|  |  |  | | | | | TERMSC | | | | | | | | | | | | | | | | | | | The effect of ex vivo dynamic loading on the osteogenic differentiation of genetically engineered mesenchymal stem cell model. J Tissue Eng Regen Med. 2010 Aug 26; Authors: Kimelman-Bleich N, Seliktar D, Kallai I, Helm GA, Gazit Z, Gazit D, Pelled G Mechanical loading has been described as a highly important stimulus for improvements in the quality and strength of bone. It has also been shown that mechanical stimuli can induce the differentiation of mesenchymal stem cells (MSCs) along the osteogenic lineage. We have previously demonstrated the potent osteogenic effect of MSCs engineered to overexpress the BMP2 gene. In this study we investigated the effect of mechanical loading on BMP2-expressing MSC-like cells, using a special bioreactor designed to apply dynamic forces on cell-seeded hydrogels. Cell viability, alkaline phosphatase (ALP) activity, BMP2 secretion and mineralized substance formation in the hydrogels were quantified. We found that cell metabolism increased as high as 6.8-fold, ALP activity by 12.5-fold, BMP2 secretion by 182-fold and mineralized tissue formation by 1.72-fold in hydrogels containing MSC-like cells expressing BMP2, which were cultured in the presence of mechanical loading. We have shown that ex vivo mechanical loading had an additive effect on BMP2-induced osteogenesis in genetically engineered MSC-like cells. These data could be valuable for bone tissue-engineering strategies of the future. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20740691 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Protein polymer MRI contrast agents: Longitudinal analysis of biomaterials in vivo. Magn Reson Med. 2010 Aug 25; Authors: Karfeld-Sulzer LS, Waters EA, Kohlmeir EK, Kissler H, Zhang X, Kaufman DB, Barron AE, Meade TJ Despite recent advances in tissue engineering to regenerate biological function by combining cells with material supports, development is hindered by inadequate techniques for characterizing biomaterials in vivo. Magnetic resonance imaging is a tomographic technique with high temporal and spatial resolution and represents an excellent imaging modality for longitudinal noninvasive assessment of biomaterials in vivo. To distinguish biomaterials from surrounding tissues for magnetic resonance imaging, protein polymer contrast agents were developed and incorporated into hydrogels. In vitro and in vivo images of protein polymer hydrogels, with and without covalently incorporated protein polymer contrast agents, were acquired by magnetic resonance imaging. T(1) values of the labeled gels were consistently lower when protein polymer contrast agents were included. As a result, the protein polymer contrast agent hydrogels facilitated fate tracking, quantification of degradation, and detection of immune response in vivo. For the duration of the in vivo study, the protein polymer contrast agent-containing hydrogels could be distinguished from adjacent tissues and from the foreign body response surrounding the gels. The hydrogels containing protein polymer contrast agent have a contrast-to-noise ratio 2-fold greater than hydrogels without protein polymer contrast agent. In the absence of the protein polymer contrast agent, hydrogels cannot be distinguished by the end of the gel lifetime. Magn Reson Med, 2010. (c) 2010 Wiley-Liss, Inc. PMID: 20740653 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biocompatibility of poly(ethylene glycol)-based hydrogels in the brain: An analysis of the glial response across space and time. J Biomed Mater Res A. 2010 Oct;95(1):79-91 Authors: Bjugstad KB, Lampe K, Kern DS, Mahoney M Poly(ethylene glycol) or PEG-based hydrogels provide a useful methodology for tissue engineering and the controlled-release of drugs within the central nervous system (CNS). To be successful, the local neuroinflammatory response to an implant must be well understood. Toward this end, the focus was to examine the localized recruitment and activation of microglia and astrocytes following implantation of PEG-based hydrogels in the brain. Because they are of clinical relevance and may impact brain tissue differently, hydrogels with different mass loss profiles were examined. At all time points, a needle penetration in sham animals evoked a greater astrocytic response than hydrogel conditions. The astrocyte response that ensued varied with degradation rate. An attenuated response was present in more slowly degrading and nondegrading conditions. Relative to sham, hydrogel conditions attenuated the acute microglial response during the week after implant. By 56 days, microglial levels in shams decreased below the observed response in slowly degrading and nondegradable gels, which remained constant overtime. Although the inflammatory response to PEG-based hydrogels was complex depending on degradation rates, the magnitude of the acute microglia response and the long-term astrocyte response were attenuated suggesting the use of these materials for drug and cell delivery to the CNS. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20740603 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Electrospun nanofibrous matrix improves the regeneration of dense cortical bone. J Biomed Mater Res A. 2010 Oct;95(1):49-57 Authors: Cai YZ, Wang LL, Cai HX, Qi YY, Zou XH, Ouyang HW Numerous in vitro studies have indicated the potential of using electrospun nanofibrous scaffolds for tissue regeneration. However, few reports have demonstrated their utility in real tissue repair models. The present investigation tested the hypothesis that electrospun poly-L-lactic acid (PLLA) nanofibrous membrane leads to dense cortical bone regeneration and improves the efficacy of currently-used collagenous guided bone regeneration (GBR) membrane. In vitro, the function of bone marrow-derived mesenchymal stem cells (BMSCs) on nanofibrous scaffolds was evaluated. In an in vivo experiment, large bony defects were created in rabbit tibia and treated with a nanofiber-reinforced bilayer membrane, nanofibrous membrane, or collagenous membrane alone. Three and six weeks after operation, bone defect healing was assessed radiologically and histologically. In vitro differentiation studies showed that BMSCs had much higher expression of Runx2 and collagen type I, alpha 1 mRNAs, when cultured on nanofibrous scaffolds. The radiographic and histological data both showed that the group treated with bilayer membrane had more bony tissue formation at 3 weeks. Moreover, at 6 weeks, only the bilayer membrane-treated bone defects displayed better regeneration of cortical bone tissue, whereas in the other groups the defects were filled with spongy bone-like tissue. The results demonstrated that electrospun nanofibrous membrane improves the regeneration of cortical bone, suggesting that this type of membrane can be combined with current collagenous GBR membrane to improve guided bone regeneration technology. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20740600 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Proliferation and mineralization of bone marrow cells cultured on macroporous hydroxyapatite scaffolds functionalized with collagen type I for bone tissue regeneration. J Biomed Mater Res A. 2010 Oct;95(1):1-8 Authors: Teixeira S, Fernandes MH, Ferraz MP, Monteiro FJ This study concerns the preparation and in vitro characterization of functionalized hydroxyapatite (HA) porous scaffolds, which are intended to be used as drug-delivery systems and bone-regeneration matrices. Hydroxyapatite scaffolds were prepared using the polymer replication method, and, after being submitted to a specific sintering cycle, collagen Type I was incorporated on the surface. After the coating procedure, collagen was crosslinked using the N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) conjugation method. In this study, hydroxyapatite scaffolds with uncrosslinked and crosslinked Type I collagen were evaluated. Cell morphology and deposition of extracellular matrix were assessed by scanning electron microscopy, whereas cell distribution was visualized by means of methylene blue staining. MTS and total DNA quantification assays were used to evaluate the viability and proliferation of human bone marrow cells cultured on all the materials for 28 days. Results showed that the cells were able to adhere, proliferate, and form a mineralized matrix on the surface of all the materials. Furthermore, the cells were able to spread from one pore to another and form cell clusters. The results show that these scaffolds are good candidates to serve as drug delivery vehicles and for tissue engineering purposes. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010. PMID: 20740596 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Biological evaluation of solid freeformed, hard tissue scaffolds for orthopedic applications. J Appl Biomater Biomech. 2010 May-Aug;8(2):89-96 Authors: U Herath HM, Di Silvio L, Evans JR Purpose: Hydroxyapatite (HA) lattices were made by extrusion freeforming, a rapid prototyping process, and sintered to produce hard tissue scaffolds for bone regeneration. These highly reticulated lattice structures can be built directly from a computer design file which decides and controls their macroscopic shape, pore structure and size distribution. They are therefore defect-specific and show potential in tissue engineering for non-load bearing sites. Methods: Using a commercial human osteoblast-like cell line (HOS TE 85), biocompatibility was evaluated in an in vitro study. A high level of cell adhesion was evident by scanning electron microscopy on both convex and concave surfaces and the cell attachment was revealed at different depths into the scaffold. An AlamarBlue(R) assay was carried out to assess cell proliferation, which was further confirmed by quantifying total DNA concentration and total protein content. Results: The cell proliferation was significant and the pattern was comparable to that of the tissue culture control, ThermanoxTM. ALP activity and osteocalcin were quantified to evaluate the extent of cell differentiation, which confirmed the retention of the phenotype for the period studied. Mineralization of the matrix was determined via formation of nodules. Conclusions: HA scaffolds are non-toxic, able to maintain cell viability and support cell growth, proliferation, differentiation, and nodule formation. PMID: 20740471 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Cyclic mechanical stimulation favors myosin heavy chain accumulation in engineered skeletal muscle constructs. J Appl Biomater Biomech. 2010 May-Aug;8(2):68-75 Authors: Candiani G, Riboldi SA, Sadr N, Lorenzoni S, Neuenschwander P, Montevecchi FM, Mantero S Purpose: Since stretching plays a key role in skeletal muscle tissue development in vivo, by making use of an innovative bioreactor and a biodegradable microfibrous scaffold (DegraPol(R)) previously developed by our group, we aimed to investigate the effect of mechanical conditioning on the development of skeletal muscle engineered constructs, obtained by seeding and culturing murine skeletal muscle cells on electrospun membranes. Methods: Following 5 days of static culture, skeletal muscle constructs were transferred into the bioreactor and further cultured for 13 days, while experiencing a stretching pattern adapted from the literature to resemble mouse development and growth. Sample withdrawal occurred at the onset of cyclic stretching and after 7 and 10 days. Myosin heavy chain (MHC) accumulation in stretched constructs (D) was evaluated by Western blot analysis and immunofluorescence staining, using statically cultured samples (S) as controls. Results: Western blot analysis of MHC on dynamically (D) and statically (S) cultured constructs at different time points showed that, at day 10, the applied stretching pattern led to an eight-fold increase in myosin accumulation in cyclically stretched constructs (D) with respect to the corresponding static controls (S). These results were confirmed by immunofluorescence staining of total sarcomeric MHC. Conclusions: Since previous attempts to reproduce skeletal myogenesis in vitro mainly suffered from the difficulty of driving myoblast development into an architecturally organized array of myosin expressing myotubes, the chance of inducing MHC accumulation via mechanical conditioning represents a significant step towards the generation of a functional muscle construct for skeletal muscle tissue engineering applications. PMID: 20740468 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Polymer-based composite scaffolds for tissue engineering. J Appl Biomater Biomech. 2010 May-Aug;8(2):57-67 Authors: Gloria A, De Santis R, Ambrosio L Tissue engineering may be defined as the application of biological, chemical and engineering principles toward the repair, restoration or regeneration of living tissue using biomaterials, cells and biologically active molecules alone or in combinations. The rapid restoration of tissue biomechanical function represents a great challenge, highlighting the need to mimic tissue structure and mechanical behavior through scaffold designs. For this reason, several biodegradable and bioresorbable materials, as well as technologies and scaffold designs, have been widely investigated from an experimental and/or clinical point of view. Accordingly, this review aims at stressing the importance of polymer-based composite materials to make multifunctional scaffolds for tissue engineering, with a special focus on bone, ligaments, meniscus and cartilage. Moreover, polymer-based nanocomposites will also be briefly introduced as an interesting strategy to improve the biological and mechanical performances of polymer scaffolds, especially for bone tissue engineering. PMID: 20740467 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication of chemically cross-linked porous gelatin matrices. J Appl Biomater Biomech. 2009 Sep-Dec;7(3):194-9 Authors: Bozzini S, Petrini P, Altomare L, Tanzi MC Purpose: The aim of this study was to chemically cross-link gelatin, by reacting its free amino groups with an aliphatic diisocyanate. Methods: To produce hydrogels with controllable properties, the number of reacting amino groups was carefully determined. Porosity was introduced into the gelatin-based hydrogels through the lyophilization process. Porous and non-porous matrices were characterized with respect to their chemical structure, morphology, water uptake and mechanical properties. Results: The physical, chemical and mechanical properties of the porous matrices are related to the extent of their cross-linking, showing that they can be controlled by varying the reaction parameters. Water uptake values (24 hours) vary between 160% and 200% as the degree of cross-linking increases. The flexibility of the samples also decreases by changing the extent of cross-linking. Young's modulus shows values between 0.188 KPa, for the highest degree, and 0.142 KPa for the lowest degree. Conclusions: The matrices are potential candidates for use as tissue-engineering scaffolds by modulating their physical chemical properties according to the specific application. PMID: 20740429 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | 3D fiber deposition technique to make multifunctional and tailor-made scaffolds for tissue engineering applications. J Appl Biomater Biomech. 2009 Sep-Dec;7(3):141-52 Authors: Gloria A, Russo T, De Santis R, Ambrosio L Tissue engineering represents an interesting approach which aims to create tissues and organs de novo. In designing scaffolds for tissue engineering applications, the principal goal is to mimic the function of the natural extracellular matrix, providing a temporary template for the growth of target tissues. For this reason, scaffolds should possess suitable mechanical properties and architecture to play their specific role. In this paper, limitations of conventional scaffold fabrication methods will be briefly introduced, and rapid prototyping techniques will be described as advanced processing methods to realize customized scaffolds with controlled internal microarchitecture. Among the rapid prototyping techniques, the potential and challenges of 3D fiber deposition to create multifunctional and tailor-made scaffolds will be reviewed. PMID: 20740423 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Comparison of Candidate Materials for a Synthetic Osteo-Odonto Keratoprosthesis (OOKP) device. Invest Ophthalmol Vis Sci. 2010 Aug 25; Authors: Tan XW, Perera AP, Tan A, Tan DT, Khor KA, Beuerman RW, Mehta JS Purpose: Osteo-Odonto Keratoprosthesis (OOKP) is one of the most successful forms of keratoprosthesis surgery for end stage corneal and ocular surface disease. There is a lack of detailed comparison studies on the biocompatibilities of different materials used in keratoprosthesis. The aim of this investigation is to compare synthetic bioinert materials used for keratoprosthesis surgery with hydroxyapatite (HA) as a reference. Methods: Test materials were sintered titanium oxide (TiO2), aluminum oxide (Al2O3) and yttria-stabilized zirconia (YSZ) with density >95%. Bacteria adhesion on the substrates was evaluated using scanning electron microscopy and the spread plate METHOD: Surface properties of the implant discs were scanned using optical microscopy. Human keratocyte attachment and proliferation rates were assessed by cell counting and MTT assay at different time points. Morphological analysis and immunoblotting was used to evaluate focal adhesion formation while cell adhesion force was measured with a multimode atomic force microscope (AFM). Results: We found that bacterial adhesion on the TiO2, Al2O3, and YSZ surfaces were lower compared to that on HA substrates. TiO2 significantly promoted keratocytes proliferation and viability compared with HA, Al2O3, and YSZ. Immunofluorescent imaging analyses, immunoblotting and atomic force microscope measurement revealed that TiO2 surfaces enhanced cell spreading and cell adhesion compared to HA and Al2O3. Conclusions: TiO2 is the most suitable replacement candidate for use as skirt material as it enhanced cell functions and reduced bacterial adhesion. This would in turn enhance tissue integration and reduce device failure rates during keratoprosthesis surgery. PMID: 20739467 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | The mechanical characteristics and in vitro biocompatibility of poly(glycerol sebacate)-Bioglass((R)) elastomeric composites. Biomaterials. 2010 Aug 24; Authors: Liang SL, Cook WD, Thouas GA, Chen QZ Biodegradable elastomeric materials have gained much recent attention in the field of soft tissue engineering. Poly(glycerol sebacate) (PGS) is one of a new family of elastomers which are promising candidates used for soft tissue engineering. However, PGS has a limited range of mechanical properties and has drawbacks, such as cytotoxicity caused by the acidic degradation products of very soft PGS and degradation kinetics that are too fast in vivo to provide sufficient mechanical support to the tissue. However, the development of PGS/based elastomeric composites containing alkaline bioactive fillers could be a method for addressing these drawbacks and thus may pave the way towards wide clinical applications. In this study, we synthesized a new PGS composite system consisting of a micron-sized Bioglass((R)) filler. In addition to much improved cytocompatibility, the PGS/Bioglass((R)) composites demonstrated three remarkable mechanical properties. First, contrary to previous reports, the addition of microsized Bioglass((R)) increases the elongation at break from 160 to 550%, while enhancing the Young's modulus of the composites by up to a factor of four. Second, the modulus of the PGS/Bioglass((R)) composites drops abruptly in a physiological environment (culture medium), and the level of drop can be tuned such that the addition of Bioglass((R)) does not harden the composite in vivo and thus the desired compliance required for soft tissue engineering are maintained. Third, after the abrupt drop in modulus, the composites exhibited mechanical stability over an extended period. This latter observation is an important feature of the new composites, because they can provide reliable mechanical support to damaged tissues during the lag phase of the healing process. These mechanical properties, together with improved biocompatibility, make this family of composites better candidates than plastic and related composite biomaterials for the applications of tissue engineering. PMID: 20739061 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Ultraviolet light crosslinking of poly(trimethylene carbonate) for elastomeric tissue engineering scaffolds. Biomaterials. 2010 Aug 23; Authors: Bat E, Kothman BH, Higuera GA, van Blitterswijk CA, Feijen J, Grijpma DW A practical method of photocrosslinking high molecular weight poly(trimethylene carbonate)(PTMC) is presented. Flexible, elastomeric and biodegradable networks could be readily prepared by UV irradiating PTMC films containing pentaerythritol triacrylate (PETA) and a photoinitiator. The network characteristics, mechanical properties, wettability, and in vitro enzymatic erosion of the photocrosslinked PTMC films were investigated. Densely crosslinked networks with gel contents up to 98% could be obtained in this manner. Upon photocrosslinking, flexible and tough networks with excellent elastomeric properties were obtained. To illustrate the ease with which the properties of the networks can be tailored, blends of PTMC with mPEG-PTMC or with PTMC-PCL-PTMC were also photocrosslinked. The wettability and the enzymatic erosion rate of the networks could be tuned by blending with block copolymers. Tissue engineering scaffolds were also fabricated using these flexible photocrosslinkable materials. After crosslinking, the fabricated PTMC-based scaffolds showed inter-connected pores and extensive microporosity. Human mesenchymal stem cell (hMSC) culturing studies showed that the photocrosslinked scaffolds prepared from PTMC and PTMC/PTMC-PCL-PTMC blends are well-suited for tissue engineering applications. PMID: 20739060 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Redefining tissue engineering for nanomedicine in ophthalmology. Acta Ophthalmol. 2010 Aug 25; Authors: Ellis-Behnke R, Jonas JB Abstract. Working at the nanoscale means to completely rethink how to approach engineering in the body in general and in the eye in particular. In nanomedicine, tissue engineering is the ability to influence an environment either by adding, subtracting or manipulating that environment to allow it to be more conducive for its purpose. The goal is to function at the optimum state, or to return to that optimum state. Additive tissue engineering replaces cells or tissue, or tries to get something to grow that is no longer there. Arrestive tissue engineering tries to stop aberrant growth which, if left uncontrolled, would result in a decrease in function. Nano delivery of therapeutics can perform both additive and arrestive functions influencing the environment either way, depending on the targeting. By manipulating the environment at the nanoscale, the rate and distribution of healing can be controlled. It infers that potential applications of nanomedicine in ophthalmology include procedures, such as corneal endothelial cell transplantation, single retinal ganglion cell repair, check of retinal ganglion cell viability, building of nanofibre scaffolds, such as self-assembling peptides, to create a scaffold-like tissue-bridging structure to provide a framework for axonal regeneration in the case of optic nerve reconnection or eye transplantation, and ocular drug delivery. Examples of potential arrestive therapies include gene-related treatment modalities to inhibit intraocular neovascularization and to block retinal cell apoptosis. Looking towards the future, this review focuses on how nanoscale tissue engineering can be and is being used to influence that local environment. PMID: 20738260 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Assessing the immunopotency of Toll-like receptor agonists in an in vitro tissue-engineered immunological model. Immunology. 2010 Jul;130(3):374-87 Authors: Ma Y, Poisson L, Sanchez-Schmitz G, Pawar S, Qu C, Randolph GJ, Warren WL, Mishkin EM, Higbee RG SUMMARY: The in vitro Peripheral Tissue Equivalent (PTE) module is a three-dimensional tissue-engineered endothelial cell/collagen matrix culture system, which has been reported to reproduce in vivo physiological conditions and which generates dendritic cells (DC) autonomously. In the present study, we used the PTE module to investigate the immunopotency of Toll-like receptor (TLR) agonists, including polyinosine-polycytidylic acid, Gardiquimod, CpG 2006 and lipopolysaccharide. Application of TLR agonists in the PTE module induced a wide range of cytokines, including interleukins 1alpha/beta, 6, 8 and 10 and tumour necrosis factor-alpha. Compared with traditional peripheral blood mononuclear cell (PBMC) cultures, the PTE module produced twofold to 100-fold higher levels of cytokine secretion, indicating that it can be a highly sensitive assay system. This increased sensitivity is the result of the natural synergy between the leucocytes and the endothelium. Furthermore, the application of TLR agonists, such as lipopolysaccharide and Gardiquimod, to the PTE module enhanced DC differentiation and promoted DC maturation, as indicated by up-regulated expression of CD83, CD86 and CCR7(CD197). In addition, functional assays indicated PTE-derived DC treated with Gardiquimod, a TLR-7 agonist, significantly augmented anti-tetanus toxoid antibody production. Interestingly, replacing PBMC with purified myeloid cells (CD33(+)) significantly reduced the responsiveness of the PTE module to TLR stimulation. The reduced sensitivity was partly the result of the removal of plasmacytoid DC that participated in the response to TLR stimulation and sensitization of the PTE module. Overall, the in vitro PTE module clearly demonstrated the effects of TLR agonists on DC generation, maturation and antigen-presenting capacity, and may serve as a sensitive and predictive test bed for the evaluation of adjuvant candidates. PMID: 20331478 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Bladder wall transplantation--long-term survival of cells: implications for bioengineering and clinical application. Tissue Eng Part A. 2010 Jun;16(6):2121-7 Authors: Tanaka ST, Thangappan R, Eandi JA, Leung KN, Kurzrock EA Current bioengineered bladder wall substitutes include acellular scaffolds and grafts seeded with autologous cells. The transplanted cells on a seeded graft may regenerate and/or be replaced by cells of the patient's bladder. This may or may not be advantageous depending upon the underlying pathology. A theoretically perfect bioengineered graft would be intact bladder wall. To determine if such a graft is feasible and to study the cellular changes, we transplanted full-thickness bladder grafts from male inbred rats onto bladders of female syngeneic rats. Bladders were harvested at 1, 3, 6, 12, and 16 months after surgery and evaluated for histologic changes. Cell origin (male donor vs. female host) was determined with fluorescent in situ hybridization with unique probes for rat X and Y chromosomes. Urothelial hyperplasia, inflammation, and increased stromal thickness subsided down to control values by 6 months after surgery. At 16 months, graft muscle demonstrated persistence of male cells. On the other hand, graft urothelium was partially replaced by female host cells with a pattern suggestive of a hematogenous route rather than ingrowth from the host bladder. Bladder wall transplantation is feasible. The slow replacement of the transplanted urothelium and persistence of muscle may imply the same fate for engineered grafts. PMID: 20109058 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Ex vivo construction of an artificial ocular surface by combination of corneal limbal epithelial cells and a compressed collagen scaffold containing keratocytes. Tissue Eng Part A. 2010 Jun;16(6):2091-100 Authors: Mi S, Chen B, Wright B, Connon CJ We have investigated the use of a laminin-coated compressed collagen gel containing corneal fibroblasts (keratocytes) as a novel scaffold to support the growth of corneal limbal epithelial stem cells. The growth of limbal epithelial cells was compared between compressed collagen gel and a clinically proven conventional substrate, denuded amniotic membrane (AM). Following compression of the collagen gel, encapsulated keratocytes remained viable and scanning electron microscopy showed that fibers within the compressed gel were dense, homogeneous, and similar in structure to those within denuded AM. Limbal epithelial cells were successfully expanded upon the compressed collagen, resulting in stratified layers of cells containing desmosome and hemidesmosome structures. The resulting corneal constructs of both the groups shared a high degree of transparency, cell morphology, and cell stratification. Similar protein expression profiles for cytokeratin 3 (CK3) and CK14 and no significant difference in CK12 mRNA expression levels by real-time polymerase chain reaction were also observed. This study provides the first line of evidence that a laminin-coated compressed collagen gel containing keratocytes can adequately support limbal epithelial cell expansion, stratification, and differentiation to a degree that is comparable to the leading conventional scaffold, denuded AM. PMID: 20109018 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Recombinant gelatin microspheres: novel formulations for tissue repair? Tissue Eng Part A. 2010 Jun;16(6):1811-21 Authors: Tuin A, Kluijtmans SG, Bouwstra JB, Harmsen MC, Van Luyn MJ Microspheres (MSs) can function as multifunctional scaffolds in different approaches of tissue repair (TR), as a filler, a slow-release depot for growth factors, or a delivery vehicle for cells. Natural cell adhesion-supporting extracellular matrix components like gelatin are good materials for these purposes. Recombinant production of gelatin allows for on-demand design of gelatins, which is why we aim at developing recombinant gelatin (RG) MSs for TR. Two types of MSs (50 < Ø < 100 microm) were prepared by crosslinking two RGs, Syn-RG, and the arginine-glycine-aspartate-containing Hu-RG. The MSs were characterized, and their tissue reaction and degradation in rats was examined. Histological analysis of the explants after 14 and 28 days in vivo also showed that Syn-RG was degraded slower than Hu-RG, which correlated with the in vitro degradation assay. Hu-RG explants displayed more cellular ingrowth (60% vs. 15% for Syn-RG at day 14), which was associated with extracellular matrix deposition and vascularization. The infiltrating cells consisted of mainly macrophages, part of which fused to giant cells locally, and fibroblasts. No differences were found in matrix metalloproteinase mRNA levels, whereas gelatinase activity was clearly higher in Hu-RG explants. In conclusion, the in vitro and in vivo results of these novel formulations pave the way for cell- and/or factor-driven TR by these RG MSs. PMID: 20102269 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Formation of hepatocyte spheroids with structural polarity and functional bile canaliculi using nanopillar sheets. Tissue Eng Part A. 2010 Jun;16(6):1983-95 Authors: Takahashi R, Sonoda H, Tabata Y, Hisada A We developed a method for controlling the spheroid formation of adult rat primary hepatocytes simply by optimizing the pillar diameters and patterns of nanopillar sheets. To investigate the effects of the pillar parameters on the spheroid formation, rat primary hepatocytes were cultured on nanopillar sheets with pillars that had one of five different diameters and that had been precoated with a solution containing one of two different concentrations of type I collagen. Spheroids with a compact morphology that were adhesive to the substratum and had an optimal size (50 to 100 microm) were obtained using a sheet with a pillar diameter of 2.0 microm that was precoated with 100 ng/mL of type I collagen solution. Immunohistochemistry revealed that the spheroids had a structure similar to that of native liver tissue. We then assessed the effect of overlaying reconstituted spheroids with Matrigel with the aim of achieving a simulated in vivo environment. The mRNA expression levels of MRP2, albumin, and P450-3A3 for spheroids determined by semiquantitative real-time PCR were significantly higher than those for spheroids cultured without the Matrigel overlay or for hepatocytes cultured using a conventional two-dimensional method. The spheroids obtained exhibited higher structural polarity and functional bile canaliculi compared with hepatocytes cultured using a conventional two-dimensional method. PMID: 20100035 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Endothelial progenitor cells and mesenchymal stem cells seeded onto beta-TCP granules enhance early vascularization and bone healing in a critical-sized bone defect in rats. Tissue Eng Part A. 2010 Jun;16(6):1961-70 Authors: Seebach C, Henrich D, Kähling C, Wilhelm K, Tami AE, Alini M, Marzi I QUESTION/AIM: Lack of vessels indicates an insufficient nutritional supply of a bone graft and may limit the recruitment of bone-forming cells. Our aim was to evaluate the influence of endothelial progenitor cells (EPCs) alone or in combination with mesenchymal stem cells (MSCs) on early vascularization and bone healing in critical-sized defect (CSD) in vivo. METHODS: MSCs from human bone marrow and EPCs from buffy coat were used. A femoral CSD in adult athymic rats was created and stabilized by an external fixateur. The remaining defects were filled with fibronectin-coated beta-tricalcium phosphate (beta-TCP) granules, EPCs seeded on beta-TCP, MSCs seeded on beta-TCP, coculture of EPCs/MSCs seeded on beta-TCP, or autologous bone. Vascularization and bone formation were determined by immunohistology, microCT analysis, and biomechanical testing after 1, 4, and 8 weeks. RESULTS: Early vascularization was significantly improved in EPC/MSC group or EPC group, respectively. At 4 weeks bone formation increased significantly when the CSD was treated with coculture of MSCs/EPCs. Eight weeks after transplantation CSD showed significantly more bony bridgings and significantly increased ultimate load in the EPC/MSC group compared to the other groups. DISCUSSION: This cell approach suggests that there is a synergistic effect and that the initial stage of neovascularization by EPCs is considered to be crucial for complete bone regeneration in the late phase. PMID: 20088701 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Scaffold-free in vitro arterial mimetics: the importance of smooth muscle-endothelium contact. Tissue Eng Part A. 2010 Jun;16(6):1901-12 Authors: Chaterji S, Park K, Panitch A We have developed an in vitro endothelial cell (EC)-smooth muscle cell (SMC) coculture platform that can mimic either the healthy or diseased state of blood vessels. Transforming growth factor-beta1 (TGF-beta1) and heparin were introduced to the SMC cultures to upregulate the SMC differentiation markers, alpha-smooth muscle actin (alpha-SMA) and calponin (homotypic model). Interestingly, seeding of near-confluent concentrations of ECs on the SMCs (heterotypic model) induced higher levels of alpha-SMA and calponin expression in the SMC cultures than did the addition of heparin and TGF-beta1 alone. The expression levels increased further on pretreating the SMCs with TGF-beta1 and heparin before adding a near-confluent monolayer of ECs. In contrast, seeding of sparse concentrations of ECs forced the SMCs into a more hyperplastic state as determined by alpha-SMA and calponin expression. This study highlights the importance of both soluble factors and EC seeding densities when considering culture conditions; in vivo SMCs are in close proximity with and interact with a monolayer of ECs. Our study suggests that this architecture is important for healthy vascular tissue function. In addition, it shows that disruption of this architecture can be used to mimic diseased states. As the EC-SMC coculture model can mimic either a diseased or a healthy blood vessel it may be useful as a test bed for evaluating cardiovascular therapeutics. PMID: 20088699 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Impact of degradable macromer content in a poly(ethylene glycol) hydrogel on neural cell metabolic activity, redox state, proliferation, and differentiation. Tissue Eng Part A. 2010 Jun;16(6):1857-66 Authors: Lampe KJ, Bjugstad KB, Mahoney MJ Hydrogels that degrade at different rates were prepared by copolymerizing slowly degrading macromer poly(ethylene glycol) (PEG) dimethacrylate with a faster degrading macromer poly(lactic acid)-b-PEG-b-poly(lactic acid) dimethacrylate. A clinically relevant population of neural cells composed of differentiated neurons and multipotent precursor cells was cultured within hydrogels. Within 2 h after encapsulation, metabolic activity was higher in hydrogels prepared with increasing levels of degradable content. This improvement was accompanied by a reduction in intracellular redox state and an increase in the fraction of glutathione in the reduced state, both of which persisted throughout 7 days of culture and which may be the result of radical scavenging by lactic acid. Importantly, an increase in cellular proliferation was observed in gels prepared with increasing degradable macromer content after 7 days of growth without a shift in the cellular composition of the culture toward the glial cell phenotype. The findings of this study provide additional insight into the growth of neural cells in PEG-based hydrogels. Results suggest that lactic acid released during gel degradation may impact the function of encapsulated cells, a finding of general interest to biomaterials scientists who focus on the development of degradable polymers for cell culture and drug delivery devices. PMID: 20067398 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Effect of dynamic stiffness of the substrates on neurite outgrowth by using a DNA-crosslinked hydrogel. Tissue Eng Part A. 2010 Jun;16(6):1873-89 Authors: Jiang FX, Yurke B, Schloss RS, Firestein BL, Langrana NA Central nervous system tissues, like other tissue types, undergo constant remodeling, which potentially leads to changes in their mechanical stiffness. Moreover, mechanical compliance of central nervous system tissues can also be modified under external load such as that experienced in traumatic brain or spinal cord injury, and during pathological processes. Thus, the neuronal responses to the dynamic stiffness of the microenvironment are of significance. In this study, we induced decrease in stiffness by using a DNA-crosslinked hydrogel, and subjected rat spinal cord neurons to such dynamic stiffness. The neurons respond to the dynamic cues as evidenced by the primary neurite structure, and the response from each neurite property (e.g., axonal length and primary dendrite number) is consistent with the behavior on static gels of same substrate rigidity, with one exception of mean primary dendrite length. The results on cell population distribution confirm the neuronal responses to the dynamic stiffness. Quantification on the focal adhesion kinase expression in the neuronal cell body on dynamic gels suggests that neurons also modify adhesion in coping with the dynamic stiffnesses. The results reported here extend the neuronal mechanosensing capability to dynamic stiffness of extracellular matrix, and give rise to a novel way of engineering neurite outgrowth in time dimension. PMID: 20067396 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Porcine endothelial cells cocultured with smooth muscle cells became procoagulant in vitro. Tissue Eng Part A. 2010 Jun;16(6):1835-44 Authors: Pang Z, Niklason LE, Truskey GA Endothelial cell (EC) seeding represents a promising approach to provide a nonthrombogenic surface on vascular grafts. In this study, we used a porcine EC/smooth muscle cell (SMC) coculture model that was previously developed to examine the efficacy of EC seeding. Expression of tissue factor (TF), a primary initiator in the coagulation cascade, and TF activity were used as indicators of thrombogenicity. Using immunostaining, primary cultures of porcine EC showed a low level of TF expression, but a highly heterogeneous distribution pattern with 14% of ECs expressing TF. Quiescent primary cultures of porcine SMCs displayed a high level of TF expression and a uniform pattern of staining. When we used a two-stage amidolytic assay, TF activity of ECs cultured alone was very low, whereas that of SMCs was high. ECs cocultured with SMCs initially showed low TF activity, but TF activity of cocultures increased significantly 7-8 days after EC seeding. The increased TF activity was not due to the activation of nuclear factor kappa-B on ECs and SMCs, as immunostaining for p65 indicated that nuclear factor kappa-B was localized in the cytoplasm in an inactive form in both ECs and SMCs. Rather, increased TF activity appeared to be due to the elevated reactive oxygen species levels and contraction of the coculture, thereby compromising the integrity of EC monolayer and exposing TF on SMCs. The incubation of cocultures with N-acetyl-cysteine (2 mM), an antioxidant, inhibited contraction, suggesting involvement of reactive oxygen species in regulating the contraction. The results obtained from this study provide useful information for understanding thrombosis in tissue-engineered vascular grafts. PMID: 20055662 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A comparison of bioreactors for culture of fetal mesenchymal stem cells for bone tissue engineering. Biomaterials. 2010 Aug 24; Authors: Zhang ZY, Teoh SH, Teo EY, Khoon Chong MS, Shin CW, Tien FT, Choolani MA, Chan JK Bioreactors provide a dynamic culture system for efficient exchange of nutrients and mechanical stimulus necessary for the generation of effective tissue engineered bone grafts (TEBG). We have shown that biaxial rotating (BXR) bioreactor-matured human fetal mesenchymal stem cell (hfMSC) mediated-TEBG can heal a rat critical sized femoral defect. However, it is not known whether optimal bioreactors exist for bone TE (BTE) applications. We systematically compared this BXR bioreactor with three most commonly used systems: Spinner Flask (SF), Perfusion and Rotating Wall Vessel (RWV) bioreactors, for their application in BTE. The BXR bioreactor achieved higher levels of cellularity and confluence (1.4-2.5x, p < 0.05) in large 785 mm(3) macroporous scaffolds not achieved in the other bioreactors operating in optimal settings. BXR bioreactor-treated scaffolds experienced earlier and more robust osteogenic differentiation on von Kossa staining, ALP induction (1.2-1.6x, p < 0.01) and calcium deposition (1.3-2.3x, p < 0.01). We developed a Micro CT quantification method which demonstrated homogenous distribution of hfMSC in BXR bioreactor-treated grafts, but not with the other three. BXR bioreactor enabled superior cellular proliferation, spatial distribution and osteogenic induction of hfMSC over other commonly used bioreactors. In addition, we developed and validated a non-invasive quantitative micro CT-based technique for analyzing neo-tissue formation and its spatial distribution within scaffolds. PMID: 20739062 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Polysaccharide-based materials for cartilage tissue engineering applications. J Tissue Eng Regen Med. 2010 Aug 26; Authors: Oliveira JT, Reis RL Tissue engineering was proposed approximately 15 years ago as an alternative and innovative way to address tissue regeneration problems. During the development of this field, researchers have proposed a variety of ways of looking into the regeneration and engineering of tissues, using different types of materials coupled with a wide range of cells and bioactive agents. This trilogy is commonly considered the basis of a tissue-engineering strategy, meaning by this the use of a support material, cells and bioactive agents. Different researchers have been adding to these basic approaches other parameters able to improve the functionality of the tissue-engineered construct, such as specific mechanical environments and conditioned gaseous atmospheres, among others. Nowadays, tissue-engineering principles have been applied, with different degrees of success, to almost every tissue lacking efficient regeneration ability and the knowledge and intellectual property produced since then has experienced an immense growth. Materials for regenerating tissues, namely cartilage, have also been continuously increasing and most of the theoretical requirements for a tissue engineering support have been addressed by a single material or a mixture of materials. Due to their intrinsic features, polysaccharides are interesting for cartilage tissue-engineering approaches and as a result their exploitation for this purpose has been increasing. The present paper intends to provide an overview of some of the most relevant polysaccharides used in cartilage tissue-engineering research. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20740689 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Preparation of keratinocyte culture medium for the clinical applications of regenerative medicine. J Tissue Eng Regen Med. 2010 Aug 26; Authors: Takagi R, Yamato M, Murakami D, Kondo M, Yang J, Ohki T, Nishida K, Kohno C, Okano T Keratinocyte culture medium (KCM) has been used for the in vitro culture of keratinocytes and other types of epithelial cells, and the medium includes various ingredients. In this study, two modified KCMs were prepared. In the first, insulin, hydrocortisone and antibiotics that are normally included in KCM were replaced with clinically approved pharmaceutical agents, except transferrin and selenium; in the second, cholera toxin (CT) was replaced by L-isoproterenol (ISO). The modified KCMs were then compared to conventional KCM containing laboratory-grade reagents. Induced cell colony formations of canine oral mucosal epithelial cells cultured in both modified KCMs were found to be nearly equivalent to that in the control KCM, and there was no significant difference between the effect of CT and ISO. Canine oral mucosal cells proliferated to confluence in all three KCM formulations, with or without the use of 3T3 feeder layers. Cultured epithelial cells were harvested from temperature-responsive culture surfaces as an intact cell sheet, and the immunohistochemical analysis of the sheets showed that p63 and cytokeratin were expressed in the epithelial cell sheets cultured in all KCMs. Eventually, in the modified KCM formula, fetal bovine serum was replaced by autologous human serum, and the formula was found to be able to fabricate human oral mucosal epithelial cell sheets. These results indicated that the modified KCM was equally efficient as conventional KCM in the fabrication of transplantable stratified epithelial cell sheets. Copyright (c) 2010 John Wiley & Sons, Ltd. PMID: 20740688 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Bridging the gap: Bone marrow aspiration concentrate reduces autologous bone grafting in osseous defects. J Orthop Res. 2010 Aug 25; Authors: Jäger M, Herten M, Fochtmann U, Fischer J, Hernigou P, Zilkens C, Hendrich C, Krauspe R Although autologous bone grafting represents an effective tool to induce osteogenic regeneration in local bone defects or pseudarthroses, it is associated with significant donor site morbidity and limited by the amount available for grafting. We investigate the potency of bone marrow aspiration concentrate (BMAC) to augment bone grafting and support bone healing. The functional and radiographic outcome of 39 patients with volumetric bone deficiencies treated with BMAC are presented and evaluated in a prospective clinical trial. A collagen sponge (Col) served as scaffold in 12 patients and a bovine hydroxyapatite (HA) was applied in the other 27 individuals. The minimal follow-up was 6 months. Clinical and radiographic findings were completed by in vitro data. All patients showed new bone formation in radiographs during follow-up. However, two patients underwent revision surgery due to a lack in bone healing. In contrast to the Col group, the postoperative bone formation appeared earlier in the HA group (HA group: 6.8 weeks vs. Col group 13.6 weeks). Complete bone healing was achieved in the HA group after 17.3 weeks compared to 22.4 weeks in the Col group. The average concentration factor of BMAC was 5.2 (SD 1.3). Flow cytometry confirmed the mesenchymal nature of the cells. Cells from BMAC created earlier and larger colonies of forming units fibroblasts (CFU-F) compared to cells from bone marrow aspirate. BMAC combined with HA can reduce the time needed for healing of bone defects when compared to BMAC in combination with collagen sponge. J. Orthop. Res. (c) 2010 Orthopaedic Research Society. PMID: 20740672 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Collagen oligomers modulate physical and biological properties of three-dimensional self-assembled matrices. Biopolymers. 2010 Aug 24; Authors: Bailey JL, Critser PJ, Whittington C, Kuske JL, Yoder MC, Voytik-Harbin SL Elucidation of mechanisms underlying collagen fibril assembly and matrix-induced guidance of cell fate will contribute to the design and expanded use of this biopolymer for research and clinical applications. Here, we define how type I collagen oligomers affect in-vitro polymerization kinetics as well as fibril microstructure and mechanical properties of formed matrices. Monomers and oligomers were fractionated from acid-solubilized pig skin collagen and used to generate formulations varying in monomer/oligomer content or average polymer molecular weight (AMW). Polymerization half-times decreased with increasing collagen AMW and closely paralleled lag times, indicating that oligomers effectively served as nucleation sites. Furthermore, increasing AMW yielded matrices with increased interfibril branching and had no correlative effect on fibril density or diameter. These microstructure changes increased the stiffness of matrices as evidenced by increases in both shear storage and compressive moduli. Finally, the biological relevance of modulating collagen AMW was evidenced by the ability of cultured endothelial colony forming cells to sense associated changes in matrix physical properties and alter vacuole and capillary-like network formation. This work documents the importance of oligomers as another physiologically-relevant design parameter for development and standardization of polymerizable collagen formulations to be used for cell culture, regenerative medicine, and engineered tissue applications. (c) 2010 Wiley Periodicals, Inc. Biopolymers, 2010. PMID: 20740490 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | High frequencies of leukemia stem cells in poor-outcome childhood precursor-B acute lymphoblastic leukemias. Leukemia. 2010 Aug 26; Authors: Morisot S, Wayne AS, Bohana-Kashtan O, Kaplan IM, Gocke CD, Hildreth R, Stetler-Stevenson M, Walker RL, Davis S, Meltzer PS, Wheelan SJ, Brown P, Jones RJ, Shultz LD, Civin CI In order to develop a xenograft model to determine the efficacy of new therapies against primary human precursor-B acute lymphoblastic leukemia (ALL) stem cells (LSCs), we used the highly immunodeficient non-obese diabetic (NOD).Cg-Prkdc(scid)IL2rg(tmlWjl)/SzJ (NOD-severe combined immune deficient (scid) IL2rg(-/-)) mouse strain. Intravenous transplantation of 2 of 2 ALL cell lines and 9 of 14 primary ALL cases generated leukemia-like proliferations in recipient mice by 1-7 months after transplant. Leukemias were retransplantable, and the immunophenotypes, gene rearrangements and expression profiles were identical or similar to those of the original primary samples. NOD-scid mice transplanted with the same primary samples developed similar leukemias with only a slightly longer latency than did NOD-scid-IL2Rg(-/-) mice. In this highly sensitive NOD-scid-IL2Rg(-/-)-based assay, 1-100 unsorted primary human ALL cells from five of five tested patients, four of whom eventually experienced leukemia relapse, generated leukemias in recipient mice. This very high frequency of LSCs suggests that a hierarchical LSC model is not valuable for poor-outcome ALL.Leukemia advance online publication, 26 August 2010; doi:10.1038/leu.2010.184. PMID: 20739953 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | From skin cells to hepatocytes: advances in application of iPS cell technology. J Clin Invest. 2010 Aug 25; Authors: Greenbaum LE The discovery several years ago that fibroblasts and other somatic cells from mice and humans can be reprogrammed to become inducible pluripotent stem (iPS) cells has created enthusiasm for their potential applications in regenerative medicine and for modeling human diseases. Two independent studies in this issue of the JCI provide evidence that iPS cells represent a promising source of hepatocytes for a wide range of applications, including cell transplantation, drug toxicity testing, patient-specific disease modeling, and even ex vivo gene therapy. But how far have we come? PMID: 20739747 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Generation of Bioengineered Corneas with Decellularized Xenografts and Human Keratocytes. Invest Ophthalmol Vis Sci. 2010 Aug 25; Authors: Gonzalez-Andrades M, Cardona JD, Ionescu AM, Campos A, Perez MD, Alaminos M Purpose: Decellularization of animal corneas is a promising method for the development of artificial human corneas by tissue engineering. In this study, we have evaluated two different decellularization protocols to determine which one is able to best preserve the histological structure, composition and optical behavior of decellularized porcine corneas. Then, these corneas were recellularized with human keratocytes in order to obtain a partial human corneal substitute. Methods: We have applied two different decellularization protocols using NaCl and SDS to determine which one is able to best preserve the histological structure, composition and optical behavior of the decellularized corneas Then, those decellularized corneas that showed the most appropriate results were recellularized with human keratocytes and evaluated at the histological, biochemical and optical levels for use in regenerative medicine. Results: Our results showed that 1.5 M NaCl treatment of porcine corneas is able to generate an acellular corneal stroma with adequate histological and optical properties, and that human keratocytes are able to penetrate and spread within this scaffold with proper levels of cell differentiation. In contrast, 0.1% SDS treatment of porcine corneas resulted in high levels of fibrils disorganization and poor optical behavior of these corneas. Conclusions: In conclusion, we suggest that the decellularization of animal corneas using 1.5 M NaCl represents a useful method for the development of human bioengineered corneas with therapeutic potential. PMID: 20739475 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Biological characteristics of stem cells from foetal, cord blood and extraembryonic tissues. J R Soc Interface. 2010 Aug 25; Authors: Abdulrazzak H, Moschidou D, Jones G, Guillot PV Foetal stem cells (FSCs) can be isolated during gestation from many different tissues such as blood, liver and bone marrow as well as from a variety of extraembryonic tissues such as amniotic fluid and placenta. Strong evidence suggests that these cells differ on many biological aspects such as growth kinetics, morphology, immunophenotype, differentiation potential and engraftment capacity in vivo. Despite these differences, FSCs appear to be more primitive and have greater multi-potentiality than their adult counterparts. For example, foetal blood haemopoietic stem cells proliferate more rapidly than those found in cord blood or adult bone marrow. These features have led to FSCs being investigated for pre- and post-natal cell therapy and regenerative medicine applications. The cells have been used in pre-clinical studies to treat a wide range of diseases such as skeletal dysplasia, diaphragmatic hernia and respiratory failure, white matter damage, renal pathologies as well as cancers. Their intermediate state between adult and embryonic stem cells also makes them an ideal candidate for reprogramming to the pluripotent status. PMID: 20739312 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Epigenetic control of Hox genes during neurogenesis, development, and disease. Ann Anat. 2010 Aug 6; Authors: Barber BA, Rastegar M The process of mammalian development is established through multiple complex molecular pathways acting in harmony at the genomic, proteomic, and epigenomic levels. The outcome is profoundly influenced by the role of epigenetics through transcriptional regulation of key developmental genes. Epigenetics refer to changes in gene expression that are inherited through mechanisms other than the underlying DNA sequence, which control cellular morphology and identity. It is currently well accepted that epigenetics play central roles in regulating mammalian development and cellular differentiation by dictating cell fate decisions via regulation of specific genes. Among these genes are the Hox family members, which are master regulators of embryonic development and stem cell differentiation and their mis-regulation leads to human disease and cancer. The Hox gene discovery led to the establishment of a fundamental role for basic genetics in development. Hox genes encode for highly conserved transcription factors from flies to humans that organize the anterior-posterior body axis during embryogenesis. Hox gene expression during development is tightly regulated in a spatiotemporal manner, partly by chromatin structure and epigenetic modifications. Here, we review the impact of different epigenetic mechanisms in development and stem cell differentiation with a clear focus on the regulation of Hox genes. PMID: 20739155 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | [Assessment of gene therapy and regenerative therapy using radionuclide technique] Nippon Hoshasen Gijutsu Gakkai Zasshi. 2010 May 20;66(5):542-6 Authors: Inubushi M PMID: 20628223 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Three-dimensional perfusion bioreactor culture supports differentiation of human fetal liver cells. Tissue Eng Part A. 2010 Jun;16(6):2007-16 Authors: Schmelzer E, Triolo F, Turner ME, Thompson RL, Zeilinger K, Reid LM, Gridelli B, Gerlach JC The ability of human fetal liver cells to survive, expand, and form functional tissue in vitro is of high interest for the development of bioartificial extracorporeal liver support systems, liver cell transplantation therapies, and pharmacologic models. Conventional static two-dimensional culture models seem to be inadequate tools. We focus on dynamic three-dimensional perfusion technologies and developed a scaled-down bioreactor, providing decentralized mass exchange with integral oxygenation. Human fetal liver cells were embedded in a hyaluronan hydrogel within the capillary system to mimic an in vivo matrix and perfusion environment. Metabolic performance was monitored daily, including glucose consumption, lactate dehydrogenase activity, and secretion of alpha-fetoprotein and albumin. At culture termination cells were analyzed for proliferation and liver-specific lineage-dependent cytochrome P450 (CYP3A4/3A7) gene expression. Occurrence of hepatic differentiation in bioreactor cultures was demonstrated by a strong increase in CYP3A4/3A7 gene expression ratio, lower alpha-fetoprotein, and higher albumin secretion than in conventional Petri dish controls. Cells in bioreactors formed three-dimensional structures. Viability of cells was higher in bioreactors than in control cultures. In conclusion, the culture model implementing three-dimensionality, constant perfusion, and integral oxygenation in combination with a hyaluronan hydrogel provides superior conditions for liver cell survival and differentiation compared to conventional culture. PMID: 20088704 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A feasibility of useful cell-based therapy by bone regeneration with deciduous tooth stem cells, dental pulp stem cells, or bone-marrow-derived mesenchymal stem cells for clinical study using tissue engineering technology. Tissue Eng Part A. 2010 Jun;16(6):1891-900 Authors: Yamada Y, Nakamura S, Ito K, Sugito T, Yoshimi R, Nagasaka T, Ueda M This study investigated the effect of bone regeneration with dental pulp stem cells (DPSCs), deciduous tooth stem cells (DTSCs), or bone-marrow-derived mesenchymal stem cells (BMMSCs) for clinical study on hydroxyapatite-coated osseointegrated dental implants, using tissue engineering technology. In vitro, human DPSCs and DTSCs expressed STRO-1, CD13, CD29, CD 44, CD73, and osteogenic marker genes such as alkaline phosphatase, Runx2, and osteocalcin. In vivo, prepared bone defect model was implanted using graft materials as follows: platelet-rich plasma (PRP), PRP and canine BMMSCs (cBMMSCs), PRP and canine DPSCs (cDPSCs), PRP and puppy DTSCs (pDTSCs), and control (defect only). After 8 weeks, the dental implants were installed, and 16 weeks later the sections were evaluated histologically and histometrically. The cBMMSCs/PRP, cDPSCs/PRP, and pDTSCs/PRP groups had well-formed mature bone and neovascularization. Histometrically, the bone-implant contact was significantly different between the cBMMSCs/PRP, cDPSCs/PRP, pDTSCs/PRP groups, and the control and PRP groups (p < 0.01). These results demonstrated that these stem cells with PRP have the ability to form bone, and this bone formation activity might be useful for osseointegrated hydroxyapatite-coated dental implants with good levels of bone-implant contact. PMID: 20067397 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Live celloidosome structures based on the assembly of individual cells by colloid interactions. Phys Chem Chem Phys. 2010 Aug 25; Authors: Fakhrullin RF, Brandy ML, Cayre OJ, Velev OD, Paunov VN A new class of colloid structures, celloidosomes, has been developed which represent hollow microcapsules whose membranes consist of a single monolayer of living cells. Two routes for producing these structures were designed based on templating of: (i) air bubbles and (ii) anisotropic microcrystals of calcium carbonate with living cells, which allowed us to fabricate celloidosomes of spherical, rhombohedral and needle-like morphologies. Air microbubbles were templated by yeast cells coated with poly(allylamine hydrochloride) (PAH), then coated with carboxymethylcellulose and rehydrated resulting in the formation of spherical multicellular structures. Similarly, calcium carbonate microcrystals of anisotropic shapes were coated with several consecutive layers of oppositely charged polyelectrolytes to obtain a positive surface charge which was used to immobilise yeast cells coated with anionic polyelectrolyte of their surfaces. After dissolving of sacrificial cores, hollow multicellular structures were obtained. The viability of the cells in the produced structures was confirmed by using fluorescein diacetate. In order to optimize the separation of celloidosomes from free cells magnetic nanoparticles were immobilised onto the surface of templates prior to the cells deposition, which greatly facilitated the separation using a permanent magnet. Two alternative approaches were developed to form celloidosome structures using magnetically functionalised core-shell microparticles which resulted in the formation of celloidosomes with needle-like and cubic-like geometries which follows the original morphology of the calcium carbonate microcrystals. Our methods for fabrication of celloidosomes may found applications in the development of novel symbiotic bio-structures, artificial multicellular organisms and in tissue engineering. The unusual structure of celloidosomes resembles the primitive forms of multicellular species, like Volvox, and other algae and could be regarded as one possible mechanism of the evolutionary development of multicellularity. PMID: 20737085 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Local antibiotic delivery using tailorable chitosan sponges: the future of infection control? J Orthop Trauma. 2010 Sep;24(9):592-7 Authors: Stinner DJ, Noel SP, Haggard WO, Watson JT, Wenke JC OBJECTIVES:: Local antibiotic delivery is a viable and attractive option for preventing infection. Unfortunately, the current options are limited and often necessitate surgical removal. This study evaluates the ability of a biodegradable and biocompatible chitosan sponge to minimize infection by delivering local antibiotics within the wound. METHODS:: A complex musculoskeletal wound was created on the hindlimb of goats and contaminated with Pseudomonas aeruginosa (lux) or Staphylococcus aureus (lux) bacteria. These bacteria are genetically engineered to emit photons, allowing for quantification with a photon-counting camera system. The wounds were closed and similarly débrided and irrigated with 9 L normal saline using bulb-syringe irrigation 6 hours after inoculation. Goats were assigned to different treatment groups: a control group with no adjunctive treatment and an experimental group using a chitosan sponge loaded with either amikacin (for wounds contaminated with P. aeruginosa) or vancomycin (for wounds contaminated with S. aureus). The wounds were closed after the procedure and evaluated 48 hours after initial contamination. Serum levels of the antibiotics were also measured at 6, 12, 24, 36, and 42 hours after treatment was initiated. RESULTS:: The wounds treated with the antibiotic-loaded chitosan sponge had significantly less bacteria than the untreated wounds (P < 0.05). The highest serum levels were 6 hours after treatment but remained less than 15% of target serum levels for systemic treatment. At study end point, all sponges were between 60% and 100% degraded. CONCLUSIONS:: The chitosan sponges are effective delivering the antibiotic and reducing the bacteria within the wounds. PMID: 20736801 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Potential applications of natural origin polymer-based systems in soft tissue regeneration. Crit Rev Biotechnol. 2010 Sep;30(3):200-21 Authors: Silva SS, Mano JF, Reis RL Despite the many advances in tissue engineering approaches, scientists still face significant challenges in trying to repair and replace soft tissues. Nature-inspired routes involving the creation of polymer-based systems of natural origins constitute an interesting alternative route to produce novel materials. The interest in these materials comes from the possibility of constructing multi-component systems that can be manipulated by composition allowing one to mimic the tissue environment required for the cellular regeneration of soft tissues. For this purpose, factors such as the design, choice, and compatibility of the polymers are considered to be key factors for successful strategies in soft tissue regeneration. More recently, polysaccharide-protein based systems have being increasingly studied and proposed for the treatment of soft tissues. The characteristics, properties, and compatibility of the resulting materials investigated in the last 10 years, as well as commercially available matrices or those currently under investigation are the subject matter of this review. PMID: 20735324 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Mineralization of Hydrogels for Bone Regeneration. Tissue Eng Part B Rev. 2010 Aug 25; Authors: Gkioni C, Leeuwenburgh S, Douglas T, Mikos AG, Jansen J Hydrogels are an important class of highly hydrated polymers that are widely investigated for potential use in soft tissue engineering. Generally, however, hydrogels lack the ability to mineralize, preventing the formation of chemical bonds with hard tissues such as bone. A recent trend in tissue engineering involves the development of hydrogels that possess the capacity to mineralize. The strategy that has attracted most interest has been the incorporation of inorganic phases such as calcium phosphate ceramics and bioglasses into hydrogel matrices. These inorganic particles act as nucleation sites that enable further mineralization, thus improving the mechanical properties of the composite material. A second route to create nucleation sites for calcification of hydrogels involves the use of features from the physiological mineralization process. Examples of these biomimetic mineralization strategies include i) soaking of hydrogels in solutions that are saturated with respect to calcium phosphate, ii) incorporation of enzymes that catalyze deposition of bone mineral and iii) incorporation of synthetic analogues to matrix vesicles that are the initial sites of biomineralization. Functionalization of the polymeric hydrogel backbone with negatively charged groups is a third mechanism to promote mineralization in otherwise inert hydrogels. This review summarizes the main strategies that have been developed in the past decade to calcify hydrogel matrices and render these hydrogels suitable for applications in bone regeneration. PMID: 20735319 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Minimally invasive sinus augmentation. J Oral Implantol. 2010;36(4):295-304 Authors: Steiner GG, Steiner DM, Herbias MP, Steiner R Abstract Sinus lift surgery has become more common as patients choose dental implants for tooth replacement. The recent development of a graft material that stimulates osteogenesis coupled with the application of tissue engineering principles has allowed for refinement of this surgical modality. A simple nontraumatic subantral sinus lift microsurgery is presented. This sinus lift microsurgery resulted in a 97% implant success rate. PMID: 20735266 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The Effects of 17-beta Estradiol on Enhancing Proliferation of Human Bone Marrow Mesenchymal Stromal Cells in vitro. Stem Cells Dev. 2010 Aug 24; Authors: Hong L, Zhang G, Sultana H, Yu Y, Wei Z Human bone marrow mesenchymal stromal cells (MSCs) with self-renewal and multiple differentiation potentials are considered a possible cell source for tissue engineering and regenerative medicine. However, the limited amount of MSCs in bone marrow and the loss of differentiation capacity following in vitro expansion restrict their practical application. Effective improvement of MSC proliferation is necessary for the clinical application of MSCs-based tissue engineering. The effects of estrogen supplements on proliferation and characterizations of human MSCs were investigated at the present study. Supplements of 17-beta estradiol (E2) significantly increase the proliferation of human MSCs in vitro. The dose range of E2 to significantly increase MSC proliferation differs in the gender of MSC donor. E2 supplementation in cell proliferation maintains characterizations of MSCs including cell surface markers, and osteogenic and adipogenic differentiation capacities. These data indicate that estrogen treatment can play an important role in improving human MSCs' expansion in vitro, which will effectively facilitate MSCs' function in the practical application of tissue engineering and regeneration. PMID: 20735179 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Defining the risks of mesenchymal stromal cell therapy. Cytotherapy. 2010 Sep;12(5):576-8 Authors: Prockop DJ, Brenner M, Fibbe WE, Horwitz E, Le Blanc K, Phinney DG, Simmons PJ, Sensebe L, Keating A Abstract We address the issue of the potential for malignant transformation of cultured mesenchymal stromal cells (MSC) commonly used in clinical cell-therapy protocols and describe the culture conditions under which tumorigenesis is likely to be an extremely uncommon event. PMID: 20735162 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Canine adipose-derived-mesenchymal stem cells do not lose stem features after a long-term cryopreservation. Res Vet Sci. 2010 Aug 21; Authors: Martinello T, Bronzini I, Maccatrozzo L, Mollo A, Sampaolesi M, Mascarello F, Decaminada M, Patruno M Adult stem cells are nowadays used for treating several pathologies. A putative stem cell population was found in the adipose tissue of mammals and canine adipose tissue-derived-mesenchymal stem cells (cA-MSC) have been shown to possess the capacity to differentiate into several lineages. The main goal of our research was to fully characterize cA-MSC and examine the effects of cryopreservation on their stemness features. Each sample of cA-MSC was analyzed immediately and then again after being frozen in liquid nitrogen for one year. After the cryopreservation period cells conserved their fibroblast-like morphology, alkaline phosphatase positivity and CD expression but showed a lower proliferation ratio and a lower telomerase activity in comparison with fresh cells. Finally, the cryopreservation protocol did not change the cA-MSC adipogenic, osteogenic and myogenic differentiative potential. Our data demonstrate that stored cA-MSC might represent a promising type of progenitor cell for autologous cellular-based therapies in veterinary medicine. PMID: 20732703 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Stem cells in the treatment of inflammatory arthritis. Best Pract Res Clin Rheumatol. 2010 Aug;24(4):565-574 Authors: Tyndall A, van Laar JM Autologous haematopoietic stem cell transplantation in patients with rheumatoid arthritis (RA) resulted in a positive short-term outcome clinically with low treatment-related toxicity. However, early conditioning regimens were of low immunoablative intensity and most patients relapsed. Mechanistic studies suggest that residual lesional effector cells may have been responsible for the relapses. The introduction of biopharmaceuticals has, for the moment, reduced the need for further experimental studies. Juvenile idiopathic arthritis patients, mostly of the systemic subgroup, have shown nearly 33% durable drug-free remission, but with significant toxicity, including fatal macrophage-activation syndrome early in the programme. Later modifications to the protocol have reduced this toxicity. Mesenchymal stem cells (MSCs), derived from several sources including bone marrow and adipose tissue, are being tested as tissue-regenerative and immunomodulating agents in many autoimmune diseases and animal models of inflammatory arthritis have been positive. MSCs and other stromal cells derived from actively inflamed synovium and peripheral blood of RA patients do not always demonstrate a full range of differentiation potential compared with healthy MSCs, although their immunomodulalatory capacity is unimpaired. PMID: 20732653 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Ageing and neurodegenerative diseases. Ageing Res Rev. 2010 Aug 20; Authors: Hung CW, Chen YC, Hsieh WL, Chiou SH, Kao CL Ageing, which all creatures must encounter, is a challenge to every living organism. In the human body, it is estimated that cell division and metabolism occurs exuberantly until about 25 years of age. Beyond this age, subsidiary products of metabolism and cell damage accumulate, and the phenotypes of ageing appear, causing disease formation. Among these age-related diseases, neurodegenerative diseases have drawn a lot of attention due to their irreversibility, lack of effective treatment, and accompanied social and economical burdens. In seeking to ameliorate ageing and age-related diseases, the search for anti-ageing drugs has been of much interest. Numerous studies have shown that the plant polyphenol, resveratrol (3,5,4'-trihydroxystilbene), extends the lifespan of several species, prevents age-related diseases, and possesses anti-inflammatory, and anti-cancer properties. The beneficial effects of resveratrol are believed to be associated with the activation of a longevity gene, SirT1. In this review, we discuss the pathogenesis of age-related neurodegenerative diseases including Alzheimer's disease, Parkinson's disease and cerebrovascular disease. The therapeutic potential of resveratrol, diet and the roles of stem cell therapy are discussed to provide a better understanding of the ageing mystery. PMID: 20732460 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Heparin-binding-affinity-based delivery systems releasing nerve growth factor enhance sciatic nerve regeneration. J Biomater Sci Polym Ed. 2010;21(6):771-87 Authors: Wood MD, Hunter D, Mackinnon SE, Sakiyama-Elbert SE The controlled delivery of nerve growth factor (NGF) to the peripheral nervous system has been shown to enhance nerve regeneration following injury, although the effect of release rate has not been previously studied with an affinity-based delivery system (DS). The goal of this research was to determine if the binding site affinity of the DS affected nerve regeneration in vivo using nerve guidance conduits (NGCs) in a 13-mm rat sciatic nerve defect. These DSs consisted of bi-domain peptides that varied in heparin-binding affinity, heparin and NGF, which binds to heparin with moderate affinity. Eight experimental groups were evaluated consisting of NGF with DS, control groups excluding one or more components of the DS within silicone conduits and nerve isografts. Nerves were harvested 6 weeks after treatment for analysis by histomorphometry. These DSs with NGF resulted in a higher frequency of nerve regeneration compared to control groups and were similar to the nerve isograft group in measures of nerve fiber density and percent neural tissue, but not in total nerve fiber count. In addition, these DSs with NGF contained a significantly greater percentage of larger diameter nerve fibers, suggesting more mature regenerating nerve content. While there were no differences in nerve regeneration due to varying peptide affinity with these DSs, their use with NGF enhanced peripheral nerve regeneration through a NGC across a critical nerve gap. PMID: 20482984 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | Cytocompatibility of bio-inspired silicon carbide ceramics. J Biomed Mater Res B Appl Biomater. 2010 Aug 24; Authors: López-Ãlvarez M, de Carlos A, González P, Serra J, León B Due to its good mechanical and biochemical properties and, also, because of its unique interconnected porosity, bio-inspired silicon carbide (bioSiC) can be considered as a promising material for biomedical applications, including controlled drug delivery devices and tissue engineering scaffolds. This innovative material is produced by molten-Si infiltration of carbon templates, obtained by controlled pyrolysis of vegetable precursors. The final SiC ceramic presents a porous-interconnected microstructure that mimics the natural hierarchical structure of bone tissue and allows the internal growth of tissue, as well as favors angiogenesis. In the present work, the in vitro cytocompatibility of the bio-inspired SiC ceramics obtained, in this case, from the tree sapelli (Entandrophragma cylindricum) was evaluated. The attachment, spreading, cytoskeleton organization, proliferation, and mineralization of the preosteoblastic cell line MC3T3-E1 were analyzed for up to 28 days of incubation by scanning electron microscopy, interferometric profilometry, confocal laser scanning microscopy, MTT assay, as well as red alizarin staining and quantification. Cells seeded onto these ceramics were able to attach, spread, and proliferate properly with the maintenance of the typical preosteoblastic morphology throughout the time of culture. A certain level of mineralization on the surface of the sapelli-based SiC ceramics is observed. These results demonstrated the cytocompatibility of this porous and hierarchical material. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20737554 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Fabrication of polyvinyl alcohol/gelatin nanofiber composites and evaluation of their material properties. J Biomed Mater Res B Appl Biomater. 2010 Aug 24; Authors: Linh NT, Min YK, Song HY, Lee BT Electrospinning of polyvinyl alcohol (PVA), gelatin (GE), and a PVA/GE blend was conducted with the aim of fabricating biodegradable scaffolds for tissue engineering. The process parameters including the concentration of GE in PVA/GE blends, electrical field, and tip-to-collector distance (TCD) were investigated. Electrospinning processes were conducted at three different GE concentrations (PVA/GE = 2/8, 6/4, and 8/2), and the voltage and TCD were varied from 18 to 24 kV and 7 to 20 cm, respectively. The average diameter of the electrospun PVA, GE, and PVA/GE blend fibers ranged from 50 to 150 nm. The TCD had significant effects on the average diameter of the PVA/GE nanofiber, while changes in the voltage did not significantly affect the diameter of the PVA/GE nanofiber. The miscibility of the PVA/GE blend fibers was examined by differential scanning calorimetry, and X-ray diffraction was used to determine the crystallinity of the membrane. Tensile strength was measured to evaluate the physical properties of the membrane. Based on the combined results of this study, the PVA/GE membrane holds great promise for use in tissue engineering applications, especially in bone or drug delivery systems. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010. PMID: 20737434 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | In Vitro Evaluation of Magnetic Resonance Imaging Contrast Agents for Labeling Human Liver Cells: Implications for Clinical Translation. Mol Imaging Biol. 2010 Aug 25; Authors: Raschzok N, Muecke DA, Adonopoulou MK, Billecke N, Werner W, Kammer NN, Zielinski A, Behringer PA, Ringel F, Huang MD, Neuhaus P, Teichgräber U, Sauer IM PURPOSE: Magnetic resonance imaging (MRI) is a promising approach for non-invasive monitoring after liver cell transplantation. We compared in vitro labeling of human liver cells with nano-sized (SPIO) and micron-sized iron oxide particles (MPIO). PROCEDURES: The cellular iron load was quantified and phantom studies were performed using 3.0-T MRI. Transferrin receptor and ferritin gene expression, reactive oxygen species (ROS) formation, transaminase leakage, and urea synthesis were investigated over 6 days. RESULTS: Incubation with MPIO produced stronger signal extinctions in MRI at similar iron loads within shorter labeling time. MPIO had no negative effects on the cellular iron homeostasis or cell performance, whereas SPIO caused temporary ROS formation and non-physiologic activation of the iron metabolic pathway. CONCLUSIONS: Our findings suggest that MPIO are suited for clinical translation of strategies for cellular imaging with MRI. Attention should be paid to iron release and oxidative stress caused by biodegradable contrast agents. PMID: 20737221 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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