|  |  |  | | | | | TE-RegenMed-StemCell feed | | | | | | | | | | | | | | | | | | | Direct comparison of progenitor cells derived from adipose, muscle, and bone marrow from wild-type or craniosynostotic rabbits. Plast Reconstr Surg. 2011 Jan;127(1):88-97 Authors: Cooper GM, Durham EL, Cray JJ, Bykowski MR, DeCesare GE, Smalley MA, Mooney MP, Campbell PG, Losee JE Reports have identified cells capable of osteogenic differentiation in bone marrow, muscle, and adipose tissues, but there are few direct comparisons of these different cell types. Also, few have investigated the potential connection between a tissue-specific abnormality and cells derived from seemingly unrelated tissues. In this article, the authors compare cells isolated from wild-type rabbits or rabbits with nonsyndromic craniosynostosis, defined as the premature fusion of one or more of the cranial sutures. PMID: 20871482 [PubMed - indexed for MEDLINE] | | | | | | | | | | | | | | | | | | | | | | | | | A simple method to sort ESC-derived adipocytes. Cytometry A. 2010 Oct;77(10):990-5 Authors: Schaedlich K, Knelangen JM, Navarrete Santos A, Fischer B, Navarrete Santos A Because of the increasing incidence of worldwide obesity, cell culture models which enable the study of adipose tissue development are of particular importance. The murine embryonic stem cell (ESC) line CGR8 differentiates into adipocytes with a differentiation efficiency of up to 15%. A critical step for the analysis of stem cell-derived adipogenesis is the reliable separation of adipocytes. Here we report on how to (i) gently separate the cells of embryoid bodies (EBs) and (ii) identify and sort adipocytes from the rest of the heterogeneous cell mixture. Up to the present, no adipocyte specific surface marker is known for fluorescence activated cell sorting (FACS). After separation we employed two independently existing FACS methods for adipocyte cell sorting. These methods are based on Nile red staining and granularity. For stem cell-derived adipocytes only the combination of both methods led to a reliable, efficient, and highly reproducible FACS analysis, as shown by the presence and absence of adipocyte specific markers in positively and negatively sorted cells. © 2010 International Society for Advancement of Cytometry. PMID: 21290474 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Heme oxygenase-1 induction enhances cell survival and restores contractility to unvascularized three-dimensional adult cardiomyocyte grafts implanted <i>in vivo</i> Tissue Eng Part A. 2011 Feb 3; Authors: Kawamoto S, Flynn JP, Shi Q, Sakr SW, Luo J, Allen MD Autologous adult cardiomyocytes are not utilized for heart repair strategies because of their rapid apoptosis after implantation. We examined whether induction of heme oxygenase-1 (HO-1), a mediator of pre-conditioning, could enhance early post-implant myocyte survival. Three-dimensional 5x5mm patches of full-thickness adult murine atrial wall, including cardiomyocytes, capillary networks, and extracellular matrix, were cultured with or without HO-1 inducer cobalt protoporphryin (CoPP), or the HO-1 inhibitor, tin protoporphyrin (SnPP), or both. Patches were then implanted subcutaneously. Freshly procured atrial wall patches implanted without pre-culturing served as additional controls. By 14 days post implant, graft cardiomyocyte content was significantly greater in CoPP-treated patches than in either control group (P <0.02). Adult cardiomyocytes did not contract in culture nor immediately after implantation. However, by 14 days post implant, spontaneous contraction had recovered in 47% of CoPP-treated patches, but in only 6% of pre-cultured patches without CoPP, 0% of SnPP-treated patches, and 0% of uncultured patches (P <0.03). CoPP-treated adult cardiomyocyte patches were also observed to remodel spontaneously into endothelial-lined chambers that pumped non-clotting blood. These findings demonstrate that adult cardiomyocytes have more plasticity and capacity for functional recovery than previously recognized and could have application as an autologous cardiomyocyte source for tissue engineering. PMID: 21288159 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Production of an optimized tissue-engineered pig connective tissue for the reconstruction of the urinary tract. Tissue Eng Part A. 2011 Feb 3; Authors: Ouellet G, Dubé J, Gauvin R, Laterreur V, Bouhout S, Bolduc S Non-urological autologous tissues are used for urethral reconstruction to correct urinary tract disorders but are still leading to complications. Other substitutes have been studied on small animal models without great success. For preclinical tests, we selected the porcine model for its similarity to the human urinary tract. Up to now, porcine skin fibroblasts were not able to synthesize enough extracellular matrix (ECM) under standard conditions to sustain the formation of an adequate tissue for transplantation purposes. Therefore, our goal was to optimize the harvesting site and culture conditions to obtain a thick and easy to handle porcine fibroblast tissue. The oral mucosa was found to be the ideal harvesting site and a culture temperature of 39°C enabled the formation of a good porcine fibroblast sheet. We successfully superimpose three fibroblast sheets that merged into a thick and resistant tissue where physiological ECM was produced. Mechanical resistance evaluation by uniaxial traction on the three-layer fibroblast constructs also demonstrated its suitable properties. The production of this porcine connective tissue offers an interesting option in the field of urological tissue engineering. Autologous experiments on a larger animal model are now possible and accessible, allowing the performance of long-term in vivo studies. PMID: 21288158 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Preparation and properties of nano-hydroxyapatite/PCL-PEG-PCL composite membranes for tissue engineering applications. J Biomed Mater Res B Appl Biomater. 2011 Feb 2; Authors: Fu SZ, Wang XH, Guo G, Shi S, Fan M, Liang H, Luo F, Qian ZY Nano-hydroxyapatite (n-HA)/poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCL-PEG-PCL, PCEC) composite membranes were prepared by solvent casting and evaporation method. The structure and properties of the membranes were investigated by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), water contact angle measurements, in vitro hydrolytic degradation, mechanical test, and cell culture. The effect of n-HA content on physical-chemical properties of the n-HA/PCEC composite membranes was studied. The results showed that the shape and size of micropores of the composite membranes changed with n-HA content increased; the tensile strength decreased with the increase of n-HA content. The osteoblast cell was cultured on the membranes, good cell attachment and growth manner were observed after postseeding for 1 day. MTT assays showed that the n-HA/PCEC membranes had no negative effect on the cell viability and proliferation. These results suggested that the obtained n-HA/PCEC composite membranes in this study might have prospective applications in tissue engineering field. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011. PMID: 21290585 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Relative influence of surface topography and surface chemistry on cell response to bone implant materials. Part 2: biological aspects. Proc Inst Mech Eng H. 2010 Dec;224(12):1487-507 Authors: Anselme K, Ponche A, Bigerelle M A current medical challenge is the replacement of tissue which can be thought of in terms of bone tissue engineering approaches. The key problem in bone tissue engineering lies in associating bone stem cells with material supports or scaffolds that can be implanted in a patient. Beside bone tissue engineering approaches, these types of materials are used daily in orthopaedics and dental practice as permanent or transitory implants such as ceramic bone filling materials or metallic prostheses. Consequently, it is essential to better understand how bone cells interact with materials. For several years, the current authors and others have developed in vitro studies in order to elucidate the mechanisms underlying the response of human bone cells to implant surfaces. This paper reviews the current state of knowledge and proposes future directions for research in this domain. PMID: 21287833 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Mechanisms of fluid-flow-induced matrix production in bone tissue engineering. Proc Inst Mech Eng H. 2010 Dec;224(12):1509-21 Authors: Morris HL, Reed CI, Haycock JW, Reilly GC Matrix production by tissue-engineered bone is enhanced when the growing tissue is subjected to mechanical forces and/or fluid flow in bioreactor culture. Cells deposit collagen and mineral, depending upon the mechanical loading that they receive. However, the molecular mechanisms of flow-induced signal transduction in bone are poorly understood. The hyaluronan (HA) glycocalyx has been proposed as a potential mediator of mechanical forces in bone. Using a parallel-plate flow chamber the effects of removal of HA on flow-induced collagen production and NF-kappaB activation in MLO-A5 osteoid osteocytes were investigated. Short periods of fluid flow significantly increased collagen production and induced translocation of the NF-kappaB subunit p65 to the cell's nuclei in 65 per cent of the cell population. Enzymatic removal of the HA coat and antibody blocking of CD44 (a transmembrane protein that binds to HA) eliminated the fluid-flow-induced increase in collagen production but had no effect on the translocation of p65. HA and CD44 appear to play roles in transducing the flow signals that modulate collagen production over long-term culture but not in the short-term flow-induced activation of NF-kappaB, implying that multiple signalling events are initiated from the commencement of flow. Understanding the mechanotransduction events that enable fluid flow to stimulate bone matrix production will allow the optimization of bioreactor design and flow profiles for bone tissue engineering. PMID: 21287834 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Osteoblasts in bone tissue engineering. Proc Inst Mech Eng H. 2010 Dec;224(12):1415-40 Authors: Jayakumar P, Di Silvio L Osteoblasts are integral to the development, growth, function, repair and maintenance of bone. The osteoblast forms organic, non-mineralized bone matrix and is involved in complex interactions with a variety of factors, mediators and cell types. Degeneration, pathology, and trauma cause disruption and destruction of the normal skeletal environment and may lead to bone loss. There is a rise in active populations involved in trauma, elderly patients with fragility fractures and an overall increase in primary, revision and reconstructive bone and joint surgery. Despite the rapid evolution of implant technologies and bone grafting techniques, there is still a great demand for novel bone replacement strategies. Bone tissue engineering is the state of the art science with the potential to regenerate bone with natural form and function. This review presents the biology of osteoblasts and their current applications in bone tissue engineering biotechnologies and role in stem cell, bioactive factor, recombinant signalling molecule and gene therapy research. PMID: 21287829 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Integration of cellulases into bacterial cellulose: Toward bioabsorbable cellulose composites. J Biomed Mater Res B Appl Biomater. 2011 Feb 2; Authors: Hu Y, Catchmark JM Cellulose biodegradation resulting from enzymolysis generally occurs in nature rather than in the human body because of the absence of cellulose degrading enzymes. In order to achieve in-vivo degradation in human body for in-vivo tissue regeneration applications, we developed a bioaborbable bacterial cellulose (BBC) material, which integrates one or more cellulose degrading enzymes (cellulases), and demonstrated its degradability in vitro using buffers with pH values relevant to wound environments. We introduced a double lyophilizing process to retain the microstructure of the bacterial cellulose as well as the activity of embedded enzymes allowing for long-term storage of the material, which only requires hydration before use. Enzymes and their combinations have been examined to optimize the in-vitro degradation of the BBC material. In-vitro studies revealed that acidic cellulases from Trichoderma viride showed reasonable activity for pH values ranging from 4.5 to 6.0. A commercial cellulase (cellulase-5000) did not show good activity at pH 7.4, but its degrading ability increased when used in conjunction with a β-glucosidase from Bacillus subtilis or a β-glucosidase from Trichoderma sp. Given the harmless glucose product of the enzymatic degradation of cellulose, the BBC material may be ideal for many wound care and tissue engineering applications for the bioabsorbable purpose. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011. PMID: 21290589 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Bacterial cellulose as a potential vascular graft: Mechanical characterization and constitutive model development. J Biomed Mater Res B Appl Biomater. 2011 Feb 2; Authors: Zahedmanesh H, Mackle JN, Sellborn A, Drotz K, Bodin A, Gatenholm P, Lally C Bacterial cellulose (BC) is a polysaccharide produced by Acetobacter Xylinum bacteria with interesting properties for arterial grafting and vascular tissue engineering including high-burst pressure, high-water content, high crystallinity, and an ultrafine highly pure fibrous structure similar to that of collagen. Given that compliance mismatch is one of the main factors contributing to the development of intimal hyperplasia in vascular replacement conduits, an in depth investigation of support mechanical properties of BC is required to further supporting its use in cardiovascular-grafting applications. The aim of this study was to mechanically characterize BC and also study its potential to accommodate vascular cells. To achieve these aims, inflation tests and uniaxial tensile tests were carried out on BC samples. In addition, dynamic compliance tests were conducted on BC tubes, and the results were compared to that of arteries, saphenous vein, expanded polytetrafluoroethylene, and Dacron grafts. BC tubes exhibited a compliance response similar to human saphenous vein with a mean compliance value of 4.27 × 10(-2) % per millimeter of mercury over the pressure range of 30-120 mmHg. In addition, bovine smooth muscle cells and endothelial cells were cultured on BC samples, and histology and fluorescent imaging analysis were carried out showing good adherence and biocompatibility. Finally, a method to predict the mechanical behavior of BC grafts in situ was established, whereby a constitutive model for BC was determined and used to model the BC tubes under inflation using finite element analysis. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011. PMID: 21290588 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Focal adhesions in osteoneogenesis. Proc Inst Mech Eng H. 2010 Dec;224(12):1441-53 Authors: Biggs MJ, Dalby MJ As materials technology and the field of tissue engineering advance, the role of cellular adhesive mechanisms, in particular, interactions with implantable devices, becomes more relevant in both research and clinical practice. A key tenet of medical device technology is to use the exquisite ability of biological systems to respond to the material surface or chemical stimuli in order to help to develop next-generation biomaterials. The focus of this review is on recent studies and developments concerning focal adhesion formation in osteoneogenesis, with an emphasis on the influence of synthetic constructs on integrin-mediated cellular adhesion and function. PMID: 21287830 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Polyurethane/fluor-hydroxyapatite nanocomposite scaffolds for bone tissue engineering. Part I: morphological, physical, and mechanical characterization. Int J Nanomedicine. 2011;6:93-100 Authors: Asefnejad A, Behnamghader A, Khorasani MT, Farsadzadeh B In this study, new nano-fluor-hydroxyapatite (nFHA)/polyurethane composite scaffolds were fabricated for potential use in bone tissue engineering. Polyester urethane samples were synthesized from polycaprolactone, hexamethylene diisocyanate, and 1,4-butanediol as chain extender. Nano fluor-hydroxyapatite (nFHA) was successfully synthesized by sol-gel method. The solid-liquid phase separation and solvent sublimation methods were used for preparation of the porous composites. Mechanical properties, chemical structure, and morphological characteristics of the samples were investigated by compressive test, Fourier transform infrared, and scanning electron microscopy (SEM) techniques, respectively. The effect of nFHA powder content on porosity and pore morphology was investigated. SEM images demonstrated that the scaffolds were constituted of interconnected and homogeneously distributed pores. The pore size of the scaffolds was in the range 50-250 μm. The result obtained in this research revealed that the porosity and pore average size decreased and compressive modulus increased with nFHA percentage. Considering morphological, physical, and mechanical properties, the scaffold with a higher ratio of nFHA has suitable potential use in tissue regeneration. PMID: 21289986 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Platelet-derived growth factor applications in periodontal and peri-implant bone regeneration. Expert Opin Biol Ther. 2011 Feb 3; Authors: Kaigler D, Avila G, Wisner-Lynch L, Nevins ML, Nevins M, Rasperini G, Lynch SE, Giannobile WV Introduction: Achieving successful tissue regeneration following traditional therapeutic protocols, combining bone grafts and barrier membranes, may be challenging in certain clinical scenarios. A deeper understanding of periodontal and peri-implant wound healing and recent advances in the field of tissue engineering have provided clinicians with novel means to obtain predictable clinical outcomes. The use of growth factors such as recombinant human platelet-derived growth factor-BB (rhPDGF) with biocompatible matrices to promote tissue regeneration represents a promising approach in the disciplines of periodontology and implantology. Areas covered: This review covers the basic principles of bone and periodontal regeneration, and provides an overview of the biology of PDGF and its potential to predictably and reproducibly promote bone regeneration in regular clinical practice. The results of preclinical and clinical human studies evaluating the effectiveness of growth-factor-enhanced matrices are analyzed and discussed. Expert opinion: Current available evidence supports the use of rhPDGF-enhanced matrices to promote periodontal and peri-implant bone regeneration. PMID: 21288185 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Optically Transparent Recombinant Silk-Elastinlike Protein Polymer Films. J Phys Chem B. 2011 Feb 1; Authors: Teng W, Huang Y, Cappello J, Wu X Recombinant protein polymers, evaluated exten-sively as biomaterials for applications in drug delivery and tissue engineering, are rarely reported as being optically transparent. Here we report the notable optical transparency of films composed of a genetically engineered silk-elastinlike protein polymer SELP-47K. SELP-47K films of 100 μm in thickness display a transmittance of 93% in the wavelength range of 350-800 nm. While covalent cross-linking of SELP-47K via glutaraldehyde decreases its transmittance to 77% at the wavelength of 800 nm, noncovalent cross-linking using methanol slightly increases it to 95%. Non- and covalent cross-linking of SELP-47K films also influences their secondary structures and water contents. Cell viability and proliferation analyses further reveal the excellent cytocompatibility of both non- and covalently cross-linked SELP-47K films. The combination of high optical transparency and cytocompatibility of SELP-47K films, together with their previously reported outstanding mechanical properties, suggests that this protein polymer may be useful in unique, new biomedical applications. PMID: 21288001 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Skeletal stem cells and bone regeneration: translational strategies from bench to clinic. Proc Inst Mech Eng H. 2010 Dec;224(12):1455-70 Authors: Tare RS, Kanczler J, Aarvold A, Jones AM, Dunlop DG, Oreffo RO Clinical imperatives for new bone to replace or restore the function of traumatized or bone lost as a consequence of age or disease has led to the need for therapies or procedures to generate bone for skeletal applications. Tissue regeneration promises to deliver specifiable replacement tissues and the prospect of efficacious alternative therapies for orthopaedic applications such as non-union fractures, healing of critical sized segmental defects and regeneration of articular cartilage in degenerative joint diseases. In this paper we review the current understanding of the continuum of cell development from skeletal stem cells, osteoprogenitors through to mature osteoblasts and the role of the matrix microenvironment, vasculature and factors that control their fate and plasticity in skeletal regeneration. Critically, this review addresses in vitro and in vivo models to investigate laboratory and clinical based strategies for the development of new technologies for skeletal repair and the key translational points to clinical success. The application of developmental paradigms of musculoskeletal tissue formation specifically, understanding developmental biology of bone formation particularly in the adult context of injury and disease will, we propose, offer new insights into skeletal cell biology and tissue regeneration allowing for the critical integration of stem cell science, tissue engineering and clinical applications. Such interdisciplinary, iterative approaches will be critical in taking patient aspirations to clinical reality. PMID: 21287831 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | TGF-{beta}1 induced PI3K/Akt/NF-KB/MMP9 signaling pathway is activated in Philadelphia chromosome-positive Chronic Myeloid Leukemia hemangioblasts. J Biochem. 2011 Feb 1; Authors: Zhu X, Wang L, Zhang B, Li J, Dou X, Zhao RC Overwhelming evidence from Chronic Myeloid Leukemia (CML) research indicates that patients harbor quiescent CML stem cells that are responsible for blast crisis. While the hematopoietic stem cell (HSC) origin of CML was first suggested over 30 years ago, recently CML-initiating cells beyond HSCs are also being investigated. We have previously isolated fetal liver kinase-1-positive (Flk1(+)) cells carrying the BCR/ABL fusion gene from the bone marrow of Philadelphia chromosome-positive (Ph(+)) patients with hemangioblast property. Here we show these cells behave abnormally comparing with the hemangioblasts in healthy donors. These Ph(+) putative CML hemangioblast upregulated TGF-β1 and result in activating matrix metalloproteinase-9 (MMP-9) to enhance s-KitL and s-ICAM-1 secretion. Further studies showed that phosphatidylinositol-3 kinase (PI3K)/Akt/ nuclear factor (NF)-kB signaling pathway was involved in CML pathogenesis. These findings provide direct evidence for the first time that hemangioblasts beyond HSCs play a critical role in the progression of CML. PMID: 21288887 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Bioreactors for bone tissue engineering. Proc Inst Mech Eng H. 2010 Dec;224(12):1523-32 Authors: El Haj AJ, Cartmell SH Engineering bone tissue for use in orthopaedics poses multiple challenges. Providing the appropriate growth environment that will allow complex tissues such as bone to grow is one of these challenges. There are multiple design factors that must be considered in order to generate a functional tissue in vitro for replacement surgery in the clinic. Complex bioreactors have been designed that allow different stress regimes such as compressive, shear, and rotational forces to be applied to three-dimensional (3D) engineered constructs. This review addresses these considerations and outlines the types of bioreactor that have been developed and are currently in use. PMID: 21287835 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Readily available tissue-engineered vascular grafts. Sci Transl Med. 2011 Feb 2;3(68):68ra9 Authors: Dahl SL, Kypson AP, Lawson JH, Blum JL, Strader JT, Li Y, Manson RJ, Tente WE, Dibernardo L, Hensley MT, Carter R, Williams TP, Prichard HL, Dey MS, Begelman KG, Niklason LE Autologous or synthetic vascular grafts are used routinely for providing access in hemodialysis or for arterial bypass in patients with cardiovascular disease. However, some patients either lack suitable autologous tissue or cannot receive synthetic grafts. Such patients could benefit from a vascular graft produced by tissue engineering. Here, we engineer vascular grafts using human allogeneic or canine smooth muscle cells grown on a tubular polyglycolic acid scaffold. Cellular material was removed with detergents to render the grafts nonimmunogenic. Mechanical properties of the human vascular grafts were similar to native human blood vessels, and the grafts could withstand long-term storage at 4°C. Human engineered grafts were tested in a baboon model of arteriovenous access for hemodialysis. Canine grafts were tested in a dog model of peripheral and coronary artery bypass. Grafts demonstrated excellent patency and resisted dilatation, calcification, and intimal hyperplasia. Such tissue-engineered vascular grafts may provide a readily available option for patients without suitable autologous tissue or for those who are not candidates for synthetic grafts. PMID: 21289273 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | In vitro models for bone mechanobiology: applications in bone regeneration and tissue engineering. Proc Inst Mech Eng H. 2010 Dec;224(12):1533-41 Authors: Thompson MS, Epari DR, Bieler F, Duda GN Healthy bone healing is a remarkable, mechanically sensitive, scar-free process that leads rapidly to repair tissue of high mechanical quality and functionality, and knowledge of this process is essential for driving advances in bone tissue engineering and regeneration. Gaining this knowledge requires the use of models to probe and understand the detailed mechanisms of healing, and the tight coupling of biology and mechanics make it essential that both of these aspects are controlled and analysed together, using a mechanobiological approach. This article reviews the literature on in vitro models used for this purpose, beginning with two-dimensional (2D) cell culture models used for applying controlled mechanical stimuli to relevant cells, and detailing the analysis techniques required for understanding both substrate strain and fluid flow stimuli in sufficient detail to relate them to biological response. The additional complexity of three-dimensional (3D) models, enabling more faithful representation of the healing situation, can require correspondingly more sophisticated tools for mechanical and biological analysis, but has recently uncovered exciting evidence for the mechanical sensitivity of angiogenesis, essential for successful healing. Studies using explanted tissue continue to be vital in informing these approaches, providing additional evidence for the relevance of effects in biological and mechanical environments close to those in the living organism. Mechanobiology is essential for the proper analysis of models for bone regeneration, and has an exciting integrative role to play not only in advancing knowledge in this area, but also in ensuring successful translation of new tissue engineering and regenerative therapies to the clinic. PMID: 21287836 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | The influence of the scaffold design on the distribution of adhering cells after perfusion cell seeding. Biomaterials. 2011 Jan 31; Authors: Melchels FP, Tonnarelli B, Olivares AL, Martin I, Lacroix D, Feijen J, Wendt DJ, Grijpma DW In natural tissues, the extracellular matrix composition, cell density and physiological properties are often non-homogeneous. Here we describe a model system, in which the distribution of cells throughout tissue engineering scaffolds after perfusion seeding can be influenced by the pore architecture of the scaffold. Two scaffold types, both with gyroid pore architectures, were designed and built by stereolithography: one with isotropic pore size (412 ± 13 μm) and porosity (62 ± 1%), and another with a gradient in pore size (250-500 μm) and porosity (35%-85%). Computational fluid flow modelling showed a uniform distribution of flow velocities and wall shear rates (15-24 s(-1)) for the isotropic architecture, and a gradient in the distribution of flow velocities and wall shear rates (12-38 s(-1)) for the other architecture. The distribution of cells throughout perfusion-seeded scaffolds was visualised by confocal microscopy. The highest densities of cells correlated with regions of the scaffolds where the pores were larger, and the fluid velocities and wall shear rates were the highest. Under the applied perfusion conditions, cell deposition is mainly determined by local wall shear stress, which, in turn, is strongly influenced by the architecture of the pore network of the scaffold. PMID: 21288567 [PubMed - as supplied by publisher] | | | | | | | | | | | | | | | | | | | | | | | | | Relative influence of surface topography and surface chemistry on cell response to bone implant materials. Part 1: physico-chemical effects. Proc Inst Mech Eng H. 2010 Dec;224(12):1471-86 Authors: Ponche A, Bigerelle M, Anselme K Knowledge of the complexity of cell-material interactions is essential for the future of biomaterials and tissue engineering, but we are still far from achieving a clear understanding, as illustrated in this review. Many factors of the cellular or the material aspect influence these interactions and must be controlled systematically during experiments. On the material side, it is essential to illustrate surface topography by parameters describing the roughness amplitude as well as the roughness organization, and at the scales pertinent for the cell response, i.e., from the nano-scale to the micro-scale. Authors interested in this field must be careful to develop surfaces or methods systematically, allowing perfect control of the relative influences of surface topography and surface chemistry. PMID: 21287832 [PubMed - in process] | | | | | | | | | | | | | | | | | | | | | | | | | Porous hydroxyapatite and gelatin/hydroxyapatite microspheres obtained by calcium phosphate cement emulsion. J Biomed Mater Res B Appl Biomater. 2011 Feb 2; Authors: Perez RA, Del Valle S, Altankov G, Ginebra MP Hydroxyapatite and hybrid gelatine/hydroxyapatite microspheres were obtained through a water in oil emulsion of a calcium phosphate cement (CPC). The setting reaction of the CPC, in this case the hydrolysis of α-tricalcium phosphate, was responsible for the consolidation of the microspheres. After the setting reaction, the microspheres consisted of an entangled network of hydroxyapatite crystals, with a high porosity and pore sizes ranging between 0.5 and 5 μm. The size of the microspheres was tailored by controlling the viscosity of the hydrophobic phase, the rotation speed, and the initial powder size of the CPC. The incorporation of gelatin increased the sphericity of the microspheres, as well as their size and size dispersion. To assess the feasibility of using the microspheres as cell microcarriers, Saos-2 cells were cultured on the microspheres. Fluorescent staining, SEM studies, and LDH quantification showed that the microspheres were able to sustain cell growth. Cell adhesion and proliferation was significantly improved in the hybrid gelatin/hydroxyapatite microspheres as compared to the hydroxyapatite ones. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011. PMID: 21290594 [PubMed - as supplied by publisher] | | | | | | | | | |  | |  | |  |
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