:46 AM
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| | The inductive effect of bone morphogenetic protein-4 on chondral-lineage differentiation and in situ cartilage repair. Tissue Eng Part A. 2010 May;16(5):1621-32 Authors: Jiang Y, Chen LK, Zhu DC, Zhang GR, Guo C, Qi YY, Ouyang HW OBJECTIVES: As recent studies have suggested that bone morphogenetic protein-4 (BMP-4) and BMP-7 are promising cartilage differentiation factors, this study aimed to compare the efficacy of BMP-4 and BMP-7 for chondral-lineage differentiation in vitro as well as the efficacy of BMP-4 for articular cartilage repair in vivo. METHODS: Rabbit mesenchymal stromal cells and articular chondrocytes were treated with 10 ng/mL human recombinant BMP-4 or BMP-7. The expression of cartilage-specific genes (col II, aggrecan, and Sox9) and fibroblast growth factor receptor genes was tested by real-time polymerase chain reaction in vitro. Also, full-thickness cartilage defects (diameter 4 mm, thickness 3 mm) were created in New Zealand white rabbits and untreated (group I), or treated with a bilayer collagen scaffold (group II) or BMP-4 with scaffold (group III) (n = 12/group). The repaired tissues were harvested for histology and mechanical testing after 6 or 12 weeks. RESULTS: Cartilage differentiation of mesenchymal stromal cells was more apparent after BMP-4 treatment, as evidenced by higher expression of type II collagen and aggrecan genes. Also, BMP-4 induced higher aggrecan and fibroblast growth factor receptor-2 gene expression in chondrocytes, whereas BMP-7 had no effect. In the in vivo experiments, group III treated with BMP-4 protein had the largest amounts of cartilage tissue, which restored a greater surface area of the defect and achieved higher International Cartilage Repair Society scores. Moreover, Young's modulus, which indicates the mechanical properties of the repaired tissue, was markedly higher in group III than in groups I and II (p < 0.05), but lower than in normal tissue. CONCLUSION: BMP-4 is more potent than BMP-7 for cartilage differentiation. The delivery of BMP-4 protein in a bilayer collagen scaffold stimulates the formation of cartilage tissue. PMID: 20001220 [PubMed - indexed for MEDLINE] | | |
| Formation of proteoglycan and collagen-rich scaffold-free stiff cartilaginous tissue using two-step culture methods with combinations of growth factors.
July 16, 2010 at 6:46 AM
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| | Formation of proteoglycan and collagen-rich scaffold-free stiff cartilaginous tissue using two-step culture methods with combinations of growth factors. Tissue Eng Part A. 2010 May;16(5):1575-84 Authors: Miyazaki T, Miyauchi S, Matsuzaka S, Yamagishi C, Kobayashi K Tissue-engineered cartilage may be expected to serve as an alternative to autologous chondrocyte transplantation treatment. Several methods for producing cartilaginous tissue have been reported. In this study, we describe the production of scaffold-free stiff cartilaginous tissue of pig and human, using allogeneic serum and growth factors. The tissue was formed in a mold using chondrocytes recovered from alginate bead culture and maintained in a medium with transforming growth factor-beta and several other additives. In the case of porcine tissue, the tear strength of the tissue and the contents of proteoglycan (PG) and collagen per unit of DNA increased dose-dependently with transforming growth factor-beta. The length of culture was significantly and positively correlated with thickness, tear strength, and PG and collagen contents. Tear strength showed positive high correlations with both PG and collagen contents. A positive correlation was also seen between PG content and collagen content. Similar results were obtained with human cartilaginous tissue formed from chondrocytes expanded in monolayer culture. Further, an in vivo pilot study using pig articular cartilage defect model demonstrated that the cartilaginous tissue was well integrated with surrounding tissue at 13 weeks after the implantation. In conclusion, we successfully produced implantable scaffold-free stiff cartilaginous tissue, which characterized high PG and collagen contents. PMID: 19938962 [PubMed - indexed for MEDLINE] | | |
| Prosthodontic rehabilitation of hypophosphatasia using dental implants: a review of the literature and two case reports.
July 16, 2010 at 6:46 AM
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| | Prosthodontic rehabilitation of hypophosphatasia using dental implants: a review of the literature and two case reports. J Oral Rehabil. 2009 Jun;36(6):462-8 Authors: Lynch CD, Ziada HM, Buckley LA, O'Sullivan VR, Aherne T, Aherne S There are reports in the literature of the various dental features of hypophosphatasia, especially where it affects the deciduous dentition. The descriptions include both the manifestations of the disorder and the subsequent patterns of tooth loss. There are fewer descriptions of the effects of hypophosphatasia on the permanent dentition and little information on the subsequent prosthodontic management of these patients, particularly in relation to the use of dental implants. The aim of this paper was to review the literature on the dental effects of hypophosphatasia, present two cases and describe how one of those patients, a young adult, was successfully rehabilitated using dental implants. That latter patient's pattern of tooth loss as well as some histological and scanning electron microscopic findings of root cementum from the other case is also described. PMID: 19422434 [PubMed - indexed for MEDLINE] | | |
| Research Highlights
July 15, 2010 at 11:29 AM
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| Regenerative Medicine , July 2010, Vol. 5, No. 4, Pages 501-503.
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