| Gene therapy in transplantation: Toward clinical trials.
October 7, 2009 at 8:36 am
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| | Gene therapy in transplantation: Toward clinical trials. Curr Opin Mol Ther. 2009 Oct;11(5):504-12 Authors: Ritter T, Nosov M, Griffin MD The genetic modification of organs or cells is an attractive approach to protect allogeneic transplants from acute rejection and other complications. The transplant setting offers a unique opportunity to utilize ex vivo gene therapy for the modification of allogeneic organs and tissues prior to implantation. However, significant challenges exist in the application of this concept to human organ transplantation, including the large number of potential molecular targets, the diversity and safety profile of available vector delivery systems and the merging of gene-based therapies with existing immunosuppressive regimens. Accordingly, many different therapeutic concepts and vector systems have been investigated in preclinical studies with the aim of prolonging allograft survival. However, the translation of promising gene therapy strategies to transplant clinical trials has lagged behind the progress made in other medical fields. This review describes the recent preclinical applications of gene transfer to transplantation, and critically evaluates the degree to which gene therapy has been tested clinically in organ transplant recipients. PMID: 19806498 [PubMed - in process] |
| Activin/Nodal inhibition alone accelerates highly efficient neural conversion from human embryonic stem cells and imposes a caudal positional identity.
October 7, 2009 at 8:36 am
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| | Activin/Nodal inhibition alone accelerates highly efficient neural conversion from human embryonic stem cells and imposes a caudal positional identity. PLoS One. 2009;4(10):e7327 Authors: Patani R, Compston A, Puddifoot CA, Wyllie DJ, Hardingham GE, Allen ND, Chandran S BACKGROUND: Neural conversion from human embryonic stem cells (hESCs) has been demonstrated in a variety of systems including chemically defined suspension culture, not requiring extrinsic signals, as well as in an adherent culture method that involves dual SMAD inhibition using Noggin and SB431542 (an inhibitor of activin/nodal signaling). Previous studies have also determined a role for activin/nodal signaling in development of the neural plate and anterior fate specification. We therefore sought to investigate the independent influence of SB431542 both on neural commitment of hESCs and positional identity of derived neural progenitors in chemically defined substrate-free conditions. METHODOLOGY/PRINCIPAL FINDINGS: We show that in non-adherent culture conditions, treatment with SB431542 alone for 8 days is sufficient for highly efficient and accelerated neural conversion from hESCs with negligible mesendodermal, epidermal or trophectodermal contamination. In addition the resulting neural progenitor population has a predominantly caudal identity compared to the more anterior positional fate of non-SB431542 treated cultures. Finally we demonstrate that resulting neurons are electro-physiologically competent. CONCLUSIONS: This study provides a platform for the efficient generation of caudal neural progenitors under defined conditions for experimental study. PMID: 19806200 [PubMed - in process] |
| Transcription factor Glis3: a novel critical player in the regulation of pancreatic {beta}-cell development and insulin gene expression.
October 7, 2009 at 8:36 am
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| | Transcription factor Glis3: a novel critical player in the regulation of pancreatic {beta}-cell development and insulin gene expression. Mol Cell Biol. 2009 Oct 5; Authors: Kang HS, Kim YS, Zeruth G, Beak JY, Gerrish K, Kilic G, Sosa-Pineda B, Jensen J, Foley J, Jetten AM In this study, we report that the Krüppel-like zinc finger transcription factor Gli-similar 3 (Glis3) is induced during the secondary transition of pancreatic development, a stage of cell lineage specification and extensive patterning, and that Glis3(zf/zf) mutant mice develop neonatal diabetes, evidenced by hyperglycemia and hypoinsulinemia. The Glis3(zf/zf) pancreas shows a dramatic loss of beta and delta cells contrasting a smaller relative loss of alpha, PP, and epsilon cells. In addition, Glis3(zf/zf) mice develop ductal cysts, while no significant changes were observed in acini. Gene expression profiling and immunofluorescent staining demonstrated that the expression of pancreatic hormones and several transcription factors important in endocrine development, including Ngn3, MafA, and Pdx1, were significantly decreased in the developing pancreas of Glis3(zf/zf) mice. The population of pancreatic progenitors appears not to be greatly affected in Glis3(zf/zf) mice; however, the number of neurogenin 3 (Ngn3) positive, endocrine progenitors is significantly reduced. Our study indicates that Glis3 plays a key role in cell lineage specification, particularly in the development of mature pancreatic beta-cells. In addition, we provide evidence that Glis3 regulates insulin gene expression through two Glis-binding sites in its proximal promoter indicating that Glis3 also regulates beta-cell function. PMID: 19805515 [PubMed - as supplied by publisher] |
| Physiological function and transplantation of scaffold-free and vascularized human cardiac muscle tissue.
October 7, 2009 at 8:36 am
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| | Physiological function and transplantation of scaffold-free and vascularized human cardiac muscle tissue. Proc Natl Acad Sci U S A. 2009 Sep 29;106(39):16568-73 Authors: Stevens KR, Kreutziger KL, Dupras SK, Korte FS, Regnier M, Muskheli V, Nourse MB, Bendixen K, Reinecke H, Murry CE Success of human myocardial tissue engineering for cardiac repair has been limited by adverse effects of scaffold materials, necrosis at the tissue core, and poor survival after transplantation due to ischemic injury. Here, we report the development of scaffold-free prevascularized human heart tissue that survives in vivo transplantation and integrates with the host coronary circulation. Human embryonic stem cells (hESCs) were differentiated to cardiomyocytes by using activin A and BMP-4 and then placed into suspension on a rotating orbital shaker to create human cardiac tissue patches. Optimization of patch culture medium significantly increased cardiomyocyte viability in patch centers. These patches, composed only of enriched cardiomyocytes, did not survive to form significant grafts after implantation in vivo. To test the hypothesis that ischemic injury after transplantation would be attenuated by accelerated angiogenesis, we created "second-generation," prevascularized, and entirely human patches from cardiomyocytes, endothelial cells (both human umbilical vein and hESC-derived endothelial cells), and fibroblasts. Functionally, vascularized patches actively contracted, could be electrically paced, and exhibited passive mechanics more similar to myocardium than patches comprising only cardiomyocytes. Implantation of these patches resulted in 10-fold larger cell grafts compared with patches composed only of cardiomyocytes. Moreover, the preformed human microvessels anastomosed with the rat host coronary circulation and delivered blood to the grafts. Thus, inclusion of vascular and stromal elements enhanced the in vitro performance of engineered human myocardium and markedly improved viability after transplantation. These studies demonstrate the importance of including vascular and stromal elements when designing human tissues for regenerative therapies. PMID: 19805339 [PubMed - in process] |
| Feeder-free derivation of induced pluripotent stem cells from adult human adipose stem cells.
October 7, 2009 at 8:36 am
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| | Feeder-free derivation of induced pluripotent stem cells from adult human adipose stem cells. Proc Natl Acad Sci U S A. 2009 Sep 15;106(37):15720-5 Authors: Sun N, Panetta NJ, Gupta DM, Wilson KD, Lee A, Jia F, Hu S, Cherry AM, Robbins RC, Longaker MT, Wu JC Ectopic expression of transcription factors can reprogram somatic cells to a pluripotent state. However, most of the studies used skin fibroblasts as the starting population for reprogramming, which usually take weeks for expansion from a single biopsy. We show here that induced pluripotent stem (iPS) cells can be generated from adult human adipose stem cells (hASCs) freshly isolated from patients. Furthermore, iPS cells can be readily derived from adult hASCs in a feeder-free condition, thereby eliminating potential variability caused by using feeder cells. hASCs can be safely and readily isolated from adult humans in large quantities without extended time for expansion, are easy to maintain in culture, and therefore represent an ideal autologous source of cells for generating individual-specific iPS cells. PMID: 19805220 [PubMed - in process] |
| The role of fluctuations and stress on the effective viscosity of cell aggregates.
October 7, 2009 at 8:36 am
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| | The role of fluctuations and stress on the effective viscosity of cell aggregates. Proc Natl Acad Sci U S A. 2009 Sep 25; Authors: Marmottant P, Mgharbel A, Käfer J, Audren B, Rieu JP, Vial JC, van der Sanden B, Marée AF, Graner F, Delanoë-Ayari H Cell aggregates are a tool for in vitro studies of morphogenesis, cancer invasion, and tissue engineering. They respond to mechanical forces as a complex rather than simple liquid. To change an aggregate's shape, cells have to overcome energy barriers. If cell shape fluctuations are active enough, the aggregate spontaneously relaxes stresses ("fluctuation-induced flow"). If not, changing the aggregate's shape requires a sufficiently large applied stress ("stress-induced flow"). To capture this distinction, we develop a mechanical model of aggregates based on their cellular structure. At stress lower than a characteristic stress tau*, the aggregate as a whole flows with an apparent viscosity eta*, and at higher stress it is a shear-thinning fluid. An increasing cell-cell tension results in a higher eta* (and thus a slower stress relaxation time t(c)). Our constitutive equation fits experiments of aggregate shape relaxation after compression or decompression in which irreversibility can be measured; we find t(c) of the order of 5 h for F9 cell lines. Predictions also match numerical simulations of cell geometry and fluctuations. We discuss the deviations from liquid behavior, the possible overestimation of surface tension in parallel-plate compression measurements, and the role of measurement duration. PMID: 19805170 [PubMed - as supplied by publisher] |
| Regenerative Medicine Special Feature: Genetic engineering of human stem cells for enhanced angiogenesis using biodegradable polymeric nanoparticles.
October 7, 2009 at 8:36 am
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| | Regenerative Medicine Special Feature: Genetic engineering of human stem cells for enhanced angiogenesis using biodegradable polymeric nanoparticles. Proc Natl Acad Sci U S A. 2009 Oct 5; Authors: Yang F, Cho SW, Son SM, Bogatyrev SR, Singh D, Green JJ, Mei Y, Park S, Bhang SH, Kim BS, Langer R, Anderson DG Stem cells hold great potential as cell-based therapies to promote vascularization and tissue regeneration. However, the use of stem cells alone to promote angiogenesis remains limited because of insufficient expression of angiogenic factors and low cell viability after transplantation. Here, we have developed vascular endothelial growth factor (VEGF) high-expressing, transiently modified stem cells for the purposes of promoting angiogenesis. Nonviral, biodegradable polymeric nanoparticles were developed to deliver hVEGF gene to human mesenchymal stem cells (hMSCs) and human embryonic stem cell-derived cells (hESdCs). Treated stem cells demonstrated markedly enhanced hVEGF production, cell viability, and engraftment into target tissues. S.c. implantation of scaffolds seeded with VEGF-expressing stem cells (hMSCs and hESdCs) led to 2- to 4-fold-higher vessel densities 2 weeks after implantation, compared with control cells or cells transfected with VEGF by using Lipofectamine 2000, a leading commercial reagent. Four weeks after intramuscular injection into mouse ischemic hindlimbs, genetically modified hMSCs substantially enhanced angiogenesis and limb salvage while reducing muscle degeneration and tissue fibrosis. These results indicate that stem cells engineered with biodegradable polymer nanoparticles may be therapeutic tools for vascularizing tissue constructs and treating ischemic disease. PMID: 19805054 [PubMed - as supplied by publisher] |
| Physical forces in myelination and repair: a question of balance?
October 7, 2009 at 8:36 am
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| | Physical forces in myelination and repair: a question of balance? J Biol. 2009 Sep 25;8(8):78 Authors: Bauer NG, Ffrench-Constant C ABSTRACT: A recent report in BMC Cell Biology examines how the balance of extracellular forces and intracellular contractions regulate the shape changes required for oligodendrocyte myelination. A failure of remyelination such as seen in multiple sclerosis could be caused by loss of this balance.See related research article http://www.biomedcentral.com/1471-2121/10/71. PMID: 19804608 [PubMed - as supplied by publisher] |
| The role of bone marrow-derived mesenchymal stem cells in treating formocresol induced oral ulcers in dogs.
October 7, 2009 at 8:36 am
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| | The role of bone marrow-derived mesenchymal stem cells in treating formocresol induced oral ulcers in dogs. J Oral Pathol Med. 2009 Oct 4; Authors: El-Menoufy H, Aly LA, Aziz MT, Atta HM, Roshdy NK, Rashed LA, Sabry D J Oral Pathol Med (2009)Background: Mesenchymal stem cells (MSCs), a subpopulation of adult somatic stem cells, are an attractive stem cell source in regenerative medicine because of their multipotentiality. In this study, the effects of MSCs transplantation on oral ulcer healing were examined. Methods: Mesenchymal stem cells were isolated from bone marrow aspirates of dogs by dish adherence and expanded in culture. Oral ulcers were induced by topical application of formocresol in the oral cavity of dogs. Either autologous MSCs or vehicle (saline) was injected around the ulcer. The healing process of the ulcer was monitored clinically and histopathologically. Gene expression of vascular endothelial growth factor (VEGF) was detected in MSCs by reverse transcription-polymerase chain reaction. Expression of VEGF and collagen genes was detected in biopsies from all ulcers. Results: Mesenchymal stem cells expressed mRNA for VEGF MSCs transplantation significantly accelerated oral ulcer healing compared with controls. There was increased expression of both collagen and VEGF genes in MSCs-treated ulcers compared with controls. Conclusion: Mesenchymal stem cells transplantation may help accelerate oral ulcer healing, possibly through the induction of angiogenesis by VEGF together with increased intracellular matrix formation as detected by increased collagen gene expression. PMID: 19804505 [PubMed - as supplied by publisher] |
| Cartilage Tissue Engineering: Towards a Biomaterial-assisted Mesenchymal Stem Cell Therapy.
October 7, 2009 at 8:36 am
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| | Cartilage Tissue Engineering: Towards a Biomaterial-assisted Mesenchymal Stem Cell Therapy. Curr Stem Cell Res Ther. 2009 Dec 1; Authors: Vinatier C, Bouffi C, Merceron C, Gordeladze J, Brondello JM, Jorgensen C, Weiss P, Guicheux J, Noël D Injuries to articular cartilage are one of the most challenging issues of musculoskeletal medicine due to the poor intrinsic ability of this tissue for repair. Despite progress in orthopaedic surgery, the lack of efficient modalities of treatment for large chondral defects has prompted research on tissue engineering combining chondrogenic cells, scaffold materials and environmental factors. The aim of this review is to focus on the recent advances made in exploiting the potentials of cell therapy for cartilage engineering. These include: 1) defining the best cell candidates between chondrocytes or multipotent progenitor cells, such as multipotent mesenchymal stromal cells (MSC), in terms of readily available sources for isolation, expansion and repair potential; 2) engineering biocompatible and biodegradable natural or artificial matrix scaffolds as cell carriers, chondrogenic factors releasing factories and supports for defect filling, 3) identifying more specific growth factors and the appropriate scheme of application that will promote both chondrogenic differentiation and then maintain the differentiated phenotype overtime and 4) evaluating the optimal combinations that will answer to the functional demand placed upon cartilage tissue replacement in animal models and in clinics. Finally, some of the major obstacles generally encountered in cartilage engineering are discussed as well as future trends to overcome these limiting issues for clinical applications. PMID: 19804369 [PubMed - as supplied by publisher] |
| Regenerative medicine with endometrial regenerative cells for critical ischemia: limb salvage from the cradle of life?
October 7, 2009 at 8:36 am
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| | Regenerative medicine with endometrial regenerative cells for critical ischemia: limb salvage from the cradle of life? Future Cardiol. 2008 Nov;4(6):547-50 Authors: Angle N PMID: 19804348 [PubMed - in process] |
| Mesenchymal stromal cell and mononuclear cell therapy in heart disease.
October 7, 2009 at 8:36 am
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| | Mesenchymal stromal cell and mononuclear cell therapy in heart disease. Future Cardiol. 2008 Sep;4(5):481-94 Authors: Haack-Sorensen M, Friis T, Kastrup J Despite progress in percutaneous coronary intervention, bypass surgery and drug therapy, rates of mortality and morbidity after acute coronary syndrome are high due to ventricular remodeling and heart failure. Mesenchymal stromal cells (MSCs) from adult bone marrow or adipose tissue are considered potential candidates for therapeutic regenerative treatment in cardiovascular disease. Recent animal studies have demonstrated that MSCs can induce neovascularization and improve myocardial function in postinfarction myocardial ischemic hearts. This review will focus on the present preclinical and clinical knowledge about the use of mononuclear cells and MSCs for cardiac regenerative medicine, the source of MSCs for clinical use and problems to consider when conducting clinical MSC therapy. PMID: 19804342 [PubMed - in process] |
| [Gene-stem Cell therapy for ischemic stroke]
October 7, 2009 at 8:36 am
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| | [Gene-stem Cell therapy for ischemic stroke] Brain Nerve. 2009 Sep;61(9):1043-9 Authors: Abe K Besides blood flow restoration, neuroprotection is essential for treating strokes at an acute stage. Both neurotrophic factors (NTFs) and free radical scavengers can act as neuroprotective agents with abilities to inhibit cell death and facilitate cell survival under cerebral ischemia. For example, topical application of glial cell line-derived neurotrophic factor (GDNF) remarkably reduced infarct size and brain edema after middle cerebral artery (MCA) occlusion in rats. Reduction in the infarct size was not found to be related to a change in the cerebral blood flow (CBF), but was accompanied by marked reduction in BrdU-positive cells in the affected area after TdT-mediated dUTP-biotin nick end labeling (TUNEL) for caspses. Thus, GDNF elicited a direct protective effect against ischemic brain damage, but without improving CBF. Sendai virus vectors harboring the GDNF gene led to a remarkable reduction in infract volume without affecting regional CBF but reduced the translocation of apoptosis inducible factor (AIF) from the mitochondria to cytoplasm. Regenerative therapy involving neural stem cells which are intrinsically activated or exogenously transplanted, is an important treatment strategy. To facilitate stem cell migration, an artificial scaffold can be implanted into the injured brain for promoting ischemic brain repair. Addition of NTFs greatly enhanced an intrinsic migration or invasion of stem cells into the scaffold: this strategy could be used in the future for enhancing regenerative potential of brain cells after chronic ischemia-induced brain damage. PMID: 19803403 [PubMed - in process] |
| [Tissue-engineering bone with ADSCs and coral scaffold for repairing of cranial bone defect in canine]
October 7, 2009 at 8:36 am
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| | [Tissue-engineering bone with ADSCs and coral scaffold for repairing of cranial bone defect in canine] Zhonghua Zheng Xing Wai Ke Za Zhi. 2009 May;25(3):204-8 Authors: Liu B, Cui L, Liu GP, Cao YL, Zhu JT, Cao Y OBJECTIVE: To investigate the application of tissue-engineering bone with ADSCs (adipose-derived stem cells) and coral scaffold for repairing of cranial bone defect in canine. METHODS: Autologous ADSCs isolated from canine subcutaneous fat were expanded, osteogenically induced, and seeded on coral scaffolds. Bilateral full-thickness defects (20 mm x 20 mm) of parietal bone were created (n = 7). The defects were either repaired with ADSC-coral constructs (experimental group) or with coral alone (control group). Radiological, gross, biomechanical and histological observations were done to evaluate the bone regeneration. RESULTS: Three-dimensional CT scan showed that new bones were formed in the experimental group at 12 weeks after implantation, while coral scaffolds were partially degraded in the control group. By radiographic analysis at 24 weeks post-transplantation, it showed that an average repair percentage of each defect was (84.19 +/- 6.45)% in experimental group, and (25.04 +/- 18.82)% in control group (P < 0.01). The maximum compression loading was (73.45 +/- 17.26) N in experimental group, and (104.27 +/- 22.71) N in control group (P <0.01). Histological examination revealed that the defect was repaired by typical bone tissue in experimental group, while only minimal bone formation with fibrous connection in the control group. CONCLUSIONS: The tissue-engineering bone with autologous osteogenic ADSCs and scaffold could successfully repair the cranial defects in canine models. PMID: 19803204 [PubMed - in process] |
| The interaction between bone marrow stromal cells and RGD-modified three-dimensional porous polycaprolactone scaffolds.
October 7, 2009 at 8:36 am
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| | The interaction between bone marrow stromal cells and RGD-modified three-dimensional porous polycaprolactone scaffolds. Biomaterials. 2009 Sep;30(25):4063-9 Authors: Zhang H, Lin CY, Hollister SJ We previously established a simple method to immobilize the Arg-Gly-Asp (RGD) peptide on polycaprolactone (PCL) two-dimensional film surfaces that significantly improved bone marrow stromal cell (BMSC) adhesion to these films. The current work extends this modification strategy to three-dimensional (3D) PCL scaffolds to investigate BMSC attachment, cellular distribution and cellularity, signal transduction and survival on the modified PCL scaffold compared to those on the untreated ones. The results demonstrated that treatment of 3D PCL scaffold surfaces with 1,6-hexanediamine introduced the amino functional groups onto the porous PCL scaffold homogenously as detected by a ninhydrin staining method. Followed by the cross-linking reaction, RGDC peptide was successfully immobilized on the surface of PCL scaffold. Although the static seeding method used in this study caused heterogeneous cell distribution, the RGD-modified PCL scaffold still demonstrated the improved BMSC attachment and cellular distribution in the scaffold. More importantly, the integrin-mediated signal transduction FAK-PI3K-Akt pathway was significantly up-regulated by RGD modification and a subsequent increase in cell survival and growth was found in the modified scaffold. The present study introduces an easy method to immobilize RGD peptide on the 3D porous PCL scaffold and provides further evidence that modification of 3D PCL scaffolds with RGD peptides elicits specific cellular responses and improves the final cell-biomaterial interaction. PMID: 19487019 [PubMed - indexed for MEDLINE] |
| Computational modelling of the mechanical environment of osteogenesis within a polylactic acid-calcium phosphate glass scaffold.
October 7, 2009 at 8:36 am
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| | Computational modelling of the mechanical environment of osteogenesis within a polylactic acid-calcium phosphate glass scaffold. Biomaterials. 2009 Sep;30(25):4219-26 Authors: Milan JL, Planell JA, Lacroix D A computational model based on finite element method (FEM) and computational fluid dynamics (CFD) is developed to analyse the mechanical stimuli in a composite scaffold made of polylactic acid (PLA) matrix with calcium phosphate glass (Glass) particles. Different bioreactor loading conditions were simulated within the scaffold. In vitro perfusion conditions were reproduced in the model. Dynamic compression was also reproduced in an uncoupled fluid-structure scheme: deformation level was studied analyzing the mechanical response of scaffold alone under static compression while strain rate was studied considering the fluid flow induced by compression through fixed scaffold. Results of the model show that during perfusion test an inlet velocity of 25 microm/s generates on scaffold surface a fluid flow shear stress which may stimulate osteogenesis. Dynamic compression of 5% applied on the PLA-Glass scaffold with a strain rate of 0.005 s(-1) has the benefit to generate mechanical stimuli based on both solid shear strain and fluid flow shear stress on large scaffold surface area. Values of perfusion inlet velocity or compression strain rate one order of magnitude lower may promote cell proliferation while values one order of magnitude higher may be detrimental for cells. FEM-CFD scaffold models may help to determine loading conditions promoting bone formation and to interpret experimental results from a mechanical point of view. PMID: 19477510 [PubMed - indexed for MEDLINE] |
| The use of vitrification to preserve primary rat hepatocyte monolayer on collagen-coated poly(ethylene-terephthalate) surfaces for a hybrid liver support system.
October 7, 2009 at 8:36 am
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| | The use of vitrification to preserve primary rat hepatocyte monolayer on collagen-coated poly(ethylene-terephthalate) surfaces for a hybrid liver support system. Biomaterials. 2009 Sep;30(25):4136-42 Authors: Magalhães R, Anil Kumar PR, Wen F, Zhao X, Yu H, Kuleshova LL We developed a scaled-up procedure for vitrifying hepatocytes for hybrid liver support system applications. Hepatocyte monolayer cultured on collagen-coated polyethylene terephthalate (PET) discs constituted the basic module for a hybrid liver support system. Freshly isolated rat hepatocytes were seeded on collagen-coated PET discs with a diameter of 33 mm at a density of 5x10(6) cells per disc, and were cultured for 24 h before cryopreservation. The total duration of procedure starting from exposure to low concentrations of cryoprotectants up to cryostorage is 10 min. Vitrification of the modules was achieved by using two vitrification solutions sequentially with first vitrification solution containing two cryoprotectants, ethylene glycol (EG) and sucrose, while second vitrification solution contained additionally polymer, Ficoll. Direct exposure to liquid nitrogen vapours was followed by immersion into liquid nitrogen. Recovery procedure for vitrified modules included their warming in 1m sucrose at temperature of 38-39 degrees C followed by subsequently washing in sucrose-based solutions of decreased concentration within 15 min at room temperature. Viability, structural characteristics, and functions of cells were preserved by vitrification. Hepatocytes in the post-vitrified and warmed monolayer maintained differentiated hepatocyte characteristics both structurally and functionally. In average, protein synthesis measured as albumin production was 181.00+/-33.46 ng/million cells and 166.10+/-28.11 ng/million cells, for control and vitrified modules respectively. Urea production was, in average, 1.52+/-0.40 ng/million cells and 1.36+/-0.31 ng/million cells for a 7 day culture respectively, with no significant statistical difference between the control and vitrified modules. PMID: 19477507 [PubMed - indexed for MEDLINE] |
| Controlled cyclic stretch bioreactor for tissue-engineered heart valves.
October 7, 2009 at 8:36 am
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| | Controlled cyclic stretch bioreactor for tissue-engineered heart valves. Biomaterials. 2009 Sep;30(25):4078-84 Authors: Syedain ZH, Tranquillo RT A tissue-engineered heart valve (TEHV) represents the ultimate valve replacement, especially for juvenile patients given its growth potential. To date, most TEHV bioreactors have been developed based on pulsed flow of culture medium through the valve lumen to induce strain in the leaflets. Using a strategy for controlled cyclic stretching of tubular constructs reported previously, we developed a controlled cyclic stretch bioreactor for TEHVs that leads to improved tensile and compositional properties. The TEHV is mounted inside a latex tube, which is then cyclically pressurized with culture medium. The root and leaflets stretch commensurately with the latex, the stretching being dictated by the stiffer latex and thus controllable. Medium is also perfused through the lumen at a slow rate in a flow loop to provide nutrient delivery. Fibrin-based TEHVs prepared with human dermal fibroblasts were subjected to three weeks of cyclic stretching with incrementally increasing strain amplitude. The TEHV possessed the tensile stiffness and stiffness anisotropy of leaflets from sheep pulmonary valves and could withstand cyclic pulmonary pressures with similar distension as for a sheep pulmonary artery. PMID: 19473698 [PubMed - indexed for MEDLINE] |
| Cryopreservable and tumorigenic three-dimensional tumor culture in porous poly(lactic-co-glycolic acid) microsphere.
October 7, 2009 at 8:36 am
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| | Cryopreservable and tumorigenic three-dimensional tumor culture in porous poly(lactic-co-glycolic acid) microsphere. Biomaterials. 2009 Sep;30(25):4227-32 Authors: Kang SW, Bae YH In vitro tumor models that mimic in vivo conditions may be ideal for screening anticancer drugs and their formulations and developing tumors in animal models. Three-dimensional (3-D) culture of cancer cells on polymeric scaffolds can be an option for such models. In the present study, porous poly(lactic acid-co-glycolic acid) (PLGA) microsphere was used both as a cancer cell culture substrate to expand cells and as a cancer cell transplantation vehicle for tumor construction in mice. MCF-7 cells cultured on porous PLGA microspheres in stirred suspension bioreactors expanded by 2.8-fold over seven days and maintained viability. At three months after inoculation with 2x10(6) cells/site, the tumor formation by MCF-7 cells cultured on microspheres was much more effective (4 tumors/5 mice) than its counterpart cultured on plates (1/5). More importantly, cell viability and metabolic activity were not significantly changed even after one freeze-thaw cycle of the 3-D culture. MCF-7 cells cultured on the microspheres and the cells in 3-D after cryopreservation were more resistant to doxorubicin than MCF-7 cells cultured on plates. PMID: 19446875 [PubMed - indexed for MEDLINE] |
| [Construction of human bone morphogenetic protein-7 gene fluorescent eukaryotic cell expression vector and test of bioactivity in vitro]
October 7, 2009 at 8:36 am
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| | [Construction of human bone morphogenetic protein-7 gene fluorescent eukaryotic cell expression vector and test of bioactivity in vitro] Zhonghua Kou Qiang Yi Xue Za Zhi. 2006 Apr;41(4):228-31 Authors: Yang XC, Fan MW OBJECTIVE: To construct fluorescent eukaryotic cell expression vector with human bone morphogenetic protein-7 (hBMP-7) gene and to transfect mouse stromal cell line W-20-17 to detect the bioactivity of pEGFP-hBMP-7 in vitro. METHODS: pEGFP-hBMP-7 plasmid was constructed by subcloning technique and identified by enzyme cutting and electrophoresis. W-20-17 cells were transfected with pEGFP-hBMP-7 by means of lipofectamine-2000 media methods. Transfection efficiency and gene expression were evaluated by fluorescent microscopy. ALP, von Kossa and osteocalcin (OC) were tested to determined the phenotypes of osteoblast. RESULTS: After 48 hours, the gene transfection efficiency was 40%. Based on GFP and immunofluorescence of pEGFP-hBMP-7, there was the expression of aim gene. After gene transfection, there were not significant different of cell morphology feature and cell proliferation. ALP activity, the number of calcium nodules and the expression of OC increased. CONCLUSIONS: pEGFP-hBMP-7 with bioactivity was constructed, which could induce W-20-17 cells to differentiate to osteoblasts. PMID: 16784590 [PubMed - indexed for MEDLINE] |
| [Repair of canine segmental mandibular defects using autogenous bone marrow stromal cells and coralline hydroxyapatite]
October 7, 2009 at 8:36 am
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| | [Repair of canine segmental mandibular defects using autogenous bone marrow stromal cells and coralline hydroxyapatite] Zhonghua Kou Qiang Yi Xue Za Zhi. 2006 Feb;41(2):94-7 Authors: Yuan J, Zhu L, Wang M, Cui L, Liu W, Cao YL OBJECTIVE: To repair segmental mandibular defects with autogenous bone marrow stromal cells (BMSCs) and coralline hydroxyapatite. METHODS: Isolated BMSCs were in vitro expanded and osteogenically induced. In 11 canines, a 3 cm segmental mandibular defect in right mandible was created. Five canine's defects were repaired with cell-scaffold constructs made from induced BMSCs and coralline hydroxyapatite (CHA); Others were repaired with CHA as control. The engineered bone was evaluated by X-ray, CT, gross and histological examination, biomechanical test 12, 26, 32 weeks post-operation respectively. RESULTS: BMSCs grew well on the CHA. X-ray and CT images showed better callus formation at connection sites in experimental group over time while worse formation at connection sites eventually in control group. At 32 weeks post-operation in experimental group, the defects were well repaired grossly. Histologically, there were bony healing and lamellar bone formation, in experimental group fibrous healing and woven bone formation in control group. Biomechanical test revealed no significant difference between experimental group and normal control group. CONCLUSIONS: Canine segmental mandibular defects can be ultimately repaired with the tissue-engineered bone generated by autogenous osteogenic BMSCs and CHA scaffold. PMID: 16640933 [PubMed - indexed for MEDLINE] | | | 
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