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| Correction
July 22, 2010 at 9:01 PM
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| | In two recent items, we misspelled the last name of a Duke University researcher. The correct spelling is Rob Wechsler-Reya. We had it incorrectly as Weschler. | | |
| Questions and Commentary on Stem Cell Reprogramming
July 22, 2010 at 11:45 AM
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| The California stem cell agency and a UC Davis stem cell researcher are blogging on the implications of research that indicates that reprogrammed adult stem cells may not be the magic bullet that avoids the problems associated with human embryonic stem cells.
You can find a summary of some of the research and discussion from CIRM's Amy Adams here. Paul Knoepfler of UC Davis said,
"So if iPS | | |
| Adipose tissue-derived stem cells rescue Purkinje neurons and alleviate inflammatory responses in Niemann-Pick disease type C mice.
July 22, 2010 at 6:59 AM
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| | Adipose tissue-derived stem cells rescue Purkinje neurons and alleviate inflammatory responses in Niemann-Pick disease type C mice. Cell Tissue Res. 2010 May;340(2):357-69 Authors: Bae JS, Carter JE, Jin HK Adult stem cells offer special therapeutic prospects because they can be isolated for autologous transplantation, expanded ex vivo, and differentiated into various cell types. We previously reported that bone marrow-derived mesenchymal stem cells improve neurological deficits in neurodegenerative disease animal models. However, the efficacy of adipose tissue-derived stem cells (ADSCs) transplantation in similar models remains unknown. Herein, we demonstrate that ADSCs, when transplanted into Niemann-Pick disease type C (NP-C) mouse cerebellum, elicit rescue of Purkinje neurons and restoration of motor coordination together with alleviation of inflammatory responses as verified by immunohistochemistry and real-time PCR using glial fibrillary acidic protein (GFAP), F4/80, IL-1 beta, IL-6, and TNF-alpha. Most importantly, ADSCs enhance electrically active Purkinje neurons with functional synaptic formation after transplantation in NP-C disease model mice. This report demonstrates for the first time that ADSCs can rescue imperiled Purkinje neurons and alleviate the inflammatory response in NP-C disease model mice, thereby signifying the therapeutic potential of ADSCs for neurodegenerative diseases. PMID: 20238127 [PubMed - indexed for MEDLINE] | | |
| Genipin-cross-linked collagen/chitosan biomimetic scaffolds for articular cartilage tissue engineering applications.
July 22, 2010 at 6:46 AM
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| | Genipin-cross-linked collagen/chitosan biomimetic scaffolds for articular cartilage tissue engineering applications. J Biomed Mater Res A. 2010 Jul 20; Authors: Yan LP, Wang YJ, Ren L, Wu G, Caridade SG, Fan JB, Wang LY, Ji PH, Oliveira JM, Oliveira JT, Mano JF, Reis RL In this study, genipin-cross-linked collagen/chitosan biodegradable porous scaffolds were prepared for articular cartilage regeneration. The influence of chitosan amount and genipin concentration on the scaffolds physicochemical properties was evaluated. The morphologies of the scaffolds were characterized by scanning electron microscope (SEM) and cross-linking degree was investigated by ninhydrin assay. Additionally, the mechanical properties of the scaffolds were assessed under dynamic compression. To study the swelling ratio and the biostability of the collagen/chitosan scaffold, in vitro tests were also carried out by immersion of the scaffolds in PBS solution or digestion in collagenase, respectively. The results showed that the morphologies of the scaffolds underwent a fiber-like to a sheet-like structural transition by increasing chitosan amount. Genipin cross-linking remarkably changed the morphologies and pore sizes of the scaffolds when chitosan amount was less than 25%. Either by increasing the chitosan ratio or performing cross-linking treatment, the swelling ratio of the scaffolds can be tailored. The ninhydrin assay demonstrated that the addition of chitosan could obviously increase the cross-linking efficiency. The degradation studies indicated that genipin cross-linking can effectively enhance the biostability of the scaffolds. The biocompatibility of the scaffolds was evaluated by culturing rabbit chondrocytes in vitro. This study demonstrated that a good viability of the chondrocytes seeded on the scaffold was achieved. The SEM analysis has revealed that the chondrocytes adhered well to the surface of the scaffolds and contacted each other. These results suggest that the genipin-cross-linked collagen/chitosan matrix may be a promising formulation for articular cartilage scaffolding. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A: , 2010. PMID: 20648541 [PubMed - as supplied by publisher] | | |
| Plastic compression of a collagen gel forms a much improved scaffold for ocular surface tissue engineering over conventional collagen gels.
July 22, 2010 at 6:46 AM
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| | Plastic compression of a collagen gel forms a much improved scaffold for ocular surface tissue engineering over conventional collagen gels. J Biomed Mater Res A. 2010 Jul 20; Authors: Mi S, Chen B, Wright B, Connon CJ We compare the use of plastically compressed collagen gels to conventional collagen gels as scaffolds onto which corneal limbal epithelial cells (LECs) are seeded to construct an artificial corneal epithelium. LECs were isolated from bovine corneas (limbus) and seeded onto either conventional uncompressed or novel compressed collagen gels and grown in culture. Scanning electron microscopy (SEM) results showed that fibers within the uncompressed gel were loose and irregularly ordered, whereas the fibers within the compressed gel were densely packed and more evenly arranged. Quantitative analysis of LECs expansion across the surface of the two gels showed similar growth rates (p > 0.05). Under SEM, the LECs, expanded on uncompressed gels, showed a rough and heterogeneous morphology, whereas on the compressed gel, the cells displayed a smooth and homogeneous morphology. Transmission electron microscopy (TEM) results showed the compressed scaffold to contain collagen fibers of regular diameter and similar orientation resembling collagen fibers within the normal cornea. TEM and light microscopy also showed that cell-cell and cell-matrix attachment, stratification, and cell density were superior in LECs expanded upon compressed collagen gels. This study demonstrated that the compressed collagen gel was an excellent biomaterial scaffold highly suited to the construction of an artificial corneal epithelium and a significant improvement upon conventional collagen gels. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20648540 [PubMed - as supplied by publisher] | | |
| Effective seeding of smooth muscle cells into tubular poly(trimethylene carbonate) scaffolds for vascular tissue engineering.
July 22, 2010 at 6:46 AM
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| | Effective seeding of smooth muscle cells into tubular poly(trimethylene carbonate) scaffolds for vascular tissue engineering. J Biomed Mater Res A. 2010 Jul 20; Authors: Song Y, Wennink JW, Kamphuis MM, Vermes I, Poot AA, Feijen J, Grijpma DW Porous tubular poly(trimethylene carbonate) (PTMC) scaffolds for vascular tissue engineering, with an inner diameter of 3 mm and a wall thickness of 1 mm, were prepared by means of dip-coating and subsequent leaching of NaCl particles. The scaffolds, with an average pore size of 110 mum and a porosity of 85%, showed a smooth muscle cell (SMC) seeding efficiency of only 10%. To increase the efficiency of cell seeding, these scaffolds were coated with a microporous PTMC outer layer with a thickness of 0.1-0.4 mm, an average pore size of 28 mum, and a porosity of 65%. Coating of the scaffolds with the microporous outer layer did not influence the inner pore structure or the mechanical properties of the scaffolds to a significant extent. The intrinsic permeability of the scaffolds decreased from 60 x 10(-10) m(2) to approximately 5 x 10(-10) m(2) after coating with the microporous outer layer. The latter value is still relatively high indicating that these scaffolds may facilitate sufficient diffusion of nutrients and waste products during cell culturing. The efficiency of SMC seeding determined after 24 h cell adhesion in the scaffolds increased from less than 10% to 43% after coating with the microporous outer layer. The cells were homogeneously distributed in the scaffolds and cell numbers increased 60% during culturing for 7 days under stationary conditions. It is concluded that coating of porous tubular PTMC scaffolds with a microporous PTMC outer layer facilitates effective cell seeding in these scaffolds. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20648539 [PubMed - as supplied by publisher] | | |
| Functional assay, expression of growth factors and proteins modulating bone-arrangement in human osteoblasts seeded on an anorganic bovine bone biomaterial.
July 22, 2010 at 6:46 AM
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| | Functional assay, expression of growth factors and proteins modulating bone-arrangement in human osteoblasts seeded on an anorganic bovine bone biomaterial. Eur Cell Mater. 2010;20:72-83 Authors: Trubiani O, Fulle S, Traini T, Paludi M, la Rovere R, Orciani M, Caputi S, Piattelli A The basic aspects of bone tissue engineering include chemical composition and geometry of the scaffold design, because it is very important to improve not only cell attachment and growth but especially osteodifferentiation, bone tissue formation, and vascularization. Geistlich Bio-Oss(R) (GBO) is a xenograft consisting of deproteinized, sterilized bovine bone, chemically and physically identical to the mineral phase of human bone. In this study, we investigated the growth behaviour and the ability to form focal adhesions on the substrate, using vinculin, a cytoskeletal protein, as a marker. Moreover, the expression of bone specific proteins and growth factors such as type I collagen, osteopontin, bone sialoprotein, bone morphogenetic protein-2 (BMP-2), BMP-7 and de novo synthesis of osteocalcin in normal human osteoblasts (NHOst) seeded on xenogenic GBO were evaluated. Our observations suggest that after four weeks of culture in differentiation medium, the NHOst showed a high affinity for the three dimensional biomaterial; in fact, cellular proliferation, migration and colonization were clearly evident. The osteogenic differentiation process, as demonstrated by morphological, histochemical, energy dispersive X-ray microanalysis and biochemical analysis was mostly obvious in the NHOst grown on three-dimensional inorganic bovine bone biomaterial. Functional studies displayed a clear and significant response to calcitonin when the cells were differentiated. In addition, the presence of the biomaterial improved the response, suggesting that it could drive the differentiation of these cells towards a more differentiated osteogenic phenotype. These results encourage us to consider GBO an adequate biocompatible three-dimensional biomaterial, indicating its potential use for the development of tissue-engineering techniques. PMID: 20648427 [PubMed - in process] | | |
| Electrospun nanofibers for neural tissue engineering.
July 22, 2010 at 6:46 AM
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| | Electrospun nanofibers for neural tissue engineering. Nanoscale. 2010 Jan 8;2(1):35-44 Authors: Xie J, Macewan MR, Schwartz AG, Xia Y Biodegradable nanofibers produced by electrospinning represent a new class of promising scaffolds to support nerve regeneration. We begin with a brief discussion on the electrospinning of nanofibers and methods for controlling the structure, porosity, and alignment of the electrospun nanofibers. The methods include control of the nanoscale morphology and microscale alignment of the nanofibers, as well as the fabrication of macroscale, three-dimensional tubular structures. We then highlight recent studies that utilize electrospun nanofibers to manipulate biological processes relevant to nervous tissue regeneration, including stem cell differentiation, guidance of neurite extension, and peripheral nerve injury treatments. The main objective of this feature article is to provide valuable insights into methods for investigating the mechanisms of neurite growth on novel nanofibrous scaffolds and optimization of the nanofiber scaffolds and conduits for repairing peripheral nerve injuries. PMID: 20648362 [PubMed - as supplied by publisher] | | |
| Comb-type grafted poly(N-isopropylacrylamide) gel modified surfaces for rapid detachment of cell sheet.
July 22, 2010 at 6:46 AM
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| | Comb-type grafted poly(N-isopropylacrylamide) gel modified surfaces for rapid detachment of cell sheet. Biomaterials. 2010 Jul 19; Authors: Tang Z, Akiyama Y, Yamato M, Okano T A comb-type grafted poly(N-isopropylacrylamide) (PIPAAm) gel modified surface was newly developed for providing a rapid cell sheet recovery for tissue engineering. PIPAAm macromonomer was prepared by the etherification reaction of the hydroxyl terminal moieties of PIPAAm with acryloyl chloride, followed by the radical telomerization reaction of N-isopropylacrylamide (IPAAm) monomer using 2-mercaptoethanol as a chain transfer agent. Solution containing IPAAm monomer and PIPAAm macromonomer was spread on the surface of tissue culture polystyrene (TCPS), and then the surface was subjected to electron beam irradiation for grafting the monomer and macromonomer on the surfaces, resulting in comb-type grafted PIPAAm gel modified TCPS (GG-TCPS). Besides the difference of the amount of the modified PIPAAm, no distinct difference was found between the properties of GG-TCPSs and normal-type PIPAAm gel modified TCPS (NG-TCPS) through XPS, AFM and a contact angle measurement. At 37 degrees C, bovine aortic endothelial cells (BAECs) were well adhered and spread on GG-TCPS as well as NG-TCPS regardless of the macromonomer concentration. By lowering temperature to 20 degrees C, BAECs detached themselves more rapidly from GG-TCPS compared with NG-TCPS. Upon lowering temperature, the grafted polymer was speculated to accelerate the hydration of modified PIPAAm gel, resulting in a rapid cell sheet detachment. PMID: 20647153 [PubMed - as supplied by publisher] | | |
| Cell-adhesive and mechanically tunable glucose-based biodegradable hydrogels.
July 22, 2010 at 6:46 AM
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| | Cell-adhesive and mechanically tunable glucose-based biodegradable hydrogels. Acta Biomater. 2010 Jul 17; Authors: Shin H, Nichol JW, Khademhosseini A The development of materials with biomimetic mechanical and biological properties is of great interest for regenerative medicine applications. In particular, hydrogels are a promising class of biomaterials due to their high water content, which mimic that of natural tissues. We have synthesized a hydrophilic biodegradable polymer, designated poly(glucose malate)methacrylate (PGMma), that is composed of glucose and malic acid which are commonly found in the human metabolic system. This polymer is made photocrosslinkable by the incorporation of methacrylate groups. The resulting properties of the hydrogels can be tuned by altering the reacting ratio of the starting materials, the degree of methacrylation, and the polymer concentration of the resultant hydrogel. Hydrogels exhibited compressive moduli ranging from 1.8 +/- 0.4kPa to 172.7 +/- 36kPa with compressive strain at failure from 37.5 +/- 0.9% to 61.2 +/- 1.1%, and hydration by mass ranging from 18.7 +/- 0.5% to 114.1 +/- 1.3%. PGMma hydrogels also showed a broad range of degradation rates and were cell-adhesive, enabling the spreading of adherent cells. Overall, this work introduces a class of cell adhesive, mechanically tunable and biodegradable glucose-based hydrogels that may be useful for various tissue engineering and cell culture applications. PMID: 20647064 [PubMed - as supplied by publisher] | | |
| [L'ingegnerizzazione tissutale delle cellule paratiroidee.]
July 22, 2010 at 6:46 AM
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| | [L'ingegnerizzazione tissutale delle cellule paratiroidee.] G Chir. 2010 Jun-Jul;31(6-7):312-5 Authors: Iovino F, Armano G, Auriemma PP, Sergio R, De Sena G, Capuozzo V, Rosso F, Marino G, Papale F, Grimaldi A, Barbarisi A Versione italiana Riassunto: L'ingegnerizzazione tissutale delle cellule paratiroidee. F. Iovino, G. Armano, P.P. Auriemma, R. Sergio, G. De Sena, V. Capuozzo, F. Rosso, G. Marino, F. Papale, A. Grimaldi, A. Barbarisi Background. L'ipoparatiroidismo postchirurgico rappresenta un'evenienza tutt'altro che rara dopo intervento di tiroidectomia totale e/o paratiroidectomia totale. I tentativi di trapiantare tessuto paratiroideo sono iniziati nel 1975 con Wells ed i risultati ancora oggi sono alquanto deludenti. Negli ultimi anni grazie a tecniche di ingegneria tissutale si cerca di costruire paratiroidi artificiali,capaci di secernere paratormone, disponibili per il trapianto in pazienti affetti da ipoparatiroidismo iatrogeno. Pazienti e metodi. I paratireociti sono stati ottenuti da paratiroidi di tre pazienti, uremici cronici in emodialisi, operati per iperparatiroidismo secondario. Le colture cellulari ottenute in RPMI sono state successivamente seminate sugli scaffold di collagene (supporti tridimensionali a lenta biodegradazione). Il collagene rappresenta la componente maggioritaria della matrice extracellulare e quindi costituisce un buon substrato su cui le cellule aderiscono e crescono. I terreni di coltura adeguatamente supplementati contenevano bassa concentrazione di calcio e quindi stimolavano in maniera fisiologica i paratireociti a produrre paratormone in maniera costante. Le colture cellulari sono state osservate in microscopia ottica ed in ESEM e sono state sottoposte al test di vitalità MTT fino alla decima settimana. Inoltre è stata misurata la concentrazione di paratormone nel liquido colturale a varie settimane. Risultati. Dopo 24 ore di coltura in RPMI le cellule estratte dalle paratiroidi umane erano quasi tutte adese e raggruppate in clusters tra di loro, a ricordare l'organizzazione ghiandolare. La popolazione cellulare era costituita prevalentemente da paratireociti (90-95%). Seminate sugli scaffold collagenici, a 10 settimane le cellule mantengono una morfologia epithelial-like, arrivando a colonizzare la superficie dello scaffold, conservano una buona progressione proliferativa, associata alla produzione di paratormone. Conclusioni. La scelta di utilizzare paratireociti di pazienti affetti da iperparatiroidismo secondario ha certamente contribuito ad ottenere questi risultati, che, seppur parziali ed in vitro, vanno sperimentati in vivo su modello animale. Il costrutto bioingegnerizzato in scaffold impiantabile nel sottocutaneo può evitare la temuta dispersione delle cellule paratiroidee impiantate e dunque favore la loro agevole rimozione in caso di complicanze. La nostra ricerca ha avuto come obiettivi innanzitutto la realizzazione di colture cellulari di paratireociti umani e successivamente la ingegnerizzazione in vitro di paratiroidi umane all'interno di scaffold tridimensionali collagenici. English version Summary: Tissue engineering of parathyroid gland. F. Iovino, G. Armano, P.P. Auriemma, R. Sergio, G. De Sena, V. Capuozzo, F. Rosso, G. Marino, F. Papale, A. Grimaldi, A. Barbarisi Background. The postoperative hypoparathyroidism is a not rare complication after total thyroidectomy and/or total parathyroidectomy. Attempts to transplant parathyroid tissue began in 1975 with the work of Wells, but still today results are disappointing. However, with the development of tissue engineering techniques, some experimental approaches to build artificial parathyroid are been made. Bioengineered device, actively secreting PTH, for transplant in patients with iatrogenic hypoparathyroidism is unavailable. Patients and methods. Parathyroid cells were obtained from three chronic uremic patients in hemodialysis, operated for secondary hyperparathyroidism. Cell cultures in RPMI medium were subsequently seeded on collagen scaffold (three-dimensional matrix with slow biodegradation). Collagen is the major component of the extracellular matrix and thus is a good substrate for cell adhesion and growth. Culture media, with a low calcium concentration, were optimised to physiologically stimulate parathyroid hormone secretion. Cell cultures were morphologically observed in optical and electron (ESEM) microscopy and metabolically assayed by MTT method until the tenth week. Besides, concentration of parathyroid hormone in the culture medium has been measured for several weeks. Results. After 24 hours of culture in RPMI, cells extracted from human parathyroid glands were nearly all adherent and organised in clusters to resemble the glandular organization. The cellular population consisted predominantly of parathyroid cells (90-95%). On collagen scaffolds, cells maintains an epithelial-like morphology also after 10 weeks, colonizing the scaffold surface and keeping a good proliferative rate with a discrete production of parathyroid hormone. Conclusion. The use of parathyroid cells extracted from patients with secondary hyperparathyroidism was certainly an appropriate choice that enabled us to achieve these results, that albeit partial bode well for the experimental in vivo animal model. The bioengineered scaffolds when implanted in the subcutaneous can avoid the dispersion of parathyroid cells, assuring also the possibility to easily remove the implant in case of complications. Our research was aimed primarily to the optimisation of PTH secreting human parathyroid cells cultures and then to the in vitro engineering of human parathyroid glands in three-dimensional collagen scaffolds. PMID: 20646380 [PubMed - in process] | | |
| Polyurethane scaffolds seeded with genetically engineered skeletal myoblasts: a promising tool to regenerate myocardial function.
July 22, 2010 at 6:46 AM
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| | Polyurethane scaffolds seeded with genetically engineered skeletal myoblasts: a promising tool to regenerate myocardial function. Artif Organs. 2010 Feb;34(2):E46-54 Authors: Blumenthal B, Golsong P, Poppe A, Heilmann C, Schlensak C, Beyersdorf F, Siepe M In animal models, intramyocardial injection of primary skeletal myoblasts is supposed to promote tissue regeneration and to improve cardiac function after myocardial infarction. The usage of genetically engineered myoblasts overexpressing the paracrine factors involved in tissue repair is believed to enhance these effects. However, cell therapy via injection is always accompanied by a high death rate of the injected cells. Here, we describe the construction of a growth factor-producing myoblast-seeded scaffold to overcome this limitation. Skeletal myoblasts were isolated and expanded from newborn Lewis rats. Cells were seeded on polyurethane (PU) scaffolds (Artelon) and transfected with DNA of VEGF-A, HGF, SDF-1, or Akt1 using the lipid-based Metafectene Pro method. Overexpression was verified by ELISA, RT-PCR (VEGF-A, HGF, and SDF-1) and Western blot analysis (Akt1). The seeded scaffolds were transplanted onto damaged myocardium of Lewis rats 2 weeks after myocardial infarction. Six weeks later, their therapeutic potential in vivo was analyzed by measurement of infarction size and capillary density. Primary rat skeletal myoblasts seeded on PU scaffolds were efficiently transfected, achieving transfection rates of 20%. In vitro, we noted a significant increase in expression of VEGF-A, HGF, SDF-1, and Akt1 after transfection. In vivo, transplantation of growth factor-producing myoblast-seeded scaffolds resulted in enhanced angiogenesis (VEGF-A, HGF, and Akt1) or a reduced infarction zone (SDF-1 and Akt1) in the ischemically damaged myocardium. In summary, we constructed a growth factor-producing myoblast-seeded scaffold which combines the beneficial potential of stem cell transplantation with the promising effects of gene-therapeutic approaches. Because this matrix also allows us to circumvent previous cell application drawbacks, it may represent a promising tool for tissue regeneration and the re-establishment of cardiac function after myocardial infarction. PMID: 20420589 [PubMed - indexed for MEDLINE] | | |
| Novel imaging analysis system to measure the spatial dimension of engineered tissue construct.
July 22, 2010 at 6:46 AM
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| | Novel imaging analysis system to measure the spatial dimension of engineered tissue construct. Artif Organs. 2010 Feb;34(2):158-61 Authors: Choi KH, Yoo BS, Park SR, Choi BH, Min BH The measurement of the spatial dimensions of tissue-engineered constructs is very important for their clinical applications. In this study, a novel method to measure the volume of tissue-engineered constructs was developed using iterative mathematical computations. The method measures and analyzes three-dimensional (3D) parameters of a construct to estimate its actual volume using a sequence of software-based mathematical algorithms. The mathematical algorithm is composed of two stages: the shape extraction and the determination of volume. The shape extraction utilized 3D images of a construct: length, width, and thickness, captured by a high-quality camera with charge coupled device. The surface of the 3D images was then divided into fine sections. The area of each section was measured and combined to obtain the total surface area. The 3D volume of the target construct was then mathematically obtained using its total surface area and thickness. The accuracy of the measurement method was verified by comparing the results with those obtained from the hydrostatic weighing method (Korea Research Institute of Standards and Science [KRISS], Korea). The mean difference in volume between two methods was 0.0313 +/- 0.0003% (n = 5, P = 0.523) with no significant statistical difference. In conclusion, our image-based spatial measurement system is a reliable and easy method to obtain an accurate 3D volume of a tissue-engineered construct. PMID: 19995358 [PubMed - indexed for MEDLINE] | | |
| Establishment of three-dimensional tissue-engineered bone constructs under microgravity-simulated conditions.
July 22, 2010 at 6:46 AM
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| | Establishment of three-dimensional tissue-engineered bone constructs under microgravity-simulated conditions. Artif Organs. 2010 Feb;34(2):118-25 Authors: Jin F, Zhang Y, Xuan K, He D, Deng T, Tang L, Lu W, Duan Y Bone constructs have been grown in vitro with use of isolated cells, biodegradable polymer scaffolds, and bioreactors. In our work, the relationships between the composition and mechanical properties of engineered bone constructs were studied by culturing bone marrow mesenchymal stem cells (BMSCs) on ceramic bovine bone scaffolds in different environments: static flasks and dynamic culture system in rotating vessels-which was a National Aeronautics and Space Administration-recommended, ground-based, microgravity-simulating system. After 15 days of cultivation, osteogenicity was determined according to DNA and alkaline phosphatase (ALP) analysis. DNA content and ALP were higher for cells grown on dynamic culture. Subsequently, the two kinds of engineered bone constructs were selected for transplantation into Sprague-Dawley rat cranial bone defects. After 24 weeks of in vivo implantation, the engineered bone constructs under dynamic culture were found to repair the defects better, with the engineered constructs showing histologically better bone connection. Thus, this dynamic system provides a useful in vitro model to construct the functional role and effects of osteogenesis in the proliferation, differentiation, and maturation of BMSCs. These findings suggest that the hydrodynamic microgravity conditions in tissue-culture bioreactors can modulate the composition, morphology, and function of the engineered bone. PMID: 19817729 [PubMed - indexed for MEDLINE] | | |
| Optimization of Targeted Cell Replacement Therapy: A New Approach for Lung Disease.
July 22, 2010 at 6:23 AM
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| | Optimization of Targeted Cell Replacement Therapy: A New Approach for Lung Disease. Mol Ther. 2010 Jul 20; Authors: Duchesneau P, Wong AP, Waddell TK Cell replacement therapy is a promising approach for treatment of lung disease such as cystic fibrosis, although rates of engraftment need to be improved. We previously showed improved cell retention in the lung using transtracheal delivery compared to intravenous injection. Here, we optimized other parameters of cell delivery using 7-day cultured bone marrow cells (BMCs). Retention of BMC in the lung was dose-dependent. Naphthalene treatment had maximal effects on BMC retention when given 2 days before cell delivery. Naphthalene treatment of the donor amplified a CCSP(+) population and increased retention efficiency in the recipient. Repeated naphthalene treatment and repeated cell delivery both resulted in greater retention. The contribution of the second cell dose was minimal suggesting that a second delivery of BMC promotes proliferation of the first. Busulfan-induced myelosuppression augmented retention of exogenous BMC by up to 20-fold. These BMC helped CCSP reconstitution. Using the optimal delivery techniques and cytokeratin-18-driven green fluorescent protein (GFP) reporter mice, we detected threefold more GFP suggesting more BMC differentiated to epithelial cells. We propose that improved engraftment in the lung will increase cell replacement and thus be a more efficient therapeutic approach for various lung diseases. PMID: 20647998 [PubMed - as supplied by publisher] | | |
| Liver-Assist Device With a Microfluidics-Based Vascular Bed in an Animal Model.
July 22, 2010 at 6:23 AM
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| | Liver-Assist Device With a Microfluidics-Based Vascular Bed in an Animal Model. Ann Surg. 2010 Jul 19; Authors: Hsu WM, Carraro A, Kulig KM, Miller ML, Kaazempur-Mofrad M, Weinberg E, Entabi F, Albadawi H, Watkins MT, Borenstein JT, Vacanti JP, Neville C OBJECTIVE:: This study evaluates a novel liver-assist device platform with a microfluidics-modeled vascular network in a femoral arteriovenous shunt in rats. SUMMARY OF BACKGROUND DATA:: Liver-assist devices in clinical trials that use pumps to force separated plasma through packed beds of parenchymal cells exhibited significant necrosis with a negative impact on function. METHODS:: Microelectromechanical systems technology was used to design and fabricate a liver-assist device with a vascular network that supports a hepatic parenchymal compartment through a nanoporous membrane. Sixteen devices with rat primary hepatocytes and 12 with human HepG2/C3A cells were tested in athymic rats in a femoral arteriovenous shunt model. Several parenchymal tube configurations were evaluated for pressure profile and cell survival. The blood flow pattern and perfusion status of the devices was examined by laser Doppler scanning. Cell viability and serum protein secretion functions were assessed. RESULTS:: Femoral arteriovenous shunt was successfully established in all animals. Blood flow was homogeneous through the vascular bed and replicated native flow patterns. Survival of seeded liver cells was highly dependent on parenchymal chamber pressures. The tube configuration that generated the lowest pressure supported excellent cell survival and function. CONCLUSIONS:: This device is the first to incorporate a microfluidics network in the systemic circulatory system. The microvascular network supported viability and function of liver cells in a short-term ex vivo model. Parenchymal chamber pressure generated in an arteriovenous shunt model is a critical parameter that affects viability and must be considered in future designs. The microfluidics-based vascular network is a promising platform for generating a large-scale medical device capable of augmenting liver function in a clinical setting. PMID: 20647924 [PubMed - as supplied by publisher] | | |
| Substrate Elasticity Regulates Skeletal Muscle Stem Cell Self-Renewal in Culture.
July 22, 2010 at 6:23 AM
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| | Substrate Elasticity Regulates Skeletal Muscle Stem Cell Self-Renewal in Culture. Science. 2010 Jul 15; Authors: Gilbert PM, Havenstrite KL, Magnusson KE, Sacco A, Leonardi NA, Kraft P, Nguyen NK, Thrun S, Lutolf MP, Blau HM Freshly isolated muscle stem cells (MuSCs) exhibit robust regenerative capacity in vivo that is rapidly lost in culture. Using a bioengineered substrate to recapitulate key biophysical and biochemical niche features in conjunction with a novel highly automated single cell tracking algorithm, we show that substrate elasticity is a potent regulator of MuSC fate in culture. Unlike MuSCs on rigid plastic dishes (~10(6) kPa), MuSCs cultured on soft hydrogel substrates that mimic the elasticity of muscle (12 kPa) self-renew in vitro and contribute extensively to muscle regeneration when subsequently transplanted into mice and assayed histologically and quantitatively by noninvasive bioluminescence imaging. Our studies provide novel evidence that by recapitulating physiological tissue rigidity, propagation of adult muscle stem cells is possible, enabling future cell-based therapies for muscle wasting diseases. PMID: 20647425 [PubMed - as supplied by publisher] | | |
| Synthesized basement membranes direct the differentiation of mouse embryonic stem cells into pancreatic lineages.
July 22, 2010 at 6:23 AM
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| | Synthesized basement membranes direct the differentiation of mouse embryonic stem cells into pancreatic lineages. J Cell Sci. 2010 Jul 20; Authors: Higuchi Y, Shiraki N, Yamane K, Qin Z, Mochitate K, Araki K, Senokuchi T, Yamagata K, Hara M, Kume K, Kume S We previously reported that embryonic stem (ES) cells cultured on M15 cells, a mesoderm-derived supportive cell line, were efficiently differentiated towards an endodermal fate, finally adopting the specific lineages of various digestive organs such as the pancreas and liver. We show here that the endoderm-inducing activity of M15 cells is in part mediated through the extracellular matrices, and that laminin alpha5 is one of the crucial components. In an attempt to establish a feeder-free ES-cell procedure for pancreatic differentiation, we used a synthesized basement membrane (sBM) substratum using an HEK293 cell line stably expressing laminin-511. On the sBM, mouse ES or induced pluripotent stem (iPS) cells sequentially differentiated into the definitive endoderm, pancreatic progenitor cells, and then insulin-expressing pancreatic beta-cells in vitro. Knockdown of ES cells with integrin beta1 (Itgb1) reduces differentiation towards pancreatic cells. Heparan sulfate proteoglycan 2 (HSPG2) knockdown and heparitinase treatment synergistically decreased the number of Pdx1-expressing cells. These findings indicate that components of the basement membrane have an important role in the differentiation of definitive endoderm lineages. This novel procedure will be useful for the study of pancreatic differentiation of ES or iPS cells and the generation of potential sources of surrogate cells for regenerative medicine. PMID: 20647375 [PubMed - as supplied by publisher] | | |
| Effects of Cryopreservation of Intact Teeth on the Isolated Dental Pulp Stem Cells.
July 22, 2010 at 6:23 AM
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| | Effects of Cryopreservation of Intact Teeth on the Isolated Dental Pulp Stem Cells. J Endod. 2010 Aug;36(8):1336-1340 Authors: Lee SY, Chiang PC, Tsai YH, Tsai SY, Jeng JH, Kawata T, Huang HM INTRODUCTION: Human dental pulp stem cells (DPSCs) have been reported to be useful material for future regenerative medicine. Clinically, cryopreservation of intact teeth can successfully preserve the periodontal ligament for future autotransplantation; however, the effects of cryopreservation procedure on the properties of DPSCs are still unclear. The aim of this study was to test whether DPSCs isolated from cryopreserved teeth can express stem cell-specific markers. METHODS: In this study, a novel programmable freezer coupled to a magnetic field was used to perform the cryopreservation experiments. The tested DPSCs were isolated from magnetically cryopreserved and non-cryopreserved fresh teeth with an enzyme digestion procedure. The success rate of isolation, growth curves, morphology, stem cell-specific markers, and the differentiation capacity of the isolated cells were evaluated and compared. RESULTS: The isolation rate of dental pulp cells from magnetically cryopreserved teeth was 73%. After culture for 5 generations, there was no significant difference in cell viability between cells isolated from magnetically cryopreserved teeth and those isolated from fresh teeth. There were also no visible differences between the 2 groups of dental pulp cells in morphology, expression of stem cell markers, or osteogenic and adipogenic differentiations. CONCLUSIONS: The results suggest that cryopreserved whole teeth can be used for autotransplantation and provide a viable source of DPSCs. PMID: 20647092 [PubMed - as supplied by publisher] | | |
| Cell-adhesive and mechanically tunable glucose-based biodegradable hydrogels.
July 22, 2010 at 6:23 AM
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| | Cell-adhesive and mechanically tunable glucose-based biodegradable hydrogels. Acta Biomater. 2010 Jul 17; Authors: Shin H, Nichol JW, Khademhosseini A The development of materials with biomimetic mechanical and biological properties is of great interest for regenerative medicine applications. In particular, hydrogels are a promising class of biomaterials due to their high water content, which mimic that of natural tissues. We have synthesized a hydrophilic biodegradable polymer, designated poly(glucose malate)methacrylate (PGMma), that is composed of glucose and malic acid which are commonly found in the human metabolic system. This polymer is made photocrosslinkable by the incorporation of methacrylate groups. The resulting properties of the hydrogels can be tuned by altering the reacting ratio of the starting materials, the degree of methacrylation, and the polymer concentration of the resultant hydrogel. Hydrogels exhibited compressive moduli ranging from 1.8 +/- 0.4kPa to 172.7 +/- 36kPa with compressive strain at failure from 37.5 +/- 0.9% to 61.2 +/- 1.1%, and hydration by mass ranging from 18.7 +/- 0.5% to 114.1 +/- 1.3%. PGMma hydrogels also showed a broad range of degradation rates and were cell-adhesive, enabling the spreading of adherent cells. Overall, this work introduces a class of cell adhesive, mechanically tunable and biodegradable glucose-based hydrogels that may be useful for various tissue engineering and cell culture applications. PMID: 20647064 [PubMed - as supplied by publisher] | | |
| Protein-engineered biomaterials: Nanoscale mimics of the extracellular matrix.
July 22, 2010 at 6:23 AM
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| | Protein-engineered biomaterials: Nanoscale mimics of the extracellular matrix. Biochim Biophys Acta. 2010 Jul 17; Authors: Romano N, Sengupta D, Chung C, Heilshorn SC BACKGROUND: Traditional materials used as in vitro cell culture substrates are rigid and flat surfaces that lack the exquisite nano- and micro-scale features of the in vivo extracellular environment. While these surfaces can be coated with harvested extracellular matrix (ECM) proteins to partially recapitulate the bio-instructive nature of the ECM, these harvested proteins often exhibit large batch-to-batch variability and can be difficult to customize for specific biological studies. In contrast, recombinant protein technology can be utilized to synthesize families of protein-engineered biomaterials that are cyto-compatible, reproducible, and fully customizable. SCOPE OF REVIEW: Here we describe a modular design strategy to synthesize protein-engineered biomaterials that fuse together multiple repeats of nanoscale peptide design motifs into full-length engineered ECM mimetics. MAJOR CONCLUSIONS: Due to the molecular-level precision of recombinant protein synthesis, these biomaterials can be tailored to include a variety of bio-instructional ligands at specified densities, to exhibit mechanical properties that match those of native tissue, and to include proteolytic target sites that enable cell-triggered scaffold remodeling. Furthermore, these biomaterials can be processed into forms that are injectable for minimally-invasive delivery or spatially patterned to enable the release of multiple drugs with distinct release kinetics. GENERAL SIGNIFICANCE: Given the reproducibility and flexibility of these protein-engineered biomaterials, they are ideal substrates for reductionist biological studies of cell-matrix interactions, for in vitro models of physiological processes, and for bio-instructive scaffolds in regenerative medicine therapies. PMID: 20647034 [PubMed - as supplied by publisher] | | |
| Grafting of GABAergic precursors rescues deficits in hippocampal inhibition.
July 22, 2010 at 6:23 AM
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| | Grafting of GABAergic precursors rescues deficits in hippocampal inhibition. Epilepsia. 2010 Jul;51 Suppl 3:66-70 Authors: Calcagnotto ME, Zipancic I, Piquer-Gil M, Mello LE, Alvarez-Dolado M gamma-Aminobutyric acid (GABA) has an important role in the mechanism of epilepsy. Cell grafts from different sources have been performed to modulate local circuits or increase GABAergic inhibition in animal models of epilepsy. Among the different transplanted cell types, the medial ganglionic eminence (MGE)-derived cells present the best properties to be used in cell-based therapy. In this work we review previous experiences with these cells. In addition, we present new evidence showing their ability to modulate the levels of inhibition in the host brain of mice with alterations in the GABAergic system, caused by the specific ablation of hippocampal interneurons. Grafted GFP(+) MGE-derived cells occupied the area of ablation and differentiated into mature NK-1-, SOM-, PV-, CR-, and NPY-expressing interneurons. Inhibitory postsynaptic current (IPSC) frequency and amplitude on CA1 pyramidal cells of the ablated hippocampus significantly increased after transplantation, reaching levels similar to controls. Our data strongly suggest the suitability of MGE-derived cells for the treatment of neurologic conditions for which an increase or modulation of synaptic inhibition is required. PMID: 20618404 [PubMed - in process] | | | | 
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