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| No Ten Year 'Sunset' on CIRM Horizon
February 12, 2010 at 12:36 AM
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| California's unprecedented, $3 billion stem cell research program is widely perceived as a 10-year effort, but, like much conventional wisdom, that view is simply wrong.
The agency, created as the result of a 2004 political campaign, theoretically could continue to function for eons. The only relatively immediate, "life-and-death" question facing CIRM involves the cash needed to continue its | | |
| Statement on CIRM's Life Span From the Agency's Counsel
February 12, 2010 at 12:15 AM
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| Here is the text of the statement to the California Stem Cell Report from James Harrison of Remcho, Johansen & Purcell of San Leandro, Ca., CIRM's outside counsel, on the life expectancy of the stem cell agency.
"We wrote Prop. 71 to protect the voters' mandate against ideologically motivated litigation that could deny Californians the opportunity to have ten full years of medical and | | |
| Stem cells in cardiac repair in an inflammatory microenvironment.
February 11, 2010 at 8:06 AM
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| | Stem cells in cardiac repair in an inflammatory microenvironment. Minerva Cardioangiol. 2010 Feb;58(1):127-146 Authors: Rameshwar P, Qiu H, Vatner SF Despite advances in clinical interventions, drug therapy and preventative strategies for cardiovascular disease, heart disease remains the number one cause of death in the United States. A major cause of heart failure leading to death is myocardial ischemic disease. Terminal heart failure can be salvaged in some cases by cardiac transplants, but this therapeutic approach is limited by lack of supply, high cost, and problems with immunosuppression. An attractive alternative approach proposed over the last 1-2 decades is the replacement of myocardium at the level of the myocyte, which has focused on stem cell therapy. This form of therapy has been successful for hematopoietic replacement. Similar therapy has been proposed to treat hearts ravaged by ischemic necrosis and apoptosis. However, the experimental studies have not been effectively translated to patients with myocardial infarction or heart failure. This review discusses the current literature and points out ! key studies that are required for future directions, focusing on key roles for microenvironmental factors, such as cytokines, in stem cells responses when placed at sites of cardiac injuries. In the case of mesenchymal stem cells (MSCs), they exert both immune- enhancer and -suppressor functions, which are referred to as immune plasticity. This type of immune properties by MSCs is significant to therapeutic outcomes. Thus, the plasticity of MSCs, with regards to immune responses, has to be considered carefully in tissue repair and replacement and in gene delivery systems. The route by which cytokines are delivered as adjuvant to cell therapy, or as methods to mobilize stem cells, will show varied results, depending on the degree of injury, underlying clinical disorders and other diverse parameters, such as ethnicity, age and genomic profile. In addition to MSCs, roles exist for other stem cells, such as those from placenta, cord blood, hematopoietic stem/progenitor cells an! d cardiac stem cells. PMID: 20145600 [PubMed - as supplied by publisher] | | |
| TGF-beta and Notch Signaling Mediate Stem Cell Differentiation into Smooth Muscle Cells.
February 11, 2010 at 7:01 AM
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| | TGF-beta and Notch Signaling Mediate Stem Cell Differentiation into Smooth Muscle Cells. Stem Cells. 2010 Feb 9; Authors: Kurpinski K, Lam H, Chu J, Wang A, Kim A, Tsay E, Agrawal S, Schaffer D, Li S The differentiation of stem cells into smooth muscle cells (SMCs) plays an important role in vascular development and remodeling. In addition, stem cells represent a potential source for generating SMCs for regenerative medicine applications such as constructing vascular grafts. Previous studies have suggested that various biochemical factors including transforming growth factor-beta (TGF-beta) and the Notch pathway may play important roles in vascular differentiation. However, the interactions of these two signaling pathways in the differentiation of bone marrow mesenchymal stem cells (MSCs) have not been clearly defined. In this study, we profiled the gene expression in MSCs in response to TGF-beta, and showed that TGF-beta induced Notch ligand JAG1 (JAG1) and SMC markers including smooth muscle alpha-actin (SM-actin), calponin 1 (CNN1), and myocardin (MYCD), which were dependent on the activation of SMAD3 and Rho kinase. In addition, knocking down JAG1 expressi! on partially blocked SM-actin and CNN1 expression and completely blocked MYCD expression, suggesting that JAG1 plays an important role in TGF-beta-induced expression of SMC markers. Furthermore, the activation of Notch signaling resulted in the expression of SMC markers in MSCs, and the activation of Notch signaling in human embryonic stem cells induced the expression of SMC and neural markers but inhibited the expression of endothelial markers. These results suggest that Notch signaling mediates TGF-beta regulation of MSC differentiation and that Notch signaling induces the differentiation of MSCs and hESCs into SMCs, which represents a novel mechanism involved in stem cell differentiation. PMID: 20146266 [PubMed - as supplied by publisher] | | |
| lacZ as a genetic reporter for real-time MRI.
February 11, 2010 at 7:01 AM
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| | lacZ as a genetic reporter for real-time MRI. Magn Reson Med. 2010 Feb 9; Authors: Bengtsson NE, Brown G, Scott EW, Walter GA Molecular imaging based on MRI is currently hampered by the lack of genetic reporters for in vivo imaging. We determined that the commercially available substrate S-Gal can be used to detect genetically engineered beta-galactosidase expressing cells by MRI. The effect and specificity of the reaction between beta-galactosidase and S-Gal on MRI contrast were determined both in vitro and in vivo. beta-galactosidase activity in the presence of S-Gal resulted in enhanced T(2) and T*(2) MR-contrast, which was amplified with increasing magnetic field strengths (4.7-17.6 T) in phantom studies. Using both lacZ(+) transgenic animals and lacZ(+) tissue transplants, we were able to detect labeled cells in live animals in real time. Similar to phantom studies, detection of the labeled cells/tissues in vivo was enhanced at high magnetic fields. These results demonstrate that the genetic reporter, lacZ, can be used as an in vivo marker gene using high-field-strength MRI. Magn Re! son Med, 2010. (c) 2010 Wiley-Liss, Inc. PMID: 20146234 [PubMed - as supplied by publisher] | | |
| Calcium-alginate microcapsules with spherical liquid cores templated by gelatin microparticles for mass production of multicellular spheroids.
February 11, 2010 at 7:01 AM
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| | Calcium-alginate microcapsules with spherical liquid cores templated by gelatin microparticles for mass production of multicellular spheroids. Acta Biomater. 2010 Feb 6; Authors: Sakai S, Ito S, Kawakami K Multicellular spheroids are important in biomedical applications, such as drug research and regenerative medicine. We developed microcapsules from sodium-alginate and gelatin for mass production of size-controlled spheroids with diameters < 200 mum. The microcapsules were composed of Ca-alginate gels with spherical liquid cores (diameter approximately 150 mum) for formation of spheroids. The spherical liquid cores were prepared by incubating Ca-alginate microcapsules containing thermally gelled, cell-enclosing gelatin microparticles about 150 mum in diameter, at 37 degrees C. The gelatin microparticles were encapsulated within the microcapsules by dropping a sodium-alginate solution containing suspended gelatin microparticles into 100 mM CaCl(2). The enclosed feline renal fibroblast cell line, CRFK, cells showed 93.8% viability immediately after encapsulation, then grew and completely filled the spherical cores. Multicellular spheroids were collected within 1 m! in by soaking microcapsules in a medium containing alginate lyase. PMID: 20144915 [PubMed - as supplied by publisher] | | |
| Sprouty1 Regulates Reversible Quiescence of a Self-Renewing Adult Muscle Stem Cell Pool during Regeneration.
February 11, 2010 at 7:01 AM
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| | Sprouty1 Regulates Reversible Quiescence of a Self-Renewing Adult Muscle Stem Cell Pool during Regeneration. Cell Stem Cell. 2010 Feb 5;6(2):117-129 Authors: Shea KL, Xiang W, Laporta VS, Licht JD, Keller C, Basson MA, Brack AS Satellite cells are skeletal muscle stem cells capable of self-renewal and differentiation after transplantation, but whether they contribute to endogenous muscle fiber repair has been unclear. The transcription factor Pax7 marks satellite cells and is critical for establishing the adult satellite cell pool. By using a lineage tracing approach, we show that after injury, quiescent adult Pax7(+) cells enter the cell cycle; a subpopulation returns to quiescence to replenish the satellite cell compartment, while others contribute to muscle fiber formation. We demonstrate that Sprouty1 (Spry1), a receptor tyrosine kinase signaling inhibitor, is expressed in quiescent Pax7(+) satellite cells in uninjured muscle, downregulated in proliferating myogenic cells after injury, and reinduced as Pax7(+) cells re-enter quiescence. We show that Spry1 is required for the return to quiescence and homeostasis of the satellite cell pool during repair. Our results therefore define a ! role for Spry1 in adult muscle stem cell biology and tissue repair. PMID: 20144785 [PubMed - as supplied by publisher] | | |
| Stem Cells and the Niche: A Dynamic Duo.
February 11, 2010 at 7:01 AM
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| | Stem Cells and the Niche: A Dynamic Duo. Cell Stem Cell. 2010 Feb 5;6(2):103-115 Authors: Voog J, Jones DL Stem cell niches are dynamic microenvironments that balance stem cell activity to maintain tissue homeostasis and repair throughout the lifetime of an organism. The development of strategies to monitor and perturb niche components has provided insight into the responsive nature of the niche and offers a framework to uncover how disruption of normal stem cell niche function may contribute to aging and disease onset and progression. Additional work in the identification of genetic factors that regulate the formation, activity, and size of stem cell niches will facilitate incorporation of the niche into stem cell-based therapies and regenerative medicine. PMID: 20144784 [PubMed - as supplied by publisher] | | |
| Hydrated xenogeneic decellularized tracheal matrix as a scaffold for tracheal reconstruction.
February 11, 2010 at 7:01 AM
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| | Hydrated xenogeneic decellularized tracheal matrix as a scaffold for tracheal reconstruction. Biomaterials. 2010 Feb 6; Authors: Remlinger NT, Czajka CA, Juhas ME, Vorp DA, Stolz DB, Badylak SF, Gilbert S, Gilbert TW Tracheal injury is a rare but complex problem. Primary tracheal reconstructions are commonly performed, but complications such as tension and inadequate vascular supply limit the length of surgical resection. The objective of the present study was to determine whether a hydrated, decellularized porcine tracheal extracellular matrix showed the potential to serve as a functional tracheal replacement graft. Porcine tracheas were decellularized and evaluated to characterize their biochemical composition and biomechanical behavior. Hydrated decellularized tracheal matrix (HDTM) grafts (>5 cm) were implanted heterotopically beneath the strap muscle and wrapped in the omentum in a canine model for 2 and 8 weeks followed by histologic and mechanical analysis. HDTM patches (2 x 3 cm) were also used in a patch tracheoplasty model. The repair site was evaluated bronchoscopically and radiographically, and the grafts were analyzed by histologic methods to evaluate epithelia! lization and persistence of the cartilage rings. The present study showed that HDTM maintains mechanical characteristics necessary for function under physiologic loading conditions even after 8 weeks of heterotopic implantation. After orthotopic implantation, the grafts were shown to support development of a columnar, pseudostratified, ciliated epithelium, but the cartilage structures showed histologic evidence of degradation and limited new cartilage formation. The results of the study showed tracheal ECM scaffolds support the formation of site-specific epithelium and provide sufficient mechanical integrity withstand physiologic pressures in the short-term. However, for long-term success, it appears that pre-implantation to allow vascularization or preseeding of the graft with chondrocytes will be necessary. PMID: 20144481 [PubMed - as supplied by publisher] | | |
| The healing of critical-sized femoral segmental bone defects in rabbits using baculovirus-engineered mesenchymal stem cells.
February 11, 2010 at 7:01 AM
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| | The healing of critical-sized femoral segmental bone defects in rabbits using baculovirus-engineered mesenchymal stem cells. Biomaterials. 2010 Feb 6; Authors: Lin CY, Chang YH, Lin KJ, Yen TC, Tai CL, Chen CY, Lo WH, Hsiao IT, Hu YC Management of massive segmental bone defects remains a challenging clinical problem and bone marrow-derived mesenchymal stem cells (BMSCs) hold promise for bone regeneration. To explore whether BMSCs engineered by baculovirus (an emerging gene delivery vector) can heal large bone defects, New Zealand White (NZW) rabbit BMSCs were transduced with the BMP2-expressing baculovirus or VEGF-expressing baculovirus, and co-implanted into critical-sized (10mm) femoral segmental defects in NZW rabbits. X-ray analysis revealed that the baculovirus-engineered BMSCs not only bridged the defects at as early as week 2, but also healed the defects in 100% of rabbits (13/13) at week 4. The osteogenic metabolism, as monitored by positron emission tomography (PET) also suggested the completion of bone healing at week 8. When compared with other control groups, the BMP2/VEGF-expressing BMSCs remarkably enhanced the segmental bone repair and mechanical properties, as evidenced by micr! o-computed tomography (muCT), histochemical staining and biomechanical testing. The ameliorated bone healing concurred with the augmented angiogenesis. These data demonstrated, that BMSCs engineered to express BMP2 and VEGF accelerate the repair of large femoral bone defects and improve the quality of the regenerated bone, which paves an avenue to utilizing baculovirus as a vector for BMSCs modification and regenerative medicine. PMID: 20144476 [PubMed - as supplied by publisher] | | |
| Mechanical and Microstructural Properties of Polycaprolactone Scaffolds with 1-D, 2-D, and 3-D Orthogonally Oriented Porous Architectures Produced by Selective Laser Sintering.
February 11, 2010 at 6:31 AM
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| | Mechanical and Microstructural Properties of Polycaprolactone Scaffolds with 1-D, 2-D, and 3-D Orthogonally Oriented Porous Architectures Produced by Selective Laser Sintering. Acta Biomater. 2010 Feb 6; Authors: Eshraghi S, Das S This article reports on the experimental determination and finite element modeling of tensile and compressive mechanical properties of solid polycaprolactone (PCL) and of porous PCL scaffolds with 1-D, 2-D and 3-D orthogonal, periodic porous architectures produced by selective laser sintering (SLS). PCL scaffolds were built using optimum processing parameters ensuring scaffolds with nearly full density (>95%) in the designed solid regions and with excellent geometric and dimensional control (within 3-8% of design). The tensile strength of bulk PCL ranged from 10.5-16.1 MPa, its modulus ranged from 343.9-364.3 MPa, and the tensile yield strength ranged from 8.2-10.1MPa. These values are consistent with reported literature values for PCL processed through various manufacturing methods. Across porosity ranging from 56.87-83.3%, the tensile strength ranged from 4.5-1.1 MPa, the tensile modulus ranged from 140.5-35.5 MPa, and the yield strength ranged from 3.2-0.76 ! MPa. The compressive strength of bulk PCL was 38.7 MPa, the compressive modulus ranged from 297.8-317.1 MPa, and the compressive yield strength ranged from 10.3-12.5MPa. Across porosity ranging from 51.1-80.9%, the compressive strength ranged from 10.0-0.6 MPa, the compressive modulus ranged from 14.9-12.1 MPa, and the compressive yield strength ranged from 4.25-0.42 MPa. These values while being in the lower range of reported values for trabecular bone, are the highest reported for PCL scaffolds produced by SLS and are among the highest reported for similar PCL scaffolds produced through other layered manufacturing techniques. Finite element analysis showed good agreement between experimental and computed effective tensile and compressive moduli. Thus, the construction of bone tissue engineering scaffolds endowed with oriented porous architectures and with predictable mechanical properties through SLS is demonstrated. PMID: 20144914 [PubMed - as supplied by publisher] | | |
| Influence of Polymer Content in Ca-deficient Hydroxyapatite-Polycaprolactone (CDHA-PCL) Nanocomposites on the Formation of Microvessel-like Structures.
February 11, 2010 at 6:31 AM
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| | Influence of Polymer Content in Ca-deficient Hydroxyapatite-Polycaprolactone (CDHA-PCL) Nanocomposites on the Formation of Microvessel-like Structures. Acta Biomater. 2010 Feb 6; Authors: Fuchs S, Jiang X, Gotman I, Makarov C, Schmidt H, Gutmanas EY, Kirkpatrick CJ Calcium Phosphate (CaP) ceramics are widely used in bone tissue engineering due to their good osteoconductivity. The mechanical properties of CaP can be modified by addition of small volume fractions of biodegradable polymer such as polycaprolactone (PCL). Nevertheless, it is also important to evaluate how the polymer content influences cell-material or cell-cell interactions on account of potential consequences for bone regeneration and vascularization. In this study we assessed the general biocompatibilty of Ca-deficient hydroxyapatite (CDHA)-PCL disks containing nominally 11% and 24% polycaprolactone using human umbilical vein endothelial cells and human primary osteoblasts. Confocal microscopy showed that both CDHA -PCL variants supported the growth of both cell types. In terms of the endothelial cells grown on CDHA-PCL nano-composites with 24% PCL an increased expression of the endothelial markers vWF compared to CDHA-PCL with 11% PCL was observed in real-tim! e PCR analysis. In addition to monocultures co-cultures of outgrowth endothelial cells, derived from peripheral blood, and primary osteoblasts were assessed as an example of a more complex test system for bone regeneration and vascularization. Constructs based on CDHA with different PCL contents were investigated with regard to the formation of microvessel-like structures induced by the co-culture process using confocal microscopy and quantitative image analysis. Furthermore, the osteogenic differentiation of the co-culture was assessed. As a result more pre-vascular structures were observed after 1 week on CDHA-PCL disks with 24% polycaprolactone, whereas after 4 weeks of culture the extent of microvessel-like structure formation was slightly higher on CDHA with 11% PCL. In contrast to this, variation of PCL content had no effect on the osteogenic differentiation in the co-culture. PMID: 20144913 [PubMed - as supplied by publisher] | | |
| Essential modification of the Sircol Collagen Assay for the accurate quantification of collagen content in complex protein solutions.
February 11, 2010 at 6:31 AM
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| | Essential modification of the Sircol Collagen Assay for the accurate quantification of collagen content in complex protein solutions. Acta Biomater. 2010 Feb 5; Authors: Lareu RR, Zeugolis DI, Abu-Rub M, Pandit A, Raghunath M Collagen contains the unique imino acid hydroxyproline (HyPro) that is involved in the stabilisation of this triple helical molecule. The concentration of HyPro is customarily used to calculate the total collagen content in cell culture environment and in acid hydrolysates of normal and pathophysiological tissues. Radio-labelling, chromatographic and calorimetric assays have been developed over the years for the accurate determination of collagen content through HyPro estimation. Recently, the Sircol Collagen Assay (SCA) has been almost exclusively adopted as the fastest and simplest colorimetric method for the determination of collagen concentration in complex protein solutions. We show here that the colorimetric SCA, which is based on the binding of Sirius red (SR) to collagen, is flawed by interference of non-collagenous proteins (e.g. serum). In fact, we demonstrate that SCA in cell culture systems and tissue hydrolysates results in a dramatic overestimation o! f collagen content ranging from 3- to 24- fold. In order to rescue this otherwise very practical assay, we introduce a simple purification procedure that allows the removal of interfering non-collagenous proteins from culture media and tissue samples so that accurate measurements with SCA are now possible. PMID: 20144751 [PubMed - as supplied by publisher] | | |
| Impact of nanopore morphology on cell viability on mesoporous polymer and carbon surfaces.
February 11, 2010 at 6:31 AM
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| | Impact of nanopore morphology on cell viability on mesoporous polymer and carbon surfaces. Acta Biomater. 2010 Feb 5; Authors: Chavez VL, Song L, Barua S, Li X, Wu Q, Zhao D, Rege K, Vogt BD Topology at the nanoscale can lead to dramatic changes in the adhesion and viability of cells to surfaces. For biological applications, including tissue engineering and cell-based sensing, the large internal surface area of ordered mesoporous carbons provides an opportunity for enhanced sensitivity and performance, but the mesostructure also impacts the topology of the material. In this work, we probe the viability and adhesion of osteoblasts on ordered mesoporous materials with different morphology and matrix chemistry. FDU-15 (hexagonal) and FDU-16 (cubic) films are processed at either 350 degrees C (polymeric) or 800 degrees C (carbon) to provide these different materials. For the films processed at 350 degrees C, the cell adhesion is markedly improved on the mesoporous films in comparison to a dense film analog, consistent with many reports in the literature that nanostructuring of surfaces improves the viability and adhesion of osteoblasts. Conversely, osteob! last adhesion decreases on the carbonized surfaces processed at 800 degrees C when ordered mesopores are introduced, particularly for the cubic mesostructure (FDU-16). We attribute the decrease in cell adhesion to the propensity of the ordered mesoporous carbons to sorb organics from aqueous solution, which could lead to removal of adhesion promoting compounds at the film surface. These results suggest that cell viability on mesoporous polymer and carbon films can be controlled through simple changes in the pyrolysis temperature. PMID: 20144750 [PubMed - as supplied by publisher] | | |
| Preparation, characterization and in vitro analysis of novel structured nanofibrous scaffolds for bone tissue engineering.
February 11, 2010 at 6:31 AM
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| | Preparation, characterization and in vitro analysis of novel structured nanofibrous scaffolds for bone tissue engineering. Acta Biomater. 2010 Feb 5; Authors: Wang J, Yu X In the previous study, we have developed a 3D nanofibrous spiral scaffold for bone tissue engineering which has shown enhanced human osteoblast cell attachment, proliferation and differentiation compared to traditional cylinder scaffolds due to the spiral structures and the nanofiber incorporation. However, these scaffolds were limited by the weak mechanical strength for the application to bone tissue engineering. This limitation triggered the design for novel structured scaffolds with reinforced physical characteristics. In this study, the spiral Polycaprolactone (PCL) nanofibrous scaffolds were inserted into Poly(lactide-co-glycolide) (PLGA) microsphere sintered tubular scaffolds to form integrated scaffolds for providing appropriate mechanical property and bioactivity for bone tissue engineering. Four experiment groups were designed: PLGA cylinder scaffold; PLGA tubular scaffold; PLGA tubular scaffold with PCL spiral structured inner core; PLGA tubular scaffold! with PCL nanofiber containing spiral structured inner core. The morphology, porosity and mechanical properties of the scaffolds were characterized. Furthermore, human osteoblastic cells were seeded on these scaffolds and cell attachment, proliferation, differentiation and mineralized matrix deposition on the scaffolds were evaluated. The integrated scaffolds had a Young's modulus 250-300MPa, and compressive strength 8-11MPa under uniaxial compression . With the addition of inner highly porous insert to the tubular shell, human osteoblast cells seeded on the integrated scaffolds showed slightly higher cell proliferation, 20% -25% more alkaline phosphtotase expression and 2 folds higher calcium deposition than those the cylinder and tubular scaffolds. Furthermore, compare to the sintered PLGA cylinder scaffolds, the integrated scaffolds allow better cellular infiltration Therefore, this design demonstrates great potential of these integrated scaffolds for bone tissue enginee! ring applications. PMID: 20144749 [PubMed - as supplied by publisher] | | |
| Maxillary sinus floor elevation using a tissue engineered bone complex with BMP-2 gene modified bMSCs and a novel porous ceramic scaffold in rabbits.
February 11, 2010 at 6:31 AM
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| | Maxillary sinus floor elevation using a tissue engineered bone complex with BMP-2 gene modified bMSCs and a novel porous ceramic scaffold in rabbits. Arch Oral Biol. 2010 Feb 6; Authors: Sun XJ, Xia LG, Chou LL, Zhong W, Zhang XL, Wang SY, Zhao J, Jiang XQ, Zhang ZY OBJECTIVES: To study the effects of maxillary sinus floor elevation by a tissue engineered bone complex with bone morphogenetic protein-2 (BMP-2) gene modified bone marrow stromal cells (bMSCs) and a novel porous ceramic scaffold (OsteoBone) in rabbits. MATERIALS AND METHODS: bMSCs derived from New Zealand rabbit bone marrow were cultured and transduced with adenovirus AdBMP-2 and with AdEGFP gene (without BMP-2 gene sequence) as a control, respectively, in vitro. These bMSCs were then combined with OsteoBone scaffold at a concentration of 2x10(7)cells/ml and used to elevate the maxillary sinus floor in rabbits. Eight rabbits were randomly allocated into groups and sacrificed at weeks 2 and 4. For each time point, 8 maxillary sinus floor elevation surgeries were made bilaterally in 4 rabbits for the two groups (n=4 per group): group A (AdBMP-2-bMSCs/material) and group B (AdEGFP-bMSCs/material). All samples were evaluated by histologic and histomorphometric analys! is. RESULTS: The augmented maxillary sinus height was maintained for both groups over the entire experimental period, while new bone area increased over time for group A. At week 4 after operation, bone area in group A was significantly more than that in group B (P<0.05), and was more obviously detected in the center of the elevated space. Under a confocal microscope, green fluorescence in newly formed bone was observed in the EGFP group, which suggests that those implanted bMSCs had contributed to the new bone formation. CONCLUSION: bMSCs modified with AdBMP-2 gene can promote new bone formation in elevating the rabbit maxillary sinus. OsteoBone scaffold could be an ideal carrier for gene enhanced bone tissue engineering. PMID: 20144455 [PubMed - as supplied by publisher] | | |
| Effects of hyperinsulinemia on lipolytic function of three-dimensional adipocyte/endothelial co-cultures.
February 11, 2010 at 6:31 AM
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| | Effects of hyperinsulinemia on lipolytic function of three-dimensional adipocyte/endothelial co-cultures. Tissue Eng Part C Methods. 2010 Feb 9; Authors: Choi J, Gimble J, Vunjak-Novakovic G, Kaplan DL The increased incidence of both type 2 diabetes mellitus (T2DM) and obesity has prompted the need to develop physiologically relevant adipose tissue models for controlled study of both normal and diseased adipose functions. Insulin resistance, characteristic of both T2DM and obesity, is often preceded by hyperinsulinemia. We propose here a three-dimensional (3D) co-culture adipose tissue model to study the effects of high insulin exposure, which enabled the study of physiological cell responses to hyperinsulinemic conditions. Two-dimensional (2D) adipocyte studies were initially conducted to establish a baseline control in which insulin levels were established. Adipocytes and endothelial cells were subsequently co-cultured on 3D porous silk fibroin scaffolds in normal or high insulin concentrations, and their physiological responses were assessed with respect to lipogenesis and lipolysis. High insulin levels stimulated both an increase in triglyceride accumulation! and a decrease in lipolysis levels compared to that of normal insulin conditions. In contrast, adipocyte monocultures did not exhibit any differences between insulin levels. The ability of this 3D system to elicit physiological responses to hyperinsulinemia in co-culture, serves as a significant step forward in adipose tissue engineering. The development of physiologically relevant 3D in vitro adipose tissue models presents promise for the study of disease mechanisms as well as in assessing therapeutic treatments. PMID: 20144013 [PubMed - as supplied by publisher] | | |
| Translational studies in anterior cruciate ligament repair.
February 11, 2010 at 6:31 AM
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| | Translational studies in anterior cruciate ligament repair. Tissue Eng Part B Rev. 2010 Feb;16(1):5-11 Authors: Vavken P, Murray MM Translational research, which can be explained as the principle of combining advances in both basic research and clinical understanding in a bedside-to-bench-to-bedside approach, has become one of the central themes of present-day medical research. One orthopedic problem that has strongly benefited from such an approach is tissue-engineering-enhanced primary repair of the anterior cruciate ligament. Recent years have shown a clearer definition of the clinical problem and established an underlying mechanistic cause of the incapacity of the anterior cruciate ligament to heal-the premature loss of provisional scaffold in the wound site. These clinical findings were then translated into a research objective, namely, to replace the missing scaffold with a biomaterial with appropriate structural and bio-stimulatory characteristics. Subsequently, a tissue-engineering-based treatment using a collagen-platelet composite was developed and tested in vitro. After proofing the! efficacy of this new treatment in the laboratory, it was translated into a potential clinical application, which showed highly successful results in structural integrity and biomechanical capacity in large animal testing. This approach of defining the scientific mechanism underlying a clinical observation and then using that information to design new therapies is but one example of how translational research in tissue engineering can help define and develop new treatments for challenging problems faced by patients. PMID: 20143926 [PubMed - in process] | | |
| Microbioreactors for Raman Microscopy of Stromal Cell Differentiation.
February 11, 2010 at 6:31 AM
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| | Microbioreactors for Raman Microscopy of Stromal Cell Differentiation. Anal Chem. 2010 Feb 9; Authors: Pully VV, Lenferink A, van Manen HJ, Subramaniam V, van Blitterswijk CA, Otto C We present the development of microbioreactors with a sensitive and accurate optical coupling to a confocal Raman microspectrometer. We show that such devices enable in situ and in vitro investigation of cell cultures for tissue engineering by chemically sensitive Raman spectroscopic imaging techniques. The optical resolution of the Raman microspectrometer allows recognition and chemical analysis of subcellular features. Human bone marrow stromal cells (hBMSCs) have been followed after seeding through a phase of early proliferation until typically 21 days later, well after the cells have differentiated to osteoblasts. Long-term perfusion of cells in the dynamic culture conditions was shown to be compatible with experimental optical demands and off-line optical analysis. We show that Raman optical analysis of cells and cellular differentiation in microbioreactors is feasible down to the level of subcellular organelles during development. We conclude that microbiore! actors combined with Raman microspectroscopy are a valuable tool to study hBMSC proliferation, differentiation, and development into tissues under in situ and in vitro conditions. PMID: 20143855 [PubMed - as supplied by publisher] | | | | 
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