Showing papers on "Tissue engineering published in 2008"
TL;DR: A major focus of this review is on factors that modulate the interaction of macrophages and foreign body giant cells on synthetic surfaces where the chemical, physical, and morphological characteristics of the synthetic surface are considered to play a role in modulating cellular events.
4,053 citations
TL;DR: It is shown that, in the vast majority of circumstances, the sole requirement for biocompatibility in a medical device intended for long-term contact with the tissues of the human body is that the material shall do no harm to those tissues, achieved through chemical and biological inertness.
2,219 citations
TL;DR: This review focuses on the various types of chitosan derivatives and their use in various tissue engineering applications namely, skin, bone, cartilage, liver, nerve and blood vessel.
1,278 citations
TL;DR: Important considerations for designing biodegradable hydrogels for cell encapsulation are described and recent advances in material design and their applications in tissue engineering are highlighted.
Abstract: Encapsulating cells in biodegradable hydrogels offers numerous attractive features for tissue engineering, including ease of handling, a highly hydrated tissue-like environment for cell and tissue growth, and the ability to form in vivo. Many properties important to the design of a hydrogel scaffold, such as swelling, mechanical properties, degradation, and diffusion, are closely linked to the crosslinked structure of the hydrogel, which is controlled through a variety of different processing conditions. Degradation may be tuned by incorporating hydrolytically or enzymatically labile segments into the hydrogel or by using natural biopolymers that are susceptible to enzymatic degradation. Because cells are present during the gelation process, the number of suitable chemistries and formulations are limited. In this review, we describe important considerations for designing biodegradable hydrogels for cell encapsulation and highlight recent advances in material design and their applications in tissue engineering.
1,179 citations
TL;DR: Current biomimetic materials approaches in tissue engineering include synthesis to achieve certain compositions or properties similar to those of the extracellular matrix, novel processing technologies to achieve structural features mimicking the ext racellular matrix on various levels, and biologic delivery strategies to recapitulate a signaling cascade or developmental/wound healing program.
1,169 citations
TL;DR: It is likely that nanofabrication will underpin many technologies in the 21st century and the combination of supramolecular chemistry, materials science, and biomedicine allows application-based materials to be developed.
Abstract: It is likely that nanofabrication will underpin many technologies in the 21st century. Synthetic chemistry is a powerful approach to generate molecular structures that are capable of assembling into functional nanoscale architectures. There has been intense interest in self-assembling low-molecular-weight gelators, which has led to a general understanding of gelation based on the self-assembly of molecular-scale building blocks in terms of non-covalent interactions and packing parameters. The gelator molecules generate hierarchical, supramolecular structures that are macroscopically expressed in gel formation. Molecular modification can therefore control nanoscale assembly, a process that ultimately endows specific material function. The combination of supramolecular chemistry, materials science, and biomedicine allows application-based materials to be developed. Regenerative medicine and tissue engineering using molecular gels as nanostructured scaffolds for the regrowth of nerve cells has been demonstrated in vivo, and the prospect of using self-assembled fibers as one-dimensional conductors in gel materials has captured much interest in the field of nanoelectronics.
1,117 citations
TL;DR: PCL/gelatin 70:30 nanofiber was found to exhibit the most balanced properties to meet all the required specifications for nerve tissue and was used for in vitro culture of nerve stem cells and proved to be a promising biomaterial suitable for nerve regeneration.
1,010 citations
TL;DR: Methods for the isolation, expansion and differentiation of ASCs are presented and described in detail and can be applied to adipose tissues from other species with minimal modifications.
965 citations
TL;DR: Stem cell self-renewal and differentiation is influenced by the 3D environment within the stem cell niche, and the intimate dynamic relationship between cells and the ECM must be understood to ensure appropriate cell behavior.
Abstract: The extracellular matrix (ECM) regulates cell behavior by influencing cell proliferation, survival, shape, migration and differentiation. Far from being a static structure, the ECM is constantly undergoing remodeling--i.e. assembly and degradation--particularly during the normal processes of development, differentiation and wound repair. When misregulated, this can contribute to disease. ECM assembly is regulated by the 3D environment and the cellular tension that is transmitted through integrins. Degradation is controlled by complex proteolytic cascades, and misregulation of these results in ECM damage that is a common component of many diseases. Tissue engineering strives to replace damaged tissues with stem cells seeded on synthetic structures designed to mimic the ECM and thus restore the normal control of cell function. Stem cell self-renewal and differentiation is influenced by the 3D environment within the stem cell niche. For tissue-engineering strategies to be successful, the intimate dynamic relationship between cells and the ECM must be understood to ensure appropriate cell behavior.
939 citations
TL;DR: The role of angiogenic and osteogenic factors in the adaptive response and interaction of osteoblasts and endothelial cells during the multi step process of bone development and repair will be highlighted in this review, with consideration of how some of these key mechanisms can be combined with new developments in tissue engineering to enable repair and growth of skeletal fractures.
Abstract: The repair of large bone defects remains a major clinical orthopaedic challenge. Bone is a highly vascularised tissue reliant on the close spatial and temporal connection between blood vessels and bone cells to maintain skeletal integrity. Angiogenesis thus plays a pivotal role in skeletal development and bone fracture repair. Current procedures to repair bone defects and to provide structural and mechanical support include the use of grafts (autologous, allogeneic) or implants (polymeric or metallic). These approaches face significant limitations due to insufficient supply, potential disease transmission, rejection, cost and the inability to integrate with the surrounding host tissue. The engineering of bone tissue offers new therapeutic strategies to aid musculoskeletal healing. Various scaffold constructs have been employed in the development of tissue-engineered bone; however, an active blood vessel network is an essential pre-requisite for these to survive and integrate with existing host tissue. Combination therapies of stem cells and polymeric growth factor release scaffolds tailored to promote angiogenesis and osteogenesis are under evaluation and development actively to stimulate bone regeneration. An understanding of the cellular and molecular interactions of blood vessels and bone cells will enhance and aid the successful development of future vascularised bone scaffold constructs, enabling survival and integration of bioengineered bone with the host tissue. The role of angiogenic and osteogenic factors in the adaptive response and interaction of osteoblasts and endothelial cells during the multi step process of bone development and repair will be highlighted in this review, with consideration of how some of these key mechanisms can be combined with new developments in tissue engineering to enable repair and growth of skeletal fractures. Elucidation of the processes of angiogenesis, osteogenesis and tissue engineering strategies offer exciting future therapeutic opportunities for skeletal repair and regeneration in orthopaedics.
913 citations
TL;DR: Fibrin is a versatile biopolymer, which shows a great potential in tissue regeneration and wound healing, and is summary the latest developments in organ and tissue regeneration using fibrin as the scaffold material.
Abstract: Tissue engineering combines cell and molecular biology with materials and mechanical engineering to replace damaged or diseased organs and tissues. Fibrin is a critical blood component responsible for hemostasis, which has been used extensively as a biopolymer scaffold in tissue engineering. In this review we summarize the latest developments in organ and tissue regeneration using fibrin as the scaffold material. Commercially available fibrinogen and thrombin are combined to form a fibrin hydrogel. The incorporation of bioactive peptides and growth factors via a heparin-binding delivery system improves the functionality of fibrin as a scaffold. New technologies such as inkjet printing and magnetically influenced self-assembly can alter the geometry of the fibrin structure into appropriate and predictable forms. Fibrin can be prepared from autologous plasma, and is available as glue or as engineered microbeads. Fibrin alone or in combination with other materials has been used as a biological scaffold for s...
01 Jan 2008
TL;DR: This chapter discusses Collagen and the Mechanical Properties of Bone and Calcified Cartilage, as well as biomimetic Collagen Tissues: Collagenous Tissue Engineering and Other Applications.
Abstract: Collagen: Structure and Mechanics, an Introduction.- Collagen Diversity, Synthesis and Assembly.- Collagen Fibrillar Structure and Hierarchies.- Restraining Cross-Links Responsible for the Mechanical Properties of Collagen Fibers: Natural and Artificial.- Damage and Fatigue.- Viscoelasticity, Energy Storage and Transmission and Dissipation by Extracellular Matrices in Vertebrates.- Nanoscale Deformation Mechanisms in Collagen.- Hierarchical Nanomechanics of Collagen Fibrils: Atomistic and Molecular Modeling.- Mechanical Adaptation and Tissue Remodeling.- Tendons and Ligaments: Structure, Mechanical Behavior and Biological Function.- Collagen in Arterial Walls: Biomechanical Aspects.- The Extracellular Matrix of Skeletal and Cardiac Muscle.- The Cornea and Sclera.- Collagen and the Mechanical Properties of Bone and Calcified Cartilage.- Dentin.- Genetic Collagen Diseases: Influence of Collagen Mutations on Structure and Mechanical Behavior.- Biomimetic Collagen Tissues: Collagenous Tissue Engineering and Other Applications.
TL;DR: The goal of investigators working on cartilage regeneration is to develop a system that promotes the production of cartilage tissue that mimics native tissue properties, accelerates restoration of tissue function, and is clinically translatable.
TL;DR: Collagen type I, with selective removal of its telopeptides, has been shown to have many advantageous features for both of these approaches to tissue engineering for regeneration of tissues and organs.
Abstract: There are two major approaches to tissue engineering for regeneration of tissues and organs. One involves cell-free materials and/or factors and one involves delivering cells to contribute to the regeneraion process. Of the many scaffold materials being investigated, collagen type I, with selective removal of its telopeptides, has been shown to have many advantageous features for both of these approaches. Highly porous collagen lattice sponges have been used to support in vitro growth of many types of tissues. Use of bioreactors to control in vitro perfusion of medium and to apply hydrostatic fluid pressure has been shown to enhance histogenesis in collagen scaffolds. Collagen sponges have also been developed to contain differentiating-inducing materials like demineralized bone to stimulate differentiation of cartilage tissue both in vitro and in vivo.
TL;DR: The amniotic membrane (AM) is considered an important potential source for scaffolding material and is composed of a single epithelial layer, a thick basement membrane and an avascular stroma, which creates an almost native scaffold for cell seeding in TE.
Abstract: An important component of tissue engineering (TE) is the supporting matrix upon which cells and tissues grow, also known as the scaffold. Scaffolds must easily integrate with host tissue and provide an excellent environment for cell growth and differentiation. Most scaffold materials are naturally derived from mammalian tissues. The amniotic membrane (AM) is considered an important potential source for scaffolding material. The AM represents the innermost layer of the placenta and is composed of a single epithelial layer, a thick basement membrane and an avascular stroma. The special structure and biological viability of the AM allows it to be an ideal candidate for creating scaffolds used in TE. Epithelial cells derived from the AM have the advantages of stem cells, yet are a more suitable source of cells for TE than stem cells. The extracellular matrix components of the basement membrane of the AM create an almost native scaffold for cell seeding in TE. In addition, the AM has other biological properties important for TE, including anti-inflammatory, anti-microbial, anti-fibrosis, anti-scarring, as well as reasonable mechanical property and low immunogenicity. In this review, the various properties of the AM are discussed in light of their potential use for TE.
TL;DR: Evaluated morphologic characteristics of the tissue formed when SHED seeded in biodegradable scaffolds prepared within human tooth slices are transplanted into immunodeficient mice suggested that the resulting tissue presented architecture and cellularity that closely resemble those of a physiologic dental pulp.
TL;DR: The complex scenario of collagen characteristics, types, fibril arrangement, and collagen structure-related functions (in a variety of connective tissues including bone, cartilage, tendon, skin and cornea) are addressed in this review.
Abstract: Scientific investigations involving collagen have inspired tissue engineering and design of biomaterials since collagen fibrils and their networks primarily regulate and define most tissues The collagen networks form a highly organized, three-dimensional architecture to entrap other ingredients Biomaterials are expected to function as cell scaffolds to replace native collagen-based extracellular matrix The composition and properties of biomaterials used as scaffold for tissue engineering significantly affect the regeneration of neo-tissues and influence the conditions of collagen engineering The complex scenario of collagen characteristics, types, fibril arrangement, and collagen structure-related functions (in a variety of connective tissues including bone, cartilage, tendon, skin and cornea) are addressed in this review Discussion will focus on nanofibrillar assemblies and artificial synthetic peptides that mimic either the fibrillar structure or the elemental components of type I collagen as illustrated by their preliminary applications in tissue engineering Conventional biomaterials used as scaffolds in engineering collagen-containing tissues are also discussed The design of novel biomaterials and application of conventional biomaterials will facilitate development of additional novel tissue engineering bioproducts by refining the currently available techniques The field of tissue engineering will ultimately be advanced by increasing control of collagen in native tissue and by continual manipulation of biomaterials
TL;DR: The results show that unidirectionally oriented nan ofibers significantly induced muscle cell alignment and myotube formation as compared to randomly oriented nanofibers, suggesting that aligned composite nanofiber scaffolds seeded with skeletal muscle cells may provide implantable functional muscle tissues for patients with large muscle defects.
28 May 2008
TL;DR: Compression of Digital Biomedical Signals, Cell-Material Interaction, and Repair and Regeneration of Peripheral Nerves: Historical Perspective.
Abstract: Antimineralization Treatment. Artificial Neural Networks: An Overview. Bioactive Materials and Scaffolds for Tissue Engineering. Biomaterials, Immune Response. Bioresorbable Polymers, An Overview. Cell-Material Interaction. Compression of Digital Biomedical Signals. Electromyography. Magnetic Resonance Microscopy. Melt Spinning. Polyamides (Synthetic and Natural). Repair and Regeneration of Peripheral Nerves: Historical Perspective. Sterilization of Biomedical Materials. Supercritical Fluid Processing. Ultrasonic Therapy, Bone Healing. Wear Debris, Bone Resorption Animal Models. Zirconia Ceramics.
TL;DR: Human bone marrow-derived mesenchymal stem cells (hMSCs) are perivascular cell precursors and may serve as an attractive source of cells for use in vascular tissue engineering and for the study of periv vascular cell differentiation.
TL;DR: Compared to covalent immobilization and physical adsorption, blended electrospinning of laminin and synthetic polymer is a facile and efficient method to modify nanofibers for the fabrication of a biomimetic scaffold.
TL;DR: The matching of physical characteristics to those of the heart, the ability to fine tune degradation rates in biologically relevant media and initial data showing biocompatibility indicate that this material has promise for cardiac tissue engineering applications.
TL;DR: This review focuses on the developments in custom scaffold design and manufacture, highlighting laser sintering, supercritical carbon dioxide processing, growth factor incorporation and zoning, plasma modification of scaffold surfaces, and novel multi‐use temperature‐sensitive injectable materials.
Abstract: Tissue engineering scaffolds are designed to influence the physical, chemical and biological environment surrounding a cell population. In this review we focus on our own work and introduce a range of strategies and materials used for tissue engineering, including the sources of cells suitable for tissue engineering: embryonic stem cells, bone marrow-derived mesenchymal stem cells and cord-derived mesenchymal stem cells. Furthermore, we emphasize the developments in custom scaffold design and manufacture, highlighting laser sintering, supercritical carbon dioxide processing, growth factor incorporation and zoning, plasma modification of scaffold surfaces, and novel multi-use temperature-sensitive injectable materials.
TL;DR: It is shown that the local growth rate of tissue formed by osteoblasts is strongly influenced by the geometrical features of channels in an artificial three-dimensional matrix, implying that cells within the tissue surface are able to sense and react to radii of curvature much larger than the size of the cells themselves.
Abstract: Tissue formation is determined by uncountable biochemical signals between cells; in addition, physical parameters have been shown to exhibit significant effects on the level of the single cell. Beyond the cell, however, there is still no quantitative understanding of how geometry affects tissue growth, which is of much significance for bone healing and tissue engineering. In this paper, it is shown that the local growth rate of tissue formed by osteoblasts is strongly influenced by the geometrical features of channels in an artificial three-dimensional matrix. Curvature-driven effects and mechanical forces within the tissue may explain the growth patterns as demonstrated by numerical simulation and confocal laser scanning microscopy. This implies that cells within the tissue surface are able to sense and react to radii of curvature much larger than the size of the cells themselves. This has important implications towards the understanding of bone remodelling and defect healing as well as towards scaffold design in bone tissue engineering.
TL;DR: The combination of natural proteins and synthetic polymers to create electrospun fibrous structures resulted in scaffolds with favorable mechanical and biological properties, including higher tensile strength when compared to collagen/elastin/PCL constructs.
TL;DR: The use of scaffolds composed of a major fraction of multiwall carbon nanotubes and a minor one of chitosan, and with a well-defined microchannel porous structure as biocompatible and biodegradable supports for culture growth is described.
TL;DR: The findings indicate that cells survive the extrusion and that their subsequent viability was not different from that of unprinted cells, indicating that this 3D fiber deposition system is suited for the development of bone grafts containing multiple cell types.
Abstract: Organ or tissue printing, a novel approach in tissue engineering, creates layered, cell-laden hydrogel scaffolds with a defined three-dimensional (3D) structure and organized cell placement. In applying the concept of tissue printing for the development of vascularized bone grafts, the primary focus lies on combining endothelial progenitors and bone marrow stromal cells (BMSCs). Here we characterize the applicability of 3D fiber deposition with a plotting device, Bioplotter, for the fabrication of spatially organized, cell-laden hydrogel constructs. The viability of printed BMSCs was studied in time, in several hydrogels, and extruded from different needle diameters. Our findings indicate that cells survive the extrusion and that their subsequent viability was not different from that of unprinted cells. The applied extrusion conditions did not affect cell survival, and BMSCs could subsequently differentiate along the osteoblast lineage. Furthermore, we were able to combine two distinct cell populations wi...
TL;DR: In this article, the authors discuss approaches for isolation, characterization and directing differentiation of human mesenchymal stem cells (hMSC) and an update of the current clinical use of the cells is also provided.
Abstract: Mesenchymal stem cells (MSC) are a group of clonogenic cells present among the bone marrow stroma and capable of multilineage differentiation into mesoderm-type cells such as osteoblasts, adipocytes and chondrocytes. Due to their ease of isolation and their differentiation potential, MSC are being introduced into clinical medicine in variety of applications and through different ways of administration. Here, we discuss approaches for isolation, characterization and directing differentiation of human mesenchymal stem cells (hMSC). An update of the current clinical use of the cells is also provided.
TL;DR: Although these platforms represent a first attempt to mimic the complex temporal and spatial microenvironment presented in vivo, an increased symbiosis of material engineering, drug delivery technology and cell and molecular biology may ultimately lead to biomaterials that encode the necessary signals to guide and control developmental process in tissue- and organ-specific differentiation and morphogenesis.
TL;DR: It is supposed that highly porous electrospun fibrous scaffolds could be constructed by this elaboration and may be used for skin tissue engineering.