|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Counterion-Induced Modulation in the Antimicrobial Activity and Biocompatibility of Amphiphilic Hydrogelators: Influence of in-Situ-Synthesized Ag-Nanoparticle on the Bactericidal Property. Langmuir. 2011 Mar 29; Authors: Dutta S, Shome A, Kar T, Das PK The necessity for the development of new antimicrobial agents due to the ever increasing threat from microbes is causing a rapid surge in research. In the present work, we have shown the efficient antimicrobial activity of a series of amino acid-based hydrogelating amphiphiles through alteration in their counterion. The subtle variation in the counterion from chloride to various organic carboxylates had a significant impact on the antimicrobial properties with notable improvement in biocompatibility toward mammalian cells. Incorporation of a hydrophobic moiety in the counterion augmented the antibacterial property of the amphiphilic hydrogelator as minimum inhibitory concentration (MIC) against the Gram-positive bacterial strain, Bacillus subtilis decreased up to 5-fold (with respect to the chloride) in the case of n-hexanoate. These counterion-varied amphiphilic hydrogelators were also found to be effective against fungal strains (Candida albicans and Saccharomyces cerevisiae) where they exhibited MICs in the range of 1.0-12.5 μg/mL. To widen the spectrum of antibacterial activity, particularly against Gram-negative bacteria, silver nanoparticles (AgNPs) were synthesized in situ within the supramolecular assemblies of the carboxylate hydrogelators. These AgNP-amphiphile soft-nanocomposites showed bactericidal property against both Gram-positive and Gram-negative bacteria. Encouragingly, these carboxylate hydrogelators showed superior biocompatibility toward mammalian cells, HepG2 and NIH3T3, as compared to the chloride analogue at a concentration range of 10-200 μg/mL. Importantly, the AgNP composites also showed sufficient viability to mammalian cells. Because of the intrinsic hydrogelation ability of these counterion-varied amphiphiles, the resulting soft materials and the nanocomposites could find applications in biomedicine and tissue engineering. PMID: 21446701 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In situ endothelialization of intravascular stents from progenitor stem cells coated with nanocomposite and functionalized biomolecules. Biotechnol Appl Biochem. 2011 Jan;58(1):2-13 Authors: Motwani MS, Rafiei Y, Tzifa A, Seifalian AM Owing to their noninvasive nature, coronary artery stents have become popular demand for patients undergoing percutaneous coronary intervention. Late restenosis, in-stent restenosis, and late thrombosis, all mediated by the denuded endothelium, represent the most recurrent failures of vascular stent induction. Higher patency rates of stents can be achieved by restoring the native internal environment of the vessel-an endothelium monolayer. This active organ inhibits the inflammatory reaction to injury responsible for thrombus and intimal hyperplasia, thereby providing a novel therapeutic option to combat the unacceptably high prevalence of restenosis. As the climax of the nanotechnology era approaches, tissue engineering is being explored by means of exploiting the multipotent abilities of stem cells and their adherence to bioactive surface nanocomposite polymers. The endothelium can be reconstructed from neighboring intact endothelium and adherence of circulating endothelium progenitor cells. The latter takes place via a series of signaling events: mobilization, adhesion, chemoattraction, migration, proliferation, and finally their differentiation in mature endothelial cells. A nanotopography surface can orchestrate endothelium formation, attributable to cellular interactions promoted by its nanosize. This review encompasses the prospect of in situ endothelialization, the mechanisms regulating the process, and the advantages of using a new generation of bioactive nanocomposite materials for coating metal stent scaffolds. PMID: 21446954 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Synthetic conversion of a graded receptor signal into a tunable, reversible switch. Mol Syst Biol. 2011 Mar 29;7:480 Authors: Palani S, Sarkar CA The ability to engineer an all-or-none cellular response to a given signaling ligand is important in applications ranging from biosensing to tissue engineering. However, synthetic gene network 'switches' have been limited in their applicability and tunability due to their reliance on specific components to function. Here, we present a strategy for reversible switch design that instead relies only on a robust, easily constructed network topology with two positive feedback loops and we apply the method to create highly ultrasensitive (n(H)>20), bistable cellular responses to a synthetic ligand/receptor complex. Independent modulation of the two feedback strengths enables rational tuning and some decoupling of steady-state (ultrasensitivity, signal amplitude, switching threshold, and bistability) and kinetic (rates of system activation and deactivation) response properties. Our integrated computational and synthetic biology approach elucidates design rules for building cellular switches with desired properties, which may be of utility in engineering signal-transduction pathways. PMID: 21451590 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of an avidin-biotin binding system on Schwann cells attachment, proliferation, and gene expressions onto electrospun scaffolds. J Biomed Mater Res A. 2011 Mar 29; Authors: Feng S, Yan Z, Guo C, Chen Z, Zhang K, Mo X, Gu Y Effective Schwann cells (SCs) attachment is a prerequisite for the successful construction of tissue-engineered nerve. The present study aimed to investigate the role of an avidin-biotin binding system (ABBS) for neural tissue engineering. The attachment, proliferation, and morphology of biotinylated SCs on avidin-treated scaffolds were examined, and the effects of avidin, biotin, and the avidin-biotin binding system on SCs gene expressions were also studied. The results indicated that the attachment of biotinylated SCs onto avidin-treated scaffolds was promoted obviously within a short time (10 min). Meanwhile, there were no great differences in terms of proliferation and morphology of SCs between the two groups after cultivation for 14 days. The gene expressions of S100, GDNF, BDNF, NGF, CNTF, and PMP22 were up-regulated significantly by biotin rather than aligned scaffolds or avidin. The present study demonstrated that ABBS enhanced the attachment and maturation of SCs onto the electrospun scaffolds without adverse effects on the proliferation of SCs in the long term, suggesting the potential application of ABBS in the neural tissue engineering. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2011. PMID: 21448996 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Release of Bioactive Adeno-Associated Virus from Fibrin Scaffolds: Effects of Fibrin Glue Concentration. Tissue Eng Part A. 2011 Mar 30; Authors: Lee HH, Haleem AM, Yao V, Li J, Xiao X, Chu CR Fibrin glue (FG) is used in a variety of clinical applications and in the laboratory for localized- and sustained-release of factors potentially important for tissue-engineering. However, the effect of different fibrinogen-concentrations on FG-scaffold delivery of bioactive adeno-associated viruses (AAVs) has not been established. This study was performed to test the hypothesis that FG-concentration alters AAV-release profiles, which affect AAV-bioavailability. Gene-transfer efficiency of AAV-GFP released from FG was measured using HEK-293 cells. Bioactivity of AAV-Transforming Growth Factor-Beta1 (TGF-β<sub>1</sub>) released from FG was assessed using the mink lung cell assay, and by measuring induction of cartilage-specific gene-expression in human mesenchymal stem cells (hMSCs). Non-diluted FG had longer clotting-times, smaller pore-sizes, thicker fibers, and slower dissolution-rate, resulting in reduced release of AAV. AAV-release and gene-transfer efficiency was higher with 25%- and 50%-FG than with the 75%- and 100%-FG. AAV-TGF-β<sub>1</sub> released from dilute-FG transduced hMSC resulting in higher concentrations of bioactive TGF-β<sub>1</sub> and greater upregulation of cartilage-specific gene-expression compared to hMSCs from undiluted-FG. This study showing improved release, transduction efficiency and chondrogenic effect on hMSC of bioactive AAV-TGF-β<sub>1</sub> released from dilute-FG provides information important to optimization of this clinically available scaffold for therapeutic gene-delivery, both in cartilage regeneration and for other tissue-engineering applications. PMID: 21449684 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Responsive Microgrooves for the Formation of Harvestable Tissue Constructs. Langmuir. 2011 Mar 30; Authors: Tekin H, Ozaydin-Ince G, Tsinman T, Gleason KK, Langer R, Khademhosseini A, Demirel MC Given its biocompatibility, elasticity, and gas permeability, poly(dimethylsiloxane) (PDMS) is widely used to fabricate microgrooves and microfluidic devices for three-dimensional (3D) cell culture studies. However, conformal coating of complex PDMS devices prepared by standard microfabrication techniques with desired chemical functionality is challenging. This study describes the conformal coating of PDMS microgrooves with poly(N-isopropylacrylamide) (PNIPAAm) by using initiated chemical vapor deposition (iCVD). These microgrooves guided the formation of tissue constructs from NIH-3T3 fibroblasts that could be retrieved by the temperature-dependent swelling property and hydrophilicity change of the PNIPAAm. The thickness of swollen PNIPAAm films at 24 °C was approximately 3 times greater than at 37 °C. Furthermore, PNIPAAm-coated microgroove surfaces exhibit increased hydrophilicity at 24 °C (contact angle θ = 30° ± 2) compared to 37 °C (θ = 50° ± 1). Thus PNIPAAm film on the microgrooves exhibits responsive swelling with higher hydrophilicity at room temperature, which could be used to retrieve tissue constructs. The resulting tissue constructs were the same size as the grooves and could be used as modules in tissue fabrication. Given its ability to form and retrieve cell aggregates and its integration with standard microfabrication, PNIPAAm-coated PDMS templates may become useful for 3D cell culture applications in tissue engineering and drug discovery. PMID: 21449596 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of low frequency electromagnetic fields on the chondrogenic differentiation of human mesenchymal stem cells. Bioelectromagnetics. 2011 May;32(4):283-90 Authors: Mayer-Wagner S, Passberger A, Sievers B, Aigner J, Summer B, Schiergens TS, Jansson V, Müller PE Electromagnetic fields (EMF) have been shown to exert beneficial effects on cartilage tissue. Nowadays, differentiated human mesenchymal stem cells (hMSCs) are discussed as an alternative approach for cartilage repair. Therefore, the aim of this study was to examine the impact of EMF on hMSCs during chondrogenic differentiation. HMSCs at cell passages five and six were differentiated in pellet cultures in vitro under the addition of human fibroblast growth factor 2 (FGF-2) and human transforming growth factor-β(3) (TGF-β(3) ). Cultures were exposed to homogeneous sinusoidal extremely low-frequency magnetic fields (5 mT) produced by a solenoid or were kept in a control system. After 3 weeks of culture, chondrogenesis was assessed by toluidine blue and safranin-O staining, immunohistochemistry, quantitative real-time polymerase chain reaction (PCR) for cartilage-specific proteins, and a DMMB dye-binding assay for glycosaminoglycans. Under EMF, hMSCs showed a significant increase in collagen type II expression at passage 6. Aggrecan and SOX9 expression did not change significantly after EMF exposure. Collagen type X expression decreased under electromagnetic stimulation. Pellet cultures at passage 5 that had been treated with EMF provided a higher glycosaminoglycan (GAG)/DNA content than cultures that had not been exposed to EMF. Chondrogenic differentiation of hMSCs may be improved by EMF regarding collagen type II expression and GAG content of cultures. EMF might be a way to stimulate and maintain chondrogenesis of hMSCs and, therefore, provide a new step in regenerative medicine regarding tissue engineering of cartilage. Bioelectromagnetics 32:283-290, 2011. © 2010 Wiley-Liss, Inc. PMID: 21452358 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Preparation and characterization of poly(vinyl alcohol)/poly(epsilon-caprolactone)-poly(ethylene glycol)-poly(epsilon-caprolactone)/nano-hydroxyapatite composite membranes for tissue engineering. J Nanosci Nanotechnol. 2011 Mar;11(3):2354-60 Authors: Peng J, Li X, Guo G, Yi T, Fu S, Liang H, Luo F, Zhao X, Wei Y, Qian Z In this paper, the poly(vinyl alcohol)/poly(epsilon-caprolactone)-PEG-poly(epsilon-caprolactone)/nano-hydroxyapatite (PVA/PCEC/n-HA) composite membranes were prepared by solution casting and evaporation methods. The effect of n-HA content on the properties of the composite membranes was studied. The PVA/PCEC/n-HA composite membranes were analyzed by FTIR spectroscopy, X-ray diffraction, water content measurement, contact angle, mechanical test, scanning electron microscopy. The results showed that the surface roughness of the composite membranes increased with the increase of n-HA contents. The n-HA content had obvious influence on the swelling ratio, tensile strength and elongation rate of the composite membranes. With the increase of n-HA contents, the swelling ratio increased at first, and then decreased; tensile strength and elongation rate decreased gradually. The PVA/PCEC/n-HA composite membranes may be applied in the field of tissue engineering. PMID: 21449393 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Nanoscale tissue engineering: spatial control over cell-materials interactions. Nanotechnology. 2011 May 27;22(21):212001 Authors: Wheeldon I, Farhadi A, Bick AG, Jabbari E, Khademhosseini A Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness these interactions through nanoscale biomaterials engineering in order to study and direct cellular behavior. Here, we review two- and three-dimensional (2- and 3D) nanoscale tissue engineering technologies, and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffold technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D. However, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and that can control the temporal changes in the cellular microenvironment. PMID: 21451238 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | [Stem cells for osteoarticular and vascular tissue engineering.] Med Sci (Paris). 2011 Mar;27(3):289-296 Authors: Vinatier C, Bordenave L, Guicheux J, Amédée J Tissue damages or loss of organs often result in structural and metabolic changes that can cause serious complications. The therapeutic objective of tissue engineering (TE) is to recreate, regenerate or restore function of damaged tissue. TE is based on the coalescence of three components: a scaffold or matrix from natural or synthetic origin biodegradable or not, reparative cells and signals (hypoxia, mechanical stress, morphogens…). Articular cartilage, bone and blood vessels are tissues for which TE has progressed significantly, from basic research to clinical trials. If biomaterials must exhibit different properties depending on the tissue to regenerate, the cellular component of TE is mostly represented by stem cells notably adult mesenchymal stem cells harvested from bone marrow or adipose tissue. In recent years, progress has been made in our understanding of the biological mechanisms that govern stem cell differentiation and in the development of materials with controlled physicochemical and biological properties. However, many technological barriers and regulations concerns have to be overcome before tissue engineering enters into the therapeutic arsenal of regenerative medicine. This review aims at highlighting the progress in the use of stem cells for engineering osteoarticular and vascular tissues. PMID: 21447302 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human pluripotent stem cells: decoding the naive state. Sci Transl Med. 2011 Mar 30;3(76):76ps10 Authors: Li W, Ding S Human pluripotent stem cells play a central role in regenerative medicine and tissue engineering. These versatile cells can exist in a range of manipulable states with distinct functionalities, from the late epiblast stage represented by the conventional human embryonic stem cells (hESCs) to the mouse ESC-like naïve state. These functional states must be fully characterized if we are to harness the power of pluripotent stem cells to transform clinical medicine and therapeutics discovery. PMID: 21451122 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Stem Cells For Ocular Tissue Engineering and Regeneration. Curr Top Med Chem. 2011 Mar 30; Authors: Pillai RG With advances in stem cell biology, tissue engineering is becoming increasingly powerful for tissue regeneration. Stem cells with capacity of multilineage and self-renewal are an ideal cell source for tissue engineering. This review focus on discussing the potential strategies including stem cell sources, bio-scaffolds, mechanical stimulation, genetic modification and co-culture techniques to direct ocular-lineage differentiation of stem cells for complete or partial eye regeneration and research. Attempts to use embryonic and somatic stem cells as seed cells for ocular tissue engineering have achieved encouraging results. The combination of chemical and physical signals in stem cell microenvironment could be regulated to induce differentiation of the embryonic stem cells into ocular tissue. This paper present here a broad introduction to the stem cell mediated correction of eye ailments and provide extensive references for the interested reader. This paper also looks into the different aspects of using stem cells for drug development for treating eye ailments. PMID: 21446913 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Spheroid Formation and Expression of Liver-Specific Functions of Human Hepatocellular Carcinoma-Derived FLC-4 Cells Cultured in Lactose-Silk Fibroin Conjugate Sponges. Biomacromolecules. 2011 Mar 30; Authors: Gotoh Y, Ishizuka Y, Matsuura T, Niimi S This study presents a hepatic tissue engineering application of three-dimensional (3D) porous sponges composed of lactose-silk fibroin (SF) conjugates (Lac-CY-SF) bearing β-galactose residues, hepatocyte-specific ligands. Lac-CY-SF sponges were prepared by freeze-drying, followed by immersion in a series of methanol aqueous solutions. Lac-CY-SF sponges showed heterogeneous pore structure with round pores about 100 μm in diameter and elongated pores 250-450 μm in length and 100-150 μm in breadth. To employ a 3D Lac-CY-SF culture system, human hepatocellular carcinoma-derived FLC-4 cells were seeded in Lac-CY-SF sponges and cultured up to 3 weeks. FLC-4 cell culture in collagen and SF sponges was also performed for comparison with the cell response to Lac-CY-SF sponges. Within 5 days of culture, FLC-4 cells cultured in Lac-CY-SF sponges, as well as the cells cultured in collagen sponges, formed multicellular spheroids with diameters from 30 to 100 μm more efficiently than did the cells cultured in SF sponges. After 3 weeks of culture, WST-1 viability assay revealed that shrinkage suppression of Lac-CY-SF sponges enabled the maintenance of viable FLC-4 cells for a long time, while the shrinkage and disintegration of collagen sponges prevented the maintenance of the cells. FLC-4 cells cultured in Lac-CY-SF sponges exhibited greater elevation of albumin secretion and sustained a higher albumin level compared with the cells cultured in collagen and SF sponges during the 3 week cultivation period. FLC-4 cells cultured in Lac-CY-SF sponges for 3 weeks expressed genes related to liver-specific functions such as transferrin and HNF-4α. On the other hand, the cells cultured in collagen and SF sponges for 3 weeks did not express these genes. These results indicated the very promising properties of Lac-CY-SF sponges as a scaffold for long-term culture of functional FLC-4 cells to study drug toxicity and hepatocyte metabolism in humans and develop a bioartificial liver model. PMID: 21449575 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Optimizing the medium perfusion rate in bone tissue engineering bioreactors. Biotechnol Bioeng. 2011 May;108(5):1159-70 Authors: Grayson WL, Marolt D, Bhumiratana S, Fröhlich M, Guo XE, Vunjak-Novakovic G There is a critical need to increase the size of bone grafts that can be cultured in vitro for use in regenerative medicine. Perfusion bioreactors have been used to improve the nutrient and gas transfer capabilities and reduce the size limitations inherent to static culture, as well as to modulate cellular responses by hydrodynamic shear. Our aim was to understand the effects of medium flow velocity on cellular phenotype and the formation of bone-like tissues in three-dimensional engineered constructs. We utilized custom-designed perfusion bioreactors to culture bone constructs for 5 weeks using a wide range of superficial flow velocities (80, 400, 800, 1,200, and 1,800 µm/s), corresponding to estimated initial shear stresses ranging from 0.6 to 20 mPa. Increasing the flow velocity significantly affected cell morphology, cell-cell interactions, matrix production and composition, and the expression of osteogenic genes. Within the range studied, the flow velocities ranging from 400 to 800 µm/s yielded the best overall osteogenic responses. Using mathematical models, we determined that even at the lowest flow velocity (80 µm/s) the oxygen provided was sufficient to maintain viability of the cells within the construct. Yet it was clear that this flow velocity did not adequately support the development of bone-like tissue. The complexity of the cellular responses found at different flow velocities underscores the need to use a range of evaluation parameters to determine the quality of engineered bone. Bioeng. 2011; 108:1159-1170. © 2010 Wiley Periodicals, Inc. PMID: 21449028 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Morphological and histological analysis on the in vivo degradation of poly (propylene fumarate)/(calcium sulfate/β-tricalcium phosphate). Biomed Microdevices. 2011 Mar 30; Authors: Cai Z, Zhang T, Di L, Xu DM, Xu DH, Yang DA Poly (propylene fumarate)/(Calcium sulfate/β-tricalcium phosphate) (PPF/(CaSO(4)/β-TCP)) is a kind of biodegradable composite designed for bone tissue engineering. The in vitro degradation behavior of this composite has been investigated in our previous study. The aim of this study was to investigate the effects of PPF molecular weight and CaSO(4)/β-TCP molar ratio on the in vivo degradation of PPF/(CaSO(4)/β-TCP) composite and the bone tissue response to PPF/(CaSO(4)/β-TCP). Total 36 PPF/(CaSO(4)/β-TCP) composite samples were implanted into 15.0 mm segmental defects in tibiae of 18 Japanese rabbits, harvested at 2, 4 and 8 weeks after the operation, and analyzed using radiographic and histological analysis to assess the in vivo degradation of the composites as well as tissue response to the implants. The in vivo degradation results show that all the samples maintained their original shape. Tissues penetrated into the pores which formed by the degradation of CaSO(4)/β-TCP spheres near the surface of the composites. The rate of in vivo degradation and pore forming increased with a decrease in PPF molecular weight and an increase in CaSO(4)/β-TCP molar ratio. No inflammatory reaction was observed after implantation, and the composites are capable of in situ pore forming. In particular, the pore forming rate can be adjusted by varying the composition of the composites. These results may indicate that PPF/(CaSO(4)/β-TCP) is a promising osteogenic scaffold for its controllable degradation rate and excellent biocompatibility. PMID: 21448654 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Artificial Niche Combining Elastomeric Substrate and Platelets Guides Vascular Differentiation of Bone Marrow Mononuclear Cells. Tissue Eng Part A. 2011 Mar 30; Authors: Wu W, Allen RA, Gao J, Wang Y ABSTRACT Bone marrow derived progenitor cells are promising cell sources for vascular tissue engineering. However, conventional bone marrow mesenchymal stem cell (BMSC) expansion and induction strategies require plating on tissue culture plastic, a stiff substrate which may itself influence cell differentiation. Direct scaffold seeding avoids plating on plastic, to the best of our knowledge, there is no report of any scaffold that induces the differentiation of bone marrow mononuclear cells (BMNCs) to vascular cells in vitro. In this study, we hypothesize that an elastomeric scaffold with adsorbed plasma proteins and platelets will induce differentiation of BMNCs to vascular cells and promote vascular tissue formation by combining soft tissue mechanical properties with platelet-mediated tissue repairing signals. To test our hypothesis, we directly seeded rat primary BMNCs in 4 types of scaffolds: poly(lactide-co-glycolide) (PLGA), elastomeric poly(glycerol sebacate) (PGS), platelet-poor plasma coated PGS (P-PGS), PGS coated by plasma supplemented with platelets (Pl-P-PGS). After 21 days of culture, osteochondral differentiation of cells in PLGA was detected but most of the adhered cells on the surface of all PGS scaffolds expressed calponin-Ⅰand α-smooth muscle actin (α-SMA), suggesting smooth muscle differentiation. Cells in PGS scaffolds also produced significant amount of collagen and elastin. Furthermore, plasma coating improves seeding efficiency, and platelet increases proliferation, the number of differentiated cells, and extracellular matrix (ECM) content. Thus the artificial niche composed of platelets, plasma and PGS is promising for artery tissue engineering using BMNCs. PMID: 21449713 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Can Microcarrier Expanded Chondrocytes Synthesize Cartilaginous Tissue In Vitro? Tissue Eng Part A. 2011 Mar 30; Authors: Surrao DC, Khan AA, McGregor AJ, Amsden BG, Waldman SD Tissue engineering is a promising approach for articular cartilage repair; however, it is challenging to produce adequate amounts of tissue in vitro from the limited number of cells that can be extracted from an individual. Relatively few cell expansion methods exist without the problems of de-differentiation and/or loss of potency. Recently however, several studies have noted the benefits of three dimensional (3D) over monolayer expansion, but the ability of 3D expanded chondrocytes to synthesize cartilaginous tissue constructs has not been demonstrated. Thus, the purpose of this study was to compare the properties of engineered cartilage constructs from expanded cells (monolayer and 3D microcarriers) to those developed from primary chondrocytes. Isolated bovine chondrocytes were grown for three weeks in either monolayer (T-Flasks) or 3D microcarrier (Cytodex 3) expansion culture. Expanded and isolated primary cells were then seeded in high density culture on Millicell™ filters for a period of four weeks to evaluate the ability to synthesize cartilaginous tissue. While microcarrier expansion was twice as effective as monolayer expansion (microcarrier: 110-fold increase, monolayer: 52-fold increase), the expanded cells (monolayer and 3D microcarrier) were not effectively able to synthesize cartilaginous tissue in vitro. Tissues developed from primary cells were substantially thicker and accumulated significantly more extracellular matrix (proteoglycan content: 156-292% increase; collagen content: 70-191% increase). These results were attributed to phenotypic changes experienced during the expansion phase. Monolayer expanded chondrocytes lost their native morphology within one week whereas microcarrier expanded cells were spreading by three weeks of expansion. While the use of 3D microcarriers can lead to large cellular yields, preservation of chondrogenic phenotype during expansion is required in order to synthesize cartilaginous tissue. PMID: 21449621 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In vivo tissue engineering of functional skeletal muscle by freshly isolated satellite cells embedded in a photopolymerizable hydrogel. FASEB J. 2011 Mar 30; Authors: Rossi CA, Flaibani M, Blaauw B, Pozzobon M, Figallo E, Reggiani C, Vitiello L, Elvassore N, De Coppi P The success of skeletal muscle reconstruction depends on finding the most effective, clinically suitable strategy to engineer myogenic cells and biocompatible scaffolds. Satellite cells (SCs), freshly isolated or transplanted within their niche, are presently considered the best source for muscle regeneration. Here, we designed and developed the delivery of either SCs or muscle progenitor cells (MPCs) via an in situ photo-cross-linkable hyaluronan-based hydrogel, hyaluronic acid-photoinitiator (HA-PI) complex. Partially ablated tibialis anterior (TA) of C57BL/6J mice engrafted with freshly isolated satellite cells embedded in hydrogel showed a major improvement in muscle structure and number of new myofibers, compared to muscles receiving hydrogel + MPCs or hydrogel alone. Notably, SCs embedded in HA-PI also promoted functional recovery, as assessed by contractile force measurements. Tissue reconstruction was associated with the formation of both neural and vascular networks and the reconstitution of a functional SC niche. This innovative approach could overcome previous limitations in skeletal muscle tissue engineering.-Rossi, C. A., Flaibani, M., Blaauw, B., Pozzobon, M., Figallo, E., Reggiani, C., Vitiello, L., Elvassore, N., De Coppi, P. In vivo tissue engineering of functional skeletal muscle by freshly isolated satellite cells embedded in a photopolymerizable hydrogel. PMID: 21450908 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Application of an Endothelialized Modular Construct for Islet Transplantation in Syngeneic and Allogeneic Immunesuppressed Rat Models. Tissue Eng Part A. 2011 Mar 30; Authors: Gupta R, Sefton MV Modular tissue engineering is a novel approach to assemble tissues with an inherent vascularization. In this paper, we evaluated whether endothelialized module driven vascularization enhances islet engraftment in diabetic rats. Two thousand islets were transplanted in the omental pouch of syngeneic and allogeneic immunesuppressed diabetic recipients either as free islets, islets in collagen modules or islets in endothelialized modules. Transplantation of islets in endothelialized modules significantly increased the vessel density compared to controls. Donor GFP positive endothelial cells (EC) formed vessels in close proximity to transplanted islets; donor vessels connected to host vasculature as the vessels included erythrocytes in their lumens and were supported by host smooth muscle cells by 21 days. Transplantation of 2000 islets reversed diabetes in 2 of 5 of syngeneic recipients until 60 days, although there was no apparent benefit to islet function of adding endothelial cells relative to collagen modules without EC. However, there was a trend towards increased viability when islets were implanted in endothelialized modules compared to collagen modules at 21 days. Meanwhile, 2000 islets in allogeneic immunesuppressed recipients lowered blood glucose levels short term but there was graft failure within one week. This study explored the simultaneous transplantation of primary endothelial cells with islets in diabetic recipients. The endothelialized modular approach increased vessel density around transplanted islets. Further modulation (i.e. acceleration) of vessel maturation, is presumed necessary to improve islet engraftment. PMID: 21449709 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Extracorporeal shock wave-induced proliferation of periosteal cells. J Orthop Res. 2011 Mar 29; Authors: Kearney CJ, Lee JY, Padera RF, Hsu HP, Spector M PMID: 21448986 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biomimetic coating of organic polymers with a protein-functionalized layer of calcium phosphate: the surface properties of the carrier influence neither the coating characteristics nor the incorporation mechanism or release kinetics of the protein. Tissue Eng Part C Methods. 2010 Dec;16(6):1255-65 Authors: Wu G, Liu Y, Iizuka T, Hunziker EB Polymers that are used in clinical practice as bone-defect-filling materials possess many essential qualities, such as moldability, mechanical strength and biodegradability, but they are neither osteoconductive nor osteoinductive. Osteoconductivity can be conferred by coating the material with a layer of calcium phosphate, which can be rendered osteoinductive by functionalizing it with an osteogenic agent. We wished to ascertain whether the morphological and physicochemical characteristics of unfunctionalized and bovine-serum-albumin (BSA)-functionalized calcium-phosphate coatings were influenced by the surface properties of polymeric carriers. The release kinetics of the protein were also investigated. Two sponge-like materials (Helistat® and Polyactive®) and two fibrous ones (Ethisorb™ and poly[lactic-co-glycolic acid]) were tested. The coating characteristics were evaluated using state-of-the-art methodologies. The release kinetics of BSA were monitored spectrophotometrically. The characteristics of the amorphous and the crystalline phases of the coatings were not influenced by either the surface chemistry or the surface geometry of the underlying polymer. The mechanism whereby BSA was incorporated into the crystalline layer and the rate of release of the truly incorporated depot were likewise unaffected by the nature of the polymeric carrier. Our biomimetic coating technique could be applied to either spongy or fibrous bone-defect-filling organic polymers, with a view to rendering them osteoconductive and osteoinductive. PMID: 20196638 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Artificial Niche Combining Elastomeric Substrate and Platelets Guides Vascular Differentiation of Bone Marrow Mononuclear Cells. Tissue Eng Part A. 2011 Mar 30; Authors: Wu W, Allen RA, Gao J, Wang Y ABSTRACT Bone marrow derived progenitor cells are promising cell sources for vascular tissue engineering. However, conventional bone marrow mesenchymal stem cell (BMSC) expansion and induction strategies require plating on tissue culture plastic, a stiff substrate which may itself influence cell differentiation. Direct scaffold seeding avoids plating on plastic, to the best of our knowledge, there is no report of any scaffold that induces the differentiation of bone marrow mononuclear cells (BMNCs) to vascular cells in vitro. In this study, we hypothesize that an elastomeric scaffold with adsorbed plasma proteins and platelets will induce differentiation of BMNCs to vascular cells and promote vascular tissue formation by combining soft tissue mechanical properties with platelet-mediated tissue repairing signals. To test our hypothesis, we directly seeded rat primary BMNCs in 4 types of scaffolds: poly(lactide-co-glycolide) (PLGA), elastomeric poly(glycerol sebacate) (PGS), platelet-poor plasma coated PGS (P-PGS), PGS coated by plasma supplemented with platelets (Pl-P-PGS). After 21 days of culture, osteochondral differentiation of cells in PLGA was detected but most of the adhered cells on the surface of all PGS scaffolds expressed calponin-Ⅰand α-smooth muscle actin (α-SMA), suggesting smooth muscle differentiation. Cells in PGS scaffolds also produced significant amount of collagen and elastin. Furthermore, plasma coating improves seeding efficiency, and platelet increases proliferation, the number of differentiated cells, and extracellular matrix (ECM) content. Thus the artificial niche composed of platelets, plasma and PGS is promising for artery tissue engineering using BMNCs. PMID: 21449713 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of low frequency electromagnetic fields on the chondrogenic differentiation of human mesenchymal stem cells. Bioelectromagnetics. 2011 May;32(4):283-90 Authors: Mayer-Wagner S, Passberger A, Sievers B, Aigner J, Summer B, Schiergens TS, Jansson V, Müller PE Electromagnetic fields (EMF) have been shown to exert beneficial effects on cartilage tissue. Nowadays, differentiated human mesenchymal stem cells (hMSCs) are discussed as an alternative approach for cartilage repair. Therefore, the aim of this study was to examine the impact of EMF on hMSCs during chondrogenic differentiation. HMSCs at cell passages five and six were differentiated in pellet cultures in vitro under the addition of human fibroblast growth factor 2 (FGF-2) and human transforming growth factor-β(3) (TGF-β(3) ). Cultures were exposed to homogeneous sinusoidal extremely low-frequency magnetic fields (5 mT) produced by a solenoid or were kept in a control system. After 3 weeks of culture, chondrogenesis was assessed by toluidine blue and safranin-O staining, immunohistochemistry, quantitative real-time polymerase chain reaction (PCR) for cartilage-specific proteins, and a DMMB dye-binding assay for glycosaminoglycans. Under EMF, hMSCs showed a significant increase in collagen type II expression at passage 6. Aggrecan and SOX9 expression did not change significantly after EMF exposure. Collagen type X expression decreased under electromagnetic stimulation. Pellet cultures at passage 5 that had been treated with EMF provided a higher glycosaminoglycan (GAG)/DNA content than cultures that had not been exposed to EMF. Chondrogenic differentiation of hMSCs may be improved by EMF regarding collagen type II expression and GAG content of cultures. EMF might be a way to stimulate and maintain chondrogenesis of hMSCs and, therefore, provide a new step in regenerative medicine regarding tissue engineering of cartilage. Bioelectromagnetics 32:283-290, 2011. © 2010 Wiley-Liss, Inc. PMID: 21452358 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Long term culture of mesenchymal stem cells in hypoxia promotes a genetic program maintaining their undifferentiated and multipotent status. BMC Cell Biol. 2011 Mar 30;12(1):12 Authors: Basciano L, Nemos C, Foliguet B, de Isla N, de Carvalho M, Tran N, Dalloul A ABSTRACT: BACKGROUND: In the bone marrow, hematopietic and mesenchymal stem cells form a unique niche in which the oxygen tension is low. Hypoxia may have a role in maintaining stem cell fate, self renewal and multipotency. However, whereas most studies addressed the effect of transient in vitro exposure of MSC to hypoxia, permanent culture under hypoxia should reflect the better physiological conditions. RESULTS: Morphologic studies, differentiation and transcriptional profiling experiments were performed on MSC cultured in normoxia (21% O2) versus hypoxia (5% O2) for up to passage 2. Cells at passage 0 and at passage 2 were compared, and those at P0 in hypoxia generated fewer and smaller colonies than in normoxia. In parallel, MSC displayed (>4 fold) inhibition of genes involved in DNA metabolism, cell cycle progression and chromosome cohesion whereas transcripts involved in adhesion and metabolism (CD93, ESAM, VWF, PLVAP, ANGPT2, LEP, TCF1) were stimulated. Compared to normoxic cells, hypoxic cells were morphologically undifferentiated and contained less mitochondrias. After this lag phase, cells at passage 2 in hypoxia outgrew the cells cultured in normoxia and displayed an enhanced expression of genes (4-60 fold) involved in extracellular matrix assembly (SMOC2), neural and muscle development (NOG, GPR56, SNTG2, LAMA) and epithelial development (DMKN). This group described herein for the first time was assigned by the Gene Ontology program to "plasticity". CONCLUSION: The duration of hypoxemia is a critical parameter in the differentiation capacity of MSC. Even in growth promoting conditions, hypoxia enhanced a genetic program that maintained the cells undifferentiated and multipotent. This condition may better reflect the in vivo gene signature of MSC, with potential implications in regenerative medicine. PMID: 21450070 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem cell stratagems in alternative medicine. Regen Med. 2011 Mar 31; Authors: Sipp D Stem cell research has attracted an extraordinary amount of attention and expectation due to its potential for applications in the treatment of numerous medical conditions. These exciting clinical prospects have generated widespread support from both the public and private sectors, and numerous preclinical studies and rigorous clinical trials have already been initiated. Recent years, however, have also seen alarming growth in the number and variety of claims of clinical uses of notional 'stem cells' that have not been adequately tested for safety and/or efficacy. In this article, I will survey the contours of the stem cell industry as practiced by alternative medicine providers, and highlight points of commonality in their strategies for marketing. PMID: 21449827 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Effects of miR-541 on neurite outgrowth during neuronal differentiation. Cell Biochem Funct. 2011 Mar 31; Authors: Zhang J, Zhang J, Liu LH, Zhou Y, Li YP, Shao ZH, Wu YJ, Li MJ, Fan YY, Shi HJ MicroRNA (miRNAs) are short non-coding RNA molecules that downregulate gene expression at post-transcriptional level. miRNAs are post-transcriptional regulators of gene expression important for neuron development and function. This report demonstrated that a putative and chemically synthesized miRNA rno-mir-541 played an important role in the neuron development. Differentiation of PC12 cells with nerve growth factor (NGF) is associated with neurite outgrowth, a process that involves upregulation of Synapsin I. We predicted, detected and assessed the expression levels of a number of possible miRNAs for synapsin I in rats and our outcomes showed that rno-mir-541 was associated with rat synapsin I expression. miR-541, a brain specific miRNA, plays an important role in repressing neurite extension in cultured PC12 neurons. The neurites of PC12 cells was shortened drasticly as a result of the overexpression of rno-mir-541. In contrast, the neurites of PC12 cell developed well after the knockdown of rno-mir-541 by RNA interference. Our study showed that rno-mir-541 played an important role in neuron-cell proliferation and neurite outgrowth through suppressing the expression of its target gene synapsin I. Furthermore, the introduction of NGF causes downregulation of miR-541, de-repression of its target, Synapsin-I and allows for neuritogenesis. Thus, miR-541 functions in neuronal precursors as an endogenous conditional component between NGF and Synapsin-I. Copyright © 2011 John Wiley & Sons, Ltd. PMID: 21452340 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human pluripotent stem cells: decoding the naive state. Sci Transl Med. 2011 Mar 30;3(76):76ps10 Authors: Li W, Ding S Human pluripotent stem cells play a central role in regenerative medicine and tissue engineering. These versatile cells can exist in a range of manipulable states with distinct functionalities, from the late epiblast stage represented by the conventional human embryonic stem cells (hESCs) to the mouse ESC-like naïve state. These functional states must be fully characterized if we are to harness the power of pluripotent stem cells to transform clinical medicine and therapeutics discovery. PMID: 21451122 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Stem cells for neural regeneration - a potential application of very small embryonic-like stem cells. J Physiol Pharmacol. 2011 Feb;62(1):3-12 Authors: Ratajczak J, Zuba-Surma E, Paczkowska E, Kucia M, Nowacki P, Ratajczak MZ The goal of regenerative medicine is to ameliorate irreversible destruction of brain tissue by harnessing the power of stem cells in the process of neurogenesis. Several types of stem cells, including mesenchymal stem cells, hematopoietic stem cells, as well as neural cells differentiated from embryonic stem cell lines, have been proposed as potential therapeutic vehicles. In this review paper we will discuss a perspective of stem cell therapies for neurological disorders with special emphasis on potential application of cells isolated from adult tissues. In support of this our group found that murine bone marrow contains a mobile population of Oct-4(+)CXCR4(+)SSEA-1(+)Sca-1(+)lin(-)CD45(-) very small embryonic-like stem cells (VSELs) that are mobilized into peripheral blood in a murine stroke model. The number of these cells in circulation increases also after pharmacological mobilization by administration of granulocyte colony stimulating factor (G-CSF). Recently we found that VSELs are present in various non-hematopoietic adult organs and, interestingly, our data indicate that the brain contains a high number of cells that display the VSEL phenotype. Based on our published data both in human and mice we postulate that VSELs are a mobile population of epiblast/germ line-derived stem cells and play an important role as an organ-residing reserve population of pluripotent stem cells that give rise to stem cells committed to particular organs and tissues - including neural tissue. In conclusion human VSELs could be potentially harnessed in regenerative medicine as a source of stem cells for neurogenesis. PMID: 21451204 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | IBD: Stem cell therapy feasible, safe and beneficial for fistulizing Crohn's disease. Nat Rev Gastroenterol Hepatol. 2011 Mar 1; Authors: Wood NJ PMID: 21451483 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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