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| Chondroitin-6-sulfate incorporation and mechanical stimulation increase MSC-collagen sponge construct stiffness.
February 10, 2010 at 6:50 AM
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| | Chondroitin-6-sulfate incorporation and mechanical stimulation increase MSC-collagen sponge construct stiffness. J Orthop Res. 2010 Feb 8; Authors: Kinneberg KR, Nirmalanandhan VS, Juncosa-Melvin N, Powell HM, Boyce ST, Shearn JT, Butler DL Using functional tissue engineering principles, our laboratory has produced tendon repair tissue which matches the normal patellar tendon force-displacement curve up to 32% of failure. This repair tissue will need to withstand more strenuous activities, which can reach or even exceed 40% of failure force. To improve the linear stiffness of our tissue engineered constructs (TECs) and tissue engineered repairs, our lab is incorporating the glycosaminoglycan chondroitin-6-sulfate (C6S) into a type I collagen scaffold. In this study, we examined the effect of C6S incorporation and mechanical stimulation cycle number on linear stiffness and mRNA expression (collagen types I and III, decorin and fibronectin) for mesenchymal stem cell (MSC)-collagen sponge TECs. The TECs were fabricated by inoculating MSCs at a density of 0.14 x 10(6) cells/construct onto pre-cut scaffolds. Primarily type I collagen scaffold materials, with or without C6S, were cultured using mechanical ! stimulation with three different cycle numbers (0, 100, or 3,000 cycles/day). After 2 weeks in culture, TECs were evaluated for linear stiffness and mRNA expression. C6S incorporation and cycle number each played an important role in gene expression, but only the interaction of C6S incorporation and cycle number produced a benefit for TEC linear stiffness. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 20143407 [PubMed - as supplied by publisher] | | |
| Transdifferentiation potentiality of human Wharton's jelly stem cells towards vascular endothelial cells.
February 10, 2010 at 6:50 AM
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| | Transdifferentiation potentiality of human Wharton's jelly stem cells towards vascular endothelial cells. J Cell Physiol. 2010 Feb 8; Authors: Alaminos M, Pérez-Köhler B, Garzón I, García-Honduvilla N, Romero B, Campos A, Buján J Human Wharton's jelly stem cells (HWJSC) emerged as a potential source of viable cells for use in tissue engineering. In this work, we have analyzed the transdifferentiation capabilities of HWJSC towards transdifferentiated endothelial-like cells (Tr-ELC) in order to establish the potential usefulness of these cells in vascular tissue engineering. Our results show that Tr-ELC became more polygonal and less proliferative than HWJSC, resembling the structure and proliferation rate of the endothelial cells. In addition, the markers of mesenchymal undifferentiation CD9, E-cad, PODXL, and SSEA-4 are downregulated in Tr-ELC, suggesting that these cells can be in the process of adult differentiation. Besides, RT-PCR and microarray analyses revealed that some genes with a role in defining the endothelial phenotype and structure are upregulated (VEGF-R1, EDF1, AAMP, CD31, CD34, CDH5, and ICAM2) or downregulated (VEGF) in Tr-ELC, although a number of genes related to releva! nt endothelial cell functions (CD36, ECE2, VWF, THBD, PGI2, ECE1, and ACE) did not change or were only partially induced. All this implies that HWJSC are able to efficiently transdifferentiate towards Tr-ELC at the phenotypical level following a hierarchical pattern of gene activation, with an earlier induction of morphological and phenotypical genes. J. Cell. Physiol. (c) 2010 Wiley-Liss, Inc. PMID: 20143331 [PubMed - as supplied by publisher] | | |
| The consolidation behavior of silk hydrogels.
February 10, 2010 at 6:50 AM
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| | The consolidation behavior of silk hydrogels. J Mech Behav Biomed Mater. 2010 Apr;3(3):278-289 Authors: Kluge JA, Rosiello NC, Leisk GG, Kaplan DL, Luis Dorfmann A Hydrogels have mechanical properties and structural features that are similar to load-bearing soft tissues including intervertebral disc and articular cartilage, and can be implanted for tissue restoration or for local release of therapeutic factors. To help predict their performance, mechanical characterization and mathematical modeling are the available methods for use in tissue engineering and drug delivery settings. In this study, confined compression creep tests were performed on silk hydrogels, over a range of concentrations, to examine the phenomenological behavior of the gels under a physiological loading scenario. Based on the observed behavior, we show that the time-dependent response can be explained by a consolidation mechanism, and modeled using Biot's poroelasticity theory. Two observations are in strong support of this modeling framework, namely, the excellent numerical agreement between increasing load step creep data and the linear Terzaghi theory! , and the similar values obtained from numerical simulations and direct measurements of the permeability coefficient. The higher concentration gels (8% and 12% w/v) clearly show a strain-stiffening response to creep loading with increasing loads, while the lower concentration gel (4% w/v) does not. A nonlinear elastic constitutive formulation is employed to account for the stiffening. Furthermore, an empirical formulation is used to represent the deformation-dependent permeability. PMID: 20142112 [PubMed - as supplied by publisher] | | |
| Improvement of the microstructure and mechanical properties of bioceramic scaffolds using electrohydrodynamic spraying with template modification.
February 10, 2010 at 6:50 AM
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| | Improvement of the microstructure and mechanical properties of bioceramic scaffolds using electrohydrodynamic spraying with template modification. J Mech Behav Biomed Mater. 2010 Apr;3(3):230-239 Authors: Muthutantri AI, Edirisinghe MJ, Boccaccini AR Porous scaffolds play a key role in tissue engineering (TE) approaches and new processing methods and materials are constantly being developed to cater for the wide range of specifications and requirements. Electrospraying is a relatively new processing method used for producing open-pore scaffolds. In this work, the electrospraying technique was manipulated to make the process more efficient, and the effect of spraying time on the pore size and strut thickness of zirconia scaffolds was explored. Scaffolds of adequate pore size and interconnectivity, with an average compressive strength of approximately 7.5 MPa, by electrospraying for only 10 min are reported. The effect of modifying the sacrificial template on the microstructure and mechanical properties of the sintered scaffolds was also investigated. A combination of template surface hydroxylation and improved conductivity produced a thicker ceramic coating, leading to enhanced mechanical properties. PMID: 20142107 [PubMed - as supplied by publisher] | | |
| Neocartilage Formation in 1 g, Simulated, and Microgravity Environments: Implications for Tissue Engineering.
February 10, 2010 at 6:50 AM
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| | Neocartilage Formation in 1 g, Simulated, and Microgravity Environments: Implications for Tissue Engineering. Tissue Eng Part A. 2010 Feb 8; Authors: Stamenković V, Keller G, Nesic D, Cogoli A, Grogan SP Aim: The aim of this study was to analyze and compare the deposition of cartilage-specific extracellular matrix components and cellular organization in scaffold-free neocartilage produced in microgravity and simulated microgravity. Methods: Porcine chondrocytes were seeded (100 x 10(6)/mL) into cylindrical culture chambers (n = 8) and cultured in the following environments: (i) microgravity during the Flight 7S (Cervantes mission) on the International Space Station (ISS), (ii) simulated microgravity in a random positioning machine (RPM), and (iii) normal gravity (1 g, control). After 16 days, each neocartilage tissue was processed for histology, immunohistochemistry, quantitative real-time reverse transcriptase-polymerase chain reaction, and histomorphometric analysis. Results: Weaker extracellular matrix staining of ISS neocartilage tissue was noted compared with both Earth-cultivated tissues. Higher collagen II/I expression ratios were observed in ISS samples co! mpared with control tissue. Conversely, higher aggrecan/versican gene expression profiles were seen in control 1 g samples compared with microgravity samples. Cell density produced in microgravity was significantly reduced compared with the normal gravity neocartilage tissues. Conclusion: Tissue cultivated on the RPM showed intermediate characteristics compared with ISS and 1 g conditions. These data indicate that the RPM system does not sustain microgravity. Although microgravity impacts the development of in vitro generated cartilage, simulated microgravity using the RPM may be a useful tool to produce cartilaginous tissue grafts with fewer cells. PMID: 20141387 [PubMed - as supplied by publisher] | | |
| Protein-Engineered Biomaterials: Highly Tunable Tissue Engineering Scaffolds.
February 10, 2010 at 6:50 AM
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| | Protein-Engineered Biomaterials: Highly Tunable Tissue Engineering Scaffolds. Tissue Eng Part B Rev. 2010 Feb 8; Authors: Sengupta D, Heilshorn SC A common goal in tissue engineering is to attain the ability to tailor specific cell-scaffold interactions and thereby gain control over cell behavior. The tunable nature of protein-engineered biomaterials enables independent tailoring of a range of biomaterial properties, creating an attractive alternative to synthetic polymeric scaffolds or harvested natural scaffolds. Protein-engineered biomaterials are comprised of modular peptide domains with various functionalities that are encoded into a DNA plasmid, transfected into an organism of choice, and expressed and purified to yield a biopolymer with exact molecular-level sequence specification. Because of the modular design strategy of protein-engineered biomaterials, these scaffolds can be easily modified to enable optimization for specific tissue engineering applications. By including multiple peptide domains with different functionalities in a single, modular biomaterial, the scaffolds can be designed to mimic ! the diverse properties of the natural extracellular matrix, including cell adhesion, cell signaling, elasticity, and biodegradability. Recently, the field of protein-engineered biomaterials has expanded to include functional modules that are not normally present in the extracellular matrix, thus expanding the scope and functionality of these materials. For example, these modules can include noncanonical amino acids, inorganic-binding domains, and DNA-binding sequences. The modularity, tunability, and sequence specificity of protein-engineered biomaterials make them attractive candidates for use as substrates for a variety of tissue engineering applications. PMID: 20141386 [PubMed - as supplied by publisher] | | |
| Animal serum-free expansion and differentiation of human mesenchymal stromal cells.
February 10, 2010 at 6:50 AM
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| | Animal serum-free expansion and differentiation of human mesenchymal stromal cells. Cytotherapy. 2010 Feb 8; Authors: Felka T, Schäfer R, De Zwart P, Aicher WK Abstract Background aims. Mesenchymal stromal cells (MSC) are attracting increasing interest for possible application in cell therapies. Fetal calf serum (FCS) is widely utilized for cell culture, but its use in the context of clinical applications is associated with too many risks. Therefore we tested FCS-free media for the expansion and differentiation of MSC in compliance with the European good manufacturing practice (GMP) regulations for medicinal products. Methods. MSC expansion medium was modified by replacing FCS with human plasma and platelet extract. Cells were characterized according to the defined minimal criteria for multipotent MSC. For chondrogenic differentiation, serum-free micromass cultures were employed. For adipogenic and osteogenic differentiation, the FCS was replaced by human plasma. After 28 days of incubation in differentiation media, cells were analyzed by cytochemical and immunohistochemical staining. Furthermore, mRNA expression of chon! drogenic, adipogenic and osteogenic markers was investigated by quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Results. Expansion and differentiation of MSC under FCS-free conditions yielded cells with chondrogenic, adipogenic and osteogenic phenotypes and a characteristic gene expression. Chondrocytes in micromass pellets revealed an accumulation of proteoglycans and type II collagen as well as a significantly increased mRNA expression of chondrogenic marker genes. The adipocytes displayed Oil red O staining and expressed peroxisome proliferator-activated receptor gamma(2) (ppARgamma2) and lipoprotein lipase (LPL) mRNA. The osteoblasts were positive for von Kossa staining and expressed mRNA of osteogenic marker genes. The results did not indicate any spontaneous differentiation. Conclusions. Human plasma is a suitable FCS replacement for the expansion and differentiation of MSC, providing a feasible alternative for tissue engineering with GMP-compa! tible protocols. PMID: 20141338 [PubMed - as supplied by publisher] | | |
| Human mandible bone defect repair by the grafting of dental pulp stem/progenitor cells and collagen sponge biocomplexes.
February 10, 2010 at 6:50 AM
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| | Human mandible bone defect repair by the grafting of dental pulp stem/progenitor cells and collagen sponge biocomplexes. Eur Cell Mater. 2009;18:75-83 Authors: d'Aquino R, De Rosa A, Lanza V, Tirino V, Laino L, Graziano A, Desiderio V, Laino G, Papaccio G In this study we used a biocomplex constructed from dental pulp stem/progenitor cells (DPCs) and a collagen sponge scaffold for oro-maxillo-facial (OMF) bone tissue repair in patients requiring extraction of their third molars. The experiments were carried out according to our Internal Ethical Committee Guidelines and written informed consent was obtained from the patients. The patients presented with bilateral bone reabsorption of the alveolar ridge distal to the second molar secondary to impaction of the third molar on the cortical alveolar lamina, producing a defect without walls, of at least 1.5 cm in height. This clinical condition does not permit spontaneous bone repair after extraction of the third molar, and eventually leads to loss also of the adjacent second molar. Maxillary third molars were extracted first for DPC isolation and expansion. The cells were then seeded onto a collagen sponge scaffold and the obtained biocomplex was used to fill in the inju! ry site left by extraction of the mandibular third molars. Three months after autologous DPC grafting, alveolar bone of patients had optimal vertical repair and complete restoration of periodontal tissue back to the second molars, as assessed by clinical probing and X-rays. Histological observations clearly demonstrated the complete regeneration of bone at the injury site. Optimal bone regeneration was evident one year after grafting. This clinical study demonstrates that a DPC/collagen sponge biocomplex can completely restore human mandible bone defects and indicates that this cell population could be used for the repair and/or regeneration of tissues and organs. PMID: 19908196 [PubMed - indexed for MEDLINE] | | |
| Interactions between endothelial cells and electrospun methacrylic terpolymer fibers for engineered vascular replacements.
February 10, 2010 at 6:50 AM
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| | Interactions between endothelial cells and electrospun methacrylic terpolymer fibers for engineered vascular replacements. J Biomed Mater Res A. 2009 Dec 15;91(4):1131-9 Authors: Veleva AN, Heath DE, Johnson JK, Nam J, Patterson C, Lannutti JJ, Cooper SL A compliant terpolymer made of hexylmethacrylate (HMA), methylmethacrylate (MMA), and methacrylic acid (MAA) intended for use in small diameter vascular graft applications has been developed. The mechanical properties and in vitro biostability of this terpolymer have been previously characterized. The goal of this investigation was to examine the interactions between endothelial cells and the new terpolymer and to evaluate endothelial cell function. Electrospinning was used to produce both oriented and random terpolymer fiber scaffolds. Smooth solution cast films and tissue culture polystyrene were used as negative and positive controls, respectively. Human blood outgrowth endothelial cells and human umbilical vein endothelial cells were incubated with the test and control samples and characterized with respect to initial cell attachment, proliferation, viability, and maintenance of the endothelial cell phenotype. It was found that the terpolymer is cytocompatible! allowing endothelial cell growth, with random fibers being more effective in promoting enhanced cellular activities than oriented fibers. In addition, endothelial cells cultured on these substrates appeared to maintain their phenotype. The results from this study demonstrate that electrospun HMA:MMA:MAA terpolymer has the potential to be used successfully in fabricating small diameter blood vessel replacements. PMID: 19148926 [PubMed - indexed for MEDLINE] | | |
| Effects of Schwann cell alignment along the oriented electrospun chitosan nanofibers on nerve regeneration.
February 10, 2010 at 6:50 AM
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| | Effects of Schwann cell alignment along the oriented electrospun chitosan nanofibers on nerve regeneration. J Biomed Mater Res A. 2009 Dec 15;91(4):994-1005 Authors: Wang W, Itoh S, Konno K, Kikkawa T, Ichinose S, Sakai K, Ohkuma T, Watabe K We have constructed a chitosan nonwoven nanofiber mesh tube consisting of oriented fibers by the electrospinning method. The efficacy of oriented nanofibers on Schwann cell alignment and positive effect of this tube on peripheral nerve regeneration were confirmed. The physical properties of the chitosan nanofiber mesh sheets prepared by electrospinning with or without fiber orientation were characterized. Then, immortalized Schwann cells were cultured on these sheets. Furthermore, the chitosan nanofiber mesh tubes with or without orientation, and bilayered chitosan mesh tube with an inner layer of oriented nanofibers and an outer layer of randomized nanofibers were bridgegrafted into rat sciatic nerve defect. As a result of fiber orientation, the tensile strength along the axis of the sheet increased. Because Schwann cells aligned along the nanofibers, oriented fibrous sheets could exhibit a Schwann cell column. Functional recovery and electrophysiological recover! y occurred in time in the oriented group as well as in the bilayered group, and approximately matched those in the isograft. Furthermore, histological analysis revealed that the sprouting of myelinated axons occurred vigorously followed by axonal maturation in the isograft, oriented, and bilayered group in the order. The oriented chitosan nanofiber mesh tube may be a promising substitute for autogenous nerve graft. PMID: 19097155 [PubMed - indexed for MEDLINE] | | |
| Cellular Histone Modification Patterns Predict Prognosis and Treatment Response in Resectable Pancreatic Adenocarcinoma: Results From RTOG 9704.
February 10, 2010 at 6:21 AM
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| | Cellular Histone Modification Patterns Predict Prognosis and Treatment Response in Resectable Pancreatic Adenocarcinoma: Results From RTOG 9704. J Clin Oncol. 2010 Feb 8; Authors: Manuyakorn A, Paulus R, Farrell J, Dawson NA, Tze S, Cheung-Lau G, Hines OJ, Reber H, Seligson DB, Horvath S, Kurdistani SK, Guha C, Dawson DW PURPOSE: Differences in cellular levels of histone modifications have predicted clinical outcome in certain cancers. Here, we studied the prognostic and predictive value of three histone modifications in pancreatic adenocarcinoma. METHODS: Tissue microarrays (TMAs) from two pancreatic adenocarcinoma cohorts were examined, including those from a 195-patient cohort from Radiation Therapy Oncology Group trial RTOG 9704, a multicenter, phase III, randomized treatment trial comparing adjuvant gemcitabine with fluorouracil and a 140-patient cohort of patients with stage I or II cancer from University of California, Los Angeles Medical Center. Immunohistochemistry was performed for histone H3 lysine 4 dimethylation (H3K4me2), histone H3 lysine 9 dimethylation (H3K9me2), and histone H3 lysine 18 acetylation (H3K18ac). Positive tumor cell staining for each histone modification was used to classify patients into low- and high-staining groups, which were related to clinicopa! thologic parameters and clinical outcome measures. RESULTS: Low cellular levels of H3K4me2, H3K9me2, or H3K18ac were each significant and independent predictors of poor survival in univariate and multivariate models, and combined low levels of H3K4me2 and/or H3K18ac were the most significant predictor of overall survival (hazard ratio, 2.93; 95% CI, 1.78 to 4.82) in the University of California, Los Angeles cohort. In subgroup analyses, histone levels were predictive of survival specifically for those patients with node-negative cancer or for those patients receiving adjuvant fluorouracil, but not gemcitabine, in RTOG 9704. CONCLUSION: Cellular levels of histone modifications define previously unrecognized subsets of patients with pancreatic adenocarcinoma with distinct epigenetic phenotypes and clinical outcomes and represent prognostic and predictive biomarkers that could inform clinical decisions, including the use of fluorouracil chemotherapy. PMID: 20142597 [PubMed - as supplied by publisher] | | |
| Mesenchymal stem cells induce a weak immune response in the rat striatum after allo or xenotransplantation.
February 10, 2010 at 6:21 AM
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| | Mesenchymal stem cells induce a weak immune response in the rat striatum after allo or xenotransplantation. J Cell Mol Med. 2009 Aug;13(8b):2547-2558 Authors: Rossignol J, Boyer C, Thinard R, Remy S, Dugast AS, Dubayle D, Dey ND, Boeffard F, Delecrin J, Heymann D, Vanhove B, Anegon I, Naveilhan P, Dunbar GL, Lescaudron L Mesenchymal stem cells (MSCs) have attracted attention for their potential use in regenerative medicine such as brain transplantation. As MSCs are considered to be hypoimmunogenic, transplanted MSCs should not trigger a strong host inflammatory response. To verify this hypothesis, we studied the brain immune response after transplantation of human or rat MSCs into the rat striatum and MSC fate at days 5, 14, 21 and 63 after transplantation. Flow cytometry analysis indicated that both MSCs express CD90 and human leucocyte antigen (MHC) class I, but no MHC class II molecules. They do not express CD45 or CD34 antigens. However, MSC phenotype varies with passage number. Human MSCs have mRNAs for interleukin (IL)-6, IL-8, IL-12, tumour necrosis factor (TNF)-alpha and TGF-beta(1), whereas rat MSCs express IL-6-, IL-10-, IL-12- and TGF-beta(1)-mRNAs. The quantification shows higher levels of mRNAs for the anti-inflammatory molecules IL-6 and TGF-beta(1) than for pro-infl! ammatory cytokines IL-8 and IL-12; ELISA analysis showed no IL-12 whereas TGF-beta(1) and IL-6 were detected. Transplant size did not significantly vary between 14 and 63 days after transplantation, indicating an absence of immune rejection of the grafts. Very few mast cells and moderate macrophage and microglial infiltrations, observed at day 5 remained stable until day 63 after transplantation in both rat and human MSC grafts. The observations of very few dendritic cells, T alphabeta-cells, and no T gammadelta-lymphocytes, all three being associated with Tp rejection in the brain, support the contention that MSCs are hypoimmunogenic. Our results suggest that MSCs are of great interest in regenerative medicine in a (xeno)transplantation setting. PMID: 20141619 [PubMed - as supplied by publisher] | | | | 
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