| U of M researchers find 2 units of umbilical cord blood reduce risk of leukemia recurrence
November 13, 2009 at 4:27 pm
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| Advanced BioHealing's Dean Tozer to Participate in Panel on Convergence Technologies at Stem Cells USA
November 13, 2009 at 10:26 am
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| Paradoxical protein might prevent cancer
November 13, 2009 at 10:26 am
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| Genetics Policy Institute (GPI) and NABT to Launch Stem Cell Educational Summit in Denver
November 13, 2009 at 9:17 am
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| Isolation and Culture of Hair Follicle Pluripotent Stem (hfPS) Cells and Their Use for Nerve and Spinal Cord Regeneration.
November 13, 2009 at 7:05 am
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| | Isolation and Culture of Hair Follicle Pluripotent Stem (hfPS) Cells and Their Use for Nerve and Spinal Cord Regeneration. Methods Mol Biol. 2010;585:401-20 Authors: Amoh Y, Hoffman RM The hair follicle is dynamic, cycling between growth (anagen), regression (catagen), and resting (telogen) phases throughout life. We have demonstrated that nestin-expressing hair follicle stem cells give rise to follicle structures during early anagen or growth phase of the hair follicle. Nestin-expressing hair follicle stem cells appear in the hair follicular stem cell area, the permanent upper hair follicle immediately below the sebaceous glands and above the bulge area. The nestin-expressing hair follicle stem cells can differentiate into neurons, glia, keratinocytes, smooth muscle cells, and melanocytes in vitro. Furthermore, the hair follicle stem cells promote the recovery of peripheral nerve and spinal cord injury. We have termed these cells hair follicle pluripotent stem (hfPS) cells. These results suggest that hfPS cells provide an important accessible, autologous source of adult stem cells with potential for use in regenerative medicine. PMID: 19908019 [PubMed - in process] |
| Identification of Epithelial Stem Cells In Vivo and In Vitro Using Keratin 19 and BrdU.
November 13, 2009 at 7:05 am
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| | Identification of Epithelial Stem Cells In Vivo and In Vitro Using Keratin 19 and BrdU. Methods Mol Biol. 2010;585:383-400 Authors: Larouche D, Lavoie A, Paquet C, Simard-Bisson C, Germain L Progress in the identification of skin stem cells and the improvement of culture methods open the possibility to use stem cells in regenerative medicine. Based on their quiescent nature, the development of label retention assays allowed the localization of skin stem cells in the bulge region of the pilosebaceous units and in the bottom of rete ridges in glabrous skin. The development of markers such as keratin 19 also permits their study in human tissues. In this chapter, protocols to identify skin stem cells based on their slow-cycling property and their expression of keratin 19 will be described in detail. The methods include the labeling of skin stem cells within mouse or rat tissues in vivo, the labeling of proliferative human cells in vitro using 5-bromo-2-deoxyuridine (BrdU), and the detection of keratin 19 and BrdU by immunofluorescence or immunoperoxidase staining. PMID: 19908018 [PubMed - in process] |
| A Versatile Murine 3D Organotypic Model to Evaluate Aspects of Wound Healing and Epidermal Organization.
November 13, 2009 at 7:05 am
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| | A Versatile Murine 3D Organotypic Model to Evaluate Aspects of Wound Healing and Epidermal Organization. Methods Mol Biol. 2010;585:303-12 Authors: Kandyba E, Hodgins M, Martin P Three-dimensional (3D) organotypic models are increasingly being used to study aspects of epidermal organisation and cutaneous wound-healing events. These are largely dependent on laborious histological analysis and immunohistochemical approaches. Here we outline a method for establishment of a versatile in vitro 3D organotypic skin equivalent that reflects murine epidermal organisation in vivo. The system is optically transparent and ideally suited to real-time analysis and integrated in situ imaging techniques. Moreover, the model permits the visualisation of epidermal regeneration following injury in real time, thereby facilitating avenues to explore distinctive modes of wound re-epithelialisation. The versatility of the model could help unravel molecular mechanisms underlying epidermal morphogenesis, assess novel therapeutic strategies and reduce animal experimentation in a non-invasive manner. PMID: 19908012 [PubMed - in process] |
| Human-induced pluripotent stem cells: derivation, propagation, and freezing in serum- and feeder layer-free culture conditions.
November 13, 2009 at 7:05 am
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| | Human-induced pluripotent stem cells: derivation, propagation, and freezing in serum- and feeder layer-free culture conditions. Methods Mol Biol. 2010;584:425-43 Authors: Baharvand H, Totonchi M, Taei A, Seifinejad A, Aghdami N, Salekdeh GH The recent discovery of genomic reprogramming of human somatic cells to an embryonic stem (ES) cell-like pluripotent state provides a unique opportunity for stem cell research. The reprogrammed cells, named as induced pluripotent stem (iPS) cells, possess many of the properties of ES cells and represent one of the most promising sources of patient-specific cells for use in disease model, development of pharmacology and toxicology, screening teratogens, and regenerative medicine. Here we describe the detailed methods for the generation of undifferentiated human iPS (hiPS) cells in feeder layer- and serum-free conditions. This system eliminates direct contact of stem cells with MEFs and reduces use of unknown serum factors that may have undesired activities and enables consistency in large-scale and long-term expansion of undifferentiated hiPS cells. Our findings greatly simplify the method for induction of pluripotency and bring it one step closer to clinical applications. Moreover, the established hiPS cells showed chromosomal stability during long-term culture. PMID: 19907991 [PubMed - in process] |
| Vascular differentiation of human embryonic stem cells in bioactive hydrogel-based scaffolds.
November 13, 2009 at 7:05 am
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| | Vascular differentiation of human embryonic stem cells in bioactive hydrogel-based scaffolds. Methods Mol Biol. 2010;584:333-54 Authors: Gerecht S, Ferreira LS, Langer R The vascularization of tissue constructs remains a major challenge in regenerative medicine, as the diffusional supply of oxygen can support only 100-200 mum thick layers of viable tissue. The formation of a mature and functional vascular network requires communication between endothelial cells (ECs) and smooth muscle cells (SMCs). Potential sources of these cells that involve noninvasive methodologies are required for numerous applications including tissue-engineered vascular grafts, myocardial ischemia, wound healing, plastic surgery, and general tissue-engineering applications. Human embryonic stem cells (hESCs) can be an unlimited source of these cells. They can be expanded in vitro in an undifferentiated state without apparent limit, and hES-derived cells can be created in virtually unlimited amounts for potential clinical uses. Recently, vascular progenitor cells as well as endothelial and smooth muscle cells have been isolated from hESCs. PMID: 19907986 [PubMed - in process] |
| In vitro derivation of chondrogenic cells from human embryonic stem cells.
November 13, 2009 at 7:05 am
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| | In vitro derivation of chondrogenic cells from human embryonic stem cells. Methods Mol Biol. 2010;584:317-31 Authors: Toh WS, Lee EH, Richards M, Cao T Human embryonic stem cells (hESCs) have the ability to self-renew and differentiate into any cell lineage of the three germ layers, therefore holding great promise for regenerative medicine applications. However, directing lineage-restricted differentiation of hESCs and obtaining a homogenous differentiated cell population is still a challenge. We previously described a micromass culture system as a model system to study chondrogenic commitment of the hESCs. Using this system, various growth factors including BMP2 and TGFbeta1 direct chondrogenic differentiation and modulate cartilage-specific matrix gene expression in a distinctive manner. Furthermore, a high percentage of differentiated cells exhibit typical morphological characteristics of chondrocytes and express cartilage matrix proteins such as type II collagen and proteoglycans. Chondrogenic cells can be further isolated and cultured to form functional cartilage tissue in vitro. Here, we describe in detail our established protocols to analyze chondrogenic differentiation of hESCs, and possible isolation of chondrogenic cells to form functional cartilaginous tissue. PMID: 19907985 [PubMed - in process] |
| Neural relay from the liver induces proliferation of pancreatic beta cells: A path to regenerative medicine using the self-renewal capabilities.
November 13, 2009 at 7:05 am
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| | Neural relay from the liver induces proliferation of pancreatic beta cells: A path to regenerative medicine using the self-renewal capabilities. Commun Integr Biol. 2009 Sep;2(5):425-7 Authors: Katagiri H, Imai J, Oka Y Systemic homeostasis requires coordinated metabolic regulation among multiple tissues/organs via inter-organ communication. We have reported that neuronal signaling plays important roles in this inter-organ metabolic communication. First, we found that liver-selective extracellular signal-regulated kinase (ERK) activation induces insulin hypersecretion and pancreatic beta cell proliferation. Denervation experiments revealed that these inter- organ (liver-to-pancreas) effects are mediated by a neural relay consisting of splanchnic afferents (from the liver) and vagal efferents (to the pancreas). The central nervous system also participates in this inter-organ communication. This neural relay system originating in the liver is physiologically involved in the anti-diabetes mechanism whereby, during obesity development, insulin hypersecretion and pancreatic beta cell hyperplasia occur in response to insulin resistance. This indicates the pathophysiological importance of this system in diabetes prevention and hyperinsulinemia development. Furthermore, when applied to mouse models of insulin-deficient diabetes, both type 1 and type 2, hepatic activation of ERK signaling increased pancreatic beta cell mass and normalized blood glucose. Thus, this inter-organ system may serve as a valuable therapeutic target for diabetes by regenerating pancreatic beta cells. The concept that manipulation of an endogenous mechanism can regenerate a damaged tissue in vivo may open a new paradigm for regenerative trreatments for degenerative disorders. PMID: 19907708 [PubMed - in process] |
| Workshop on 'Translational Models for Musculoskeletal Tissue Engineering and Regenerative Medicine'
November 13, 2009 at 7:05 am
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| | Workshop on 'Translational Models for Musculoskeletal Tissue Engineering and Regenerative Medicine' Tissue Eng Part B Rev. 2009 Nov 11; Authors: Sah RL, Ratcliffe A The NIH-sponsored workshop 'Translational Models for Musculoskeletal Tissue Engineering and Regenerative Medicine' was held to describe the utility of various translational models for engineered tissues and regenerative medicine therapies targeting intervertebral disc, cartilage, meniscus, ligament, tendon, muscle, and bone. Participants included leaders in the various topics, as well as NIH and FDA. The FDA representatives provided perspectives and needs for studies supported by animal models. Researchers described animal models for specific tissues and addressed the following questions: (1) what are the unmet musculoskeletal clinical needs that may be addressed by tissue engineering and regenerative medicine; (2) are there appropriate models available; (3) are there needs to develop standardized animal models; and (4) what are the translational pathways that lead to clinical trials and therapeutic development. Overall, the workshop provided an effective and succinct summary of the status of various animal models in musculoskeletal regenerative medicine. While many models are available and serve well to answer a variety of questions, the general consensus was that there is a substantial need for improved and standardized animals models throughout the field for tissue engineering and regenerative medicine of the musculoskeletal system, and that animal models, especially large animal models, are critical preclinical step for translating research from bench to bedside. PMID: 19905871 [PubMed - as supplied by publisher] |
| A novel bioactive three-dimensional beta-tricalcium phosphate/chitosan scaffold for periodontal tissue engineering.
November 13, 2009 at 6:35 am
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| | A novel bioactive three-dimensional beta-tricalcium phosphate/chitosan scaffold for periodontal tissue engineering. J Mater Sci Mater Med. 2009 Nov 12; Authors: Liao F, Chen Y, Li Z, Wang Y, Shi B, Gong Z, Cheng X The development of suitable bioactive three-dimensional scaffold for the promotion of cellular proliferation and differentiation is critical in periodontal tissue engineering. In this study,porous beta-tricalcium phosphate/chitosan composite scaffolds were prepared through a freeze-drying method. These scaffolds were evaluated by analysis of microscopic structure, porosity, and cytocompatibility. The gene expression of bone sialoprotein (BSP) and cementum attachment protein (CAP) was detected with RT-PCR after human periodontal ligament cells (HPLCs) were seeded in these scaffolds. Then cell-scaffold complexes were implanted subcutaneously into athymic mice. The protein expression of alkaline phosphatase (ALP) and osteopontin (OPN) was detected in vivo. Results indicated that composite scaffolds displayed a homogeneous three-dimensional microstructure; suitable pore size (120 mum) and high porosity (91.07%). The composite scaffold showed higher proliferation rate than the pure chitosan scaffold, and up-regulated the gene expression of BSP and CAP. In vivo, HPLCs in the composite scaffold not only proliferated but also recruited vascular tissue ingrowth. The protein expression of ALP and OPN was up-regulated in the composite scaffold. Therefore, it was suggested that the composite scaffold could promote the differentiation of HPLCs towards osteoblast and cementoblast phenotypes. PMID: 19908128 [PubMed - as supplied by publisher] |
| Three-dimensional human tissue models of wounded skin.
November 13, 2009 at 6:35 am
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| | Three-dimensional human tissue models of wounded skin. Methods Mol Biol. 2010;585:345-59 Authors: Egles C, Garlick JA, Shamis Y Human skin equivalents (HSEs) are in vitro tissues in which a fully differentiated, stratified squamous epithelium is grown at an air-liquid interface on a Type I collagen gel harboring human dermal fibroblasts. HSEs now provide experimental human tissue models to study factors that direct re-epithelialization and epithelial-mesenchymal cross-talk following wounding. This chapter describes the fabrication of HSEs from human keratinocytes and fibroblasts and how HSEs can be modified to characterize the response of the human epithelium during wound repair. The protocols outlined first describe techniques for the generation of human tissues that closely approximate the architectural features, differentiation, and growth of human skin. This will be followed by a description of a protocol that enables HSEs to be adapted to monitor their response following wounding. These engineered human tissues provide powerful tools to study biological process in tissues that mimic the healing of human skin and of the epithelial tissue. PMID: 19908015 [PubMed - in process] |
| Growth and stratification of epithelial cells in minimal culture conditions.
November 13, 2009 at 6:35 am
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| | Growth and stratification of epithelial cells in minimal culture conditions. Methods Mol Biol. 2010;585:25-43 Authors: Riva F, Casasco A, Casasco M, Calligaro A, Cornaglia AI Biological risk management is required in modern tissue engineering. Particular attention should be paid to the culture medium and the scaffold used. In this perspective, it is important to define minimal culture conditions which allow proper growth and differentiation of epithelial cells in vitro. We propose a simple experimental system which permits the generation of three-dimensional epidermal constructs using a collagen layer as a scaffold mimicking the entire dermal tissue and without the need of any feeder layer. Although showing significant differences compared to natural epidermis, these epidermal constructs appear useful to study keratinocyte differentiation and epidermis histogenesis. PMID: 19907994 [PubMed - in process] |
| Vascular differentiation of human embryonic stem cells in bioactive hydrogel-based scaffolds.
November 13, 2009 at 6:35 am
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| | Vascular differentiation of human embryonic stem cells in bioactive hydrogel-based scaffolds. Methods Mol Biol. 2010;584:333-54 Authors: Gerecht S, Ferreira LS, Langer R The vascularization of tissue constructs remains a major challenge in regenerative medicine, as the diffusional supply of oxygen can support only 100-200 mum thick layers of viable tissue. The formation of a mature and functional vascular network requires communication between endothelial cells (ECs) and smooth muscle cells (SMCs). Potential sources of these cells that involve noninvasive methodologies are required for numerous applications including tissue-engineered vascular grafts, myocardial ischemia, wound healing, plastic surgery, and general tissue-engineering applications. Human embryonic stem cells (hESCs) can be an unlimited source of these cells. They can be expanded in vitro in an undifferentiated state without apparent limit, and hES-derived cells can be created in virtually unlimited amounts for potential clinical uses. Recently, vascular progenitor cells as well as endothelial and smooth muscle cells have been isolated from hESCs. PMID: 19907986 [PubMed - in process] |
| Human embryonic stem cell differentiation on periodontal ligament fibroblasts.
November 13, 2009 at 6:35 am
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| | Human embryonic stem cell differentiation on periodontal ligament fibroblasts. Methods Mol Biol. 2010;584:269-81 Authors: Elçin YM, Inanç B, Elçin AE Human embryonic stem cells' (hESCs) unlimited proliferative potential and differentiation capability to all somatic cell types made them potential cell source in different cell-based tissue engineering strategies as well as various experimental applications in fields such as developmental biology, pharmacokinetics, toxicology, and genetics. Periodontal tissue engineering aims to improve the outcome of regenerative therapies which have variable success rates when contemporary techniques are used. Cell-based therapies may offer potential advantage in overcoming the inherent limitations associated with guided tissue-regeneration procedures, such as dependency on defect type and size and the pool and capacity of progenitor cells resident in the wound area. Elucidation of developmental mechanisms of different periodontal tissues may also contribute to valuable knowledge based upon which the future therapies can be designed. Prior to the realization of such a potential, protocols for the differentiation of pluripotent hESCs into periodontal ligament fibroblastic cells (PDLF) as common progenitors for ligament, cementum, and alveolar bone tissue need to be developed. The present protocol describes methods associated with the guided differentiation of hESCs by the use of coculture with adult PDLFs, and the resulting change of morphotype and phenotype of the pluripotent embryonic stem cells toward fibroblastic and osteoblastic lineages. PMID: 19907982 [PubMed - in process] |
| In vitro neural differentiation of human embryonic stem cells using a low-density mouse embryonic fibroblast feeder protocol.
November 13, 2009 at 6:35 am
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| | In vitro neural differentiation of human embryonic stem cells using a low-density mouse embryonic fibroblast feeder protocol. Methods Mol Biol. 2010;584:71-95 Authors: Ozolek JA, Jane EP, Esplen JE, Petrosko P, Wehn AK, Erb TM, Mucko SE, Cote LC, Sammak PJ Human embryonic stem cells (hESCs) have the capacity to self-renew and to differentiate into all components of the embryonic germ layers (ectoderm, mesoderm, endoderm) and subsequently all cell types that comprise human tissues. HESCs can potentially provide an extraordinary source of cells for tissue engineering and great insight into early embryonic development. Much attention has been given to the possibility that hESCs and their derivatives may someday play major roles in the study of the development, disease therapeutics, and repair of injuries to the central and peripheral nervous systems. This tantalizing promise will be realized only when we understand fundamental biological questions about stem cell growth and development into distinct tissue types. In vitro, differentiation of hESCs into neurons proceeds as a multistep process that in many ways recapitulates development of embryonic neurons. We have found in vitro conditions that promote differentiation of stem cells into neuronal precursor or neuronal progenitor cells. Specifically, we have investigated the ability of two federally approved hESC lines, HSF-6 and H7, to form embryonic and mature neuronal cells in culture. Undifferentiated hESCs stain positively for markers of undifferentiated/pluripotent hESCs including surface glycoproteins, SSEA-3 and 4, and transcription factors Oct-3/4 and Nanog. Using reduced numbers of mouse embryonic fibroblasts as feeder substrates, these markers of pluripotency are lost quickly and replaced by primarily neuroglial phenotypes with only a few cells representing other embryonic germ layer types remaining. Within the first 2 weeks of co-culture with reduced MEFs, the undifferentiated hESCs show progression from neuroectodermal to neural stem cell to maturing and migrating neurons to mature neurons in a stepwise fashion that is dependent on both the type of hESCs and the density of MEFs. In this chapter, we provide the methods for culturing pluripotent hESCs and MEFs, differentiating hESCs using reduced density MEFs, and phenotypic analyses of this culture system. PMID: 19907972 [PubMed - in process] |
| Preparation, characterization, and encapsulation/release studies of a composite nanofiber mat electrospun from an emulsion containing poly (lactic-co-glycolic acid).
November 13, 2009 at 6:35 am
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| | Preparation, characterization, and encapsulation/release studies of a composite nanofiber mat electrospun from an emulsion containing poly (lactic-co-glycolic acid). Polymer (Guildf). 2008 Nov 10;49(24):5294-5299 Authors: Liao Y, Zhang L, Gao Y, Zhu ZT, Fong H The aim of this study was to investigate the preparation, characterization, and encapsulation/release performance of an electrospun composite nanofiber mat. The hypothesis was that the composite nanofiber mat with nano-scaled drug particles impregnated in biocompatible and biodegradable polymer nanofibers can serve as an innovative type of tissue engineering scaffold with desired and controllable drug encapsulation/release properties. To test the hypothesis, the composite nanofiber mat electrospun from an emulsion consisting of poly (lactic-co-glycolic acid) (PLGA) Rhodamine B (a model compound to simulate drugs), sorbitan monooleate (Span-80, a non-ionic emulsifier/surfactant that is presumably non-toxic/safe for cell-growth), chloroform, DMF, and distilled water was prepared and characterized; and the Rhodamine B encapsulation/release profile in phosphate buffered saline (pH = 7.4) was recorded and analyzed. For comparison purposes, two additional nanofiber mats electrospun from (1) a solution containing PLGA and Rhodamine B, and (2) a solution containing PLGA, Rhodamine B, and Span-80 were also prepared and assessed as the control samples. The results indicated that the composite nanofiber mat electrospun from the emulsion had the most desired and controllable Rhodamine B encapsulation/release profile and the excellent morphological sustainability; thus, it could be utilized as both a drug encapsulation/release vehicle and a tissue engineering scaffold. PMID: 19907634 [PubMed - as supplied by publisher] |
| Bmi-1 Reduction Plays a Key Role in Physiological and Premature Aging of Primary Human Keratinocytes.
November 13, 2009 at 6:35 am
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| | Bmi-1 Reduction Plays a Key Role in Physiological and Premature Aging of Primary Human Keratinocytes. J Invest Dermatol. 2009 Nov 12; Authors: Cordisco S, Maurelli R, Bondanza S, Stefanini M, Zambruno G, Guerra L, Dellambra E Accumulation of senescent cells contributes to the reduced regenerative capacity in aged tissues. By evaluating the molecular pathways of senescence in relation to proliferative potential of primary keratinocyte cultures from young and old healthy donors, and from young patients with inherited defects leading to premature aging, we demonstrated that p16(INK4a) is a reliable marker of both physiological and premature epidermal aging. Analysis of the expression and activity of p16(INK4a) regulators showed that stem cell depletion, reduced proliferation, and p16(INK4a) upregulation in keratinocytes derived from the chronologically and prematurely aged epidermis strongly correlate with Bmi-1 downregulation. In highly proliferative tissues, replicative and premature senescence participate in determining senescent cell accumulation. Our findings demonstrated that Bmi-1 is downregulated in human keratinocytes during both in vitro processes, in parallel with p16(INK4a) upregulation and accomplishment of clonal conversion. When premature senescence was induced by specific exogenous stimuli, concomitant Ets-1 upregulation was also observed. Moreover, Bmi-1 inhibited Ets-1-mediated p16(INK4a) upregulation. Finally, Bmi-1 overexpression reduced p16(INK4a) promoter activity and decreased protein expression in aged and diseased keratinocytes, inducing a delay of clonal conversion and an increase of cell clonogenic ability. Altogether these findings underline a key role of Bmi-1 downregulation in enforcing aging in primary human keratinocytes.Journal of Investigative Dermatology advance online publication, 12 November 2009; doi:10.1038/jid.2009.355. PMID: 19907431 [PubMed - as supplied by publisher] |
| Soft tissue augmentation using silk gels: an in vitro and in vivo study.
November 13, 2009 at 6:35 am
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| | Soft tissue augmentation using silk gels: an in vitro and in vivo study. J Periodontol. 2009 Nov;80(11):1852-8 Authors: Etienne O, Schneider A, Kluge JA, Bellemin-Laponnaz C, Polidori C, Leisk GG, Kaplan DL, Garlick JA, Egles C BACKGROUND: Restoration of a three-dimensional shape with soft tissue augmentation is a challenge for surgical reconstruction and esthetic improvement of intraoral mucosa and perioral skin tissues. A connective tissue graft or free gingival graft, classically used for such indications, requires a donor site, which may lead to various clinical complications. METHODS: In this article, a new three-dimensional scaffold made of silk fibroin that could be of great interest for these indications was studied. Mechanical tests were conducted to characterize the physical properties of the materials. The biocompatibility of such scaffolds was positively assessed in vitro using a combination of immunostaining, 5-bromo-2'-deoxyuridine proliferation assays, and histologic staining. Finally, the shaped material was grafted subcutaneously in nude mice for a long-time implantation study. RESULTS: Human fibroblasts embedded in this material had a survival rate up to 68.4% and were able to proliferate and synthesize proteins. One month after subcutaneous implantation, the three-dimensional soft tissue augmentation was stable, and histologic analysis revealed revascularization of the area through the biomaterial. A mild inflammatory reaction disappeared after 12 weeks. CONCLUSION: The results indicate that silk-gel material was able to create a lasting three-dimensional soft tissue augmentation and is a promising biomaterial for periodontal and maxillofacial therapies, either as a scaffold for cells or alone as a biomaterial. PMID: 19905955 [PubMed - in process] |
| Re: "Clinical evaluation of a modified coronally advanced flap alone or in combination with a platelet-rich fibrin membrane for the treatment of adjacent multiple gingival recessions: a 6-month study".
November 13, 2009 at 6:35 am
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| | Re: "Clinical evaluation of a modified coronally advanced flap alone or in combination with a platelet-rich fibrin membrane for the treatment of adjacent multiple gingival recessions: a 6-month study". J Periodontol. 2009 Nov;80(11):1694-7; author reply 1697-9 Authors: Del Corso M, Sammartino G, Ehrenfest DM Choukroun's platelet-rich fibrin (PRF) is a fibrin biomaterial with a specific composition, three-dimensional architecture, and associated biology. This letter highlights some key issues related to the use of this complex material during periodontal surgery. First, a reproducible protocol for the production of PRF membranes must be followed to control the quantity and quality of the fibrin matrix, leukocytes, platelets, and growth factors. Second, its use in periodontology must follow two principles founded on tissue-engineering basic rules and classical periodontal concepts. Using this two-principle safe protocol, the use of PRF in periodontal surgery leads to a significant improvement during the early healing phase and to a thick and stable final remodeled gingiva. PMID: 19905939 [PubMed - in process] |
| Generation of Porous Poly(ethylene glycol) Hydrogels by Salt Leaching.
November 13, 2009 at 6:35 am
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| | Generation of Porous Poly(ethylene glycol) Hydrogels by Salt Leaching. Tissue Eng Part C Methods. 2009 Nov 11; Authors: Chiu YC, Larson JC, Isom Jr A, Brey EM Poly(ethylene glycol) (PEG) hydrogels have been investigated for a number of applications in tissue engineering. The hydrogels can be designed to mimic tissues in chemical and mechanical properties, but their physical structure can hinder cell migration, tissue invasion, and molecular transport. Synthesis of porous PEG hydrogels could improve transport, enhance cell behavior, and increase the surface area available for cell adhesion. Salt leaching methods have been used extensively to generate porous biomaterial scaffolds but have not previously been applied to hydrogels. In this paper we describe a modification of traditional salt leaching techniques for application to hydrogels. Salt saturated polymer precursor solutions are prepared and salt crystals of defined size are added prior to polymerization. The salt crystals are then leached out resulting in porous hydrogels. Examples are are provided for application of this technique to PEG hydrogels. Porous PEG hydrogels were generated with pore sizes ranging from 15 to 86 microm and porosities from 30 to 75%. Porous hydrogels incorporated with a cell adhesion peptide supported cell adhesion with morphology varying with pore size. The simple, reproducible technique described here could be used to generate porous hydrogels with controlled pore size for applications in tissue engineering. PMID: 19905877 [PubMed - as supplied by publisher] |
| Both the Transplantation of Somatic Cell Nuclear Transfer - and Fertilization-Derived-mouse Embryonic Stem Cells with Temperature-responsive Chitosan Hydrogel Improve Myocardial Performance in Infarcted Rat Hearts.
November 13, 2009 at 6:35 am
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| | Both the Transplantation of Somatic Cell Nuclear Transfer - and Fertilization-Derived-mouse Embryonic Stem Cells with Temperature-responsive Chitosan Hydrogel Improve Myocardial Performance in Infarcted Rat Hearts. Tissue Eng Part A. 2009 Nov 11; Authors: Lü SH, Wang H, Lu WN, Liu S, Lin Q, Li D, Duan C, Hao T, Zhou J, Wang YM, Gao SG, Wang CY The transplantation of embryonic stem cells could improve the cardiac function but was limited by immune rejection as well as low cell retention and survival within the ischemic tissues. The somatic cell nuclear transfer (SCNT) is practical to generate autologous histocompatible stem (NTES) cells for diseases, but NTES may be arguably unsafe for therapeutic application. The temperature-responsive chitosan hydrogel is a suitable matrix in cell transplantation. As the scaffold, chitosan hydrogel was co-injected with NT-ES cell into the left ventricular wall of rat infarction models. Detailed histological analysis and echocardiography were used to determine the structure and functional consequences of transplantation. The myocardial performance in SCNT- and fertilization-derived-mESC transplantation with chitosan hydrogel was compared, too. The result showed that both the 24h-cell retention and 4-week graft size were significantly greater in the NT-ES + chitosan group than that of NT-ES + PBS group (p<0.01). The NTES cells might differentiate into cardiomyocytes in vivo. The heart function improved significantly in the chitosan + NTES group (FS: 28.7 +/- 2.8%) compared with that of PBS + NTES group (FS: 25.2 +/- 2.9%) 4 weeks after transplantation (p<0.01). In addition, the arteriole/venule densities within the infarcted area improved significantly in the chitosan + NTES group (280 +/- 17/mm2) compared with that of PBS + NTES group (234 +/-16/mm2) 4 weeks after transplantation (p<0.01). There was no difference in the myocardial performance in SCNT- and fertilization-derived-mESC transplantation with chitosan hydrogel. The NTES cells with chitosan hydrogel are proved with therapeutic potential to improve the function of infarcted heart. Thus the method of in situ injectable tissue engineering is promising clinically. PMID: 19905874 [PubMed - as supplied by publisher] | | | 
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