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| Angiogenesis in a microvascular construct for transplantation depends on the method of chamber circulation.
June 3, 2010 at 7:51 AM
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| | Angiogenesis in a microvascular construct for transplantation depends on the method of chamber circulation. Tissue Eng Part A. 2010 Mar;16(3):795-805 Authors: Chang CC, Nunes SS, Sibole SC, Krishnan L, Williams SK, Weiss JA, Hoying JB Effective tissue prevascularization depends on new vessel growth and subsequent progression of neovessels into a stable microcirculation. Isolated microvessel fragments in a collagen-based microvascular construct (MVC) spontaneously undergo angiogenesis in static conditions in vitro but form a new microcirculation only when implanted in vivo. We have designed a bioreactor, the dynamic in vitro perfusion (DIP) chamber, to culture MVCs in vitro with perfusion. By altering bioreactor circulation, microvessel fragments in the DIP chamber either maintained stable, nonsprouting, patent vessel morphologies or sprouted endothelial neovessels that extended out into the surrounding collagen matrix (i.e., angiogenesis), yielding networks of neovessels within the MVC. Neovessels formed in regions of the construct predicted by simulation models to have the steepest gradients in oxygen levels and expressed hypoxia inducible factor-1alpha. By altering circulation conditions in t! he DIP chamber, we can control, possibly by modulating hypoxic stress, prevascularizing activity in vitro. PMID: 19778185 [PubMed - indexed for MEDLINE] | | |
| Fibroblast response to interstitial flow: a state-of-the-art review.
June 3, 2010 at 7:51 AM
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| | Fibroblast response to interstitial flow: a state-of-the-art review. Biotechnol Bioeng. 2010 Jun 1; Authors: Liu D, Chua CK, Leong KF Interstitial flow (IF) modulates both the biochemical and biophysical cues surrounding cells. It represents a very important regulating mechanism for cell/tissue function and has been commonly utilized in tissue engineering. This paper discusses the possible regulating mechanisms of IF on fibroblasts, the various fibroblast responses to IF, the current challenges in understanding the IF-fibroblast relationship and the application of IF for fibroblast involved tissue engineering. In particular, IF can affect fibroblast growth at both intracellular (e.g., calcium signaling, protein/proteinese secretion) and cellular (e.g., autocrine/paracrine signaling, proliferation, differentiation, alignment, adhesion, migration) levels. One major challenge for understanding IF-fibroblast interaction has been the determination of the flow and cell growth condition at micro-level especially in a three dimensional environment. To utilize IF and optimize the fluidic environment for ! tissue engineering, several influencing factors in the system including perfusate composition, flow profile, nutrient supply, signaling molecule effect, scaffold property and fibroblast type should be considered. . (c) 2010 Wiley Periodicals, Inc. PMID: 20517985 [PubMed - as supplied by publisher] | | |
| Macrophages in Alzheimer's disease: the blood-borne identity.
June 3, 2010 at 7:51 AM
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| | Macrophages in Alzheimer's disease: the blood-borne identity. J Neural Transm. 2010 Jun 2; Authors: Gate D, Rezai-Zadeh K, Jodry D, Rentsendorj A, Town T Alzheimer's disease (AD) is a progressive and incurable neurodegenerative disorder clinically characterized by cognitive decline involving loss of memory, reasoning and linguistic ability. The amyloid cascade hypothesis holds that mismetabolism and aggregation of neurotoxic amyloid-beta (Abeta) peptides, which are deposited as amyloid plaques, are the central etiological events in AD. Recent evidence from AD mouse models suggests that blood-borne mononuclear phagocytes are capable of infiltrating the brain and restricting beta-amyloid plaques, thereby limiting disease progression. These observations raise at least three key questions: (1) what is the cell of origin for macrophages in the AD brain, (2) do blood-borne macrophages impact the pathophysiology of AD and (3) could these enigmatic cells be therapeutically targeted to curb cerebral amyloidosis and thereby slow disease progression? This review begins with a historical perspective of peripheral mononuclear p! hagocytes in AD, and moves on to critically consider the controversy surrounding their identity as distinct from brain-resident microglia and their potential impact on AD pathology. PMID: 20517700 [PubMed - as supplied by publisher] | | |
| Tissue engineering scaffold material of porous nanohydroxyapatite/polyamide 66.
June 3, 2010 at 7:51 AM
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| | Tissue engineering scaffold material of porous nanohydroxyapatite/polyamide 66. Int J Nanomedicine. 2010;5:331-5 Authors: Xu Q, Lu H, Zhang J, Lu G, Deng Z, Mo A The aim of the study was to investigate a porous nanohydroxyapatite/polyamide 66 (n-HA/PA66) scaffold material that was implanted into muscle and tibiae of 16 New Zealand white rabbits to evaluate the biocompatibility and osteogenesis and osteoinductivity of the materials in vivo. The samples were harvested at 2, 4, 12 and 26 weeks respectively, and subjected to histological analysis. At 2 weeks, the experiment showed that osteogenesis was detected in porous n-HA/PA66 composite and the density of new bone formation was similar to the surrounding host bone at 12 weeks. The study indicated that three-dimensional pore structures could facilitate cell adhesion, differentiation and proliferation, and help with fibrovascular and nerve colonization. In conclusion, porous n-HA/PA66 scaffold material could be a good candidate as a bone substitute material used in clinics due to its excellent histocompatibility, osteoconductivity and osteoinductivity. PMID: 20517477 [PubMed - in process] | | |
| Decreased lung carcinoma cell density on select polymer nanometer surface features for lung replacement therapies.
June 3, 2010 at 7:51 AM
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| | Decreased lung carcinoma cell density on select polymer nanometer surface features for lung replacement therapies. Int J Nanomedicine. 2010;5:269-75 Authors: Zhang L, Chun YW, Webster TJ Poly(lactic-co-glycolic) acid (PLGA) has been widely used as a biomaterial in regenerative medicine because of its biocompatibility and biodegradability properties. Previous studies have shown that cells (such as bladder smooth muscle cells, chondrocytes, and osteoblasts) respond differently to nanostructured PLGA surfaces compared with nanosmooth surfaces. The purpose of the present in vitro research was to prepare PLGA films with various nanometer surface features and determine whether lung cancer epithelial cells respond differently to such topographies. To create nanosurface features on PLGA, different sized (190 nm, 300 nm, 400 nm, and 530 nm diameter) polystyrene beads were used to cast polydimethylsiloxane (PDMS) molds which were used as templates to create nanofeatured PLGA films. Atomic force microscopy (AFM) images and root mean square roughness (RMS) values indicated that the intended spherical surface nanotopographies on PLGA with RMS values of 2.23, 5! .03, 5.42, and 36.90 nm were formed by employing 190, 300, 400, and 530 nm beads. A solution evaporation method was also utilized to modify PLGA surface features by using 8 wt% (to obtain an AFM RMS value of 0.62 nm) and 4 wt% (to obtain an AFM RMS value of 2.23 nm) PLGA in chloroform solutions. Most importantly, lung cancer epithelial cells adhered less on the PLGA surfaces with RMS values of 0.62, 2.23, and 5.42 nm after four hours of culture compared with any other PLGA surface created here. After three days, PLGA surfaces with an RMS value of 0.62 nm had much lower cell density than any other sample. In this manner, PLGA with specific nanometer surface features may inhibit lung cancer cell density which may provide an important biomaterial for the treatment of lung cancer (from drug delivery to regenerative medicine). PMID: 20517474 [PubMed - in process] | | |
| Exploiting pluripotency for therapeutic gain.
June 3, 2010 at 7:51 AM
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| | Exploiting pluripotency for therapeutic gain. Panminerva Med. 2010 Jun;52(2):167-73 Authors: Deng W Human embryonic stem cells (hESCs) have been recognized as the "gold standard" for research on pluripotency and differentiation, and hold great promise for advancing our knowledge of human development, biology, disease and therapy. However, traditional techniques for generating hESCs rely on surplus IVF embryos and are incompatible with the generation of genetically diverse, patient- or disease-specific stem cells. A recent breakthrough in stem cell biology is the success of converting human somatic cells into pluripotent cells by using defined "reprogramming factors". While these reprogrammed cells have similar developmental potential as authentic hESCs, they are not derived from human embryos, and are thus termed "induced pluripotent stem cells (iPSCs)". The iPSC technology would prove useful for generation of individual cell lines from many different patients to study the nature and complexity of disease. Moreover, problems of immune rejection for future therap! eutic applications would be greatly relieved by being able to generate reprogrammed cells from individual patients. Although iPSC generation is still slow, inefficient, fraught with pitfalls, and unsafe for human use, recent research has yielded exciting insights into the understanding of the technology, logic, safety, and utility of iPSCs, and has led to the use of these unusual cells for disease modeling, drug discovery and regenerative medicine, paving paths to new therapeutics. PMID: 20517198 [PubMed - in process] | | |
| Neural stem cells in regenerative medicine: bridging the gap.
June 3, 2010 at 7:51 AM
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| | Neural stem cells in regenerative medicine: bridging the gap. Panminerva Med. 2010 Jun;52(2):125-47 Authors: Ruff CA, Fehlings MG Repair of the chronically injured spinal presents with multiple challenges, including neuronal/axonal loss and demyelination as a result of Primary Injury (usually a physical insult), as well as Secondary Damage, which includes ischemia, inflammation, oxidative injury and glutamatergic toxicity. These processes cause neuronal loss, axonal disruption and lead to a cystic degeneration and an inhibitory astroglial scar. A promising therapeutic intervention for SCI is the use of neural stem cells. Cell replacement strategies using neural precursor cells (NPCs) and oligodendroglial precursor cells (OPCs) have been shown to replace lost/damaged cells, secrete trophic factors, regulate gliosis and scar formation, reduce cystic cavity size and axonal dieback, as well as to enhance plasticity, axonal elongation and neuroprotection. These progenitor cells can be obtained through a variety of sources, including adult neural tissue, embryonic blastocysts and adult somatic cel! ls via induced pluripotent stem cell (iPSC) technology. The use of stem cell technology - especially autologous cell transplantation strategies - in regenerative therapy for SCI holds much promise; these therapies show high potential for clinical translation and for future disease treatment. PMID: 20517196 [PubMed - in process] | | |
| Creation of a vascularized composite graft with acellular dermal matrix and hydroxyapatite.
June 3, 2010 at 7:51 AM
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| | Creation of a vascularized composite graft with acellular dermal matrix and hydroxyapatite. Plast Reconstr Surg. 2010 Jun;125(6):1661-9 Authors: Woo AS, Jang JL, Liberman RF, Weinzweig J BACKGROUND:: Biomaterials have shown promise as potential substitutes for human tissue. Studies have demonstrated that attachment of a vascularized pedicle to dermal matrix grafts yields tissues that are resilient enough to patch hernia defects in rats. The purpose of this study was to examine the possibility of creating a viable composite graft completely from biomaterials. METHODS:: Acellular dermal matrix was enveloped around a square wafer of hydroxyapatite bone substitute. This composite graft was inserted into an extraperitoneal pocket overlying the abdominal musculature. In 30 Sprague-Dawley rats, the superficial epigastric arteriovenous pedicle was dissected free and placed within the midportion of the matrix construct on one side of each animal. A second graft was inserted on the opposite side without the addition of a vascularized pedicle. Each animal served as its own control. Animals were divided into three equal groups and euthanized at time points of! 30, 60, and 90 days. RESULTS:: Histologic evaluation of specimens was performed using hematoxylin and eosin and trichrome stains. At 30 days, the dermal matrices demonstrated full-thickness cellular infiltration in all specimens. Collagen deposition was significantly greater in the experimental group at every time point. Cellularity was significantly greater in the experimental group at 30 days, but there were no significant differences between groups at 60 or 90 days. CONCLUSIONS:: These results suggest that provision of an arteriovenous blood supply to nonbiologic tissue grafts significantly increases collagen deposition and early cellular deposition. Based on these findings, biomaterials may offer an exciting new method for tissue engineering. PMID: 20517089 [PubMed - in process] | | |
| Anti-VEGF effects of intravitreal erythropoietin in early diabetic retinopathy.
June 3, 2010 at 7:51 AM
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| | Anti-VEGF effects of intravitreal erythropoietin in early diabetic retinopathy. Front Biosci (Elite Ed). 2010;2:912-27 Authors: Zhang J, Hu LM, Xu G, Wu Y, Shen J, Luo Y, Zhong Y, Sinclair SH, Yanoff M, Li W, Xu GT In the present study, a single intravitreal erythropoietin (EPO) to diabetic rats produced therapeutic effects on blood-retinal barrier (BRB) function and neuronal survival at different time courses of retinopathy. In parallel, the hypoxia-inducible factor 1 alpha (HIF-1 alpha) pathway has been quantitatively studied, including VEGF-A, endogenous EPO, EPO receptor (EpoR), prolyl hydroxylases (PHD1-3) and von Hippel-Lindau tumor suppressor (VHL). The mRNA levels of HIF-1 alpha, VEGF-A, endogenous EPO, PHD1-3 and VHL are all up-regulated in the diabetic retina, and suppressed by exogenous EPO. The increased protein levels of HIF-1 alpha, VEGF-A, and endogenous EPO found in diabetic retinas also have been down-regulated by exogenous EPO. The results demonstrate that the HIF-1 pathway is activated in the retina in early diabetes, but is negatively regulated by a feedback loop following the administration of exogenous EPO. Exogenous EPO at pharmacologic levels leads to! suppression of VEGF and in turn, restoration of the normal functions of BRB in a time-dependent manner. In the diabetic retina, the same level of exogenous EPO that inhibits VEGF also exerted neuronal protection. PMID: 20515763 [PubMed - in process] | | |
| Genetic modification of ex-vivo expanded stem cells for clinical application.
June 3, 2010 at 7:51 AM
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| | Genetic modification of ex-vivo expanded stem cells for clinical application. Front Biosci. 2010;15:854-71 Authors: Aggarwal R, Pompili VJ, Das H Stem cell therapy is currently considered as an important regime for repairing, replacing or enhancing the biological functions of the damaged tissues. Among adult stem cells, hematopoietic stem cells (HSCs) are commonly used for cure of hematological disorders. However, the number of HSCs obtained from sources like bone marrow, peripheral or umbilical cord blood is not sufficient for routine clinical application. Thus, ex-vivo expansion of HSCs becomes critically important. Ex-vivo culture and expansion of stem cells are challenging, as stem cells differentiate in culture rather than self-renew. Lack of clarity about the factors responsible for quiescence and differentiation of HSCs, investigators struggled to optimize conditions for ex vivo expansion. As we understand better, various strategies can be incorporated to mimic in vivo conditions for successful expansion of stem cells. However, characterization and biological functionality should also be tested for e! xpanded stem cells prior to clinical application. To treat ischemia by enhancing therapeutic angiogenesis and neo-vascularization, the role of genetic modification of HSCs with pro-angiogenic factors is the focus of this review. PMID: 20515730 [PubMed - in process] | | |
| Jagged-Notch signaling ensures dorsal skeletal identity in the vertebrate face.
June 3, 2010 at 7:51 AM
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| | Jagged-Notch signaling ensures dorsal skeletal identity in the vertebrate face. Development. 2010 Jun;137(11):1843-52 Authors: Zuniga E, Stellabotte F, Crump JG The development of the vertebrate face relies on the regionalization of neural crest-derived skeletal precursors along the dorsoventral (DV) axis. Here we show that Jagged-Notch signaling ensures dorsal identity within the hyoid and mandibular components of the facial skeleton by repressing ventral fates. In a genetic screen in zebrafish, we identified a loss-of-function mutation in jagged 1b (jag1b) that results in dorsal expansion of ventral gene expression and partial transformation of the dorsal hyoid skeleton to a ventral morphology. Conversely, misexpression of human jagged 1 (JAG1) represses ventral gene expression and dorsalizes the ventral hyoid and mandibular skeletons. We further show that jag1b is expressed specifically in dorsal skeletal precursors, where it acts through the Notch2 receptor to activate hey1 expression. Whereas Jagged-Notch positive feedback propagates jag1b expression throughout the dorsal domain, Endothelin 1 (Edn1) inhibits jag1b an! d hey1 expression in the ventral domain. Strikingly, reduction of Jag1b or Notch2 function partially rescues the ventral defects of edn1 mutants, indicating that Edn1 promotes facial skeleton development in part by inhibiting Jagged-Notch signaling in ventral skeletal precursors. Together, these results indicate a novel function of Jagged-Notch signaling in ensuring dorsal identity within broad fields of facial skeletal precursors. PMID: 20431122 [PubMed - indexed for MEDLINE] | | |
| UTX mediates demethylation of H3K27me3 at muscle-specific genes during myogenesis.
June 3, 2010 at 7:51 AM
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| | UTX mediates demethylation of H3K27me3 at muscle-specific genes during myogenesis. EMBO J. 2010 Apr 21;29(8):1401-11 Authors: Seenundun S, Rampalli S, Liu QC, Aziz A, Palii C, Hong S, Blais A, Brand M, Ge K, Dilworth FJ Polycomb (PcG) and Trithorax (TrxG) group proteins act antagonistically to establish tissue-specific patterns of gene expression. The PcG protein Ezh2 facilitates repression by catalysing histone H3-Lys27 trimethylation (H3K27me3). For expression, H3K27me3 marks are removed and replaced by TrxG protein catalysed histone H3-Lys4 trimethylation (H3K4me3). Although H3K27 demethylases have been identified, the mechanism by which these enzymes are targeted to specific genomic regions to remove H3K27me3 marks has not been established. Here, we demonstrate a two-step mechanism for UTX-mediated demethylation at muscle-specific genes during myogenesis. Although the transactivator Six4 initially recruits UTX to the regulatory region of muscle genes, the resulting loss of H3K27me3 marks is limited to the region upstream of the transcriptional start site. Removal of the repressive H3K27me3 mark within the coding region then requires RNA Polymerase II (Pol II) elongation. Inte! restingly, blocking Pol II elongation on transcribed genes leads to increased H3K27me3 within the coding region, and formation of bivalent (H3K27me3/H3K4me3) chromatin domains. Thus, removal of repressive H3K27me3 marks by UTX occurs through targeted recruitment followed by spreading across the gene. PMID: 20300060 [PubMed - indexed for MEDLINE] | | |
| Curcumin prevents dopaminergic neuronal death through inhibition of the c-Jun N-terminal kinase pathway.
June 3, 2010 at 7:51 AM
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| | Curcumin prevents dopaminergic neuronal death through inhibition of the c-Jun N-terminal kinase pathway. Rejuvenation Res. 2010 Feb;13(1):55-64 Authors: Yu S, Zheng W, Xin N, Chi ZH, Wang NQ, Nie YX, Feng WY, Wang ZY Recent studies have shown that the c-Jun N-terminal kinase (JNK) signaling pathway is involved in dopaminergic neuronal degeneration, and direct blockade of JNK by specific inhibitors may prevent or effectively slow the progression of Parkinson disease (PD). Previous studies have revealed that the natural phenolic compound curcumin can reduce inflammation and oxidation, which makes it a potential therapeutic agent for neurodegenerative diseases. In this study, we investigated whether curcumin protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine- (MPTP) or 1-methyl-4-phenylpyridnium ion- (MPP(+)) induced dopaminergic neurotoxicity in C57BL/6N mice or SH-SY5Y cells by inhibiting JNK pathways both in vivo and in vitro. Curcumin treatment significantly improved behavioral deficits, and enhanced the survival of tyrosine hydroxylase-positive neurons in the substantia nigra (SN) in the MPTP-induced PD model mice. Most importantly, curcumin treatment significantl! y inhibited MPTP/MPP(+)-induced phosphorylation of JNK1/2 and c-Jun, and cleaved caspase-3. Our study suggests that the neuroprotective effect of curcumin is not related simply to its antiinflammatory and antioxidant properties, but involves other mechanisms, particularly by targeting the JNK pathways. PMID: 20230279 [PubMed - indexed for MEDLINE] | | |
| Stem cell-derived dopamine neurons for brain repair in Parkinson's disease.
June 3, 2010 at 7:51 AM
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| | Stem cell-derived dopamine neurons for brain repair in Parkinson's disease. Regen Med. 2010 Mar;5(2):267-78 Authors: Fricker-Gates RA, Gates MA One of the prospects for a curative treatment for Parkinson's disease is to replace the lost dopaminergic neurons. Preclinical and clinical trials have demonstrated that dissected fetal dopaminergic neurons have the potential to markedly improve motor function in animal models and Parkinson's disease patients. However, this source of cells will never be sufficient to use as a widespread therapy. Over the last 20 years, scientists have been searching for other reliable sources of midbrain dopamine neurons, and stem cells appear to be strong candidates. This article reviews the potential of different types of stem cells, from embryonic to adult to induced pluripotent stem cells, to see how well the cells can be differentiated into fully functional dopamine neurons, which cells might be the best candidates and how much more research is required before stem cell technology might be translated to a clinical therapy for Parkinson's disease. PMID: 20210586 [PubMed - indexed for MEDLINE] | | |
| Efficient isolation and chondrogenic differentiation of adult mesenchymal stem cells with fibrin microbeads and micronized collagen sponges.
June 3, 2010 at 7:51 AM
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| | Efficient isolation and chondrogenic differentiation of adult mesenchymal stem cells with fibrin microbeads and micronized collagen sponges. Regen Med. 2010 Mar;5(2):255-65 Authors: Shainer R, Gaberman E, Levdansky L, Gorodetsky R BACKGROUND: Mesenchymal stem cells (MSCs) have been demonstrated to potentially undergo chondrogenic differentiation. We propose a new matrix for stem cell-based chondrogenesis using dense fibrin microbeads (FMBs) combined with grounded dehydrothermally crosslinked collagen sponges (micronized collagen). METHODS: In this study, MSCs were isolated from bone marrow of transgenic green fluorescent protein C57/Bl mice by FMBs in high yield. After 48 h in slowly rotating suspension culture, micronized collagen was added. RESULTS: The cells on the FMBs migrated to the collagen pieces and formed aggregates that developed into cartilage-like structures. Following chondrogenic differentiation, alcian blue staining and collagen type II immunohistochemistry demonstrated the presence of chondrocytes in the 3D structures. PCR for the expression of aggrecan and collagen type II genes supported these findings. The in vitro structures that formed were used for ectopic subdermal i! mplantation in wild-type C57/Bl mice. However, the chondrogenic markers faded relative to the pre-implant in vitro structures. CONCLUSION: We propose that FMBs with micronized collagen could serve as a simple technology for MSC isolation and chondrogenesis as a basis for implantation. PMID: 20210585 [PubMed - indexed for MEDLINE] | | |
| Therapeutic angiogenesis by transplantation of human embryonic stem cell-derived CD133+ endothelial progenitor cells for cardiac repair.
June 3, 2010 at 7:51 AM
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| | Therapeutic angiogenesis by transplantation of human embryonic stem cell-derived CD133+ endothelial progenitor cells for cardiac repair. Regen Med. 2010 Mar;5(2):231-44 Authors: Rufaihah AJ, Haider HK, Heng BC, Ye L, Tan RS, Toh WS, Tian XF, Sim EK, Cao T OBJECTIVE: This study aim to enhance endothelial differentiation of human embryonic stem cells (hESCs) by transduction of an adenovirus (Ad) vector expressing hVEGF(165) gene (Ad-hVEGF(165) ). Purified hESC-derived CD133(+) endothelial progenitors were transplanted into a rat myocardial infarct model to assess their ability to contribute to heart regeneration. METHODS: Optimal transduction efficiency with high cell viability was achieved by exposing differentiating hESCs to viral particles at a ratio of 1:500 for 4 h on three consecutive days. RESULTS: Reverse transcription-PCR analysis showed positive upregulation of VEGF, Ang-1, Flt-1, Tie-2, CD34, CD31, CD133 and Flk-1 gene expression in Ad-hVEGF(165) -transduced cells. Additionally, flow cytometric analysis of CD133, a cell surface marker, revealed an approximately fivefold increase of CD133 marker expression in Ad-hVEGF(165)-transduced cells compared with the nontransduced control. Within a rat myocardial inf! arct model, transplanted CD133(+) endothelial progenitor cells survived and participated, both actively and passively, in the regeneration of the infarcted myocardium, as seen by an approximately threefold increase in mature blood vessel density (13.62 +/- 1.56 vs 5.11 +/- 1.23; p < 0.01), as well as significantly reduced infarct size (28% +/- 8.2% vs 76% +/- 5.6%; p < 0.01) in the transplanted group compared with the culture medium-injected control. There was significant improvement in heart function 6 weeks post-transplantation, as confirmed by regional blood-flow analysis (1.72 +/- 0.612 ml/min/g vs 0.8 +/- 0.256 ml/min/g; p < 0.05), as well as echocardiography assessment of left ventricular ejection fraction (60.855% +/- 7.7% vs 38.22 +/- 8.6%; p < 0.05) and fractional shortening (38.63% +/- 9.3% vs 25.2% +/- 7.11%; p < 0.05). CONCLUSION: hESC-derived CD133(+) endothelial progenitor cells can be utilized to regenerate the infarcted heart. PMID: 20210583 [PubMed - indexed for MEDLINE] | | |
| In vitro study of stem cell communication via gap junctions for fibrocartilage regeneration at entheses.
June 3, 2010 at 7:51 AM
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| | In vitro study of stem cell communication via gap junctions for fibrocartilage regeneration at entheses. Regen Med. 2010 Mar;5(2):221-9 Authors: Nayak BP, Goh JC, Toh SL, Satpathy GR BACKGROUND: Entheses are fibrocartilaginous organs that bridge ligament with bone at their interface and add significant insertional strength. To replace a severely damaged ligament, a tissue-engineered graft preinstalled with interfacial fibrocartilage, which is being regenerated from stem cells, appears to be more promising than ligament-alone graft. Such a concept can be realized by a biomimetic approach of establishing a dynamic communication of stem cells with bone cells and/or ligament fibroblasts in vitro. AIM: The current study has two objectives. The first objective is to demonstrate functional coculture of bone marrow-derived stem cells (BMSCs) with mature bone cells/ligament fibroblasts as evidenced by gap-junctional communication in vitro. The second objective is to investigate the role of BMSCs in the regeneration of fibrocartilage within the coculture. MATERIALS & METHODS: Rabbit bone/ligament fibroblasts were dual-stained with DiI-Red and calcei! n (gap-junction permeable dye), and cocultured with unlabeled BMSCs at fixed ratio (1:10). The functional gap junction was demonstrated by the transfer of calcein from donor to recipient cells that was confirmed and quantified by flow cytometry. Type 2 collagen (cartilage extracellular matrix-specific protein) expressed by the mixed cell lines in the cocultures were estimated by real-time reverse transcription PCR and compared with that of the ligament-bone coculture (control). RESULTS: Significant transfer of calcein into BMSCs was observed and flow cytometry analyses showed a gradual increase in the percentage of BMSCs acquiring calcein with time. Cocultures that included BMSCs expressed significantly more type 2 collagen compared with the control. CONCLUSION: The current study, for the first time, reported the expression of gap-junctional communication of BMSCs with two adherent cell lines of musculoskeletal system in vitro and also confirmed that incorporation of stem c! ells augments fibrocartilage regeneration. The results open up! a path to envisage a composite graft preinstalled with enthesial fibrocartilage using a stem cell-based coculture system. PMID: 20210582 [PubMed - indexed for MEDLINE] | | |
| The effects of DNA methyltransferase inhibitors and histone deacetylase inhibitors on digit regeneration in mice.
June 3, 2010 at 7:51 AM
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| | The effects of DNA methyltransferase inhibitors and histone deacetylase inhibitors on digit regeneration in mice. Regen Med. 2010 Mar;5(2):201-20 Authors: Wang G, Badylak SF, Heber-Katz E, Braunhut SJ, Gudas LJ METHOD: We injected two drugs that modify the epigenome, the DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) and the histone deacetylase inhibitor trichostatin A (TSA), alone or in combination, into C57Bl/6 mice subjected to amputation through the mid-second phalanx of the third digit. Wound-site tissue was collected. RESULTS: We observed increased staining of the stem cell markers Rex1 (Zfp42) and stem cell antigen-1 at digit amputation sites from drug-treated mice. Samples from 5-aza-dC plus TSA and TSA treated mice also showed increased proliferating cell nuclear antigen staining, a measure of cell proliferation. Drug treatments increased Msx1, but not Cyp26a1 or ALDH1a2 (RALDH2) mRNA. CONCLUSION: 5-aza-dC and TSA treatments stimulated cell proliferation at the amputation site, possibly via increased expression of genes involved in digit development and regeneration. PMID: 20210581 [PubMed - indexed for MEDLINE] | | |
| In remembrance: Michael J. Lysaght, 1942-2009.
June 3, 2010 at 7:51 AM
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| | In remembrance: Michael J. Lysaght, 1942-2009. Tissue Eng Part A. 2010 Mar;16(3):767-8 Authors: Leonard EF, Morgan JR, Nerem RM PMID: 20132048 [PubMed - indexed for MEDLINE] | | |
| Circulating endothelial progenitor cells: a new approach to anti-aging medicine?
June 3, 2010 at 7:51 AM
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| | Circulating endothelial progenitor cells: a new approach to anti-aging medicine? J Transl Med. 2009;7:106 Authors: Mikirova NA, Jackson JA, Hunninghake R, Kenyon J, Chan KW, Swindlehurst CA, Minev B, Patel AN, Murphy MP, Smith L, Alexandrescu DT, Ichim TE, Riordan NH Endothelial dysfunction is associated with major causes of morbidity and mortality, as well as numerous age-related conditions. The possibility of preserving or even rejuvenating endothelial function offers a potent means of preventing/treating some of the most fearful aspects of aging such as loss of mental, cardiovascular, and sexual function.Endothelial precursor cells (EPC) provide a continual source of replenishment for damaged or senescent blood vessels. In this review we discuss the biological relevance of circulating EPC in a variety of pathologies in order to build the case that these cells act as an endogenous mechanism of regeneration. Factors controlling EPC mobilization, migration, and function, as well as therapeutic interventions based on mobilization of EPC will be reviewed. We conclude by discussing several clinically-relevant approaches to EPC mobilization and provide preliminary data on a food supplement, Stem-Kine, which enhanced EPC mobilizati! on in human subjects. PMID: 20003528 [PubMed - indexed for MEDLINE] | | |
| Implantation of capillary structure engineered by optical lithography improves hind limb ischemia in mice.
June 3, 2010 at 7:51 AM
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| | Implantation of capillary structure engineered by optical lithography improves hind limb ischemia in mice. Tissue Eng Part A. 2010 Mar;16(3):953-9 Authors: Akahori T, Kobayashi A, Komaki M, Hattori H, Nakahama K, Ichinose S, Abe M, Takeda S, Morita I We previously reported a novel optical lithographic technique for the construction of a capillary network consisting of endothelial cells. To investigate the feasibility of clinical application in the treatment of ischemic diseases, capillary structures were formed on scaffolds made from amniotic membrane (AM) and implanted into mice. The capillary network remained in place for at least 5 days and blood perfusion through the implanted capillaries was histologically detected in an ear flap model. Moreover, blood was observed flowing through the capillary network implanted in abdominal subcutaneous tissue of mice at 5 days after insertion. Implantation of the AM capillary structure into the ischemic hind limbs of mice significantly increased reperfusion compared with controls (AM only). Blood flow was restored in the ischemic limbs to the level of corresponding nonischemic limbs as early as 9 days after surgical implantation. The treatment reversed ischemic symptoms! , and ambulatory impairment was significantly improved. Thus, the implantation of a capillary network engineered ex vivo could have therapeutic potential for ischemic diseases. PMID: 19947885 [PubMed - indexed for MEDLINE] | | |
| The development and characterization of an organotypic tissue-engineered human esophageal mucosal model.
June 3, 2010 at 7:51 AM
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| | The development and characterization of an organotypic tissue-engineered human esophageal mucosal model. Tissue Eng Part A. 2010 Mar;16(3):1053-64 Authors: Green N, Huang Q, Khan L, Battaglia G, Corfe B, MacNeil S, Bury JP There is a demand for a reliable three-dimensional tissue-engineered model of the esophageal mucosa for use as an experimental platform for investigating esophageal epithelial biology and the pathogenesis of esophageal neoplasia and precursor lesions such as Barrett's metaplasia. A number of models have been described, but there has been little systematic assessment of the different approaches, making selection of a preferred platform difficult. This study assesses the properties of organotypic cultures using four different scaffolds (human esophageal matrix, porcine esophageal matrix, human dermal matrix, and collagen) and two different epithelial cell types (primary human esophageal squamous cells and the Het-1A esophageal squamous cell line). Human esophageal matrix and dermis did not give consistent results, but porcine esophageal matrix and collagen proved more reliable and were studied in greater detail. Both matrices supported the formation of a mature stra! tified epithelium that was similar to that of the normal human esophagus, demonstrated by Ki67, CK4, CK14, and involucrin staining. However, collagen showed reduced epithelial adherence, while fibroblast penetration into the porcine matrix was poor. Composite cultures using Het-1A cells formed a hyperproliferative epithelium with no evidence of differentiation. We propose human esophageal squamous cells seeded onto porcine esophageal matrix as the preferred model of the normal human esophagus. PMID: 19845463 [PubMed - indexed for MEDLINE] | | |
| Uniaxial strain regulates morphogenesis, gene expression, and tissue strength in engineered skin.
June 3, 2010 at 7:51 AM
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| | Uniaxial strain regulates morphogenesis, gene expression, and tissue strength in engineered skin. Tissue Eng Part A. 2010 Mar;16(3):1083-92 Authors: Powell HM, McFarland KL, Butler DL, Supp DM, Boyce ST Mechanical properties of engineered tissues should ideally match those of the tissues that are replaced. Engineered skin (ES) is often orders of magnitude weaker than normal skin, which can lead to damage during application and improper function after engraftment. Hypothetically, application of strain during culture of ES may lead to improved mechanical properties. ES comprised of electrospun collagen scaffolds, human dermal fibroblasts, and epidermal keratinocytes were fabricated and cultured at the air-liquid interface. ES was loaded in vitro into a strain apparatus, strained to 0% (restrained), 5%, 10%, 20%, or 40%, with unstrained ES as a control, and cultured for 10 days. ES cultured under 10% and 20% strain were significantly stronger than unstrained controls. ES cultured under 20% strain showed upregulation of many genes encoding structural extracellular matrix proteins, including collagen type I alpha 1 and fibronectin 1. Mechanical stimulation significant! ly increased epidermal cell proliferation and enhanced epidermal differentiation with 5%, 10%, and 20% strain. Improved strength in the 10% and 20% strain groups is likely a result of increased extracellular matrix production coupled with enhanced epidermal differentiation. These improvements to ES may facilitate surgical application, prevent damage during transplantation, and may result in improved functional outcomes after engraftment. PMID: 19845460 [PubMed - indexed for MEDLINE] | | |
| Localization of the potential zonal marker clusterin in native cartilage and in tissue-engineered constructs.
June 3, 2010 at 7:51 AM
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| | Localization of the potential zonal marker clusterin in native cartilage and in tissue-engineered constructs. Tissue Eng Part A. 2010 Mar;16(3):897-904 Authors: Malda J, ten Hoope W, Schuurman W, van Osch GJ, van Weeren PR, Dhert WJ An increasing number of studies aim to engineer cartilage tissue that more closely mimic the zonal organization of native articular tissue. Further understanding of zonal differences is crucial for successful development and evaluation of such grafts. We therefore aimed to characterize the secretion of the potential zonal marker clusterin by zonal articular chondrocytes in osteoarthritic and healthy articular cartilage and in tissue-engineered constructs. Clusterin secreted by superficial, middle, and deep zones equine chondrocytes was immunolocalized in cytospins of alginate cultured superficial, middle, and deep zones equine chondrocytes. Clusterin was present within the superficial zone of native cartilage; after isolation of the cells from healthy articular cartilage, staining for clusterin was limited to cells derived from the superficial zone. Staining disappeared after expansion, but reappeared during (re)differentiation and was more pronounced within the c! ultures derived from the superficial zones of the cartilage. The presence of clusterin was associated with clusters of differentiating chondrocytes, rather than highly proliferative cells and did not specifically colocalize with proteoglycan-4. Because staining for clusterin was more abundant in cultures of superficial chondrocytes compared to those of cells of the deeper layers, it may be used to further characterize zonal cartilage constructs. PMID: 19814590 [PubMed - indexed for MEDLINE] | | |
| Scleral reinforcement through host tissue integration with biomimetic enzymatically degradable semi-interpenetrating polymer network.
June 3, 2010 at 7:51 AM
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| | Scleral reinforcement through host tissue integration with biomimetic enzymatically degradable semi-interpenetrating polymer network. Tissue Eng Part A. 2010 Mar;16(3):905-16 Authors: Su J, Wall ST, Healy KE, Wildsoet CF Enzymatically degradable semi-interpenetrating polymer networks (edsIPNs) were explored for their biocompatibility and ability to promote new scleral tissue growth, as a means of reinforcing the posterior wall of the eye. The edsIPNs comprised thermoresponsive poly(N-isopropylacrylamide-co-acrylic acid), customizable peptide crosslinkers cleavable by matrix metalloproteinases, and interpenetrating linear poly(acrylic acid)-graft-peptide chains to engage with cell surface receptors. Rheological studies revealed an increase in stiffness at body temperature; the complex shear modulus |G*| was 14.13 +/- 6.13 Pa at 22 degrees C and 63.18 +/- 12.24 Pa at 37 degrees C, compatible with injection at room temperature. Primary chick scleral fibroblasts and chondrocytes cultured on edsIPN increased by 15.1- and 11.1-fold, respectively, over 11 days; both exhibited delayed onset of exponential growth compared with the cells plated on tissue culture polystyrene. The edsIPN was ! delivered by retrobulbar injection (100 microL) to nine 2-week-old chicks to assess biocompatibility in vivo. Ocular axial dimensions were assessed using A-scan ultrasonography over 28 days, after which eyes were processed for histological analysis. Although edsIPN injections did not affect the rate of ocular elongation, the outer fibrous sclera showed significant thickening. The demonstration that injectable biomimetic edsIPNs stimulate scleral fibrous tissue growth represents proof-of-principle for a novel approach for scleral reinforcement and a potential therapy for high myopia. PMID: 19814587 [PubMed - indexed for MEDLINE] | | | | 
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