| CIRM Proposes $40 Million Stem Cell "Tools" Round; Board Meeting Accessible in LA
January 30, 2010 at 10:18 AM
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| | For those of you in Southern California who would like to participate in next week's CIRM board meeting, you will be able to do so via a teleconference call from the offices of the Sherry Lansing Foundation in Los Angeles.Additional background information on matters to be acted on at the meeting that begins Tuesday was posted on the CIRM Web site late yesterday and early today. Still not | | |
| Isolation of pig bone marrow mesenchymal stem cells suitable for one-step procedures in chondrogenic regeneration.
January 30, 2010 at 6:56 AM
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| | Isolation of pig bone marrow mesenchymal stem cells suitable for one-step procedures in chondrogenic regeneration. J Tissue Eng Regen Med. 2010 Jan 28; Authors: Peterbauer-Scherb A, van Griensven M, Meinl A, Gabriel C, Redl H, Wolbank S Large animals such as pigs are good models for skeletal tissue engineering, since they provide physical forces similar to those of humans. Porcine bone marrow mesenchymal stem cells (BMSCs) have shown regenerative capacity similar to those of human BMSCs and can therefore be preclinically applied in settings corresponding to autologous transplantation in patients. Aiming at a one-step procedure for cartilage regeneration with autologous BMSCs, three straightforward isolation methods for BMSCs of Göttingen minipigs were compared. For this purpose, the BMSC fraction was enriched by red blood cell (RBC) lysis, dextran sedimentation or density gradient centrifugation. Isolated BMSCs were evaluated with regard to cell yield, proliferation capacity, phenotype and ability to differentiate to the chondrogenic lineage. Highest cell yields determined at the time of subcultivation were obtained using RBC lysis. In comparison, dextran sedimentation was less efficient but sup! erior to density gradient centrifugation, which yielded significantly lower cell numbers than RBC lysis. The evaluated isolation methods resulted in cultures with equal proliferative capacity, with constant population doubling times of 50-55 h for at least 100 days (approximating to 40 cumulative population doublings) in vitro. Chondrogenic differentiation in micromass pellet cultures was evaluated by glycosaminoglycan quantification, histological staining with Alcian blue and safranin O and immunohistochemical analysis for collagen type II. These evaluations demonstrated that all three isolation methods yielded cells capable of generating cartilaginous tissue in vitro. According to our data, RBC lysis can be used to efficiently isolate porcine BMSCs in a short time frame which would allow for intraoperative one-step procedures in preclinical cartilage regeneration studies. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20112279 [PubMed - as supplied by publisher] | | |
| Human progenitor-derived endothelial cells vs. venous endothelial cells for vascular tissue engineering: an in vitro study.
January 30, 2010 at 6:56 AM
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| | Human progenitor-derived endothelial cells vs. venous endothelial cells for vascular tissue engineering: an in vitro study. J Tissue Eng Regen Med. 2010 Jan 28; Authors: Thebaud NB, Bareille R, Remy M, Bourget C, Daculsi R, Bordenave L The isolation of endothelial progenitor cells from human peripheral blood generates a great hope in vascular tissue engineering because of particular benefit when compared with mature endothelial cells. We explored the capability of progenitor-derived endothelial cells (PDECs) to line fibrin and collagen scaffolds in comparison with human saphenous and umbilical cord vein endothelial cells (HSVECs and HUVECs): (a) in a static situation, allowing definition of the optimal cell culture conditions with different media and cell-seeding densities to check cell behaviour; (b) under shear stress conditions (flow chambers or tubular vascular constructs), allowing investigation of cell response and mRNA expression on both substrates by oligonucleotide microarray analysis and quantitative real-time PCR. Well characterized PDECs: (a) could not be expanded adequately with the usual mature ECs culture media; (b) were able to colonize and grow on fibrin glue; (c) exhibited high! er resistance to oxidative stress than HSVECs and HUVECs; (d) withstood physiological shear stress when lining both substrates in flow chambers, and their gene expression was regulated; (e) colonized a collagen-impregnated vascular prosthesis and were able to sense mechanical forces. Our results provide an improved qualification of PDECs for vascular tissue engineering. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20112278 [PubMed - as supplied by publisher] | | |
| Surface modification of a biodegradable composite by UV laser ablation: in vitro biological performance.
January 30, 2010 at 6:56 AM
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| | Surface modification of a biodegradable composite by UV laser ablation: in vitro biological performance. J Tissue Eng Regen Med. 2010 Jan 28; Authors: Martins A, Gang W, Pinho ED, Rebollar E, Chiussi S, Reis RL, León B, Neves NM Melt blends of chitosan and biodegradable aliphatic polyester have been physically and biologically studied, presenting great potential for biomedical applications. Structurally, poly(butylene succinate)-chitosan (PBS/Cht) composite scaffolds are covered by a thin PBS layer, preventing the desired interaction of cells/tissues with the chitosan particules. In the present work, a selective and controlled ablation of this skin layer was induced by UV laser processing. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) data demonstrated an increment of chitosan components and others resulting from the laser ablation process. The biological activity (i.e. cell viability and proliferation) on the inner regions of the composite scaffolds is not significantly different from those of the external layer, despite the observed differences in surface roughness (determined by interferometric optical profilometry) and wettability! (water contact angle). However, the morphology of human osteoblastic cells was found to be considerably different in the case of laser-processed samples, since the cells tend to aggregate in multilayer columnar structures, preferring the PBS surface and avoiding the chitosan-rich areas. Thus, UV laser ablation can be considered a model technique for the physical surface modification of biomaterials without detrimental effects on cellular activity. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20112276 [PubMed - as supplied by publisher] | | |
| Fine-tuning scaffolds for tissue regeneration: effects of formic acid processing on tissue reaction to silk fibroin.
January 30, 2010 at 6:56 AM
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| | Fine-tuning scaffolds for tissue regeneration: effects of formic acid processing on tissue reaction to silk fibroin. J Tissue Eng Regen Med. 2010 Jan 28; Authors: Ghanaati S, Orth C, Unger RE, Barbeck M, Webber MJ, Motta A, Migliaresi C, James Kirkpatrick C Formic acid (FA) plays a key role in the preparation of silk fibroin (SF) scaffolds from cocoons of Bombyx mori and is used for fibre distribution. In this study, we used a subcutaneous implantation model in Wistar rats to examine SF scaffolds prepared by treating the degummed cocoon with FA for either 30 or 60 min. The tissue reaction and inflammatory response to SF was assessed by qualitative histology at intervals from 3 to 180 days. Additionally, dynamic biomaterial-induced vascularization and biomaterial degradation were quantified using a technique for analysing an image of the entire implanted biomaterial. Varying the FA treatment time led to different scaffold morphologies and resulted in two distinct peri-implant tissue reactions. The 30 min-treated scaffold was integrated into the surrounding tissue beginning at day 3 after implantation and vascularization increased 10-fold from 15 to 180 days, while the scaffold was continuously degraded throughout the ! first 90 days. In contrast, the 60 min-treated SF scaffold appeared as bulk for the first 90 days after implantation, after which a rapid degradation and vascularization process began. After 180 days, the tissue response was similar for both scaffolds, with eventual formation of a well vascularized connective tissue integrating the SF fibres. This study indicates that by modifying the FA treatment time, the tissue reaction to SF scaffolds can be tailored for different tissue-engineering applications. The tunability and biocompatibility of SF make it an attractive scaffold for exploration in regenerative medicine and clinical tissue engineering. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20112273 [PubMed - as supplied by publisher] | | |
| Aligned Bioactive Multi-Component Nanofibrous Nanocomposite Scaffolds for Bone Tissue Engineering.
January 30, 2010 at 6:56 AM
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| | Aligned Bioactive Multi-Component Nanofibrous Nanocomposite Scaffolds for Bone Tissue Engineering. Macromol Biosci. 2010 Jan 28; Authors: Jose MV, Thomas V, Xu Y, Bellis S, Nyairo E, Dean D The ability to mimic the chemical, physical and mechanical properties of the natural extra-cellular matrix is a key requirement for tissue engineering scaffolds to be successful. In this study, we successfully fabricated aligned nanofibrous multi-component scaffolds for bone tissue engineering using electrospinning. The chemical features were mimicked by using the natural components of bone: collagen and nano-hydroxyapatite along with poly[(D,L-lactide)-co-glycolide] as the major component. Anisotropic features were mimicked by aligning the nanofibers using a rotating mandrel collector. We evaluated the effect of incorporation of nano-HA particles to the system. The morphology and mechanical properties revealed that,at low concentrations, nano-HA acted as a reinforcement. However, at higher nano-HA loadings, it was difficult to disrupt aggregations and, hence, a detrimental effect was observed on the overall scaffold properties. Thermal analysis showed that there ! were slight interactions between the individual components even though the polymers existed as a two-phase system. Preliminary in vitro cell-culture studies revealed that the scaffold supported cell adhesion and spreading. The cells assumed a highly aligned morphology along the direction of fiber orientation. Protein adsorption experiments revealed that the synergistic effect of increased surface area and the presence of nano-HA in the polymer matrix enhanced total protein adsorption. Crosslinking with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride resulted in improved mechanical properties of the scaffolds and improved degradation stability, under physiological conditions. PMID: 20112236 [PubMed - as supplied by publisher] | | |
| [Educational initiative of the German Society of Urology for innovative research : Workshops 2009.]
January 30, 2010 at 6:56 AM
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| | [Educational initiative of the German Society of Urology for innovative research : Workshops 2009.] Urologe A. 2010 Jan;49(1):91-4 Authors: Sievert KD, Unteregger G, Nawroth R, Junker K, Becker C, Wullich B, The tasks of the Working Group on Urological Research (AuF) of the German Society of Urology (DGU) are to support communication and initiation of joint ventures in German urology and to cooperate with associated subjects and neighboring countries. The annual "wet lab workshops" needs a space between annual and "wet lab workshops" on the topics of tumor cell culture, gene silencing, proteomics, and tissue engineering and the use instead of annual topic-related symposium"urological research," organized and carried out by the AuF as of 2009, serve to achieve a close change to closer integration of praxis and theory. This should contribute to a lasting quality improvement of the scientific work in urology. Accomplishing these objectives seems urgently necessary to preserve the interests of urologists, because more than ever research has become indispensable in an increasingly difficult environment of health care policy. PMID: 20111922 [PubMed - in process] | | |
| Regulation of Gene Expression by PI3K in Mouse Growth Plate Chondrocytes.
January 30, 2010 at 6:56 AM
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| | Regulation of Gene Expression by PI3K in Mouse Growth Plate Chondrocytes. PLoS One. 2010;5(1):e8866 Authors: Ulici V, James CG, Hoenselaar KD, Beier F BACKGROUND: Endochondral ossification, the process through which long bones are formed, involves chondrocyte proliferation and hypertrophic differentiation in the cartilage growth plate. In a previous publication we showed that pharmacological inhibition of the PI3K signaling pathway results in reduced endochondral bone growth, and in particular, shortening of the hypertrophic zone in a tibia organ culture system. In this current study we aimed to investigate targets of the PI3K signaling pathway in hypertrophic chondrocytes. METHODOLOGY/PRINCIPAL FINDINGS: Through the intersection of two different microarray analyses methods (classical single gene analysis and GSEA) and two different chondrocyte differentiation systems (primary chondrocytes treated with a pharmacological inhibitor of PI3K and microdissected growth plates), we were able to identify a high number of genes grouped in GSEA functional categories regulated by the PI3K signaling pathway. Genes such as P! hlda2 and F13a1 were down-regulated upon PI3K inhibition and showed increased expression in the hypertrophic zone compared to the proliferative/resting zone of the growth plate. In contrast, other genes including Nr4a1 and Adamts5 were up-regulated upon PI3K inhibition and showed reduced expression in the hypertrophic zone. Regulation of these genes by PI3K signaling was confirmed by quantitative RT-PCR. We focused on F13a1 as an interesting target because of its known role in chondrocyte hypertrophy and osteoarthritis. Mouse E15.5 tibiae cultured with LY294002 (PI3K inhibitor) for 6 days showed decreased expression of factor XIIIa in the hypertrophic zone compared to control cultures. CONCLUSIONS/SIGNIFICANCE: Discovering targets of signaling pathways in hypertrophic chondrocytes could lead to targeted therapy in osteoarthritis and a better understanding of the cartilage environment for tissue engineering. PMID: 20111593 [PubMed - in process] | | |
| Wound Stimulation by Growth-Arrested Human Keratinocytes and Fibroblasts: HP802-247, a New-Generation Allogeneic Tissue Engineering Product.
January 30, 2010 at 6:56 AM
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| | Wound Stimulation by Growth-Arrested Human Keratinocytes and Fibroblasts: HP802-247, a New-Generation Allogeneic Tissue Engineering Product. Dermatology. 2010 Jan 26; Authors: Goedkoop R, Juliet R, You PH, Daroczy J, de Roos KP, Lijnen R, Rolland E, Hunziker T Background: HP802-247 is a new-generation, allogeneic tissue engineering product consisting of growth-arrested, human keratinocytes (K) and fibroblasts (F) delivered in a fibrin matrix by a spray device. Objective: To identify the preferred dose of HP802-247 based on cell concentration and K/F ratio. Methods: A multicenter, randomized, double-blind, placebo-controlled, explorative phase II study of 6 different doses of HP802-247 administered once per week for 12 consecutive weeks in chronic venous leg ulcers. Results: HP802-247 was safe and well tolerated and showed increasing efficacy dependent on cell concentration and K/F ratio, in line with in vitro growth factor release data. The mean complete closure rate at week 12 for all patients treated with HP802-247 was 40%, and for placebo it was 33%. In contrast to placebo, all HP802-247 dose groups improved from week 12 to 24. Conclusion: As an integral part of a rational tissue engineering product development, this! explorative trial identified the preferred dose of HP802-247 for further clinical studies. PMID: 20110630 [PubMed - as supplied by publisher] | | |
| Dual delivery of VEGF and MCP-1 to support endothelial cell transplantation for therapeutic vascularization.
January 30, 2010 at 6:56 AM
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| | Dual delivery of VEGF and MCP-1 to support endothelial cell transplantation for therapeutic vascularization. Biomaterials. 2010 Jan 26; Authors: Jay SM, Shepherd BR, Andrejecsk JW, Kyriakides TR, Pober JS, Saltzman WM Transplantation of endothelial cells (EC) for therapeutic vascularization is a promising approach in tissue engineering but has yet to be proven effective in clinical trials. This cell-based therapy is hindered by significant apoptosis of EC upon transplantation as well as poor recruitment of host mural cells to stabilize nascent vessels. Here, we address these deficiencies by augmenting endothelial cell transplantation with dual delivery of vascular endothelial growth factor (VEGF) - to improve survival of transplanted EC - and monocyte chemotactic protein-1 (MCP-1) - to induce mural cell recruitment. We produced alginate microparticles that deliver VEGF and MCP-1 with distinct release kinetics and that can be integrated into a collagen/fibronectin (protein) gel construct for delivery of EC. Combined delivery of VEGF and MCP-1 increased functional vessel formation from transplanted EC and also led to a higher number of smooth muscle cell-invested vessels than did! EC therapy alone. Despite the well-known role of MCP-1 in inflammation, these beneficial effects were accomplished without a long-term increase in monocyte/macrophage recruitment or a shift to a pro-inflammatory (M1) macrophage phenotype. Overall, these data suggest a potential benefit of combined delivery of MCP-1 and VEGF from EC-containing hydrogels as a strategy for therapeutic vascularization. PMID: 20110124 [PubMed - as supplied by publisher] | | |
| Biocompatibility of a synthetic extracellular matrix on immortalized vocal fold fibroblasts in 3d culture.
January 30, 2010 at 6:56 AM
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| | Biocompatibility of a synthetic extracellular matrix on immortalized vocal fold fibroblasts in 3d culture. Acta Biomater. 2010 Jan 25; Authors: Chen X, Thibeault SL In order to promote wound repair and induce tissue regeneration, an engineered hyaluronan (HA) hydrogel - Carbylan GSX, which contains di(thiopropionyl) bishydrazide-modified hyaluronic acid (HA-DTPH), di(thiopropionyl) bishydrazide-modified gelatin (Gtn-DTPH) and polyethylene glycol diacrylate (PEGDA), has been developed for extracellular matrix (ECM) defects of the superficial and middle layers of the lamina propria. The purpose of this study was to evaluate the biocompatibility of Carbylan GSX in a previously established immortalized human vocal fold fibroblast (hVFF) cell line prior to human clinical trials. Immortalized hVFF proliferation, viability, apoptosis and transcript analysis for both ECM constituents and inflammatory markers were measured for two-dimensional and three-dimensional culture conditions. There were no significant differences in morphology, cell marker protein expression, proliferation, viability and apoptosis of hVFF cultured with Carbyla! n GSX compared to Matrigel, a commercial 3D control, after one week. Gene expression levels for fibromodulin, TGF-beta1, and TNF-alpha were similar between Carbylan GSX and Matrigel. Fibronectin, hyaluronidase 1 and COX2 expression levels were induced by Carbylan GSX; whereas IL6, IL8. COL1 and hyaluronic acid synthase 3 expression levels were decreased by Carbylan GSX. This investigation demonstrates that Carbylan GSX may serve as a natural biomaterial for tissue engineering of human vocal folds. PMID: 20109588 [PubMed - as supplied by publisher] | | |
| Tissue engineering technologies: just a quick note about transplantation of bioengineered donor trachea and augmentation cystoplasty by de novo engineered bladder tissue.
January 30, 2010 at 6:56 AM
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| | Tissue engineering technologies: just a quick note about transplantation of bioengineered donor trachea and augmentation cystoplasty by de novo engineered bladder tissue. G Chir. 2009 Nov-Dec;30(11-12):514-9 Authors: Alberti C English version Summary: Tissue engineering technologies: just a quick note about transplantation of bioengineered donor trachea and augmentation cystoplasty by de novo engineered bladder tissue. C. Alberti Tissue engineering is a multidisciplinary scientific field that aims at manufacturing in vitro biological substitutes to enhance or replace failing human organs. Various types of biodegradable synthetic polymer (polyglycolic acid, PGA; polylactic acid, PLA; polylactic-coglycolic acid), naturally-derived (alginate, collagen), acellular tissue-made up (small intestinal submucosa, SIS; acellular bladder submucosa, ABS) and composite (PGA bound to collagen) materials have been used as scaffold for either "unseeded" (cell-free) or "seeded" (autologous cells seeded onto the matrix) tissue engineering strategies. The unseeded technique is directed at promoting the in vivo tissue regenerative process, unfortunately with certain limitations, whereas ! the "seeded technique" aims at creating in vitro functional replacement tissues or organs. Recently, a decellularized human dead donor trachea has been used as scaffold, that was then seeded, in vitro, by recipient epithelial cells and mesenchymal stem cell-derived chondrocytes, to obtain a bioengineered airway to replace recipient's failing left main bronchus. As far as clinical applications in Urology are concerned, a cell-based approach (PGA-collagen composite scaffold seeded with autologous cells) has been achieved to successfully carry-out an augmentation cystoplasty in subjects with end-stage neuropathic high pressure/poorly compliant bladder. The use of autologous cells, wherein a specimen of tissue is harvested by biopsy from the host, avoids the risk of rejection. Nevertheless, the use of adult organ-specific cells shows many limitations, such as difficulties in their harvesting (potential complications associated with invasive biopsies) and their low! proliferative ability. Therefore, various populations of eith! er embry onic or adult stem cells and progenitor cells have been studied as useful cell sources for the tissue engineering. Bioreactors are essential in such technologies, both providing chemo-physical cell culture dynamic conditions, that mimic the in vivo environment, and allowing the assessment of responses of biological substitutes to different biochemical signals and mechanical forces. Versione italiana Riassunto: Tecnologie di ingegneria tessutale: breve nota su trapianto di trachea da donatore bioingegnerizzata e cistoplastica di ampliamento mediante tessuto vescicale ingegnerizzato de novo. C. Alberti Per ingegneria dei tessuti si intende un settore scientifico multidisciplinare volto alla realizzazione in vitro di strutture biologiche di ricambio, atte a rinforzare o sostituire organi umani in precarie condizioni. Diversi tipi di materiali - quali polimeri sintetici biodegradabili (acido poliglicolico, PGA; acido polilattico, PLA; copolimero PGA-PLA), sostanze di derivazione! naturale (alginato, collagene), matrici acellulari (submucosa del piccolo intestino, SIS; submucosa acellulare vescicale, ABS), o tra loro assemblati (PGL legato a collagene) - sono stati impiegati come intelaiature (scaffold) sia prive di cellule ("unseeded technique"), allo scopo di promuovere, in vivo, nell'organo in cui vengono impiantate, naturali processi rigenerativi, non sempre, però, attuantisi, sia per sviluppare, in vitro, previa semina, nella loro compagine, di cellule del potenziale ricevente (autologous cell seeded technique), un tessuto ingegnerizzato, idoneo all'impiego in chirurgia ricostruttiva. Recentemente, la trachea di donatore morto, opportunamente decellularizzata, è stata usata quale scaffold per essere seminata, in vitro, con cellule epiteliali e condrociti derivati da cellule staminali mesenchimali del ricevente, al fine di ottenere un segmento ingegnerizzato di via respiratoria tale da sostituire il grosso bronco sinistro, gr! avemente malacico, del ricevente. In riferimento alle applicaz! ioni in ambito urologico, è stato coronato da successo l'impiego di una "seeded technique" (cellule autologhe seminate su scaffold composto di PGA legato a collagene) per confezionare tessuto ingegnerizzato vescicale usato nella realizzazione di cistoplastica d'ampliamento in soggetti affetti da "vescica neurologica", ormai in fase estremamente grave (livelli alti di pressione endovescicale, compliance vescicale molto ridotta). L'impiego di cellule autologhe, ottenute, mediante biopsia, dai tessuti del ricevente, evita il rischio di rigetto dopo l'impianto. Peraltro, il ricorso a cellule organo-specifiche "adulte" presenta dei limiti correlati alla loro raccolta (potenziali complicazioni associate all'invasività della biopsia) ed alle difficoltà di cultura in vitro data la loro bassa capacità proliferativa. Pertanto, sono stati presi in considerazione diversi tipi di cellule staminali, embrionali o adulte, e di cellule progenitri! ci, al fine di utilizzarle in ingegneria dei tessuti. Per queste tecnologie risulta indispensabile l'impiego di bioreattori, atti a riprodurre, nelle culture cellulari, le condizioni dinamiche chimico-fisiche proprie dell'ambiente tissutale naturale, ed a consentire la valutazione delle risposte delle strutture bioingegnerizzate a differenti segnali biochimici e forze meccaniche. PMID: 20109384 [PubMed - in process] | | |
| Biomechanical researches on tissue engineering bone constructed by deproteinated bone.
January 30, 2010 at 6:56 AM
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| | Biomechanical researches on tissue engineering bone constructed by deproteinated bone. Chin J Traumatol. 2010 Feb;13(1):32-6 Authors: Jian YK, Tian XB, Li QH, Li B, Peng Z, Zhao WF, Wang YZ, Yang Z Objective: To study biomechanical changes of newly formed bones 24 weeks after repairing large defects of long bones of goats using heterogeneous deproteinated bone (DPB) prepared by modified methods as an engineering scaffold. Methods: According to a fully randomized design, 18 goats were evenly divided into three groups: normal bone control group (Group A), autologous bone group (Group B) and experimental group (Group C). Each goat in Groups B and C were subjected to the periosteum and bone defect at middle-lower part of the right tibia (20% of the whole tibia in length), followed by autologous bone or DPB plus autologous MSCs + rhBMP2 implantation, respectively and semi-ring slot fixation; while goats in Group A did not perform osteotomy. At 24 weeks after surgery, biomechanical tests were carried out on the tibias. Results: At 24 weeks after surgery, the results of anti-compression test on tibias in three groups were recorded by a functional recorder presented! as linear pressure-deformation curve. The shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values were 10.74 MPa+/-1.23 MPa, 10.11 MPa+/-1.35 MPa and 10.22 MPa+/-1.32 MPa and fracture compression rates were 26.82%+/-0.87%, 27.17%+/-0.75% and 28.22%+/-1.12% in Groups A, B and C, respectively. Comparisons of anti-compression ultimate pressures and fracture compression rates among three groups demonstrated no significant difference (P(AB) equal to 0.415, P(BC) equal to 0.494). Three-point anti-bend test on tibias was recorded as load-deformation curves, and the shapes of the curves and their change tendency were similar among three groups. The ultimate pressure values of the anti-bend test were 481.52 N+/-12.45 N, 478.34 N+/-14.68 N and 475.62 N+/-13.41 N and the fracture bend rates were 2.62 mm+/-0.12 mm, 2.61 mm+/-0.15 mm and 2.81 mm+/-0.13 mm in Groups A, B and C, respectively. There was no significant difference between! groups (P(AB) equal to 0.7, P(BC) equal to 0.448). The ultima! te anti- torsion torque values were 6.55 Nm+/-0.25 Nm, 6.34 Nm+/-0.18 Nm and 6.42 Nm+/-0.21 Nm and fracture torsion rates were 29.51 degree+/-1.64degree, 28.88 degree+/-1.46 degree and 28.81 degree+/-1.33 degree in Groups A, B and C, respectively. There was no significant difference between groups (P(AB) equal to 0.123, P(BC) equal to 0.346). Conclusions: The biomechanical characteristics of newly formed bones from heterogeneous DPB for repairing large segmental long bone defect are comparable to those of normal bones and autologous bones. DPB has the potential for clinical usage as bone graft material. PMID: 20109365 [PubMed - in process] | | |
| Growth of human septal chondrocytes in fibrin scaffolds.
January 30, 2010 at 6:56 AM
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| | Growth of human septal chondrocytes in fibrin scaffolds. Am J Rhinol Allergy. 2010 Jan-Feb;24(1):19-22 Authors: Watson D, Sage A, Chang AA, Schumacher BL, Sah RL BACKGROUND: Tissue engineering of nasal septal cartilage has been the focus of research owing to its superior structural rigidity and ease of harvest. In vitro constructs formed from septal chondrocytes using fibrin glue within a polyglycolic acid (PGA) scaffold have been shown to be viable, but their cellular growth and expression of differentiated features still have not been quantified. In this study, we evaluated cellular proliferation and production of cartilaginous extracellular matrix (ECM) components in fibrin glue preparations within a PGA scaffold. METHODS: Human chondrocytes were expanded for one passage in monolayer in culture medium. The cells were then grown in (1) fibrinogen, (1/2)x-thrombin, (1/2)x (F/2:T/2); (2) fibrinogen, 1/10x-thrombin, 1/10x (F/10:T/10); (3) fibrinogen, 1x-thrombin, 1/100x (F/1:T/100). RESULTS: Cellular proliferation and glycosaminoglycan (GAG) production per cell were highest in the F/2:T/2 preparations. Greater proliferation! was seen in chondrocyte-fibrin composites seeded onto the PGA scaffold when compared with chondrocytes seeded onto the PGA scaffold alone. No significant difference in GAG production was seen. CONCLUSION: The addition of fibrin glue to chondrocytes seeded onto a PGA scaffold results in increased cellular proliferation while maintaining production of ECM components. Long-term stable fibrin gels in combination with PGA scaffolds may facilitate generation of cartilaginous tissue for use in reconstructive surgery. PMID: 20109313 [PubMed - in process] | | |
| Self-Assembly and Tissue Fusion of Toroid-Shaped Minimal Building Units.
January 30, 2010 at 6:56 AM
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| | Self-Assembly and Tissue Fusion of Toroid-Shaped Minimal Building Units. Tissue Eng Part A. 2010 Jan 28; Authors: Livoti C, Morgan JR A significant challenge of tissue engineering is to build tissues whose size is not limited by diffusion. We are investigating the use of scaffold-free lumen containing toroid-shaped microtissues as minimal building units. Mono-dispersed H35 cells, a rat hepatocyte cell line, were seeded onto micro-molded agarose, forming self-assembled multi-cellular toroids within 48 hours. Toroid and lumen diameter were easily controlled by micro-mold design, and toroid thickness was controlled by seeding density. When harvested, toroids were stable, but underwent predictable changes over time with their lumens narrowing. When brought into contact, these building units fused in the x-y plane, forming a double-lumen structure, as well as the z plane, forming a tubular structure, which completed within 72 hours. Large, multi-luminal structures were assembled by multi-dimensional fusion of many toroids. Toroid settling was not entirely random, with most toroids lying flat with the! ir lumens oriented along the z axis. The rapid production of toroid building units of controlled dimension and lumen size that undergo predictable changes and that can be fused to form larger structures is a step closer to tissue engineering large porous 3D tissues with high cell density. PMID: 20109063 [PubMed - as supplied by publisher] | | |
| Flexor Tendon Tissue Engineering: Bioreactor Cyclic Strain Increases Construct Strength.
January 30, 2010 at 6:56 AM
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| | Flexor Tendon Tissue Engineering: Bioreactor Cyclic Strain Increases Construct Strength. Tissue Eng Part A. 2010 Jan 28; Authors: Saber S, Zhang AY, Ki SH, Lindsey DP, Smith L, Riboh J, Pham H, Chang J Mutilating injuries of the hand and upper extremity result in tendon losses too great to be replaced by autologous grafts. The goal of this study was to use tissue engineering techniques to produce additional tendon material. We used a custom bioreactor to apply cyclic mechanical loading onto tissue engineered tendon constructs to study ultimate tensile stress (UTS) and elastic modulus (E). Constructs used were acellularized rabbit hindpaw FDP equivalents reseeded with tenocytes or left unseeded. Tendon constructs were subjected to a stretch force of 1.25N over a 5-day course. Seeded tendon constructs that were exposed to bioreactor loading had a significantly increased UTS (71.17 +/- 14.15 N) compared to non-loaded controls (35.69 +/- 5.62 N); (p = 0.001). Similarly, seeded constructs exposed to bioreactor loading also had a significantly higher E (1091 +/- 169 MPa) compared to non-loaded controls (632 +/- 86 MPa); (p = 0.001). This study shows that cyclic loadin! g of tendon constructs increases the ultimate tensile stress and elastic modulus of seeded constructs. The use of the bioreactor may therefore accelerate the in vitro production of strong, non-immunogenic tendon material that can potentially be used clinically to reconstruct significant tendon losses. PMID: 20109062 [PubMed - as supplied by publisher] | | |
| Reversible adipose tissue enlargement induced by external tissue suspension: possible contribution of basic fibroblast growth factor for preservation of enlarged tissue.
January 30, 2010 at 6:56 AM
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| | Reversible adipose tissue enlargement induced by external tissue suspension: possible contribution of basic fibroblast growth factor for preservation of enlarged tissue. Tissue Eng Part A. 2010 Jan 28; Authors: Kato H, Suga H, Eto H, Araki J, Aoi N, Doi K, Higashino T, Iida T, Tabata Y, Yoshimura K Various kinds of tissue expansion have been performed clinically with internal devices, but external expansion has not previously been investigated. We applied continuous external force on skin tissue in a mouse model. Four weeks of external suspension caused enlargement of the subcutaneous tissue, particularly adipose tissue, though the enlargement was reversible. We found that the enlarged tissue volume could be adequately sustained with controlled release of basic fibroblast growth factor (bFGF), administered at the time the device was removed. Ki67+ proliferating cells, perilipin+ small adipocytes, lectin+ capillaries, and glycerol-3-phosphate dehydrogenase activity in the tissue increased during the expansion process, indicating dynamic adipose remodeling with adipogenesis and angiogenesis. Histological analyses revealed that vessels had elongated in the direction of the external force. Adipose-resident progenitor cells (adipose-derived stem/stromal cells) we! re the primary proliferating cell population involved in the remodeling process, particularly in the superficial layer. Treatment with b-FGF did not enhance the small adipocyte number, but promoted angiogenesis; this mechanism may contribute to the preservation of enlarged tissue. Our results suggested that external tissue suspension induced adipose tissue enlargement by activating resident progenitor cells and that this external suspension approach, combined with controlled release of bFGF, has therapeutic potential for soft tissue engineering. PMID: 20109059 [PubMed - as supplied by publisher] | | |
| Synthesis and Characterization of Photocurable Polyamidoamine Dendrimer Hydrogels as a Versatile Platform for Tissue Engineering and Drug Delivery.
January 30, 2010 at 6:56 AM
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| | Synthesis and Characterization of Photocurable Polyamidoamine Dendrimer Hydrogels as a Versatile Platform for Tissue Engineering and Drug Delivery. Biomacromolecules. 2010 Jan 28; Authors: Desai PN, Yuan Q, Yang H In this work, we describe a novel polyamidoamine (PAMAM) dendrimer hydrogel (DH) platform with potential for tissue engineering and drug delivery. With PAMAM dendrimer G3.0 being the underlying carrier, polyethylene glycol (PEG) chains of various lengths (MW = 1500, 6000, or 12000 g mol(-1)) were coupled to the dendrimer to different extents, and the resulting PEGylated PAMAM dendrimers were further coupled with acrylate groups to yield photoreactive dendrimer macromonomers for gel formation. It was found that gelation based on photoreactive PAMAM G3.0 macromonomers was restricted by the degree of PEGylation, PEG chain length, and the distribution of acrylate groups on the dendrimer surface. Further, the architecture of the photoreactive macromonomers affects the structural stability and swelling of the resultant networks. A completely cross-linked network (DH-G3.0-12000(H)) with a high water swelling ratio was created by UV-curing of PAMAM dendrimer G3.0 coupled ! with 28 PEG 12000 chains in the presence of the eosin Y-based photoinitiating system. The disintegration of DH-G3.0-12000(H) was pH-insensitive. DH-G3.0-12000(H) was found to have similar cytocompatibility to un-cross-linked G3.0-12000(H) but a significantly lower cellular uptake by macrophages. With PAMAM dendrimer G3.5 being the underlying carrier, the dendrimer modified with 43 PEG 1500 chains was able to form a completely cross-linked network (DH-G3.5-1500(H)) by UV-curing in the presence of the eosin Y-based photoinitiating system. DH-G3.5-1500(H) exhibited pH-dependent disintegration. Its disintegration ratio increased with pH. PAMAM dendrimer hydrogels uniquely express the structural characteristics of both PEG hydrogel and PAMAM dendrimer and have potential for various applications in tissue engineering and drug delivery. PMID: 20108892 [PubMed - as supplied by publisher] | | |
| Characterization of primary dental pulp cells in vitro.
January 30, 2010 at 6:56 AM
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| | Characterization of primary dental pulp cells in vitro. Pediatr Dent. 2009 Nov-Dec;31(7):467-71 Authors: Coppe C, Zhang Y, Den Besten PK PURPOSE: This study's purpose was to characterize dental pulp cells from human primary teeth and determine their ability to induce differentiation of oral epithelial cells. METHODS: Dental pulp cells were isolated from freshly extracted primary incisors, digested with 4 mg/ml collogenase/dispase, and grown in Dulbecco's modified Eagle's medium with 10 percent fetal bovine serum. Stem cell populations were identified by immunocytochemical staining for STRO-1 and CD146 and fluorescence activated cell sorting. To determine whether primary pulp cells can signal epithelium, the pulp cells were grown in coculture with human fetal oral epithelial cells. After 3 days, the cocultured cells were collected and analyzed for amelogenin expression by polymerAse chain reaction (PCR) and immunocytochemical staining. RESULTS: Immunofluorescence and fluorescence activated cell sorting of STRO-1+ cells showed this stem cell population to be approximately 2 percent of the total popul! ation. Growth-arrested primary dental pulp cells grown in coculture with oral epithelial cells showed expression of Amelogenin by immunocytochemistry and PCR. Oral epithelial cells alone were amelogenin immunonegative. CONCLUSIONS: Primary tooth dental pulp cells contain less than 2 percent stem cells. Cells within the primary tooth pulp can promote epithelial cell differentiation toward an ameloblast phenotype, suggesting the potential use of this heterogeneous population of cells in cell-mediated enamel tissue engineering. PMID: 20108736 [PubMed - in process] | | |
| Bone morphogenetic proteins and tissue engineering: future directions.
January 30, 2010 at 6:56 AM
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| | Bone morphogenetic proteins and tissue engineering: future directions. Injury. 2009 Dec;40 Suppl 3:S67-76 Authors: Calori GM, Donati D, Di Bella C, Tagliabue L As long as bone repair and regeneration is considered as a complex clinical condition, the administration of more than one factor involved in fracture healing might be necessary. The effectiveness or not of bone morphogenetic proteins (BMPs) in association with other growth factors and with mesenchymal stem cells in bone regeneration for fracture healing and bone allograft integration is of great interest to the scientific community. In this study we point out possible future developments in BMPs, concerning research and clinical applications. PMID: 20082795 [PubMed - in process] | | |
| Bone morphogenetic proteins in soft-tissue reconstruction.
January 30, 2010 at 6:56 AM
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| | Bone morphogenetic proteins in soft-tissue reconstruction. Injury. 2009 Dec;40 Suppl 3:S17-20 Authors: Obert L, Lepage D, Gindraux F, Garbuio P Different options are reviewed in the field of musculoskeletal tissue reconstruction, from the addition of biological actors (cells, growth factors, biological or artificial scaffolds) to the application of gene therapy or tissue engineering. Growth factors can enable innovative solutions to treat such disease if we can extrapolate to soft tissue the promising results obtained in bone reconstruction with bone morphogenetic proteins. However, as in bone reconstruction, soft-tissue regeneration will depend on the drug delivery carrier, the scaffold for the newly formed tissue, the dose of growth factor and the animal model, which must all be explored before extrapolation to clinical problems. PMID: 20082785 [PubMed - in process] | | | |
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