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| Endothelial and stem cell interactions on dielectrophoretically aligned fibrous silk fibroin-chitosan scaffolds.
February 27, 2010 at 6:37 AM
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| | Endothelial and stem cell interactions on dielectrophoretically aligned fibrous silk fibroin-chitosan scaffolds. J Biomed Mater Res A. 2010 Feb 22; Authors: Gupta V, Davis G, Gordon A, Altman AM, Reece GP, Gascoyne PR, Mathur AB Regenerative tissue engineering requires biomaterials that would mimic structure and composition of the extracellular matrix to facilitate cell infiltration, differentiation, and vascularization. Engineered scaffolds composed of natural biomaterials silk fibroin (SF) and chitosan (CS) blend were fabricated to achieve fibrillar nano-structures aligned in three-dimensions using the technique of dielectrophoresis. The effect of scaffold properties on adhesion and migration of human adipose-derived stem cells (hASC) and endothelial cells (HUVEC) was studied on SFCS (micro-structure, unaligned) and engineered SFCS (E-SFCS; nano-structure, aligned). E-SFCS constituted of a nano-featured fibrillar sheets, whereas SFCS sheets had a smooth morphology with unaligned micro-fibrillar extensions at the ends. Adhesion of hASC to either scaffolds occurred within 30 min and was higher than HUVEC adhesion. The percentage of moving cells and average speed was highest for hASC on SF! CS scaffold as compared to hASC cocultured with HUVEC. HUVEC interactions with hASC appeared to slow the speed of hASC migration (in coculture) on both scaffolds. It is concluded that the guidance of cells for regenerative tissue engineering using SFCS scaffolds requires a fine balance between cell-cell interactions that affect the migration speed of cells and the surface characteristics that affects the overall adhesion and direction of migration. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20186770 [PubMed - as supplied by publisher] | | |
| A Simple Modification of the Separation Method Reduces Heterogeneity of Adipose-Derived Stem Cells.
February 27, 2010 at 6:37 AM
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| | A Simple Modification of the Separation Method Reduces Heterogeneity of Adipose-Derived Stem Cells. Cells Tissues Organs. 2010 Feb 24; Authors: Griesche N, Luttmann W, Luttmann A, Stammermann T, Geiger H, Baer PC High hopes are put into the use of mesenchymal stem cells (MSCs) in various approaches for tissue engineering and regenerative medicine. MSCs are derived from different tissues with only small differences in their phenotype or their differentiation potential, but higher differences in the cell yield. Since fat is easily accessible and contains a high amount of MSCs to be isolated, adipose-derived stem cells (ASCs) are very promising for clinical approaches. ASCs are not a completely homogeneous cell population. Our study was initiated to explore an easy and convenient method to reduce heterogeneity. We tested different isolation methods: (1) the standard isolation method for ASCs based on plastic attachment, (2) the standard method with an initial washing step after 60 min of adherence and (3) immunomagnetic isolation by 4 typical markers (CD49a, CD90, CD105 and CD271). Cells isolated by these methods were evaluated using quantitative PCR and flow cytometry as wel! l as by their differentiation potential. Washing led to a significantly lower expression of desmin, smA and six2, and a higher expression of the stem cell markers nestin, oct-4 and sall-1, compared to standard isolated cells, while the immunomagnetically isolated cells showed no significant changes. All cells independent of the isolation method could be induced to differentiate into adipocytes and osteoblasts. Our study demonstrates that a simple washing step reduces heterogeneity of cultured ASCs according to PCR analysis, whereas the immunomagnetic isolation only showed minor advantages compared to the standard method, but the disadvantage of significantly lower cell yields in the primary isolates. PMID: 20185896 [PubMed - as supplied by publisher] | | |
| Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects.
February 27, 2010 at 6:12 AM
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| | Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects. J Orthop Res. 2010 Feb 24; Authors: Oliveira JT, Gardel LS, Rada T, Martins L, Gomes ME, Reis RL In this work, the ability of gellan gum hydrogels coupled with autologous cells to regenerate rabbit full-thickness articular cartilage defects was tested. Five study groups were defined: (a) gellan gum with encapsulated chondrogenic predifferentiated rabbit adipose stem cells (ASC + GF); (b) gellan gum with encapsulated nonchondrogenic predifferentiated rabbit adipose stem cells (ASC); (c) gellan gum with encapsulated rabbit articular chondrocytes (AC) (standard control); (d) gellan gum alone (control); (e) empty defect (control). Full-thickness articular cartilage defects were created and the gellan gum constructs were injected and left for 8 weeks. The macroscopic aspect of the explants showed a progressive increase of similarity with the lateral native cartilage, stable integration at the defect site, more pronouncedly in the cell-loaded constructs. Tissue scoring showed that ASC + GF exhibited the best results regarding tissue quality progression. Alcian blue! retrieved similar results with a better outcome for the cell-loaded constructs. Regarding real-time PCR analyses, ASC + GF had the best progression with an upregulation of collagen type II and aggrecan, and a downregulation of collagen type I. Gellan gum hydrogels combined with autologous cells constitute a promising approach for the treatment of articular cartilage defects, and adipose derived cells may constitute a valid alternative to currently used articular chondrocytes. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 20187118 [PubMed - as supplied by publisher] | | |
| Collagen type I hydrogel allows migration, proliferation, and osteogenic differentiation of rat bone marrow stromal cells.
February 27, 2010 at 6:12 AM
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| | Collagen type I hydrogel allows migration, proliferation, and osteogenic differentiation of rat bone marrow stromal cells. J Biomed Mater Res A. 2010 Feb 22; Authors: Hesse E, Hefferan TE, Tarara JE, Haasper C, Meller R, Krettek C, Lu L, Yaszemski MJ Hydrogels are potentially useful for many purposes in regenerative medicine including drug and growth factor delivery, as single scaffold for bone repair or as a filler of pores of another biomaterial in which host mesenchymal progenitor cells can migrate in and differentiate into matrix-producing osteoblasts. Collagen type I is of special interest as it is a very important and abundant natural matrix component. The purpose of this study was to investigate whether rat bone marrow stromal cells (rBMSCs) are able to adhere to, to survive, to proliferate and to migrate in collagen type I hydrogels and whether they can adopt an osteoblastic fate. rBMSCs were obtained from rat femora and plated on collagen type I hydrogels. Before harvest by day 7, 14, and 21, hydrogels were fluorescently labeled, cryo-cut and analyzed by fluorescent-based and laser scanning confocal microscopy to determine cell proliferation, migration, and viability. Osteogenic differentiation was de! termined by alkaline phosphatase activity. Collagen type I hydrogels allowed the attachment of rBMSCs to the hydrogel, their proliferation, and migration towards the inner part of the gel. rBMSCs started to differentiate into osteoblasts as determined by an increase in alkaline phosphatase activity after two weeks in culture. This study therefore suggests that collagen type I hydrogels could be useful for musculoskeletal regenerative therapies. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res 2010. PMID: 20186733 [PubMed - as supplied by publisher] | | |
| Derivation, characterization, differentiation, and registration of seven human embryonic stem cell lines (VAL-3, -4, -5, -6M, -7, -8, and -9) on human feeder.
February 27, 2010 at 6:12 AM
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| | Derivation, characterization, differentiation, and registration of seven human embryonic stem cell lines (VAL-3, -4, -5, -6M, -7, -8, and -9) on human feeder. In Vitro Cell Dev Biol Anim. 2010 Feb 26; Authors: Aguilar-Gallardo C, Poo M, Gomez E, Galan A, Sanchez E, Marques-Mari A, Ruiz V, Medrano J, Riboldi M, Valbuena D, Simon C Derivation of human embryonic stem cell lines has been a remarkable scientific achievement during the last decade. Human embryonic stem cells are regarded as an unlimited cell source for replacement therapy in regenerative medicine. Clearly, the scientific community requires proper derivation, characterization, and registration with the purpose of making them available for research and future medical applications worldwide. In this paper, we report our derivation work as the Valencian Node of the Spanish Stem Cell Bank in the generation, characterization, and registration of VAL-3, -4, -5, -6M, -7, -8, and 9 ( www.isciii/htdocs/terapia/terapia_bancocelular.jsp ). The derivation process was performed on microbiologically tested and irradiated human foreskin fibroblasts and designed to minimize contact with xeno-components in knockout Dulbecco's modified Eagle's medium supplemented with knockout serum replacement and basic fibroblast growth factor. Fingerprinting of! the cell lines was performed to allow their identification and traceability. All lines were expressed at the mRNA and specific protein markers for undifferentiation and were found to be negative for classical differentiation markers such as neurofilament heavy chain (ectoderm), renin (mesoderm), and amylase (endoderm). All lines displayed high levels of telomerase activity and were shown to successfully overcome cryopreservation and thawing. Finally, we demonstrated the potential to differentiate in vitro (embryoid body formation) and in vivo (teratoma formation) into cell types from all three germ layers. Teratoma derived from all human embryonic stem cell lines present similar morphological features except VAL-8 that display more aggressive tumor behavior with a larger proportion of solid tissues, as opposed to cyst formation in the other cell lines. PMID: 20186513 [PubMed - as supplied by publisher] | | |
| Targeting a20 decreases glioma stem cell survival and tumor growth.
February 27, 2010 at 6:12 AM
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| | Targeting a20 decreases glioma stem cell survival and tumor growth. PLoS Biol. 2010 Feb;8(2):e1000319 Authors: Hjelmeland AB, Wu Q, Wickman S, Eyler C, Heddleston J, Shi Q, Lathia JD, Macswords J, Lee J, McLendon RE, Rich JN Glioblastomas are deadly cancers that display a functional cellular hierarchy maintained by self-renewing glioblastoma stem cells (GSCs). GSCs are regulated by molecular pathways distinct from the bulk tumor that may be useful therapeutic targets. We determined that A20 (TNFAIP3), a regulator of cell survival and the NF-kappaB pathway, is overexpressed in GSCs relative to non-stem glioblastoma cells at both the mRNA and protein levels. To determine the functional significance of A20 in GSCs, we targeted A20 expression with lentiviral-mediated delivery of short hairpin RNA (shRNA). Inhibiting A20 expression decreased GSC growth and survival through mechanisms associated with decreased cell-cycle progression and decreased phosphorylation of p65/RelA. Elevated levels of A20 in GSCs contributed to apoptotic resistance: GSCs were less susceptible to TNFalpha-induced cell death than matched non-stem glioma cells, but A20 knockdown sensitized GSCs to TNFalpha-mediated ap! optosis. The decreased survival of GSCs upon A20 knockdown contributed to the reduced ability of these cells to self-renew in primary and secondary neurosphere formation assays. The tumorigenic potential of GSCs was decreased with A20 targeting, resulting in increased survival of mice bearing human glioma xenografts. In silico analysis of a glioma patient genomic database indicates that A20 overexpression and amplification is inversely correlated with survival. Together these data indicate that A20 contributes to glioma maintenance through effects on the glioma stem cell subpopulation. Although inactivating mutations in A20 in lymphoma suggest A20 can act as a tumor suppressor, similar point mutations have not been identified through glioma genomic sequencing: in fact, our data suggest A20 may function as a tumor enhancer in glioma through promotion of GSC survival. A20 anticancer therapies should therefore be viewed with caution as effects will likely differ depending on t! he tumor type. PMID: 20186265 [PubMed - in process] | | |
| A Simple Modification of the Separation Method Reduces Heterogeneity of Adipose-Derived Stem Cells.
February 27, 2010 at 6:12 AM
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| | A Simple Modification of the Separation Method Reduces Heterogeneity of Adipose-Derived Stem Cells. Cells Tissues Organs. 2010 Feb 24; Authors: Griesche N, Luttmann W, Luttmann A, Stammermann T, Geiger H, Baer PC High hopes are put into the use of mesenchymal stem cells (MSCs) in various approaches for tissue engineering and regenerative medicine. MSCs are derived from different tissues with only small differences in their phenotype or their differentiation potential, but higher differences in the cell yield. Since fat is easily accessible and contains a high amount of MSCs to be isolated, adipose-derived stem cells (ASCs) are very promising for clinical approaches. ASCs are not a completely homogeneous cell population. Our study was initiated to explore an easy and convenient method to reduce heterogeneity. We tested different isolation methods: (1) the standard isolation method for ASCs based on plastic attachment, (2) the standard method with an initial washing step after 60 min of adherence and (3) immunomagnetic isolation by 4 typical markers (CD49a, CD90, CD105 and CD271). Cells isolated by these methods were evaluated using quantitative PCR and flow cytometry as wel! l as by their differentiation potential. Washing led to a significantly lower expression of desmin, smA and six2, and a higher expression of the stem cell markers nestin, oct-4 and sall-1, compared to standard isolated cells, while the immunomagnetically isolated cells showed no significant changes. All cells independent of the isolation method could be induced to differentiate into adipocytes and osteoblasts. Our study demonstrates that a simple washing step reduces heterogeneity of cultured ASCs according to PCR analysis, whereas the immunomagnetic isolation only showed minor advantages compared to the standard method, but the disadvantage of significantly lower cell yields in the primary isolates. PMID: 20185896 [PubMed - as supplied by publisher] | | |
| Cortical plasticity induced by inhibitory neuron transplantation.
February 27, 2010 at 6:12 AM
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| | Cortical plasticity induced by inhibitory neuron transplantation. Science. 2010 Feb 26;327(5969):1145-8 Authors: Southwell DG, Froemke RC, Alvarez-Buylla A, Stryker MP, Gandhi SP Critical periods are times of pronounced brain plasticity. During a critical period in the postnatal development of the visual cortex, the occlusion of one eye triggers a rapid reorganization of neuronal responses, a process known as ocular dominance plasticity. We have shown that the transplantation of inhibitory neurons induces ocular dominance plasticity after the critical period. Transplanted inhibitory neurons receive excitatory synapses, make inhibitory synapses onto host cortical neurons, and promote plasticity when they reach a cellular age equivalent to that of endogenous inhibitory neurons during the normal critical period. These findings suggest that ocular dominance plasticity is regulated by the execution of a maturational program intrinsic to inhibitory neurons. By inducing plasticity, inhibitory neuron transplantation may facilitate brain repair. PMID: 20185728 [PubMed - in process] | | |
| Biomimetic hydrogels with pro-angiogenic properties.
February 27, 2010 at 6:12 AM
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| | Biomimetic hydrogels with pro-angiogenic properties. Biomaterials. 2010 Feb 23; Authors: Moon JJ, Saik JE, Poché RA, Leslie-Barbick JE, Lee SH, Smith AA, Dickinson ME, West JL To achieve the task of fabricating functional tissues, scaffold materials that can be sufficiently vascularized to mimic functionality and complexity of native tissues are yet to be developed. Here, we report development of synthetic, biomimetic hydrogels that allow the rapid formation of a stable and mature vascular network both in vitro and in vivo. Hydrogels were fabricated with integrin binding sites and protease-sensitive substrates to mimic the natural provisional extracellular matrices, and endothelial cells cultured in these hydrogels organized into stable, intricate networks of capillary-like structures. The resulting structures were further stabilized by recruitment of mesenchymal progenitor cells that differentiated into a smooth muscle cell lineage and deposited collagen IV and laminin in vitro. In addition, hydrogels transplanted into mouse corneas were infiltrated with host vasculature, resulting in extensive vascularization with functional blood ves! sels. These results indicate that these hydrogels may be useful for applications in basic biological research, tissue engineering, and regenerative medicine. PMID: 20185173 [PubMed - as supplied by publisher] | | |
| Conditional TGF-beta1 treatment increases stem cell-like cell population in myoblasts.
February 27, 2010 at 6:12 AM
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| | Conditional TGF-beta1 treatment increases stem cell-like cell population in myoblasts. J Cell Mol Med. 2010 Feb 23; Authors: Mu X, Li Y The limitation in successfully acquiring large populations of stem cell has impeded their application. A new method based on the dedifferentiation of adult somatic cells to generate induced multipotent stem cells would allow us to obtain a large amount of autologous stem cells for regenerative medicine. The current work was proposed to induce a sub-population of cells with characteristics of muscle stem cells from myoblasts through conditional treatment of Transforming Growth Factor (TGF)-beta1. Our results show that a lower concentration of TGF-beta1 is able to promote C2C12 myoblasts to express stem cell markers as well as to repress myogenic proteins, which involves a mechanism of dedifferentiation. Moreover, TGF-beta1 treatment promoted the proliferation-arrested C2C12 myoblasts to re-enter the S-phase. We also investigated the multi-differentiation potentials of the dedifferentiated cells. TGF-beta1 pretreated C2C12 myoblasts were implanted into mice to repai! r dystrophic skeletal muscle or injured bone. In addition to the C2C12 myoblasts, similar effects of TGF-beta1 were also observed in the primary myoblasts of mice. Our results suggest that TGF-beta1 is effective as a molecular trigger for the dedifferentiation of skeletal muscle myoblasts and could be used to generate a large pool of progenitor cells that collectively behave as multipotent stem cell-like cells for regenerative medicine applications. PMID: 20184662 [PubMed - as supplied by publisher] | | |
| The first COL7A1 mutation survey in a large Spanish Dystrophic Epidermolysis Bullosa cohort: c.6527insC disclosed as an unusually recurrent mutation.
February 27, 2010 at 6:12 AM
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| | The first COL7A1 mutation survey in a large Spanish Dystrophic Epidermolysis Bullosa cohort: c.6527insC disclosed as an unusually recurrent mutation. Br J Dermatol. 2010 Feb 22; Authors: Escámez MJ, García M, Cuadrado-Corrales N, Llames SG, Charlesworth A, De Luca N, Illera N, Sánchez-Jimeno C, Holguín A, Duarte B, Trujillo-Tiebas MJ, Vicario JL, Santiago JL, Hernández-Martín A, Torrelo A, Castiglia D, Ayuso C, Larcher F, Jorcano JL, Meana A, Meneguzzi G, Zambruno G, Del Rio M Summary Background: Dystrophic epidermolysis bullosa (DEB) is a genodermatosis caused by mutations in COL7A1. The clinical manifestations are highly variable from nail dystrophy to life-threatening blistering, making early molecular diagnosis and prognosis of utmost importance for the affected families. Mutation identification is mandatory for prenatal testing. Objective: To conduct the first mutational analysis of COL7A1 in a Spanish cohort. To assess mutation consequences at protein/mRNA level and to establish genotype-phenotype correlations. Patients/Methods: Forty-nine Spanish DEB patients were studied. Antigen mapping was performed on patient skin biopsies. COL7A1 mutation screening in genomic DNA was performed by touchdown-PCR and direct sequencing. Mutation consequences were determined by reverse transcription polymerase chain reaction (RT-PCR). Results: Eight patients belonged to three unrelated families with Dominant DEB (DDEB). Forty-one were affected wi! th Recessive DEB (RDEB). Specifically, 27 displayed the severe generalized subtype, 8 the other generalized subtype and 6 a localized phenotype (2 pretibial, 3 acral and 1 inversa). Thirty-five mutations were identified, 20 of which are novel. The pathogenic mutation c.6527insC accounted for 46.3% of RDEB Spanish alleles. A consistent genotype-phenotype correlation was established. Conclusions: Although COL7A1 database indicates that most of the DEB mutations are family specific, the pathogenic mutation c.6527insC was highly recurrent in our cohort. This level of recurrence for a single genetic defect was never reported for COL7A1. Our findings are essential to the clinicians caring for DEB patients in Spain and in the large population of Spanish descendants in Latin America. They also provide geneticists a molecular clue for a priority mutation screening strategy. PMID: 20184583 [PubMed - as supplied by publisher] | | |
| Differential gene expression in adipose stem cells cultured in allogeneic human serum versus fetal bovine serum.
February 27, 2010 at 6:12 AM
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| | Differential gene expression in adipose stem cells cultured in allogeneic human serum versus fetal bovine serum. Tissue Eng Part A. 2010 Feb 25; Authors: Lindroos B, Aho KL, Kuokkanen H, Räty S, Huhtala H, Lemponen R, Yli-Harja O, Miettinen S, Suuronen R In pre-clinical studies, human adipose stem cells (ASCs) have been shown to have therapeutic applicability, but standard expansion methods for clinical applications remain yet to be established. ASCs are typically expanded in medium containing fetal bovine serum (FBS). However, sera and other animal-derived culture reagents stage safety issues in clinical therapy, including possible infections and severe immune reactions. By expanding ASCs in medium containing human serum, the problem can be eliminated. To define how allogeneic human serum (alloHS) performs in ASC expansion compared to FBS, a comparative in vitro study in both serum supplements was performed. The choice of serum had a significant effect on ASCs. Firstly, to reach cell proliferation levels comparable with 10% FBS, at least 15% alloHS was required. Secondly, while genes of the cell cycle pathway were overexpressed in alloHS, genes of the BMP receptor mediated signaling on the TGF-beta signaling path! way, regulating e.g. osteoblast differentiation, were overexpressed in FBS. The result was further supported by differentiation analysis, where early osteogenic differentiation was significantly enhanced in FBS. The data presented here underscore the importance of thorough investigation of ASCs for utilization in cell therapies. This study is a step forward in the understanding of these potential cells. PMID: 20184435 [PubMed - as supplied by publisher] | | |
| Induction of haematopoietic differentiation of mouse embryonic stem cells by an AGM-derived stromal cell line is not further enhanced by over-expression of HOXB4.
February 27, 2010 at 6:12 AM
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| | Induction of haematopoietic differentiation of mouse embryonic stem cells by an AGM-derived stromal cell line is not further enhanced by over-expression of HOXB4. Stem Cells Dev. 2010 Feb 25; Authors: Gordon-Keylock SA, Jackson M, Huang C, Samuel K, Axton RA, Oostendorp R, Taylor AH, Wilson J, Forrester L Haematopoietic differentiation of embryonic stem (ES) cells can be enhanced by co-culture with stromal cells derived from haematopoietic tissues and by over-expression of the transcription factor HOXB4. In this study we compare the haematopoietic inductive effects of stromal cell lines derived from different sub-regions of the embryonic aorta-gonad-mesonephros tissue with the commonly used OP9 stromal cell line and with HOXB4 activation. We show that stromal cell lines derived from the aorta and surrounding mesenchyme (AM) act at an earlier stage of the differentiation process compared to bone marrow derived OP9 stromal cells. AM stromal cells were able to promote the further differentiation of isolated brachyury-GFP+ mesodermal cells into haematopoietic progenitors, whereas the OP9 stromal cells could not support the differentiation of these cells. Co-culture and analyses of individual embryoid bodies support the hypothesis that the AM stromal cell lines could en! hance the de novo production of haematopoietic progenitors, lending support to the idea that AM stromal cells might act on pre-haematopoietic mesoderm. The induction level observed for AM stromal cells was comparable to HOXB4 activation, but no additive effect was observed when these two inductive strategies were combined. Addition of a g-secretase inhibitor reduced the inductive effects of both the stromal cell line and HOXB4, providing clues to possible shared molecular mechanisms. PMID: 20184433 [PubMed - as supplied by publisher] | | |
| A survey on cell and engineered tissue therapies in Europe in 2008.
February 27, 2010 at 6:12 AM
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| | A survey on cell and engineered tissue therapies in Europe in 2008. Tissue Eng Part A. 2010 Feb 25; Authors: Martin I, Baldomero H, Tyndall A, Niederwieser D, Gratwohl A Cellular therapy is an evolving investigational treatment modality in regenerative medicine but little published information is available on its current use. Starting from the established European group for Blood and Marrow Transplantation (EBMT) activity survey on hematopoietic stem cell (HSC) transplantation, a joint committee of four major scientific organizations made a coordinated attempt to collect detailed information in Europe for the year 2008. Thirty-three teams from 16 countries reported data on 656 patients to a "novel cellular therapy" survey, which were combined to additional 384 records reported to the standard EBMT survey. Indications were cardiovascular (29%; 100% autologous), musculoskeletal (18%; 97% autologous), neurological (9%; 39% autologous), epithelial/parenchymal (9%; 18% autologous), autoimmune diseases (12%; 77% autologous) or graft-vs-host-disease (23%; 13% autologous). Reported cell types were HSC (39%), mesenchymal stromal cells (47%! ), chondrocytes (5%), keratinocytes (7%), myoblasts (2%) and others (1%). In 51% of the grafts, cells were delivered following expansion, in 4% of the cases cells were transduced. Cells were delivered intravenously (31%), intraorgan (45%), on a membrane or gel (14%) or using 3D scaffolds (10%). This data collection platform is expected to capture and foresee trends for novel cellular therapies in Europe, and warrants further consolidation and extension. PMID: 20184422 [PubMed - as supplied by publisher] | | |
| Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects.
February 27, 2010 at 6:02 AM
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| | Injectable gellan gum hydrogels with autologous cells for the treatment of rabbit articular cartilage defects. J Orthop Res. 2010 Feb 24; Authors: Oliveira JT, Gardel LS, Rada T, Martins L, Gomes ME, Reis RL In this work, the ability of gellan gum hydrogels coupled with autologous cells to regenerate rabbit full-thickness articular cartilage defects was tested. Five study groups were defined: (a) gellan gum with encapsulated chondrogenic predifferentiated rabbit adipose stem cells (ASC + GF); (b) gellan gum with encapsulated nonchondrogenic predifferentiated rabbit adipose stem cells (ASC); (c) gellan gum with encapsulated rabbit articular chondrocytes (AC) (standard control); (d) gellan gum alone (control); (e) empty defect (control). Full-thickness articular cartilage defects were created and the gellan gum constructs were injected and left for 8 weeks. The macroscopic aspect of the explants showed a progressive increase of similarity with the lateral native cartilage, stable integration at the defect site, more pronouncedly in the cell-loaded constructs. Tissue scoring showed that ASC + GF exhibited the best results regarding tissue quality progression. Alcian blue! retrieved similar results with a better outcome for the cell-loaded constructs. Regarding real-time PCR analyses, ASC + GF had the best progression with an upregulation of collagen type II and aggrecan, and a downregulation of collagen type I. Gellan gum hydrogels combined with autologous cells constitute a promising approach for the treatment of articular cartilage defects, and adipose derived cells may constitute a valid alternative to currently used articular chondrocytes. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 20187118 [PubMed - as supplied by publisher] | | |
| Extracellular matrix expression of human tenocytes in three-dimensional air-liquid and PLGA cultures compared with tendon tissue: Implications for tendon tissue engineering.
February 27, 2010 at 6:02 AM
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| | Extracellular matrix expression of human tenocytes in three-dimensional air-liquid and PLGA cultures compared with tendon tissue: Implications for tendon tissue engineering. J Orthop Res. 2010 Feb 24; Authors: Stoll C, John T, Endres M, Rosen C, Kaps C, Kohl B, Sittinger M, Ertel W, Schulze-Tanzil G Tenocyte transplantation may prove to be an approach to support healing of tendon defects. Cell-cell and cell-matrix contacts within three-dimensional (3D) cultures may prevent tenocyte dedifferentiation observed in monolayer (2D) culture. The present study compares both neotissue formation and tenocyte extracellular matrix (ECM) expression in 2D and 3D cultures directly with that of native tendon, in order to determine optimal conditions for tendon tissue engineering. Primary human tenocytes were embedded in poly[lactic-co-glycolic-acid] (PLGA)-scaffolds and high-density cultures. Neotissue formation was examined by hematoxyline-eosine (H&E) and immunofluorescence staining. Gene expression of ECM proteins and vascular endothelial growth factor (VEGF) was compared at days 0 (2D), 14, and 28 in 3D cultures and tendon. Histomorphology of 3D culture showed tendon-like tissue as tenocyte cell nuclei became more elongated and ECM accumulated. Type I collagen gene e! xpression was higher in 2D culture than in tendon and decreased in 4-week-old 3D cultures, whereas type III collagen was only elevated in high-density culture compared with tendon. Decorin and COMP were reduced in 2D and increased in 3D culture almost to ex vivo level. These results suggest that the 3D high-density or biodegradable scaffolds cultures encourage the differentiation of expanded monolayer tenocytes in vitro to tendon-like tissue. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 20187116 [PubMed - as supplied by publisher] | | |
| Age dependence of expression of growth factor receptors in porcine ACL fibroblasts.
February 27, 2010 at 6:02 AM
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| | Age dependence of expression of growth factor receptors in porcine ACL fibroblasts. J Orthop Res. 2010 Feb 22; Authors: Vavken P, Saad FA, Murray MM Tissue engineering approaches that harness the stimulatory power of platelet-rich plasma have produced encouraging results in anterior cruciate ligament (ACL) repair. However, a number of recent studies have demonstrated age-dependent differences in cellular responses to such an approach. Identifying the reasons for these differences would allow counteracting them and consequently improve outcomes. In this study we hypothesized that these age-related effects are caused by differences in the expression of the receptors for growth factors released from platelet-rich plasma (PRP). Porcine ACL fibroblasts from a predetermined number of animals of different ages were obtained, and mRNA levels of the receptors of platelet-derived growth factor (PDGF), transforming growth factor beta (TGF-beta), fibroblast growth factor (FGF), and vascular endothelial growth factor (VEGF) were determined. Expression levels were compared across age groups (young and adolescent) and regres! sed on age in days. While no significant difference was seen across groups, the regression analysis showed decreases in receptor expression with increasing age. These differences were statistically significant for TGF-beta receptor 1, FGF receptor, and VEGF receptor 2; and borderline significant for TGF-beta receptor 3 and PDGF receptor. The only receptor that was not associated with age was VEGF receptor 1, a regulator of VEGF receptor 2. These findings suggest that the decrease in growth factor receptor expression as a likely reason for reduced PRP action with increasing age. (c) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. PMID: 20186834 [PubMed - as supplied by publisher] | | |
| Calcium phosphate cement reinforcement by polymer infiltration and in situ curing: A method for 3D scaffold reinforcement.
February 27, 2010 at 6:02 AM
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| | Calcium phosphate cement reinforcement by polymer infiltration and in situ curing: A method for 3D scaffold reinforcement. J Biomed Mater Res A. 2010 Feb 22; Authors: Alge DL, Chu TM This study describes a novel method of calcium phosphate cement reinforcement based on infiltrating a pre-set cement with a reactive polymer and then cross-linking the polymer in situ. This method can be used to reinforce 3D calcium phosphate cement scaffolds, which we demonstrate using poly(ethylene glycol) diacrylate (PEGDA) as a model reinforcing polymer. The compressive strength of a 3D scaffold comprised of orthogonally intersecting beams was increased from 0.31 +/- 0.06 MPa to 1.65 +/- 0.13 MPa using PEGDA 600. In addition, the mechanical properties of reinforced cement were characterized using three PEGDA molecular weights (200, 400, and 600 Da) and three cement powder to liquid (P/L) ratios (0.8, 1.0, and 1.43). Higher molecular weight increased reinforcement efficacy, and P/L controlled cement porosity and determined the extent of polymer incorporation. Although increasing polymer incorporation resulted in a transition from brittle, cement-like behavior t! o ductile, polymer-like behavior, maximizing polymer incorporation was not advantageous. Polymerization shrinkage produced microcracks in the cement, which reduced the mechanical properties. The most effective reinforcement was achieved with P/L of 1.43 and PEGDA 600. In this group, flexural strength increased from 0.44 +/- 0.12 MPa to 7.04 +/- 0.51 MPa, maximum displacement from 0.05 +/- 0.01 mm to 1.44 +/- 0.17 mm, and work of fracture from 0.64 +/- 0.10 J/m(2) to 677.96 +/- 70.88 J/m(2) compared to non-reinforced controls. These results demonstrate the effectiveness of our novel reinforcement method, as well as its potential for fabricating reinforced 3D calcium phosphate cement scaffolds useful for bone tissue engineering. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20186776 [PubMed - as supplied by publisher] | | |
| Endothelial and stem cell interactions on dielectrophoretically aligned fibrous silk fibroin-chitosan scaffolds.
February 27, 2010 at 6:02 AM
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| | Endothelial and stem cell interactions on dielectrophoretically aligned fibrous silk fibroin-chitosan scaffolds. J Biomed Mater Res A. 2010 Feb 22; Authors: Gupta V, Davis G, Gordon A, Altman AM, Reece GP, Gascoyne PR, Mathur AB Regenerative tissue engineering requires biomaterials that would mimic structure and composition of the extracellular matrix to facilitate cell infiltration, differentiation, and vascularization. Engineered scaffolds composed of natural biomaterials silk fibroin (SF) and chitosan (CS) blend were fabricated to achieve fibrillar nano-structures aligned in three-dimensions using the technique of dielectrophoresis. The effect of scaffold properties on adhesion and migration of human adipose-derived stem cells (hASC) and endothelial cells (HUVEC) was studied on SFCS (micro-structure, unaligned) and engineered SFCS (E-SFCS; nano-structure, aligned). E-SFCS constituted of a nano-featured fibrillar sheets, whereas SFCS sheets had a smooth morphology with unaligned micro-fibrillar extensions at the ends. Adhesion of hASC to either scaffolds occurred within 30 min and was higher than HUVEC adhesion. The percentage of moving cells and average speed was highest for hASC on SF! CS scaffold as compared to hASC cocultured with HUVEC. HUVEC interactions with hASC appeared to slow the speed of hASC migration (in coculture) on both scaffolds. It is concluded that the guidance of cells for regenerative tissue engineering using SFCS scaffolds requires a fine balance between cell-cell interactions that affect the migration speed of cells and the surface characteristics that affects the overall adhesion and direction of migration. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20186770 [PubMed - as supplied by publisher] | | | | 
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