|  |  |  | | | | | pubmed: "regenerative medici... | | | | | | | | | | | | | | | | | | | Novel Hyperactive Transposons for Genetic Modification of Induced Puripotent and Adult Stem Cells: A Non-Viral Paradigm for Coaxed Differentiation. Stem Cells. 2010 Aug 16; Authors: Belay E, Mátrai J, Acosta-Sanchez A, Ma L, Quattrocelli M, Mátés L, Sancho-Bru P, Geraerts M, Yang B, Joris V, Rincón MY, Samara-Kuko E, Ivics Z, Verfaillie CM, Sampaolesi M, Izsvák Z, Vandendriessche T, Chuah MK Adult stem cells and induced pluripotent stem cells (iPS) hold great promise for regenerative medicine. The development of robust non-viral approaches for stem cell gene transfer would facilitate functional studies and potential clinical applications. We have previously generated hyperactive transposases derived from Sleeping Beauty, using an in vitro molecular evolution and selection paradigm. We now demonstrate that these hyperactive transposases resulted in superior gene transfer efficiencies and expression in mesenchymal and muscle stem/progenitor cells, consistent with higher expression levels of therapeutically relevant proteins including coagulation factor IX. Their differentiation potential and karyotype was not affected. Moreover, stable transposition could also be achieved in iPS which retained their ability to differentiate along neuronal, cardiac and hepatic lineages without causing cytogenetic abnormalities. Most importantly, transposon-mediated delivery of the myogenic PAX3 transcription factor into iPS coaxed their differentiation into MYOD(+) myogenic progenitors and multinucleated myofibers, suggesting that PAX3 may serve as a myogenic "molecular switch" in iPS. Hence, this hyperactive transposon system represents an attractive non-viral gene transfer platform with broad implications for regenerative medicine, cell and gene therapy. PMID: 20715185 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The Use of Fibrous, Supramolecular Membranes and Human Tubular Cells for Renal Epithelial Tissue Engineering: Towards a Suitable Membrane for a Bioartificial Kidney. Macromol Biosci. 2010 Aug 16; Authors: Dankers PY, Boomker JM, der Vlag AH, Smedts FM, Harmsen MC, van Luyn MJ A bioartificial kidney, which is composed of a membrane cartridge with renal epithelial cells, can substitute important kidney functions in patients with renal failure. A particular challenge is the maintenance of monolayer integrity and specialized renal epithelial cell functions ex vivo. We hypothesized that this can be improved by electro-spun, supramolecular polymer membranes which show clear benefits in ease of processability. We found that after 7 d, in comparison to conventional microporous membranes, renal tubular cells cultured on top of our fibrous supramolecular membranes formed polarized monolayers, which is prerequisite for a well-functioning bioartificial kidney. In future, these supramolecular membranes allow for incorporation of peptides that may increase cell function even further. PMID: 20715132 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem Cell Microenvironments - Unveiling the Secret of How Stem Cell Fate is Defined. Macromol Biosci. 2010 Aug 16; Authors: Votteler M, Kluger PJ, Walles H, Schenke-Layland K Stem cells are defined as unspecialized cells that are capable of long term self-renewal and differentiation into specialized cell types. These unique properties make them an attractive cell source for regenerative medicine applications. Although the functions of various stem cells have been extensively studied in the development of organisms and in diseases, the specific factors and conditions that control stem cell fate, specifically the conditions that allow them to remain unspecialized, are not well studied. It has been suggested that adult stem cell survival and maintenance, as well as proliferation and differentiation, are controlled by the three-dimensional (3D) microenvironment, the so-called niche. Major functional niche components include supporting niche cells, growth-modulating soluble factors stored within the niches, and the extracellular matrix (ECM). In this article, we review work highlighting the growing complexity of stem cell-ECM interactions and their impact on the fields of biomaterials research and regenerative medicine. PMID: 20715131 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Microcarrier bioreactor culture system promotes propagation of human intervertebral disc cells. Ir J Med Sci. 2010 Aug 17; Authors: Zhang L, Ning B, Jia T, Gong W, Cong M, Chen JF, Yang SY BACKGROUND: Cell-based tissue engineering has emerged as a potential therapy for intervertebral disc degeneration. However, propagating and maintaining high quantity and quality of the seed cells remains a challenge. AIMS: To investigate the feasibility of culturing human disc cells using a microcarrier bioreactor system. METHODS: Cell counts, growth patterns, cell cycles and cellular viability were examined during the course of cell cultivation and compared between the microcarrier bioreactor culture system and the conventional monolayer culture. RESULTS: Cultures in the microcarrier bioreactor resulted in enhanced disc cell growth and satisfactory cell viability in comparison with the conventional monolayer culture. The cells in the microcarrier bioreactor cultivation exhibited higher S phase ratios, elevated mitotic index and persistent exponential growth. CONCLUSION: The microcarrier bioreactor culture system appears suitable for human disc cell propagation and may provide considerably more seeding cells for the tissue engineering process of intervertebral discs. PMID: 20714940 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Infiltration of plasma rich in growth factors for osteoarthritis of the knee short-term effects on function and quality of life. Arch Orthop Trauma Surg. 2010 Aug 17; Authors: Wang-Saegusa A, Cugat R, Ares O, Seijas R, Cuscó X, Garcia-Balletbó M PURPOSE: Osteoarthritis (OA) is a highly prevalent, chronic, degenerative condition that generates a high expense. Alternative and co-adjuvant therapies to improve the quality of life and physical function of affected patients are currently being sought. METHODS: A total of 808 patients with knee pathology were treated with PRGF (plasma rich in growth factors), 312 of them with OA of the knee (Outerbridge grades I-IV) and symptoms of >3 months duration met the inclusion criteria and were evaluated to obtain a sample of 261 patients, 109 women and 152 men, with an average age of 48.39. Three intra-articular injections of autologous PRGF were administered at 2-week intervals in outpatient surgery. The process of obtaining PRGF was carried out following the Anitua Technique. Participants were asked to fill out a questionnaire with personal data and the following assessment instruments: VAS, SF-36, WOMAC Index and Lequesne Index before the first infiltration of PRGF and 6 months after the last infiltration. RESULTS: Statistically significant differences (P < 0.0001) between pre-treatment and follow-up values were found for pain, stiffness and functional capacity in the WOMAC Index; pain and total score, distance and daily life activities in the Lequesne Index; the VAS pain score; and the SF-36 physical health domain. There were no adverse effects related to PRGF infiltration. CONCLUSION: At 6 months following intra-articular infiltration of PRGF in patients with OA of the knee, improvements in function and quality of life were documented by OA-specific and general clinical assessment instruments. These favourable findings point to consider PRGF as a therapy for OA. PMID: 20714903 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The Regenerative Potential of the Kidney: What Can We Learn from Developmental Biology? Stem Cell Rev. 2010 Aug 17; Authors: Anglani F, Mezzabotta F, Ceol M, Cristofaro R, Del Prete D, D'Angelo A Cell turnover in the healthy adult kidney is very slow but the kidney has a strong capacity for regeneration after acute injury. Although many molecular aspects of this process have been clarified, the source of the newly-formed renal epithelial cells is still being debated. Several studies have shown, moreover, that the repair of injured renal epithelium starts from mature tubular cells, which enter into an activated proliferative state characterized by the reappearance of mesenchymal markers detectable during nephrogenesis, thus pointing to a marked plasticity of renal epithelial cells. The regenerative potential of mature epithelial cells might stem from their almost unique morphogenetic process. Unlike other tubular organs, all epithelial and mesenchymal cells in the kidney derive from the same germ layer, the mesoderm. In a fascinating view of vertebrate embryogenesis, the mesoderm might be seen as a cell layer capable of oscillating between epithelial and mesenchymal states, thus acquiring a remarkable plasticity that lends it an extended potential for innovation and a better control of three-dimensional body organization. The renal papilla contains a population of cells with the characteristic of adult stem cells. Mesenchymal stromal stem cells (MSC) have been found to reside in the connective tissue of most organs, including the kidney. Recent studies indicate that the MSC compartment extends throughout the body postnatally as a result of its perivascular location. Developmental biology suggests that this might be particularly true of the kidney and that the papilla might represent the perivascular renal stem cell niche. The perivascular niche hypothesis fits well with the evolving concept of the stem cell niche as an entity of action. It is its dynamic capability that makes the niche concept so important and essential to the feasibility of regenerative medicine. PMID: 20714827 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Nanofabrication of nonfouling surfaces for micropatterning of cell and microtissue. Molecules. 2010;15(8):5525-46 Authors: Otsuka H Surface engineering techniques for cellular micropatterning are emerging as important tools to clarify the effects of the microenvironment on cellular behavior, as cells usually integrate and respond the microscale environment, such as chemical and mechanical properties of the surrounding fluid and extracellular matrix, soluble protein factors, small signal molecules, and contacts with neighboring cells. Furthermore, recent progress in cellular micropatterning has contributed to the development of cell-based biosensors for the functional characterization and detection of drugs, pathogens, toxicants, and odorants. In this regards, the ability to control shape and spreading of attached cells and cell-cell contacts through the form and dimension of the cell-adhesive patches with high precision is important. Commitment of stem cells to different specific lineages depends strongly on cell shape, implying that controlled microenvironments through engineered surfaces may not only be a valuable approach towards fundamental cell-biological studies, but also of great importance for the design of cell culture substrates for tissue engineering. To develop this kind of cellular microarray composed of a cell-resistant surface and cell attachment region, micropatterning a protein-repellent surface is important because cellular adhesion and proliferation are regulated by protein adsorption. The focus of this review is on the surface engineering aspects of biologically motivated micropatterning of two-dimensional surfaces with the aim to provide an introductory overview described in the literature. In particular, the importance of non-fouling surface chemistries is discussed. PMID: 20714311 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Parole terms for a killer: Directing caspase3/CAD induced DNA strand breaks to coordinate changes in gene expression. Cell Cycle. 2010 Aug 11;9(15) Authors: Larsen BD, Megeney LA In a series of discoveries over the preceding decade, a number of laboratories have unequivocally established that apoptotic proteins and pathways are well conserved cell fate determinants, which act independent of a cell death response. Within this context, the role for apoptotic proteins in the induction of cell differentiation has been widely documented. Despite these discoveries, little information has been forthcoming regarding a conserved mechanism by which apoptotic proteins achieve this non-death outcome. In the following discussion, we will explore the premise that the penultimate step in apoptosis, genome wide DNA damage/strand breaks act as a conserved genomic reprogramming event necessary for cell differentiation (Larsen et al. Proc Natl Acad Sci USA 2010; 107:4230-5). Moreover, we hypothesis that directed DNA damage, as mediated by known apoptotic proteins, may participate in numerous forms of regulated gene expression. PMID: 20714221 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Reconstructing neural circuits using transplanted neural stem cells in the injured spinal cord. J Clin Invest. 2010 Aug 16; Authors: Ben-Hur T Traumatic spinal cord injury is one of the most common causes of disability in young adults. Restoring independent ambulation in such patients is considered one of the biggest challenges in regenerative medicine because repair of spinal cord injury involves the complex processes of axonal regeneration, remyelination, and formation of new synaptic connections. In this issue of the JCI, Abematsu et al. report their attempts to rise to this challenge, showing in a mouse model of severe spinal cord injury that spinal neuronal circuits can be restored by neural stem cell transplantation, leading to impressive functional recovery in the hind limbs. PMID: 20714103 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Oxidative status of muscle is determined by p107 regulation of PGC-1{alpha} J Cell Biol. 2010 Aug 16; Authors: Scimé A, Soleimani VD, Bentzinger CF, Gillespie MA, Le Grand F, Grenier G, Bevilacqua L, Harper ME, Rudnicki MA Mice lacking p107 exhibit a white adipose deficiency yet do not manifest the metabolic changes typical for lipodystrophy, and instead exhibit low levels of serum triglycerides and a normal liver phenotype. When fed a high fat diet, p107-null mice still did not accumulate fat in the liver, and display markedly elevated energy expenditures together with an increased energy preference for lipids. Skeletal muscle was therefore examined, as this is normally the major tissue involved in whole body lipid metabolism. Notably, p107-deficient muscle express increased levels of peroxisome proliferator-activated receptor gamma co-activator-1alpha (PGC-1alpha) and contained increased numbers of the pro-oxidative type I and type IIa myofibers. Chromatin immunoprecipitation revealed binding of p107 and E2F4 to the PGC-1alpha proximal promoter, and this binding repressed promoter activity in transient transcription assays. Ectopic expression of p107 in muscle tissue in vivo results in a pronounced 20% decrease in the numbers of oxidative type IIa myofibers. Lastly, isolated p107-deficient muscle tissue display a threefold increase in lipid metabolism. Therefore, p107 determines the oxidative state of multiple tissues involved in whole body fat metabolism, including skeletal muscle. PMID: 20713602 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Regulation of the autophagy protein LC3 by phosphorylation. J Cell Biol. 2010 Aug 16; Authors: Cherra SJ, Kulich SM, Uechi G, Balasubramani M, Mountzouris J, Day BW, Chu CT Macroautophagy is a major catabolic pathway that impacts cell survival, differentiation, tumorigenesis, and neurodegeneration. Although bulk degradation sustains carbon sources during starvation, autophagy contributes to shrinkage of differentiated neuronal processes. Identification of autophagy-related genes has spurred rapid advances in understanding the recruitment of microtubule-associated protein 1 light chain 3 (LC3) in autophagy induction, although braking mechanisms remain less understood. Using mass spectrometry, we identified a direct protein kinase A (PKA) phosphorylation site on LC3 that regulates its participation in autophagy. Both metabolic (rapamycin) and pathological (MPP(+)) inducers of autophagy caused dephosphorylation of endogenous LC3. The pseudophosphorylated LC3 mutant showed reduced recruitment to autophagosomes, whereas the nonphosphorylatable mutant exhibited enhanced puncta formation. Finally, autophagy-dependent neurite shortening induced by expression of a Parkinson disease-associated G2019S mutation in leucine-rich repeat kinase 2 was inhibited by dibutyryl-cyclic adenosine monophosphate, cytoplasmic expression of the PKA catalytic subunit, or the LC3 phosphorylation mimic. These data demonstrate a role for phosphorylation in regulating LC3 activity. PMID: 20713600 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Human breast milk is a rich source of multipotent mesenchymal stem cells. Hum Cell. 2010 May 1;23(2):35-40 Authors: Patki S, Kadam S, Chandra V, Bhonde R Putative stem cells have been isolated from various tissue fluids such as synovial fluid, amniotic fluid, menstrual blood, etc. Recently the presence of nestin positive putative mammary stem cells has been reported in human breast milk. However, it is not clear whether they demonstrate multipotent nature. Since human breast milk is a non-invasive source of mammary stem cells, we were interested in examining the nature of these stem cells. In this pursuit, we could succeed in isolating and expanding a mesenchymal stem cell-like population from human breast milk. These cultured cells were examined by immunofluorescent labeling and found positive for mesenchymal stem cell surface markers CD44, CD29, SCA-1 and negative for CD33, CD34, CD45, CD73 confirming their identity as mesenchymal stem cells. Cytoskeletal protein marker analysis revealed that these cells expressed mesenchymal stem cells markers, namely, nestin, vimentin, smooth muscle actin and also manifests presence of E-Cadherin, an epithelial to mesenchymal transition marker in their early passages. Further we tested the multipotent differentiation potential of these cells and found that they can differentiate into adipogenic, chondrogenic and oesteogenic lineage under the influence of specific differentiation cocktails. This means that these mesenchymal stem cells isolated from human breast milk could potentially be "reprogrammed" to form many types of human tissues. The presence of multipotent stem cells in human milk suggests that breast milk could be an alternative source of stem cells for autologous stem cell therapy although the significance of these cells needs to be determined. PMID: 20712706 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Maturation State Dependent Alterations in Meniscus Integration: Implications for Scaffold Design and Tissue Engineering. Tissue Eng Part A. 2010 Aug 16; Authors: Ionescu L, Lee GC, Garcia GH, Zachry TL, Shah RP, Sennett BJ, Mauck RL The knee meniscus is a crucial component of the knee that functions to stabilize the joint, distribute load, and maintain congruency. Meniscus tears and degeneration are common, and natural healing is limited. Notably, few children present with meniscus injuries, and other related fibrocartilaginous tissues heal regeneratively in immature animals and in the fetus. In this work, we evaluated fetal, juvenile, and adult bovine meniscus properties and repair capacity in vitro. While no changes in cell behavior (migration, proliferation) were noted with age, drastic alterations in the density and distribution of the major components of meniscus tissue (proteoglycan, collagen, and DNA) occurred with development. Coincident with these marked tissue changes, the in vitro healing capacity of the tissue decreased with age. Fetal and juvenile meniscus formed a robust repair over 8 weeks on both a histological and mechanical basis, despite a lack of vascular supply. In contrast, adult meniscus did not integrate over this period. However, integration was improved significantly with the addition of growth factor TGF-beta3. Finally, to evaluate engineered scaffold integration in the context of aging, we monitored cellular infiltration from native tissue into engineered nanofibrous constructs. Our findings suggest that maturation processes that enable load bearing in the adult limit endogenous healing potential and identify new metrics for the development of tissue engineered meniscus implants. PMID: 20712419 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Modular Elastic Patches: Mechanical and Biological Effects. Biomacromolecules. 2010 Aug 16; Authors: Serban MA, Kluge JA, Laha MM, Kaplan DL A modular approach to engineering cross-linked elastic biomaterials is presented for fine-tuning of material mechanical and biological properties. The three components, soluble elastin, hyaluronic acid, and silk fibroin, contribute with different features to the overall properties of the final material system. The elastic biomaterial is chemically cross-linked via interaction between primary amine groups naturally present on the two proteins, silk and elastin, or chemically introduced on hyaluronan and N-succinimide functionalities of the cross-linker. The materials obtained by cross-linking the three components in different ratios have Young's moduli ranging from approximately 100 to 230 kPa, strain to failure between approximately 15-40% and ultimate tensile strengths of approximately 30 kPa. The biological effects and enzymatic degradation rates of the different composites are also different based on material composition. These findings further underline the strength of modular, multicomponent systems in creating a range of biomaterials, targeted tissue engineering, and regenerative medicine applications, with application-tailored mechanical and biological properties. PMID: 20712340 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Reconstructing the lung. Science. 2010 Jul 30;329(5991):520-2 Authors: Wagner WR, Griffith BP PMID: 20671176 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Generation of insulin-producing cells from gnotobiotic porcine skin-derived stem cells. Biochem Biophys Res Commun. 2010 Jul 9;397(4):679-84 Authors: Yang JH, Lee SH, Heo YT, Uhm SJ, Lee HT A major problem in the treatment of type 1 diabetes mellitus is the limited availability of alternative sources of insulin-producing cells for islet transplantation. In this study, we investigated the effect of bone morphogenetic protein 4 (BMP-4) treatments of gnotobiotic porcine skin-derived stem cells (gSDSCs) on their reprogramming and subsequent differentiation into insulin-producing cells (IPCs). We isolated SDSCs from the ear skin of a gnotobiotic pig. During the proliferation period, the cells expressed stem-cell markers Oct-4, Sox-2, and CD90; nestin expression also increased significantly. The cells could differentiate into IPCs after treatments with activin-A, glucagon-like peptide-1 (GLP-1), and nicotinamide. After 15days in the differentiation medium, controlled gSDSCs began expressing endocrine progenitor genes and proteins (Ngn3, Neuro-D, PDX-1, NKX2.2, NKX6.1, and insulin). The IPCs showed increased insulin synthesis after glucose stimulation. The results indicate that stem cells derived from the skin of gnotobiotic pigs can differentiate into IPCs under the appropriate conditions in vitro. Our three-stage induction protocol could be applied without genetic modification to source IPCs from stem cells in the skin of patients with diabetes for autologous transplantation. PMID: 20594970 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Tissue-engineered lungs for in vivo implantation. Science. 2010 Jul 30;329(5991):538-41 Authors: Petersen TH, Calle EA, Zhao L, Lee EJ, Gui L, Raredon MB, Gavrilov K, Yi T, Zhuang ZW, Breuer C, Herzog E, Niklason LE Because adult lung tissue has limited regeneration capacity, lung transplantation is the primary therapy for severely damaged lungs. To explore whether lung tissue can be regenerated in vitro, we treated lungs from adult rats using a procedure that removes cellular components but leaves behind a scaffold of extracellular matrix that retains the hierarchical branching structures of airways and vasculature. We then used a bioreactor to culture pulmonary epithelium and vascular endothelium on the acellular lung matrix. The seeded epithelium displayed remarkable hierarchical organization within the matrix, and the seeded endothelial cells efficiently repopulated the vascular compartment. In vitro, the mechanical characteristics of the engineered lungs were similar to those of native lung tissue, and when implanted into rats in vivo for short time intervals (45 to 120 minutes) the engineered lungs participated in gas exchange. Although representing only an initial step toward the ultimate goal of generating fully functional lungs in vitro, these results suggest that repopulation of lung matrix is a viable strategy for lung regeneration. PMID: 20576850 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Engineering three-dimensional collagen matrices to provide contact guidance during 3D cell migration. Curr Protoc Cell Biol. 2010 Jun;Chapter 10:Unit 10.17 Authors: Provenzano PP, Eliceiri KW, Inman DR, Keely PJ Cell invasion requires that cells navigate complex three-dimensional matrices in vivo. Topological cues are provided and three-dimensional cell migration and invasion facilitated by the alignment of collagen fibers proximal to tumors. In order to better understand the molecular mechanisms by which cells recognize and migrate along aligned matrices, in vitro assays are needed that recapitulate topological features of the in vivo matrix. Here, we describe two approaches for creating aligned three-dimensional collagen matrices, both dependent and independent of cell-mediated alignment. Approaches to quantify alignment and visualize the collagen matrix relative to the cells by second-harmonic generation are included. These assays are readily adaptable to a variety of cells and biological questions related to three-dimensional cell migration. PMID: 20521230 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Directional neurite growth using carbon nanotube patterned substrates as a biomimetic cue. Nanotechnology. 2010 Jun 11;21(23):235102 Authors: Jang MJ, Namgung S, Hong S, Nam Y Researchers have made extensive efforts to mimic or reverse-engineer in vivo neural circuits using micropatterning technology. Various surface chemical cues or topographical structures have been proposed to design neuronal networks in vitro. In this paper, we propose a carbon nanotube (CNT)-based network engineering method which naturally mimics the structure of extracellular matrix (ECM). On CNT patterned substrates, poly-L-lysine (PLL) was coated, and E18 rat hippocampal neurons were cultured. In the early developmental stage, soma adhesion and neurite extension occurred in disregard of the surface CNT patterns. However, later the majority of neurites selectively grew along CNT patterns and extended further than other neurites that originally did not follow the patterns. Long-term cultured neuronal networks had a strong resemblance to the in vivo neural circuit structures. The selective guidance is possibly attributed to higher PLL adsorption on CNT patterns and the nanomesh structure of the CNT patterns. The results showed that CNT patterned substrates can be used as novel neuronal patterning substrates for in vitro neural engineering. PMID: 20463384 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Inorganic-organic hybrid scaffolds for osteochondral regeneration. J Biomed Mater Res A. 2010 Jul;94(1):112-21 Authors: Munoz-Pinto DJ, McMahon RE, Kanzelberger MA, Jimenez-Vergara AC, Grunlan MA, Hahn MS Ligament graft failure frequently results from poor integration of the replacement tissue with associated bone. Thus, the ability to regenerate the bone-ligament osteochondral interface would be advantageous in ligament reconstruction. At the osteochondral interface, the tissue transitions from a bone-like matrix to fibrocartilage. Therefore, a scaffold which promotes a spatially regulated transition in cell behavior from osteoblast-like to chondrocyte-like would be desirable. Previous research indicates that addition of inorganic components to organic scaffolds can enhance the deposition of bone-like matrix by associated osteoblasts. We therefore reasoned that a gradient in the inorganic content of a hybrid inorganic-organic scaffold may induce an osteochondral-like transition in cell phenotype and matrix production. To test this hypothesis, hydrogels were prepared from poly(ethylene glycol) (PEG) and star poly(dimethylsiloxane) (PDMS(star)). As anticipated, both the matrix deposition and phenotype of encapsulated osteoblasts varied with scaffold inorganic content, although the directionality of this modulation was contrary to expectation. Specifically, osteoblasts appeared to transdifferentiate into chondrocyte-like cells with increasing scaffold inorganic content, as indicated by increased chondroitin sulfate and collagen type II production and by upregulation of sox9, a transcription factor associated with chondrocytic differentiation. Furthermore, the deposition of bone-like matrix (collagen type I, calcium phosphate, and osteocalcin) decreased with increasing PDMS(star) content. The resistance of the PDMS(star)-PEG scaffolds to protein adsorption and/or the changes in gel modulus/mesh structure accompanying PDMS(star) incorporation may underlie the unexpected increase in chondrocytic phenotype with increasing inorganic content. Combined, the present results indicate that PDMS(star)-PEG hybrid gels may prove promising for osteochondral regeneration. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20128006 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Growth factor-mediated effects on chondrogenic differentiation of mesenchymal stem cells in 3D semi-IPN poly(vinyl alcohol)-poly(caprolactone) scaffolds. J Biomed Mater Res A. 2010 Jul;94(1):146-59 Authors: Mohan N, Nair PD, Tabata Y Cells, signaling molecules and three-dimensional (3D) scaffolds are the major contributors to the in vitro regeneration of cartilage. This study evaluates the differentiation of mesenchymal stem cells to chondrocytes, in a 3D semi-interpenetrating polymer network (semi-IPN) scaffold that gives an appropriate niche for chondrogenic differentiation. The 3D semi-IPN scaffold poly(vinyl alcohol) and poly(caprolactone) mimics the properties of extracellular matrix of native cartilage. The chondrogenic differentiation of mesenchymal stem cells on the 3D scaffolds is carried out by supplementing signaling molecules like TGFbeta1, TGFbeta3, and BMP2 individually and in two different combinations. The results indicate that each growth factor supplement or combinations showed a different influence on cell morphology, overall distribution of cells, and secretion of cartilage specific molecules. We conclude from our results, that a combination of TGFbeta3 and BMP2 promotes better differentiation of mesenchymal stem cells to chondrocytes in our scaffold. This study hence points out that an appropriate combination of 3D scaffolds and signaling molecules are required in the differentiation and maintenance of the chondrogenic phenotype during in vitro regeneration of cartilage tissue. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20128001 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication and characterization of poly(D,L-lactide-co-glycolide)/hydroxyapatite nanocomposite scaffolds for bone tissue regeneration. J Biomed Mater Res A. 2010 Jul;94(1):137-45 Authors: Aboudzadeh N, Imani M, Shokrgozar MA, Khavandi A, Javadpour J, Shafieyan Y, Farokhi M Conventional methods in fabrication of scaffolds based on polymer/bioceramic composites frequently make use of solution casting then particle leaching. The residues of common organic solvents can get trapped in this technique hence provide safety concerns on final scaffold. In this study, N-methyl pyrrolidone was used as an approved solvent for parenteral pharmaceutical products especially implants with acceptable toxicological profile. A combined freeze drying and solvent casting methods were adopted for complete removal of the solvent from final scaffold structure. Biodegradable scaffolds based on poly (D,L-lactide-co-glycolide) and different percentages of nanohydroxyapatite (25, 35, and, 45% w/w) were characterized thoroughly regarding porosity, pore distribution as well as their bioactivity and biocompatibility. The results showed 70-80% porosity with a size distribution in the range of 50-200 mum for different conditions. Bioactivity of the scaffolds was directly dependent on the bioceramic content in the samples according to the results. Composites and neat samples showed the same cytocompatibility profile. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010. PMID: 20127996 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro astrocyte and cerebral endothelial cell response to electrospun poly(epsilon-caprolactone) mats of different architecture. J Mater Sci Mater Med. 2010 Apr;21(4):1353-62 Authors: Baiguera S, Del Gaudio C, Fioravanzo L, Bianco A, Grigioni M, Folin M This work focuses on the evaluation of the potential use of electrospun poly(epsilon-caprolactone) (PCL) micrometric and/or sub-micrometric fibrous membranes for rat hippocampal astrocyte (HA) and rat cerebro-microvascular endothelial cell (CEC) cultures. Both mats supported cell adhesion, proliferation, cellular phenotype and spreading. Microfibrous mats allowed cellular infiltration, while both HAs and CECs were unable to migrate within the sub-micrometric fibrous mat, leaving an acellularized inner region. This finding was correlated to the presence of larger voids within electrospun PCL microfibrous mats, suggesting that the morphology should be accurately selected for the realization of a cell environment-mimicking mat. Based on our results, the proper fiber architecture can be regarded as a crucial issue to be considered in order to deal with suitable polymeric mats tailored for specific in vitro application. PMID: 19957022 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A tissue adhesives evaluated in vitro and in vivo analysis. J Biomed Mater Res A. 2010 Jul;94(1):326-32 Authors: Mo X, Iwata H, Ikada Y In this study, three kinds of two-component adhesive glues were prepared, namely, gel-dext glue made from modified gelatin and dextran, gel-HES glue made from modified gelatin and hydroxyethyl starch (HES), and chit-dext glue made from chitosan and modified dextran. Upon mixing the two-component solution together crosslinking occurred and a gel formed in several seconds, which would seal the wound tissue and stop the bleeding. The adhesive ability of those three prepared glues was evaluated in vitro and in vivo separately by measuring the bonding strength to two piece of porcine skin and the adhesive strength after sealing the skin incisions on the back of rat. Fibrin glue was used as comparing. Gel-dext glue and gel-HES glue shown higher bonding strength and adhesive strength than chit-dext glue and fibrin glue. Histology test of incision tissues given by both HE and MTC methods, the former shown that gel-dext and gel-HES glues, like fibrin glue, have only normal initial inflammation to skin tissue, which almost disappear from 9 days but chit-dext glue seams have heaver inflammation, which may last to 12 days; the later shown gel-dext and gel-HES glues similar to fibrin glue, can heal the wound fast than that of chit-dext glue. The hemostatic ability for gel-HES glue was also tested on a cut liver of rat, which depend on the gel formation speed when the two-composite solutions were mixed together. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20496438 [PubMed - indexed for MEDLINE] | | | | | | | | | |  | |  | |  |
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